Wednesday, February 28, 2007

Monday, February 26, 2007

Enteral Nutrition


Besides providing systemic nutrition, what are the benefits of enteral nutrition?

Avoids GI mucosal atrophy
Maintains gut-associated lymphoid tissue
Decreases infectious complications from bacterial translocation
Yields better glycemic control than parenteral nutrition
Less risks compared to parenteral nutrition (i.e. central venous catheter-related complications)
Less cost than parenteral nutrition


Do all patients benefit from early enteral nutrition?

No. Prospective randomized controlled trials (RCTs) show that patients with Albumin > 4g/dl undergoing GI surgery have no differences in outcome and complications when receiving enteral nutrition compared to maintenance IV solutions in the initial days following surgery.
However, most prospective RCTs and meta-analyses show that patients with severe abdominal or thoracic trauma have decreased infectious complications with early enteral nutrition compared to unfed or parenteral nutrition. The exception is patients with closed-head injury.


What is special about head trauma patients?

They are at risk for gastroparesis, with a higher risk of aspiration.


What are indicators of gastroparesis?

Gastric residuals >200mL over 4-6hrs
Abdominal distension


Consider NGT decompression and postpyloric feeding.


What about patients with enterocutaneous fistula?

Enteral support is acceptable for low output enterocutaneous fistulas (<500 ml/day)


When is a good time to institute enteral feeds?

Early enteral support should be instituted following resuscitation from major trauma and patients where a prolonged postoperative recovery is anticipated.


Healthy patients with good nutritional status can tolerate 10 days on maintenance fluids before significant protein catabolism occurs.


Among hospitalized patients, how many present with alterations in nutritional parameters?

15-65%, and once hospitalized with an obligated fast, 50-100% become undernourished!


Should I start enteral feeds through a nasogastric tube?

Acceptable for short-term, but has aspiration risks, and often dislodges.


Reserve for intact mental status and protected laryngeal reflexes.


What are problems associated with postpyloric nasojejunal tubes?

They are often difficult to place, and may need assistance with fluoroscopic guidance.


What is a PEG?

Percutaneous endoscopic gastrostomy


What are common indications for PEG placement?

Major facial trauma
Impaired swallowing
Oropharyngeal or esophageal obstruction
Cerebrovascular disease
Chronic neurological disorders


What are contraindications to PEG placement?

Gastric neoplasm
Ascites
Coagulopathy
Varices
Abdominal Wall Defect
Inability to perform endoscopy or transilluminate abdominal wall


What are the two techniques for PEG placement?

1. The Push Technique - uses a Foley catheter pushed through the abdominal wall via Seldinger technique using dilators
2. The Pull Technique - uses a long tapered PEG tube pulled from the mouth through the stomach across the abdominal wall via Seldinger technique

PEG tubes come in sizes ranging from 16-28Fr, but 20Fr is commonly used.


How many surgeons are necessary to perform a PEG?

Two. One to perform endoscopy, and one to place the catheter.


What are the components of the "Pull Technique" for PEG placement?

1. IV sedation for endoscopy, with patient placed supine.
2. Placement of endoscope in stomach with inspection and insufflation.
3. Endoscopic transillumination of upper anterior abdominal wall (usually proximal to incisura)
4. Depress abdominal wall where light is seen... endoscopist should visually confirm indentation.
5. Infiltrate skin at site with local anesthetic.
6. Use a #11 blade to make 5-10mm skin incision.
7. Place 14G needle through incision into insufflated stomach.
8. Allow endoscopist to position snare near the needle.
9. Thread guidewire through needle into the stomach, allowing endoscopist to snare the guidewire. The needle can be removed.
10. Once guidewire is secured, it is pulled out of the mouth along with the scope.
The guidewire now passes through the abdominal wall into the stomach, then proximally out the mouth.
11. The endoscopist will secure the tapered end of the PEG tube to the proximal end of the guidewire.
12. The guidewire should be pulled away from the abdominal wall, which will gradually pull the PEG tube into position in the stomach up against the anterior abdominal wall.
13. A securing external bolster device can be fitted against the skin to keep the tube in position.
14. The endoscopist should visually confirm that the PEG balloon/internal bolster is adequately positioned (snug but not tight).


What are complications of PEG placement?

Wound infection
Bleeding
Peritonitis / Leak
Bowel perforation (Transilluminate!)


What is a PEGJ?

Allows for postpyloric access by passing a 9-12F tube through an existing PEG via endoscopic or fluoroscopic guidance.


Are systemic prophylactic antibiotics recommended for PEG placement?

Yes, there is Level 1 evidence that they decrease peristomal infection rates (Cochrane review)


How long is it recommended that a new PEG remain in situ before it is changed or replaced to a button?

6 weeks


What are surgical options for enteral access?

Gastrostomy
Jejunostomy


Can be performed open or laparoscopic, depending on ability and situation.


What is a Stamm Gastrostomy?

A series of opposing inner and outer purse-string sutures are used to secure a Foley catheter that has been passed through the anterior abdominal wall into the stomach. The sutures are then secured to the anterior abdominal wall, ensuring that the stomach is pexied in place.


What is a Witzel Jejunostomy?

After placement of a purse-string suture around a red rubber catheter that has been introduced into the jejunum, a seromuscular tunnel is sewn around the catheter using interrupted Lembert stitches for about 5cm. The catheter is then fixed to the abdominal wall. This can be performed longitudinally or transversely.


What is a Needle-Catheter Jejunostomy?

Utilizes a 6Fr catheter that is tunneled in the seromuscular space of the intestinal wall before it enters the intestinal lumen.


What are indications for surgical jejunostomy?

Patients undergoing major abdominal surgery where prolonged ileus or recovery is expected, or patients who are malnourished, hypermetabolic, septic, or may be undergoing postoperative chemotherapy or radiotherapy and requiring additional nutritional support.


What is the only absolute contraindication for a jejunostomy or postpyloric feeding?

Distal obstruction


Patients with pancreatitis can receive postpyloric feeds!


What is the caloric density of most isotonic enteral formulas?

1.0 kcal/ml


Why do some formulas contain fiber?

Fiber increases intestinal transit time
Fiber stimulates pancreatic lipase activity
Soluble fiber binds bile acid and cholesterols
Soluble fiber is metabolized by bacteria into short-chain fatty acids


Why should we care about short-chain fatty acids?
It is the primary fuel for the colonocyte!


What do immune-enhancing formulas often contain?

glutamine
arginine
branched-chain amino acids
omega3 fatty acids


They cost more, but have uncertain benefit!


Why do we care about glutamine?
It is the primary fuel for the enterocyte!
Lymphocytes and macrophages also love glutamine...
It is a precursor to glutathione (cellular anti-oxidant)


Why do we care about arginine?

It has a role in up-regulating immune function and promoting wound healing.
It is a substrate for nitric oxide synthase.
It affects anabolic hormone release including growth hormone, glucagon, prolactin, and insulin.


