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The effect of midazolam premedication on discharge time in pediatric patients undergoing general anesthesia for dental restorations.

PURPOSE: The purpose of this study was to evaluate the effect of oral premedication with midazolam on recovery times of children undergoing dental restorations under general anesthesia. METHODS: The records of 106 children (1.2-11.3 years, ASA I or II) undergoing ambulatory dental restorations were randomly selected and retrospectively reviewed: 50 subjects received midazolam (M) 0.5 mg/kg orally approximately 30 minutes prior to their procedure and 56 control subjects received no premedication (C). General anesthesia consisted primarily of inhalational anesthesia. Time in the operating room (OR), post-anesthesia care unit (PACU) and same day surgery (SDS) were determined and compared between groups. RESULTS: Both groups were similar with respect to age and weight. There were no significant differences between groups in time spent in the OR, PACU or SDS (p>0.05). In a subset of children having shorter dental procedures (OR time < or =75 minutes, n=29), there remained no significant difference in discharge times between groups. CONCLUSIONS: Preoperative administration of oral midazolam does not delay discharge of children undergoing general anesthesia for dental rehabilitation.

Ambulatory Care↗

The comparative effects of sevoflurane versus propofol in the induction and maintenance of anesthesia in adult patients.

A randomized, prospective study was performed at four institutions to compare anesthetic induction, maintenance, and recovery characteristics between sevoflurane- and propofol-based anesthesia in 186 ASA physical status I and 11 patients undergoing elective surgical procedures of 1-3 h. Group 1 (n = 93) patients received sevoflurane-nitrous oxide for both induction and maintenance of anesthesia while Group 2 (n = 93) received propofol-nitrous oxide anesthesia. Induction of anesthesia and tracheal intubation times were significantly shorter with propofol (2.21 +/- 0.2 min, 5.11 +/- 0.3 min, respectively) than with sevoflurane (3.11 +/- 0.2 min, 7.21 +/- 0.3 min, respectively). Emergence times after sevoflurane (8.81 +/- 1.2 min) were significantly shorter than with propofol (13.21 +/- 1.2 min). Overall frequency of complication-free induction, maintenance, and emergence did not differ between the two anesthetic groups. However, side effects involving airway excitement were more prevalent during mask induction with sevoflurane as compared to propofol. Patients in the sevoflurane group were oriented and required postoperative analgesia much earlier than those who received propofol. Both groups were hemodynamically stable throughout the study period. The incidence of postoperative nausea, vomiting, and pain-discomfort scores were similar between the two groups. Urinary specific gravity decreased in the sevoflurane-treated group while serum creatinine and urinary pH were unchanged from preoperative values in both groups. Sevoflurane compared favorably with propofol when used for anesthesia for elective procedures of 1-3 h duration.

Adult↗

Local block for postoperative knee arthroscopy pain management: a retrospective study.

Knee arthroscopy is one of the most common orthopedic procedures done in the United States. It usually is performed as an outpatient procedure. This retrospective study was designed to assess the level of postoperative analgesia provided by the local knee block. According to the anesthesia technique received, 59 patients were categorized in group 1 (general anesthesia) or group 2 (general or monitored anesthesia care with local knee block). The severity of the knee pain was assessed using verbal pain rating scores during the anesthesia recovery period, before patients left the hospital, and again on the first postoperative day. Patients in group 2 had significantly lower pain scores compared with patients in group 1 during these periods. Results suggest that the local knee block provides superior postoperative analgesia for the knee arthroscopy patient.

Adult↗

Sevoflurane speeds recovery of baroreflex control of heart rate after minor surgical procedures compared with isoflurane.

