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PubMed1995

[Halothane concentration inhaled by anesthesiologists during anesthesia through face masks].

Exposure to low concentrations of anesthetics is still an important medical concern. We measured halothane concentrations in air inspired by anesthesiologists practicing inhalational anesthesia through face masks (10 cases, 200 sampling points). Halothane concentrations were 0 to 15 ppm (mean 4.89 ppm), higher than the safety level recommended by National Institute for Occupational Safety and Health (NISOH). However, these concentrations were clearly low in a room air-conditioned with vertical laminar flow providing total air exchange rate of 30 per hour (0.55 +/- 0.53 ppm, n = 40) compared to those in the rooms with horizontal laminar flow of 25 (5.98 +/- 3.80 ppm, n = 80, P < 0.001). These observations indicate the importance of ventilation systems of operating rooms for avoiding anesthetic gas exposure to anesthesiologists during inhalational anesthesia through face masks.

Anesthesia, Inhalation↗
PubMed2006

[Sevoflurane-N2O inhalation anaesthesia with laryngeal mask airway and propofol-ketamine intravenous anaesthesia in strabismus surgery].

OBJECTIVE: To investigate the advantages and disadvantages of sevoflurane-N2O inhalation anesthesia with laryngeal mask airway (LMA) and propofolketamine total intravenous anaesthesia in children undertaking strabismus surgery. METHODS: Eighty children undertaking strabismus surgery were randomly divided into sevoflurane-N2O inhalation anaesthesia group with LMA (volatile group, n=40) and propofol-ketamine total intravenous anesthesia group (TIVA group, n=40). LMA was used to secure respiratory airway in the volatile group, but LMA or endotracheal intubation was not used in the TIVA group. All children breathed spontaneously during operative period. The anesthesia was maintained with 2%-3% sevoflurane-50% N2O-50% O2 in the volatile group, and continuous intravenous infusion with propofol 5-10 mg/(kg x h) plus ketamine 1-2 mg/(kg x h) in the TIVA group. The incidence of SpO2 less than 95% and the movement of the limbs and head induced by operative stimulation, oculocardiac reflex (OCR) and postoperative vomiting (POV) were recorded in all children. RESULTS: The incidence of limbs and head movement, the incidence of SpO2 less than 95% and OCR were significantly lower in the volatile group than those in the TIVA group (P < 0.01); but the incidence of POV was significantly higher in the volatile group than that in the TIVA group (P < 0.01). CONCLUSION: Sevoflurane-N2O-O2 anesthesia with LMA can secure respiratory airway of patients, avoid hypoxemia, and have good anesthetic quality and low OCR incidence. It is a new anesthesia method with more advantages in children undertaking strabismus surgery, but the prevention and treatment of POV must be noticed.

Anesthesia, Intravenous↗
PubMed1984

Liver circulation and function during isoflurane and halothane anesthesia.

Hepatic arterial blood flow (HABF) and portal blood flow (PBF) were measured in 18 dogs while awake and during isoflurane and halothane anesthesia. Surgical preparation 1 week before the measurements consisted of a left thoracotomy, placement of a left atrial catheter, and insertion of another catheter into the distal aorta via the left femoral artery. Cardiac output and liver blood flow were determined using microspheres at three stages: stage 1-awake state; stage 2-after 45 min of 1 MAC of isoflurane (eight dogs) or halothane (10 dogs) anesthesia; and stage 3-after 45 min of 2 MAC of inhalation anesthesia. Half-life and fractional clearance for indocyanine green (ICG) were determined 1 day before the experiment (awake state), and at the end of stages 2 and 3. Mean arterial pressure (MAP) and cardiac index (CI), as well as PBF, decreased during isoflurane and halothane anesthesia. HABF increased significantly during isoflurane anesthesia, remained unchanged during 1 MAC of halothane anesthesia, and significantly decreased during 2 MAC of halothane anesthesia. Apparently, hepatic oxygen supply was maintained much better during isoflurane than during halothane anesthesia. PBF correlated with CI during halothane (r = 0.97) and, to a certain extent, with MAP during isoflurane (r = 0.66). HABF correlated with CI and MAP during halothane (r = 0.74 and 0.71, respectively) but did not correlate with systemic hemodynamic variables during isoflurane. ICG half-life significantly increased during 1 and 2 MAC of halothane anesthesia. The degree of increase did not correlate with the level of anesthesia or the decrease in total hepatic blood flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2006

[Intraoperative monitoring of visual evoked potentials].

