Donald E. Martin

Perioperative pulmonary embolism: diagnosis and anesthetic management

All perioperative patients, but especially trauma victims and those undergoing prostate or orthopedic surgery, are at increased risk of venous thromboembolism. Patients at highest risk include those with malignancy, immobility, and obesity; those who smoke; and those taking oral contraceptives, hormone replacement therapy, or antipsychotic medications. Dyspnea, anxiety, and tachypnea are the most common presenting symptoms in awake patients, and hypotension, tachycardia, hypoxemia, and decreased end-tidal CO(2) are the most common findings in patients receiving general anesthesia. The presence of shock and right ventricular failure are associated with adverse outcomes. Helical computed tomographic scanning is the preferred definitive diagnostic study, but transesophageal echocardiography may be valuable in making a presumptive diagnosis in the operating room. Early diagnosis allows supportive therapy and possible anticoagulation (in some cases, to be started before the conclusion of surgery).

Anesthetic management for cardiac transplantation in North America—1986 survey

Cardiac transplantation has become an established part of the therapy of end-stage heart disease. The number of cardiac transplants performed, as well as the number of centers performing them, has increased dramatically in the past 2 years. A paucity of literature on the anesthetic management of patients undergoing cardiac transplantation prompted this survey of 46 United States and Canadian institutions. The report summarizes the perioperative anesthetic management of a total of 1,273 transplant recipients in 34 institutions. Generally, similar anesthetic techniques and agents were used. One notable exception was the percentage of institutions using perioperative pulmonary artery catheter monitoring. As determined from this survey, right ventricular failure remains the leading cause of inability to terminate cardiopulmonary bypass in this patient population. Further, in surveyed institutions, cardiac transplantation expends more physician as well as hospital resources per patient than coronary artery bypass surgery.

Relevance of oral intake and necessity to void as ambulatory surgical discharge criteria

Discharge criteria used in the outpatient setting of a 500-bed academic medical center were evaluated by nursing staff in two ambulatory units to determine validity in identifying patient readiness for discharge. Criteria categories include temperature, circulation, activity and mental status, pain, bleeding, voiding, and oral intake. The hospital course and post-discharge course of a convenience sample of 248 ambulatory subjects was drawn from consecutive patients. Post-discharge recovery outcomes identified by the telephone assessment included recovery, complications, necessity of further medical treatment, and the need to return to a medical facility. The descriptive results showed the safety of the seven discharge criteria. Voiding and oral intake were related to prolonged stays in the ambulatory units. Approval was granted by the Hospital Policy Board to relax discharge criteria, and make voiding and oral intake optional for patients. A stage II follow-up study of 1,582 patient subjects was conducted using the new criteria of voluntary voiding and oral intake. The average ambulatory stay was reduced 50 minutes after voiding and oral intake were made optional.

Cardiopulmonary bypass interference with dantrolene prophylaxis of malignant hyperthermia

M ALIGNANT hyperthermia (MH) crisis in susceptible patients carries a high mortality rate, and can often be prevented by pretreatment with dantrolene sodium, l Cardiac surgery with cardiopulmonary bypass (CPB) for correction of congenital heart defects 2 or acquired heart disease 3 may present a particular risk to the MH-susceptible patient. First, dantrolene blood concentrations might decrease below effective prophylactic levels during CPB; and second, active rewarming causing regional hyperthermia during the latter phases of bypass could trigger an MH crisis. 4 While MH is rare, data relating to the management of CPB for susceptible patients are important, because immediate therapy with adequate doses of dantrolene can be lifesaving. 5 This paper reports serial blood dantrolene levels in an MH-susceptible child who underwent cardiac surgery with CPB. There appear to be no previous published reports of the effects of CPB on dantrolene pharmacokinetics. In addition, a study of whole-blood dantrolene levels during in vitro perfusion of a simulated patient was performed to further elucidate the changes in dantrolene pharmacokinetics that are caused by cardiopulmonary bypass.

STRATEGIES FOR THE PREOPERATIVE EVALUATION OF THE HYPERTENSIVE PATIENT

Because hypertension affects at least 50 million residents in the United States, 31,55 the detection, evaluation, and perioperative treatment of hypertension are common everyday clinical problems faced by the anesthesiologist. Hypertension affects the anesthesiologists choice of drugs, monitoring, and postoperative planning. Therefore, a basic understanding of the disease, its implications, and treatment is necessary for the care of the surgical patient. Part of the dilemma has been in defining what constitutes hypertension and what level of blood pressure requires intervention. Even more important from the standpoint of the anesthesiologist is at what level of hypertension and under what circumstances should further workup of the patient be completed before surgery. The article reviews current clinical knowledge and outlines a rational strategy for dealing with this recurring clinical problem.

Hemodynamic effects of muscle relaxant drugs during anesthetic induction in patients with mitral or aortic valvular heart disease

The hemodynamic effects of three nondepolarizing skeletal muscle relaxant drug regimens were compared during the induction of general anesthesia in 64 patients with valvular heart disease using a double-blind protocol. Patients were first stratified according to primary valvular defect (aortic stenosis, aortic regurgitation, mitral stenosis, or mitral regurgitation). Next, patients were randomly allocated to a drug group, either group A (atracurium), group V (vecuronium), or group MP (metocurine plus pancuronium). Data were collected during three periods: awake, postanesthetic induction, and posttracheal intubation. Four cardiovascular variables were designated a priori as primary variables of interest. These were heart rate (HR), mean arterial pressure (MAP), cardiac index (CI), and systemic vascular resistance index (SVRI). Patients with mitral stenosis showed two significant hemodynamic differences among muscle relaxant drug groups: (1) CI increased in group A but decreased in group MP between the awake and postinduction measurements (P = 0.032); and (2) SVRI decreased in group A but increased in group MP between the awake and postintubation periods (P = 0.034). In contrast, patients with aortic stenosis, aortic regurgitation, or mitral regurgitation demonstrated no statistically significant difference in cardiovascular responses among drug groups. Further analysis was performed using the following data: (1) other hemodynamic variables; (2) incidence of deviations from cardiovascular stability; and (3) the frequency of cardiovascular drug use. This examination showed no important differences among the muscle relaxant drug groups. The small but significant hemodynamic changes observed in mitral stenosis patients in drug groups A and MP were not noted with vecuronium.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of a standardized premedication on oxygen saturation in the cardiac patient before transfer to the operating room

The effect of premedication with morphine and scopolamine on arterial hemoglobin oxygen saturation (SaO2) was measured continuously in 26 undisturbed patients in their hospital rooms before coronary artery bypass surgery. Two hours preoperatively each patient received morphine, 0.1 mg/kg, and scopolamine, 0.2 or 0.4 mg. SaO2 was continuously recorded using pulse oximetry from one-half hour before premedication until 1 1/2 hours after premedication. The lowest SaO2 measured both the evening before surgery and one-half hour before premedication was 95% +/- 0.5% (mean +/- SEM). After administration of premedication, the lowest SaO2 for the patient population decreased to 93% +/- 0.4% (P less than 0.001 compared with that before premedication), and occurred 52 +/- 2 minutes after premedication was given. Two patients (8%) had an SaO2 less than 90% (lowest SaO2 for both was 88%). It is concluded that the dose of morphine/scopolamine premedication used was associated with a low risk of clinically important hypoxemia in the patient population studied.