Why do we care about omega-3 fatty acids?

They decrease the inflammatory response (i.e. prostaglandins)

What is the caloric density of fluid-restriction formulas?

1.5-2.0 kcal/ml


What is the content of elemental formulas?

Predigested nutrients


These are higher in osmolality, but considered in situations such as malabsorption, gut impairment, and pancreatitis.


What is bolus feeding?

Delivering 200-500ml of formula over a short amount of time (i.e. 5 minutes).


This is the most physiologic, and typically only into the stomach.


What is intermittent feeding?

Infusing a volume delivered by gravity drip over 20-30 minutes.


What is continuous feeding?

Enteral delivery using an infusion pump, typically over 12-24 hours.
Usually increased by 10-25ml/hr every 4+ hours to a desired goal rate.


Required for postpyloric feeds.


What are potential nasty complications of enteral feeding in the setting of global hypoperfusion?

pneumatosis intestinalis and small bowel necrosis


Delay enteral nutrition until adequate resuscitation has been acheived!


What is "trophic" feeding?

Using enteral nutrition to complement parenteral nutrition, by administering enough as tolerated to stimulate intestinal trophism, while providing primary nutritional support via TPN.
Used in patients who cannot tolerate full enteral nutrition.



Late... SG

Sources:
Schwartz' Principles of Surgery, 8th ed.
O'Leary's Physiologic Basis of Surgery, 3rd ed.
Scott-Connor's The SAGES Manual: Fundamentals of Laparoscopy and GI Endoscopy (1999)
Lipp A, Lusardi G. Systemic antimicrobial prophylaxis for percutaneous endoscopic gastrostomy. Cochrane Database of Systematic Reviews 2006, 4 :CD005571.
Tapia J, Murguia R, Garcia G, de Los Monteros PE, Onate E. Jejunostomy: Techniques, Indications, and Complications. World J Surg 1999; 23: 596-602.

Friday, February 23, 2007

Cold Injury



What is frostnip?

A mild form of cold injury that is reversible, characterized by numbness, pain, and pallor. Frequent on exposed digits, ears, and nose.


What is frostbite?

Irreversible tissue damage caused by ice crystal formation leading to cellular death. Characterized by initial tissue freezing injury, followed by reperfusion injury during rewarming.


How is frostbite severity graded?

First degree: No blistering; tissue is frozen with hyperemia and edema
Second degree: Frozen tissue with hyperemia, edema, and large, clear blisters
Third degree: Death of subcutaneous tissues and skin leading to small, hemorrhagic blisters
Fourth degree: Necrosis, gangrene, and full-thickness tissue loss.


What are chilblain and pernio?

Terms describing local cold injury characterized by pruritic skin lesions on the face, anterior surface of the tibia, or dorsum of the hands and feet.
Associated with a chronic vasculitis of the dermis, provoked by repeated exposure to cold (not freezing) temperatures.
Can be managed with antiadrenergics or calcium channel blockers.


What is trench foot?

Nonfreezing injury to hands or feet caused by chronic exposure to wet conditions just above freezing. Involves alternating vasospasm and vasodilatation leading to eventual ulceration.


What is the management of frostbite?

1. Remove patient from cold environment. Do not rub or exercise the extremity.
2. Manage ABCs, addressing systemic hypothermia and fluid resuscitation.
3. Rapidly rewarm tissue by immersion in a warm water bath of 40-42 degrees C.
4. Provide narcotic analgesia as necessary.
5. Address tetanus status.
6. Cleanse and dry skin of affected area.
7. Keep affected extremity elevated to minimize edema, with cotton between digits to prevent maceration.
8. Consider angiography and thrombolytic therapy
9. Allow demarcation of tissue necrosis.
10. Monitor for compartment syndromes during the rewarming phase


When is amputation and surgical debridement recommended?

Delayed for 2-3 months, unless tissue becomes infected or sepsis intervenes.


Often, permanent tissue loss is less than expected.
"...of all the factors in the treatment of frostbite that may influence outcome, premature surgical intervention by any means, in any amount, was by far the greatest contributor to poor results."


Allow the devitalized tisue to demarcate!


Besides tissue necrosis, what are some skin complications after frostbite?

Hyperhidrosis
Neuropathy
Decreased nail and hair growth
Persistent Raynaud's phenomenon



Late... SG

Source:
Jurkovich GJ. Environmental Cold-Induced Injury. Surg Clin N Am 2007; 87: 247-267.

Thursday, February 22, 2007

Hypothermia and Drowning



Grey's Anatomy (ABC) has recently presented a series of episodes that has examined the management of a situation of mass casualty. However, in a plot twist that has been milked for a couple weeks, our heroine, Dr. Meredith Grey, had been pushed into the Pacific Ocean after skillfully tying off a major vessel in a trauma patient, tourniquet unnecessary. After rescue from drowning by her dashing suitor, Dr. Derek 'McDreamy' Shepherd, she now presents to good old Seattle Grace... hypothermic and unresponsive. What ever shall we do?


Remember, a moist, cold Meredith isn't dead... until she's warm and dead.


Are there any recommendations for how to remove a drowning victim out of the water?

It has been suggested that patients be lifted in the prone position.


Immersion in water results in an increase in cardiac output due to decreased resistance to flow. Removing a person from water in an upright position can cause venous pooling from circulatory collapse that is attributed to deaths seen within minutes of rescue in responsive patients.


What measures should be done at the scene of a drowning victim?

Wet clothing should be removed and the patient wrapped in thick blankets.
Don't waste time rewarming patient.
Transfer patient to facility that has available extracorporeal rewarming.
Intubate the patient if unconscious.
Continuous chest compressions should be applied for cardiopulmonary arrest.
Protect C-spine


What about defibrillation at the scene?

When the myocardium is cold, this will be ineffective...


What factors have favorable outcomes with near drowning?

Submersion less than 5 minutes
Heart beat that is restored immediately
Immersion in ice cold water (less than 5 degrees C)
Buoyancy devices decrease aspiration risk


What factors have possible complications?

Fresh water causes more V/Q mismatch than salt water
River water causes potential risk of infection (leptospirosis)
Shallow water raises possibility of fractures


What is hypothermia?

Core body temperature below 35 degrees C
Mild: 32-35 degrees C (89.6-95.0 F)
Moderate: 28-32 degrees C (82.4-89.6 F)
Severe: <28 degrees C (<82.4 F)


What is primary hypothermia?

Decrease in core temperature from environmental stress


What is secondary hypothermia?

Unintentional hypothermia from abnormal thermoregulation.
Risk factors include age, hypothyroidism, hypoadrenalism, trauma, hypoglycemia, anesthetics.


Below what temperature is shivering abolished?

Somewhere between 30-33 degrees C.


What happens to the cardiac conduction system with moderate to severe hypothermia?

Below 30 degrees C atrial fibrillation, bradycardia, and ventricular dysrhythmias become common.
Below 25 degrees C asystole occurs.


What is the eponym attributed to hypothermia-related gastric erosions?

