Showing papers in "Anesthesiology in 1995"
1,107 citations
TL;DR: Complications were not increased when intubations were accomplished without the supervision of an attending physician as long as the intubation was carried out or supervised by an individual skilled in airway management.
Abstract: BackgroundHospitalized patients outside of the operating room frequently require emergency airway management. This study investigates complications of emergency airway management in critically ill adults, including: (1) the incidence of difficult and failed intubation; (2) the frequency of esophagea
607 citations
TL;DR: This study highlights the need to select patients suitable for vaginal or laparoscopic mesh placement for analgesia prior to and after colonic surgery on the basis of prior history and once they provide informed consent for surgery.
Abstract: BackgroundChoice of perioperative analgesia may affect the rate of recovery of gastrointestinal function and thus duration and cost of hospitalization after colonic surgery.
464 citations
TL;DR: The goal of this study was to elucidate the proportion of anesthesia costs relative to perioperative costs as determined by charges and actual costs.
Abstract: BackgroundMany health-care institutions are emphasizing cost reduction programs as a primary tool for managing profitability. The goal of this study was to elucidate the proportion of anesthesia costs relative to perioperative costs as determined by charges and actual costs.
433 citations
TL;DR: The analysis suggests that the probability of apnea in non-anemic infants free of recovery-room apnea is not less than 5%, with 95% statistical confidence until postconceptual age was 48 weeks with gestational age 35 weeks.
Abstract: BackgroundControversy exists as to the risk for postoperative apnea in former preterm infants. The conclusions of published studies are limited by the small number of patients.MethodsThe original data from eight prospective studies were subject to a combined analysis. Only patients having inguinal h
426 citations
425 citations
TL;DR: Despite a growing trend in pain management, increased professional and public awareness including the establishment of pain management programs and public and patient education is needed to reduce the incidence and severity of postoperative pain.
Abstract: Background : The objective of the survey was to assess the status of acute pain management in U.S. hospitals and attitudes of adults in the U.S. toward postoperative pain management, information that has not been previously available. Methods : Two telephone questionnaire surveys were conducted. U.S. hospital participants, including 100 teaching hospitals (acute care hospitals with a residency program and/or university affiliation), 100 nonteaching (community) hospitals with fewer than 200 beds, and 100 nonteaching (community) hospitals with 200 beds or more were interviewed regarding current and future pain management programs and related topics. Adult participants in 500 U.S. households were interviewed on attitudes and experiences with postoperative pain and its management. Results : Forty-two percent of the hospitals have acute pain management programs, and an additional 13% have plans to establish an acute pain management program. Seventy-seven percent of adults believe that it is necessary to experience some pain after surgery. Fifty-seven percent of those who had surgery cited concern about pain after surgery as their primary fear experienced before surgery. Seventy-seven percent of adults reported pain after surgery, with 80% of these experiencing moderate to extreme pain. Conclusions : Despite a growing trend in pain management, increased professional and public awareness including the establishment of pain management programs and public and patient education is needed to reduce the incidence and severity of postoperative pain.
410 citations
TL;DR: This data indicates that spontaneous hypothermia occurs frequently during surgery and may have adverse effects on the cardiovascular system, and the mechanisms responsible for the cardiovascular manifestations ofhypothermia are unclear.
Abstract: BackgroundUnintended hypothermia occurs frequently during surgery and may have adverse effects on the cardiovascular system. Although the mechanisms responsible for the cardiovascular manifestations of hypothermia are unclear, it is possible that they are sympathetically mediated. In this prospectiv
381 citations
TL;DR: The dynamic rate of regulation (dROR) was assessed from the rate of change in cerebrovascular resistance (MABP/Vmca) with the blood pressure decreases using computer modeling, whereas the static rate ofregulation (sROR)was assessed fromthe change in Vmca with the change in MABP.
