Anesthetic experience with cardiac transplantation.

The anesthetic management of 17 patients undergoing cardiac transplantation is described. Recipients had severe biventricular failure and pulmonary hypertension. Careful administration of diazepam and morphine was the preferred induction method, and pancuronium was the favored relaxant for both intubation and maintenance. Sterile technique was used in placing endotracheal tubes. Relatively small doses of morphine and diazepam, combined with 50 percent nitrous oxide, were satisfactory for the maintenance of anesthesia. Postperfusion problems were few but included poor tolerance of hypovolemia and an exaggerated hypotensive response to protamine. Isoproterenol was required to support ventricular performance, but no other cardiac stimulants were needed. Postoperative courses were uneventful. There were no operative deaths and no recall of awareness during the operation with the described method of "light" anesthesia.

Respiratory acidosis with the small Storz-Hopkins bronchoscopes: occurrence and management.

Carbon dioxide retention in the Storz rigid ventilating bronchoscope with the Hopkins lens system was investigated in the laboratory. The 3.5, 4.0, and 5.0 30-cm Storz bronchoscopes with a 3.95-mm (outside diameter) telescope lens were used in 10 mongrel dogs weighing between 8 and 15 kg. Significant (p less than 0.01) accumulation of arterial carbon dioxide tension (PaCO2) (respiratory acidosis) was observed after 5 and 10 minutes of ventilation through the 3.5 and 4.0 bronchoscopes, but no significant increase in PaCO2 was noted with the 5.0 bronchoscope. There was no significant change in arterial oxygen tension under the same conditions. Manual compression of the upper anterior abdominal wall during expiration was applied during bronchoscopy in 6 children. Arterial blood samples were taken before insertion of the bronchoscope and 5 minutes later with and without abdominal compression during expiration. A significant increase (p less than 0.05) in PaCO2 and a decrease in pH were observed after 5 minutes of the bronchoscopic procedure without manual compression of the abdominal wall, while no significant changes in PaCO2 were observed with abdominal compression.

Decreasing frequency of anesthetic cardiac arrests.

STUDY OBJECTIVE: To determine whether the anesthetic cardiac arrest rate decreased following the introduction of enhanced respiratory monitoring and increased safety awareness during the past decade. DESIGN: Epidemiologic study of surgical anesthetic morbidity as represented by intraoperative cardiac arrests. SETTING: Operating room suite of a large university hospital. PATIENTS: 241,934 patients undergoing surgery over a period of 20 years. INTERVENTIONS: Anesthetic cardiac arrest rates from two decades were compared. The first decade (1969 to 1978) predated safety initiatives, while the second (1979 to 1988) included them. MEASUREMENTS AND MAIN RESULTS: Anesthetic cardiac arrests were identified, and their causes (respiratory vs nonrespiratory) and preventability (identifiable error) were determined shortly after their occurrence, as part of an ongoing study initiated in 1969. They provided numerators for rate calculations; total surgical anesthetics provided the denominators. The anesthetic cardiac arrest rate decreased by one-half from the first decade (2.1 arrests/10,000 anesthetics) to the second (1.0/10,000), a significant difference (p = 0.032, Fisher's Exact Test). The rate for preventable arrests due to respiratory causes declined significantly from 0.8/10,000 to 0.1/10,000 (p = 0.013) and accounted for most of the observed decrease in the overall anesthetic cardiac arrest rate. The rates for preventable nonrespiratory arrests and nonpreventable arrests did not change significantly. CONCLUSIONS: The results support the hypothesis that improved respiratory monitoring was effective in decreasing anesthetic morbidity.

How rebreathing anaesthetic systems control PaCO2: studies with a mechanical and a mathematical model.

Results from a proposed equation for rebreathing systems, (formula: see text), were compared with results from a mechanical model "lung" ventilated either with a Bain Breathing Circuit, or a circle system (Eger-Ethans type A) without soda lime. When values for carbon dioxide excretion (VCO2), dead spacetidal volume ratio (VD/VT), minute volume ventilation (VE), and fresh gas flow (VF) were varied over a wide range, the model and the equation yielded identical values of PaCO2. When VCO2 = 2.25 ml/kg, VD/VT = 0.5, and VE = 140 ml/kg, then fresh gas flows (VF) with both the equation and the model produced values of PaCO2 which were very close to those found by Bain and Spoerel in anaesthetized, artificially ventilated humans. It is concluded that the equation is an accurate mathematical representation of how rebreathing anaesthetic systems control PaCO2. It is expected that the equation will be useful in the clinical application of rebreathing anaesthetic systems, allowing the selection of minute volumes and fresh gas flows which will yield predictable PaCO2 values.

