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M Georgieff

Publications and source records attributed to M Georgieff.

At least 73 records · Page 4Linked to original sources
PubMed1999

[Development of a new closed-loop system for controlling mivacurium-induced neuromuscular blockade].

UNLABELLED: There are many closed-loop control systems for muscle relaxants reported, but only a few could cope with the introduction of the latest shorter acting neuromuscular blocking drugs. These new muscle relaxants such as mivacurium require a fast adapting closed-loop system for controlling an adequate infusion. METHODS: After approval of the local ethics committee and having the patients' informed consent a total number of 75 patients [ASA I and II] were included in the study and assigned either to a training-, prediction-, prediction-/feedback- or a validation phase, as needed. Anaesthesia was induced and maintained with propofol in a TCI-mode with a plasma level of 3 to 5 micrograms/ml and 0.1 mg fentanyl boli as needed in all patients. In the last validation phase, having 20 patients, the prediction error and the error of the whole system was taken and analysed. RESULTS: A closed-loop system using a neural network as a predictor could be established. In the final validation phase consisting of 20 patients the mean square prediction error was found to be 0.1% +/- 0.2% [mean +/- SD]. The mean square error of the whole system was 0.55% +/- 0.59% [mean +/- SD]. CONCLUSIONS: A closed-loop system for control of a mivacurium infusion could be established. The system proofed to be reliable for a closed-loop infusion of mivacurium in order to maintain a predefined degree of neuromuscular blockade of 95% during routine surgery. The performance of the described controller is comparable to all recent attempts and could therefore be useful for scientific studies. It should be further validated and established for other muscle relaxants, as well.

Adolescent↗
PubMed1999

[Validation of a risk score for prediction of vomiting in the postoperative period].

BACKGROUND: A risk score to predict postoperative vomiting was presented in a recent issue of this journal. In the present study this score was evaluated at another hospital under different surgical and anaesthetic conditions. Furthermore, we examined whether the score, which was originally designed to predict the occurrence of postoperative vomiting (POV) only, is also useful for prediction of postoperative nausea and vomiting (PONV). METHODS: The risk score was applied to 226 patients undergoing inpatient orthopaedic surgery under standardised general anaesthesia (propofol, desflurane in N(2)O/O(2), fentanyl, vecuronium, postoperative opioid analgesia). For 24 hours postoperatively, the patients were followed up for the occurrence of nausea, retching, and vomiting. Perioperatively, risk factors for POV were recorded (gender, age, smoking habits, history of previous PONV or motion sickness, duration of anaesthesia). Using these risk factors the individual risk for suffering POV was calculated for each patient. With these data two ROC-curves (for prediction of POV and PONV respectively) were constructed and the area under the ROC-curve (AUC) as a means of the prediction probabilities of the score was calculated. RESULTS: The incidence of POV as predicted by the score (22,8%) fits well to the actual incidence of this event (19,5%). The score predicts the occurrence of POV significantly better than can be expected by a random estimation. In spite of different surgical and anaesthetic conditions, the accuracy of the prediction in the present dataset was not significantly different from that reported by the authors of the scores in their validation set. Furthermore, the prediction properties for POV (AUC: 0,73) were not different from the prediction of PONV (AUC: 0,72). CONCLUSION: The present risk score provides valid prognostic results even under modified surgical and anaesthetic conditions, and, thus, may obviously be applied to other institutions. Furthermore our results support the hypothesis, that individual risk factors rather than the type of surgery or anaesthetic management have a major impact on the occurrence of POV and PONV.

Adult↗
PubMed1999

[The incidence of perioperative events with optimized documentation discipline].

