Publisher's copy made available with the permission of the publisher © Australian Society of AnaesthetistsThe aim of this study, during one-lung ventilation, was to evaluate if oxygenation could be improved by use of a simple oxygen reservoir or application of 5 cmH2O continuous positive airway pressure (CPAP) to the non-ventilated lung compared with an open airway. Twenty-three patients with lung malignancy, undergoing thoracotomy requiring at least 60 minutes of one-lung ventilation before lung lobe excision, were studied. After routine induction and establishment of one-lung ventilation, the three treatments were applied in turn to the same patient in a sequence selected randomly. The first treatment was repeated as a fourth treatment and these results of the repeated treatment averaged to minimize the effect of slow changes. Arterial oxygenation was measured by an arterial blood gas 15 minutes after the application of each treatment. Twenty patients completed the study. Mean PaO2 (in mmHg) was 210.3 (SD 105.5) in the 'OPEN' treatment, 186.0 (SD 109.2) in the 'RESERVOIR' treatment, and 240.5 (SD 116.0) in the 'CPAP' treatment. This overall difference was not quite significant (P=0.058, paired ANOVA), but comparison of the pairs showed that there was a significant better oxygenation only with the CPAP compared to the reservoir treatments (t=2.52, P=0.021). While the effect on the surgical field was not apparent in most patients, in one patient surgery was impeded during CPAP. Our results show that the use of a reservoir does not give oxygenation better than an open tube, and is less effective than the use of CPAP 5 cmH2O on the non-ventilated lung during one-lung ventilation.J. Slimani, W. J. Russell, C. Jurisevichttp://www.aaic.net.au/Article.asp?D=200404

Benumof J.L.

Capan L.M.

Chui P.T.

Cohen E.

Hogue C.W.

Ishikawa S.

Kamath B.S.

Orme R.M.

Patel M.

Pavlik M.

Pfitzner J.

Rees D.I.

Russell W.J.

Watanabe S.

Wilkes A.R.

Anaesthesia and Intensive Care

English

Slimani, J.

Russell, W.

Jurisevic, C.

