Showing papers in "Anesthesiology in 1997"
TL;DR: The bispectral index, a value derived from the electroencephalograph (EEG), has been proposed as a measure of anesthetic effect and its utility is important to establish its utility.
Abstract: Background:The bispectral index (BIS), a value derived from the electroencephalograph (EEG), has been proposed as a measure of anesthetic effect. To establish its utility for this purpose, it is important to determine the relation among BIS, measured drug concentration, and increasing levels of seda
1,222 citations
TL;DR: The aim of this study was to determine the influence of age and gender on the pharmacokinetics and pharmacodyn of fentanyl, alfent anil, and sufentanil.
Abstract: BackgroundPrevious studies have reported conflicting results concerning the influence of age and gender on the pharmacokinetics and pharmacodynamics of fentanyl, alfentanil, and sufentanil. The aim of this study was to determine the influence of age and gender on the pharmacokinetics and pharmacodyn
1,052 citations
TL;DR: The incidence of cardiac arrest and neurologic injury related to regional anesthesia were very low, but both were more than three SDs greater after spinal anesthesia than after other regional procedures.
Abstract: BACKGROUND Serious complications related to regional anesthesia have previously been described primarily in case reports and retrospective surveys. The authors prospectively evaluated a multicenter series of regional anesthetics, using preplanned criteria to measure the incidence and characteristics of associated serious complications. METHODS Requests were sent to 4,927 French anesthesiologists in advance of a subsequent 5-month study period. Participating anesthesiologists were asked for detailed reports of serious complications occurring during or after regional anesthetics performed by them during the study interval. Details regarding each complication then were obtained via a second questionnaire. RESULTS The number of responding anesthesiolgists was 736. The number of regional anesthetics performed was 103,730, corresponding to 40,640 spinal anesthetics, 30,413 epidural anesthetics, 21,278 peripheral nerve blocks, and 11,229 intravenous regional anesthetics. Reports of 98 severe complications were received, with follow-up information being obtained for 97. In 89 cases, complications were attributed fully or partially to regional anesthesia. Thirty-two cardiac arrests, seven of which were fatal, occurred during the study. Of these, 26 occurred during spinal anesthesia, with 6 being fatal, 3 occurred during epidural anesthesia, and 3 more occurred during peripheral blocks. The higher incidence of cardiac arrest during spinal anesthesia (6.4 +/- 1.2 per 10,000 patients) compared with all other regional anesthesia (1.0 +/- 0.4 per 10,000 patients) was statistically significant (P < 0.05). Of 34 neurologic complications (radiculopathy, cauda equina syndrome, paraplegia), 21 were associated either with paresthesia during puncture (n = 19) or with pain during injection (n = 2), suggesting nerve trauma or intraneural injection. Twelve patients who had neurologic complications after spinal anesthetics had no paresthesia during needle placement and no pain on injection. Of these 12 patients (7 with radiculopathy and 5 with cauda equina syndrome), 9 received intrathecal hyperbaric lidocaine, 5%. The incidence of neurologic injury was significantly greater after spinal anesthesia (6 +/- 1 per 10,000 cases; P < 0.05) than after each of the other types of regional procedures (1.6 +/- 0.5 per 10,000 cases for the weighted average). Seizures attributed to elevated serum levels of local anesthetics occurred in 23 patients, but none suffered a cardiac arrest. CONCLUSIONS (1) The incidence of cardiac arrest and neurologic injury related to regional anesthesia were very low, but both were more than three SDs greater after spinal anesthesia than after other regional procedures. (2) Two thirds of the patients with neurologic deficits had either a paresthesia during needle placement or pain on injection. (3) Seventy-five percent of the neurologic deficits after nontraumatic spinal anesthesia occurred in patients who had received hyperbaric lidocaine, 5%.
1,028 citations
TL;DR: It is indicated that the use of BIS may be valuable in guiding the administration of propofol intraoperatively and in improving recovery after balanced anesthesia.