AIM: The German Society of Anesthesiology and Intensive Care Medicine evaluated the standardized reporting of perioperative anaesthesia-related incidents, events, and complications (IEC). As part of the data validation efforts, the problem of variation in documentation procedure was evaluated. METHODS: A study group of particularly motivated and instructed residents and attendants was scrutinized at a University teaching hospital from April through June 96. IEC assessment was completed according to the Society's definitions. RESULTS: Out of 4242 anaesthetics during the study period 839 (19.8%) were completed by the study group. In the univariate analysis, the incidence of IECs was significantly (P < 0.001) more reported by the physicians studied (36.4%) than by the control group (18.6%). In a multivariate analysis, while adjusting for all covariables, reported incidence of IEC was 2.4-fold significantly increased (P < 0.001). CONCLUSIONS: This study is another step in validating the assessment of IECs. The results gain importance with respect to upcoming nationwide quality comparisons among anaesthesia providers. In addition, they give a better estimate of economic implications from IECs within the institution.

Analysis of Variance↗
PubMed1999

Interaction modeling of propofol and sufentanil on loss of consciousness.

STUDY OBJECTIVES: To examine the possible pharmacodynamic interaction of propofol and sufentanil with respect to the induction of loss of consciousness. DESIGN: Prospective, randomized, double-blinded study. SETTING: University hospital. PATIENTS: 30 female, ASA physical status I and II patients undergoing elective gynecologic surgery. INTERVENTIONS: Patients were allocated randomly to receive an individual combination of propofol (1, 2, 3, 4, 5, or 6 micrograms/ml) and sufentanil (0.1, 0.2, 0.3, 0.5, or 1.0 ng/ml) target blood concentrations using target-controlled infusions. MEASUREMENTS AND MAIN RESULTS: Study endpoint was loss of consciousness, which was tested by response to verbal commands and classified as responder or nonresponder, as assessed by the anesthetist, who was blinded to the drugs' target blood concentrations. Nonlinear association (interaction) of both drugs was accomplished with logistic regression analysis using the maximum likelihood method, based principally on the hypothesis of interaction: In [p/(1-p)] = beta 0 + beta 1 x Cprop + beta 2 x Csuf + beta 3 x Cprop x Csuf with a p-value < 0.05 for coefficient estimates considered significant. In the logistic regression model, sufentanil and propofol showed no supra-additive interaction regarding loss of consciousness (p = 0.5916). CONCLUSIONS: Our results give no evidence of additional hypnotic properties of sufentanil compared to the other fentanyl congeners, although logistic regression may be of limited value in modeling interaction of hypnotic-analgesic combinations.

Adult↗
PubMed1999

Neurobehavioral evidence for working-memory deficits in school-aged children with histories of prematurity.

Cognitive performance in 7- to 9-year-old preterm neonatal intensive-care survivors was compared with that in age-matched control children. Non-verbal memory span, spatial working-memory abilities, planning, set-shifting, and recognition memory for both spatial and patterned stimuli were assessed using the Cambridge Neuropsychological Testing Automated Battery. Relative to children in the control group, neonatal intensive-care unit (NICU) survivors demonstrated 25% more memory errors on the spatial working-memory task. Their use of strategy on this task was similar to a control group of 5-year-olds. Planning times on 'Tower of London' problems were long relative to those of term controls. NICU survivors demonstrated poorer pattern recognition as well as a shorter spatial memory span. The groups did not differ in visual-discrimination learning or in spatial-recognition memory. No specific neonatal risk factor accounted for the observed differences, although scores on the Neurobiological Risk Score (NBRS), a composite measure of neonatal risk, did predict several aspects of later task performance. Whether these data reflect a developmental delay in brain maturation in NICU survivors or the presence of a permanent information-processing deficit due to adverse neonatal events must be assessed through continued follow-up.

Child↗
PubMed1999

Nonlinear model-based predictive control of non-depolarizing muscle relaxants using neural networks.

