Edward A. Loeser

Cardiovascular responses to nitrous oxide during light, moderate, and deep halothane anesthesia in man

The cardiovascular effects of addition of 20, 40, and then BO percent N2O or nitrogen during controlled ventilation with light (0.8 percent), moderate (1.2 percent), and deep (1.6 percent) halothane-O2 anesthesia were determined in 39 volunteers and compared to results obtained in 18 additional volunteers who received similar concentrations of halothane-O2 anesthesia alone over the same time interval.Halothane resulted in significant and similar reductions in heart rate at all concentrations studied hut produced concentration-related decreases in mean arterial blood pressure, stroke volume, and cardiac output and increases in right atrial pressure. Halothane did not significantly change peripheral resistance at any concentration. Addition of N2O did not change arterial blood pressure or heart rate at any concentration of halothane but produced increases in right atrial pressure in all groups. Peripheral resistance was reduced and stroke volume and cardiac output increased when N2O was added to 0.8 percent halothane. Subjects anesthetized with 1.2 percent halothane showed no significant change in stroke volume or cardiac output with addition of any concentration of N2O, while those anesthetized with 1.6 per cent halothane sustained reductions in stroke volume and cardiac output with 60 percent N2O. Peripheral resistance remained unaltered during addition of N2O to 1.2 percent halothane but significantly increased with 1.6 percent halothane. Addition of nitrogen to halothane produced changes that were similar to those occurring during continued halothane-O2 administration. These data demonstrate that addition of N2O during halothane-O2 anesthesia produces significant changes in cardiovascular dynamics which are variable and dependent upon the concentrations of halothane and N2O employed. Our findings suggest that N2O blocks the reduction of peripheral vascular resistance and increases in cardiac output, stroke volume, and heart rate seen with continued halothane-O2 administration when added to moderate or deep levels of halothane.

Comparison of droperidol, haloperidol and prochlorperazine as postoperative anti-emetics.

SummaryThe results of this study demonstrate that prochlorperazine, haloperidol and droperidol are all effective post-operative anti-emetic compounds when compared to saline but vary in onset of activity and duration of action. Haloperidol has the shortest onset of action, being effective within 30-minutes of intravenous administration. Prochlorperazine has an intermediate onset of action and droperidol is the slowest of the three compounds but the only one to provide significant anti-emesis 4–24 hours following administration. Our data suggest that a combination of haloperidol and droperidol may be more effective as an anti-emetic than any one of the compounds used alone.RésuméCette étude a pour objet ľévaluation comparative des propriétés anti-émétiques du dropéridol, de ľhalopéridol, de la prochlorpérazine et du soluté physiologique administrés par la voie intramusculaire à 65 opérés ayant vomi en salle de réveil. Ľévaluation a été effectuée à ľaide ďun système de points assignés sur une période déterminée. Ľhalopéridol s’est avéré très puissant et à début ďaction très rapide, son efficacité apparaissant en deçà de trente minutes et déclinant dans les quatre heures suivantes. Ľactivité du dropéridol s’est manifestée beaucoup plus lentement mais son effet maximal est survenu quatre heures après ľadministration. C’est le seul anti-émétique dont ľaction s’est prolongée. Quant à la prochlorpérazine, son activité se situe entre ľhalopéridol et le dropéridol. Ces données portent à croire que ľassociation halopéridol pourrait être plus efficace comme anti-émétique qu’aucun des médicaments étudiés utilisé seul.

Tracheal pathology following short-term intubation with low- and high-pressure endotracheal tube cuffs.

Histologic sections of dog tracheas were taken from 20 dogs anesthetized and intubated for 5 to 7 hours with high-pressure, low-volume Shiley or low-pressure, high-volume Lanz endo-tracheal tubes. Microscopic examination and measurement showed that while the high-pressure, low-volume cuff produced deeper average mucosal erosion, the large-volume, low-pressure cuff resulted in significantly greater lengths of tracheal mucosa-cuff erosion. Maximal depth of penetration throught the basement membrane was similar in both groups. Grooves in the mucosa were seen in 50% of the high-volume-cuff trachea sections but none of the low-volume-cuff tracheal sections. These findings demonstrate that low-pressure, high-volume endotracheal tube cuffs produce different but significant tracheal damage after short-term intubation when compared to high-pressure, low-volume cuffs.