Our success rate of intraoperative monitoring of visual evoked potential (VEP) had been approximately 30% in the past. In order to improve recording rate of intraoperative VEP, we developed a new stimulating device using high power light emitting diodes. Electroretinogram was simultaneously recorded to understand whether flash stimulation reached the retina. In addition, total venous anesthesia with propofol was used to avoid the adverse effect of inhalation anesthesia. We report the results after introduction of these improvements. Intraoperative monitoring of VEP was attempted in 35 cases. We evaluated success rate of VEP recording, correlation between VEP findings and postoperative visual function, and reasons why recording was not successful. Stable and reproducible waveforms were obtained in 59 sides (84%). Two cases, whose VEP deteriorated intraoperatively, developed postoperative visual disturbance: In 11 sides (16%), stable waveforms were not obtained. There were two main causes. In 8 sides out of 11, the cause was attributed to pre-existing severe visual disturbance. In these 8 sides, VEP in the awake state was not recordable or was recordable, but with very low amplitudes under 1 microV. In the other 3 sides, the cause was attributed to movement of a stimulating device by reflecting the fronto-temporal scalp flap. In conclusion, the successful recording rate was increased to 84% from approximately 30%, after introduction of various trials. We need further improvement in recording intraoperative VEP to establish a reliable intraoperative monitoring method for VEP.

Aged↗
PubMedDate not supplied

[Myringotomy under topical anesthesia with phenol].

Myringotomy is a common outpatient surgical procedure. It can be performed under general inhaled anesthesia, but it is usually carried out under local anesthesia by lidocaine infiltration or instillation of different anesthetic agents. We present our experience with myringotomy and tympanic tube placement using topical anesthesia with 88% phenol as an outpatient procedure. We report 55 patients in which we performed 81 treatments. In this series, only two ears (2.47%) did not tolerate the surgical procedure, tube insertion under general anesthesia being necessary in one case. Topical anesthesia with phenol facilitates the outpatient treatment of adult otitis media with effusion.

Adolescent↗
PubMed1995

A system model for halothane closed-circuit anesthesia. Structure considerations and performance evaluation.

BACKGROUND: Previously, the authors described a physiologic model for closed-circuit inhalational anesthesia. The basic version of this system model was clinically validated for isoflurane. An extended version adopted nonpulmonary elimination causing a constant fraction of anesthetic to be irreversibly lost. This version improved the accuracy of the model for enflurane. The model's performance for other inhalational anesthetics that are not biochemically inert, such as halothane, remained to be evaluated. METHODS: The current study quantified the predictive performance of four versions of the model by comparison of the predicted and measured alveolar halothane concentration-time profiles in 53 patients. Version A did not incorporate nonpulmonary elimination, whereas version D adopted a nonlinear hepatic nonpulmonary elimination following Michaelis-Menten kinetics. A and D used fixed partition coefficients. Their counterparts, A' and D', were formulated to examine the impact of age-adjusted partition coefficients on the accuracy of our model. Each concentration measured by mass spectrometry was compared to four predicted concentrations calculated by four computer simulations (one per version). For each patient, the authors calculated the root mean squared error (rmse; typical error size), bias (systematic component), and scatter of the prediction errors. RESULTS: Fifty-three patients were anesthetized with 330 ml of liquid halothane via 426 bolus injections during more than 61 h; 21,890 alveolar concentrations (average 0.6 vol%) were measured. Version D' showed the best overall performance with an rmse of 19.6 +/- 7.2%, a bias of 0.5 +/- 15.9%, and a scatter of 13.2 +/- 3.5% (mean +/- SD). CONCLUSIONS: The model incorporating nonpulmonary elimination and age-adjusted partition coefficients (D') is sufficiently reliable and accurate to represent halothane closed-circuit anesthesia. This system model, with its various versions, is a valuable tool to predict the dynamics of isoflurane, enflurane, and halothane for clinical, educational, and research purposes.

