Thorax 1990;45:623-627 623 Effect of forced expirations on mucus clearance in patients with chronic airflow obstruction: effect of lung recoil pressure Thorax: first published as 10.1136/thx.45.8.623 on 1 August 1990. Downloaded from C P van der Schans, D A Piers, H Beekhuis, G H Koeter, Th W van der Mark, D S Postma Abstract spontaneous mucus clearance, the effect of Spontaneous mucus clearance and the forced expirations with an open glottis at effect of forced expirations and coughing different lung volumes, and the effect of on mucus clearance were investigated in coughing in patients with sputum production. eight patients with chronic airflow ob- We studied two groups of patients with struction and low elastic recoil pressure similar degrees of airways obstruction, one (emphysema group: mean FEVy 45% with normal elastic recoil pressure and the predicted) and in seven patients with other with decreased elastic recoil pressure. chronic airflow obstruction and normal For convenience we have labelled the two elastic recoil pressure (chronic bron- groups "chronic bronchitis" and chitis group: mean FEVy 57% predicted). "emphysema." Mucus clearance was measured in a cen- tral and a peripheral lung region by a radioactive aerosol tracer technique. Methods Spontaneous mucus clearance from the MUCUS CLEARANCE MEASUREMENTS peripheral lung region was higher in the Mucus transport in the lungs was measured as patients with emphysema than in those described elsewhere.9 In summary, a radio- with chronic bronchitis. There was no active aerosol was generated by means of an difference in central mucus clearance intermittent positive pressure respirator between the two groups. Mucus clear- (Bennet AP-5); the nebuliser was filled with ance from the peripheral lung region 35-50 MBq (1-15 mCi) technetium-99m increased significantly during forced labelled tin colloid (Amersham; 95% of the expirations and coughing in the patients particles 1-15 gum). In this way, a hetero- with chronic bronchitis but not in those disperse aerosol is produced and 10-15% of http://thorax.bmj.com/ with emphysema. It is concluded that in the tracer would be deposited in the airways patients with chronic airflow obstruction after 40 inhalations. After inhaling the aerosol and regular sputum production sponta- patients were asked to wash their mouth and neous peripheral mucus clearance is drink water to clear their throat and oeso- greater in those with decreased elastic phagus of radioactive tracer. The initial whole recoil pressure. Physiotherapy that in- lung deposition pattern was quantified by cludes forced expirations and coughing expressing the amount of radioactive tracer in can enhance mucus clearance in such the central and peripheral regions as percent- on September 24, 2021 by guest. Protected copyright. patients when elastic recoil pressure is ages of whole lung deposition. In each of the normal but is unlikely to be effective four studies the radiation dose to the lungs when elastic recoil pressure is decreased. with this method is 0-6 mGy (60 mrad) and the effective total body radiation dose 0.1 mGy (10 mrad).'° Division of Physiotherapy, Clearance measurements were made with Department of Physiotherapy is commonly used to treat the patient lying supine. A gamma camera was Rehabilitation mucus retention in patients with chronic air- positioned behind the thorax and linked to a C P van der Schans flow obstruction. These patients often have computer for continuous acquisition of one Department of increased mucus production in addition. Al- minute frames for 35 minutes. For data Nuclear Medicine D A Piers though retention of mucus is a complex analysis an oval central region was determined H Beekhuis problem and due to many different factors visually on the monitor. The size of this Department of physiotherapy is usually given. The forced region was recorded on the basis of the length Pulmonary Diseases expiration technique,l" in which a forced of the x and y axes. The peripheral region was G H Koeter expiration with an open glottis is carried out defined as the total lung region minus the Th W van der Mark D S Postma at different lung volumes, is commonly used central region (fig 1). Thus the sizes of the University Hospital, in an attempt to mobilise mucus by providing central and peripheral regions were indivi- Groningen, The a high expiratory axial airflow velocity in the dually reproducible over the four days of Netherlands airways.' measurement. The total amount of radioactive Address for reprint requests: We wondered whether forced expirations tracer in both lung regions was printed out C P van der Schans, Academisch Ziekenhuis, were less useful in patients with mucus pro- after correction for physical decay. The secr. Fysiotherapie