Neutrophil Chemotaxis During Halothane and Halothane-N2O Anesthesia in Man

Polymorphonuclear neutrophil (PMN) function was evaluated in 21 adult male volunteers anesthetized with 0.8, 1.2, or 1.6% halothane-O2, and halothane-O2 plus 20% N2O and 60% N2O. Variables measured included PMN chemotactic index (CI), PMN random migration (RM), and total leukocyte (WBC) and PMN counts. Halothane significantly (p<0.025) increased WBC and PMN counts and caused a concentration-dependent decrease in PMN CI and RM. Addition of 20% N2O did not change any variable; however, adding 60% N2O increased (p<0.05), PMN CI during 1.2 and 1.6% halothane and RM during 1.6% halothane. Termination of N2O reduced CI back to halothane-O2 levels in those receiving 1.2 and 1.6% of the anesthetic but did not significantly alter any other variable. PMN CI and RM remained decreased and WBC and PMN remained elevated during the first 2 postanesthetic hours. WBC and PMN counts were still significantly (p<0.01) elevated the day after anesthesia in the group receiving 1.6% halothane. All other variables returned to control levels 24 hours after anesthesia. These data demonstrate that halothane produces a concentration-dependent reduction in PMN CI which can be partially reversed with the addition of N2O, and suggest that halothane anesthesia may increase susceptibility to bacterial infection by reducing PMN migration toward invading organisms.

THE EFFECTS OF LARGE DOSES OF FENTANYL AND FENTANYL WITH NITROUS OXIDE ON RENAL FUNCTION IN THE DOG

SummaryRenal effects of large doses of fentanyl (1 mg/kg) were determined in 14 mongrel dogs before and after addition of 50 per cent nitrous oxide. Fentanyl significantly increased urine osmolarity and decreased urine output and free water clearance but did not change inulin or PAH clearances. The arterial blood pressure and cardiac output were significantly decreased after 0.1 mg/kg fentanyl and these changes were then maintained during the remainder of the study period. Addition of nitrous oxide produced no further changes in cardiac output and arterial blood pressure but did increase urine output, PAH, inulin and free water clearances and decreased urine osmolarity. These data demonstrate that high doses of fentanyl have significant antidiuretic properties in the dog and these probably are related to the release of antidiuretic hormone. Our results also indicate that addition of nitrous oxide reverses fentanyl induced antidiuresis.RésuméLe but du travail était de définir les effets d’une dose de 1 mg/kg de fentanyl et du fentanyl associé à 50 pour cent de protoxyde d’azote sur la fonction rénale du chien. Aux fins de cette recherche, l’on utilise 14 chiens mâles non prémédiqués.Après la mise en place d’un cathéter de fort calibre, on a procédé à l’induction au moyen de thiopental de Na (2–3 mg/kg ) et de 2 mg/kg de succinylcholine pour faciliter l’intubation. Un cathéter fut mis en place dans la vessie, de même qu’un cathéter dans l’artère fémorale, de façon à mesurer la pression artérielle et le débit cardiaque par la méthode d’analyse par ordinateur de la courbe de pression aortique. Les animaux respiraient 100 pour cent d’oxygène, et leur ventilation était contrôlée par un respirateur volumétrique pour maintenir une pCO2 artérielle entre 30–35 torr.On provoquait la diurèse en infusant 15–20 ml/min de solution 0.45 pour cent NaCl, contenant suffisamment d’inuline et de PAH pour maintenir les concentrations plasmatiques à 25 et 2.5 mg respectivement. La période de contrôle débutait lorsque la diurèse atteignait plus de 5 ml/min. A la fin de chaque période on mesurait le volume urinaire, et on prélevait un échantillon de sang et d’urine pour détermination subséquente de l’inuline et du PAH. Après la période de contrôle, on donnait le fentanyl en dose de 1 mg/kg, par doses fractionnées de 0.1 mg/kg; et des échantillons de sang et d’urine étaient prélevés après 0.1, 0.25, 0.5 et 1.0 mg/kg. A la suite de ces prélèvements, les gaz inspirés étaient changés pour 50 pour cent N2O, 50 pour cent O2 et des échantillons d’urine et de sang étaient prélevés après 15 et 30 min. A la fin de ces sept périodes d’étude, on a mesuré les clearances d’inuline, de PAH, d’eau libre et osmolaire, de même que la pression artérielle et le débit cardiaque.Le fentanyl a provoqué une chute immédiate et significative du débit cardiaque et de la pression artérielle, qui s’est maintenue durant toutes les périodes d’étude. Le fentanyl a aussi provoqué une baisse significative de la diurèse et de la clearance d’eau libre de même qu’une augmentation marquée de l’osmolarité urinaire, mais sans modifier appréciablement l’osmolarité plasmatique ou les clearances de l’inuline, du PAH, ou osmolaire. L’addition de 50 pour cent N2O n’a pas produit de modification significative du débit cardiaque ou de la pression artérielle mais a produit une augmentation significative de la diurèse, des différentes clearances, sauf la clearance osmolaire, ainsi qu’une baisse de l’osmolarité urinaire. L’addition de N2O n’a pas eu effet sur l’osmolarité plasmatique vu la clearance osmolaire.Ces données démontrent que des doses élévées de fentanyl produisent chez le chien une antidiurèse significative tout en n’affectant pas les clearances de l’inuline ou du PAH; ces éléments sont en faveur d’une stimulation de la relâche de l’ADH. Nos résultats indiquent aussi que l’addition de N2O abolit l’antidiurèse induite par le fentanyl.

