Faculty Bibliography

BACKGROUND:Intraabdominal pressure (IAP) has been considered responsible for adverse effects in trauma and other abdominal catastrophes as well as in formation and recurrence of hernias. To date, little information is available concerning IAP in normal persons. Our purpose in this study was to measure the normal range of IAP in healthy, nonobese adults and correlate these measurements with sex and body mass index (BMI). METHODS:After Institutional Review Board approval, 20 healthy young adults (< or =30 years old) with no prior history of abdominal surgery were enrolled. Pressure readings were obtained through a transurethral bladder (Foley) catheter. Each subject performed 13 different tasks including standing, sitting, bending at the waist, bending at the knees, performing abdominal crunches, jumping, climbing stairs, bench-pressing 25 pounds, arm curling 10 pounds, and performing a Valsalva and coughing while sitting and also while standing. Data were analyzed by Student's t-test and Pearson's correlation coefficients. RESULTS:Intraabdominal pressure was measured in 10 male and 10 female subjects. The mean age of the study group was 22.7 years (range, 18-30 years), and BMI averaged 24.6 kg/m(2) (range, 18.4-31.9 kg/m(2)). Mean IAP for sitting and standing were 16.7 and 20 mm Hg. Coughing and jumping generated the highest IAP (107.6 and 171 mm Hg, respectively). Lifting 10-pound weights and bending at the knees did not generate excessive levels of pressure with the maximum average of 25.5 mm Hg. The mean pressures were not different when comparing males and females during each maneuver. There was a significant correlation between higher BMI and increased IAP in 5 of 13 exercises. CONCLUSION/CONCLUSIONS:Normal IAP correlates with BMI but does not vary based on sex. The highest intraabdominal pressures in healthy patients are generated during coughing and jumping. Based on our observations, patients with higher BMI and chronic cough appear to generate significant elevation in IAP. Thus, this group of patients may potentially be at increased risk for abdominal wall hernia formation following surgery.

BACKGROUND:Nodular adrenal hyperplasia (NAH) may mimic the biochemical characteristics of an aldosterone-producing adenoma. The authors evaluated the outcomes of unilateral laparoscopic adrenalectomy in the setting of lateralizing aldosterone hypersecretion by NAH. METHODS:Retrospective review of consecutive patients who underwent a laparoscopic adrenalectomy for primary hyperaldosteronism owing to NAH was performed. Patient demographics, perioperative symptoms, medications, radiographic findings, and serum chemistries were analyzed. Response to operation was classified according to postoperative control of hypertension and hypokalemia as resolved, improved, or refractory. RESULTS:From January 1999 to October 2004, 15 patients underwent a laparoscopic unilateral adrenalectomy for hyperaldosteronism owing to lateralizing NAH. Nine (60%) patients presented with > or =5 years of hypertension, including 8 (53%) patients with labile or malignant hypertension. Ten (67%) patients had hypokalemia. Abdominal imaging results were normal in 9 (60%) patients. All patients underwent adrenal venous sampling (94% successfully), which revealed an average adjusted aldosterone ratio of 17.6 (range, 1.2 to 75.9). At a mean follow-up of 26 (range, 4 to 58) months, hypertension had resolved in 4 (27%), improved in 8 (53%), and was refractory in 3 (20%) patients. Hypokalemia resolved in all patients. There were no complications, conversions, or mortalities. CONCLUSION/CONCLUSIONS:This series shows that unilateral adrenalectomy for lateralizing NAH results in eradication of hypokalemia and resolution or significant improvement in hypertension in 80% of patients at long-term follow-up. When lateralization of aldosterone production is noted, laparoscopic adrenalectomy provides significant clinical improvement even in patients with a pathologic diagnosis of NAH.

