Lawrence S. Berman

Wakefulness during Cesarean Section after Anesthetic Induction with Ketamine, Thiopental, or Ketamine and Thiopental Combined

Thirty-six pregnant women (ASA class I or II) at term who underwent general anesthesia and cesarean section received either ketamine, 1 mg/kg (n = 12); thiopental, 4 mg/kg (n = 13); or a combination of ketamine, 0.5 mg/kg, and thiopental, 2 mg/kg (n = 11). A blood pressure cuff inflated to 250 mm Hg isolated one arm from the effects of succinylcholine so that awareness during anesthesia could be assessed by asking the patient to move her hand. Although only one patient receiving ketamine responded to commands during anesthesia, 46% of patients receiving either thiopental or the combination responded to commands intra-operatively. No patient hallucinated, the incidence of dreams was low (11%), and no postoperative dysphoria was noted. Three patients (8%) had postoperative recall of intraoperative awareness; one had received thiopental and two the combination. Maternal intraoperative cardiovascular responses among the groups were similar, as were umbilical blood gas values, newborn Apgar scores, and neonatal neurobehavioral test scores at 4 and 24 hr. Ketamine more effectively blocked maternal responsiveness to commands and strong stimuli during the first few minutes after anesthetic induction for cesarean section than did thiopental or a combination of thiopental and ketamine, each at a lower dose.

Catecholamine and cortisol responses to sufentanil-O2 and alfentanil-O2 anaesthesia during coronary artery surgery

The effects of alfentanil-O2 and sufentanil-O2 anaesthesia on plasma catecholamines and cortisol were investigated in 32 patients undergoing coronary artery bypass grafting operations. After lorazepam-atropine premedication and pancuronium pretreatment, alfentanil was given to 16 patients at a rate of 3 mg-* min-1 and sufentanil was given to 16 patients at 300 εg*min-1 until the patients were unconscious; at this time they were given succinylcholine and were inlubated. After intubation an amount of alfentanil or sufentanil equal to the dose producing unconsciousness was infused over the next 30 min, at which time the operation began. Additional alfentanil or sufentanil were given whenever systolic arterial blood pressure increased more than 15 per cent of preanaesthetic values. Arterial blood samples were obtained for epinephrine, norepinephrine and cortisol assay and cardiovascular dynamics were recorded prior to anaesthetic induction, 5 min after tracheal intubation, immediately prior to and five min after incision, ten min after maximal sternal spread, just prior to beginning and after 30 and 60 min of bypass and at the end of operation. Cardiovascular dynamics were little changed throughout anaesthesia and operation. Plasma epinephrine and norepinephrine were not significantly changed until bypass. During bypass both hormones became increased and remained increased at the end of operation. Plasma cortisol decreased after incision and remained decreased until the end of operation. These data indicate that alfentanil-O2 and sufentanil-O2 anaesthesia produce similar changes in plasma catecholamines and cortisol as does fentanyl O2 anaesthesia and hormonal effects are, therefore, not an explanation for any advantages the newer narcotics may have over fentanyl.RésuméLes effets de l’anesthésie avec de l’alfentanil-O2 et du sulfentanil-O2 sur Ie plasma catécholamine et cortisol ont été étudiés chez 32 patients subissant un pontage aorto-coronarien. Après une prémédication de lorazepan-atropine et un traitement au pancuronium, de l’ alfentanil fut administré d seize patients en dose de 3 mg * min-1 et du sulfentanil en dose de 300 εg * min-1 fut administré aux seize autres patients jusqu’à ce qu’ils s’endorment. Ensuite on lew donna de la succinylcholine et on procéda à I’intubation trachéale. Après l’intubation, une dose d’alfentanil ou de sulfentanil égale à la dose utilisée pour les endormir jut injectée pendant les 30 minutes suivantes et on commença l’ intervention chirurgicale. Lorsque la tension artérielle augmentait à plus de 15 pour cent des taux préanesthésiques, on ajoutait un supplément d’alfentanil ou de sulfentanil. Des prélèvements de sang artériel furent obtenus pour l’analyse de I’épinéphrine, de la norépinéphrine et du cortisol et la dynamique cardio-vasculaire fut notée avant l’induction de l’anesthésie, cinq minutes après l’intubation trachéale, immédiatement avant et cinq minutes après l’incision, dix minutes après Vextension sternale maximum, juste avant le début et après 30 minutes et 60 minutes du pontage cardio-pulmonaire et à la fin de l’opération. La dynamique cardio-vasculaire changea peu pendant la durée de l’anesthésie et de l’opération. Le plasma épinéphrine et norépinéphrine ne changèrent pas significativement jusqu’ au moment du pontage. Pendant le pontage les deux hormones s’accentuèrent et continuèrent ainsi jusqu’ à la fin de l’opération. Le plasma cortisol diminua après l’incision et continua ainsi jusqu’ à la fin de l’opération. Ces données indiquent que l’ alfentanil-O2 et le sulfentanil-O2 pour l’anesthésie engendrent des changements dans le plasma catécholamine et cortisol comme I’anesthésie avec le fentanyl-O2 et ne procure aucune explication sur les avantages que les nouveaux narcotiques peuvent avoir sur le fentanyl.