Cardiovascular effects of scopolamine during morphine-oxygen and morphine-nitrous oxide-oxygen anesthesia in man.

Incomplete amnesia and awareness sometimes complicate morphine (0.5–3.0 mg/kg) or morphine (0.5–1.0 mg/kg)-nitrous oxide anesthesia.1 Scopolamine is often employed as a supplement during both of these techniques to prevent awareness. The cardiovascular effects of this drug during morphine anesthesia have not been investigated, however. In this study we measured the effects of intravenous administration of 0.5 mg scopolamine on cardiovascular dynamics during morphine-oxygen and morphine-nitrous oxide-oxygen anesthesia in 19 patients undergoing open-heart or major vascular operations.

The cardiovascular effects of diazepam and of diazepam and pancuronium during fentanyl and oxygen anaesthesia.

SummaryThe cardiovascular effects of diazepam 0.5 and 1.0 mg/kg and diazepam with pancuronium 0.1 mg/kg after fentanyl 0.5 mg/kg were determined in thirteen dogs premedicated with atropine. Fentanyl produced significant reductions in heart rate, cardiac output and arterial blood pressure. Administration of 0.5 mg/kg of diazepam after fentanyl did not significantly alter stroke volume, arterial blood pressure or peripheral vascular resistance but did increase heart rate and cardiac output. Additional diazepam did not further change the heart rate, but did reduce stroke volume, cardiac output, arterial blood pressure and peripheral vascular resistance. Administration of pancuronium after fentanyl and diazepam produced marked elevations in heart rate, cardiac output and arterial blood pressure. There was no difference in mean heart rate and cardiac output when values prior to fentanyl and those obtained three minutes following pancuronium were compared. These data demonstrate that large doses of fentanyl decrease heart rate, cardiac output and arterial blood pressure in dogs premedicated with atropine but that these changes can be partially reversed with diazepam 0.5 mg/kg and completely antagonized with pancuronium 0.1 mg/kg.RésuméDes travaux antérieurs ont montré que le Fentanyl n’a pas d’effet dépresseur sur la contractilité du myocarde du chien é petites comme à fortes doses. ( 0, 0,2 mg/kg-2 mg/kg).Employé seul pour l’anesthésie clinique, il assure la stabilité cardiovasculaire mais sa puissance amnésique est nettement inférieure à celle de la Morphine. Comme l’addition au Fentanyl a hautes doses de protoxyde d’azote et de Droper-idol deprime de façon sensible la contractilité du myocarde (1, 5 ), on a voulu savoir si le Diazepam et le Pancuronium pouvaient s’employer comme adjuvants sans entraîner cette dépression myocardique.On a done administré du Fentanyl é des chiens selon trois différents régimes: é1. Fentanyl seul, 2. Fentanyl avec Valium, 3. Fentanyl avec Valium-Pancuronium. Les effets cardiovasculaires de ces combinaisons ont été étudiés en mesurant le volume d’éjection, le débit et la fréquence cardiaques, la résistance peériphérique et les pressions artérielles, systolique, diastolique et moyenne.MéthodeLe Fentanyl étant administré à raison de 0,3 mg/min par voie intraveineuse, les mesures furent effectuées à divers stades de l’opération:1.Après chaque dose cumulative de 0,1 mg/kg et ce jusqu’à un total de 0,5 mg/kg.2.Après Fentanyl 0,5 mg/kg et Diazepam 1 mg/kg.3.Après Fentanyl 0,5 mg/kg et Diazepam 1 mg/kg.4.Après addition de 0,1 mg/kg de Pancuronium, les mesures étant effectuées à 1, 3, 5, 7 et 10 minutes après l’injection.RésultatsVoir les tableaux 1 et 2. Le Fentanyl seul è 0,1 mg/kg a occasionné une diminution significative de la fréquence et du