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[Comparison of requirement for postoperative analgesics after inhalation and total intravenous anesthesia].

BACKGROUND: We evaluated the requirement for postoperative analgesics in 88 patients undergoing abdominal total hysterectomy with inhalation anesthesia or with total intravenous anesthesia. METHODS: Anesthesia was induced in the inhalation anesthesia (GOS, n = 52) group with propofol and fentanyl, and maintained with sevoflurane, nitrous oxide balanced with oxygen, and additional administrations of fentanyl up to 0.2 mg in total. The patients in the total intravenous anesthesia (TIVA, n = 36) group were managed with target controlled infusion for propofol and intermittent administration of fentanyl. Effect site concentrations of fentanyl at the end of surgery were calculated using a pharmacokinetic-pharmacodynamic model. We divided the postoperative time course and evaluated the types, dosages, and prescription times of postoperative analgesics in each. RESULTS: Both total dosage and effect-site concentration of fentanyl were higher in the TIVA group than in the GOS group, and total prescription time in the TIVA group was significantly less during the 24 hrs after the operation. Supplemental prescription intervals of buprenorphine were significantly less in the TIVA group. Since administration of fentanyl during operation was adequate, patients in the TIVA group were considered to be in a sufficient analgesic state at the end of operation. CONCLUSIONS: The postoperative pain can be reduced with TIVA.

Adult↗

Prolonged hyporesponsiveness of airway smooth muscle to histamine following general anesthesia.

The prolonged effect of barbiturates and inhalation anesthesia on airway response to histamine was studied in five groups of dogs. Group B (n = 10), H24 (n = 5), and H72 (n = 5) were anesthetized with sodium thiamylal (B) or halothane and N2O (H24, H72) for 3 h, during which a dose-response curve to histamine was obtained. The animals were then allowed to recover; 24 h (B and H24) or 72 h later, the animals were killed and an in vitro dose-response curve to histamine was obtained on a tracheal smooth muscle (TSM) specimen. Group C (n = 5), the control group, had no prolonged exposure to anesthesia. The dogs were immediately killed and the in vitro histamine response of the TSM was measured. The results (mean +/- SE) showed that the smooth muscle contractile properties (i.e., the maximum contraction to electrical field stimulation) were comparable in all four groups: 111 +/- 12 g (B); 168 +/- 23 g (H24); 106 +/- 32 g (H72); and 107 +/- 31 g (C). The maximum response (mean +/- SE) to histamine (as % of maximum electrical contraction) was: 15 +/- 6% (B), 30 +/- 9% (H24), 32 +/- 12% (H72), and 50 +/- 8% (C). Statistical analysis of the data showed that the histamine response of Group B and Group H24 was significantly decreased compared to Group C (P less than 0.01 and less than 0.05, respectively); in Group H72 the results were not significantly different from Group C (0.1 greater than P greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, General↗

A case of difficult airway due to lingual tonsillar hypertrophy in a patient with Down's syndrome.

In this report, we describe airway management of symptomatic lingual tonsillar hypertrophy in a pediatric patient with Down's syndrome. Besides obstructive sleep apnea, the history included a small atrial septal defect with mild aortic regurgitation and Moyamoya disease. Anesthesia was induced with IV administration of 1 mg/kg of propofol, followed by inhalation of sevoflurane in 100% oxygen. Muscle relaxants were not used on induction. Rigid laryngoscopy could not visualize the epiglottis because of hypertrophied tonsillar tissue, and mask ventilation became difficult when spontaneous breathing stopped. We avoided using a laryngeal mask airway because of a slight bleeding tendency presumably caused by preoperative antiplatelet therapy. Fiberoptic bronchoscopy through the nasal cavity in combination with jet ventilation successfully identified the glottis and allowed nasotracheal intubation to be accomplished. After lingual tonsillectomy, the patient was extubated on the seventh postoperative day, after supraglottic edema had resolved. Fiberoptic nasotracheal intubation under inhaled anesthesia may therefore be preferable in pediatric or uncooperative patients with symptomatic lingual tonsillar hypertrophy.

Anesthesia, General↗

Comparison of anesthetic techniques in patients undergoing heart valve replacement.

