Robot-assisted minimally invasive Kasai portoenterostomy: a survival porcine study.

BACKGROUND: Major enhancements offered by robotic surgery for minimally invasive procedure include tremor filtration, motion scaling, and the addition of a wrist to the instrument. Minor enhancements include indexing as well as safe and rapid instrument exchange. A benefit associated with any endoscopic procedure is magnification. It was hypothesized that these enhancements would allow the performance of complex gastrointestinal surgery. METHODS: Eight survival pigs (weight, 2.5-8 kg) underwent a robotically assisted minimally invasive portoenterostomy. The procedure was analogous to the Kasai portoenterostomy for biliary atresia usually performed for human patients at the age of 4 to 12 weeks. RESULTS: Five of the eight animals survived for more than 1 month after the operation, returning to normal eating and bowel habits in 2 to 3 days. None were jaundiced. All laboratory values were normal. At 1 month, the animals were killed. There was no anastomotic stenosis at either the end-to-side enteroenterostomy or the portoenterostomy. Histologically, the anastomoses were well healed. CONCLUSION: Computer-assisted robot-enhanced technology allows complex gastrointestinal surgery to be performed using minimally invasive techniques.

Three quantitative approaches to the diagnosis of abdominal pain in children: practical applications of decision theory.

BACKGROUND/PURPOSE: The authors compared 3 quantitative methods for assisting clinicians in the differential diagnosis of abdominal pain in children, where the most common important endpoint is whether the patient has appendicitis. Pretest probability in different age and sex groups were determined to perform Bayesian analysis, binary logistic regression was used to determine which variables were statistically significantly likely to contribute to a diagnosis, and recursive partitioning was used to build decision trees with quantitative endpoints. METHODS: The records of all children (1,208) seen at a large urban emergency department (ED) with a chief complaint of abdominal pain were immediately reviewed retrospectively (24 to 72 hours after the encounter). Attempts were made to contact all the patients' families to determine an accurate final diagnosis. A total of 1,008 (83%) families were contacted. Data were analyzed by calculation of the posttest probability, recursive partitioning, and binary logistic regression. RESULTS: In all groups the most common diagnosis was abdominal pain (ICD-9 Code 789). After this, however, the order of the most common final diagnoses for abdominal pain varied significantly. The entire group had a pretest probability of appendicitis of 0.06. This varied with age and sex from 0.02 in boys 2 to 5 years old to 0.16 in boys older than 12 years. In boys age 5 to 12, recursive partitioning and binary logistic regression agreed on guarding and anorexia as important variables. Guarding and tenderness were important in girls age 5 to 12. In boys age greater than 12, both agreed on guarding and anorexia. Using sensitivities and specificities from the literature, computed tomography improved the posttest probability for the group from.06 to.33; ultrasound improved it from.06 to.48; and barium enema improved it from.06 to.58. CONCLUSIONS: Knowing the pretest probabilities in a specific population allows the physician to evaluate the likely diagnoses first. Other quantitative methods can help judge how much importance a certain criterion should have in the decision making and how much a particular test is likely to influence the probability of a correct diagnosis. It now should be possible to make these sophisticated quantitative methods readily available to clinicians via the computer.

Bile duct size does not predict success of portoenterostomy for biliary atresia.

BACKGROUND/PURPOSE: Presence of large bile ducts (>200 microm) at the portal end-plate has been suggested to predict success after portoenterostomy. The authors reviewed their patients with biliary atresia to test the hypothesis that bile duct size in patients with successful portoenterostomy was no different than in the patients with unsuccessful portoenterostomy. METHODS: The authors reviewed the patients at their institution from 1989 to 1998 who had the diagnosis of biliary atresia (n = 38). A pathologist blinded to the results of the operation confirmed the measurements of the bile duct remnants. RESULTS: Five of the 38 patients did not have a portoenterostomy. They underwent cholangiogram and liver biopsy and were evaluated for liver transplantation. All patients who underwent surgery (n = 33) had a Roux-en-y hepaticojejunostomy. Twenty-one patients had successful surgery (64%) and 12 patients (36%) had unsuccessful surgery. The average age at operation in the successful group was 50.9 +/- 3 days and in failures, 57.9 +/- 4 days (P = .16). Duct size at the portal end-plate was not different between the successes and failures. Two of the patients in the success group had no evidence of bile ducts grossly or histologically. CONCLUSION: Children presenting early in infancy (<3 months) with biliary atresia should undergo a portoenterostomy regardless of the size of the bile ducts at the time of exploration.