Adult↗
PubMed2005

[The consumption of nitrous oxide used for general anesthesia has been markedly reduced in recent years in our institute].

We reported the incidence of general anesthesia using nitrous oxide (N2O), one of the greenhouse gases in the atmosphere, and the total consumption of N2O in our institute in 1990, 1995, 2000, and 2004. Nitrous oxide was used in 93%, 97%, 89%, and 49% of general anesthesia in 1990, 1995, 2000, and 2004, respectively. The consumption of N2O was markedly reduced from 1314 kl in 1990 to 413 kl in 2004. In 1996, propofol was introduced for total intravenous anesthesia. Moreover, low flow anesthesia (total gas flow not exceeding 2 l x min(-1)) was vigorously introduced. We consequently decreased the amount of N2O consumed during inhalational anesthesia despite the increase in cases of general anesthesia in recent years.

Air Pollutants↗
PubMed2005

Comparison of the cardiopulmonary effects of anesthesia maintained by continuous infusion of ketamine and propofol with anesthesia maintained by inhalation of sevoflurane in goats undergoing magnetic resonance imaging.

OBJECTIVE: To compare the cardiopulmonary effects of anesthesia maintained by continuous infusion of ketamine and propofol with anesthesia maintained by inhalation of sevoflurane in goats undergoing magnetic resonance imaging. ANIMALS: 8 Saanen goats. PROCEDURES: Goats were anesthetized twice (1-month interval) following sedation with midazolam (0.4 mg/kg, IV). Anesthesia was induced via IV administration of ketamine (3 mg/kg) and propofol (1 mg/kg) and maintained with an IV infusion of ketamine (0.03 mg/kg/min) and propofol (0.3 mg/kg/min) and 100% inspired oxygen (K-P treatment) or induced via IV administration of propofol (4 mg/kg) and maintained via inhalation of sevoflurane in oxygen (end-expired concentration, 2.3%; 1X minimum alveolar concentration; SEVO treatment). Cardiopulmonary and blood gas variables were assessed at intervals after induction of anesthesia. RESULTS: Mean +/- SD end-expired sevoflurane was 2.24 +/- 0.2%; ketamine and propofol were infused at rates of 0.03 +/- 0.002 mg/kg/min and 0.29 +/- 0.02 mg/kg/min, respectively. Overall, administration of ketamine and propofol for total IV anesthesia was associated with a degree of immobility and effects on cardiopulmonary parameters that were comparable to those associated with anesthesia maintained by inhalation of sevoflurane. Compared with the K-P treatment group, mean and diastolic blood pressure values in the SEVO treatment group were significantly lower at most or all time points after induction of anesthesia. After both treatments, recovery from anesthesia was good or excellent. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that ketamine-propofol total IV anesthesia in goats breathing 100% oxygen is practical and safe for performance of magnetic resonance imaging procedures.

Analysis of Variance↗
PubMed1995

The perioperative nurse's role in anesthesia management.

The perioperative nurse's role in anesthesia management of the surgical patient begins with a preoperative patient assessment and ends when the patient recovers from the effects of anesthesia. An understanding of the following concepts enhances the perioperative nurse's ability to collaborate with anesthesia care providers in providing optimal care: anesthesia risk classifications, choice of anesthetic agents, importance of patient positioning, anesthesia induction and intubation techniques, levels of general anesthesia, inhalational agents, malignant hyperthermia, and patient monitoring parameters during local and regional anesthesia.

Anesthesia↗
PubMed1999

A comparison of the analgesic efficacy of 0.25% levobupivacaine combined with 0.005% morphine, 0.25% levobupivacaine alone, or 0.005% morphine alone for the management of postoperative pain in patients undergoing major abdominal surgery.