A prospective study of 324 adult patients undergoing operations requiring cardiopulmonary bypass for heart valve replacement was undertaken to determine the effect of anesthetic technique on outcome. Patients received one of three primary techniques: fentanyl (40-100 micrograms/kg), sufentanil (4-8 micrograms/kg), or diazepam (0.4-1 mg/kg) with ketamine (3-6 mg/kg). Supplemental inhalation anesthesia with enflurane, halothane, or isoflurane was used in 43.8% of cases. Patients in these anesthetic groupings had similar perioperative demographic and risk classifications. Although there were differences in the requirements for vasopressors postoperatively among the intravenous anesthetic agents, neither mortality rates, length of ICU stay, nor incidence of postoperative heart failure showed the advantage of any intravenous or inhalational agent. There were also no significant differences in the incidences of serious pulmonary, renal, or neurologic morbidity among primary anesthetic techniques nor among supplemental inhalation agents. Multivariate discriminant analysis of these data suggests that many factors are significantly more important than anesthetic technique as determinants of outcome after heart valve replacement.

Analysis of Variance↗

[Is measuring the depth of anesthesia sensible? An overview on the currently available monitoring systems].

Without any doubt there is an increasing need for accurately measuring depth of anesthesia - from the viewpoint of the anesthesiologist and also of the patient. The ideal monitoring should fulfill the following criteria: It should be applicable for any type of anesthesia (intravenous as well as inhalative anesthesia); the monitor must have an extremely high sensitivity (each patient being awake must be recognized by the device).If the monitor does not have a high sensitivity, the monitor itself might lead to an increasing number of patients being awake during anaesthesia, because the anesthesiologist might rely on the monitor and does not deepen anesthesia while the patient is awake. Specificity is not as important as sensitivity. As incidence of interoperative awareness is low, one must monitor more than 750 patients to recognize only one patient who is awake. Finally, the monitoring device must be economic. If costs are considerably increased by measuring depth of anesthesia in today's climate of cost consciousness, the monitoring has to be restricted to special high risk groups of patients. If monitoring depth of anesthesia will become simple, safe, and economic, each anesthesia should be monitored for its depth, as today each patient needs pulseoxymetry. We try to give an orientation about the available devices for monitoring depth of anesthesia. Since the introduction of BIS interest in measuring depth of anesthesia is growing very dynamically. Due to the dynamic growth we hope that we were able to present an actual and complete overview about the monitoring systems for measuring depth of anesthesia. Until today no monitoring system has proven to fulfill the mentioned criteria. Monitoring of the depth of anesthesia will be based on any processing of the spontaneous EEG or its evoked potentials. Which type of monitoring, entropy, BIS, PSI, or MLAEP will be used in clinical routine will be shown in the future. All available monitors are no predictors, whether depth of anesthesia is sufficient for the next painful surgical stimulus. They can only monitor the anesthetic state at the time of measurement. There is no "golden number" predicting absolutely safely that the patient is in adequate anesthesia. The anesthetist must consider any technique for monitoring of the depth of anesthesia as an additional help in improving care for his patient.

Anesthesia, General↗

Cholera toxin as a mucosal adjuvant for respiratory antibody responses in mice.

Cholera toxin was investigated as an adjuvant for anti-virus antibody responses in the respiratory mucosa of mice. Two methods of applying cholera toxin were evaluated: oral administration and intranasal administration. Oral immunization with Sendai virus in the presence of cholera toxin effectively primed for respiratory anti-viral antibody responses, whereas oral immunization with Sendai virus alone was ineffective in this respect. In nasal washes, IgA was the predominant anti-viral antibody enhanced by oral cholera toxin; in bronchoalveolar washes, the enhanced anti-viral antibodies included IgG, IgA, and IgM. Effects of direct administration of cholera toxin to the respiratory mucosa on respiratory anti-viral antibody responses depended on the method of anesthesia used during immunization. With inhalation anesthesia (ether), cholera toxin had no adjuvant effect on respiratory antibody responses to coadministered Sendai virus. In contrast, under parenteral anesthesia (i.e., intraperitoneal ketamine), mice which received cholera toxin and Sendai virus via the respiratory tract showed significantly higher anti-viral IgA and IgG antibody titers in nasal washes and IgG antibody in bronchoalveolar washes than mice which received the virus only.

Adjuvants, Immunologic↗

[Propofol in general anesthesia in children].