Neuromuscular blockade can be relatively easily measured in the clinical setting. Consequently, closed-loop control can be exercised by measuring the neuromuscular activity, calculating the dose of drug necessary to achieve a predefined degree of neuromuscular blockade and finally directing an infusion pump. Recently introduced short-acting blocking agents like mivacurium provide benefits for the clinical routine due to a small onset time and half life. In order to provide a stable blockade for different groups of patients a fast and highly adaptable control unit is needed. Furthermore its development should not imply costly investigations for determining a pharmacological model. The fulfilling of these requirements yield a self-adapting model-based predictive control system. The application of artificial neural networks allows an appropriate adjustment of specific parameters without the knowledge of inner pharmacodynamic processes. In a clinical study the EMG module within a Datex AS/3 monitor was used to measure the blockade and a Grasepy 3500 infusion pump for i.v. administration of mivacurium to 35 patients (ASA I-III). The performance of the novel system (mean of the T1 error: -0.32 +/- 1.7) compares favourably with closed-loop controllers demonstrated in the past. These promising results and the easy adaption to other blocking agents encourage to apply this technology even for delivering hypnotic drugs.

Electromyography↗
PubMed1999

Perioperative transcutaneous pacemaker in patients with chronic bifascicular block or left bundle branch block and additional first-degree atrioventricular block.

BACKGROUND: Complete heart block is dreaded perioperatively in patients with chronic bifascicular or left bundle branch block (LBBB) and additional first-degree A-V block. Our aim was to investigate the necessity as well as the efficacy and safety of transcutaneous pacing in the perioperative setting. METHODS: Thirty-nine consecutive patients with asymptomatic chronic bifascicular block or LBBB and prolongation of the P-R interval scheduled to undergo surgery under anesthesia were prospectively enrolled in the study. Preoperatively, a transcutaneous pacemaker (PACE 500 D, Osypka Co.) was applied; its efficacy was checked with intra-arterial blood pressure measurement; the pain level was recorded. Additionally, 24-h Holter monitoring (CM2, CM5) was applied. Occurrences of a block progression or a bradycardia of <40 beats/min with hemodynamic impairment were the defined end points. RESULTS: Thirty-seven of the 39 patients (95%) could be successfully stimulated with a median current strength of 70 mA; whereby 33 of the 39 patients felt moderate to severe pain. There was no perioperative block progression. Three cases of brady-cardia of <40 beats/min with a critical drop in blood pressure occurred; but these patients were successfully treated with drug therapy without pacemaker stimulation. CONCLUSION: The perioperative application and testing of the pacemaker was safe and could be performed in nearly all patients successfully. However, we do not consider a routine prophylactic transcutaneous placement in patients with chronic bifascicular or LBBB and additional first-degree A-V block justified. Nevertheless, appropriate drugs and temporary pacemaker equipment should be easily accessible.

Aged↗
PubMed1999

Peri-operative tolerance to large-dose 6% HES 200/0.5 in major urological procedures compared with 5% human albumin.

We studied the long-term efficacy and safety of medium-molecular-weight hydroxyethyl starch (HES) administered in doses above 20 ml.kg-1 during major blood replacement therapy. Blood replacement for 50 patients used 6% HES 200/0.5 (HES group) or 5% albumin (ALB group) and additional blood components according to a defined protocol. We compared safety, efficacy and costs in 4 peri-operative days. Colloid administration on the day of surgery was 38.4 ml.kg-1 (HES group) and 35.1 ml.kg-1 (ALB group). Haemodynamic, coagulation and renal function parameters were similar. Although total serum protein was still different on the third postoperative day (53.45 gl-1 (HES group) and 60.6 gl-1 (ALB group) (p < 0.01)) the colloid osmotic pressure always remained above 19.5 (2.5) mmHg (HES group). Blood loss (3810 (1632) ml (HES group) and 3455 (1733) ml (ALB group)) and the requirement for blood components was comparable. Costs were reduced by 35% (p < 0.05) in the HES group. We conclude that using 6% HES 200/0.5 as the only colloid for treatment even of large blood loss is a safe and economic alternative to albumin.

Adult↗
PubMed1999

Dimenhydrinate for prevention of post-operative nausea and vomiting in female in-patients.

