An innovative course in surgical critical care for second-year medical students.

PURPOSE: To assess students' learning and other aspects of an innovative elective (based on contextual learning) in surgical critical care for second-year medical students. METHOD: In 1990-91, 13 second-year students at the University of Colorado School of Medicine took a 12-week elective in surgical critical care. The elective required the students to be on night call four times in the surgical intensive care units of two university-affiliated hospitals, where they were supervised by second-year surgical residents and collected information about patients. Weekly tutorial sessions were held for case presentations by the students and for lectures by attending surgeons on pertinent clinical entities. At the conclusion of the course, the students took a shelf test from the Society of Critical Care Medicine. RESULTS: All 13 students scored above 70% on the shelf test, a passing grade for the Additional Qualifications in Critical Care. CONCLUSION: That the students passed an examination at the level of the Additional Qualifications in Critical Care without completing a surgical residency, let alone a critical care fellowship, suggests that contextual learning (where the clinical problem is presented initially and is then followed by self-directed study and group discussion) would prove highly effective in medical education. Students would enter clinical clerkships more prepared than presently if clinical skills were introduced contextually into the basic science curriculum.

Are modified radical mastectomies done for T1 breast cancers because of surgeon's advice or patient's choice?

Clinical trials show that T1 breast cancers are equally well treated with breast-conserving surgery as with modified radical mastectomy. However, the Colorado Central Cancer Registry indicates that, for the past 5 years, the majority of women (72%) with T1 breast cancer in Colorado have undergone modified radical mastectomies. A questionnaire was sent to 175 general surgeons to determine the reasons for the high number of modified radical mastectomies still being performed. The results indicate that one group of surgeons (34% of those responding) believes each type of surgery has equal survival rates but unknowingly influences the patient to choose modified radical mastectomy, with a subtly biased presentation. Education of both surgeons and patients is needed to increase the number of patients with T1 breast lesions who can benefit from breast-conserving therapy.

A unified approach to the torn thoracic aorta.

In a 3-year experience treating 12 patients with blunt torn thoracic aorta, the repair technique was "clamp and sew" with an intraluminal graft in the initial six patients and partial left heart bypass using a centrifugal pump in the more recently treated six. Patients in the two groups were similar in regard to age, sex, and injury severity score. In the intraluminal graft group, graft insertion was abandoned for sutured anastomosis in two patients. Two patients sustained spinal cord ischemia, and two developed hypertension due to "pseudo-coarctation" syndrome. Because of these side effects related to the performance of intraluminal graft, partial left heart bypass was adopted as our routine procedure and was successful in all subsequent patients. Based on our experience and on reports in the current literature, we recommend left atrial-femoral bypass with the centrifugal pump for repair of the torn thoracic aorta.

Gut bacterial translocation via the portal vein: a clinical perspective with major torso trauma.

Animal studies implicate gut bacterial translocation via the portal vein as a major factor in the pathogenesis of postinjury multiple organ failure (MOF). We therefore inserted portal vein catheters for sequential blood sampling in the operating room, at 6, 12, 24, and 48 hours, and 5 days postoperatively in 20 injured patients (13 blunt, seven penetrating; mean age, 34 years) requiring emergent laparotomy and who were at known risk for MOF. The mean Revised Trauma Score was 6.4 +/- 0.4, and the Injury Severity Score, 29.3 +/- 2.3. Twelve (60%) patients arrived in shock (SBP less than 90 torr). Eight (2%) of 212 portal blood cultures were positive; seven were presumed contaminants. The only positive systemic culture (total, 212) was a Staphylococcus aureus on day 5 in a patient with a concurrent staphyloccal pneumonia. In the first 48 hours, we could not detect endotoxin in portal or systemic blood. Additionally, simultaneous portal and systemic blood levels of complement fragment C3a, tumor necrosis factor, and interleukin-6 were nearly identical and, specifically, were not different in those patients who developed MOF. In summary, this prospective clinical study has not confirmed portal or systemic bacteremia within the first 5 days postinjury, despite an eventual 30% incidence of MOF.