Predicting survival after coronary revascularization for ischemic cardiomyopathy.

BACKGROUND: The success of coronary revascularization for ischemic cardiomyopathy (left ventricular ejection fraction of 0.25 or less) has been unpredictable. We and others have demonstrated that the hospital operative mortality rate for these operations has been surprisingly low, particularly if evidence of ischemia is present. We subsequently liberalized our selection criteria based on our hypothesis that coronary artery bypass grafting is safe in this subset of patients regardless of the status of their distal coronary vasculature. METHODS: To examine this hypothesis, we studied retrospectively our patients undergoing coronary artery bypass grafting from 1983 to 1993. Ninety-six patients with ejection fractions of 0.25 or lower underwent this operation, with 88 hospital survivors (mortality 8%). All of the patients had clinical symptoms of heart failure. The male to female ratio was 4.6:1. The average age was 63.1 +/- 0.9 years (mean +/- standard error of the mean). Patients were excluded if they had valvular heart disease other than mild to moderate mitral regurgitation, required resection of a ventricular aneurysm, or required an emergency operation for acute coronary occlusion. Possible predictors of death were examined retrospectively. The catheterization films were reviewed retrospectively by a cardiovascular surgeon who was blinded to patient outcome and was never involved in the clinical management of any of the patients. Vessel quality was described as good, fair, or poor. RESULTS: Increased age and poor vessel quality were the only significant predictors of poor outcome. Sex, presence or absence of angina, preoperative angina, preoperative ejection fraction, preoperative arrhythmia disorder, aortic cross-clamp time, and the number of bypass grafts had no significant effect on outcome in the perioperative period. CONCLUSION: These results demonstrate that poor vessel quality and older age are predictors of poor outcome in patients with low ejection fractions undergoing myocardial revascularization. We conclude that poor distal coronary vasculature is a contraindication to coronary artery bypass grafting in patients with an ejection fraction of 0.25 or less, even if angina is present.

Pulmonary function after non-heart-beating lung donation in a survival model.

BACKGROUND: Lung procurement from recently deceased cadavers has been suggested to enlarge the limited donor pool. We hypothesized that lungs harvested from non-heart-beating donors (NHBD) would function as well as those harvested from heart-beating donors. METHODS: Sixteen adult swine underwent left lung allotransplantation. Controls received lungs procured from heart-beating donors, NHBD pigs received lungs immediately harvested from donors after death from asphyxiation, and NHBD-15 and NHBD-30 pigs received lungs harvested after 15 and 30 minutes after asphyxiation. RESULTS: After 1 week of survival, mean dynamic airway compliance (mL/cm H2O +/- standard error of the mean) was 16.3 +/- 0.7 in controls, and 17.3 +/- 1.0, 16.4 +/- 6.0, and 7.3 +/- 1.6 in the NHBD, NHBD-15, and NHBD-30 groups, respectively (p = 0.02, NHBD-30 versus others combined). No significant differences were noted in the pulmonary venous partial pressure of oxygen or pulmonary vascular hemodynamics compared with controls. CONCLUSIONS: The decrease in airway compliance noted in the NHBD-30 group may reflect an exacerbation of reperfusion injury caused by 30 minutes of warm ischemia during organ retrieval. We conclude that posttransplantation lung function using an NHBD with up to 15 minutes of warm ischemia is equivalent to lung function after heart-beating harvest.

Prevention of spinal cord injury after repair of the thoracic or thoracoabdominal aorta.