Abstract: Background:The bispectral index (BIS), a parameter derived from the electroencephalograph (EEG), has been shown to correlate with increasing sedation and loss of consciousness. This study determined whether addition of BIS monitoring to standard anesthetic practice results in improvements in the con
727 citations
TL;DR: A quantitative score that can be used to evaluate intubating conditions and techniques with the aim of determining the relative values predictive factors of intubation difficulty and of the techniques used to decrease such difficulties is developed.
Abstract: Background:A quantitative scale of intubation difficulty would be useful for objectively comparing the complexity of endotracheal intubations. The authors have developed a quantitative score that can be used to evaluate intubating conditions and techniques with the aim of determining the relative va
651 citations
TL;DR: The incidence of anesthesia‐related deaths during obstetric delivery in the United States from 1979–1990 is decreasing, however, and deaths due to general anesthesia remain stable in number and hence account for an increased proportion of total deaths.
Abstract: BackgroundAnesthesia-related complications are the sixth leading cause of pregnancy-related death in the United States. This study reports characteristics of anesthesia-related deaths during obstetric delivery in the United States from 1979–1990.MethodsEach state reports deaths that occur within 1 y
628 citations
TL;DR: Age and LBM are significant demographic factors that must be considered when determining a dosage regimen for remifentanil, and simulations suggest that the time required for a decrease in effect site concentrations will be more variable in the elderly.
Abstract: BackgroundThe pharmacokinetics and pharmacodynamics of remifentanil were studied in 65 healthy volunteers using the electroencephalogram (EEG) to measure the opioid effect. [1] In a companion article, the authors developed complex population pharmacokinetic and pharmacodynamic models that incorporat
615 citations
TL;DR: Maintaining core normothermia decreases the duration of postanesthetic recovery and may, therefore, reduce costs of care.
Abstract: Background:Intraoperative hypothermia is common and persists for several hours after surgery. Hypothermia may prolong immediate recovery by augmenting anesthetic potency, delaying drug metabolism, producing hemodynamic instability, or depressing cognitive function. Accordingly, the authors tested th
505 citations
TL;DR: Isoflurane directly preconditions myocardium against infarction via activation of KATP channels in the absence of hemodynamic effects and exhibits acute memory of preconditioning in vivo.
Abstract: BACKGROUND The authors tested the hypothesis that isoflurane directly preconditions myocardium against infarction via activation of K(ATP) channels and that the protection afforded by isoflurane is associated with an acute memory phase similar to that of ischemic preconditioning. METHODS Barbiturate-anesthetized dogs (n = 71) were instrumented for measurement of systemic hemodynamics. Myocardial infarct size was assessed by triphenyltetrazolium chloride staining. All dogs were subjected to a single prolonged (60 min) left anterior descending coronary artery (LAD) occlusion followed by 3 h of reperfusion. Ischemic preconditioning was produced by four 5-min LAD occlusions interspersed with 5-min periods of reperfusion before the prolonged LAD occlusion and reperfusion. The actions of isoflurane to decrease infarct size were examined in dogs receiving 1 minimum alveolar concentration (MAC) isoflurane that was discontinued 5 min before prolonged LAD occlusion. The interaction between isoflurane and ischemic preconditioning on infarct size was evaluated in dogs receiving isoflurane before and during preconditioning LAD occlusions and reperfusions. To test whether the cardioprotection produced by isoflurane can mimic the acute memory of ischemic preconditioning, isoflurane was discontinued 30 min before prolonged LAD occlusion and reperfusion. The mechanism of isoflurane-induced cardioprotection was evaluated in two final groups of dogs pretreated with glyburide in the presence or absence of isoflurane. RESULTS Myocardial infarct size was 25.3 +/- 2.9% of the area at risk during control conditions. Isoflurane and ischemic preconditioning produced significant (P < 0.05) and equivalent reductions in infarct size (ischemic preconditioning alone, 9.6 +/- 2.0; isoflurane alone, 11.8 +/- 2.7; isoflurane and ischemic preconditioning, 5.1 +/- 1.9%). Isoflurane-induced reduction of infarct size also persisted 30 min after discontinuation of the anesthetic (13.9 +/- 1.5%), independent of hemodynamic effects during LAD occlusion. Glyburide alone had no effect on infarct size (28.3 +/- 3.9%), but it abolished the protective effects of isoflurane (27.1 +/- 4.6%). CONCLUSIONS Isoflurane directly preconditions myocardium against infarction via activation of K(ATP) channels in the absence of hemodynamic effects and exhibits acute memory of preconditioning in vivo.
