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The purpose of this study was to test the hypothesis that using a 1:4 ratio of remifentanil to alfentanil, a remifentanil infusion would provide better suppression of intraoperative responses and comparable recovery profiles after ambulatory laparoscopic surgery than an alfentanil infusion, as part of total intravenous anesthesia. Two hundred ASA physical status I, II, or III adult patients participated in this multicenter, double-blind, parallel group study. Patients were randomly assigned 2:1 to either the remifentanil-propofol or alfentanil-propofol regimens. The anesthesia sequence was propofol (2 mg/kg intravenously [IV] followed by 150 micrograms.kg-1.min-1), and either remifentanil (1 microgram/kg IV followed by 0.5 microgram.kg-1.min-1)of alfentanil (20 micrograms/kg IV followed by 2 micrograms.kg-1.min-1), and vecuronium. After trocar insertion, infusion rates were decreased (propofol to 75 micrograms.kg-1.min-1; remifentanil to 0.25 microgram.kg-1.min-1; alfentanil to 1 microgram.kg-1.min-1). Alfentanil and propofol were discontinued at 10 and 5 min, respectively, before the anticipated end of surgery (last surgical suture); remifentanil was discontinued at the end of surgery. Recovery times were calculated from the end of surgery. The median duration of surgery was similar between groups (39 min for remifentanil versus 34 min for alfentanil). A smaller proportion of remifentanil patients than alfentanil patients had any intraoperative responses (53% vs 71%, P = 0.029), had responses to trocar insertion (11% vs 32%, P0.001), or required dosage adjustments during maintenance (24% vs 41%, P0.05). Early awakening times were similar. Remifentanil patients qualified for Phase 1 discharge later and were given postoperative analgesics sooner than alfentanil patients (P0.05). Actual discharge times from the ambulatory center were similar between groups (174 min for remifentanil versus 204 min for alfentanil) (P = 0.06). In conclusion, remifentanil can be used for maintenance of anesthesia in a 1:4 ratio compared with alfentanil, for total IV anesthesia in ambulatory surgery. This dose of remifentanil provides more effective suppression of intraoperative responses and does not result in prolonged awakening.

The objective of this study was to determine whether unregulated self-medication in an ambulatory surgery population was a significant problem in terms of the incidence and nature of drugs detected. We asked 67 consecutive patients who presented for elective ambulatory surgery at a university medical center to volunteer for serum and urine testing with the assurance of confidentiality. All patients denied nonprescription drug use. Initial testing was for amphetamines, barbiturates, benzodiazepines, cocaine, opiates, phencyclidine (PCP), tetrahydrocannabinol (THC) and alcohol. Of the 64 patients who agreed to be tested, 16 patients tested positive for at least one of the above substances; 4 patients demonstrated residua of 2 or 3 substances. No distinctive characteristic of those with evidence of drug use could be identified. We believe that the 25% of patients who tested positive in this group is a conservative estimate of possible unrecognized drug use. We have demonstrated a significant incidence of substance abuse in the ambulatory surgery environment. These findings have serious safety implications, and a higher awareness of possible nonprescription drug use in this environment is needed in medical and support personnel.

This study was undertaken to compare desflurane with propofol anesthesia in outpatients undergoing peripheral orthopedic surgery. Data were combined from two institutions participating in a multicenter study. Ninety-one patients, ASA physical status I or II, were each randomly assigned to one of four groups. After administration of fentanyl (2 micrograms/kg) and d-tubocurarine (3 mg), intravenous propofol was administered to induce anesthesia in groups I and II and desflurane in groups III and IV. Maintenance was provided by desflurane/N2O in groups I and III, propofol/N2O in group II, and desflurane/O2 in group IV. Emergence and recovery variables, psychometric test results, and side effects were recorded by observers unaware of the experimental treatment. Patients in group II experienced less nausea than other groups (P = 0.002) despite this group having required more intraoperative fentanyl supplementation than groups III and IV (P = 0.01). Time to emergence, discharge, and psychometric test results were similar in all groups. Desflurane appears to be comparable with propofol as an outpatient anesthetic, facilitating rapid recovery and discharge home.

The effect of protamine sulfate on several cardiovascular and biochemical variables was studied in man under clinical conditions. This study was performed to quantitate these effects in 15 adult patients who had undergone cardiopulmonary bypass for coronary artery bypass grafting. Protamine was administered in typical clinical doses (3 mg/kg) at typical clinical rates (total dose infused over 5 minutes). This infusion rate is greatly in excess of the 50 mg/10 min suggested in the protamine package insert. No statistically significant changes in mean arterial blood pressure, cardiac output, central venous pressure, total or ionized calcium, PaO2, PaCO2, pH, Na+, or K+ were found during or after administration of protamine sulfate. Hypotension was observed after administration of protamine to one patient, but no etiologic mechanism was apparent. Previous reports suggest cardiovascular depression by protamine in the dog, a species highly susceptible to these effects. Data obtained in man in this study do not corroborate the canine studies.