Spinal cord injury occurring as the result of surgical repair of thoracic and thoracoabdominal aortic disease remains a devastating complication. The incidence of postoperative neurologic deficits varies from 4% to 38%. Factors associated with a greater risk for injury include the presence of dissection or extensive thoracoabdominal disease, and a prolonged cross-clamp time. Spinal cord ischemia initiates a deleterious cascade of biochemical events that ultimately result in an increased intracellular calcium concentration. Calcium-activated proteases, lipases, and nucleases mediate the processes that cause cell injury. The accumulation of oxygen-derived free radicals and the occurrence of hyperemia during reperfusion are also contributing causes of spinal cord injury. Increasing the spinal cord blood flow with shunts, oxygenated bypass circuits, cerebrospinal fluid drainage, the intrathecal administration of vasodilators, and the reattachment of intercostal arteries has been tried in an effort to increase spinal cord perfusion. Pharmacologically based measures to prevent spinal cord injury have been pursued, and these have consisted of hypothermia, anesthetic agents, calcium channel blockers, free radical scavengers, and immune system modulation. However, no single technique has proved to be consistently effective in preventing ischemia-induced spinal cord injury.

Compensatory growth of porcine right lungs after chronic rejection of transplanted left lungs.

Neonatal lung hypoplasia is frequently a fatal condition often associated with congenital diaphragmatic hernia. Unilateral lung transplantation rarely has been performed for this indication, although it is a potential solution. It is not known whether the transplant needs to function permanently or to act as a bridge until the native lung develops. It is also not known whether the native lung will grow in the face of an immunosuppressed state and chronic rejection of the transplanted lung. We therefore developed a porcine model of left lung rejection to study this. Infant swine underwent left lung transplantation. Chronic rejection occurred in all, resulting in nonfunction of the transplanted lung. The right lungs of these animals were compared with the right lungs of size-matched and age-matched control animals not given immunosuppressive treatment and not undergoing transplantation. There were no differences in terms of the functional residual capacity, airway compliance, and airway resistance among the groups. There was a significant increase in the pulmonary vascular resistance in the animals with transplanted lungs. There was also a significant increase in the lung weight in these animals. Unilateral pneumonectomies were done in 4 infant pigs to serve as controls. Three of the 4 did not survive the operation because of acute pulmonary failure. In conclusion, the study group exhibited evidence of compensatory growth that was not seen in the control animals, as shown by the increase in lung weight. This suggests that contralateral lung growth occurs in a growing animal, despite the effects of immunosuppression therapy and chronic rejection of the transplanted lung.

Ambulatory intraaortic balloon counterpulsation.

A technique is described for the retroperitoneal placement of a balloon pump that preserves patient mobility. This technique may be superior to standard femoral placement when prolonged support is required for cardiac transplant candidates awaiting donor organs.

Management of renal tumors involving the inferior vena cava.

PURPOSE: We reviewed our experience of the resection of renal tumors involving the inferior vena cava (IVC) from 1987 to 1992 with the hypothesis that retrohepatic IVC involvement of renal tumors can be managed without cardiopulmonary bypass (CPB) and circulatory arrest with acceptable morbidity and mortality rates. METHODS: We retrospectively reviewed our experience of radical nephrectomies for renal tumors from 1987 to 1992 (n = 69). Of these, 13 had involvement of the IVC (19%). Three of the patients had right atrial extension requiring CPB with circulatory arrest. Three patients had retrohepatic involvement, and seven had infrahepatic involvement. All thirteen patients underwent operative removal of the tumor and tumor thrombus. RESULTS: The patients with atrial extension who were treated with CPB and circulatory arrest had hospital and 1-year survival rates of 100% (three of three). The patients with retrohepatic extension treated without CPB and circulatory arrest had hospital and 1-year survival rates of 100% (three of three). The patients with infrahepatic extension treated without CPB and circulatory arrest had hospital and 1-year survival rates of 85% (six of seven) and 50% (three of six), respectively. There was no statistically significant difference between groups. The hospital death occurred in a patient who had a massive pulmonary embolism and disseminated intravascular coagulation before operation. The deaths that occurred before 1 year were due to metastatic disease and unresectable disease at the time of operation. CONCLUSION: CPB with circulatory arrest is not required in patients with retrohepatic IVC extension of renal tumors, and aggressive resection can be performed in these patients with acceptable morbidity and mortality rates.

Successful use of undersized donors for orthotopic heart transplantation--with a caveat.

