comparison LMA intub in obese

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Comparison between intubation and the laryngeal mask

airway in moderately obese adultsM. ZOREMBA, H. AUST, L. EBERHART, S. BRAUNECKER and H. W ULF Department of Anaesthesia, University of Marburg, Marburg, Germany

Background: Obesity is a well-established risk factor forperioperative pulmonary complications. Anaestheticdrugs and the effect of obesity on respiratory mechanicsare responsible for these pathophysiological changes, buttracheal intubation with muscle relaxation may also con-tribute. This study evaluates the inuence of airway man-agement, i.e. intubation vs. laryngeal mask airway (LMA),on postoperative lung volumes and arterial oxygen satura-tion in the early postoperative period.Methods: We prospectively studied 134 moderately obesepatients (BMI 30) undergoing minor peripheral surgery.They were randomly assigned to orotracheal intubation orLMA during general anaesthesia with mechanical ventila-tion. Premedication, general anaesthesia and respiratorysettings were standardized. While breathing air, we mea-sured arterial oxygen saturation by pulse oximetry. In-spiratory and expiratory lung function was measuredpreoperatively (baseline) and at 10 min, 0.5, 2 and 24 h

after extubation, with the patient supine, in a 30 1 head-upposition. The two groups were compared using repeated-measure analysis of variance (ANOVA) and t-test analysis.Statistical signicance was considered to be P o 0.05.Results: Postoperative pulmonary mechanical functionwas signicantly reduced in both groups compared withpreoperative values. However, within the rst 24 h, lungfunction tests and oxygen saturation were signicantly better in the LMA group ( P o 0.001; ANOVA).Conclusions: In moderately obese patients undergoingminor surgery, use of the LMA may be preferable toorotracheal intubation with respect to postoperative sa-turation and lung function.

Accepted for publication 12 November 2008

r 2009 The Authors Journal compilationr 2009 The Acta Anaesthesiologica Scandinavica Foundation

G ENERAL anaesthesia exerts several negativeeffects on lung function. 1,2 Relaxation andmechanical ventilation lead to an increased Va/Qmismatch, 3 and up to 90% of healthy adult patientsdevelop a measurable amount of atelectasis. 4 Obe-sity increases the likelihood of atelectasis. 5 In-creased BMI correlates with loss of perioperativefunctional residual capacity (FRC), expiratory re-serve volume and total lung capacity, up to 50% of preoperative values. 6 These ndings suggest thatadverse respiratory events are signicantly more

frequent in the obese. Most of these events occur inthe post-anaesthesia care unit (PACU). 7

Despite a number of controversial studies, manyanaesthetists prefer the complete airway controlthat orotracheal intubation offers in the obese pa-tient. Positive end-expiratory pressure (PEEP) andvital capacity (VC) manoeuvres can easily be ap-plied to prevent atelectasis, although airway irrita-tion 8 and the effects of muscle relaxation 9 may bedisadvantageous. In contrast, the laryngeal mask

airway (LMA) does not interfere with the larynx orthe normal expiratory laryngeal resistance, andmuscle relaxation is unnecessary. Normal diaphrag-matic tonicity is thus maintained and may help toprevent lung collapse. 10,11 The aim of our study wasto evaluate the impact of the operative airwaymanagement (LMA vs. orotracheal intubation) onearly postoperative lung function tests and pulseoximetry values in moderately obese adults.