Adelaide Research & Scholarship

Anaesthesia and Intensive Care, Vol. 32, No. 6, December 2004Anaesth Intensive Care 2004; 32: 756-760An Evaluation of the Relative Efficacy of an Open Airway,an Oxygen Reservoir and Continuous Positive AirwayPressure 5 cmH2O on the Non-ventilated LungJ. SLIMANI*, W. J. RUSSELL†, C. JURISEVIC‡Department of Anaesthesia & Intensive Care, Royal Adelaide Hospital and University of Adelaide and Cardiothoracic SurgicalUnit, Royal Adelaide Hospital, Adelaide, South AustraliaSUMMARYThe aim of this study, during one-lung ventilation, was to evaluate if oxygenation could be improved by use of a simpleoxygen reservoir or application of 5 cmH2O continuous positive airway pressure (CPAP) to the non-ventilated lungcompared with an open airway. Twenty-three patients with lung malignancy, undergoing thoracotomy requiring at least 60 minutes of one-lung ventilation before lung lobe excision, were studied. After routine induction andestablishment of one-lung ventilation, the three treatments were applied in turn to the same patient in a sequenceselected randomly. The first treatment was repeated as a fourth treatment and these results of the repeated treatmentaveraged to minimize the effect of slow changes.Arterial oxygenation was measured by an arterial blood gas 15 minutes after the application of each treatment.Twenty patients completed the study. Mean PaO2 (in mmHg) was 210.3 (SD 105.5) in the “OPEN” treatment, 186.0(SD 109.2) in the “RESERVOIR” treatment, and 240.5 (SD 116.0) in the “CPAP” treatment. This overall differencewas not quite significant (P=0.058, paired ANOVA), but comparison of the pairs showed that there was a significantbetter oxygenation only with the CPAP compared to the reservoir treatments (t=2.52, P=0.021). While the effect onthe surgical field was not apparent in most patients, in one patient surgery was impeded during CPAP. Our resultsshow that the use of a reservoir does not give oxygenation better than an open tube, and is less effective than the useof CPAP 5 cmH2O on the non-ventilated lung during one-lung ventilation. Key Words: ONE-LUNG ANAESTHESIA, ONE-LUNG VENTILATION: arterial oxygenation, oxygen reservoir, CPAPOne-lung ventilation is frequently associated withimpaired pulmonary oxygen exchange. This is ex-plained by a large ventilation-perfusion mismatchwhich is aggravated by the lateral decubitus position,surgery (open chest), anaesthesia and paralysis.Some patients poorly tolerate the resultinghypoxaemia. In order to improve patient oxygenation,the following techniques are used commonly1,2: — Application of a continuous positive airways pres-sure (CPAP) of 5 cmH2O, CPAP 10 cmH2O to the non-dependent lung, and/or positive end-expiratory pressure (PEEP) of 5 cmH2O, PEEP 10 cmH2O to the dependent ventilated lung3.CPAP, however, may impair surgical access,particularly if it is high. — Insufflation of oxygen at 7 l/min with or without acombination of the above4,5. — High-frequency jet ventilation6.One study described the use of an oxygen reservoirto improve oxygenation. However, this technique wasnot evaluated against other methods7. Most of thesystems described so far to provide CPAP are com-plex and vary from one institution to another8. Thecommercial system to apply CPAP to the non-depen-dent, non-ventilated lung (Mallinckrodt Inc. St.Louis, Missouri, U.S.A.) is expensive and may not beavailable in every institution. The CPAP may alsosometimes make surgery on the non-ventilated lungmore difficult. This study compares the effect of a simple oxygenreservoir (easy to assemble and inexpensive), CPAP 5 cmH2O, and an open tube on the non-ventilatedlung, on the arterial oxygenation and also its effect onthe surgical field.*M.D., Provisional Fellow.†M.B.B.S., F.R.C.A., F.A.N.Z.C.A., Ph.D., D.I.C., Clinical Professor,Director Research & Development.‡M.B.B.S., M.S., F.R.A.C.S., Visiting Thoracic Surgeon.Address for reprints: Prof W. J. Russell, Department of Anaesthesia andIntensive Care, Royal Adelaide Hospital, North Terrace, Adelaide, S.A.5000.Accepted for publication on July 22, 2004.The oxygen reservoir consists of an anaestheticfilter (Ultipor BB25, Pall Medical Corporation,Newquay, Cornwall, U.K.) connected to the non-ventilated lung with an oxygen source deliveringoxygen at 6 l/min, via the sampling line port (theproximal connection to the anaesthetic circuit beingleft open to air). The aim of the reservoir is to preventinspiratory movement, such as might be caused bymediastinal shift, from entraining air into the non-ventilated lung.Breathing system filters have already been used