Dimenhydrinate is an inexpensive antihistaminic drug, that is frequently used as an anti-emetic during anaesthesia. The popularity of the drug is contrasted by the lack of modern studies concerning its efficacy in reducing the incidence of post-operative nausea and vomiting. Thus, dimenhydrinate was compared with placebo in this prospective, randomized, double-blind study. One hundred and thirty-three female in-patients were studied. They were stratified according to the type of surgery (laparoscopic cholecystectomy, thyroid resection or knee arthroscopy) to ensure an homogeneous distribution in both groups. General anaesthesia was induced with etomidate, fentanyl, vecuronium and maintained with enflurane in N2O/O2. Neuromuscular block was reversed with pyridostigmine/atropine. Patients in the dimenhydrinate group (n = 67) received 62 mg dimenhydrinate intravenously after induction of anaesthesia. Placebo patients (n = 66) received saline. Administration of dimenhydrinate (and placebo) was repeated three times during the 48-h study to mitigate the short half-life of the drug. Post-operative analgesia and anti-emetic rescue medication was standardized. Episodes of vomiting, retching and the need for additional anti-emetics were recorded. Nausea was assessed using a 10-cm visual analogue scale. Post-operative nausea and vomiting was rated as 'none', 'mild', 'moderate' and 'severe' using a fixed scoring algorithm. There were no differences between the two groups with regard to biometric data, type of surgery and distribution of risk factors for developing post-operative nausea and vomiting. In the dimenhydrinate group, more patients remained completely free from post-operative nausea and vomiting compared with placebo (dimenhydrinate: 38.8%; placebo: 15.1%; P = 0.004). The incidence of severe post-operative nausea and vomiting was also reduced from 39.4% to 14.9%. No relevant side effects were observed. Intra-operative dimenhydrinate, followed by three further administrations after surgery, reduces the incidence and the severity of post-operative nausea and vomiting without side effects. However, there still remained an unacceptable high number of patients who were not prevented completely from experiencing post-operative nausea and vomiting.

Adult↗
PubMed1999

Droperidol and dimenhydrinate alone or in combination for the prevention of post-operative nausea and vomiting after nasal surgery in male patients.

Droperidol and dimenhydrinate are inexpensive antiemetic drugs. Droperidol, especially, has been studied extensively, but there are no studies on the combination of both drugs for prevention of post-operative nausea and vomiting. One hundred and forty male hospitalized patients undergoing nasal surgery were randomized to receive one of four anti-emetic regimes: placebo, dimenhydrinate (1 mg kg-1), droperidol (15 micrograms kg-1), or the combination of both drugs (droperidol 15 micrograms kg-1 + dimenhydrinate 1 mg kg-1) administered after induction of anaesthesia. Patients in the dimenhydrinate-group and the combination-group received a second dose of dimenhydrinate 6 h after the first administration to mitigate the short half-life of the drug. For general anaesthesia a standardized technique, including benzodiazepine premedication, propofol, desflurane in N2O/O2, vecuronium, and a continuous infusion of remifentanil, was used. Post-operative analgesia and anti-emetic rescue medication were standardized. Episodes of vomiting, retching, nausea, and the need for additional anti-emetics were recorded for 24 h. The main endpoint of this study was the number of patients who were completely free of post-operative nausea and vomiting (Fisher's Exact Test). Furthermore, the severity of post-operative nausea and vomiting was analysed using a standardized scoring algorithm. The incidence of patients completely free of post-operative nausea and vomiting was 62.9% in the placebo-group, 77.1% in the dimenhydrinate-group (P = 0.21), and 82.9% in the droperidol-group (P = 0.07). This increased to 94.3% in the combination-group (P = 0.0015). In all three treatment groups the severity of post-operative nausea and vomiting was reduced significantly compared with placebo treatment (P = 0.0003). The incidence of side effects was similar in the four groups. Dimenhydrinate was ineffective in reducing the incidence of post-operative nausea and vomiting and droperidol only reduced the severity of post-operative nausea and vomiting. However, the combination of both drugs significantly reduces the incidence of post-operative nausea and vomiting when compared with placebo treatment.