Wischnevsky's ulcers


What does mild, postoperative hypothermia do to surgical wound infection rates?

-1.9 degrees C core hypothermia triples the incidence of SSIs and increases the hospital stay by 20%


What is the mortality rate for trauma patients with moderate primary hypothermia?

Approximately 20%


Does intentional hypothermia (32-33 degrees C) protect against severe traumatic brain injury?

No. A multicenter randomized clinical trial for GCS 3-7 patients showed no difference in mortality (28% vs. 27%) and greater hospital days and complications when comparing 48hrs of intentional hypothermia with normothermia.


Does intentional hypothermia protect against complications of cardiac arrest?

Yes. A prospective multicenter randomized clinical trial of patients in ventricular fibrillation found cooled patients had better neurologic outcomes (55% vs 39%), lower mortality (41% vs 55%), but higher rates of bleeding, sepsis, and pneumonia.


What is the triad of death?

Acidosis, Hypothermia, and Coagulopathy


How does hypothermia cause coagulopathy?
1. Decrease in clotting factor enzymatic function
2. Qualitative platelet dysfunction


What is passive external rewarming?

Allowing the ambient air to spontaneously warm the patient.


What is active external rewarming?

Placing blankets, heating pads, bair huggers, or applying heat lamps on the patient
Immersing the patient in warm water


What are methods of active core rewarming?

Heated intravenous fluids
Heated bladder, gastric, or colonic lavage
Heated peritoneal or thoracic lavage
Heated humidified inhaled air
Extracorporeal circulatory rewarming


What maximum temperatures are safe for intravenous rewarming?

Blood heated to 42 degrees C
Crystalloids heated to 65 degrees C


What are methods of extracorporeal circulatory rewarming?

1. Cardiopulmonary bypass
2. CAVR - continuous arteriovenous rewarming


What is a limitation of cardiopulmonary bypass?

The need for systemic anticoagulation


What does CAVR involve?

Connecting the patient to a counter-current heat exchange circuit but relying on the intrinsic cardiac pump

How much effort does it take to warm a 70kg patient by 1 degree C?

Using 41 degree C humidified inspired air - more than 6 hours
Using 44 degree C body cavity lavage - 14 L of fluid
Using 40 degree C extracorporeal rewarming - 10 times faster than lavage


What is the pathophysiology of "rewarming shock"?

Peripheral rewarming results in peripheral vasodilatation. In the absence of adequate volume resuscitation this will result in decreased cardiac output.


What is "afterdrop"?

A decrease in core central temperature after cold peripheral blood returns to circulation secondary to vasodilation from rewarming measures.



Late... SG


Sources:
Harries M. Near drowning. BMJ 2003; 327: 1336-1338.
Jurkovich GJ. Environmental Cold-Induced Injury. Surg Clin N Am 2007; 87: 247-267.

Sunday, February 18, 2007

Abdominal Compartment Syndrome

What are factors posing a risk for abdominal compartment syndrome?

Major trauma; damage control
Extensive burns
Large volume fluid resuscitation
Bowel distension from ileus, obstruction, or third spacing
Closure of abdomen under tension
Ischemia-reperfusion injury
Coagulopathy


What is abdominal compartment syndrome?

Intra-abdominal hypertension associated with end-organ dysfunction.


What are the three clinical findings associated with abdominal compartment syndrome?

1. Hypotension
2. Oliguria
3. Elevated peak airway pressures


What is the pathophysiology of abdominal compartment syndrome?

-Intra-abdominal hypertension decreases venous return and stroke volume, while increasing afterload, leading to a decrease in cardiac output.
-Decreased renal blood flow and GFR stimulates the renin-angiotensin-aldosterone system. However, direct renal vascular compression may lead to oliguria not responsive to volume.
-The diaphragm is displaced, decreasing TLC and FRC and increasing inspiratory pressures.
-Mesenteric flow decreases leading to splanchnic venous congestion, bowel mucosal edema, and acidosis.

What is intra-abdominal hypertension?

Intra-abdominal pressures greater than 10 mmHg


In the setting of intra-abdominal hypertension, what happens to CVP and PCWP readings?

Both appear elevated, even though the patient may have intravascular volume depletion.


What is a grading system used for intra-abdominal hypertension?
Grade I 10-15 mmHg - Maintain euvolemia
Grade II 15-25 mmHg - Volume expansion, may need surgery
Grade III 25-35 mmHg - Consider abdominal decompression
Grade IV >35 mmHg - Needs abdominal decompression with re-exploration


Signs of abdominal compartment syndrome usually do not manifest until Grade II intra-abdominal hypertension (greater than 15 mmHg or 20 cmH2O).


How do you measure abdominal pressures?

The most common surrogate is the measurement of bladder pressures.
1. Inject 50mL NS into the aspiration port of a Foley catheter.
2. Place an occlusive clamp distally, or use a 3-way stopcock.
3. Insert a needle into aspiration port and connect to a CVP manometer.
4. Zero the manometer at the pubic symphisis.


Note that different publications report their units in cmH2O (direct measurement of height of column of water) or mmHg (what most CVP manometers will read). The conversion factor is 1 mmHg = 1.36 cmH2O.


What are two independent predictors for the development of abdominal compartment syndrome in non-trauma surgical patients?


1. Elevated peak airway pressures
2. Positive 24-hr fluid balance


When is abdominal decompression generally recommended?

1. IAP greater than 20mmHg with UOP less than 0.5ml/kg/h, peak airway pressure greater than 45 cmH2O, and DO2 less than 600ml/min/m2.
2. IAP greater than 25mmHg.


There are no hard and fast rules here, but avoid signs of organ dysfunction!


What are outcomes of abdominal decompression?

80% of patients have improvement in organ function.
Overall there is a mean survival rate of 53% (reports of 17-75%)!


Are there methods to prevent abdominal compartment syndrome?

Avoid primary fascial closure after damage control laparotomy or if the patient is at high risk at the time of the index operation.
-Temporary towel clip closure
-Prosthetic mesh closure
-Vacuum-assisted closure device


What are some methods of dealing with an open abdomen after decompressive laparotomy?

1. Bogota bag - suture sterile irrigation bag to the skin to protect abdominal viscera
2. Pack abdomen with saline gauze then cover with Ioban, with or without sump drains
3. Prosthetic mesh closures (some have built-in zippers or velcro)
4. Vacuum-assisted closure devices


Protect the fascia if possible so it can be saved for definitive closure!



Late... SG

Sources:
Schwartz' Principles of Surgery, 8th ed.
Moore AFK, Hargest R, Martin M, Delicata RJ. Intra-abdominal hypertension and the abdominal compartment syndrome. Br J Surg 2004; 91: 1102-1110.

Saturday, February 17, 2007

Exploratory Surgery


Watch out for colon darts... SG

Friday, February 16, 2007

Burn Resuscitation


How should you start evaluating a burn patient?