asoxygen delivery devices with the laryngeal mask9 andwith the endotracheal tube during recovery10.The minimum inspired O2 delivered by the breath-ing system filters at a flow of 6 l/min to 8 l/min withthese systems is about 50% to 60% for a tidal volumeof 500 ml and a respiratory rate of 10 per minute11.For lower tidal volumes, the percentage of oxygenfrom the reservoir will be greater and if the inspira-tory flow is not greater than 6 l/min (100 ml/s), closeto 100%. The tidal volume in the unventilated lungcaused by the mediastinal shift should be small andthus the inspired oxygen high.METHODSThe Ethics Committee of the Royal AdelaideHospital approved the study. Informed consent wasobtained from each patient. Adult patients with carci-noma of the lung who were undergoing elective openthoracotomy including frozen section biopsy with anexpected duration of one-lung ventilation of at leastsixty minutes before lung resection were studied. After routine induction and insertion of an intra-arterial cannula, the patients were intubated with aleft double-lumen tube and positioned for surgery.The left double-lumen tube was selected as deter-mined by the size of the left main bronchus on a stan-dard chest X-ray12. It was inserted with bronchialocclusion and checked by isolation of each lungdemonstrating selective ventilation, and ausculta-tion13. Anaesthesia was maintained with isoflurane inoxygen (inspired O2 100%) and muscle relaxant asrequired. All patients had a thoracic epidural insertedand a metaraminol infusion was used to maintainblood pressure above a systolic pressure of 100 mmHg.An initial blood gas on two-lung ventilation wastaken. Once one-lung ventilation was established,patients were ventilated with a tidal volume of 5 mlper kg with the respiratory rate adjusted to keep the PaCO2 between 35 to 45 mmHg. Variations ofarterial oxygenation due to haemodynamic changeswere kept to a minimum by the use of adequateanalgesia and the use of the vasopressor infusion as required. No suctioning of either lung was performed during the one-hour duration of the study.One of the following six treatment sequences (asselected from a table of random numbers) wasapplied to the lumen of the non-ventilated lung foreach subject.1. Open, CPAP5, O2 reservoir, Open2. Open, O2 reservoir, CPAP5, Open3. O2 reservoir, Open, CPAP5, O2 reservoir4. O2 reservoir, CPAP5, Open, O2 reservoir5. CPAP5, O2 reservoir, Open, CPAP56. CPAP5, Open, O2 reservoir, CPAP5.Details of the treatments were as follows:— Open: the 15 mm conical connection end ofdouble lumen tube was left open to air— CPAP: 5 cmH2O of CPAP was applied to the non-ventilated lung with oxygen flowing at 2 litres perminute to a “T” piece with a CPAP valve (LaerdalCorp.) set at 5 cmH2O— O2 reservoir (Ultipor BB25 filter with a deadspace of 35 ml with oxygen connection to gassampling port) oxygen flowing at 6 litres perminute.Each treatment in the sequence was applied for aperiod of fifteen minutes. This stabilization period isrequired before oxygen delivery is reassessed14. At theend of each period, a blood gas was taken and the sur-geon, who was blinded to the sequence, was askedabout any effects on the surgical field. The study was continued during the examination of the lung biopsies for immediate frozen sectionhistology and for the initial dissection of the lung. If a pneumonectomy or lobectomy were to be per-formed, the study was completed before ligation ofthe bronchial vessels.Criteria for terminating the study were:— An arterial saturation less than 90% pre-operatively.— An arterial saturation less than 85% with any ofthe treatment sequences.— Unsatisfactory surgical conditions.Data analysisThe data are shown in Figure 1. For each sequence,the initial treatment was repeated as the final treat-ment of the study. Statistical comparisons were per-formed using Student’s test or repeated measureANOVA (see below), with P<0.05 considered asstatistically significant.RESULTSTwenty-three patients were studied. Three patientswere removed from analysis because the fullsequence was not completed (Table 1): two patients757OPEN AIRWAY, OXYGGEN RESERVOIR AND CPAP IN ONE-LUNG VENTILATIONAnaesthesia and Intensive Care, Vol. 32, No. 6, December 2004because of the need to re-expand the lung for surgicalreasons. The application of CPAP 5 cmH2O in theother patient made the surgical dissection toodifficult and so the study was abandoned.The results were analysed on the 20 patients whocompleted the study. The allocation of the treatmentsequences is given in Table 2.Examination of the initial and final PaO2 (inmmHg) regardless