UNLABELLED: Volatile anesthetics attenuate arterial baroreflex functions, whereas noxious stimuli may modify baroreflex-induced circulatory responses during anesthesia. We designed the present study to compare baroreflex control of heart rate during sevoflurane and isoflurane anesthesia in young healthy surgical patients. Baroreflex sensitivity was assessed in 24 patients randomized to receive either sevoflurane (n = 12) or isoflurane (n = 12) for general anesthesia. After an 8- to 10-h fast and no premedication, measurements of RR intervals obtained from electrocardiography and systolic blood pressure (SBP) measured through a radial artery catheter were made at conscious baseline (Awake), during end-tidal sevoflurane 2% or isoflurane 1.2% plus 67% nitrous oxide before incision (Anesth), during surgery at end-tidal sevoflurane 2% or isoflurane 1.2% plus 67% nitrous oxide (Surg), and 20 min after tracheal extubation (Recov). Baroreflex responses were triggered by bolus i.v. injections of phenylephrine (100-150 micrograms) and nitroprusside (100-150 micrograms) to increase and decrease SBP by 15-30 mm Hg, respectively. The linear portions of the baroreflex curves relating RR intervals and SBP were determined to obtain baroreflex sensitivities. Baroreflex sensitivities to both pressor and depressor tests were significantly depressed during Anesth and Surg periods compared with Awake values in both anesthetic techniques. The pressor test sensitivity during the Recov period returned to the Awake value after sevoflurane (12.9 +/- 3.7 vs 11.0 +/- 8.7 ms/mm Hg [mean +/- SD]) but was still depressed after isoflurane anesthesia (13.9 +/- 8.0 vs 4.8 +/- 3.2 ms/mm Hg; P < 0.05). The depressor test sensitivities during the Recov period remained depressed after both anesthetic techniques. We conclude that both sevoflurane and isoflurane depress arterial baroreflex function during anesthesia and surgery, but the pressor test sensitivity was restored more quickly after sevoflurane than after isoflurane anesthesia. IMPLICATIONS: Arterial baroreflex function is an important neural control system for maintaining cardiovascular stability. We found that baroreflex control of heart rate due to hypertensive perturbation returned to the preanesthetic level more quickly after sevoflurane than after isoflurane anesthesia.

Adult↗

The effect of supplemental oxygen on apnea and oxygen saturation during pediatric conscious sedation.

PURPOSE: This study compared the effect of supplemental oxygen (O2) on pediatric patients' apnea status and oxyhemoglobin saturation during: 1) conscious sedation for dental procedures and 2) the recovery period following sedation. METHODS: Fourteen child patients (mean age 42 months) sedated with 50 mg/Kg chloral hydrate, 25 mg hydroxyzine pamoate, and 1.5 mg/Kg meperidine were treated for two separate appointments. The patients received supplemental O2 via nasal cannulae at random at one of the two appointments. Following the operative period, all patients were monitored sitting upright for an additional 15 min. RESULTS: Intraoperative results showed that the risk of apnea was 39% (11/28), with apneic events distributed equally between O2 and non-O2 supplemented sedations. The overall risk of desaturation was 29% (8/28). Mean SpO2 was always elevated with O2 supplementation and the mean difference in O2 versus non-O2 was statistically significant. The risk of apnea in the postoperative period was 7% (1/14) for both the non-O2 and O2-supplemented patients. The risk of desaturation in the postoperative period was 11% (3/28) with one desaturation in a non-O2 and two desaturations in O2-supplemented patients. CONCLUSION: We conclude that intraoperative O2 supplementation prevents desaturations even in the presence of apnea during pediatric conscious sedation.

Adjuvants, Anesthesia↗

Psychomotor and clinical assessment of flumazenil as an antagonist of midazolam.