Abstract: Background Although inhalation anesthetic agents are thought to impair cerebral autoregulation more than intravenous agents, there are few controlled studies in humans. Methods In the first group (n = 24), dynamic autoregulation was assessed from the response of middle cerebral artery blood flow velocity (Vmca) to a transient step decrease in mean arterial blood pressure (MABP). The transient hypotension was induced by rapid deflation of thigh cuffs after inflation for 3 min. In the second group (n = 18), static autoregulation was studied by observing Vmca in response to a phenylephrine-induced increase in MABP. All patients were studied during fentanyl (3 micrograms.kg-1.h-1)/nitrous oxide (70%) anesthesia, followed by, in a randomized manner, isoflurane, desflurane, or propofol in a low dose (0.5 MAC or 100 micrograms.kg-1.min-1) and a high dose (1.5 MAC or 200 micrograms.kg-1.min-1). The dynamic rate of regulation (dROR) was assessed from the rate of change in cerebrovascular resistance (MABP/Vmca) with the blood pressure decreases using computer modeling, whereas the static rate of regulation (sROR) was assessed from the change in Vmca with the change in MABP. Results Low-dose isoflurane delayed (dROR decreased) but did not reduce the autoregulatory response (sROR intact). Low-dose desflurane decreased both dROR and sROR. During 1.5 MAC isoflurane or desflurane, autoregulation was ablated (both dROR and sROR impaired). Neither dROR nor sROR changed with low- or high-dose propofol. Conclusions At 1.5 MAC, isoflurane and desflurane impaired autoregulation whereas propofol (200 micrograms.kg-1.min-1) preserved it.
360 citations
TL;DR: The composition of inspiratory gas plays an important role in the recurrence of collapse of previously reexpanded atelectatic lung tissue during general anesthesia in patients with healthy lungs and appears to be independent of the change in the compliance of the respiratory system.
Abstract: BACKGROUND:Atelectasis, an important cause of impaired gas exchange during general anesthesia, may be eliminated by a vital capacity maneuver. However, it is not clear whether such a maneuver will ...
344 citations
TL;DR: The context-sensitive half-time, rather than the terminal elimination half-life, has been proposed as a more clinically relevant measure of decreasing drug concentration after a constant infusion of a given duration.
Abstract: BackgroundThe context-sensitive half-time, rather than the terminal elimination half-life, has been proposed as a more clinically relevant measure of decreasing drug concentration after a constant infusion of a given duration. The context-sensitive half-time is derived from computer modelling using
TL;DR: The metabolic pattern evident during anesthesia was reproducible and differed from that seen in the awake condition, and suggest PET may be useful for investigating the mechanisms of anesthesia in humans.
Abstract: BACKGROUND Although the effects of propofol on cerebral metabolism have been studied in animals, these effects have yet to be directly examined in humans. Consequently, we used positron emission tomography (PET) to demonstrate in vivo the regional cerebral metabolic changes that occur in humans during propofol anesthesia. METHODS Six volunteers each underwent two PET scans; one scan assessed awake-baseline metabolism, and the other assessed metabolism during anesthesia with a propofol infusion titrated to the point of unresponsiveness (mean rate +/- SD = 7.8 +/- 1.5 mg.kg-1.h-1). Scans were obtained using the 18fluorodeoxyglucose technique. RESULTS Awake whole-brain glucose metabolic rates (GMR) averaged 29 +/- 8 mumoles.100 g-1.min-1 (mean +/- SD). Anesthetized whole-brain GMR averaged 13 +/- 4 mumoles.100 g-1.min-1 (paired t test, P < or = 0.007). GMR decreased in all measured areas during anesthesia. However, the decrease in GMR was not uniform. Cortical metabolism was depressed 58%, whereas subcortical metabolism was depressed 48% (P < or = 0.001). Marked differences within cortical regions also occurred. In the medial and subcortical regions, the largest percent decreases occurred in the left anterior cingulate and the inferior colliculus. CONCLUSION Propofol produced a global metabolic depression on the human central nervous system. The metabolic pattern evident during anesthesia was reproducible and differed from that seen in the awake condition. These findings are consistent with those from previous animal studies and suggest PET may be useful for investigating the mechanisms of anesthesia in humans.
TL;DR: This work has shown that maintaining constant cutaneous temperature is best kept constant when determining response thresholds because both skin and core temperatures contribute to thermoregulatory control.