Potassium (K+) is often administered to patients during cardiopulmonary bypass (CPB). The effects of rapid K+ administration during CPB were studied in 30 adult patients. Each patient received one bolus dose (2, 4, 8, 12, or 16 mEq) of potassium chloride (KCl) (2 mEq/ml) during CPB. Serum K+ was significantly increased from baseline values at KCl doses of 8 mEq and larger (p less than 0.05). All increases in serum K+ returned to clinically acceptable levels within 5 minutes after the bolus. Mean arterial pressure (MAP) (torr) and total peripheral resistance (TPR) (dynes sec cm-5) changes were biphasic; after an initial transient decrease, maximal with the 16 mEq K+ bolus (MAP -21 +/- 6, TPR - 315 +/- 135), these parameters increased (8 mEq K+ bolus, MAP + 15 +/- 16, TPR + 301 +/- 90; 12 mEq K+ bolus, MAP + 43 +/- 9, TPR + 998 +/- 250; 16 mEq bolus, MAP + 51 +/- 9, TPR + 1,216 +/- 120) with a peak at 3 minutes after the bolus. Hypertension, in nine of 18 patients receiving a KCl bolus of 8 mEq or larger, was of such magnitude (range 132 to 196 torr) as to require rapid therapeutic intervention to lower blood pressure. When KCl supplementation is required on CPB and slow infusion rates seem unreasonable, bolus doses of less than 8 mEq may be administered without vascular effect.

The hemodynamic effects of high-frequency jet ventilation (HFJV) and conventional ventilation were compared in normovolemic and functionally hypovolemic dogs. In normovolemic animals, no differences in hemodynamic function were found among spontaneous ventilation, conventional ventilation, and HFJV. When venous return was impaired by 15 cm H2O PEEP, cardiac index and stroke index were 25% higher with HFJV than with conventional ventilation (P less than 0.05). In another study with PEEP, conventional ventilation was compared to spontaneous ventilation, HFJV synchronized to five different parts of the cardiac cycle, and asynchronous HFJV. Heart rate was 15% lower and mean arterial pressure was 26% lower with conventional ventilation than with HFJV modes (P less than 0.05). There were no differences between synchronous and asynchronous HFJV. These results indicate that hemodynamic dysfunction may be less likely with HFJV than conventional ventilation. No advantage of synchronizing jet pulsations to a specific part of the cardiac cycle could be demonstrated.

The hemodynamic effects of high-frequency jet ventilation (HFJV) and conventional ventilation were compared in normovolemic and functionally hypovolemic dogs. In normovolemic animals, no differences in hemodynamic function were found among spontaneous ventilation, conventional ventilation, and HFJV. When venous return was impaired by 15 cm H2O PEEP, cardiac index and stroke index were 25% higher with HFJV than with conventional ventilation (P less than 0.05). In another study with PEEP, conventional ventilation was compared to spontaneous ventilation, HFJV synchronized to five different parts of the cardiac cycle, and asynchronous HFJV. Heart rate was 15% lower and mean arterial pressure was 26% lower with conventional ventilation than with HFJV modes (P less than 0.05). There were no differences between synchronous and asynchronous HFJV. These results indicate that hemodynamic dysfunction may be less likely with HFJV than conventional ventilation. No advantage of synchronizing jet pulsations to a specific part of the cardiac cycle could be demonstrated.

Potassium (K+) is often administered to patients during cardiopulmonary bypass (CPB). The effects of rapid K+ administration during CPB were studied in 30 adult patients. Each patient received one bolus dose (2, 4, 8, 12, or 16 mEq) of potassium chloride (KCl) (2 mEq/ml) during CPB. Serum K+ was significantly increased from baseline values at KCl doses of 8 mEq and larger (p less than 0.05). All increases in serum K+ returned to clinically acceptable levels within 5 minutes after the bolus. Mean arterial pressure (MAP) (torr) and total peripheral resistance (TPR) (dynes sec cm-5) changes were biphasic; after an initial transient decrease, maximal with the 16 mEq K+ bolus (MAP -21 +/- 6, TPR - 315 +/- 135), these parameters increased (8 mEq K+ bolus, MAP + 15 +/- 16, TPR + 301 +/- 90; 12 mEq K+ bolus, MAP + 43 +/- 9, TPR + 998 +/- 250; 16 mEq bolus, MAP + 51 +/- 9, TPR + 1,216 +/- 120) with a peak at 3 minutes after the bolus. Hypertension, in nine of 18 patients receiving a KCl bolus of 8 mEq or larger, was of such magnitude (range 132 to 196 torr) as to require rapid therapeutic intervention to lower blood pressure. When KCl supplementation is required on CPB and slow infusion rates seem unreasonable, bolus doses of less than 8 mEq may be administered without vascular effect.