The benzodiazepine antagonist flumazenil (0.01 mg/kg) has been compared with doxapram (1 mg/kg) and saline for the reversal of anaesthesia with intravenous midazolam, alfentanil, nitrous oxide in oxygen and isoflurane. The completeness of reversal was assessed by means of a four-choice reaction time test, 1 and 3 h following the antagonist. In addition, the level of sedation was graded using a five-point scale. Psychomotor testing showed that 60 min after administration of the antagonist, there were marked increases in reaction times (P less than 0.05) both in the control and doxapram groups, but not in those receiving flumazenil. At 180 min, however, reaction times in all groups had returned to baseline values. In contrast, there was a significant difference in the sedation scores between the saline and flumazenil groups throughout the study period (P less than 0.05). During the 4 h following midazolam, there was no evidence of re-sedation in any of the groups despite the relatively high midazolam dosage.

Adolescent↗

Propofol and sevoflurane during epidural/general anesthesia: comparison of early recovery characteristics and pain relief.

We investigated the early recovery characteristics and pain relief of adult patients during combined anesthesia with (epidural and general), either with propofol or sevoflurane for maintenance in major abdominal surgery. Twenty-two patients (ASA I-III) were enrolled in this randomized, prospective study. After fluid preloading, 10 ml of bupivacaine 0.5% + 5 ml of prilocaine 0.5% + 1 ml of fentanyl 50 microg mL(-1) were administered via an epidural catheter. General anesthesia was induced with fentanyl and propofol after T6 sensorial blockade. Propofol group (n = 11) received propofol (2-5 mg kg(-1) h(-1)), sevoflurane group (n = 11) received sevoflurane (1-2%) for maintenance. Anesthesia was supplemented with N2O in O2 and intravenous fentanyl. Continuous epidural infusion of 0.125% bupivacaine + 1 microg fentanyl (5-7 mL h(-1)) was started forty-five min after the epidural bolus dose and 5 ml of it was given at the start of the wound closure. All anesthetics were discontinued except epidural infusion during the last suture. After emergence time was determined, the patients were transferred to the PACU. They were observed for orientation times of person and place. The pain scores (verbal analogue scale, 0-10) were assessed with 30 min intervals. When the patient's pain score was >3, rescue analgesic protocol (diclofenac Na 75 mg im followed by meperidine HCI approximately 0.25 mg kg(-1) iv at the latter period) was applied. In the case of inadequate pain relief during the latter assessment periods, meperidine HCI approximately 0.25 mg kg(-1) was administered. Mann-Whitney U test and Fisher's exact test were used for the statistical analysis. A value of p<0.05 was considered significant. Between the groups no statistical differences were observed in the emergence time (5 vs. 6 min, median) and in the orientation time to person (6 vs. 10 min). Recovery of orientation to place was found faster in propofol group (7 vs. 12 min, p = 0.041). Pain scores of the patients between the groups were not statistically different at 0, 30, 60, 90, 120 min postoperatively (3, 2, 3, 2, 2, and 2, 4, 4, 3, 3, respectively). Rescue analgesic protocol and additional meperidine HCI were applied to 63.6% and 45.4% of patients in the propofol group, 54.5% and 36.3% of patients in the sevoflurane group, respectively. There weren't any statistical differences in regard to these, either. Except orientation time to place, the times of emergence and orientation to person, the pain scores and the analgesic requirements of the patients in both groups were similar. Propofol or sevoflurane did not offer any advantages for postoperative pain relief on behalf of either one when combined with epidural anesthesia.

Abdomen↗

Outpatient orthognathic surgery: review of 205 cases.

PURPOSE: This article reviews the evolution of outpatient orthognathic surgery from 1988 to 1995 at the University of Texas Health Science Center at San Antonio. PATIENTS AND METHODS: A total of 328 patients had orthognathic surgery from 1988 to 1995. Two hundred and five (124 females, 81 males) were treated on an outpatient basis in the surgical suite of the dental school. Procedures included bilateral sagittal split osteotomies (BSSO), Le Fort I osteotomies (LFI), horizontal mandibular osteotomies (HMO), rapid palatal expansions (RPE), and combinations of the above. Additional procedures such as submental liposuction, blepharoplasty, dorsoseptorhinoplasty, and otoplasty were performed on 22 patients. Patient age ranged from 13 to 64 years, (average age 25). RESULTS: Ninety-four (46%) of the patients were discharged the day of surgery. One hundred and two (51%) were admitted for 23-hour observation, and five (2.4%) were admitted for longer than the 23-hour observation period. Anesthesia time over 4:28 significantly correlated with admission for observation status. There was no significant difference between LFI and BSSO in relation to admission for observation status. CONCLUSIONS: The number and complexity of orthognathic procedures increased dramatically over the study period. The length of anesthesia time, but not the specific procedure, correlated significantly with admission to observation status. There were few unexpected complications, with considerable cost reduction and convenience for the patients.