Capnographic detection of anaesthesia circle valve malfunctions

To determine whether capnographic waveforms can characterize valve malfunction of the anaesthesia circle, which would enable such problems to be identified and rectified immediately, we monitored capnographic respiratory waveforms during anaesthesia with simulated circle valve malfunctions. Ten mongrel dogs were anaesthetized with pentobarbitone, 25 mg·kg-1 IV, and halothane, 0.5 to 1 per cent. Respiratory gas was sampled from the elbow of the circle system for capnographic monitoring, At fresh gas flow rates of 2.5 or 5 L·min-1 during consecutive periods of controlled and spontaneous ventilation, the inspiratory valve, the expiratory valve, or both valves of the circle system were opened for 15 min. Inspired CO2 concentration increased significantly every time a valve was opened, except during spontaneous breathing at 5 L·min-1. At 2.5 L·min-1, inspired CO2 increased from baseline to 0.41 ± 0.28 per cent with the inspiratory valve opened and to 2.22 ° 1.72 per cent with the expiratory valve opened during controlled ventilation and to 0.43 ± 0.20 per cent and 2.02 ± 1.28 per cent, respectively, during spontaneous ventilation. Inspired CO2 increased to almost I per cent when the inspiratory valve was open and to ≥ 1.89 per cent when the expiratory valve was open. The effects with the expiratory valve open and with both valves open were similar. Capnograms were affected in characteristic ways by the valve malfunctions.RésuméAfin de déterminer si ľonde obtenue par capnographie peut détecter un malfonctionnement des valves du circuit anesthêsique permettant une correction immédiate, on a étudié ces tracés durant ľanesthésie en simulant un malfonctionnement de ces valves. Dix chiens bâtards ont été anesthésiés avec du pentobarbital, 25 mg· kg-1 IV et de ľhalothane 0.5 à I pour cent. Les gaz ont été échantillonnés du coude du circuit pour étude capnographique. Des flots de gaz frais de2.5 à 5.0 L · min-1 durant des périodes consécutives de ventilation contrôlée et spontanée, la valve inspiratoire, la valve expiratoire ou les deux valves du circuit ont été ouverts pour 15 minutes. Les concentrations de CO2 inspirées augmentèrent significativement à chaque fois que la valve était ouverte, excepté lors de la respiration spontanée à 5 L·min-1. A2.5 L·min-1 te CO2 inspiré augmenta de la ligne de base à 0.41 ± 0.28 pour cent quand la valve inspiratoire était ouverte et à 2.22 ± 1.72 pour cent quand la valve expiratoire était ouverte lors de la ventilation contrôlée et à 0.43 ± 0.20 pour cent et 2.02 ± 1.28 pour cent respectivement, durant la ventilation spontanée. Le CO2 inspiré augmenta jusqu’ à environ 1 pour cent quand la valve inspiratoire était ouverte et à± 1.89 pour cent quand la valve expiratoire était ouverte. Des résultats similaires furent obtenus avec la valve expiratoire ouverte et avec les deux valves ouvertes. La capnographie était caractéristique lors des malfonctionnements de valve.