MethodsStudy populationThe study was approved by the Ethics Committeeof the University of Marburg. Informed writtenconsent was obtained from each patient. We pro-spectively included 134 moderately obese adultpatients (BMI 3035, ASA IIIII) scheduled forminor peripheral surgery (Table 1). No operationsrequiring abdominal insufation (laparoscopy) orhead-down tilt were included. The minimum sur-

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Acta Anaesthesiol Scand 2009;53 : 436442Printed in Singapore. All rights reserved

r 2009 The Authors Journal compilation r 2009 The Acta Anaesthesiologica Scandinavica Foundation

ACTA ANAESTHESIOLOGICA SCANDINAVICA

doi: 10.1111/j.1399-6576.2008.01882.x


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gery time was set to be at least 40min up to 120 min.All patients were allocated on a random basis eitherto the intubation or to the laryngeal mask group(ProSeal

s

Laryngeal Mask LMA Group, Bonn,Germany). We excluded patients who had gastro-oesophageal reux disease or a hiatus hernia, air-way physical examination that may suggest the

presence of a difcult intubation, pregnancy,asthma requiring therapy, cardiac disease asso-ciated with dyspnoea 4 NYHA II or severe psy-chiatric disorders.

General anaesthesiaTwenty-four hours before surgery, patients werepremedicated with chlorazepat 20 mg per os. After

3 min of breathing 100% oxygen by face mask,anaesthesia was induced with fentanyl 23 m g/kgand propofol 2 mg/kg, followed by a continuousinfusion of propofol 510mg/kg/h. Subsequentdosages of remifentanil (0.10.2 m g/kg/min) andpropofol were adjusted according to haemody-namic variables and BIS values within a range

between 40 and 60 (BIS Quatrot

; Aspect MedicalSystems, Freising, Germany). To facilitate orotra-cheal intubation, a single dose of rocuronium(0.5mg/kg ideal body weight) was given; nofurther neuromuscular blocking agent was given.Patients were manually ventilated with 100% oxy-gen via a facemask. Respiratory settings were stan-dardized. Immediately after intubation orplacement of the laryngeal mask, the lungs weremechanically ventilated with a tidal volume of 8 ml/kg and the ventilation rate was adjusted tomaintain an end-tidal CO 2 pressure of approxi-

mately 44.7 kPa. A maximum peak pressure of 30cmH 2O (25 cmH 2O LMA) was set to be tolerable.The inspiration to expiration ratio was adjusted to1 : 1.5. A PEEP of 10 cmH2O was used in theintubation group. The cuff pressure was continu-ously adjusted to 30cmH 2O (LMA 50cmH 2O).Eighty percent oxygen in nitrogen was given dur-ing maintenance of anaesthesia. The peripheralarterial oxygen saturation was monitored continu-ously by pulse oximetry. The TOF ratio was con-trolled via a peripheral nerve stimulator, ensuring aTOF ratio 4 0.9012 before extubation. When the

patient was fully awake and breathing sponta-

Fig. 1. Postoperative pulse oximetry difference from preoperativebaseline. Changes within the study groups are signicant(Po 0.0001). For abbreviations, see text.

Fig.2. Postoperative expiratory lung function values difference from preoperative baseline. Changes within the study groups arsignicant (Po 0.001). For abbreviations, see text.

Intubation vs. laryngeal mask airway

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neously, the trachea was extubated, withoutprevious suction, in a head-up position, with apositive pressure of 10cmH 2O, using 100%O2 . Patients were transferred to the PACU, while breathing room air during transport. Theperipheral arterial oxygen saturation was continu-ously monitored by pulse oximetry. Each patientwas placed in the head-up position during thePACU stay.

Postoperative pain managementBoth groups received basic non-opoid analgesiawith intravenous (i.v.) paracetamol 1 g and meta-mizol 1 g i.v. Analgesia was supplemented withintermittent piritramide (i.v.) application when thevisual analogue scale (VAS) was 4 4.

Spirometry and pulse oximetrySpirometry and pulse oximetry were standardized,and the investigator was blinded, with each patientin a 301 head-up position 13 after breathing airwithout supplemental oxygen for 5 min. At thepre-anaesthetic visit, a baseline spirometry mea-surement and pulse oxymetry were taken (T0) aftera thorough demonstration of the correct technique.VC, forced vital capacity (FVC), forced expiratoryvolume in 1 s (FEV1) mid-expiratory ow (MEF25

75), peak expiratory ow (PEF), peak inspiratoryow and the forced inspiratory vital capacity weremeasured and the FEV1/FVC ratio was calculated.At each assessment, spirometry was performed atleast three times to be able to meet the criteria of theEuropean Respiratory Society, and the best mea-surement was recorded. 14 On arrival in the recoveryroom, at about 510min after extubation, we re-peated spirometry (T1) as soon as the patient wasalert and fully cooperative (Fast Track Score 4 10);15

pain and dyspnoea during coughing were assessedusing the Fast Track Score ( 4 10)15 before and, if necessary, after analgesic therapy. All patients metthis criterion within 20 min of extubation.