496 citations
TL;DR: Titrating desflurane and sevoflurane using the BIS monitor decreased their utilization and contributed to a faster emergence from anesthesia in outpatients undergoing laparoscopic tubal ligation procedures.
Abstract: Background:The bispectral (BIS) index has previously been shown to be a quantifiable measure of the sedative and hypnotic effects of anesthetic drugs. This study was designed to assess the effect of BIS monitoring on the utilization of volatile anesthetics and their recovery profiles after ambulator
441 citations
TL;DR: It is concluded that cuffed endotracheal tubes may be used routinely during controlled ventilation in full‐term newborns and children during anesthesia.
Abstract: BackgroundUncuffed endotracheal tubes are routinely used in young children. This study tests a formula for selecting appropriately sized cuffed endotracheal tubes and compares the use of cuffed versus uncuffed endotracheal tubes for patients whose lungs are mechanically ventilated during anesthesia.
TL;DR: If the risk of PONV is very high, for every 100 patients receiving an adequate dose of ondansetron 20 patients will not vomit and three will have a headache who would not have had these adverse effects without the drug.
Abstract: Objective: The authors reviewed efficacy and safety data for ondansetron for preventing postoperative nausea and vomiting (PONV). Methods: Systematically searched, randomized, controlled trials (obtained through MEDLINE, EMBASE, Biological Abstracts, manufacturer's database, manual searching of journals, and article reference lists) were analyzed. Relevant end points were prevention of early PONV (within 6 h after surgery) and late PONV (within 48 h) and adverse effects. Relative benefit and number-needed-to-treat were calculated. The number-needed-to-treat indicated how many patients had to be exposed to ondansetron to prevent PONV in one of them who would have vomited or been nauseated had he or she received placebo. Results: Fifty-three trials were found that had data from 7,177 patients receiving 24 different ondansetron regimens and from 5,712 controls receiving placebo or no treatment. Average early and late PONV incidences without ondansetron were 40% and 60%, respectively. There was a dose response for oral and intravenous ondansetron. Best number-needed-to-treat to prevent PONV with the best documented regimens was between 5 and 6. This was achieved with an intravenous dose of 8 mg and an oral dose of 16 mg. Antivomiting efficacy was consistently better than antinausea efficacy. Efficacy in children was poorly documented. Ondansetron significantly increased the risk for elevated liver enzymes (number-needed-to-harm was 31) and headache (number-needed-to-harm was 36). Conclusions: If the risk of PONV is very high, for every 100 patients receiving an adequate dose of ondansetron 20 patients will not vomit who would have vomited had they received placebo. The antinausea effect is less pronounced. Of these 100, three will have elevated liver enzymes and three will have a headache who would not have had these adverse effects without the drug.
TL;DR: Vecuronium‐induced partial paralysis cause pharyngeal dysfunction and increased risk for aspiration at mechanical adductor pollicis TOF ratios < 0.90, and the upper esophageal sphincter muscle is more sensitive to vecuronium than is the pharynGEal constrictor muscle.