Abstract: BackgroundSkin temperature is best kept constant when determining response thresholds because both skin and core temperatures contribute to thermoregulatory control. In practice, however, it is difficult to evaluate both warm and cold thresholds while maintaining constant cutaneous temperature. A re
TL;DR: This study evaluated the in vivo effect of morphine on human peripheral blood immune functions and found that morphine alters in vivo immunity in humans in a manner similar to that of heroin.
Abstract: BackgroundOpioids are used by patients who have conditions ranging from the acute pain of surgery and chronic cancer pain to substance abuse. Despite their widespread use and considerable experimental data about them, little is known about how opioids may alter in vivo immunity in humans. This study
TL;DR: Quantitative observations of the onset, offset, and intensity of differential functional impairment or block over time will make it possible to establish the doses and conditions for local anesthetics that result in differential nerve block and will permit comparison of these changes among different drugs and "clinical" protocols.
Abstract: BackgroundQuantitative behavioral testing is necessary to establish a reproducible measure of differential functional blockade during regional anesthesia. Methods for assessment of the neurologic status (mental status, posture, gait, proprioception, motor function, autonomic function, and nociceptio
TL;DR: C cautious examination of intrathecal neostigmine alone and in combination with other agents for analgesia is warranted because no unexpected or dangerous side effects occurred and effects in humans are consistent with studies in animals.
Abstract: Background In dogs, sheep, and rats, spinal neostigmine produces analgesia alone and enhances analgesia from alpha 2-adrenergic agonists. This study assesses side effects and analgesia from intrathecal neostigmine in healthy volunteers. Methods After institutional review board approval and informed consent, 28 healthy volunteers were studied. The first 14 volunteers received neostigmine (50-750 micrograms) through a #19.5 spinal needle followed by insertion of a spinal catheter. The remaining 14 volunteers received neostigmine through a #25 or #27 spinal needle without a catheter. Safety measurements included blood pressure, heart rate, oxyhemoglobin saturation, end-tidal carbon dioxide, neurologic evaluation, and computer tests of vigilance and memory. Analgesia in response to ice water immersion was measured. Results Neostigmine (50 micrograms) through the #19.5 needle did not affect any measured variable. Neostigmine (150 micrograms) caused mild nausea, and 500-750 micrograms caused severe nausea and vomiting. Neostigmine (150-750 micrograms) produced subjective leg weakness, decreased deep tendon reflexes, and sedation. The 750-micrograms dose was associated with anxiety, increased blood pressure and heart rate, and decreased end-tidal carbon dioxide. Neostigmine (100-200 micrograms) in saline, injected through a #25 or #27 needle, caused protracted, severe nausea, and vomiting. This did not occur when dextrose was added to neostigmine. Neostigmine by either method of administration reduced visual analog pain scores to immersion of the foot in ice water. Conclusions The incidence and severity of these adverse events from intrathecal neostigmine appears to be affected by dose, method of administration, and baricity of solution. These effects in humans are consistent with studies in animals. Because no unexpected or dangerous side effects occurred, cautious examination of intrathecal neostigmine alone and in combination with other agents for analgesia is warranted.
TL;DR: Evaluated regional body heat content and the extent to which core hypothermia after induction of anesthesia resulted from altered heat balance and internal heat redistribution to find out the relative contributions of each mechanism.
