Unanticipated admission to the hospital following ambulatory surgery.

We conducted a case-control study to identify clinical and demographic risk factors for admission to the hospital following ambulatory surgery. Of 9616 adult patients who underwent ambulatory surgery at a university-affiliated hospital between 1984 and 1986, one hundred were admitted. The most common reasons for admission were pain (18), excessive bleeding (18), and intractable vomiting (17). The mean age (+/- SD) of patients who were admitted was 37 +/- 13 years, and 96% had American Society of Anesthesiologists' physical status scores of 1 or 2. Factors that were independently associated with an increased likelihood of admission were general anesthesia (odds ratio, 5.2), postoperative emesis (odds ratio, 3.0), lower abdominal and urologic surgery (odds ratio, 2.9), time in the operating room greater than 1 hour (odds ratio, 2.7), and age (odds ratio, 2.6). Our results indicate that the likelihood of unanticipated admission is related more to the type of anesthesia and surgical procedure rather than to the patient's clinical characteristics.

Hospital resources used for inpatient and ambulatory surgery.

New hospital and physician payment schemes encourage physicians to participate actively in efforts to minimize hospital resource use. As an example of the type of evaluations anesthesiologists may conduct, we examined hospital resources used for comparable groups of inpatients (INPTs) and day surgery unit (DSU) patients. Although INPTs and DSU patients undergoing surgical arthroscopy of the knee or diagnostic laparoscopy were similar with regard to age, physical status, and staff surgeon, more preoperative tests were performed for INPTs than for DSU patients (P less than .05). Hospital costs for these tests were four times greater for INPTs than for DSU patients. Operating room time was from 20 to 45 min longer for INPTs than for DSU patients (P less than .05). Recovery room time was from 25 to 52 min longer for DSU patients (P less than .05). Per patient nursing labor costs paralleled operating and recovery room times. These kinds of analyses are important in identifying opportunities to improve resource use, in assessing institutional costs for surgical care, and in designing strategies that allow institutions and physicians to respond to cost containment pressures.

A departmental policy addressing chemical substance abuse.

Substance abuse is a major socioeconomic problem. However, the ready availability of potent narcotic and sedative drugs probably constitutes a unique risk for anesthesiologists. Until recently, few anesthesia departments were prepared to recognize or safely manage afflicted colleagues. Because we felt it important to educate our staff and residents and to have a response mechanism established prior to the advent of a substance abuse problem, a departmental committee was formed to develop a Substance Abuse Policy. The policy has served to increase our general awareness and to direct our actions effectively when dealing with physician impairment. It is presented here in the belief that other departments might find it useful in tailoring their approach to this problem.

The mechanical aspects of anesthetic pollution control.

Reduction of anesthetic contamination in the operating room requires removal of excess circuit gases (scavenging), elimination of anesthetic equipment leakage, and avoidance of anesthetic technics which allow unopposed spill of gas into the operating room. Scavenging and disposal of excess anesthetic gases can present hazards to the patient; means to protect the breathing circuit from elevated positive and negative pressures should be of prime consideration in selecting a scavenging system. Leakage from anesthic equipment occurs in the high-pressure (central and tank N2O sources to the machine flowmeters) and the low-pressure portions (from the machine flow-meters to the patient) of the system and can be of sufficient magnitude to virtually negate effective scavenging. These leakage points can be readily detected and corrected using periodic simple test procedures.

Cerebral blood flow and metabolism during morphine--nitrous oxide anesthesia in man.

The effects of two levels of morphine-nitrous oxide anesthesia on cerebral blood flow (CBF) and cerebral metabolism (CMRO2) were measured in healthy male volunteers. CBF and metabolic measurements were made in the awake control state, after morphine, 1 mg/kg, with 70 per cent nitrous oxide and 30 per cent oxygen, and at a total dose of 3 mg/kg morphine with the same concentrations of nitrous oxide and oxygen. Ventilation was controlled and carbon dioxide added to inspired gas to maintain PaCO2 constant at 40 torr. CBF was 48.2 +/- 4.4 (SEM) ml/100 g/min during the control phase; 45.7 +/- 6.4 ml/100 g/min after 1 mg/kg morphine, and 44.3 +/- 4.9 ml/100 g/min after 3 mg/kg morphine. The latter values are not significantly different from control. Cerebral metabolic rates for oxygen, glucose, and lactate were normal in the control phase and did not change significantly when morphine was present at either level. It is concluded that morphine-nitrous oxide anesthesia produces no alteration of cerebral blood flow or metabolism in normal man at the two dose levels studies.