For a long period of time propofol has been in use for total intravenous anesthesia in adults. In our literature there are no data on the use of propofol in pediatric anesthesia. The aim of the study was to compare effects of propofol for the induction of anesthesia, maintenance and recovery after anesthesia, with barbiturate, that is, inhalation anesthesia during spontaneous breathing. 50 children underwent propofol anesthesia. A control group comprised 50 children who underwent thiopentone and halothane anesthesia. The average propofol dose was 2.38 mg/kg/tt. Monitoring of cardiovascular parameters revealed statistically significant variations in systolic and diastolic pressure in both groups, but a more significant decrease was recorded in the propofol group. The decrease, recorded only during the initiation of anesthesia, stabilized afterwards. Side effects (pain during the initiation, apnea, spontaneous movements) were present in the propofol anesthesia, while in the halothane group they were reduced. In the propofol group period of recovery was short, indicating advantages of this anesthetic in day care centers.

Adolescent↗

[Anesthesia for funnel chest operation].

The incidence of perioperative complication and days of hospital stay were studied in 56 patients with funnel chest operation under inhalational anesthesia (18 cases), intravenous anesthesia (23 cases) and epidural anesthesia (15 cases). Perioperative complication occurred most frequently in the inhalational group and was followed by intravenous and epidural group. Postoperative hospitalization on an average was 21.4 days in the inhalational group, 21.9 days in the intravenous group and 16.7 days in the epidural group. It is said that postoperative pain leads to splinting of the chest, which can cause atelectasis and/or pneumonia. Severe postoperative pulmonary complication was reduced in the epidural groups. As a result, hospitalization in the epidural group was shorter than in other groups. This study suggests that epidural anesthesia is more advantageous for funnel chest operation because epidural anesthesia has protective action against arrhythmia and postoperative pulmonary complication.

Adolescent↗

[Continuous thoracic epidural blockade in combination with general anesthesia with nitrous oxide, oxygen, and sevoflurane in two patients with myasthenia gravis].

Continuous thoracic epidural anesthesia (T4/5) using 4-5 ml.h-1 of 1.5% lidocaine with 1:200,000 epinephrine and inhaled anesthesia using nitrous oxide, oxygen and sevoflurane were performed in two patients, (40 and 22 yr-old females) with myasthenia gravis. This combined anesthetic technique provided muscle relaxation for endotracheal intubation and optimal operating conditions, including muscle relaxation and stability of hemodynamics during transsternal thymectomy. Further, continuous epidural anesthesia using 4 ml.h-1 of 0.25% bupivacaine provided postoperative pain relief without other analgesics and stable postoperative respiratory conditions. In conclusion, we confirm the benefits of this technique which provides not only safe and stable conditions during the surgery, but also an improved comfort for patients in the postoperative period following transsternal thymectomy for myasthenia gravis.

Adult↗

[The effect of low-rose prostaglandin E1 on circulation, respiration and body temperature during surgical anesthesia].

We investigated the effects of low-dose prostaglandin E1 (PGE1) on circulation, respiration, and body temperature during surgical anesthesia. We studied 109 adult patients undergoing upper abdominal operations under thoracic epidural combined with inhalational anesthesia. Patients were divided into 2 groups; Control group (n = 42) and PGE1 group (n = 67). In PGE1 group, PGE1 infusion was started at the rate of 0.02 microgram.kg-1.min-1 before the induction of anesthesia and was terminated at the end of surgery. There were no differences between the groups in demographic, anesthetic and surgical characteristics. After treatment with PGE1, arterial pressure decreased slightly but significantly, resulting in lower arterial pressure in PGE1 group than in control group before the induction of anesthesia. After the induction of anesthesia, however, arterial pressure decreased significantly in both groups, and the differences in arterial pressure between the groups were not observed any more during surgery. Heart rate was not different between the groups throughout the study period. Intraoperative urine output was greater in PGE1 group than in control group. PaO2/FIO2 ratio was not different between the groups both before and during anesthesia. Rectal temperature remained slightly but significantly lower in PGE1 group throughout surgery. Rectal-to-palm temperature gradient tended to be smaller in PGE1 group 1 hour after the induction of anesthesia. Low-dose PGE1 reduced arterial pressure. However, the difference in arterial pressure between the groups was so small that the difference disappeared during surgery. Meanwhile, low-dose PGE1 increased urine output, suggesting that renal blood flow was better-maintained with PGE1. In spite of several investigations reporting an unfavorable effect of PGE1 on PaO2, low dose PGE1 did not affect PaO2 in this study. Finally low-dose PGE1 reduced core temperature, though slightly, probably through redistribution of the body heat.

