Thorax 1993;48:381-384 381 Static lung volumes in healthy subjects assessed by helium dilution during occlusion of one mainstem bronchus Thorax: first published as 10.1136/thx.48.4.381 on 1 April 1993. Downloaded from B Johansen, 0 Bj0rtuft, J Boe Abstract preoperative assessment of patients with Background-Single lung function is bronchial carcinomas' and in the follow up usually assessed by radioisotopes or, after single lung transplantation.2 Broncho- more rarely, by bronchospirometry in spirometry, in which an intubated double which a double lumen catheter is used to lumen catheter separates flow in the two separate ventilation of the two lungs. The lungs, has previously been used for preopera- latter is more precise but less comfort- tive assessment.3 Distribution of ventilation, able. An alternative bronchoscopic lung volumes, and other common indices of method is described for determniiiing the single lung function can also be assessed by volume of a single lung. this technique. Methods-One mainstem bronchus was The procedure described here is a more temporarily occluded with an inflatable comfortable form of bronchospirometry. balloon during fibreoptic bronchoscopy During temporary occlusion of one mainstem in 12 healthy volunteers aged 18-29 years. bronchus by an inflatable balloon, standard The functional residual capacities (FRC) pulmonary function tests can be applied to of the right, left, and both lungs were the other lung. The balloon is positioned dur- measured in duplicate by closed circuit ing fibreoptic bronchoscopy after topical helium dilution. Supplementary vital anaesthesia. We have evaluated the method in capacity (VC) manoeuvres permitted healthy subjects and measured their static calculation of single lung capacities lung volumes separately for the right and left (TLC) and residual volumes (RV). lungs. Results-The standard deviation of a sin- http://thorax.bmj.com/ gle determination of capacities of the right, left, and both lungs were: TLC, 80, Methods 96, and 308 ml; VC, 56, 139, 171 ml; FRC, SUBJECTS 131, 74, and 287 ml; RV, 112, 185, and 303 Twelve healthy volunteers (eight men and ml, respectively. The sum of the right four women) aged 18-29 years, smokers and and left unilateral TLC was not different non-smokers, participated in the study. They from bilateral TLC (6-12 v 5 95 1) and the were recruited from staff members, relatives, sum of the unilateral FRC was not differ- and medical students and had no history of on September 30, 2021 by guest. Protected copyright. ent from the bilateral FRC (2-60 v 2*78 1). respiratory or cardiac disease. None had had The sum of the unilateral VC was lower any respiratory symptoms and their ventilatory than bilateral VC (4.52 v 4-80 1), that of lung function was within normal limits as the unilateral RV was higher than bilat- determined by dynamic spirometry on the eral RV (1.60 v 1-16 1). For all subdivi- day of the investigation.4 Two additional sub- sions of lung volume, the right lung was jects were excluded; one man who fainted larger than the left. The most common during bronchoscopy but before the balloon complaint was substernal discomfort was inflated, and a woman who cooperated during complete exhalation. Oxygen sat- well but during the measurements a leak was uration rarely fell below 90%. discovered in a spirometer hose. Conclusions-Temporary occlusion of a mainstem bronchus in normal subjects is TECHNICAL EQUIPMENT safe, relatively simple, and allows fairly Fogarty venous thrombectomy catheters (size precise and accurate measurements of 8/10 French), 80 cm in length, were used Department of unilateral static lung volumes. Occlusion with a maximum diameter of 19 mm with the Thoracic Medicine, at TLC, however, probably prevents balloon inflated and a balloon capacity of 4 Rikshospitalet, The National Hospital, proper emptying of the non-occluded ml (American Edwards Laboratories, Santa University of Oslo, lung. Ana, California, USA). The catheter was N-0027 Oslo, Norway advanced into the airways under guidance of B Johansen (Thorax 0 Bjortuft 1993;48:381-384) an Olympus paediatric fibreoptic broncho- J Boe scope (BF 3C10) with an outer diameter of Received 1O June 1992 3-9 mm. Returned to authors Few tests are available to measure the func- 24 August 1992 Revised version received tion of a single lung. Isotope scans provide STUDY DESIGN 15 October 1992 the fractional distribution of perfusion and Lung volumes Accepted 17 November 1992 ventilation to each lung and are used in the Static lung volumes were measured under 38232ohansen, Bjortuft, Boe BTPS conditions by the closed circuit helium saline was injected to inflate the balloon and dilution method with a Gould automated sys- the subjects were told to breathe quietly while tem 2400 (Sensormedics BV, Bilthoven, The being connected to the mouthpiece of the Netherlands). Inhalation of the gas mixture spirometer. At the end of a