of treatment, was mean 324.1 (SD 159.0) and 189.4 (SD 104.7), (SD difference171.3) P=0.0023 (paired t two-sided). Therefore thePaO2 estimate used for the initial treatment mode oneach patient was the average between the first and758 J. SLIMANI, W. J. RUSSELL, C. JURISEVICAnaesthesia and Intensive Care, Vol. 32, No. 6, December 2004FIGURE 1: PaO2 in mmHg during the use of an open tube (clear columns), an oxygen reservoir (shaded columns) and CPAP (continuousairway positive pressure 5 cmH2O, hatched columns) for each patient. Oxygenation varies markedly between patients. However, thechanges within each patient are not quite statistically significant (P=0.058). Paired comparison showed no difference between open andCPAP treatments, nor between open and reservoir treatments. A significantly better oxygenation occurred between CPAP and reservoirtreatments P=0.021.TABLE 1Patients excluded from the study: these were not included in thestatistical analysisPatients No. Comments4 (Seq. 3) Long standing empyema undergoing surgical lungdecortication. Two lung ventilation to re-expandright lung after 5 min CPAP 5.6 (Seq. 3) O2 reservoir done after 12 min: Two lung ventila-tion requested by surgeon for 3 min.ABG on CPAP5 and O2 reservoir not done due tooperation shorter than anticipated.Left lung collapsed due to long standing pleuraleffusion.14 (Seq. 1) Lung inflation. CPAP 5 abandoned after 3 min atsurgeon’s request due to increase difficulty withdissection. TABLE 2Number of patients in each treatment sequenceSequences Number of patients1. Open, CPAP 5, O2 reservoir, Open 32. Open, O2 reservoir, CPAP 5, Open 33. O2 reservoir, Open, CPAP 5, O2 reservoir 54. O2 reservoir, CPAP 5, Open, O2 reservoir 15. CPAP 5, O2 reservoir, Open, CPAP 5 46. CPAP 5, Open, O2 reservoir, CPAP 5 4CPAP 5 (continuous airway positive pressure 5 cmH2O).the last treatments to derive an estimate independentof the progressive change with time.Mean PaO2 (in mmHg) in the “OPEN” group was210.3 (SD 105.5), 186.0 (SD 109.2) in the “RESER-VOIR” group, and 240.5 (SD 116.0) in the “CPAP”group. Statistical analysis using repeat measures ANOVAshowed that the difference between the threemethods studied is not quite significant (RepeatMeasures F=3.07, P=0.058). However, furtheranalysis of the treatment as pairs showed: comparisonbetween open and reservoir treatments, t=1.154P=0.263, comparison between open and CPAPtreatments, t=1.30 P=0.210 and comparison betweenreservoir and CPAP treatments, t=2.52 P=0.021.Thus the reservoir treatment is significantly worsethan the CPAP 5 cmH2O treatment.Surgical assessmentIn twenty of the twenty-three patients studied, theoperating conditions were not impaired by the appli-cations of the treatments. Inflation and partial infla-tion of the lung was noticed by the surgeon in twocases during application of CPAP, while in anothercase continuous positive pressure had to be aban-doned due to increased difficulty with dissection. Thisinterference with the surgical field is consistent withthe findings of previous studies on CPAP15.For the oxygen reservoir, partial inflation of thelung was noticed by the surgeon only in two cases butdid not cause any surgical difficulty. No inflation wasobserved in any case with the open tube.DISCUSSIONOur study aimed to examine if the simple oxygenreservoir, compared with CPAP 5 cmH2O and thedouble-lumen tube left open to air, would result in animprovement of arterial oxygenation without inter-fering with the surgical field. In the 20 patients, whilstthe application of the oxygen reservoir did not inter-fere with the surgical field, the oxygen reservoir wasinferior to CPAP 5 cmH2O at a marginal statisticallevel allowing for a Bonferroni correction of 2.5. Theopen tube and the reservoir achieved a similar levelof arterial oxygenation.Factors directly related to the surgery, the anaes-thetic and the nature of the pulmonary and pleuralpathology influence the results of a one-lung study.The surgical compression of the lung16 and the clamp-ing of pulmonary vessels (in particular clamping ofthe pulmonary artery) are known to cause variation inthe arterial oxygenation during one lung ventilation17.For this reason our study was done before clampingof any pulmonary arteries or veins.The oxygenation of the patient is affected also bythe duration of one lung ventilation, being the lowestat about 27 minutes with a peak at about 1 hour and25 minutes18. To minimize the impact of this intra-operative variation in oxygenation19, we used the sixpossible sequences for the three treatments in arandom order. The duplication of the