Abstract: BACKGROUND: Functional characteristics of the pharynx and upper esophagus, including aspiration episodes, were investigated in 14 awake volunteers during various levels of partial neuromuscular block Pharyngeal function was evaluated using videoradiography and computerized pharyngeal manometry during contrast bolus swallowing METHODS: Measurements of pharyngeal constrictor muscle function (contraction amplitude, duration, and slope), upper esophageal sphincter muscle resting tone, muscle coordination, bolus transit time, and aspiration under fluoroscopic control (laryngeal or tracheal penetration) were made before (control measurements) and during a vecuronium-induced partial neuromuscular paralysis, at fixed intervals of mechanical adductor pollicis muscle train-of-four (TOF) fade; that is, at TOF ratios of 060, 070, 080, and after recovery to a TOF ratio > 090 RESULTS: Six volunteers aspirated (laryngeal penetration) at a TOF ratio 090 or during control recording Pharyngeal constrictor muscle function was not affected at any level of paralysis The upper esophageal sphincter resting tone was significantly reduced at TOF ratios of 060, 070, and 080 (P 090 is reached The upper esophageal sphincter muscle is more sensitive to vecuronium than is the pharyngeal constrictor muscle
TL;DR: Sevoflurane provided quicker emergence and early recovery compared with halothane, but the incidence of delirium was greater in preschool boys after sevofl Lurane.
Abstract: Background:In the authors' clinical experience, preschool children are more likely to show delirium after sevoflurane than are older children.Methods:Sixty-three preschool boys aged 3–5 yr (classified as American Society of Anesthesiologists [ASA] physical status I), and 53 school-age boys aged 6–10
TL;DR: Cardioprotection by volatile anesthetics depended on both adenosine receptors and protein kinase C, and thus is similar to the mechanism of protection seen with ischemic preconditioning, and was independent of the hypotensive effect of the inhalational agents.
Abstract: Background The influence of anesthetic agents on the infarction process in the ischemic myocardium is unclear. This study evaluated the effects of three intravenous and three inhalational anesthetic agents on myocardial infarction within a quantified ischemic risk zone in rabbit hearts subjected to a standardized regional ischemia-reperfusion insult. Methods Both in vitro and in situ rabbit models were used to investigate the effects of anesthetic agents on infarct size. In all rabbits the heart was exposed and a coronary artery surrounded with a suture to form a snare for subsequent occlusion. In in situ preparations, both intravenous and inhalational agents were tested, whereas only the latter were used in isolated hearts. Infarct size was determined by triphenyltetrazolium chloride staining. To determine whether an adenosine-mediated protective mechanism was involved, 8-(p-sulfophenyl)theophylline, an adenosine receptor blocker, was added to halothane-treated isolated hearts. Adenosine concentration in the coronary effluent was also measured in isolated hearts exposed to halothane. In other protocols, chelerythrine, a highly selective protein kinase C inhibitor, was administered to both halothane-treated and untreated isolated hearts. Results Infarcts in the three in situ groups anesthetized with halothane, enflurane, and isoflurane were about one half as large as infarcts in rabbits that underwent anesthesia with pentobarbital, ketamine-xylazine, or propofol. Volatile anesthetics also protected isolated hearts by a similar amount. Both adenosine receptor blockade and chelerythrine abolished cardioprotection from halothane in isolated hearts. Halothane treatment did not increase adenosine release. Conclusions The volatile anesthetics tested protected the ischemic rabbit heart from infarction, in contrast to the three intravenous agents tested. Protection was independent of the hypotensive effect of the inhalational agents because halothane also protected isolated hearts, in which changing vascular tone is not an issue and coronary perfusion pressure is constant. Cardioprotection by volatile anesthetics depended on both adenosine receptors and protein kinase C, and thus is similar to the mechanism of protection seen with ischemic preconditioning.
TL;DR: Recovery of the train-of-four (TOF) ratio to a value > 0.70 is synonymous with adequate return of neuromuscular function, but there is little information available concerning the subjective experience that accompanies residual neuromUScular block wherein the TOF ratio is in the range of 0.