normal expiration started at the subjects' functional residual they were connected to a mixture containing Thorax: first published as 10.1136/thx.48.4.381 on 1 April 1993. Downloaded from capacity (FRC). The equilibrium criterion helium and continued tidal breathing until was set to 0 05%. Oxygen was delivered auto- the equilibrium criterion was reached. During matically. The vital capacity (VC) manoeu- equilibration, one or two slow VC manoeu- vres were performed near the end of vres were performed. The balloon was deflat- equilibration. From the FRC and VC record- ed immediately after each test. Usually four ings, values for total lung capacity (TLC) and unilateral and two bilateral measurements residual volume (RV) were derived. When were made in each subject: two with the bal- unilateral values for TLC, FRC, and RV loon inflated in the right lung, two when it from one lung were added to those of the was blocking the left lung, and two with the other, 85 ml was subtracted from the total to balloon deflated. The subjects had a repeat correct for the volume of the upper airway, bronchoscopy when the catheter was moved trachea, and mainstem bronchi that had been from one mainstem bronchus to the other. measured twice.5 Reference values for TLC When the balloon was in the short right were those of the European Community for mainstem bronchus its position was often Coal and Steel.4 checked between duplicate measurements. Insertion procedure Safety After premedication with atropine, diazepam During the insertion and measurement proce- and hydrocodone, the seated subjects inhaled dure the heart rate and oxygen saturation 5 ml of 2% nebulised oxybuprocaine via a were recorded continuously by a Minolta nasal mask. The nostrils and the posterior Pulsox-7 oxygen saturation monitor. wall of the pharynx were also sprayed with Whenever the balloon was inflated, one tech- lignocaine aerosol. The bronchoscope, coated nician held the syringe and was ready to with 2% lignocaine gel, was inserted into the deflate it within seconds if necessary. The left nostril and advanced until the glottis subjects were informed about possible became visible. The slightly bent catheter unpleasant feelings when the balloon was with its stylet inside was advanced blindly inflated and were told to tap their fingers if through the other nostril until its tip became they wanted it deflated during the test. visible. By twisting the proximal part of the catheter, sliding the stylet back and forth, and Randomisation and statistics changing the position of the subject's head, it The subjects were examined in the order they http://thorax.bmj.com/ was relatively easy to steer the catheter, fol- had been recruited. The order of measure- lowed by the bronchoscope, between the ment of the right, left, or both lungs was ran- vocal cords and into the trachea. The stylet domised for each subject according to a was then removed and the tip of the catheter complete block design. SPSS (Statistical placed in one mainstem bronchus. Extra topi- Package for the Social Sciences) was used for cal anaesthesia was usually needed, both in the data entry and analysis. Reproducibility the trachea and in the mainstem bronchi, to was expressed as the standard deviation of a avoid coughing. single determination (standard deviation of on September 30, 2021 by guest. Protected copyright. the difference between duplicates divided by Balloon position check the square root of two). Comparisons The subjects were asked to inhale as deeply between mean values for each variable from as possible and then to hold their breath. each lung and from both lungs were made by Under visual control the balloon was inflated the two tailed paired t test. rapidly with saline until it occluded the air- way completely. On the right side the balloon Ethical considerations was inflated at the level of the orifice to the Each subject was informed carefully about upper lobe, and on the left as far down the the purpose and content of the study, both mainstem bronchus as possible. The subjects verbally and in writing. All gave written then breathed normally for three or four informed consent to participate. The study breaths while the position of the balloon was was approved by the Regional Health Area checked before it was deflated. The inflation Ethical Committee. and deflation procedure was repeated several times to adjust the position of the balloon and the necessary volume of fluid. The catheter Results was then fixed to the nostril by tape and a PRACTICAL nose clip, the bronchoscope removed and the The bronchoscopic procedure, including subjects were placed in front of the spiro- positioning of the balloon, lasted 9-21 min- meter still seated. utes. The whole procedure, including neces- sary repeat bronchoscopies and the six Test procedure measurements lasted an average of 62 min- The subjects had been made familiar with the utes (range 51-74).