Spirometry and pulse oximetry assessmentswere repeated in the PACU at 0.5 h (T2), 2 h (T3)and 24 h (T4) after extubation. Before each mea-surement, all patients were free from pain duringcoughing and had a Fast Track Score 4 10. Overallpiritramide consumption was documented withinthe rst 24 postoperative hours. Factors that inter-fered with breathing (e.g. pain, shivering) were

Fig.3. Postoperative inspiratory lung function values difference from preoperative baseline. Changes within the study groups aresignicant (Po 0.01). For abbreviations, see text.

Table1Basic data for 134 patients undergoing elective minor peripheralsurgery.

Intubation(n 5 67)

Laryngeal mask(n 5 67)

Age (years) 53 (SD 12) 49 (SD 12)BMI 32 (SD 3.7) 30 (SD 3.2)Surgery time (min.) 81 (SD 21) 89 (SD 19)Postoperative pritramide(mg)consumption (within 24 h)

10 (SD 5.9) 11 (SD 6.3)

Knee arthroscopy n 5 16 n 5 12Minor breast surgery n 5 35 n 5 41TUR-prostata n 5 9 n 5 11Hand surgery n 5 7 n 5 3

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eliminated or at least minimized to produce reli-able measurements.

Statistical analysisWe tested the null hypothesis (H 0) that postoperativepulse oximetry values were comparable to preopera-tive values. The postoperative values were calcu-lated as a percentage of preoperative. To compare thestudy groups at each measurement point, we per-formed Students t-test with a type-I error of 5%(Table 3). We also performed a repeated-measureanalysis of variance within the study groups duringthe rst 24 postoperative hours (Figs 13). H 0 wasrejected at an adjusted P of o 0.0125 due to multipletesting. One hundred and thirty four patients wereincluded with four values each. The results were allanalysed using StatView 4.57 for Windows (AbacusSoftware, Heidelberg, Germany) and expressed asmean standard deviation (SD).

ResultsWe recruited 162 patients; the mean duration of surgery was 80 (SD 20) min, range 40120min.Acceptable ventilation was achieved in all, but vesubjects declined to continue with the protocol.Measurements were unsatisfactory in 16 (nine inthe LMA group, and seven in the intubation group),in whom the Fast Track Score was o 10 within20 min of surgery. Laryngo-/bronchospasm occurred

in four patients; three were in the intubation group(NS). Placement of the laryngeal mask was unsatis-factory in three patients, who were excluded fromthe study. Reversal of muscle relaxation was notnecessary in any patient. Thus, we present data for134 patients with 67 individuals per group (Table 1).

Pulse oximetryPreoperative saturations were within the normalrange and did not differ between the study groups(Table 2). In both groups, the lowest values werefound immediately after extubation in the PACU afterachieving a Fast Track Score 4 10. Oxygen saturationdecreased more in the intubation group at all stagesthan in the LMA group (Fig. 1, Table 3; Po 0.0001).

Spirometry measurementsPreoperative inspiratory and expiratory spirometricvalues were within the normal range (Table 2). Post-operatively, the LMA group fared signicantly better(Po 0.01) (Fig. 2, Table 3). However, throughout the T a

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measurement period, inspiratory and expiratory lungvolumes improved only moderately during the stayin the PACU. Even on the rst day after surgery, lungfunction was reduced by up to 25% of baseline, andinspiratory and expiratory lung volumes were sig-nicantly reduced ( Po 0.01; Fig. 2). Both study groupsshowed a similar recovery pattern over the course of the observation period. t-test analysis conrmed theadvantage of the LMA in the PACU at all measure-ment points (Table 3). The difference ceased to besignicant at 24 h post-surgery.