Abstract: Background:Recovery of the train-of-four (TOF) ratio to a value > 0.70 is synonymous with adequate return of neuromuscular function, but there is little information available concerning the subjective experience that accompanies residual neuromuscular block wherein the TOF ratio is in the range of 0
TL;DR: Observations are consistent with a model whereby ketamine inhibits the NMDA receptor by two distinct mechanisms: (1) Ketamine blocks the open channel and thereby reduces channel mean open time, and (2) ketamine decreases the frequency of channel opening by an allosteric mechanism.
Abstract: Background:The N-methyl-D-aspartate (NMDA) subtype of glutamate receptor is blocked by ketamine, and this action likely contributes to ketamine's anesthetic and analgesic properties. Previous studies suggest that ketamine occludes the open channel by binding to a site located within the channel pore
TL;DR: Critical Hemoglobin Desaturation Will Occur before Return to an Unparalyzed State following 1 mg/kg Intravenous Succinylcholine.
Abstract: Critical Hemoglobin Desaturation Will Occur before Return to an Unparalyzed State following 1 mg/kg Intravenous Succinylcholine Jonathan Benumof;Rachel Dagg;Reuben Benumof; Anesthesiology
TL;DR: The electroencephalogram‐derived bispectral index (BIS) can be used to predict probability of recovery of consciousness after a single injection of either thiopental or propofol.
Abstract: BackgroundCurrently, there exists no effective monitor that can predict the probability of a patient being conscious during general anesthesia. The electroencephalogram-derived bispectral index (BIS) is a promising new method to assess anesthetic adequacy. This study used the BIS to predict the prob
TL;DR: Naloxone infusion at 0.25 micro gram [center dot] kg sup ‐1 [ center dot] h sup 1 not only attenuates these side effects but appears to reduce postoperative (beyond 4–8 h) opioid requirements.
Abstract: Background:A naloxone infusion is effective in reducing epidural and intrathecal opioid-related side effects. The use of naloxone infusion concomitant with intravenous morphine patient-controlled analgesia (PCA) has not been evaluated, probably because of an expected direct antagonism of the systemi
TL;DR: In contrast to SNP infusions, prop ofol infusions into the brachial artery of conscious persons caused no significant vascular responses, despite the presence of therapeutic plasma concentrations of propofol within the forearm.
Abstract: BackgroundAnesthetic induction and maintenance with propofol are associated with decreased blood pressure that is, in part, due to decreased peripheral resistance. Several possible mechanisms whereby propofol could reduce peripheral resistance include a direct action of propofol on vascular smooth m
TL;DR: The incidence of neurologic complications occurring after thoracic epidural catheterization was studied and the risk:benefit ratio of thoracIC epidural analgesia is controversial.
Abstract: BackgroundDue to potential neurologic sequelae, the risk:benefit ratio of thoracic epidural analgesia is controversial. Surprisingly, however, few available data address neurologic complications. The incidence of neurologic complications occurring after thoracic epidural catheterization was studied
TL;DR: The PCIA technique was uncomplicated and provided better pain relief than PCA during the first 18 h after operation, and patient satisfaction was superior in the PCIA group.
Abstract: Background:The authors compared patient-controlled interscalene analgesia (PCIA) with local anesthetics with intravenous patient-controlled analgesia (PCA) with opioids to manage postoperative pain after major shoulder surgery.Methods:Forty patients scheduled for elective major shoulder surgery were
TL;DR: Intraoperative intravenous infusion of dexmedetomidine to patients undergoing coronary artery revascularization decreased intraoperative sympathetic tone and attenuated hyperdynamic responses to anesthesia and surgery but increased the propensity toward hypotension.
Abstract: BackgroundAlpha2 -Adrenergic agonists decrease sympathetic tone with ensuing attenuation of neuroendocrine and hemodynamic responses to anesthesia and surgery. The effects of dexmedetomidine, a highly specific alpha2 -adrenergic agonist, on these responses have not been reported in patients undergoi
TL;DR: The results suggest that ketamine may not adversely alter cerebral hemodynamics of mechanically ventilated head‐trauma patients sedated with propofol, and encouraging results should be confirmed in larger groups of similar patients.