Accepted clinical practice has been to require body weights to be within 20% as a criterion for matching donor to recipient for cardiac transplantation. From November 1989 through September 1993 we began accepting larger differences in body weight between donor and recipient with 80 orthotopic heart transplants performed. Twenty-eight of these transplants used undersized donors (donor-to-recipient body weight ratio [DRBW] of 0.6 to 0.8) with the remaining donors being either size matched (DRBW = 0.8 to 1.0) or oversized (DRBW > 1.0). Thirty-three of the 80 transplant recipients (41%) were classified preoperatively as United Network for Organ Sharing (UNOS) status I and the remaining patients were classified as UNOS status II. Hospital survival for status I recipients was 9 of 14 (64%) for undersized donors, 7 of 8 (87.5%) for sized-matched donors, and 11 of 11 (100%) for oversized donors (p < 0.05). Hospital survival for status II recipients was 12 of 14 (85.7%) for undersized donors, 24 of 24 (100%) for sized-matched donors, and 8 of 9 (88.8%) for oversized donors. Our data support the continued use of hearts from undersized donors in status II recipients. The use of hearts from undersized donors in status I recipients is associated with increased mortality compared with size-matched donors and must be undertaken with caution.

Optimal timing of abdominal aortic aneurysm repair after coronary artery revascularization.

OBJECTIVE: The authors ascertained the optimal timing of repair of an abdominal aortic aneurysm (AAA) after coronary artery revascularization. SUMMARY BACKGROUND DATA: Cardiac events are the most common cause of death after elective repair of AAA. Preoperative coronary revascularization has significantly reduced postoperative cardiac complications after elective AAA repair. Currently, most patients undergo repair of asymptomatic AAA within 6 months after the coronary revascularization. METHODS: The authors performed a retrospective review of patients who underwent repair or scheduled repair of an asymptomatic AAA within 6 months after coronary artery bypass graft (CABG) between March 1988 and October 1993. RESULTS: There was no mortality in the group of patients (n = 14) who underwent repair of AAA simultaneously or within 14 days of coronary revascularization. In contrast, there was a significantly increased mortality rate of 3 of 9 (33%) in patients scheduled to undergo repair of the AAA more than 2 weeks after coronary revascularization (p < 0.05). All nonsurvivors died between 16 and 29 days after CABG, and died as a result of ruptured AAA. CONCLUSION: Elective AAA repair should be undertaken simultaneously or within 2 weeks of coronary artery revascularization because of an increased risk of postoperative AAA rupture seen after this time period. In addition, simultaneous or early postoperative AAA repair does not increase the overall operative risk.

Complete prevention of postischemic spinal cord injury by means of regional infusion with hypothermic saline and adenosine.

Spinal cord injury after operations on the descending thoracic and thoracoabdominal aorta remains a persistent clinical problem. Previous attempts to decrease the risk of this devastating complication by lowering the rate of metabolism of the spinal cord have met with varying success. We hypothesized that the tolerance of the spinal cord to an ischemic insult could be improved by means of adenosine. Twenty New Zealand white rabbits underwent 40 minutes of isolated infrarenal aortic occlusion after heparin anticoagulation. Clamps were placed both below the left renal vein and above the aortic bifurcation. In 10 rabbits (group A), a bolus of adenosine (100 mg) was infused into the isolated aortic segment immediately after crossclamping and this bolus was followed by a flush of hypothermic saline (8 degrees C, 30 ml/kg) over the first 10 minutes of ischemia. In one control group of five animals (group B), the descending infrarenal aorta was crossclamped without infusion of adenosine or saline. In another control group of five animals (group C), the aortic segment was flushed with normothermic saline (37 degrees C) in a fashion identical to that of the study group. The aortic clamps were removed after 40 minutes, the abdomen was closed, and the animals were allowed to recover from anesthesia. Spinal cord function was assessed 12, 24, 48, 72, and 96 hours after operation by the Tarlov scale. All animals were put to death at 96 hours after operation and spinal cords were harvested for histologic analysis. The spinal cord function of all group A animals was fully intact with Tarlov scores of 5; group B and group C animals were all paraplegic with Tarlov scores of 0 (p < 0.001, general linear models analysis of variance). Histologic examination of spinal cords from group A rabbits revealed no evidence of cord injury, whereas spinal cords from groups B and C had evidence of extensive cord injury with central gray necrosis, axonal swelling, dissolution of Nissl substance, and astrocyte and macrophage infiltration. Regional infusion of the crossclamped infrarenal rabbit aorta with hypothermic saline and adenosine completely prevented paraplegia in our model despite a 40-minute ischemic insult.