Postoperative managementNo patient suffered from untreatable postoperativepain. The maximum postoperative pain score on a

VAS scale before analgesia was 6 (both groups).Opioid consumption within 24 h was comparablein both groups (Table 2). At each measurementpoint, every patient was acceptably awake, andfree of pain, shivering or nausea.

DiscussionObesity has considerable negative effects on lungfunction in the perioperative period, due to a loss of FRC, atelectasis and increased desaturation. Mostpulmonary complications occur in the immediatepostoperative period, for which there are little data.Although healthy patients may easily compensatefor the postoperative impairment of lung function, in

Table3Postoperative pulse oximetry and lung function values.

Intubation Laryngeal mask P -value ( t -test)

SpO2 after surgery 90.3% (SD 2.8) 93.5% (SD 2.2) o 0.0001T 0.5 h 92.4% (SD 2.2) 94.7% (SD 2.1) o 0.0001T 2 h 93.6% (SD 2.3) 95.2% (SD 2.1) 0.0005T 24 h 95.0% (SD 1.8) 96.5% (SD 1.7) 0.0002FVC after surgery 2.33 l (SD 0.38) 2.62 l (SD 0.42) 0.0203T 0.5 h 2.50 l (SD 0.40) 2.78 l (SD 0.41) 0.0150T 2 h 2.62 l (SD 0.42) 2.93 l (SD 0.44) 0.0075T 24 h 2.91 l (SD 0.41) 3.37 l (SD 0.43) o 0.0001FEV1 after surgery 1.62 l (SD 0,27) 1.93 l (SD 0.36) 0.0010T 0.5 h 1.76 l (SD 0.33) 2.18 l (SD 0.37) 0.0015T 2 h 1.89 l (SD 0.36) 2.20 l (SD 0.37) 0.0016T24 h 2.25 l (SD 0.36) 2.58 l (SD 0.40) 0.0003PEF after surgery 2.83 l (SD 0.62) 3.74 l (SD 0.81) 0.0001T 0.5 h 2.98 l (SD 0.65) 3.91 l (SD 0.84) o 0.0001T 2 h 3.43 l (SD 0.72) 4.10 l (SD 0.85) 0.0033T24 h 4.84 l (SD 1.05) 5.24 l (SD 1.12) 0.1751(NS)MEF 25-75 after surgery 1.52 l (SD 0.33) 1.79 l (SD 0.35) 0.0028T 0.5 h 1.63 l (SD 0.40) 1.92 l (SD 0.40) 0.0033T 2 h 1.79 l (SD 0.48) 2.05 l (SD 0.43) 0.0072T 24 h 2.32 l (SD 0.51) 2.43 l (SD 0.51) 0.0950 (NS)MEF 75 after surgery 2.60 l (SD 0.62) 3.57 l (SD 0.89) o 0.0001T 0.5 h 2.73 l (SD 0.65) 3.71 l (SD 1.01 o 0.0001T2 h 3.16 l (SD 0.79) 3.84 l (SD 0.94) 0.0035T24 h 4.41 l (SD 1.05) 4.66 l (SD 1.10) 0.2327 (NS)MEF 50 after surgery 1.90 l (SD 0.45) 2.37 l (SD 0.56) 0.0082T 0.5 h 2.08 l (SD 0.56) 2.56 l (SD 0.66) 0.0133T 2 h 2.24 l (SD 0.60) 2.67 l (SD 0.64) 0.0275T 24 h 2.91 l (SD 0.75) 3.13 l (SD 0.65) 0.4180 (NS)MEF 25 after surgery 0.76 l (SD 0.18) 0.83 l (SD 0.17) 0.0182T 0.5 h 0.77 l (SD 0.19) 0.85 l (SD 0.18) 0.0009T2 h 0.83 l (SD 0.23) 0.91 l (SD 0.19) 0.0006T24 h 1.09 l (SD 0.25) 1.10 l (SD 0.19) 0.0076FIVC after surgery 2.14 l (SD 0.57) 2.35 l (SD 0.50) 0.0850T 0.5 h 2.26 l (SD 0.63) 2.60 l (SD 0.52) 0.0140T 2 h 2.37 l (SD 0.64) 2.77 l (SD 0.57) 0.0022T 24 h 3.03 l (SD 0.72) 3.25 l (SD 0.56) 0.1596 (NS)