Adult↗
PubMed1999

[Cost analysis concerning MRSA-infection in ICU].

OBJECTIVE: MRSA-infection incidences are still rising, because of unreflected use of antibiotic drugs in man and animals. Although some European countries already have an incidence as high as 30% of MRSA infection in ICU-patients, there is no additional financial support for the treatment of MRSA infected patients. METHODS: We investigated all MRSA infected patients of the operative ICU ward of the department of anaesthesia at the university Ulm within the last three years. We calculated all costs for decontamination and special treatment of the MRSA infection as well as the costs for closing beds, because of MRSA precaution and isolation reasons. RESULTS: The average monthly costs for MRSA infected patients is about 3848 EURO for decontamination and treatment, and another 5560 EURO fix costs. The average monthly ICU duration for MRSA patients was 5.8 days, which means a financial loss of 1622 EURO per "MRSA-patient day". This loss is more than two times the price the social security system pays for an ICU-patient. CONCLUSION: These extra costs should be calculated and additionally paid for patients with MRSA-infection in order to obtain a certain quality standard. By achieving this standard the total economy costs for MRSA infection treatment could be reduced.

Humans↗
PubMed1999

[Dimenhydrinate and metoclopramide for prevention of nausea and vomiting following septorhinoplasties in women].

OBJECTIVES: Dimenhydrinate and metoclopramide are inexpensive antiemetic drugs. Metoclopramide, especially, has been studied extensively in the past, but there are no studies that used the combination of both drugs for prevention of postoperative nausea and vomiting (PONV). METHODS: 120 female inpatients undergoing endonasal surgery were randomised to receive one of four antiemetic regimes: placebo, dimenhydrinate (1 mg x kg-1), metoclopramide (0.3 mg x kg-1), or the combination of both drugs (1 mg x kg-1 + 0.3 mg x kg-1) were administered intravenously after induction of anaesthesia and repeated 6 hours after the first administration. For general anaesthesia a standardised technique including benzodiazepine premedication, propofol, desflurane in N2O/O2 vecuronium and a continuous infusion of remifentanil was used. Postoperative analgesia (diclofenac or metamizole supplemented with piritramide) and antiemetic rescue medication (dolasetron and droperidol) were standardised. Episodes of vomiting, retching, nausea, and the need for additional antiemetics were recorded in the recovery room and 2, 5, 8, and 24 hours after surgery. The main goal of the study was to increase the number of females staying completely free from PONV (Chi 2-test). Furthermore, the severity of PONV was analysed, using a standardised scoring algorithm. RESULTS: There were no differences between the two groups with regard to biometric data and distribution of risk factors for developing PONV. In all four groups nearly the similar number of patients stayed completely free from PONV: Placebo: 60.7%, metoclopramide: 66.7%, dimenhydrinate: 64.3%, combination: 64.4% (differences not significant). There was also no difference in the severity of nausea and emetic sequel. DISCUSSION: In females undergoing endonasal surgery under propofol-desflurane-remifentanil anaesthesia the incidence of PONV is about 40%. In this setting, both metoclopramide and dimenhydrinate were ineffective to reduce the incidence and the severity of PONV. The combination of both drugs revealed no additional synergistic effect.

Adult↗
PubMed1999

[Meta-analysis of controlled randomized studies on droperidol for prevention of postoperative phase vomiting and nausea].