Adult↗

An anesthesia mask gas-scavenging system.

The level of N2O contamination in the breathing zone of anesthesiologists was measured while they administered inhalation anesthesia by mask to five patients. A mask gas-scavenging attachment was used for 30 minutes and then removed while anesthesia continued for a further 30 minutes. The levels of N2O with and without the scavenging attachment were compared. Using the scavenging attachment, N2O contamination was reduced from greater than 150 ppm to less than 5 ppm, a level well below the 25 ppm limit recommended by the National Institute for Occupational Safety and Health. The scavenging device is a simple and effective way to reduce operating room contamination with N2O during delivery of anesthesia by mask.

Adult↗

Portable anesthesia transport system.

Medical procedures that require general anesthesia outside of the traditional operating room setting have become commonplace. This paper describes a portable inhalational anesthesia machine developed for use in these outlying areas within the hospital. The device combines the basic components of vaporizer, oxygen analyzer, oxygen flow-meter, disposable carbon dioxide absorber and oxygen flush valve into a small package that may be carried with one hand. The unit may be used as a tabletop anesthesia machine or may be attached to a patient transport bed by means of a dedicated stand.

Anesthesia, Inhalation↗

Anesthetic and postanesthetic management of sea turtles.

OBJECTIVE: To examine the physiologic effects of inhalation anesthesia in aquatic turtles to improve anesthetic techniques and postanesthetic monitoring. DESIGN: Retrospective case series. ANIMALS: 9 Kemp's ridley sea turtles. PROCEDURE: Isoflurane was used as the general anesthetic during 14 minor surgical procedures. Turtles were orotracheally intubated, and a surgical plane of anesthesia was maintained with 2.7 +/- 0.4% (mean +/- SE) isoflurane. The duration of anesthesia was 131 +/- 12 minutes. Pulse rate, blood pressure, blood gases (PaO2 and PaCO2) and pH, blood lactic acid concentration, and capnography were used to evaluate the physiologic responses of sea turtles to isoflurane. RESULTS: An isoflurane concentration of 3.4 +/- 0.3% provided anesthetic induction in 7 +/- 1 minutes. The mean duration of the recovery phase was 241 +/- 31 minutes. The duration of the recovery phase was not affected by the duration of anesthesia, type of carrier gas, method of ventilatory weaning, or use of selected pharmacologic agents. The recovery phase was characterized by hypoxemia, progressive acidemia, hypercapnia, and lactic acidosis. Awakening in the turtles was preceded by a characteristic tachycardia and tachypnea. All sea turtles recovered from isoflurane anesthesia without apparent adverse effects within 24 hours. CLINICAL IMPLICATIONS: Isoflurane appears to be safe and effective in providing surgical anesthesia in turtles that require a timely return to an aquatic environment. This study should assist veterinarians in predicting the physiologic responses of aquatic turtles to inhalation agents.

Anesthesia, Inhalation↗

PaCO2 for optimum washout of inhalational anesthetics from the brain. A model study.

A hypothesis was established that, during emergence of inhalational anesthesia, hyperventilation and accompanying hypocapnia beyond a certain limit may actually disturb rather than enhance the washout of inhalational anesthetics from the brain because of a decreased cerebral blood flow. Two mathematical models were constructed and the washout of nitrous oxide, halothane and methoxyflurane were studied. In model I, the whole body consisted of a single compartment, and blood flow to this compartment was assumed to change proprotionally with the PaCO2. In model 2, the body was divided into two compartments, brain and the rest of the body. It was assumed that the blood flow to the brain compartment varies proportionally with the PaCO2, while that to the rest of the body remains constant. The analysis indicated that there indeed existed the PaCO2 values at which the washout of anesthetics from the brain can be maximally achieved. In model 1, they were 49.0, 22.1 and 9.7 mmHg for nitrous oxide, halothane, and methoxyflurane, respectively. In model 2, these PaCO2 values varied with time. While the hypothesis was proven to be valid, we conclude that it is of limited clinical significance. For halothane and methoxyflurane, these theoretically optimum PaCO2 values are sufficiently low. For nitrous oxide, the variation of PaCO2 makes little difference clinically, because its washout is fast enough regardless of PaCO2.

Anesthesia, Inhalation↗

Occupational exposure to inhalational anesthetics during cardiac surgery on cardiopulmonary bypass.