PIF after surgery 1.57 l (SD 0.36) 1.71 l (SD 0.31) 0.0218T 0.5 h 1.73 l (SD 0.45) 1.99 l (SD 0.25) 0.0128T 2 h 1.89 l (SD 0.53) 2.10 l (SD 0.42) 0.0271T24 h 2.57 l (SD 0.71) 2.81 l (SD 0.61) 0.0065

P -value 5 t -test analysis for each measurement point tested on a signicance level of P o 0.05.For abbreviations, see text.

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the obese and those with pre-existing lung disease,postoperative lung volumes and oxygenation arelikely to be signicantly affected.

As reported previously 6,16 , the maximumchanges in spirometry and arterial saturation oc-curred during the rst assessment after extubation.Further measurements in the PACU showed only a

slight recovery of postoperative inspiratory andexpiratory lung functions within the rst 2 h. Weattribute this to impaired respiratory mechanics,obesity and atelectasis formation induced by gen-eral anaesthesia in the supine position.

Our data show that the use of an LMA duringminor peripheral surgery confers advantages formoderately obese adults in terms of early postopera-tive lung function and pulse oximetry saturation.Some anaesthetists may be reluctant to use the LMAin moderately obese adults; in our study, ventilationwas acceptable in all patients included, and previous

studies with sufcient power have conrmed this.17,18

Most of the problems in the LMA group were caused by inaccurate placement of the laryngeal mask withconsecutive leakage. Our ndings suggest that there isno difference in major adverse events (e.g. pulmonaryaspiration) between our study populations. No aspira-tion occurred during the study period in either group,although patients with increased risk were excluded.While there is no doubt that orotracheal intubation isthe gold standard for these cases, there are no data tosuggest that the use of the laryngeal mask to ventilatemoderately obese adults is associated with an in-

creased risk for pulmonary aspiration. There was nodifference in the incidence of laryngospasm betweenthe groups, although our study lacks the power todemonstrate such a difference.

Orotracheal intubation generates greater airwayirritation with subsequent tissue oedema, 8 whichcould mimic obstructive lung disease. It is uncer-tain whether this effect contributes to our ndingsto any signicant extent, because the surgical timedid not exceed 120min and the cuff pressure wascontinuously adjusted to 30 cmH 2O in the intuba-tion group and 50 cmH 2O in the LMA group.

Some patients receiving intraoperative musclerelaxants have a residual neuromuscular block afterextubation, which may affect the reliability of thestudy. To reduce this possibility, the minimum sur-gery time was 40 min and no additional dose of anymuscle relaxant was given, and extubation wasperformed only after recovery of the train-of-fourratio to 4 0.90.12 In view of our measured post-operative inspiratory lung volumes, which showeda similar postoperative recovery in both groups,

residual neuromuscular block can be almost entirelyexcluded. However, our data suggest that the initialmuscle relaxation to facilitate orotracheal intubationcauses a signicant amount of atelectasis. Previousstudies indicate that muscle relaxation develop at-electasis by compression of lung tissue rather than by resorption of gas. 9,10 This compression with con-

sequent small airway collapse persists up to 24hafter surgery, shown by a signicantly decreasedMEF25 in the intubation group, in spite of use of anintraoperative continuous PEEP of 10 cmH 2O Hg toprevent atelectasis. 1921 The decreases in VC, FVC,FEV1, MEF2575 and PEF followed the samepattern, and the FEV1/FVC ratio did not change.This suggests a restrictive pattern of respiratorycompromise in the immediate postoperative period,as described previously. 16,2225