Abstract: BACKGROUND Core hypothermia after induction of epidural anesthesia results from both an internal core-to-peripheral redistribution of body heat and a net loss of heat to the environment. However, the relative contributions of each mechanism remain unknown. The authors thus evaluated regional body heat content and the extent to which core hypothermia after induction of anesthesia resulted from altered heat balance and internal heat redistribution. METHODS Twelve minimally clothed male volunteers were evaluated in a approximately 22 degrees C environment for 2.5 control hours before induction of epidural anesthesia and for 3 subsequent hours. Epidural anesthesia produced a bilateral sympathetic block in only six volunteers, and only their results are reported. Shivering, when observed, was treated with intravenous meperidine. Overall heat balance was determined from the difference between cutaneous heat loss (thermal flux transducers) and metabolic heat production (oxygen consumption). Arm and leg tissue heat contents were determined from 19 intramuscular needle thermocouples, 10 skin temperatures, and "deep" foot temperature. To separate the effects of redistribution and net heat loss, we multiplied the change in overall heat balance by body weight and the specific heat of humans. The resulting change in mean body temperature was subtracted from the change in esophageal or tympanic membrane (core) temperatures, leaving the core hypothermia specifically resulting from redistribution. RESULTS Arm heat content decreased approximately 5 kcal/h after induction of anesthesia, but leg heat content increased markedly. Most of the increase in leg heat content was in the lower legs and feet. Core temperature increased slightly during the control period but decreased 0.8 +/- 0.3 degrees C in the 1st hour of anesthesia. Redistribution, contributing 89% to this initial decrease, required a net transfer of 20 kcal from the trunk to the extremities. During the subsequent 2 h of anesthesia, core temperature decreased an additional 0.4 +/- 0.3 degrees C, with redistribution contributing 62%. Thus, only 7 kcal were redistributed during the 2nd and 3rd hours of anesthesia. Redistribution therefore contributed 80% to the entire 1.2 +/- 0.3 degrees C decrease in core temperature during the 3 h of anesthesia. CONCLUSIONS Core hypothermia during the 1st hour after induction of epidural anesthesia resulted largely from redistribution of body heat from the core thermal compartment to the distal legs. Even after 3 h of anesthesia, redistribution remained the major cause of core hypothermia. Despite the greater fractional contribution of redistribution during epidural anesthesia, core temperature decreased only half as much as during general anesthesia because metabolic rate was maintained and the arms remained vasoconstricted.
TL;DR: Sevoflurane with nitrous oxide provides satisfactory anesthetic induction and intubating conditions; however, induction using sevoflURane without nitrousoxide is associated with a high incidence of patient excitement and prolonged time to intubation.
Abstract: BackgroundFor pediatric patients, sevoflurane may be an alternative to halothane, the anesthetic agent used most commonly for inhalational induction. The induction, maintenance, and emergence characteristics were studied in 120 unpremedicated children 1–12 yr of age randomly assigned to receive one
TL;DR: Prophylactic tranexamic acid, 10 mg-kg -1 followed by 1 mg- kg -1 -h -1 , decreases bleeding after extracorporeal circulation and larger doses do not provide additional hemostatic benefit.
Abstract: Background: Prophylactic administration of the autifibrinolytic drug tranexamic acid decreases bleeding and transfusions after cardiac operations. However, the best dose of tranexamic acid for this purpose remains unknown. This study explored the dose-response relationship of tranexamic acid for hemostatic efficacy after cardiac operation. Methods: In prospective, randomized, double-blinded fashion, 148 patients undergoing cardiac operation with extracorporeal circulation were divided into six groups: a placebo group and five groups receiving tranexamic -acid in loading doses before incision (range 2.5 to 40 mg-kg -1 ) and one-tenth the loading dose hourly for 12 h. The mass of blood collected by chest tubes over 12 h represented blood loss. Allogeneic transfusions within 12 h and within 5 d of surgery were tallied. Results: The six groups presented similar demographics. Patients receiving placebo had increased postoperative D-dimer concentration compared to groups receiving tranexamic acid. Patients receiving at least 10 mg-kg -1 tranexamic acid followed by 1 mg-kg -1 -h -1 bled significantly less (365, 344, and 369 g-12 h -1 , respectively, for those three groups) compared with patients who received placebo (552 g, P<0.05). Tranexamic dose did not affect transfusions. Only initial hematocrit affected whether a patient received an allogeneic transfusion within 5 days of operation (odds ratio 2.08 for each 3% absolute decrease in hematocrit). Conclusions: Prophylactic tranexamic acid, 10 mg-kg -1 followed by 1 mg-kg -1 -h -1 , decreases bleeding after extracorporeal circulation. Larger doses do not provide additional hemostatic benefit
TL;DR: It is indicated that skin and core temperatures contribute linearly to the control of vasoconstriction and shivering in men and that the cutaneous contributions average [nearly equal] 20% in both men and women.
Abstract: BackgroundThe contribution of mean skin temperature to the thresholds for sweating and active precapillary vasodilation has been evaluated in numerous human studies. In contrast, the contribution of skin temperature to the control of cold responses such as arteriovenous shunt vasoconstriction and sh
TL;DR: This study sought to determine which of the standard temperature monitoring sites best approximates brain temperature when deep hypothermia is rapidly induced and reversed during cardiopulmonary bypass.