Hypoxic events in the surgical intensive care unit.

An oxygen-monitoring protocol was established in the surgical intensive care unit (SICU) at the Denver General Hospital in July 1988. A 3-month surveillance audit ending March 1989 prospectively documented 100 consecutive hypoxic events in 51 of 241 (21%) SICU patients. These episodes occurred during mechanical ventilation in 46 patients, during spontaneous ventilation in 15 patients with artificial airways, and the remaining 39 occurred in nonintubated patients. Hypoxemia was recognized by pulse oximetry in 59, arterial blood gas analysis in 24, mixed venous oximetry in 15, and transcutaneous oxygen monitoring in 2. These events were due to problems with the ventilator or airway in 42, recent interventions in 21, new pulmonary process in 19, progression of underlying disease in 11, and unknown causes in 7. Two thirds resulted from mechanical problems amenable to simple intervention; there were two adverse outcomes. In conclusion, acute hypoxia is a frequent potentially morbid SICU event. Advances in continuous oxygen monitoring permit early identification and thereby may limit adverse outcomes, but should not prompt an expensive diagnostic work-up.

Auto-PEEP in the multisystem injured patient: an elusive complication.

Auto-PEEP (A-PEEP), unrecognized alveolar positive and expiratory pressure during mechanical ventilation, is an acknowledged hazard in patients with chronic obstructive lung disease. We evaluated 50 consecutive trauma patients for the presence of A-PEEP and its effect on hemodynamic stability. Injury Severity Scores (ISS) were 8 to 41 (21 +/- 1); Revised Trauma Scores (RTS) ranged from 2.0 to 7.8 (6.2 +/- 0.2). Mode of ventilation was assist control, inspiratory flow rates were 40 to 120 L/M (78 +/- 2). A-PEEP, determined in the non-assisting patient by occluding the expiratory port at end exhalation, was present in 28 patients (56%) and ranged from 1 to 12 cm H2O (5.3 +/- 0.4 cm H2O). Data segregated by A-PEEP versus no A-PEEP were as follows (Mean +/- SEM): [table: see text] *P less than 0.05, VE = minute ventilation, Paw = mean airway pressure. Upon reversal of A-PEEP in the eight patients with levels greater than 5 cm H2O, mean blood pressure rose from 90 +/- 17 to 102 +/- 22 mm Hg and central venous pressure fell from 13 +/- 5 to 7 +/- 5 mm Hg. A-PEEP was successfully treated in these eight patients by increasing peak flows, minimizing VE requirements and selective use of bronchodilators. In sum, the hypermetabolic ventilated trauma patient should be monitored routinely for this common phenomenon which may have profound cardiopulmonary effects in the setting of acute resuscitation.

The management of ruptured abdominal aortic aneurysms in rural Colorado. With a historical note on Kit Carson's death.

Kit Carson died of a ruptured aneurysm in rural Colorado in 1868. Since that time, techniques for management of aortic aneurysms have been developed and disseminated to rural areas with small hospitals. A survey of six Colorado rural hospitals' experience with ruptured abdominal aortic aneurysms is presented. Fifty-seven ruptured aneurysms had been managed during periods ranging from three to ten years. The average time to the operating room was 3.5 to 4.0 hours after hospital arrival and less than 45 minutes after diagnosis. Of those cases arriving with a systolic blood pressure less than 100 mm Hg, the mortality was 56%. The overall mortality was 53%. Groups are analyzed according to preoperative delay, occurrence of shock, and other risk factors. The results are compared with several series from metropolitan hospitals. Techniques of management that are of potential benefit in low-volume vascular case settings are discussed.

Massive air emboli from intravenous infusion pump: etiology and prevention.

A case of massive air embolus secondary to use of an intravenous infusion pump is presented. The pump is unable to detect air entering the intravenous line if the air enters distal to the air detection device. A simple solution is presented.