The postoperative impairment of spirometrymeasurements was probably not caused by a lack

of cooperation, because all the patients in this studywere alert and fully compliant within 20 min of extubation, and any pain had been treated. Anylack of cooperation and insufcient pain manage-ment 6,16,22 would be expected to affect the wholestudy population to a comparable degree. Never-theless, our pulse oximetry and spirometry ndingsindicate that airway management has a greaterimpact on postoperative lung volumes than pre-viously assumed. The decreased inspiratory capa-city might affect the ability to cough effectively, andthus predispose to respiratory complications.

Our ndings suggest that moderately obesepatients who are scheduled for minor peripheralsurgery may benet from use of the laryngeal maskrather than orotracheal intubation. It is not clearwhether this is related to the initial muscle relaxa-tion to facilitate orotracheal intubation, or a speciceffect of the LMA. It is also unclear whether thisform of airway management reduces postoperativecomplications; larger studies are needed.

LimitationsOne major limitation factor is the preselection of ourpatients. Only moderately obese patients scheduledfor minor peripheral surgery were included. Nooperations with abdominal insufations (laparo-scopy) or head-down tilt were included. In addition,we excluded patients with gastro-oesophageal reuxdisease or a hiatus hernia. Furthermore, the potentialfor a selection bias was minimized by the support of anesthetists not involved in the study, who were


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responsible for giving patients preoperative informa-tion. Additionally, postoperative spirometry was per-formed by trained nurses who were unaware of thestudy hypothesis and were not involved in this study.

Our ndings do not allow us to suggest that theLMA should be used routinely for these cases. Theprimary aim of our study was to examine the

potential of different airway regimes for modifyingspirometrically measured lung volumes in the im-mediate postoperative period, when the impacts of surgical trauma and anaesthesia are most likely totrigger postoperative pulmonary morbidity. Thereduction of postoperative lung function was sig-nicantly greater in the intubation group than inthe LMA group. We conclude that the LMA may beconsidered as an alternative to orotracheal intuba-tion for moderately obese patients undergoingminor surgery. A larger study population is re-quired, however, in order to establish the LMA as

the standard procedure for our study population.

References1. Marshall BE, Wyche Jr. MQ Hypoxemia during and after

anesthesia. Anesthesiology1972; 37: 178209.2. Moller JT, Johannessen NW, Berg H, Esperesen K, Larsen

LE. Hypoxaemia during anaesthesia: an observer study. Br J Anaesth1991; 66: 43744.

3. Lundquist H, Hedenstierna G, Strandberg A, Tokics L,Bismar B. CT assessment of dependent lung densities inman during general anaesthesia. Acta Radiol1995; 36: 62632.

4. Gunnarsson L, Tokics L, Gustavsson H, Hedenstierna G.

Inuence of age on atelectasis formation and gas exchangeimpairment during general anesthesia. Br J Anaesth 1991;66: 42332.

5. Eichenberger A, Proietti S, Wicky S, Frascarolo P, Suter M,Spahn DR, Magnusson L. Morbid obesity and postopera-tive pulmonary atelectasis: an underestimated problem. Anesth Analg2002; 95: 178892.

6. Von Ungern-Sternberg BS, Regli A, Schneider MC, Kunz F,Reber A. Effect of obesity and site of surgery on periopera-tive lung volumes. Br J Anaesth2004; 92: 2027.

7. Benoit Z, Wicky S, Fischer JF, Frascarolo P, Chapuis C,Spahn DR, Magnusson L. The effect of increased FIO 2 before tracheal extubation on postoperative atelectasis. Anesth Analg2002; 95: 177781.

8. Kim E, Bishop MJ. Endotracheal intubation, but not lar-

yngeal mask airway insertion, produces reversible bronch-oconstriction. Anaesthesiology1999; 90: 3914.