first treatmentat the end as a fourth was to compensate for any slowchanges that occurred.Although we tried to maintain the parameters ofventilation constant during the study, we had toadjust the respiratory rate to maintain the PaCO2 inthe normal range in some cases.For maximum improvement in oxygenation, con-tinuous positive pressure is usually applied with priorinflation of the lung. We deliberately used a low levelof continuous positive pressure (5 cmH2O) appliedwithout prior inflation in order not to interfere withthe surgical field. This may explain why the improve-ment in oxygenation with CPAP was minimal in ourstudy. The primary condition of the patient representsone of the major factors determining the arterial oxy-genation during one-lung ventilation. This can beseen in Figure 1 where each patient tends to havesimilar PaO2 values for each treatment but the oxy-genation between patients varies markedly. Our studyshows that oxygenation with an oxygen reservoir isnot more effective than an open airway, but CPAP 5 cm of H2O can achieve some benefit. It may be thata higher CPAP could have achieved a significantlybetter oxygenation. However, higher CPAP may evenmore impede the surgical exposure.ACKNOWLEDGEMENTSWe would like to thank the staff of the Cardio-thoracic Surgical Unit at the Royal Adelaide Hospitalfor their cooperation during this study. We also thankDr L. McEwin, consultant anaesthetist, for hersupport and advice. REFERENCES1. Benumof JL. One-Lung ventilation and hypoxic pulmonaryvasoconstriction: Implications for anesthetic management.Anesth Analg 1985; 64:821-833.  2. Cohen E. Management of one lung ventilation. AnesthesiolClin Nth Am 2001; Vol 19.3. Cohen E, Eisenkraft JB. Positive end-expiratory pressureduring one-lung ventilation improves oxygenation in patientswith low arterial oxygen tensions. J Cardiothorac Vasc Anesth1996; 10:578-582.4. Capan LM, Turndorf H, Chandrakant P, Ramanathan S,Acinapura A, Chalon J. Optimisation of arterial oxygenationduring one-lung anesthesia. Anesth Analg 1980; 59:847-851. 5. Rees DI, Wansbrough SR. One-lung anesthesia: Percent shuntand arterial oxygen tension during continuous insufflation of759OPEN AIRWAY, OXYGGEN RESERVOIR AND CPAP IN ONE-LUNG VENTILATIONAnaesthesia and Intensive Care, Vol. 32, No. 6, December 2004760 J. SLIMANI, W. J. RUSSELL, C. JURISEVICAnaesthesia and Intensive Care, Vol. 32, No. 6, December 2004oxygen to the non-ventilated lung. Anesth Analg 1982; 61:507-512.6. Kamath BS, Abdelatti MO, Mestre X. Management ofhypoxaemia during one-lung anaesthesia: a suggestion. Anaes-thesia 1998; 53:414-415.7. Pfitzner J, Peacock MJ, Daniels BW. Ambient pressure oxygenreservoir apparatus for use during one lung anaesthesia.Anaesthesia 1999; 54:454-458.8. Hogue CW Jr. Effectiveness of low levels of non-ventilatedlung continuous positive airway pressure in improving arterialoxygenation during one lung ventilation. Anesth Analg 1994;79:364-367.  9. Orme RM, Williams M. Supplementary oxygen and the laryn-geal mask airway—Evaluation of a heat-and-moisture ex-changer. Anaesth Intensive Care 1999; 27:509-511.10. Chui PT, Poon M. Using the Pall HME filter as an oxygentherapy device in recovery room. Anaesth Intensive Care 1996;24:514.11. Wilkes AR, Vaughan RS. The use of breathing system filters asoxygen-delivery devices. Anaesthesia 1999; 54:552-558.12. Russell WJ, Strong TS. Dimensions of double-lumen tracheo-bronchial tubes. Anaesth Intensive Care 2003; 31:50-53.13. Russell WJ. A blind guided technique for placing double-lumen endobronchial tubes. Anaesth Intensive Care 1992;20:71-74.14. Patel M, Singer M. The optimal time for measuring thecardiorespiratory effects of positive end expiratory pressure.Chest 1993; 104:327-332.15. Pavlik M, Ctvrteckova D, Zvonicek V, Sevcik P, Capov I,Jedlicka V. The improvement of arterial oxygenation duringone-lung ventilation: effect of different CPAP levels. Acta ChirHung 1999; 38:103-105.16. Ishikawa S, Nakazawa K, Makita K. Progressive changes inarterial oxygenation during one-lung anaesthesia are related tothe response to compression of the non-dependent lung. Br JAnaesth 2003; 90:21-26.  17. Benumof JL. Conventional and differential lung managementof one lung decrease ventilation, Anesthesia for ThoracicSurgery 2nd Ed. Philadelphia, Saunders. 1995:406-431.18. Ishikawa S. Oxygenation may improve with time during onelung ventilation. Anesth Analg 1999; 89:258-259.19. Watanabe S, Noguchi E, Yamada S, Hamada N, Kano T.Sequential changes of arterial oxygen tension in the supineposition during one-lung ventilation. Anesth Analg 2000;90:28-34.

