Terry S. Vitez

Where are the costs in perioperative care : analysis of hospital costs and charges for inpatient surgical care

BackgroundMany health-care institutions are emphasizing cost reduction programs as a primary tool for managing profitability. The goal of this study was to elucidate the proportion of anesthesia costs relative to perioperative costs as determined by charges and actual costs.

Effects of hypothermia on halothane MAC and isoflurane MAC in the rat

MAC was determined in tracheotomized rats for halothane (5 rats) and inoflurane (3 rats) at 37, 32, and 27 C. Rectilinear decreases in MAC occurred with both agents. The change with halothane (4.82 per cent per degree) did not differ significantly from that seen with isoflurane (5.28 per cent per de

Chronic Hypokalemia and Intraoperative Dysrhythmias

To investigate whether chronic hypokalemia increases the occurrence of dysrhythmias during anesthesia, the authors recorded the intraoperative electrocardiograms of normokalemic (K+ = 5.0 - 3.5 mEq/1; N = 88) and chronically hypokalemic patients (K+ = 3.4 - 2.6 mEq/1; N = 62). In each patient, serum potassium was measured and a 12-lead ECG was analyzed prior to surgery. No patient received potassium perioperatively. Lead II was monitored continuously during anesthesia, either by a Holter monitor (N = 81) or by a trained observer (N = 69). A variety of general anesthetic techniques were utilized, without consideration for the potassium level. The hypokalemic population had a higher incidence of hypertensive and ASA Class III patients (P = 0.03). Analysis of variance revealed no significant difference in the incidence of other characteristics between the hypokalemic and normokalemic groups: age, hypoxemia, cardiac disease, preoperative dysrhythmias, digitalis therapy, surgical site, anesthetic agent, and intubation. The method of ECG monitoring did not affect the incidence of dysrhythmias recorded. Multivariate analysis revealed that the occurrence of intraoperative dysrhythmias correlated with the presence of preoperative dysrhythmias only. The authors conclude that chronic hypokalemia per se is not associated with a higher incidence of intraoperative dysrhythmias.

Comparative Times to Peak Effect and Durations of Action of Neostigmine and Pyridostigmine

In 30 patients anesthetized with halothane and 60 per cent nitrous oxide, and in 12 cats anesthetized with chloralose and urethane, d-tobo-curarine (dTc) was continuously infused to produce constant 90 per cent depression of twitch height prior to injection of neostigmine or pyridostigmine. Mean times from neostigmine, 0.6, 1.2, or 1.8 mg/m2, or pyridostigmine, 3, 6, or 9 mg/m2 administration to peak antagonism (onset time) of dTc were 11.1, 8.5, and 7.1 minutes with neo-stigmine and 15.8, 16.9, and 12.2 minutes with pyridostigmine in man. Mean times from administration of the same doses of neostigmine and pyridostigmine to 50 per cent return to the dTc-depressed twitch (duration of action) were 37.8, 41.0, and 57.2 minutes with neostigmine and 51.4, 78.8, and 83.6 minutes with pyridostigmine in man. The onset and duration of action times also were longer with pyridostigmine than with neostigmine in the cat. The doses of pyridostigmine and neostigmine needed for 50 per cent antagonism of the dTc-induced depression of twitch height were 4.0 mg/m2 and 0.92 mg/m2 for man and 120 μg/kg and 13 μg/kg for the cat, respectively. Thus, the potency ratio of pyridostigmine to neostigmine is 4.35 (4.0/0.92) in man and 9.3 (120/13) in the cat. We conclude that pyridostigmine has a slower onset and longer duration of action than neostigmine.

Comparison in Vitro of Isoflurane and Halothane Potentiation of d-Tubocurarine and Succinylcholine Neuromuscular Blockades

Neuromuscular blockades with d-tubocurarine (dTe) and succinylcholine (SCh) are enhanced more by isoflurane than by halothane in vivo. We tested the hypothesis that the greater potentiation by isoflurane was the result of a direct action on the neuromuscular junction. Effects of isoflurane and halothane on dTc and SCh blockades were examined in vitro in 52 rat phrenic nerve-diaphragm preparations. At 1, 2, and 4 MAC, the dTc ED50 (dose of relaxant which depresses twitch height by 50 per cent) was decreased 20, 48, and 83 per cent by isoflurane; 29, 49, and 68 per cent by halothane. At 2, 3, and 4 MAC, SCh ED50 was decreased 5, 30, and 50 per cent by isoflurane; 0, 28, and 52 per cent by halothane. We conclude that in vitro, at equal MAC multiples, there is no difference between isoflurane and halothane potentiation of dTc or SCh blockades. We suggest that the greater potentiation of dTc and SCh by isoflurane in vivo does not result from a quantitatively greater effect of isoflurane on the neuromuscular junction.