ABCs: Assess airway, breathing, circulation


Be sure to rule out life threatening injuries including open pneumothorax, tension pneumothorax, hemothorax, and cardiac tamponade. The patient may have burns as well as other injuries related to a blast injury, MVC, fall, or other trauma.


What will give you a high index of suspicion for early intubation?

Any sign of inhalation injury:
oropharyngeal swelling, edema
facial burns or soot
singed nasal hairs
hoarseness, stridor, wheezing, rhonchi
mucus, carbonaceous sputum
elevated carboxyhemoglobin level


What is the half-life of carbon monoxide in the blood?

At room air (21% O2) - 4hrs
At 100% O2 - 45-60 minutes


How do you estimate burn severity in total body surface area?


The Rule of Nines
Include only second and third degree burns:
each upper extremity = 9%
each lower extremity = 18%
anterior trunk = 18%
posterior trunk = 18%
head and neck = 9% (20% in infants!)
perineum = 1%


Another good measure is the palmar hand surface = 1%TBSA


What is the Parkland Formula?

A method for burn resuscitation. After assessing the extent of burns, calculate total volume as follows:

4 ml/kg/%TBSA Lactated Ringers over 24h
Give half in the first 8hrs and the remainder in the following 16hrs.


What is the Modified Brooke Formula?

Another method for burn resuscitation
2 ml/kg/%TBSA LR over 24h


What are good endpoints for resuscitation?

Adequate end-organ perfusion...
Urine output > 0.5 ml/kg/hr (adults)
> 1.0 ml/kg/hr (children)
> 1-2 ml/kg/hr (infants)


Why so much fluid?

Local injury leads to histamine release from mast cells, disrupting endothelial tight junctions.
Local and systemic cytokine release leads to SIRS (systemic inflammatory response syndrome) and increased vascular permeability.
Vascular leak leads to third spacing (plasma volume decreases while total extracellular fluid compartment increases).


What is Starling's Law?

Plasma proteins create an inward oncotic force that counteracts an outward hydrostatic pressure.


So, what about colloid resuscitation?

Controversial, but are generally seen to not have an advantage over crystalloid resuscitation, and may be detrimental, at a higher cost. Nice in theory...
Some advocate colloids after 24hrs in burn patients, but not in the initial resuscitation phase because of the large fluid shifts.


What is a potential consequence of overresuscitation?

Abdominal compartment syndrome


What happens with large volume resuscitation with normal saline?

Hyperchloremic metabolic acidosis


Lactated Ringer's is generally recommended to avoid this...



Late...SG

Source:
Schwartz' Principles of Surgery, 8th ed.

Thursday, February 15, 2007

Levels of Evidence

How does the US Preventive Services Task Force grade its recommendations?

Grade A - Strong Recommendation; Good evidence of improved outcomes with benefits that substantially outweigh risks to patients
Grade B - Recommendation; Fair evidence of improved outcomes with benefits that outweigh risks to patients
Grade C - No Recommendation for or against; Fair evidence of improved outcomes with risks and benefits that are similar
Grade D - Recommendation against routine use; Fair evidence of ineffectiveness or risks that outweigh benefits.
Grade I - Insufficient evidence to assess based on power of studies, flaws in study design, or lack of information


What are Levels of Evidence?

A method of ranking the validity of an intervention based on the study design and quality, and the homogeneity of results.


The Oxford Centre for Evidence-based Medicine has a nice table on their webpage...


What is the hierarchy of study design types?

1. Meta-analyses and Systematic Reviews of Randomized Controlled Trials
2. Randomized Controlled Trials
3. Observational Studies (Cohort and Case-Control Studies)
4. Non-experimental Studies (Case Series)
5. Expert Opinion

What is Level 1 Evidence?

1a - Strong evidence from at least one meta-analysis or systematic review of multiple well-designed randomized controlled trials.
1b - Strong evidence from an individual randomized controlled trial with a narrow confidence interval
1c - "All or none" results from a study (i.e. all patients cured from an intervention)


What is Level 2 Evidence?

2a - Strong evidence from at least one meta-analysis or systematic review of multiple well-designed cohort studies.
2b - Strong evidence from an individual cohort study
2c - Outcomes research


What is Level 3 Evidence?

3a - Strong evidence from at least one meta-analysis or systematic review of multiple well-designed case-control studies
3b - Strong evidence from an individual case-control study


What is Level 4 Evidence?

Evidence from non-experimental studies (i.e. case series) and poor quality cohort and case-control studies.


What is Level 5 Evidence?

Opinions of expert committees or respected authorities based on general clinical knowledge, extrapolation of ideas, surrogate outcomes, or principles from bench research.


What is the "gold standard" of study designs?

Double-blinded placebo-controlled randomized clinical trial


However, acheiving the goal of a randomized clinical trial may not be ethical, especially in the context of surgical therapies. In addition, time and costs may be prohibitive.


What is a cohort study?

A study where groups of patients with and without a specified exposure (i.e. Tamoxifen) are followed over a period of time for the onset of a disease (i.e. contralateral breast cancer). This can be defined prospectively or retrospectively.


What is a case-control study?

A study that begins with patients with and without an outcome or disease (i.e. mesothelioma), then examines for possible risk factors (i.e. asbestos exposure, smoking).

What is a cross-sectional study?

A study that summarizes the characteristics of population at a given time, demonstrating both disease and exposure prevalence.


Late... SG

Sources:
US Preventive Services Task Force Guide to Clinical Preventive Services
Oxford Centre for Evidence-Based Medicine

Wednesday, February 14, 2007

Adrenal Incidentaloma

This past week's edition of NEJM includes a review article on Adrenal Incidentaloma... This makes a nice opportunity to talk about this frequently covered topic.


What is an adrenal incidentaloma?

An adrenal tumor discovered during imaging studies performed for other indications


What is the prevalence of adrenal incidentaloma?

6% in autopsy series
4% in patients receiving abdominal CT


What are the three questions you need to ask yourself when evaluating an incidentaloma?

1. Is it functional?
2. Is it a primary adrenal malignancy?
3. Is it a metastasis?


What are the first steps in the management of an adrenal incidentaloma?

1. History and Physical
2. Hormonal Evaluation


What hyperfunctional tumors or syndromes do you want to screen for in the initial evaluation?

1. Cushing's Syndrome, up to 20%
2. Pheochromocytoma, 5%
3. Aldosteronoma, 1%


What is Cushing's Syndrome?

Hypercortisolism


This may be subclinical, but manifested by hypertension, obesity, diabetes mellitus, and osteoporosis.


How can you evaluate for Cushing's Syndrome?

Overnight dexamethasone (1mg) suppression test


If this is positive (greater than 5ug/dL), the test may be confirmed with serum corticotropin, serum cortisol, 24-hr urine cortisol, and a high-dose dexamethasone suppression test.


When performing an adrenalectomy for a cortisol-secreting tumor, what considerations do you have to make?

The other adrenal will be suppressed, so perioperative glucocorticoids should be given.