A blind guided technique for placing doublelumen endobronchial tubes. Anaesth Intensive Care

Ambient pressure oxygen reservoir apparatus for use during one lung anaesthesia. Anaesthesia

Conventional and differential lung management of one lung decrease ventilation, Anesthesia for Thoracic Surgery 2nd Ed.

Dimensions of double-lumen tracheobronchial tubes. Anaesth Intensive Care

Effectiveness of low levels of non-ventilated lung continuous positive airway pressure in improving arterial oxygenation during one lung ventilation. Anesth Analg

Management of hypoxaemia during one-lung anaesthesia: a suggestion. Anaesthesia

Management of one lung ventilation.

One-lung anesthesia: Percent shunt and arterial oxygen tension during continuous insufflation of 759

One-Lung ventilation and hypoxic pulmonary vasoconstriction: Implications for anesthetic management. Anesth Analg

Optimisation of arterial oxygenation during one-lung anesthesia. Anesth Analg

Oxygenation may improve with time during one lung ventilation. Anesth Analg

Positive end-expiratory pressure during one-lung ventilation improves oxygenation in patients with low arterial oxygen tensions.

Progressive changes in arterial oxygenation during one-lung anaesthesia are related to the response to compression of the non-dependent lung.

Sequential changes of arterial oxygen tension in the supine position during one-lung ventilation. Anesth Analg

Supplementary oxygen and the laryngeal mask airway—Evaluation of a heat-and-moisture exchanger. Anaesth Intensive Care

The improvement of arterial oxygenation during one-lung ventilation: effect of different CPAP levels. Acta Chir Hung

The optimal time for measuring the cardiorespiratory effects of positive end expiratory pressure. Chest

The use of breathing system filters as oxygen-delivery devices. Anaesthesia

Using the Pall HME filter as an oxygen therapy device in recovery room. Anaesth Intensive Care

An evaluation of the relative efficacy of an open airway, an oxygen reservoir and continuous positive airway pressure 5 cmH2O on the non-ventilated lung

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An Evaluation of the Relative Efficacy of an Open Airway, an Oxygen Reservoir and Continuous Positive Airway Pressure 5 cmH
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An evaluation of the relative efficacy of an open airway, an oxygen reservoir and continuous positive airway pressure 5 cmH2O on the non-ventilated lung

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