CMC I, duction who have decreased elastic recoil results were expressed as percentages of the Oostersingel 59, 9713 EZ Groningen, The pressure than in patients with mucus produc- starting value, defined as the amount of Netherlands. tion and normal elastic recoil pressure. The radioactive tracer measured in the period 0-1 Accepted 2 April 1990 aim of the present study was to evaluate minute. The decrease of radioactive tracer was 624 van der Schans, Piers, Beekhuis, Koeter, van der Mark, Postma Figure 1 Example ofa total lung region (a); the peripheral region (b) is found by subtracting the central region (c) from the total lung region. Thorax: first published as 10.1136/thx.45.8.623 on 1 August 1990. Downloaded from considered to reflect mucus transport in the Mucus clearance measurements were per- lungs. formed on each study day. The protocols were started after inhalation of the radiolabelled PATIENTS aerosol. After each protocol the patient was Eight patients were selected on the entry visit asked whether the treatment had been effec- on the basis of the following criteria and tive in clearing the lungs. None of the patients categorised as having emphysema: regular had used the forced expiration technique daily expectoration of mucus, airflow obstruc- previously. During each protocol the patients tion with an FEV, below 80% predicted and were required to lie supine for 35 minutes. values below predicted after bronchodilata- Protocols II, III, and IV were used in a tion, static pulmonary compliance above randomised order; protocol I was carried out 110% predicted, total lung capacity above on the first study day. The four protocols 110% predicted or FEV,/FIV, below 60%, were: and circumstantial evidence of emphysema on Protocol I This was used for control the chest radiograph according to the criteria measurements and for measuring spontaneous of Simon et al." Seven patients with chronic mucus clearance. No physiotherapy was per- bronchitis were also selected on an entry visit. formed. These patients had also regular daily expec- Protocol II The patients breathed undis- http://thorax.bmj.com/ toration of mucus, and an FEV1 below 80% turbed for the first 10 minutes. Forced expira- predicted that was not fully reversible. They tions with an open glottis were then perfor- had to have a static lung compliance med from total lung capacity (TLC) every 30 measurement below 90% predicted and had to seconds for a further 10 minutes. Patients show no clinical or radiological symptoms or then coughed as productively as possible signs suggesting emphysema. Spirometry was every 30 seconds for five minutes. The last 10 performed with a water sealed spirometer. minutes again consisted of undisturbed Static lung volumes were assessed with a breathing. on September 24, 2021 by guest. Protected copyright. helium dilution technique. Pulmonary com- Protocol III This was the same as II except pliance was measured as outlined by Cotes."2 that the forced expirations were now perfor- Each patient with emphysema was matched as med at functional residual capacity (FRC). closely as possible for FEVy and smoking Protocol IV This consisted of 10 minutes of habits with a patient with chronic bronchitis. undisturbed breathing followed by a period of On the days of measurement the patients used coughing every 30 seconds for 15 minutes. their regular medication-that is, inhalation The patient then breathed again undisturbed steroids, ipratropium bromide, theophylline, for 10 minutes. and beta agonists. Routine physiotherapy was The patient took a drink of water to clear not performed on the days of measurement. the oesophagus of radioactive tracer after the The study was approved by the medical ethics forced expiration periods and after the cough- committee of the university hospital. All ing period. patients gave written, informed consent. PHYSIOTHERAPY Physiotherapy was always given by the same STATISTICAL ANALYSIS physiotherapist (C P vd S). The patients Differences in radioactive tracer clearance at underwent three different physiotherapy 10, 20, 25, and 35 minutes after starting the protocols (II, III, IV) and one protocol with- clearance measurements were compared with- out treatment (I) on four different days, in the two groups by means of analysis of always between 13.00 and 15.00 hours within variance. Differences between the two groups nine days. Peak expiratory flow (PEF) was were compared by means of Student's un- determined before each mucus clearance paired t test. In both tests a significant dif- measurement. The highest value from three ference was defined as p < 0 05. All calcu- technically correct manoeuvres was taken for lations were performed by using the SPSS analysis. statistical package.'3 Effect offorced expirations on