How do you screen for pheochromocytoma?

Check a 24-hr urine sample for fractionated metanephrines and catecholamines.


What are confirmatory imaging studies for pheochromocytoma?

MIBG Scintigraphy
MRI showing high signal intensity when T2 weighted
CT showing heterogeneous and vascular tumor with increased attenuation


What is a MIBG Scan?

A nuclear study using I-131 MetaIodoBenzylGuanidine, a substrate that is concentrated in catecholamine storage vesicles. Thus study may be helpful for evaluating patients for pheochromocytomas and neuroblastomas.

How do you screen for aldosteronoma?

The patient is typically hypertensive with hypokalemia
Assess plasma aldosterone:renin ratio (morning levels, off spironolactone, eplerenone, or amiloride)


What is a saline infusion test?

This is a confirmatory test for primary aldosteronism, where saline loading (2L bolus) fails to suppress plasma aldosterone levels below 8.5 mg/dL after having the patient lie supine for 4hrs.


Once you are assured that the incidentaloma is not hormonally active, what are you still suspicious of?

1. Adrenocortical carcinoma
2. Metastasis


What are suspicious findings on CT?

Heterogeneous, vascular lesion with irregular margins, necrosis, hemorrhage, or calcifications, high signal attenuation with slow washout of contrast material


Adrenal adenomas have high lipid content, leading to low attenuation. They also have rapid washout of contrast material (more than 50% in 10 minutes)


What are suspicious findings on MRI?

Hyperintensity relative to the liver on a T2-weighted image


Why does size matter?

Lesions greater than 4cm have a 90% sensitivity and 24% specificity for adrenocortical carcinoma. Adrenalectomy is recommended for these lesions.


What tumors metastasize to the adrenals?

Lung, kidney, colon, breast, esophagus, pancreas, liver, and stomach.
Often bilateral


What are considerations to be made before choosing to FNA an adrenal tumor?

Pheochromocytoma must first be ruled out to avoid a hypertensive crisis. In general, should be reserved for patients who are not candidates for surgical resection, but where the results of biopsy may impact therapy.


What are the most likely diagnoses with bilateral incidentalomas?

1. Metastatic disease
2. Congenital adrenal hyperplasia
3. Bilateral cortical adenomas


What are recommendations for the follow-up of a patient with a nonfunctioning incidentaloma?

Repeat imaging studies at 6, 12, and 24 months
Repeat hormonal evaluation yearly for 4 years
Adrenalectomy for lesions greater than 4cm, or if enlarges more than 1cm during observation, or if patient develops evidence of autonomous hormonal secretion



Late... SG

Sources:
Norton's Surgery: Basic Science and Clinical Evidence
Mastery of Surgery, 5th ed.
Young WF. The Incidentally Discovered Adrenal Mass. NEJM 2007; 356(6): 601-610.

Tuesday, February 13, 2007

Clocks

This is amazing...


Late... SG

Monday, February 12, 2007

Cancer Statistics, 2007

Every year, the American Cancer Society publishes a paper reviewing updates to US cancer incidence and mortality rates, as well as estimated projections, using data obtained from cancer registries and SEER (Surveillance, Epidemiology, and End Results... a program of the NCI).

The link to the free open access paper is a click away:
Jemal et al. Cancer Statistics, 2007. CA Cancer J Clin. 2007; 57: 43-66.

What cases do the cancer estimates not include?

Carcinoma in situ, except urinary bladder
Basal cell carcinomas
Squamous cell carcinomas of the skin


What are the top three leading sites of new cancer in males?

1. Prostate, 29%
2. Lung and Bronchus, 15%
3. Colorectal, 10%


What are the top three causes of cancer death in males?

1. Lung and Bronchus, 31%
2. Prostate, 9%
3. Colorectal, 9%


What are the top three leading sites for new cancers in females?

1. Breast, 26%
2. Lung and Bronchus, 15%
3. Colorectal, 11%


What are the top three causes of cancer death in females?

1. Lung and Bronchus, 26%
2. Breast, 15%
3. Colorectal, 10%


What US states have the lowest and highest incidence of lung cancer?

Utah has the lowest (also ranks lowest in adult smoking prevalence)
Kentucky has the highest (also ranks highest in adult smoking prevalence)


What are the trends in lung cancer incidence rates?

After steadily increasing for decades, lung cancer incidence rates are declining in men and plateauing in women.


What has happened to the total number of cancer deaths?

For the second consecutive year, the total number has decreased.


What are the top ten leading causes of death in the US?

1. Heart disease, 27%
2. Cancer, 23%
3. Cerebrovascular disease, 6%
4. Chronic lower respiratory diseases, 5%
5. Accidents, 5%
6. Diabetes mellitus, 3%
7. Alzheimer disease, 3%
8. Influenza and pneumonia, 3%
9. Nephritis, nephrotic syndrome, and nephrosis, 2%
10. Septicemia, 1%


What is the leading cause of death among women between 40-79y and men between 60-79y?

Cancer


Among males less than 40y, what is the most common fatal cancer?

Leukemia


What about males greater than 40y?

1. Lung Cancer
2. Colorectal if 40-79y, Prostate if older than 80y


What is the leading cause of cancer death in females less than 20y?

Leukemia


What is the leading cause of cancer death in females between 20-59y?

Breast cancer


What is the leading cause of cancer death in females older than 60y?

Lung cancer


In the US, what are the three most common causes of death in children (1-14y)?

1. Accidents, 37%
2. Cancer, 12%
3. Congenital Anomalies, 8%


What are the most common childhood (1-14y) cancers?

1. Leukemia (especially ALL)
2. Brain and Nervous System
3. Soft Tissue Sarcomas
4. Non-Hodgkin Lymphoma
5. Wilms Tumors


What has happened to 5-year cancer survival rates among children?

They have improved from 58% (1975-77) to 79% (1996-2002).


Are there racial/ethnic differences in cancer incidence and mortality?

Yes.
African American men have a 15% higher incidence and 38% higher death rate than Caucasian men.
African American women have a 9% lower incidence but 18% higher death rate than Caucasian women.
Stomach and liver cancer incidence and death rates in Asians are twice that of Caucasians (think H. pylori and Hepatitis B)...


What is the estimated lifetime probablity of developing cancer?

45% for men
38% for women (who are more likely to develop cancer before 60y)



Late... SG

Source:
Jemal A, Siegel R, Ward E, Murray T, Xu J, Thun MJ. Cancer Statistics, 2007. CA Cancer J Clin 2007; 57: 43-66.

Sunday, February 11, 2007

Krazy Glue


Krazy Glue you might ask? We'll get there with a case...

A female in her late 70s presents to you with chest pain and is found to have critical aortic stenosis (valve area 0.8 sq-cm). In addition, she has sustained an acute lateral wall MI, but has an ejection fraction of 60% on echo. Angiography confirms AS and demonstrates complete occlusion of the left circumflex artery with no identifiable targets. She is admitted to the CICU and scheduled for aortic valve replacement after the weekend.