Abstract: Background Brain temperature is closely approximated by most body temperature measurements under normal anesthetic conditions. However, when thermal autoregulation is overridden, large temperature gradients may prevail. This study sought to determine which of the standard temperature monitoring sites best approximates brain temperature when deep hypothermia is rapidly induced and reversed during cardiopulmonary bypass. Methods Twenty-seven patients underwent cardiopulmonary bypass and deep hypothermic circulatory arrest in order for each to have a giant cerebral aneurysm surgically clipped. Brain temperatures were measured directly with a thermocouple embedded in the cerebral cortex. Eight other body temperatures were monitored simultaneously with less invasive sensors at standard sites. Results Brain temperature decreased from 32.6 + 1.4 degrees Celsius (mean plus/minus SD) to 16.7 plus/minus 1.7 degrees Celsius in 28 plus/minus 7 min, for an average cerebral cooling rate of 0.59 + 0.15 degree Celsius/min. Circulatory arrest lasted 24 plus/minus 15 min and was followed by 63 + 17 min of rewarming at 0.31 plus/minus 0.09 degree Celsius/min. None of the monitored sites tracked cerebral temperature well throughout the entire hypothermic period. During rapid temperature change, nasopharyngeal, esophageal, and pulmonary artery temperatures corresponded to brain temperature with smaller mean differences than did those of the tympanic membrane, bladder, rectum, axilla, and sole of the foot. At circulatory arrest, nasopharyngeal, esophageal, and pulmonary artery mean temperatures were within 1 degree Celsius of brain temperature, even though individual patients frequently exhibited disparate values at those sites. Conclusions When profound hypothermia is rapidly induced and reversed, temperature measurements made at standard monitoring sites may not reflect cerebral temperature. Measurements from the nasopharynx, esophagus, and pulmonary artery tend to match brain temperature best but only with an array of data can one feel comfortable disregarding discordant readings.
TL;DR: One thousand fourteen patients receiving epidural fentanyl/bupivacaine infusions for analgesia after major surgery who were managed in the general surgical ward were prospectively surveyed.
Abstract: BackgroundEpidural fentanyl/bupivacaine infusions often are limited to high dependency units or intensive care units. One thousand fourteen patients receiving epidural fentanyl/bupivacaine infusions for analgesia after major surgery who were managed in the general surgical ward were prospectively su
TL;DR: It is concluded that t and ANOVA, without an accompanying arcsin transformation, are good tests to find differences in VAS measurements among groups.
Abstract: BackgroundA common type of study performed by anesthesiologists determines the effect of an intervention on pain reported by groups of patients. The goal of this study was to evaluate the effectiveness of t, analysis of variance (ANOVA), Mann-Whitney, and Kruskal-Wallis tests to compare visual analo
TL;DR: Computer simulations, using published times to discharge for drugs with «faster recovery,» such as propofol, showed that the use of these drugs would only decrease PACU costs if operating rooms were consistently scheduled to run later each day, which would greatly affect the number of PACU nurses needed.
Abstract: Background The goal of this study was to identify interventions that anesthesiologists can make to decrease total costs of a postanesthesia care unit (PACU). Methods Data were collected retrospectively from patients who underwent ambulatory surgery at our tertiary care center. Results Supplies and medications accounted for only 2% of PACU charges. Personnel costs, which depend on the peak number of patients in the PACU, accounted for almost all PACU costs. If nausea and vomiting could have been eliminated in each patient who suffered this complication, without causing sedation, the total time to discharge for all patients would have been decreased by less than 4.8% (95% confidence interval Conclusions Anesthesiologists have little control over PACU economics via choice of anesthetic drugs. The major determinant of PACU costs is the distribution of admissions.
TL;DR: Infusion of dexmedetomidine up to a targeted plasma concentration of 0.45 ng/ml appears to benefit perioperative hemodynamic management of surgical patients undergoing vascular surgery but required greater intraoperative pharmacologic intervention to support blood pressure and heart rate.
