John H. Lecky

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) normocarbis, 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 intracelllular calcium ion for actomyosin interaction.

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 < .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 < .05). Recovery room time was from 25 to 52 min longer for DSU patients (P < .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.

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.

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.

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.

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.

The effect of halothane on mitochondrial permeability to NADH

Abstract The effect of halothane on oxidation of exogenous NADH was evaluated in intact and disrupted rat liver mitochondria. A change in oxygen uptake was observed which represented an interplay between inhibition of NADH dehydrogenase (tending to decrease respiratory rate) and loss of impermeability to NADH (tending to increase respiratory rate).

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.

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 arc 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 cither 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.