débit cardiaque et des pressions artérielles, systolique, diastolique et moyenne, sans modification de la résistance peripherique ou du volume d’éjection. L’écart maximal observable de ces differents paramètres était déjà atteint à cette dose.L’addition de Diazepam à la dose de 0,5 mg/kg a augmente de facon significative la frequence et le debit cardiaques sans modification du volume d’ejection, de la pression arterielle ou de la resistance peripherique ; cependant, è la dose de 1 mg/kg, le Diazepam diminue le volume d’éjection, la résistance péripherique et toutes les pressions artérielles ; de plus, le débit cardiaque revient au niveau observe avant l’injection de Diazepam.Trois minutes apres l’injection du Pancuronium, on voit apparaitre une tachycardie significative, une augmentation du debit cardiaque, de la resistance peripherique et des pressions artérielles. Ces phénomènes, une fois installes, ont persisté tout au long de l’expérience.Ces constatations, chez le chien, démontrent:1.Que le Fentanyl à fortesdoses, malgré une prémédication à l’Atropine, entraine chez le chien une bradycardie, une réduction du débit cardiaque et une diminution de la pression artérielle,2.Que ces effets cardiovasculaires peuvent être partiellement renverses par l’administrationde Diazepam a dose de 0,5 mg/kg et3.Que ces effets cardiovasculaires peuvent etre complètement corrigés par du Pancuronium à dose de 0,1 mg/kg.

Nitrous Oxide Encephalography 5-Year Experience with 475 Pediatric Patients

475 pediatric patients with a variety of neurologic conditions were subjected to encephalography, using N2O as the contrast medium and N2O-halothane as anesthetic agents. This technic is both safe and effective, as reflected by no mortality and satisfactory roentgenograms. By application of the principles of gas physics, postoperative discomfort has been greatly reduced, resulting in a more comfortable convalescence and earlier discharge.

Plastic syringes for epidural anesthesia.

To the Editor: The use of temperature-compensated, flow-independent, precalibrated vaporizers for the delivery of volatile anesthetics adds convenience at the expense of increased mechanical complexity. One assumes that these devices do not deliver anesthetic when they are turned off, but this is not always the case.’ Recently, while refilling a Cyprane Enfluratec variable bypass vaporizer during an operative procedure, the presence of an unsuspected flow of diluent gas was detected. When the fill spout was removed after filling the vaporizer to an appropriate level, the anesthetic poured out, suggesting the presence of flow through the vaporizer. The dial of the vaporizer was apparently turned to ”OFF.” Closer inspection showed that the dial was rotated several degrees past the OFF mark. The dial was reset to the center of the detent position, and the vaporizer was refilled without further incident. The anesthesia machine was removed from service at the completion of the case. It was then discovered that the locking plastic ring was used to ensure positive on-off operation of the vaporizer had worn in such a manner that it was possible to turn the dial several degrees past the OFF position. Before removing the Enfluratec for servicing, gas was collected in sampling bags to measure the concentration of anesthetic being delivered when the dial was rotated past OFF. Using gas chromatography, we found the anesthetic concentration to vary with machine settings of nitrous oxide and oxygen as shown in the Table. The concentrations presented are certainly within the range to produce a clinical effect in some individuals. TABLE