Adolescent↗

Recovery after paediatric daycase herniotomy performed under spinal anaesthesia.

In this prospective survey, recovery in hospital and at home was evaluated in 195 children aged 6 months to 10 years who had undergone herniotomy under spinal anaesthesia as a daycase procedure. Spinal anaesthesia was successful in most of the children, with only two patients being given general anaesthesia. Eighty-three percent of the children had pain at home and 19% had moderate or severe pain. Eighty-five percent of the children needed pain medication at home; the median dose of analgesics was 4 (1-9, 10th and 90th percentiles). Vomiting was noted in two of 195 children in hospital and in 10 of 192 children at home. Eleven children developed a mild position-dependent headache. Most of the children (183/191) recovered their normal daily activities during the first three postoperative days. We conclude that spinal anaesthesia is a safe and effective technique for paediatric herniotomy. Moreover, pain is common following herniotomy and children should be given analgesics for the first two or three postoperative days.

Activities of Daily Living↗

Retrobulbar block fails to prevent an increase in serum cortisol concentration on emergence from anaesthesia after cataract surgery.

We have studied 30 elderly patients undergoing cataract surgery, allocated randomly to receive general anesthesia, local anaesthesia by retrobulbar block or general anaesthesia combined with retrobulbar block given after induction. Retrobulbar block alone prevented the increases in circulating cortisol and glucose values which occurred in those patients receiving general anaesthesia alone. Retrobulbar block given after induction of general anaesthesia, however, suppressed the cortisol and glucose response during surgery, but did not prevent a marked increase in cortisol concentrations during the immediate postoperative period. The results suggest a hormonal response to emergence from anaesthesia which has hitherto been masked by the stress response to surgery itself.

Aged↗

Recovery of psychomotor function following general anaesthesia in children: a comparison of propofol and thiopentone/halothane.

The present study was undertaken to compare immediate recovery and recovery of complex psychomotor function in 20 children (aged 6-12 years) following general anaesthesia with either thiopentone/halothane or propofol. Early recovery of psychomotor skills was significantly faster in the propofol group than in the thiopentone/halothane group. Compared to preanaesthesia baseline the sedation and cooperation scores, the reaction time to visual and auditory stimuli as well as the postbox test and the flicker fusion frequency were less impaired after propofol than after thiopentone/halothane anaesthesia up to 120 min postoperatively. In the propofol group most tests reached preanaesthesia levels after 120 min, while in the thiopentone/halothane group these levels were not reattained throughout the entire study period. The results indicate that the recovery of psychomotor function in paediatric patients following general anaesthesia with propofol is significantly faster than with thiopentone/halothane. This has important implications for parental satisfaction, the time over which patients need to be monitored in the recovery room and for the discharge criteria after daycase surgery.

Anesthesia Recovery Period↗

[Premedication with intranasal midazolam in pediatric anesthesia].