How does symptomatic aortic stenosis typically present?

1. Angina pectoris (66%, only half having coronary artery disease)
2. Syncope (25%)
3. Heart Failure


When does aortic stenosis become symptomatic?

Typically, when the aortic valve area is less than 1 sq-cm.


What is the pathophysiology of angina pectoris associated with aortic stenosis?

1. left ventricular hypertrophy places demand on coronary blood supply
2. increased systolic ejection pressures and LVEDP increase myocardial work and oxygen demand
3. prolongation of the systolic ejection time decreases time for diastolic coronary blood flow


Well, in the wee hours of Saturday morning, you are notified that she has acutely decompensated and take her for emergent valve repair. You perform a median sternotomy and are surprised to find upon opening the pericardial sac the presence of a bloody effusion that had been likely causing tamponade. Her hypotension begins to resolve and you place her on cardiopulmonary bypass. You then proceed to manipulate and remove the large amounts of clot, but while filling the heart you cannot locate an obvious site of left ventricular wall rupture... however, the lateral wall has a bruised region from infarct that seems a likely culprit.


What is Beck's Triad?

Classic signs of cardiac tamponade:
1. Elevated venous pressures
2. Systemic arterial hypotension
3. Muffled heart sounds

What are mechanical complications of myocardial infarction?

1. Free rupture of the left ventricular wall
2. Left ventricular aneurysm
3. Ventricular septal defect


Who first described free rupture of the left ventricular wall?

William Harvey in 1647

Harvey also described the nature of blood circulation, hypothesizing that it travelled in a circuit, pumped by the heart (contradicting Galenic theories that blood was constantly absorbed by the body and produced by the liver).


What are methods to repair free rupture of the left ventricular wall?

1. Infarctectomy and buttressed repair with felt strips
2. Placement of a patch with glue


So, you ask for the Krazy glue, hiding a smile behind your mask as you imagine the flailing construction worker suspended by the wiles of his hat. Sure enough, tubes of sterilized store-bought cyanoacrylate appear before you floating in a basin (even with the cute little green push pins). You cut a circular patch of bovine pericardium and adeptly apply the adhesive... then slap it down on the lateral wall. You change gloves and the case then proceeds uneventfully with replacement of the aortic valve.


When were cyanoacrylates given US FDA approval?

In 1998, the FDA gave Closure Medical Corporation (Raleigh, NC) approval to market 2-octyl cyanoacrylate for closing wounds and surgical incisions. In 2002, they were also approved for marketing it as an adhesive that acts as a barrier against microbial penetration. In 2000, n-butyl cyanoacrylate was approved for use as an liquid embolic agent for cerebral AVMs.

What are trade names of marketed medical cyanoacrylates?

Dermabond (Ethicon/J&J) - surgical wound closure
Orabase Soothe-n-Seal (Colgate/Palmolive) - Canker sores
Liquid Bandage (Band Aid/J&J) - Cracked skin, shaving nicks
Nexaband (Abbott) - veterinary wound closure
Trufill (Cordis/J&J) - embolic system for cerebral AVMs
Histoacryl (Braun, Germany), a n-butylcyanoacrylate, has been used worldwide (but not in the US) for some time as a tissue adhesive.


What is the difference between n-butyl and 2-octyl cyanoacrylates?

n-butyl has lower tensile strength and is more brittle


How is Dermabond packaged?

In sterile 0.5ml plastic-encased glass-ampule applicators, or 0.5ml and 0.75ml pen applicators.

How do you apply Dermabond?

1. Make sure the wound is clean with adequate hemostasis.
2. Relieve tension in the wound as necessary with deep dermal suture placement.
3. Crush applicator's glass vial and allow applicator to express adhesive.
4. Approximate wound edges manually or with forceps.
5. Brush thin layer of adhesive on wound without allowing it to enter wound.
6. Allow to polymerize for 30-45 seconds.
7. Add 2 more layers of adhesive, waiting 5-10 seconds between applications.


How do cyanoacrylates work?

Through a polymerization reaction that is catalyzed by the presence of water. The presence of moisture on a surface or in the air will accelerate the process.


What is the role of cyanoacrylates in heart surgery?

Experience using Methyl-2-cyanoacrylate in clinical cardiac surgery was described by Nina S. Braunwald in 1966, who reported its use favorably as a hemostatic agent on the heart and aorta in 24 patients. At the time methyl-2-cyanoacrylate was called Eastman 910 monomer; presently it is marketed as Krazy Glue or Superglue.

Since then, there have been sporadic case reports of sutureless repair of cardiac rupture using glue and patch technique with cyanoacrylates. More recently, Lachapelle et al. reported the results of 6 patients with left ventricular free wall rupture who were managed using an elliptical Teflon felt patch and Histoacryl adhesive, all who acheived hemostasis, with one postoperative mortality related to a stroke.


Who was Nina S. Braunwald?

Nina Starr Braunwald, MD (1928-1992) was the first female to perform open heart surgery. In 1960, she led the operative team that implanted the first artificial mitral valve (the first successful human heart valve replacement), which she created herself out of polyurethane and Teflon. Later, she developed the Braunwald-Cutter valve, a cloth-covered mechanical prosthesis, as well as a stented aortic homograft for mitral valve replacement. She also managed to have a family with three children.



Late... SG

Sources:
Norton's Surgery: Basic Science and Clinical Evidence (2001).
Braunwald E. Nina Starr Braunwald: Some Reflections on the First Woman Heart Surgeon. Ann Thorac Surg 2001; 71: S6-7.
Braunwald NS. A Clinical Evaluation of Methyl-2-cyanoacrylate Monomer as a Hemostatic Agent on the Aorta. Ann Surg 1966; 164(6): 967-972.
Lachapelle K, deVarennes B, Ergina PL, Cecere R. Sutureless Patch Technique for Postinfarction Left Ventricular Rupture. Ann Thorac Surg 2002; 74: 96-101.
Singer AJ, Thode HC. A review of the literature on octylcyanoacrylate tissue adhesive. Am J Surg 2004; 187: 238-248.
www.closuremed.com

Saturday, February 10, 2007

Axillary Lymph Nodes


What are the six groups of axillary lymph nodes?

1. Lateral / Axillary vein group
2. Anterior / Pectoral / External mammary group
3. Posterior / Subscapular group
4. Central group
5. Apical / Subclavicular group
6. Interpectoral group

The lateral / axillary group course along the axillary vein towards the bicipital groove of the humerus.
The posterior / subscapular group follows the subscapular vein and is along the posterior axillary fold and the lateral border of the scapula.
The anterior / external mammary group follows the lateral thoracic vein and is beneath the anterior axillary fold.

The central group receives drainage from froups 1-3 and 6, then drains into the apical group. The apical group can later drain into the suprascapular nodes or into the subclavian trunk.

What are Rotter's nodes?
Nodes of the interpectoral group (between the pectoralis major and minor). These drain into both the apical and central groups.