UNLABELLED: We compared the relative efficacy of the combination of the single-isomer local anesthetic levobupivacaine and the opioid analgesic morphine versus both drugs alone for postoperative epidural analgesia after major abdominal surgical procedures. Thoracic epidural anesthesia was produced and maintained with levobupivacaine 0.75% in combination with general inhaled anesthesia without opioids. Patients were randomized to one of three postoperative treatment groups: 1) a combination of levobupivacaine 0.25% and morphine 0.005%; 2) levobupivacaine 0.25%; or 3) morphine 0.005%. Postoperatively, all epidural infusions were commenced at a rate of 4 mL/h. Patients could receive a 4 mL-bolus dose and an increase in the epidural infusion rate by 2 mL/h on request for supplemental analgesia. Patients were also allowed ketorolac as a supplemental analgesic at any time after the first analgesic request. Patients in the combination group had longer times to request for supplemental analgesia as compared with the levobupivacaine only group (P < 0.05) and a trend toward longer time to request as compared with the morphine only group (P = 0.066). Patients in the combination group had lower visual analog scale pain scores at rest and activity at 4 and 8 h and fewer requests for supplemental ketorolac (P < 0.05). In conclusion, this study demonstrates a significant improvement in postoperative analgesic efficacy with the combination of levobupivacaine and morphine for continuous epidural analgesia after major abdominal surgical procedures. IMPLICATIONS: A significant improvement in postoperative analgesic efficacy is demonstrated with the thoracic epidural administration of the combination of the single-isomer local anesthetic levobupivacaine 0.25% and morphine 0.005% in patients after major abdominal surgical procedures as compared with either drug used alone.

Abdomen↗
PubMed2005

Intravenous or inhaled induction of anesthesia in adults? An audit of preoperative patient preferences.

If given a choice, would patients prefer an inhaled or IV method of inducing anesthesia? We investigated the choice between inhaled and IV induction of anesthesia of adult patients presenting to an academic institution for ambulatory surgery. Of 240 patients audited at the preoperative visit, 212 (88%) reported anesthetic histories in which anesthesia had been induced IV and by inhalation in 203 (96%) and 5 (2%) patients, respectively, with the remaining 4 (2%) having no recall of route of the induction of anesthesia. Seventy-eight (33%) patients selected IV induction, 120 (50%) chose inhaled induction, and 42 (17%) patients were undecided. Sevoflurane was used successfully for induction in 154 patients to whom it was offered. These findings seem to contradict the concept that most adult patients have an aversion to anesthesia masks and suggest that a fear of needle stick may be more prevalent among some populations of American adults. Where manpower and facilities permit and in the absence of risk of regurgitation or airway difficulty, it is suggested that enquiry be made of healthy adults presenting for elective ambulatory surgery as to their preferred route for the induction of anesthesia.

Adolescent↗
PubMed2001

The effect of brief halothane anesthesia during daily gavage on complications and body weight in rats.

We examined retrospectively the effects of brief halothane anesthesia during daily gavage administration of vehicle on gavage-related complications and body weight in ovariectomized female Wistar rats. The number of gavage-related deaths or animals requiring euthanasia due to gavage problems was dramatically reduced, but the occurrence of incomplete vehicle retention during gavage was increased appreciably in halothane-anesthetized animals. Halothane-anesthetized rats maintained daily body weight for a longer period than did awake animals. Our observations suggest that the use of brief inhalational anesthesia reduces gavage-associated death and euthanasia due to esophageal trauma and minimizes stress-related weight loss.

Anesthesia↗
PubMed2000

Neonatal halothane anesthesia affects cortical morphology.

Neonatal cryoanesthesia has recently been documented to affect morphology and behavior after a single exposure [Dev. Brain Res. 111 (1998) 89; Horm. Behav. 37 (2000) 169]. In the current experiment, we investigated the effect of one-time exposure to halothane inhalant anesthesia on neonatal rats of both sexes. Fifteen minutes of exposure on postnatal day one resulted in detectable changes in the volume of the visual cortex at 3 months. Thus, neonatal halothane alters neural development and its effects are observable in the adult rat.

Anesthesia↗
PubMed1996

The effects of sevoflurane, isoflurane, halothane, and enflurane on hemodynamic responses during an inhaled induction of anesthesia via a mask in humans.

