Duke B. Weeks

Venous carbon dioxide embolism during laparoscopy.

A 31-year-old, multiparous, 60-kg woman in the 10th week of pregnancy was brought to the operating room for a therapeutic abortion and tuba1 ligation. She had been given general anesthesia for a dilatation and curettage (D & C) 3 years before without difficulty. Her medical history was without significant abnormalities. Physical examination showed normal findings, including absence of heart murmur. All laboratory findings were normal.

Laboratory investigation of six artificial noses for use during endotracheal anesthesia.

The performances of six commercially available heat and moisture exchangers (HMEs) or “artificial noses,” were evaluated in the laboratory. Each HME was studied with both a semiclosed anesthesia circuit (SCAC) and a nonrebreathing anesthesia system (NRS). Our results suggest that the Servohumidifier 150 and the Engström Edith are suitable for replacing nasopharyngeal humidification mechanisms bypassed during endotracheal ventilation in all patients because they provided at least 20 mg of water per liter of minute ventilation (mg/L) in an NRS and 28 mg/L in an SCAC during inspiration. While the other four units were suitable for small tidal volumes, they only marginally satisfied minimal suggested humidity levels in the presence of larger tidal volumes.

Small-dose propofol by continuous infusion does not prevent postoperative vomiting in females undergoing outpatient laparoscopy

This study was designed to test the hypothesis that there is a direct prophylactic antiemetic effect of small-dose propofol given by continuous infusion. Sixty female patients undergoing outpatient laparoscopy under general anesthesia were randomized to receive, in a double-blind fashion, either a bolus of 0.1 mg/kg followed by a constant infusion of 1 mg [center dot] kg-1 [center dot] h-1 of propofol or an equivalent volume of 10% Intralipid[R] (placebo) beginning 30 min before induction of anesthesia and continuing until discharge from Stage I postanesthesia care unit (PACU). Anesthesia was induced and maintained in a standard fashion in all patients. The number of emetic episodes before and after discharge from PACU, nausea scores (11-point numerical scale), and time to discharge were evaluated. No significant differences between Intralipid[R] and propofol were found for any of the outcome variables tested. While small-dose propofol is an effective adjuvant in reducing chemotherapy-induced emesis, we were unable to demonstrate any beneficial effect of propofol in reducing postoperative nausea and vomiting when used as the sole prophylactic medication in this patient population. Propofol may have a synergistic effect when administered with other antiemetics, or the specific antiemetic effect of propofol, if it exists, may be dose-dependent and the dose used in this study was below the efficacy threshold. (Anesth Analg 1997;84:71-5)

A randomized, double-blind, placebo controlled comparison of droperidol, ondansetron, and metoclopramide for the prevention of vomiting following outpatient strabismus surgery in children

STUDY OBJECTIVE To compare the efficacy of ondansetron, droperidol, or metoclopramide with placebo in preventing postoperative vomiting following strabismus surgery. STUDY DESIGN Randomized, double-blind, placebo-controlled clinical trial. SETTING University outpatient surgery center. PATIENTS 160 ASA physical status I and II children ages 1 to 12 years who were scheduled for strabismus surgery. INTERVENTIONS Administration of either ondansetron 100 mcg/kg, metoclopramide 250 mcg/kg, droperidol 75 mcg/kg, or placebo intravenously after induction of anesthesia. MEASUREMENTS AND MAIN RESULTS Both ondansetron and droperidol were superior to metoclopramide and placebo in preventing predischarge vomiting, with incidences of 5%, 5%, 32%, and 25%, respectively. However, there was no difference in the incidence of postdischarge vomiting among the groups (ondansetron 25%, droperidol 25%, metoclopramide 20%, and placebo 25%). CONCLUSIONS While both ondansetron and droperidol are more effective than metoclopramide when compared with placebo in decreasing the incidence of predischarge vomiting, none of these drugs was more effective than placebo in decreasing the incidence of postdischarge vomiting. Recovery from anesthesia was not significantly different among the groups as assessed by time to awakening, initial Steward score, and time to discharge.