Abstract: BACKGROUND: The potential adverse effects of ketamine in neurosurgical anesthesia have been well established and involve increased intracranial pressure (ICP) and cerebral blood flow. However, reexamination of ketamine is warranted because data regarding the effects of ketamine on cerebral hemodynamics are conflicting. METHODS: Eight patients with traumatic brain injury were studied. In all patients, ICP monitoring was instituted before the study. Control of ICP (less than 25 mmHg), hemodynamic values, and blood gas tension (partial pressure of carbon dioxide in arterial blood between 35-38 mmHg) was obtained with propofol infusion (3 mg x kg(-1) x h(-1)) and mechanical ventilation. The effects of three doses of ketamine, 1.5, 3, and 5 mg/kg, respectively, on ICP, cerebral perfusion pressure, jugular vein bulb oxygen saturation, middle cerebral artery blood flow velocity, and electric activity of the brain (EEG) were measured. The three doses were administered intravenously at 6-h intervals over 30 s through a central venous line. Systemic and cerebral hemodynamics and end-tidal carbon dioxide were continuously monitored and recorded at 1-min intervals throughout the 30-min study periods. RESULTS: Ketamine, in all three doses studied (1.5, 3, and 5 mg/kg) was associated with a significant decrease in ICP (mean +/- SD: 2 +/- 0.5 mmHg [P < 0.05], 4 +/- 1 mmHg [P < 0.05], and 5 +/- 2 mmHg [P < 0.05]) among the study patients regardless of the ketamine dose used. There were no significant differences in cerebral perfusion pressure, jugular vein bulb oxygen saturation, and middle cerebral artery blood flow velocity. Ketamine induced a low-amplitude fast-activity electroencephalogram, with marked depression, such as burst suppression. CONCLUSIONS: These results suggest that ketamine may not adversely alter cerebral hemodynamics of mechanically ventilated head-trauma patients sedated with propofol. These encouraging results should be confirmed in larger groups of similar patients.
TL;DR: The alpha4beta2 receptor is affected by isoflurane more potently than the most sensitive GABAA or glycine receptor that has been reported, whereas the alpha7 homomeric receptor is not affected by either anesthetic.
Abstract: Background:The mechanisms of action of general anesthetics are not completely understood. Many general anesthetics are reported to potentiate gamma-aminobutyric acid (GABAA) and glycine receptors in the central nervous system (CNS) and to inhibit the muscle-type nicotinic acetylcholine receptor (nAC
TL;DR: The data clarify that the anesthetic state evident in the living human brain during unresponsiveness induced with isoflurane is associated with a global, fairly uniform, whole‐brain glucose metabolic reduction of 46 +/‐ 11%.
Abstract: BackgroundAlthough the anesthetic effects of the intravenous anesthetic agent propofol have been studied in the living human brain using brain imaging technology, the nature of the anesthetic state evident in the human brain during inhalational anesthesia remains unknown To examine this issue, the
TL;DR: At equal sedation, propofol produces the same degree of memory impairment as midazolam while thiopental has mild memory effects whereas fentanyl has none.
Abstract: Background:The authors evaluated the effects of midazolam, propofol, thiopental, and fentanyl on volunteer participants' memory for words and pictures at equisedative concentrations.Methods:Sixty-seven healthy volunteers were randomized to receive intravenous infusions of midazolam (n = 11), propofo
TL;DR: Although there is considerable uncertainty about the physiologic roles that neuronal nAChRs play in the central nervous system, their extraordinary sensitivity to general anesthetics, particularly the inhalational agents, suggests they may mediate some of the effects of generalAnesthetics at surgical, or even subanesthetic, concentrations.
Abstract: Background:Nicotinic acetylcholine receptors (nAChRs) are members of a superfamily of fast neurotransmitter-gated receptor channels that includes the gamma-aminobutyric acidA (GA-BAA), glycine and serotonin type 3 (5-HT3) receptors. Most previous work on the interactions of general anesthetics with