What demarcates the three levels of axillary lymph node dissection?
Level 1 - lateral to the pectoralis minor
Level 2 - deep to the pectoralis minor
Level 3 - medial to the pectoralis minor

What lymph node groups comprise Level 1 nodes
Anterior / External mammary group
Lateral / Axillary vein group
Posterior / Subscapular group

What lymph node groups comprise Level 2 nodes?
Central node group
Possibly some apical nodes

What lymph node groups comprise Level 3 nodes?
Apical / Subclavicular node group

What surgeon is credited for recognizing that breast cancer can metastasize to internal mammary lymph nodes?
W. Sampson Handley, MS, FRCS

Where do internal mammary lymphatic trunks terminate?
Some drainage to Apical / Subclavicular nodal groups
The right side enters the right lymphatic duct
The left side enters the thoracic duct

What proportion of lymphatic flow from the breast enters axillary node groups?
>75%

What are routes of lymphatic drainage of the breast?
1. Laterally, primarily to the external mammary group (anterior)
2. Medially, to the internal mammary chain
3. Transpectorally, to interpectoral (Rotter's) nodes
4. Retropectorally, directly to apical/subclavicular nodes


Late... SG

Sources:
Mastery of Surgery, 5th ed.
Lachman's Case Studies in Anatomy, 4th ed.
O'Leary's Physiologic Basis of Surgery, 3rd ed.

Friday, February 9, 2007

Axillary Anatomy


What are the borders of the axilla?

apex - cervicoaxillary canal
anteriorly - pectoralis major and minor
posteriorly - subscapularis / teres major / latissimus dorsi
laterally - bicipital groove of humerus
medially - serratus anterior
base - axillary fascia


What are the borders of the cervicoaxillary canal?

anteriorly - clavicle
posteriorly - scapula
medially - 1st rib
This aperture extends into the posterior triangle of the neck


What is the pectoral fascia?

A superficial layer investing the pectoralis major


What is the clavipectoral fascia?

A deep layer extending from the clavicle to the axillary fascia, investing the subclavius and pectoralis minor muscles


What is the costocorocoid membrane?

The superior portion of the clavipectoral fascia, above the pectoralis minor


What pierces the costocorocoid membrane?

1. cephalic vein
2. lateral pectoral nerve
3. thoracoacromial artery


What is the coracoaxillary membrane?

The inferior portion of the clavipectoral fascia, below the pectoralis minor
AKA suspensory ligament of axilla


What is the Halsted Ligament?

Dense condensation of clavipectoral fascia between the medial portion of the clavicle and the 1st rib
Invests the subclavian artery and vein as they traverse the 1st rib


What comprises the anterior axillary fold?

The lateral border of the pectoralis major


What comprises the posterior axillary fold?

Teres major and latissimus dorsi


What does the lateral pectoral nerve supply?

Pectoralis major
This is derived from the lateral cord (C5-7) of the brachial plexus and pierces the costocorocoid membrane.


What does the medial pectoral nerve supply?

Pectoralis major and minor
This is derived from the medial cord (C8, T1) of the brachial plexus and runs on the deep surface of the pectoralis minor, then pierces it to innervate both muscles.


What are the contents of the axillary sheath?

Axillary artery, 1st portion
Axillary vein
Brachial plexus


What are the borders of the 1st portion of the axillary artery?

medially - 1st rib
lateral/inferiorly - pectoralis minor


What are its branches?

Only one: the superior thoracic artery
Supplies the upper serratus anterior and intercostal spaces


What borders the 2nd portion of the axillary artery?

anteriorly - pectoralis minor
medially - medial cord of brachial plexus, axillary vein
laterally - lateral cord of brachial plexus
posteriorly - posterior cord of brachial plexus


What are its branches?

1. Thoracoacromial artery
2. Lateral thoracic artery

Both supply the pectorals. The thoracoacromial artery pierces the clavipectoral fascia and divides into acromial, deltoid, pectoral, and clavicular branches. The lateral thoracic also supplies axillary lymph nodes and the lateral breast.


What are the borders of the 3rd portion of the axillary artery?

medial/superiorly - pectoralis minor
lateral/inferiorly - teres major


What are its branches?

1. Subscapular artery
2. Anterior circumflex humeral artery
3. Posterior circumflex humeral artery
The subscapular artery divides into the circumflex scapular artery (supplies dorsum of scapula) and the thoracodorsal artery (supplies latissimus dorsi).

The anterior CHA passes deep to the biceps brachii and coracobrachialis while winding around the neck of the humerus. The posterior CHA passes through the quadralangular space of the posterior wall of the axilla along with the axillary nerve to supply the deltoid and triceps brachii. Both anastomose...


What would happen with ligation of the axillary artery proximal to the subscapular artery?

Likely nothing due to extensive scapular collateralization between the thyrocervical trunk (3rd branch of subclavian) and the subscapular artery


What would happen with ligation of the axillary artery distal to the subscapular artery?

Distal ischemia


What vessel becomes the axillary vein as it crosses the teres major?

basilic vein


What lies in the deltopectoral groove?

cephalic vein


Where does the cephalic vein drain into the axillary vein?

superior to the pectoralis minor


What does the long thoracic nerve supply?

serratus anterior

The long thoracic n is derived from roots C5-7, enters into the axilla via the cervicoaxillary canal, and lies superficial to the serratus anterior, invested in its fascia. Injury will result in "winged scapula", leading to an inability to abduct the arm above horizontal.


What does the thoracodorsal nerve supply?

latissimus dorsi

The thoracodorsal n is derived from the posterior cord of the brachial plexus and lies medial to the latissimus dorsi. Preservation is imperative for functional latissimus myocutaneous flap reconstructions.


What does the intercostobrachial nerve supply?

sensation to the skin of the apex and lateral axilla and the upper medial and inner aspect of the arm



We'll talk about axillary lymph nodes later... SG

Sources:
Moore's Clinically Oriented Anatomy, 3rd ed.
Mastery of Surgery, 5th ed.

Thursday, February 8, 2007

Aesthetic Surgery

Word on the street...


Rhinoplasty anyone?


Late... SG

Wednesday, February 7, 2007

Pancreatic Transection


What are methods that can be used to help identify pancreatic ductal injury?

1. Operative pancreatography
2. Cannulation with a 1.5-2.0 mm coronary artery dilator
3. ERCP


What surgical options are appropriate for main duct transection at the neck, body, or tail of the pancreas?

1. Distal pancreatectomy with splenectomy
2. Distal pancreatectomy with splenic preservation
3. Distal Roux-en-Y pancreaticojejunostomy


What surgical option is most appropriate for transection at the head of the pancreas?

Roux-en-Y pancreaticojejunostomy


Pancreatic insufficiency will occur with loss of 85-90% of the gland.


What surgical option is appropriate for injury to the intrapancreatic common bile duct?

Roux-en-Y choledochojejunostomy


What surgical options are considered for pancreatoduodenal injuries?