OBJECTIVE: Randomised, controlled trials using prophylactic droperidol to prevent postoperative nausea and vomiting (PONV) were included in a meta-analysis to estimate efficiency and dose-response of treatment. MATERIALS AND METHODS: Studies were systematically extracted from Medline, the manufacturer's database, and a supplemental search of references lists and current issues of locally available anaesthesia journals. Complete prevention of PONV defined as absence of nausea, retching, and vomiting within 6 hours (early PONV) and within 48 hours (late PONV) was chosen as the main end point. Additional information such as dose of droperidol, time and way of administration, and biometric data of the patients were extracted from each study. The pooled relative risk and the number-needed-to treat (NNT) were calculated. RESULTS: A total of 72 studies with 107 comparative subgroups were accepted for analysis according to the prospectively defined criteria. Of these sixty-nine trials reported a lower incidence of PONV with droperidol. The incidence of early and late PONV among the 5370 patients receiving droperidol was 23.4% and 38.2%, respectively. The corresponding incidence among the 3954 control patients was 40.7% and 53.9%. The relative risk for patients receiving prophylactic droperidol of suffering from early PONV was 0.58 and 0.71 for late PONV. The NNT for preventing one patient from PONV was 5.8 and 6.4 for early and late PONV, respectively. Treatment with droperidol was more effective when the baseline risk for PONV was higher than 25% for early PONV and 35% for late PONV. Under these circumstances the NNT was between 2.6 and 5.6. There was no dose response relationship for droperidol when the drug was applied in doses ranging from 0.5 to 300 micrograms.kg-1 body weight. It was not possible to derive reliable information about the incidence of side-effects of the droperidol administration. CONCLUSION: Droperidol is an effective antiemetic drug. The drug can be administered to patients with an increased risk of suffering from PONV without antiemetic prophylaxis. Since a positive dose response is lacking, droperidol should only be administered in doses of 1 mg or less.

Algorithms↗
PubMed1999

[Dolasetron, droperidol and a combination of both in prevention of postoperative nausea and vomiting after extracapsular cataract extraction under general anesthesia].

BACKGROUND: Both, droperidol and the new 5-HT3-antagonist (e.g. dolasetron) are effective drugs in the prevention of postoperative nausea and vomiting (PONV). It was the aim of this prospective double blind placebo controlled study to determine the efficacy of low-dose droperidol, dolasetron, and a combination of both drugs in the prevention of PONV after extracapsular cataract extraction. METHODS: 148 inpatients undergoing cataract surgery were stratified according to gender and then randomised to receive one of four antiemetic regimens: placebo, droperiodol (10 micrograms x kg-1), dolasetron (12.5 mg), or the combination of both drugs (10 micrograms x kg-1 + 12.5 mg). The drugs were administered intravenously 5-10 minutes before the end of anaesthesia. General anaesthesia and the perioperative management of the patients were standardised: benzodiazepine premedication, induction with etomidate, alfentanil and mivacurium. Maintenance using desflurane in N2O/O2, and a continuous infusion of mivacurium was used. Postoperative analgesia (diclofenac or paracetamol) and antiemetic rescue medication (dimenhydrinate and metoclopramide) was standardised. Nausea, episodes of vomiting, retching and the need for additional antiemetics were recorded for 24-hours. The severity of PONV was categorised using a standardised scoring algorithm. The main aim of the study was the number of patients who stayed completely free from PONV. RESULTS: There were no differences between the two groups with regard to biometric data, type of surgery, and distribution of risk factors for developing PONV. In all three treatment groups significantly less patients suffered from PONV (placebo: 66%; droperidol: 89%, dolasetron: 92%, combination: 89%; p = 0.011). Furthermore, the severity of PONV was reduced (p = 0.012). CONCLUSION: Low-dose droperidol and dolasetron are equally effective to reduce the incidence of PONV after cataract surgery under general anaesthesia. The combination of both drugs revealed no additional effect.

Aged↗
PubMed1999

Comparison between the oral and intravenous L-[1-13C]phenylalanine breath test for the assessment of liver function.