Cardiac arrest due to anesthesia. A study of incidence and causes.

Cardiac arrests due solely to anesthesia were studied in a large university hospital over a 15-year period. There were 27 cardiac arrests among 163,240 anesthetics given, for a 15-year incidence of 1.7 per 10,000 anesthetics. Fourteen of these patients (0.9 per 10,000) subsequently died. Detailed examination of the data from these 27 patients revealed that the pediatric age group had a threefold higher risk than adults, and that the risk for emergency patients was six times that for elective patients. Failure to provide adequate ventilation caused almost half of the anesthetic cardiac arrests, and one third resulted from absolute overdose of an inhalation agent. Hemodynamic instability in very ill patients was an association in 22%. Specific errors in anesthetic management could be identified in 75%. Progressive bradycardia preceding the arrest was observed in all but one case.

Resection of stenotic trachea: a case presentation.

Tracheal stenosis is usually a complication of prolonged mechanical ventilation. If the narrowing is severe it will greatly obstruct the air flow. Resection of the damaged trachea is a life saving procedure. The anesthetic management of the resection of an "ice cream cone narrowing" of the trachea (3 mm diameter) 4 cm above the carina is reported. A forced vital capacity loop (expiration-inspiration) of air flow versus volume revealed preoperatively little difference in the flow during the forced (F-V) and resting ventilation (Vt), thus confirming a diagnosis of severe upper airway obstruction. A total obstruction of the air flow was encountered during the skeletonization of the trachea and the surgeon was allowed to work for not more than 60 seconds at a time. Perfect cooperation between the surgeon and the anesthetsia team is necessary for the successful completion of this type of surgery.

Emergency medical technician (EMT-A) instruction of medical students.

In 1977 the Department of Anesthesiology of the Medical College of Virginia coordinated a compulsory 72-hour course for first-year medical students fulfilling all requirements of the Department of Transportation and leading to eligibility for certification of the medical student as an Emergency Medical Technician (EMT-A). We describe the methodology and content of this course, as well as problems encountered and lessons learned. This sound foundation in emergency care concepts will enable the medical student to develop greater competence in critical skills during the clinical years.

Is the Bain breathing circuit the future anesthesia system? An evaluation.

The Bain breathing circuit, a modified Mapleson D system, was evaluated with regard to oxygenation and CO2 elimination under controlled conditions and compared with the presently popular semiclosed breathing circuit (SCBC) with CO2 absorber. The authors demonstrated that the Bain system compares favorably with the SCBC in regard to oxygenation of manually ventilated patients with fresh gas inflow of 70 ml/kg/min while maintaining a PaCO2 at a mean of 38 torr versus an SCBC mean of 32 torr. The authors were impressed with the clinical simplicity, efficiency, and versatility of the Bain system and believe that it will play a major role in the future of anesthesia-machine design.

Mouth-to-mask ventilation: a superior method of rescue breathing.

Tidal volumes achieved using endotracheal intubation with a self-inflating bag were compared to those achieved with the esophageal obturator airway, a bag-valve mask system, and mouth-to-mask ventilation in an experimental model employing 18 unskilled and 4 partially skilled rescuers. When compared to mean tidal volumes achieved with endotracheal intubation (1,193 ml with unskilled, 942 ml with semi-skilled rescuers), ventilation with the bag-valve-mask system was significantly less (509 and 495 ml tidal volumes) and was, in fact, well below the value of 800 ml recommended for rescue breathing. Mouth-to-mask ventilation produced tidal volumes (1,093 ml and 1,200 ml) not significantly different from those seen with endotracheal intubation. If clinical findings confirm these experimental results, mouth-to-mask ventilation should replace the bag-valve-mask system in the initial management of respiratory arrest.