cavity was irrigated with 300 ml hydrogen peroxide. The fluid made a white foam as a reaction with perox- idase. A few seconds later the end-tidal CO 2 concen-.
338 reservoir bag is suddenly halved. If a compliance loop, such as is available on the Datex AS3 is in use, the point is seen as a sudden halving of the compliance. The other frequent sign is a noticeable resistance to further advancement as the inflated cuff is too large to enter the left main bronchus. Once the point of the bronchial cuff plugging the left main bronchus is identified, the correct position can be easily achieved. The bronchial cuff is completely deflated and the tube advanced a distance equal to the length of the bronchial cuff plus a further centimetre to place it just beyond the carina. The bronchial cuff is then inflated to obtain a seal in the usual way. The same technique can be used with a fight sided tube to place accurately a DLT with fight bronchial profiled cuffs such as on the Mallinckrodt tube. It cannot be effectively used with right double tubes using two small cuffs such as the Sheridan to span the right upper lobe bronchus because the small cuffs cannot be inflated sufficiently in the trachea to ventilate both lungs effectively This technique was originally reported in Anaesthesia and Intensive Care in 1992 (Russell WJ. A blind guided technique for placing double-lumen endobronchial tubes. Anaesth Intensive Care 1992; 20: 71-4) and a further explanatory letter was written on the techniques of detection in 1996 (Russell WJ. Further reflections on "A blind guided technique for endobronchial intubation" Anaesth Intensive Care 1996; 24: 123). With this technique, there is no need to use a fibreoptic bronchoscope to place or confirm the position if the left main bronchus has been clearly identified. W. John Russell VhD, FF~CS Adelaide, Australia REPLY We appreciate Russell's comments and interest in our recent letter. 1 Several methods and manoeuvres have been described in the literature for the placement of double lumen endobronchial tubes.2 Our method is a faster, practicable and simple way to decrease tube malposition, without changing the usual well-known technique. We regret that Russell's technique3,4 was not included in our references but it was not known to us at the time. We are glad to have the opportunity to spread the diffusion of his method.
Alftedo Panadero MO vhn, Mafia Jose Iribarren MD VhD, Ignacio Fernandez-Liesa MD, Pablo Monedero MD Pho University of Navarra Pamplona (Spain) REFERENCES
1 Panadero .4, Iribarren MJ, Fern~ndez-Liesa I, Monedero P. A simple m e t h o d to decrease malposition
of Robertshaw-type tubes (Letter). Can J Anaesth 1996; 43: 984.
CANADIAN JOURNAL OF ANAESTHESIA
2 BenumofJL, Alfery DD. Anesthesia for thoracic surgery. In: Miller RD (Ed.). Anesthesia. New York: Churchill Livingstone, 1994: 1689-715. 3 Russell W~. A blind guided technique for placing doublelumen endobronchial tubes. Anaesth Intensive Care 1992; 20: 71-4. 4 Russell WJ. Further reflections on "a blind guided technique for endobronchial intubation" (Letter). Anaesth Intensive Care 1996; 24: 123.
Pulmonary embolism and hydrogen
peroxide Pulmonary embolism during surgery is rare3 -s Recendy, we witnessed a case of an unexpected air embolism due to hydrogen peroxide. A 53-yr-old women tmderwent bilateral pulmonary lobectomy. Preoperative evaluation was unremarkable. Anaesthesia was with general and epidural anaesthesia. Arterial and central venous lines were placed and resection of the two lobes was uneventful with no ox3~genation problems. At the end of the procedure, the open hemithoracic cavity was irrigated with 300 ml hydrogen peroxide. The fluid made a white foam as a reaction with peroxidase. A few seconds later the end-tidal CO 2 concentration decreased by half (4.5 to 2.2%), accompanied by haemodynamic instability, decrease in the oxygen saturation and changes in the ST segment of the ECG. The CVP was not recorded during the event. Immediately, the patient was placed in a head-down position and rapid pharmacological intervention for hypotensior~ and ventricular tachycardia was successfully performed with 35 mg ephedrine and 100 mg lidocaine. Symptoms disappeared within two minutes. In this case, the timing of the symptoms with the use of irrigating fluid makes oxygen embolism very likely. H o w the gas was absorbed remains unclear, but most authors postulate that air entry occurs mainly in the surgical field. 1,4 In our case, the right hemithoracic cage was nearly completely open with the lower lobe still collapsed. When using hydrogen peroxide, administration into preformed body cavities should be avoided or made using only small volumes of peroxide. Christoph Konrad MD, Guido Schiipfer MD MBA HSG, Markus Wietlisbach MD, H. Gerber MD Institute of Anesthesiology Kantonsspital CH-6000 Lucerne 16 Switzerland
CORRESPONDENCE REFERENCES
1 Morikawa H, Mima H, Fujita I-I, Mishima S. Oxygen embolism due to hydrogen peroxide irrigation during cervical spinal surgery. Can J Anaesth 1995, 42: 231-3. 2 SaissyJM, Guignard B, Pats B, Lenoir B, Rouvier B. Risks of hydrogen peroxide irrigation in military surgery. (French) Ann Fr Anesth Reanim 1994; 13: 749-53. 3 Ferrari M, Catena S, Ferrari F, Bianchi R, Villani A. Severe pulmonary gas embolism caused by intraoperafive administration of hydrogen peroxide. (Italian) Minerva Anesthesiol 1994; 60: 403-6. 4 WilliamsonJ, WebbR, Russell W, Runciman W. The Australian Incident monitoring study. Air embolism an analysis of 2000 incident reports. Anaesth Intensive Care 1993; 21: 638-41.