To evaluate nasally administered midazolam 0.2 mg.kg-1 for preinduction of anaesthesia in paediatric patients the authors studied ASA 1 patients scheduled for elective surgery. Forty-five children, ages 3 to 126 months, were randomized in three groups: group D (n = 16) received diazepam 0.33 mg.kg-1 orally, group P (placebo) (n = 13) 0.04 ml.kg-1 normal saline via the nasal route; in group MDZ (n = 16) the children were given intranasal midazolam 0.3 mg.kg-1. The premedication was assessed on a 5-point sedation scale, modified to include the response to mask placement and the quality of the induction of general anaesthesia. The degree of sedation, heart rate, blood pressure, respiratory rate and oxygen saturation levels were recorded on the arrival in the operating room (0 min) and 3, 6, 9, 12 and 15 min (mask placement) after drug administration. With intranasal midazolam sedation was demonstrable at 6 min and was significant at 9 and 12 min. In this group all the children were calm or drowsy. The induction of anaesthesia was equivalent in group D and MDZ but easier than in those patients receiving normal saline. Vital signs did not change during the study period in any of the three groups. Intranasal midazolam was slightly more effective than oral diazepam. In children, it produces anxiolysis and sedation with rapid onset and is an attractive alternative to other routes for preanaesthetic medication.

Administration, Intranasal↗

Effects of the benzodiazepine antagonist flumazenil on postoperative performance following total intravenous anaesthesia with midazolam and alfentanil.

Postoperative performance following total intravenous anaesthesia (TIVA) using midazolam and alfentanil was studied with and without the administration of a single dose of a benzodiazepine antagonist, flumazenil (Ro 15-1788). Performance was compared with a reference group anaesthetized with thiopentone, alfentanil and nitrous oxide. All patients were assessed by use of a rating scale which took into account the degree of sedation, amnesia, comprehension and cooperation as well as temporal and spatial orientation. There was a slow recovery following TIVA with somnolence and amnesia lasting several hours. Administration of flumazenil 1.0 mg i.v. at extubation caused a significant reduction of sedation (P less than 0.001) during the first postoperative hour, with patients fully awake or only lightly sedated, but was later followed by resedation. The patients of the reference group were moderately sedated during the observation period. Five and six hours postoperatively there was no difference between the groups. Amnesia was more profound in the groups that received midazolam; the effect of the antagonist could only be seen for 15 min after its administration. Comprehension and cooperation, as well as orientation, were equally good in the antagonist and in the reference group during the immediate postoperative period, whereas in the TIVA group a gradual improvement over the first hours was seen. In the antagonist group there was no increase in the number of analgesic requirements, no anxiety attacks or other adverse effects. It is concluded that flumazenil offers an improvement in postoperative performance following TIVA induced by midazolam and alfentanil, but the effects are of short duration.

Alfentanil↗

Cardiovascular homeostasis during inhalational general anesthesia: a clinical comparison between sevoflurane and isoflurane. On behalf of the Italian Research Group on sevoflurane.