Abstract: BackgroundDexmedetomidine, a highly selective alpha2 -adrenergic agonist, increases perioperative hemodynamic stability in healthy patients but decreases blood pressure and heart rate. The goal of this study was to evaluate, in a preliminary manner, the hemodynamic effects of perioperatively adminis
TL;DR: The purpose of this study was to characterize the pharmacodynamic interaction between propofol and alfentanil for several clinically relevant end points.
Abstract: BackgroundPropofol and alfentanil are frequently combined to provide general anesthesia. The purpose of this study was to characterize the pharmacodynamic interaction between propofol and alfentanil for several clinically relevant end points.
TL;DR: The authors evaluated the hemodynamic effects of sevoflurane in healthy volunteers not undergoing surgery to establish an understanding of the detailed cardiovascular properties of an anesthetic.
Abstract: BackgroundSevoflurane is a new inhalational anesthetic with desirable clinical properties. In some clinical situations, an understanding of the detailed cardiovascular properties of an anesthetic is important, so the authors evaluated the hemodynamic effects of sevoflurane in healthy volunteers not
TL;DR: The results indicate that the intrinsic efficacy of opioid analgesics is inversely related to the degree of tolerance after continuous infusion, but that intrinsic efficacy does not significantly affect tolerance after once‐daily intermittent administration of these agents.
Abstract: BackgroundThe intrinsic efficacy of opioid analgesics has been suggested to play a role in the development of tolerance to these agents. However, the effect of differences in dosing protocol on tolerance to opioid analgesics of high or low efficacy has not been addressed. Therefore, the effect of op
TL;DR: Overall heat balance and distribution of heat within the body during the core-temperature plateau is evaluated, finding protection results from both vasoconstriction-induced decrease in cutaneous heat loss and altered distribution of body heat.
Abstract: BackgroundOnce triggered, intraoperative thermoregulatory vasoconstriction is remarkably effective in preventing further hypothermia. Protection results from both vasoconstriction-induced decrease in cutaneous heat loss and altered distribution of body heat. However, the independent contributions of
TL;DR: Premeditation with 2.5 micro gram/kg dexmedetomidine is effective in attenuating the cardiostimulatory and postanesthetic delirium effects of ketamine, but it increased the incidence of intra and postoperative bradycardia.
Abstract: BACKGROUND Dexmedetomidine is a new potent and highly selective alpha 2-adrenoceptor agonist with sedative-hypnotic and anesthetic sparing properties. Because of its sympathoinhibitory activity, it may prove useful in balancing the cardiostimulatory effects and attenuating the adverse central nervous system effects of ketamine. METHODS A double-blind, randomized and comparative parallel-group study design was employed in 40 volunteers with ASA physical status 1 who were scheduled for elective superficial surgery under ketamine anesthesia. Dexmedetomidine (2.5 micrograms/kg, n = 20) or midazolam (0.07 mg/kg, n = 20) was administered intramuscularly 45 min before induction of anesthesia. Anesthesia was induced with 2 mg/kg ketamine intravenously, and muscle relaxation was achieved with vecuronium. After tracheal intubation, anesthesia was maintained with nitrous oxide/oxygen (2:1) and additional 1 mg/kg intravenous ketamine boluses according to clinical and cardiovascular criteria. Hypotension and bradycardia were treated by increasing the intravenous infusion rate of crystalloids and intravenous atropine, respectively. Sedative and anxiolytic properties, intra- and postoperative drug requirements, psychomotor and cognitive impairments, and cardiovascular effects were compared between the two groups. RESULTS Dexmedetomidine and midazolam proved to have equal sedative and anxiolytic effects after intramuscular administration, but dexmedetomidine induced significantly less preoperative psychomotor impairment and less anterograde amnesia than did midazolam. Compared to midazolam, dexmedetomidine decreased the need for intraoperative ketamine and was more effective in reducing ketamine-induced adverse central nervous system effects. Dexmedetomidine also was superior to midazolam in attenuating the hemodynamic responses to intubation and the cardiostimulatory effects of ketamine in general, but it increased the incidence of intra- and postoperative bradycardia. CONCLUSIONS These results suggest that premedication with 2.5 micrograms/kg dexmedetomidine is effective in attenuating the cardiostimulatory and postanesthetic delirium effects of ketamine. However, because of its propensity to cause bradycardia, routine use of an anticholinergic drug should be considered.