Relationship of protamine dosing with postoperative complications of carotid endarterectomy.

Protamine sulfate (PS) neutralization of heparin (HEP) given during carotid endarterectomy (CEA) has been previously associated with an increased postoperative stroke rate. Dosing regimens of PS have varied in previous studies. The accuracy of PS dosing and its effect on postoperative complications was analyzed. The medical records of all patients undergoing elective CEAs from January 1993 to June 1996 in our institution were reviewed. A hematoma was defined as either an event requiring return to the operating room or when repeatedly identified in the medical record. The accuracy of dosing PS was determined utilizing a formula calculating the logarithmic exponential decay of HEP, which determined the residual HEP at the time of PS dosing. An ideal PS dose was then calculated and compared to the dose given. Statistical analyses was performed using a Fisher's exact test as well as the Student's t-test. Four hundred-seven CEAs were performed in 365 patients. There were 10/407 (2.5%) postoperative strokes (STROKE) and 11/407 (2.7%) hematomas, 3 of which required reoperation. Results indicate that (1) the administration of PS significantly reduced the incidence of postoperative hematoma; (2) there appears to be an association between the administration of PS and STROKE; (3) the inaccuracy in dosing PS appears to be based on a decision to dose PS to the total HEP given rather than the residual HEP on board at the time of neutralization. The effect of PS overdosing is unclear, but it may play a role in STROKE.

Perioperative predictors of colonic ischemia after ruptured abdominal aortic aneurysm.

PURPOSE: Colonic ischemia and colonic resection occur frequently after ruptured abdominal aortic aneurysm (rAAA). The purpose of this study was to identify the perioperative risk factors that might help to determine earlier in the postoperative period which patients are at risk for colonic ischemia and colonic resection. METHODS: The medical records of the 43 patients who underwent repair of rAAA from January 1989 to November 1997 were reviewed. The data were reviewed for the following factors: acidosis, pressor agents, lactate levels, guaiac status, cardiac index, coagulopathy, early postoperative bowel movement, the lowest intraoperative pH level, the temperature at the conclusion of the case, the location and duration of aortic cross clamping, the amount of fluid boluses administered after surgery, the amount of packed red blood cells administered during the case, and the average systolic blood pressure at admission and during surgery. Univariate analysis was performed with Fisher exact test, chi2 test, and Student t test. Multivariate analyses also were performed with the variables that were found to be significant on the univariate analysis. RESULTS: Thirteen of the 43 patients (30. 2%) had colonic ischemia, and seven of the 13 underwent colonic resection (53.8%). The overall mortality rate was 51.2% (22/43) five of the deaths were intraoperative and excluded from the study. In a comparison of the patients who had colonic ischemia with those who did not, statistically significant differences were found in the following variables: average systolic blood pressure at admission 90 mm Hg or less, hypotension of more than 30 minutes' duration, temperature less than 35 degreesC, pH less than 7.3, fluid boluses administered after surgery 5 L or more, and packed red blood cells 6 units or more. Multivariate analysis indicated that the number of these variables present correlated significantly with the positive predicted probability of colonic ischemia occurring. No patient with two factors or fewer had an ischemic bowel, and the positive predictive probability of colonic ischemia for those patients with six factors was 80%. CONCLUSION: The results of this study show that: (1) colonic ischemia after rAAA may be predicted with the presence of two or more specific perioperative factors, (2) the lack of a guaiac-positive bowel movement may be misleading for the early diagnosis of colonic ischemia, and (3) more than 50% of the patients with colonic ischemia will require a colonic resection. We recommend that any patient with rAAA with more than two perioperative factors undergo sigmoidoscopy every 12 hours after surgery for 48 hours to rule out colonic ischemia without waiting for early or guaiac-positive bowel movement.

Laparoscopically assisted abdominal aortic aneurysm repair: first 20 cases.

PURPOSE: Laparoscopic surgery decreases postoperative pain, shortens hospital stay, and returns patients to full functional status more quickly than open surgery for a variety of surgical procedures. This study was undertaken to evaluate laparoscopic techniques for application to abdominal aortic aneurysm (AAA) repair. METHODS: Twenty patients who had AAAs that required a tube graft underwent laparoscopically assisted AAA repair. The procedure consisted of transperitoneal laparoscopic dissection of the aneurysm neck and iliac vessels. A standard endoaneurysmorrhaphy was then performed through a minilaparotomy using the port sites for the aortic and iliac clamps. Data included operative times, duration of nasogastric suction, intensive care unit days, and postoperative hospital days. Pulmonary artery catheters and transesophageal echocardiography were used in seven patients. For these patients data included heart rate, pulmonary artery systolic and diastolic pressures, mean arterial pressure, central venous pressure, pulmonary capillary wedge pressure, cardiac index, and end diastolic area. Data were obtained before induction, during and after insufflation, during aortic cross-clamp, and at the end of the procedure. RESULTS: Laparoscopically assisted AAA repair was completed in 18 of 20 patients. Laparoscopic and total operative times were 1.44 +/- 0.44 and 4.1 +/- 0.92 hours, respectively. Duration of nasogastric suction was 1.3 +/- 0.7 days. Intensive care unit stay was 2.2 +/- 0.9 days. The mean length of hospital stay was 5.8 days excluding three patients who underwent other procedures. There were two minor complications, one major complication (colectomy after colon ischemia), and no deaths. For the eight patients who had intraoperative transesophageal echocardiographic monitoring, no changes were noted in heart rate, pulmonary artery systolic pressure, pulmonary capillary wedge pressure, and cardiac index. Pulmonary artery diastolic pressure and central venous pressure were greatest during insufflation without changes in end-diastolic area. Volume status, as reflected by end-diastolic area and pulmonary capillary wedge pressure, did not change. CONCLUSIONS: Laparoscopically assisted AAA repair is technically challenging but feasible. Potential advantages may be early removal of nasogastric suction, shorter intensive care unit and hospital stays, and prompt return to full functional status. The hemodynamic data obtained from the pulmonary artery catheter and transesophageal echocardiogram during pneumoperitoneum suggest that transesophageal echocardiography may be sufficient for evaluation of volume status along with the added benefit of detection of regional wall motion abnormalities and aortic insufficiency. Further refinement in technique and instrumentation will make total laparoscopic AAA repair a reality.