9. Tokics L, Hedenstierna G, Strandberg A, Brismar B, Lund-quist H. Lung collapse and gas exchange during generalanesthesia: effects of spontaneous breathing, muscle pa-ralysis, and positive end-expiratory pressure. Anesthesiol-ogy 1987; 66: 15767.

10. Brismar B, Hedenstierna G, Lundquist H, Strandberg A,Svensson L, Tokics L. Pulmonary densities during anaes-thesia with muscular relaxation a proposal of atelectasis. Anaesthesiology1985; 62: 4228.

11. Pelosi P, Ravagnan I, Giurati G, Panigada M, Bottino N,Tredici S, Eccher G, Gattinoni L. Positive end-expiratorypressure improves respiratory function in obese but not innormal subjects during anesthesia and paralysis. Anesthe-siology1999; 91: 122131.

12. Eikermann M, Groeben H, Hu sing J, Peters J. Accelerome-try of adductor pollicis muscle predicts recovery of respira-tory function from neuromuscular blockade. Anesthesiology2003; 98: 13337.

13. Gudmundson G, Cerveny M, Shasby DM. Spirometricvalues in obese individuals, effect on body position. Am J Respir Crit Care Med1997; 155: 9989.

14. Standardized lung function testing. Offcial statement of theEuropean Respiratory Society. Eur Respir J 1993;16 (Suppl.):1100.

15. White PF, Song D. New criteria for fast-tracking afteroutpatient anesthesia: a comparison with the modiedAldretes scoring system. Anesth Analg 1999; 88: 106972.

16. von Ungern-Sternberg BS, Regli A, Reber A, Schneider MC.Comparison of perioperative spirometric data followingspinal or general anaesthesia in normal-weight and over-weight gynaecological patients. Acta Anaesthesiol Scand2005; 49: 9408.

17. Verghese C, Brimacombe JR. Survey of laryngeal mask

airway usage in 11,910 patients: safety and efciacy forconventional and nonconventional usage. Anaesth Analg1996; 82: 12933.

18. Voyagis GS, Photakis D, Kellari A, Kostani E, Kaklis S,Secha-Dousaitou PN, Tsakiropoulou-Alexiou H. The laryn-geal mask airway: a surwey of its usage in 1,096 patients. Minerva Anestesiol1996; 62: 27780.

19. Brismar B, Hedenstierna G, Lundquist H, Strandberg A,Svensson L, Tokics L. Pulmonary densities during anesthe-sia with muscular relaxation- aproposal of atelectasis. Anesthesiology1985; 62: 4228.

20. Tokics L, Hedenstierna G, Strandberg A, Brismar B, Lund-quist H. Lung collapse and gas exchange during generalanesthesia: effects of spontaneous breathing, muscle pa-ralysis, and positive end-expiratory pressure. Anesthesiol-

ogy 1987; 66: 15767.21. Coussa M, Proietti S, Schnyder P, Frascarolo P, Suter M,Spahn DR, Magnusson L. Prevention of atelectasis forma-tion during the induction of general anesthesia in morbidlyobese patients. Anesth Analg 2004; 98: 14915.

22. von Ungern-Sternberg BS, Regli A, Bucher E, Reber A,Schneider MC. The effect of epidural analgesia in labour onmaternal respiratory function. Anaesthesia 2004; 59: 3503.

23. Meyers JR, Lembeck L, OKane H, Baue AE. Changes infunctional residual capacity of the lung after operation. Arch Surg 1975; 110: 57682.

24. Alexander JL, Spence AA, Parikh RK, Stuart B. The role of airway closure in postoperative hypoxemia. Br J Anaesth1973; 5: 3440.

25. Craig D. Postoperative recovery of pulmonary function.

Anesth Analg1981; 60: 4652.

Address: Martin ZorembaDepartment of AnaesthesiaUniversity of MarburgBaldingerstraeD-35033 MarburgGermanye-mail: [email protected]

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