BACKGROUND: Eventual hazards from occupational exposure of operating room personnel to inhalational anesthetic agents cannot yet be definitively excluded. We determined if occupational exposure of operating room personnel to waste anesthetic gases during cardiopulmonary bypass (CPB) complies with the established governmental limits. METHODS: Ten adults underwent inhalational anesthesia for coronary artery bypass grafting with nitrous oxide and either sevoflurane (n = 5) or desflurane (n = 5). The administration of inhalational anesthetic agents was stopped before initiation of CPB. Gas samples were obtained before and during CPB every 90 seconds from the breathing zones of anesthesiologist (A), surgeon (S), and perfusionist (P). Time-weighted averages (TWA) over the time of exposure were calculated. RESULTS: The surgeon's exposure to nitrous oxide was 9.3 +/- 1.9 parts per million (ppm) before and 3.0 +/- 1.4 ppm during CPB (A: 6.7 +/- 1.1 ppm and 0.5 +/- 0.1 ppm; P: 3.7 +/- 1.4 ppm during CPB). Occupational exposure to desflurane was 0.21 +/- 0.10 ppm before and 0.62 +/- 0.28 ppm during CPB for the surgeon (A: 0.02 +/- 0.01 ppm and 0.02 +/- 0.003 ppm; P: 0.82 +/- 0.26 ppm during CPB), thereby exceeding the given limit of 0.5 ppm. Exposure levels of sevoflurane were below the 0.5 ppm limit at all times, as were nitrous oxide levels (threshold limit: 25 ppm). CONCLUSIONS: Although occupational exposure to inhalational anesthetic agents was low at most times during the study and none of the operating room staff complained about subjective or objective impairment or discomfort, all measures must be taken to further minimize occupational exposure, including sufficient air conditioning and routine use of waste gas scavenging systems on CPB equipment.

Adult↗

Effect of anesthetic gas on middle ear fluid.

Tympanometry was performed before (preoperative) and after (intraoperative) the administration of inhalation anesthesia including nitrous oxide and halothane on 109 children undergoing myringotomy with pressure equalization tube insertion. A total of 213 preoperative tympanograms were compared with their intraoperative counterparts and the presence or absence of middle ear effusion at myringotomy. When preoperative tympanograms were consistent with pneumatized middle ears, intraoperative findings demonstrated a mean middle ear pressure increase of +147 daPa. When preoperative tympanometry suggested middle ear effusion, less than 1% demonstrated intraoperative tympanometric changes and/or findings at surgery that would support anesthesia clearing middle ear effusion. Preoperative tympanometric data were poor predictors of the presence or absence of effusion at myringotomy. The relationship between inhalation anesthetics (i.e., nitrous oxide and halothane) and middle ear fluids, and the reliability of tympanometry to predict middle ear effusion are discussed.

Acoustic Impedance Tests↗

Cough during emergence from isoflurane anesthesia.

UNLABELLED: We evaluated the effects of smoking history and albuterol treatment on the amplitude and frequency of cough during emergence from anesthesia. Before induction of anesthesia, 68 patients were randomized to receive two puffs of a placebo or two puffs of albuterol via a metered dose inhaler. Anesthesia was then induced with thiopental, fentanyl, and succinylcholine. The patients' tracheas were intubated with an 8.0 mm-endotracheal tube, and isoflurane administration was initiated. At the end of surgery, isoflurane was discontinued, and the pressure in the endotracheal tube cuff was monitored via the pilot balloon while the end-tidal isoflurane concentration was recorded. Of the 68 patients, 52 coughed before responding to command, but the incidence did not differ between smokers and nonsmokers (33 of 43 vs 19 of 25), nor did it differ between albuterol-treated and untreated patients. There was no difference in the frequency or amplitude of coughs between smokers and nonsmokers, nor did albuterol affect either variable. The mean end-tidal concentration at which cough first occurred was 0.30%+/-0.02%, and only 5% of patients coughed at values >0.6%. We conclude that 1) cough is frequent during emergence; 2) smoking does not affect emergence cough; 3) albuterol treatment does not affect emergence cough; and 4) patients are unlikely to cough at end-tidal values of isoflurane >0.6%. IMPLICATIONS: Most patients cough as they awaken from general anesthesia given via an endotracheal tube. In our study population, cough was frequent but generally did not occur until the end-tidal concentration of isoflurane was <0.6%. Smokers were no more likely to cough than nonsmokers, and the beta-adrenergic agonist albuterol did not prevent cough.

Albuterol↗