Effects of Delta–9–tetrahydrocannabinol on Cyclopropane MAC in the Rat

The effects of acute and chronic administration of delta–9–tetrahydrocannabinol (THC) on minimum alveolar anesthetic concentration (MAC) for cyclopropane in rats were determined. MAC was reduced 15.4 (SE ± 3.56) and 25.1 (SE ± 1.43) per cent two hours after intraperitoneal injection of 1.0 and 2.0 mg/kg THC (P < 0.01). Administration of 0.25 or 0.50 mg/kg THC did not change the MAC of cyclopropane. Injections of 0.5, 0.75, or 1.0 mg/kg THC every other day for a week produced no consistent change in MAC measured before each injection. Similarly, the immediate decrease in MAC caused by THC was not altered by chronic administration. Thus, THC can cause a significant reduction in MAC, and this effect is unaltered by chronic administration of low doses.

Where Are the Costs in Perioperative Care? Analysis of Hospital Costs and Charges for Inpatient Surgical Care

Background Many health‐care institutions are emphasizing cost reduction programs as a primary tool for managing profitability. The goal of this study was to elucidate the proportion of anesthesia costs relative to perioperative costs as determined by charges and actual costs.

Induction Using Fentanyl to Suppress the Intubation Response in the Cardiac Patient: What is the Optimal Dose?

Eighty patients undergoing coronary artery surgery were randomly allocated to receive either 0, 2, 5, 10 or 15 micrograms/kg of fentanyl with induction of anaesthesia. Heart rate and blood pressure were measured before induction, after induction, and after intubation. The effects of fentanyl dose on both heart rate and mean arterial pressure (MAP) were evaluated in terms of both the mean and group responses. At all doses of fentanyl, mean heart rate increased after induction and rose further on intubation. The mean increase after induction was minimal at doses of 5 micrograms/kg and greater. The increase in heart rate after intubation was more difficult to block but with a fentanyl dose of 15 micrograms/kg, 87% of patients had heart rates below 100 bpm. As a group, the percentage of patients in whom the postintubation heart rate remained below 100 bpm increased progressively with the fentanyl dose. In contrast, mean MAP fell at all dose levels after induction, the mean fall being about 30 mmHg at 5 micrograms/kg and greater. Mean MAP exceeded pre-induction values after intubation with 0 and 2 micrograms/kg, and progressive attenuation of the MAP rise was found as the dose of fentanyl increased. The percentage of patients who did not exceed their preinduction MAP rose progressively with increasing dose of fentanyl with an ED50 of 3.7 micrograms/kg. If a minimal fall in mean MAP after induction with no rise above preinduction MAP is the sole criterion, a fentanyl dose of about 3 micrograms/kg is recommended. If heart rate is to be kept below 100 bpm, a dose of at least 10 micrograms/kg should be used.2+ dose or greater will cause the MAP to fall in some patients to less

Sympathoadrenal Responses to Cold and Ketamine Anesthesia in the Rhesus Monkey

The effect of cold exposure on the sympathoadrenal system in primates was studied with and without ketamine anesthesia in eight adult rhesus monkeys. Each monkey was placed in a primate chair at a thermoneutral temperature (25 degrees C) for 1 h (control) followed by cold exposure (12 degrees C) for 3 h or placed in a circulating water bath (28 degrees C) to induce a decrease in core temperature (Tre) to 35 and 33 degrees C. Plasma catecholamines were analyzed by high-pressure liquid chromatography with electrochemical detection (60-65% recovery, coefficient of variation = 15%). The 3-h cold exposure was associated with a 175% increase above control levels of norepinephrine (NE) and a 100% increase in epinephrine (E). Decreases were evident in Tre (0.5 degree C), mean skin temperature (Tsk, 5.5 degrees C), and mean body temperature (Tb, 2.0 degrees C). Continuous infusion of ketamine (0.65 mg . kg-1 . min-1) resulted in no change in the plasma levels of NE and E from the control levels. Tre, Tsk, and Tb all showed greater declines with the addition of ketamine infusion to the cold exposure. Water exposure (28 degrees C) under ketamine anesthesia resulted in a drop in Tre to 33 degrees C within 1 h. Plasma levels of NE and E were unchanged from control values at Tre of 35 and 33 degrees C. The data suggest that the administration of ketamine abolished both the thermoregulatory response and the catecholamine response to acute cold exposure.

Continuous Propranolol Infusion Following Abdominal Surgery

Thirteen patients given long-term propranolol hydrochloride therapy for heart disease required 15 abdominal surgical procedures. On each occasion, propranolol therapy was maintained postoperatively by continuous intravenous infusion. Duration of infusion ranged from one to nine days, and each infusion was monitored with frequent measurements of serum propranolol concentrations. In patients with normal hepatic and renal function, therapeutic serum propranolol levels were attained with a narrow dose range averaging 3.0 mg/hr, irrespective of body weight. All patients had postoperative courses free of complications attributable to beta-blockade. This form of therapy appears to protect against sympathetic stimulation during the perioperative period and to prevent the propranolol withdrawal syndrome in such patients. Continuous propranolol infusion might also be useful in other clinical situations, such as acute aortic dissection or severe thyrotoxicosis, where predictable therapeutic serum propranolol levels could be maintained when oral therapy was contraindicated.