Artificial surfactant for therapy in hydrocarbon-induced lung injury in sheep

OBJECTIVEnTo document the effect of administering artificial surfactant into the trachea, either by instillation or aerosolization, on acute lung injury experimentally induced with kerosene in sheep.nnnDESIGNnRandomized, prospective, controlled study.nnnSETTINGnResearch laboratory.nnnSUBJECTSnSheep (n = 24), weighing 8.5 to 25.2 kg (average 16.6).nnnINTERVENTIONSnIn anesthetized, tracheally intubated sheep with pulmonary and femoral artery catheters inserted, lung injury was induced by instilling kerosene (0.3 mL/kg) into the trachea. After 15 mins of spontaneous breathing, mechanical ventilation was instituted with a uniform F10(2) and a tidal volume of 10 mL/kg. Sheep were then assigned randomly to one of four regimens as follows: exogenous surfactant or saline (5 mL/kg each) was administered as a bolus intratracheally or by aerosolization for 6 hrs.nnnMEASUREMENTS AND MAIN RESULTSnArterial and mixed venous blood gases, pH, airway pressure, and static respiratory system compliance were measured and compared between aerosol saline and aerosol surfactant and between bolus saline and bolus surfactant. For all variables except static respiratory system compliance, the hourly rate of change from 15 mins, 1 hr, and 6 hrs after kerosene instillation was determined for each animal, and group rank sums of hourly rates of change were compared. For static respiratory system compliance, the slope of the pressure-volume curve with volumes of 100, 200, 300, 400, and 500 mL was computed for each animal at baseline and at 3 and 6 hrs after kerosene instillation. Group rank sums for static respiratory system compliance at 3 and 6 hrs were compared. Also, the 3- and 6-hr static respiratory system compliance values at each of the volumes were compared. With saline, six of eight sheep died; with surfactant, no sheep died (p = .001). When compared with saline at 15 mins, 1 hr, and 6 hrs after kerosene instillation, surfactant, regardless of whether administered by aerosol or bolus, significantly increased rate of change of arterial oxygen saturation, mixed venous oxygen saturation, and PO2.nnnCONCLUSIONSnIn the present animal study, artificial surfactant was an effective treatment for hydrocarbon aspiration. Aerosolized surfactant achieved results similar to instilled surfactant but at a lower total dose.

Comparison of awake endotracheal intubation in patients with cervical spine disease: the lighted intubating stylet versus the fiberoptic bronchoscope.

A wake endotracheal intubation followed by brief neurological examination before the induction of general anesthesia is an accepted practice for patients with cervical spine disease with symptoms of myelopathy and for patients at risk of spinal cord compression during standard endotracheal intubation (1). Awake intubation is performed with the fiberoptic bronchoscope (FOB) either by the nasal or oral route, the nasal route being relatively more common. The success rate of FOB intubation ranges from 72% to 98% (2-5). The lighted intubating stylet (LIS) has been used for indirect endotracheal intubation with success rates between 88% and 100% (6-9). Studies have demonstrated the efficiency of the LIS for managing the difficult airway in children (10) and in patients with maxillofacial injury (11). Use of the LIS is part of the ASA’s difficult airway algorithm (12). Because the LIS allows endotracheal intubation with minimal movement of the cervical spine, it is ideally suited for patients with myelopathy. Fox et al. (13) compared the LIS with blind nasotracheal intubation in awake patients with cervical spine disease and found the LIS to be superior, with greater speed, fewer required attempts, and reduced incidence of complications. Because awake nasotracheal intubation with the FOB is a common method of endotracheal intubation in patients with myelopathy, it is important to compare this technique with orotracheal intubation using the LIS.

A new pediatric respiratory monitor that accurately measures imposed work of breathing: a validation study.

Objective. A new, microprocessor-controlled respiratory monitor (model CP-100 Pediatric, Bicore Monitoring Systems, Irvine, CA) that measures imposed work of breathing and a variety of respiratory parameters for pediatric patients receiving ventilatory support has recently been developed. To validate its accuracy, measurements obtained using this monitor were compared with those obtained using conventional laboratory equipment.Methods. An in vitro lung model was used to simulate spontaneously breathing pediatric patients ranging from infancy to 10 years of age. Tidal volume, respiratory rate, and peak inspiratory flow rates were simulated in a stepwise manner. Values for imposed work, tidal volume, peak inspiratory flow rate, and change in airway pressure for both methods were compared using regression analysis.Results. The coefficients of determination (r2) describing the relationships of both methods of measuring imposed work, tidal volume, peak inspiratory flow rate, and the change in airway pressure ranged from 0.99 to 1.00, and were highly significant (p<0.001). For all measurements, bias was minimal and precision was calculated.Conclusions. Our data reveal that this pediatric respiratory monitor accurately measures imposed work of breathing, as well as tidal volume, flow rate, and airway pressure. Imposed work of breathing measurements obtained from the monitor may be used to adjust pressure support ventilation, so that the imposed work of the breathing apparatus is reduced to zero and the patients total work of breathing is thus decreased.