A rapid increase in isoflurane or desflurane concentration induces tachycardia and hypertension and increases-plasma catecholamine concentration. Little information is available as to whether sevoflurane, halothane, and enflurane induce similar responses during anesthesia induction via mask. Fifty ASA physical status I patients, aged 20-40 yr, and scheduled for elective minor surgery, received one of four volatile anesthetics: sevoflurane, isoflurane, halothane, or enflurane. Anesthesia was induced with thiamylal, followed by inhalation of 0.9 minimum alveolar anesthetic concentration (MAC) of the anesthetic in 100% oxygen via mask. The inspired concentration of anesthetic was increased by 0.9 MAC every 5 min to a maximum of 2.7 MAC. Heart rate (HR) and systolic blood pressure (SBP) were measured before and every minute for 15 min during anesthetic inhalation. In the sevoflurane and isoflurane groups, venous blood samples were drawn to determine the concentrations of plasma epinephrine and norepinephrine 3 min after each increase in anesthetic concentration. Sustained increments in HR were observed after increases in inspired isoflurane concentration to 1.8 MAC and 2.7 MAC (peak changes of 15 +/- 3 and 17 +/- 3 bpm, respectively). Isoflurane also increased SBP transiently after the inspired concentration was increased to 2.7 MAC (peak change of 10 +/- 4 mm Hg). Enflurane increased HR after the inspired concentration was increased to 2.7 MAC (peak change of 9 +/- 2 bpm). In contrast, changes in sevoflurane and halothane concentrations did not induce hyperdynamic responses. Plasma norepinephrine concentration in the isoflurane group was significantly higher than that in the sevoflurane group during 2.7 MAC (P = 0.022). We propose that there is a direct relationship between airway irritation of the anesthetic and immediate cardiovascular change during an inhaled induction of anesthesia.

Adult↗
PubMed1951

An evaluation of cesarean section.

The risks of cesarean section have been reduced in step with the increase in safety of all major surgical procedures. In a series of 13,153 deliveries, 1,265 (9.6 per cent) were by cesarean section. There were three obstetrical maternal deaths in 11,888 cases in which delivery was by the vaginal route-0.025 per cent. In the series of 1,265 deliveries by cesarean section there was one death attributable to the operation-0.08 per cent. The total uncorrected fetal loss following cesarean section was 3.8 per cent. This compares favorably with fetal loss of 3.2 per cent in the vaginal delivery group in this series, and with fetal loss rates reported from large obstetrical centers. Anesthesia by spinal injection is the method of choice in cesarean section. There were no maternal deaths or accidents attributable to spinal anesthetic, and in no case was it felt that fetal death was attributable to it. The incidence of maternal morbidity in the cesarean section group following spinal anesthesia was 15.8 per cent-less than half the incidence of morbidity following inhalation anesthesia.

Anesthesia, Spinal↗
PubMed1989

Differing effect of agonist and antagonist muscle relaxants on cat jaw muscles.

Mouth closure and an increased resistance to mouth opening follow succinylcholine administration in humans. To elucidate the effects of succinylcholine on masticatory muscle function, mouth opening in the cat, produced by a constant test force, was measured during steady state halothane anesthesia. After baseline measurements, either succinylcholine (0.3 mg.kg-1 of body weight) or vecuronium (0.1 mg.kg-1 of body weight) was infused intravenously, and mouth opening measurements were repeated for up to 30 min. Concomitantly, muscle relaxant effect was quantified by measurement of the neurally-evoked tibialis anterior muscle response. All animals given succinylcholine displayed active jaw closure, which was followed by an increased resistance to mouth opening. This increased resistance was present after cessation of fasciculations and during complete twitch suppression. It lasted beyond the time at which the limb muscle twitch had fully recovered. Vecuronium administration was associated with a decreased resistance to mouth opening without a closing action. The initial jaw closure and the subsequently increased resistance to mouth opening after succinylcholine administration during halothane anesthesia in the cat are comparable with mouth opening changes after succinylcholine administration during inhalation anesthesia in humans. The cat may serve as an animal model for study of the mechanisms involved in responses of jaw muscles to succinylcholine with use of techniques inappropriate in humans.

Animals↗