To simplify the L-[1-13C]phenylalanine breath test which is used to assess liver function the tracer is usually given orally, and CO2 production rate is estimated. In 12 healthy volunteers and 10 liver cirrhotics we compared the oral approach with i.v. tracer administration combined with measurement of individual CO2 production rate. The 13CO2/12CO2 enrichment was assessed by isotope-ratio mass spectrometry. After i.v. [1-13C]phenylalanine application exhaled 13C recovery per minute peaked within 10 minutes (controls: 0.17 +/- 0.06%; cirrhotics: 0.05 +/- 0.02%, p < 0.01). The oral approach yielded comparable separation between 30-60 minutes, with average peak values being 0.18 +/- 0.03% and 0.06 +/- 0.03% (p < 0.01), respectively. Variable gastrointestinal resorption kinetics after oral application probably causes this difference.

Administration, Oral↗
PubMed1999

The impact of minor perioperative anesthesia-related incidents, events, and complications on postanesthesia care unit utilization.

UNLABELLED: The German Society of Anesthesiology and Intensive Care Medicine evaluates the standardized and routine reporting of perioperative anesthesia-related incidents, events, and complications (IEC). As part of the long-term project's definitions, IECs are graded according to severity and to their clinical consequence on further postanesthesia monitoring and treatment demands. The adult study population of our department comprised 37,079 patients recovering from anesthesia in a tertiary university hospital from July 1992 through June 1997. Cardiac, obstetric, craniotomy, thoracotomy, laparotomy, and emergency operations were excluded. Multivariate regression statistics were used to calibrate the impact of minor graded IECs on necessary postanesthesia care unit (PACU) utilization. Minor and severe IECs appeared in 22.1% and 0.2% of the patients. A minor IEC occurrence was a statistically significant (P < 0.001) predictor of PACU utilization in a multivariate regression model. The mean difference of PACU length of stay for patients with minor IECs was prolonged by a range of 6%-26% when adjusted for coexisting severity features such as age, gender, ASA physical status, and type and duration of anesthesia and surgery. We conclude that the IEC methodology integrates epidemiologic information about perioperative anesthesia outcome. Minor but frequently occurring IECs have an impact on PACU utilization and are thus important to measure and follow. IMPLICATIONS: It is desirable to know how anesthesia-related incidents, events, and complications influence postanesthesia care. Analyses of standardized and routine perioperative outcome data, as proposed by the German anesthesia quality project, can show that even minor events consume relevant resources and are thus important to measure and follow.

Adolescent↗
PubMed1999

Continuous arterial P(O2) and P(CO2) measurements in swine during nitrous oxide and xenon elimination: prevention of diffusion hypoxia.

BACKGROUND: During nitrous oxide (N2O) elimination, arterial oxygen tension (PaO2) decreases because of the phenomenon commonly called diffusive hypoxia. The authors questioned whether similar effects occur during xenon elimination. METHODS: Nineteen anesthetized and paralyzed pigs were mechanically ventilated randomly for 30 min using inspiratory gas mixtures of 30% oxygen and either 70% N2O or xenon. The inspiratory gas was replaced by a mixture of 70% nitrogen and 30% oxygen. PaO2 and carbon dioxide tensions were recorded continuously using an indwelling arterial sensor. RESULTS: The PaO2 decreased from 119+/-10 mm Hg to 102+/-12 mm Hg (mean+/-SD) during N2O washout (P<0.01) and from 116+/-9 mm Hg to 110+/-8 mm Hg during xenon elimination (P<0.01), with a significant difference (P<0.01) between baseline and minimum PaO2 values (deltaPaO2, 17+/-6 mm Hg during N2O washout and 6+/-3 mm Hg during xenon washout). The PaCO2 value also decreased (from 39.3+/-6.3 mm Hg to 37.6+/-5.8 mm Hg) during N2O washout (P<0.01) and during xenon elimination (from 35.4+/-1.6 mm Hg to 34.9+/-1.6 mm Hg; P< 0.01). The deltaPaCO2 was 1.7+/-0.9 mm Hg in the N2O group and 0.5+/-0.3 mm Hg in the xenon group (P<0.01). CONCLUSION: Diffusive hypoxia is unlikely to occur during recovery from xenon anesthesia, probably because of the low blood solubility of this gas.

Anesthetics, Inhalation↗