Oxygen administration during transport and recovery after outpatient surgery does not prevent episodic arterial desaturation

STUDY OBJECTIVE To compare the efficacy of two different oxygen (O2) delivery systems in preventing episodic arterial desaturation in the immediate postoperative period. STUDY DESIGN Randomized, prospective, nonblinded comparison in patients. SETTING Operating room and postanesthesia care unit (PACU) of a university outpatient surgery center. PATIENTS 100 ASA status I and II adults, male and female, age greater than 18 years, undergoing outpatient surgical procedures not involving the upper airway. INTERVENTIONS Group I received supplemental O2 administered by bag-valve-mask during transport, followed by 40% face shield in the PACU. Group 2 received supplemental O2 by nasal cannula at 4 L/min both during transport and during PACU stay. MEASUREMENTS AND MAIN RESULTS Arterial O2 saturation (SpO2) was collected by computer from a recording pulse oximeter at 15-second intervals beginning before extubation and continuing until O2 administration was discontinued in PACU. Neither mode of therapy was successful in completely eliminating arterial desaturation defined as SpO2 less than 90%, nor was there any difference in efficacy between the two treatment groups. Group 1 had 8 patients desaturate on 9 different occasions (5 times during transport, 4 times in PACU). Group 2 had 5 patients desaturate on 9 different occasions (4 times during transport, 5 times in PACU). CONCLUSION Routine O2 administration during transport and PACU stay did not abolish episodic desaturation, even in healthy patients undergoing minor surgical procedures. Given the marked difference in acquisition cost, it would appear that O2 administration by nasal cannula is a more cost-effective alternative for routine postoperative O2 administration in certain groups of patients undergoing general anesthesia for outpatient surgery.

Provision of endogenous and exogenous humidity for the Bain breathing circuit.

SummaryThe endogenous humidity produced by a partial rebreathing system, the Bain Breathing Circuit, was measured clinically and experimentally. The addition of humidification by interposing a Garthur Vapor Condenser (HME) or a Bennett Cascade heated humidifier into the system was also studied.Without supplemental humidity, the Bain Breathing Circuit probably meets marginal requirements for preservation of ciliary morphology and function during endotracheal anaesthesia. However, additional humidity is needed to prevent alteration in pulmonary mechanics. The HME is a beneficial adjunct to the Bain Breathing Circuit, raising humidity to near acceptable levels, especially if ambient temperatures range from 24° to 26° C. However, the deadspace of the HME is 17 ml, which might limit its use in children. The Bennett Cascade humidifier plus the Bain Breathing Circuit satisfies minimal suggested humidity requirements at ambient reservoir water temperatures of 24° to 26° C. Heating the reservoir water to maximum heat capacity increased humidity but caused marked water condensation along the inner fresh gas tube of the Bain Breathing Circuit.RésuméNous avons fait la mesure en laboratoire et en clinique de l’humidité endogène produite par la réinspiration partielle dans un circuit de Bain. On a également étudié les effets produits par l’addition au système d’un condensateur de vapeur Garthur ( HME ) ou d’un humidificateur Bennet.L’humidité d’origine endogène lorsque le circuit de Bain est utilisé seul, se situe en moyenne à 13 mg/1 ou 64 pour cent d’humidité relative à température de la pièce, ceci après dix minutes de fonctionnement. L’addition du condensateur HME élève en 15 minutes le taux d’humidité à une moyenne de 19.4 mg/1 ou 92 pour cent d’humidité relative à température de la pièce. L’interposition d’un humidificateur Cascade à température de la pièce, élève le taux moyen à 21 mg/1 ou 100 pour cent d’humidité relative. Si maintenant l’on fait chauffer le Cascade à son maximum, l’on retrouve un taux de 28 mg/1 (100 pour cent d’humidité relative à 28.5° C); et il y a production de condensation dans le circuit de Bain avec effets bronchiques nocifs possibles.Utilisé seul, le circuit Bain répond probablement à la limite aux exigences d’humidité permettant une conservation de la morphologie et de la fonction ciliaire durant l’anesthésie endotrachéale. Il faut cependant fournir davantage pour conserver la mécanique pulmonaire. Lorsque la température de la pièce varie entre 24–26° C, l’interposition d’un condensateur peut élever l’humidité relative à des taux acceptables. Cependant, cet appareil ajoute 17 ml à l’espacement, inconvénient possible chez l’enfant.L’addition d’un vaporisateur Bennett avec eau chauffée entre 24 et 26° répond probablement aux besoins d’humidité suggérés. Si par ailleurs on élève la température de l’eau au maximum, le Bennett fournit probablement une humidification comparable à celle fournie par la muqueuse nasale, mais l’on assiste alors à de la condensation dans le circuit de Bain, ce qui contrebalance les avantages obtenus.

A Method of Quantitating Humidity in the Anesthesia Circuit by Temperature Control: Semiclosed Circle

UMIDIFICATION of anesthetic gases has H been emphasized as a necessary supplement to anesthetic management.1-4 However, the methods of generating humidity and the physical cliaracteristics and quantity of added water content have been debated.l.5--7 The two methods in current use are ultrasonic nebulized aerosols, which have received vigorous investigation, and water vapor produced by heated humidifiers, described as the control or more physiologic approach.ls.5.8