Hypocalcaemia during rapid blood transfusion in anaesthetized man.

In anaesthetized patients, administration of citrated whole blood for 5 min at controlled rates of 50, 100 and 150 ml/70 kg/min resulted in decreases in the calcium ion concentration (Ca2+) of 14, 31 and 41%, respectively. Ca2+ returned rapidly to the control values after termination of the transfusion. Reciprocal changes in serum citrate concentrations occurred, suggesting that the transient hypocalcaemia was a result of redistribution of citrate and hepatic or renal clearance from the vascular space. The total serum calcium concentration did not change significantly during rapid blood administration. Normal saline infusion at 100 ml/70 kg/min caused no change in Ca2+; however, plasma protein administration at this rate resulted in an 18% decrease in Ca2+, presumably as a consequence of the binding of calcium ions to anionic sites on plasma protein. Hypocalcaemia accompanying blood transfusion is a transient phenomenon, dependent on the total dose of citrate administered and the rate of infusion. Rational calcium replacement therapy during massive blood transfusion may now be based on direct Ca+ measurement.

Anesthesia and the immune system.

Anesthesia and operation may impair the immune system so that bacterial growth and tumor spread may occur more readily, and host response to transplanted tissue and allergenic substances may be altered. Suggestions are presented regarding the anesthetic management of patients at risk from infection or tumor spread.

Trace anesthetic exposure. Consequences and control.

Epidemiologic and animal studies indicate that chronic exposure to anesthetic gases may consitute a potential health hazard. This is suggested by a higher incidence of spontaneous abortion among female operating room personnel, congenital anomalies in the offspring of operating room personnel, and neoplasia of the reticuloendothelial system. Human data show that performance can be compromised during exposure to anesthetic traces. A direct cause and effect relationship between anesthetic exposure and the alleged hazards will require further prospective studies. Such a study is being planned by the Ad Hoc Committee of the American Society of Anesthesiologists. In the interim, monitoring programs should be established to define adequate clearances of the anesthetic agents. Minimum standards and recommended procedures should be established regarding operating room ventilation and design. The use of effective scavengers and anesthetic techniques not requiring the use of inhalational agents should be encouraged. In this way a clear distinction may be defined by the prosepective study planned by the American Society of Anesthesiologists in 1978.

Sodium bicarbonate and systemic hemodynamics in volunteers anesthetized with halothane.

The cardiovascular effects of acute metabolic alkalosis (NaHCO3) in normal male volunteers anesthetized with halothane were measured. Pure metabolic alkalosis was studied by maintaning the end-tidal carbon dioxide tension at 40 torr. In each subject, cardiac index increased and total peripheral resistance decreased after each dose of NaHCO3. The increased cardiac index was associated with increased central blood volume, left ventricular minute work index, stroke index, and heart rate. Systolic time intervals showed increased myocardial performance. NaHCO3 administered to volunteers whose hearts were depressed by halothane appeared to cause peripheral vasodilation, volume expansion, and myocardial stimulation. The authors conclude that NaHCO3 administered during halothane anesthesia decreases total peripheral resistance and may lead to severe hypotension.

Cardiovascular responses to calcium administered intravenously to man during halothane anesthesia.

Calcium chloride (7 mg/kg) was administered intravenously to six healthy volunteers anesthetized with halothane. Cardiovascular changes were measured during constant ventilation and anesthetic depth under three conditions: 1) respiratory alkalosis, 2) normocarbia, and 3) respiratory acidosis. At each Paco2, calcium infusion significantly increased cardiac index, left ventricular minute work index, and stroke index. Heart rate, total peripheral resistance, and cardiac pre-ejection period decreased. No significant change in mean arterial blood pressure or central venous pressure followed calcium administration, and no arrhythmias occurred. It is concluded that calcium administration increases myocardial performance, presumably by increasing the availability of intracellular calcium ion for actomyosin interaction.