Utility of transesophageal echocardiography and pulmonary artery catheterization during laparoscopic assisted abdominal aortic aneurysm repair.

BACKGROUND: Advanced laparoscopic procedures are more commonly performed in elderly patients with cardiac disease. There has been limited data on the use of pulmonary artery catheters (PAC) and transesophageal echocardiography (TEE) to monitor hemodynamic changes. METHODS: We prospectively studied eight patients undergoing laparoscopic assisted abdominal aortic aneurysm repair. All patients had a PAC and all but one had an intraoperative TEE. Data included heart rate (HR), temperature (temp), pulmonary artery systolic (PAS) and diastolic (PAD) pressures, mean arterial pressure (MAP), central venous pressure (CVP), pulmonary capillary wedge pressure (PCWP), cardiac index (CI), mixed venous oxygen saturation (MVO2), and oxygen extraction ratio (O2Ex) and was obtained prior to induction, during insufflation, after desufflation, during aortic cross-clamp, and at the end of the procedure. End diastolic area (EDA), a reflection of volume status, was measured on TEE. ANOVA was used for data analysis. RESULTS: No changes were noted in HR, temp, PAS, PCWP, CI, MVO2, and O2Ex. PAD and CVP were greater during insufflation compared with baseline and aortic cross-clamp without associated changes in EDA. MAP was higher at baseline compared with all other times during the procedure. CONCLUSIONS: Insufflation increased PAD and CVP. However, volume status as suggested by EDA and PCWP did not change. These data question the reliability of hemodynamic measurements obtained from the PAC during pneumoperitoneum and suggest that TEE may be sufficient for evaluation of volume status along with the added benefit of timely detection of ventricular wall motion abnormalities.

Factors that affect the survival rate of patients with ruptured abdominal aortic aneurysms.

PURPOSE: There has been much discussion in the literature of factors that affect the mortality rate of patients who undergo repair of ruptured abdominal aortic aneurysms. Some studies have suggested restricting patient selection for repair on the basis of certain preoperative factors including age, increased creatinine level, low hemoglobin level, loss of consciousness, electrocardiographic changes, and preoperative cormorbid medical conditions. A retrospective review of 96 patients who underwent repair of a ruptured abdominal aortic aneurysm was performed to determine whether these factors would necessarily be applicable to all populations. METHODS: A retrospective chart review of all patients who underwent repair of a ruptured abdominal aortic aneurysm was performed over a study period of 20 years. Data was analyzed by both univariate and multivariate analysis. RESULTS: The mean age of the patients was 73 years. The intraoperative mortality rate was 23%. The in-hospital mortality rate was 60.4%, with a 30-day mortality rate of 56.3%. By univariate analysis of various factors associated with the mortality rate, hemoglobin level, creatinine level, lowest preoperative and average intraoperative systolic blood pressure, packed red blood cells transfused, estimated blood loss, intraoperative urine output, and temperature were statistically significant. A history of loss of consciousness was also statistically significant. No preoperative comorbid medical conditions were significant, nor was age. On a multivariate analysis, preoperative factors of loss of consciousness, a lowest preoperative systolic blood pressure less than 90 mm Hg, a hemoglobin level less than 10 g/dl, and a creatinine level greater than 1.5 mg/dl were predictive of death. The effects of the hemoglobin level, creatinine level, and loss of consciousness on the mortality rate were strongest in patients who had a lowest preoperative systolic blood pressure greater than 90 mm Hg. In patients who had the sets of preoperative factors that were associated with a 100% mortality rate, there were intraoprative factors that influenced their death. CONCLUSIONS: These findings suggest that the factors (loss of consciousness, creatinine level, hemoglobin level) that are predictive of death may be a reflection of shock in this patient population. Further studies should be directed to optimizing preoperative resuscitation. Patients who have a ruptured abdominal aortic aneurysm should not be denied therapy on the basis of any specific set of preoperative factors.