1. Pyloric exclusion
2. Pancreatoduodenectomy


What are indications for a trauma Whipple?

1. Transection of intrapancreatic common bile duct and main pancreatic duct
2. Avulsion of the Ampulla of Vater
3. Destruction of the second portion of the duodenum


What is a common grading system for pancreatic traumatic injury?

Pancreatic organ injury scale from Moore et al. (1990) J Trauma.


Late! SG


Sources:
Schwartz' Principles of Surgery, 8th ed.
Moore EE et al. J Trauma. 1990; 30: 1427-1429.

Tuesday, February 6, 2007

Pulmonary Sequestration


Pulmonary Sequestrations are anomalies in lung bud development with parenchyma that remains isolated from the tracheobronchial tree and has an anomalous systemic blood supply.




Where is the arterial blood supply derived from?

The Aorta



What is the venous drainage of intralobar sequestrations?

Pulmonary Vein


What is the venous drainage of extralobar sequestrations?

Azygous System



Late... SG



Sources:
O'Leary's Physiologic Basic of Surgery, 3rd ed.
Franco J, Aliaga R, Domingo ML, Plaza P. Diagnosis of pulmonary sequestration by spiral CT angiography. Thorax 1998; 53: 1089-1092.

Monday, February 5, 2007

Liver Transplantation


Who performed the first human liver transplant?

Thomas E. Starzl, MD, PhD

1963 - his first human attempt
1967 - his first human success
1999 - most cited man in clinical medicine
2004 - awarded National Medal of Science


What is the most common cause of chronic liver disease in a non-alcoholic?

Viral Hepatitis (C>B)


What are the two most common cholestatic diseases requiring transplantation in adults?

#1 - Primary Biliary Cirrhosis
#2 - Primary Sclerosing Cholangitis (70% having IBD)


What is the most common cholestatic disease requiring transplantation in children?

Biliary atresia


What are optimal tumor size criteria for liver transplantation with hepatocellular carcinoma?

Single lesion smaller than 5cm
Less than 3 lesions smaller than 3cm


What is Wilson's Disease?

An autosomal recessive disorder of copper excretion leading to chronic hepatitis and cirrhosis


What is Budd-Chiari Syndrome?

Hepatic vein thrombosis


What are the most common causes of acute / fulminant hepatic failure?

Acetaminophen overdose
Acute Hepatitis B
Drugs
Hepatotoxins
Wilson's Disease


What are indications for Liver Transplantation?

1. Decompensated cirrhosis


Hepatic encephalopathy
Ascites
Spontaneous Bacterial Peritonitis
Portal hypertensive bleeding
Hepatorenal Syndrome
Malnutrition
2. Fulminant Hepatic Failure


What are contraindications to Liver Transplantation?

Disseminated malignancy: HCC c metastatic disease, vascular invasion, or significant tumor burden
Extrahepatic malignancy (defer 2 years p curative treatment)
Infection / Sepsis
Cardiac and pulmonary issues (i.e., pulmonary hypertension)
Ongoing substance abuse


Pretransplantation evaluation must assess for evidence of:

1. Hepatopulmonary syndrome - intrapulmonary AV shunting
2. Pulmonary HTN - associated c high risk of mortality
3. Hepatorenal Syndrome - requires optimization of renal function pretransplant


The Surgical Procedure can be summarized as follows:


I. Pre-anhepatic Phase : Mobilization of the diseased liver

1. Isolation of supra and infrahepatic vena cava
2. Isolation of portal vein
3. Isolation of hepatic artery
4. Division of the bile duct
5. Application of vascular clamps
6. Recipient hepatectomy


II. Anhepatic Phase : Decreased venous return
Some surgeons elect to use venovenous bypass routinely or selectively (CFA and portal vein are cannulated with venous return via thoracic central line)

1. Orthotopic placement of donor liver
2. Suprahepatic caval anastomosis
3. Infrahepatic caval anastomosis
4. Portal vein anastomosis
5. Removal of portal and caval clamps


III. Post-anhepatic Phase : Characterized by marked changes in hemodynamic parameters

1. Hepatic arterial anastomosis
2. Biliary anastomosis - choledochoduodenostomy or choledochojejunostomy

What is the "Piggyback Technique"?

The recipient's IVC is preserved, with an anastomosis between the suprahepatic donor cava to the confluence of the recipient hepatic veins. The benefit is the recipient cava does not have to be completely cross-clamped during the anastomosis.


What are Donor considerations with a Partial Liver Transplant?

Harvest is from either a living-donor or a split-liver deceased donor
Left lateral segment is ideal for pediatric recipients
Right lobe is ideal for adult recipients


Living donors must be screened for medical fitness, anatomy, and psychosocial issues (r/o coercion)


What are the risks to the living donor?

10-15% morbidity
Less than 0.5% mortality


What are common graft survival rates?

85-90% at one year


deceased donor - 64% at five years with 72% patient survival
living donor - 73% at five years with 86% patient survival


What is the incidence of primary nonfunction of hepatic allografts?

3-5%, with a mortality>80% without retransplantation


What is the most common vascular complication after liver transplant?

Hepatic Artery Thrombosis

This can also result in biliary stricture. Rates are 3-5% in adults and 5-10% in children... higher with partial liver transplants.


How frequently does Hepatitis C recur after transplantation?

Recurrence is almost universal. Tx: Ribavirin and IFN-alpha

Hepatitis B recurrence has decreased with use of HepB IgG and lamivudine (= 3TC = Epivir).
Primary sclerosing cholangitis, HCC, and autoimmune hepatitis are also known to recur


What is the Kasai Procedure?

Portoenterostomy for biliary atresia

This is successful in 40-60% of kids, but 75% of children will still require transplantation secondary to cholestasis and cirrhosis



Phew... That's all for now... SG

Source: Schwartz' Principles of Surgery, 8th ed.

Sunday, February 4, 2007

Femoral Triangle

This one's a quickie:

Click here for a nice illustration.

What are the borders of the femoral triangle?

laterally - Sartorius
medially - Adductor Longus
superiorly - Inguinal Ligament
floor - Adductor Longus / Pectineus / Iliopsoas
roof - Fascia Lata


What are the boundaries of the femoral ring?

laterally - femoral vein
posteriorly - superior ramus of pubis / pectineus
medially - lacunar ligament / conjoint tendon
anteriorly - inguinal ligament


What are the contents of the femoral sheath?

Remember NAVEL (from lateral to medial)?

Well, the femoral nerve actually lies outside the sheath. It gives off the saphenous nerve which later accompanies the femoral artery in the adductor canal.

laterally - femoral artery
intermediate - femoral vein
medially - femoral canal (i.e. femoral hernia)

The profunda femoris a. arises laterally from the CFA 4cm inferior to the inguinal ligament then descends posteriorly. Around the same level, the great saphenous vein pierces the medial wall of the femoral sheath and drains into the femoral vein.

Late! SG

Source: Moore KL. Clinically Oriented Anatomy, 3rd ed.