Since the first procedure by Clayman and colleagues in 1990, laparoscopic nephrectomy has been performed at multiple institutions worldwide and is an accepted approach for benign and malignant renal pathology. We retrospectively compared the outcomes of laparoscopic nephrectomy for renal pathology in patients older than and less than 65 years of age. Data were collected for all patients undergoing elective nephrectomy (simple, radical, and nephroureterectomy) for renal pathology between November 2000 and June 2003. A total of 94 laparoscopic nephrectomies (62 hand-assisted, 32 totally laparoscopic) for renal disease were performed. Indications for surgery included renal cell carcinoma (63), transitional cell carcinoma (7), hypertension (9), chronic pyelonephritis (6), nonfunctioning kidney (4), complex cyst (3), and polycystic kidney disease (2). There were 33 elderly patients (> or = 65 years) and 61 adult patients (< 65 years). The elderly group had a mean operative time (238 min vs 234.3 min; P = 0.89) and blood loss (88.5 mL vs 149.8 mL; P = 0.68) similar to the adult group. Likewise, the incidence of perioperative complications was no different between the two groups (intra-op: 3.0% vs 0%; P = 0.35/post-op: 21.2% vs 16.4%; P = 0.56). The length of hospitalization was longer in the elderly population (5.7 days versus 5.0 days; P = 0.01) compared to the younger adult group. Laparoscopic nephrectomy is well tolerated in the elderly population. For all surgical indications, the use of a minimally invasive approach confers operative times, blood loss, and morbidity that are comparable to those of younger patients. Yet, length of stay remains longer for elderly patients undergoing nephrectomy.

Fiberoptic colonoscopy provides superior diagnostic and therapeutic capabilities in the treatment of lower gastrointestinal disease processes. A well-recognized, but uncommon, complication during the procedure is perforation. The purpose of this study was to determine the incidence of colonoscopic perforation, define risk factors, assess the management of these complications, and evaluate outcomes. From January 1997 through December 2003, 43,609 colonoscopies were performed in our medical center. There were 14 (0.032%) perforations (1 in 3115 procedures); 7 from diagnostic and 7 from therapeutic procedures. General surgeons performed 1243 procedures (2.9%), and their rate of perforation was 0.080 per cent compared with 0.031 per cent for gastroenterologists during the same period. Half of the perforations occurred in the rectosigmoid, and the most common mechanism was mechanical (n = 6). Perforation was identified immediately during endoscopy in 50 per cent of the patients. Thirteen of 14 perforations were treated within 24 hours; 1 was delayed 48 hours. Initial surgical management was undertaken in 11/14 patients. Initial nonoperative treatment was attempted in three and was successful in only one patient. The mean length of stay following perforation was 11.2 days (range, 4-36 days). Three patients (21.4%) had 7 postoperative complications. Colonoscopic perforations are uncommon but can be recognized early and managed surgically with acceptable morbidity and postoperative length of stay.

Incisional herniorrhaphy remains a formidable challenge to the general surgeon. Recurrence rates after primary repair are reported between 31-54 per cent while tension-free repairs with prosthetic mesh have lowered this rate to 10 per cent. Repairs with composite mesh (polypropylene/ePTFE) have been gaining in popularity due to the ease of mesh placement in the intraperitoneal location. This paper reviews our experience with composite repairs at a teaching community hospital. A retrospective chart review was performed which evaluated all patients undergoing abdominal incisional hernia repairs over a 4(1/2)-year period. The data were analyzed for mortality, recurrence, infection, subsequent bowel obstruction, and fistula formation. Two hundred twenty-one incisional herniorrhaphies were identified in the resident database of which 95 were repaired with Composix mesh (Bard Surgical, Cranston, RI) in the intraperitoneal position. There were two (2%) recurrences and eight (8%) infections. Fistulization to the small bowel from exposed polypropylene occurred in one patient. There were no bowel obstructions. One postoperative death occurred secondary to pulmonary embolus. Mesh removal was required in all infected cases, and there was a high incidence (63%) of methicillin-resistant Staphylococcus aureus (MRSA). Our findings parallel the low recurrence rate following prosthetic repair. We have reported a higher than expected infection rate particularly with MRSA. Although repairs with Composix mesh are highly successful in regard to recurrence, the high infection rate and resulting morbidity needs to be further evaluated.