Intramuscular atropine sulfate in children: Comparison of injection sites

In children undergoing inhaled induction of anesthesia with halothane who suffer bradycardia, submental glossal injection of atropine may result in more rapid onset of vagolysis than traditional intramuscular sites.We compared the intervals between injection and onset of heart rate acceleration (tHR [arrow up]) after intramuscular injection of atropine into the deltoid, vastus lateralis, and glossa in children between 1 mo and 10 yr of age scheduled for elective surgery. The tHR [arrow up] was determined by measuring the interval between atropine injection and the time point at which the slope of the heart rate curve initially became positive. To ensure that the drug had taken effect before surgical stimulation, heart rate observation was continued until it increased at least 5% above baseline with evidence of continuing acceleration. Anesthesia was induced in all subjects by mask with nitrous oxide and halothane. After tracheal intubation, constant inspired concentrations of the anesthetics were administered for 3 min. While heart rate was monitored, atropine (0.02 mg/kg) was injected into one of the three sites. Each patients end-tidal anesthetic concentrations were recorded, and minimum alveolar anesthetic concentrations (MAC) were subsequently calculated and adjusted for age. The tHR [arrow up] was recorded and averaged for each group. The study groups did not differ by age, weight, end-tidal anesthetic concentrations, age-adjusted MAC, or heart rate at the time atropine was administered. After submental glossal injection (n = 11), tHR [arrow up] increase was fastest (3.0 +/- 1.1 min) and was significantly faster than that found with deltoid injection (n = 16; 4.4 +/- 1.1 min) or vastus lateralis injection (n = 8; 6.4 +/- 2.4 min) (P < 0.05 compared with both). The tHR [arrow up] also differed significantly between the deltoid and the vastus lateralis (P < 0.05). We conclude that submental glossal injection of atropine results in a more rapid onset of vagolysis than injection at traditional intramuscular sites. (Anesth Analg 1997;84:54-8)

Ventilator Y-Piece Pressure Compared with Intratracheal Airway Pressure in Healthy Intubated Children

AbstractObjective. Compare airway pressure measurements at the ventilator Y-piece of the breathing circuit (PY) to intratracheal pressure measured at the distal end (PT) of the endotracheal tube (ETT) during mechanical ventilation and spontaneous breathing of intubated children. Methods. Thirty children (age range 29 days to 5 years) receiving general anesthesia were intubated with an ETT incorporating a lumen embedded in its sidewall that opened at the distal end to measure PT. Peak inflation pressure (PIP) was measured at PY and PT during positive pressure ventilation. Just before extubation, all measurements were repeated and imposed resistive work of breathing (WOBi) was calculated at both sites while breathing spontaneously. Results. Average PIP was approximately 25% greater at PY (19.7n± 3.4 cm H2O) vs. PT (15.0 ± 2.9 cm H2O), p < 0.01. During spontaneous inhalation PT was 59% lower ({bond}8.5 ± 4.0 cm H2O) vs. PY ({bond}3.5 ± 2.0 cm H2O), p < 0.01. WOBi measured at PY (0.10 ± 0.02 Joule/L) was 86% less than WOBi measured at PT (0.70 ± 0.40 Joule/L), p < 0.01. Conclusions. In healthy children PY significantly overestimates PIP in the trachea during positive pressure ventilation and underestimates the intratracheal airway pressure during spontaneous inhalation. During positive pressure ventilation PT better assesses the pressure generated in the airways and lungs compared to PY because PT also includes the difference in airway pressure across the ETT tube due to resistance. During spontaneous inhalation, PT reflects the series resistance of the ETT and ventilator circuit, while PY reflects only the resistance of the ventilator circuit, accounting for the smaller decreases in pressure. Additionally, PY underestimates the total WOBi load on the respiratory muscles. Thus, PT is a more accurate reflection of pulmonary airway pressures than PY and suggests that it should be incorporated into ventilator systems to more accurately trigger the ventilator and to reduce work of breathing.

Prolonged neuromuscular blockade for relaxation in two pediatric intensive care patients.

Newer neuromuscular blocking drugs provide optimum blockade and can facilitate ventilation, yet if they are discontinued, they allow predictable reversal. This article documents the use of these drugs in the treatment of two pediatric intensive care unit patients who had different physiologic problems and pharmacologic needs and who were ventilator dependent for a prolonged period. In each case, neuromuscular blockade significantly facilitated ventilation and allowed time for treatment of the underlying pathology without deleterious pharmacologic side effects resulting in a favorable outcome for both patients. The article discusses some of the unique pharmacologic properties of these drugs and the rationale for their use.

Prolonged use of high-frequency jet ventilation for a pediatric patient.

A 10-yr-old boy who developed postoperative respiratory failure with evidence of significant barotrauma was treated with high-frequency jet ventilation (HFJV). HFJV reduced peak inflation pressure, enhanced oxygenation, and improved ventilation. The patient could not be weaned from HFJV by decreasing drive pressure. Instead, he was successfully weaned by decreasing the HFJV rate to 80 cycle/min and then switching to conventional intermittent mandatory ventilation at initially similar rate and pressure levels.