Regional anaesthesia and reactive airway disease To the Editor: We read with interest the recent review article of LM Pinto Pereira et al. 1 and commend them for their remarkable synthesis on the "Physiological mechanisms, pathophysiological alterations and therapeutic considerations." However, in the first part of their paper dealing with "Perioperative management of the patient with reactive airways," we were very surprised not to find mention of regional anaesthetic techniques. All the anaesthetic recommendations were directed towards general anaesthesia. We would like to point out that a regional anaesthetic technique should be considered systematically in patients with reactive airways and usually preferred to general anaesthesia2,a although this does not always prevent intraoperative bronchospasm in asthmatic patients. 4 Frederic J. Mercier MD, Herve Bouaziz MD, Dan Benhamou MD Departement d'Anesthesie-Reanimation, H6pital Antoine Beclere 157 rue de la Porte de Trivaux, 92141 Clamart Cedex-France
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3 Kuwahara B, GoreskyGV. Anaesthetic management of an asthmatic child for appendicectomy. Can J Anaesth 1994; 41: 523-6. 4 MercierFJ, Benhamou D. Anaesthetic management in patients with asthma. Can J Anaesth 1996; 43: 195-6. REPLY Mercier et al. have raised the important consideration of regional anaesthesia in patients with hyperactive airways. Regional anaesthesia avoids the respiratory depression associated with general anaesthetic techniques, airway instrumentation and diminished airway reflexes. In pelvic, perineal and lower extremity surgery regional anaesthesia is associated with fewer respiratory complications and may be preferred to general anaesthesiaJ However, the associated respiratory complications (83%fl with high spinal anaesthesia and epidural block make regional anaesthesia unsuitable for upper abdominal surgery. Inhibition of sympathetic innervation may precipitate a sharp decrease in bloodpressure and severe bronchospasm in the asthmatic patient2 from the combination of neural blockade of the adrenal gland/ interference with pulmonary sympathetic innervation a and unopposed vagal activity. 2 Additionally, loss of expiratory muscle power may compromise the condition of patients with airway obstruction and who rely on active exhalation for adequate gas exchange,s The principle advantage of regional anaesthesia is continuous neurological evaluation which may be lost in patients who are not co-operative. Sedatives and analgesics in thesepatients may make respiratory compromise a distinct possibility. Our review aimed to describe the pathophysiology of the disease and provide updated information on current and new therapies in patients who receivegeneral anaesthesia. Drs. Mercier, Bouaziz and Benhamou have made a valuable comment which stressesthe importance ofpreoperative assessment and the application of regional over general anaesthesia when possible in the asthmatic patient. Les[ey M. Pinto Pereira MD Department of Para-Clinical Sciences University of the West Indies, St. Augustine Trinidad, West Indies REFERENCES
REFERENCES
1 Pinto Pereira LM, Orrett FA, Balbirsingh M. Physiological perspectives of therapy in bronchial hyperreactivity. Can J Anaesth 1996; 43: 700-13. 20lsson GL. Bronchospasm during anaesthesia. A computeraided incidence study of 136, 929 patients. Acta Anaesthesiol Scand 1987; 31: 244-52.
1 Gold MI, Hdrich M. A study of the complications related to anesthesia in asthmatic patients. Anesth Analg 1963; 42: 283-93. 2 Brown DT. Regional anaesthesia. In: Wildsmith JAW, Armitage EN (Eds.). Principles and Practice of Regional Anaesthesia. New York: Churchill Livingstone Inc., 1987: 8-14.