Nigrostriatal dopaminergic neurons release dopamine from dendrites in substantia nigra and axon terminals in striatum. The cellular mechanisms for somatodendritic and axonal dopamine release are similar, but somatodendritic and nerve terminal dopamine release may not always occur in parallel. The current studies used in vivo microdialysis to simultaneously measure changes in dendritic and nerve terminal dopamine efflux in substantia nigra and ipsilateral striatum respectively, following intranigral application of various drugs by reverse dialysis through the nigral probe. The serotonin releasers (+/-)-fenfluramine (100 micro m) and (+)-fenfluramine (100 micro m) significantly increased dendritic dopamine efflux without affecting extracellular dopamine in striatum. The non-selective serotonin receptor agonist 1-(m-chlorophenyl)-piperazine (100 micro m) elicited a similar pattern of dopamine release in substantia nigra and striatum. NMDA (33 micro m) produced an increase in nigral dopamine of a similar magnitude to mCPP or either fenfluramine drug. However, NMDA also induced a concurrent increase in striatal dopamine. The D2 agonist quinpirole (100 micro m) had a parallel inhibitory effect on dopamine release from dendritic and terminal sites as well. Taken together, these data suggest that serotonergic afferents to substantia nigra may evoke dendritic dopamine release through a mechanism that is uncoupled from the impulse-dependent control of nerve terminal dopamine release.

The purpose of this study was to examine the results of a single institution experience with hand-assisted laparoscopic colon resection for benign disease. We conducted a retrospective study of consecutive cases performed by experienced laparoscopic surgeons at a single institution. From August 1999 to June 2001, 37 patients underwent hand-assisted laparoscopic colon resection. Seventeen patients were male, and 20 were female. Median patient age was 58 years (range 20-80). Indications for surgery were: polyp (13), uncomplicated diverticular disease (eight), complicated diverticular disease (i.e., colovesicular fistula, phlegmon, etc.) (seven), chronic constipation (four), rectal prolapse (two), ulcerative colitis (one), endometriosis (one), and fecal incontinence (one). Procedures performed were: sigmoidectomy (14), right colectomy (nine), low anterior resection (seven), subtotal colectomy (five), cecectomy (one), and transverse colectomy (one). Variables examined were: conversion to open procedure, operative time, blood loss, time to return of flatus, length of postoperative hospital stay, and complications. There were no deaths. One case was converted to celiotomy (unable to rule out malignancy). The median operative time was 122 minutes (range 32-240) with a median operative blood loss of 132 mL (range 0-300). Return of flatus was noted (median) at postoperative day 3 (range 1-5), and the median length of stay after operation was 4 days (range 2-8). One patient developed a superficial wound infection, and there was one pelvic abscess (drained percutaneously). One patient developed urinary retention. There were no reoperations. In this single-institution experience hand-assisted laparoscopic elective colectomy for benign disease was successful in both straightforward and complicated cases. A low conversion rate to celiotomy and favorable operative times compared with published "pure" laparoscopic results suggest a flatter learning curve for handoscopy while retaining the benefits of "minimally invasive" surgery such as early return of flatus and short postoperative hospital stay. For these reasons hand-assisted laparoscopy should be considered an acceptable technique in elective colon resection for benign disease.

The regulation of dendritic dopamine release in the substantia nigra (SN) likely involves multiple mechanisms. GABA and glutamate inputs to nigrostriatal dopamine neurons exert powerful influences on dopamine neuron physiology; therefore, it is probable that GABA and glutamate likewise influence dendritic dopamine release, at least under some conditions. The present studies used in vivo microdialysis to determine the potential roles of nigral GABA and glutamate receptors in the regulation of dendritic dopamine release under normal conditions and when dopamine signaling in the basal ganglia is compromised after systemic haloperidol administration. Nigral application of the GABA(A) receptor antagonist bicuculline by reverse dialysis significantly increased spontaneous dopamine efflux in the SN. However, spontaneous dopamine efflux in the SN was not significantly affected by local application of the glutamate receptor antagonists 6-cyano-7-nitroquinoxaline-2,3-dione or (+/-)-3-[2-carboxypiperazine-4-yl]-propyl-1-phosphonic acid. Systemic haloperidol administration significantly increased the extracellular dopamine measured in the SN. Blockade of nigral GABA(A) receptors by local bicuculline application did not alter this effect of systemic haloperidol, despite the bicuculline-induced increase in spontaneous dendritic dopamine efflux. In contrast, nigral application of either glutamate receptor antagonist significantly attenuated the increases in dendritic dopamine efflux elicited by systemic haloperidol. These data suggest that under normal conditions, activity of GABA afferents to SN dopamine neurons is an important determinant of the spontaneous level of dendritic dopamine release. Circuit-level changes in the basal ganglia involving an increased glutamatergic drive to the SN appear to underlie the increase in dendritic dopamine release that occurs in response to systemic haloperidol administration.