STUDY OBJECTIVE: To obtain more information on cardiovascular homeostasis and patient discharge from the recovery area after general anesthesia with either sevoflurane or isoflurane as the main anesthetic. DESIGN: Prospective, randomized, multicenter study. SETTING: Inpatient anesthesia at 13 University Departments of Anesthesia. PATIENTS: 247 ASA physical status I, II, and III patients, aged 18 to 85 years, receiving general anesthesia for elective urological, orthopedic, ENT, vascular, and low abdominal surgery. INTERVENTIONS: General anesthesia was maintained using a 60% nitrous oxide in oxygen mixture with either isoflurane (n = 125) or sevoflurane (n = 122) adjusted according to hemodynamic variables. MEASUREMENTS AND MAIN RESULTS: Occurrence of hypotension [systolic arterial blood pressure (SBP) decrease >30% from baseline], hypertension (SBP increase >30% from baseline), bradycardia [heart rate (HR) <50 bpm], or tachycardia (HR>100 bpm) provoked stepwise changes in the inspired concentration of the study drug. If this action proved to be ineffective after an adequate stabilization period, a specific treatment was given, and the need for pharmacological treatment was recorded as a hemodynamic side effect by an independent observer. No differences in duration of anesthesia were observed between sevoflurane (126 +/- 76 min) and isoflurane patients (139 +/- 60 min). Mean duration from anesthetic discontinuation to fulfillment of discharge criteria was shorter after sevoflurane (21 min; 25(th) to 75(th) percentiles: 27 to 13 min) than isoflurane (27 min; 25(th) to 75(th) percentiles: 17 to 35 min) (p < 0.0005). Hemodynamic side effects requiring therapy occurred in 18 sevoflurane patients (14.6%) and 26 isoflurane patients (20.8%) (p = NS). The risk for hemodynamic side effects increased with age (>50 vs. < or OFFyrs: odds ratio 2.5; 95% CI 1.2 to 5.4; p = 0.015) and ASA physical status (III vs. I and II: odds ratio 2.2; 95% CI 0.9 to 5.7; p = 0.048). When only patients over 50 years of age were considered (72 in the sevoflurane group and 79 in the isoflurane group), the incidence of hemodynamic side effects was higher with isoflurane (29.1%) than with sevoflurane (15.2%) (odds ratio 2.3; 95% CI 1.0 to 5.2; p = 0.04). CONCLUSIONS: Sevoflurane provided equally safe and effective control of cardiovascular homeostasis as isoflurane, with a more rapid discharge from the recovery area. Interestingly, patients over 50 years of age showed a lower risk for hemodynamic side effects when receiving sevoflurane than isoflurane.

Adolescent↗

Recovery times and side effects after propofol infusion and after isoflurane during ear surgery with additional infiltration anaesthesia.

Two anaesthetic procedures that did not include nitrous oxide were compared in a randomised study of 50 patients for tympanoplasty and tympanoscopy: propofol given for induction and maintenance, and thiopentone-isoflurane given for induction and maintenance, respectively. Induction in the first group was with a bolus injection of propofol and the same agent was given for the duration of anaesthesia by continuous intravenous administration. Thiopentone was given until loss of the eyelash reflex and anaesthesia maintained with isoflurane 0.4-2.0%. Analgesia was achieved in both groups by fentanyl given intravenously and by local injection of mepivacaine with ornipressin. The two patient groups were analysed for age, sex and weight as well as for side effects during the induction, maintenance and recovery periods, such as coughing, vomiting, venous pain, spontaneous movements, singultus, headaches, dysrhythmias and psychic disorders possibly due to anaesthesia. Side effects were moderate in both groups. Recovery time was statistically significantly shorter in the propofol group and the patients in this group appeared to be much more aware after recovery than those in the thiopentone-isoflurane group.

Adolescent↗

A clinical trial of long-acting local anesthetics for periodontal surgery.

The efficacy of long-acting local anesthetics for anesthesia during periodontal surgery and for analgesia during the immediate postoperative period was evaluated. The rationale for using long-acting local anesthetics such as etidocaine and bupivacaine is that they can provide surgical anesthesia and, because of their long duration, prevent discomfort that may occur for 4-6 hours postoperatively. Two clinical trials were performed. The first enrolled patients requiring bilateral periodontal surgery. Using a matched pair design and double-blind randomized study conditions, 2% lidocaine 1/100,000 epinephrine was compared with 1.5% etidocaine 1/200,000 epinephrine for periodontal surgery. The time until complete recovery and the time until pain onset were found to be longer for the etidocaine surgeries. Postoperative pain appeared more severe, and the need for oral analgesics was greater for the lidocaine surgeries. Surgeons' rating of surgical bleeding was significantly greater for the etidocaine procedures. When matched bilateral surgeries were not available, a second double-blind randomized parallel trial was performed that compared 1.5% etidocaine 1/200,000 epinephrine to 0.5% bupivacaine 1/200,000 epinephrine. No significant differences were seen in the quality of anesthesia, degree of bleeding, or postoperative pain between these two long-acting anesthetics.

Adult↗

Recovery after oral surgery with halothane, enflurane, isoflurane or propofol anaesthesia.

We have compared the recovery characteristics of four different techniques for maintenance of anaesthesia in 99 day-case patients admitted for oral surgery. All patients received propofol for induction of anaesthesia followed by halothane, enflurane, isoflurane or propofol infusion for maintenance of anaesthesia. Each patient was subjected to a battery of psychometric tests which included Spielberger state, trait, mood stress and mood arousal questionnaires, Maddox-Wing test and five-choice serial reaction time. All tests were performed before operation and at 0.5, 1, 2, 4, 24 and 48 h after operation. Performance in the reaction time test decreased significantly in the immediate postoperative period, returning almost to preoperative values by 4 h. However, only those patients who received enflurane or propofol had returned to their performance level before surgery by 4 h, although all four groups had achieved this target by 24 h. There was a further improvement in performance at 48 h. Anxiety and stress were high before surgery and decreased rapidly in the postoperative period. The Maddox-Wing test demonstrated a significant impairment in performance in the first 1 h after surgery, which returned to normal by discharge at 4 h. There were no significant differences between the four groups in these latter tests.

Adult↗

[The washout behavior of isoflurane following balanced anesthesia and its effect on postoperative oxygen supply].

Few studies have described the pharmacokinetics and pharmacodynamics of isoflurane (I) during the postoperative recovery room stay. In this study the influence of balanced anesthesia with I on the postoperative course was investigated by studying pulmonary washout of I and its effect on arterial oxygen saturation. METHODS. Following institutional approval and informed consent, 50 patients (ASA I and II) scheduled for lateral fenestration for intervertebral disc herniation participated; all had no previous record of cardiopulmonary problems. Induction of anesthesia was achieved with intravenous alcuronium 0.03 mg/kg, fentanyl 0.003 mg/kg, thiopental 5 mg/kg, and succinylcholine 1.5 mg/kg followed by alcuronium 0.09 mg/kg before changing to the prone position. Anesthesia was maintained with controlled ventilation in a rebreathing system (fresh gas flow FGF) = 3.01/min, FIO2 = 0.3 in N2O, plus 0.8 Vol.-% cIet = 1.3 MAC). Near the end of surgery I was discontinued and IGI was increased to 61/min O2 for 10 min. Patients then returned to breathing ambient air. Extubation was carried out as soon as a minimum tidal volume of 400 ml was obtained. End tidal I concentration (cIet; Vol.-%) was measured by infrared absorption (Normac, Datex) and O2 saturation by pulse oximetry (Biox III, Ohmeda). Datum point of the pulmonary I-washout curve was the mean end-tidal I concentration obtained 15 min before terminating I (cIAW). Effects of duration of anesthesia, Broca index, and amount of I administered (tidal volume x inspiratory I concentration x min; ml) on I-washout were assessed. A pulse-oximetric O2 saturation of less than 90% was regarded as hypoxygenation. RESULTS. Mean duration of anesthesia for both males and females was 85 +/- 25 min, mean Broca index 102 +/- 13. The amount of I administered with the inspiratory volume was 5.661 +/- 2.194 1 I (1.0 +/- 0.4 Vol.-%). Mean I-regression (Fig. 3) was 236 x 10(-5) Vol.-%/min (Figs. 1 and 3). Mean I-washout 60 min after extubation was 44.6 +/- 15.2% of the administered amount. Adequate spontaneous breathing began a mean of 17 min after the end of I exposure, corresponding to 20% cIet of washout. All patients were extubated after a mean of 22 min at a mean etI of 17% of washout. After extubation, pulse oximetry indicated hypoxygenation in 18 patients (= 36%) during 2 periods (Fig. 4): (1) at a mean cIet of 0.1 Vol.-% (= 15% of washout) after a mean of 8 min; and (2) at a mean cIet of 0.08 Vol.-% (= 12% of washout) a mean of 19 min following extubation. Further episodes of hypoxygenation occurred as much as 40 min post-extubation. (ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