Chest physiotherapy in chronic obstructive pulmonary disease: Forced expiratory technique combined with either postural drainage or positive expiratory pressure breathing

Respiratory Medicine (1994) 88, 435440

Chest physiotherapy in chronic obstructive pulmonary disease: forced expiratory technique combined with either postural drainage or positive expiratory pressure breathing L. OLSI~NI*82 B. MIDGRENf, Y. H6RNBLAD~ AND P. WOLLMERw

Departments of *Physical Therapy, tLung Medicine and w Physiology, University of Lurid, Lund, and ~Department of Lung Medicine, Malta6, Sweden

The aim of this study was to measure the short-term effects on mucus clearance after forced expiratory technique (FET) combined with either postural drainage (PD) or positive expiratory pressure breathing (PEP) on two different days. We also wanted to assess the patient's preference to the two methods. We measured mucociliary clearance at rest and during physiotherapy in 14 patients with chronic obstructive pulmonary disease. The subjects inhaled an aerosol containing 99mTc-labelled albumin colloid. Five sets of scintigraphic images were obtained with 22-rain intervals. Lung retention of radioactivity was quantified using a gamma camera and the clearance of particles from the lungs calculated for each 22-min period. The first image was obtained directly after inhalation, the second after a period of 22 min rest, the third after physiotherapy and the fourth and fifth images after further periods of rest. Clearance from the whole lung and from central and peripheral regions were much greater after physiotherapy than at rest. Clearance during P D + F E T was significantly higher than during PEP+FET in the total lung field (P<0'05) and in the peripheral region (P<0'004). The patients found the two methods equally efficient but most of the patients preferred PEP as a treatment.

Introduction

Bronchial hypersecretion is an important feature of chronic obstructive pulmonary disease (COPD). Cough and mucociliary clearance are therefore important defence mechanisms. Patients with chronic bronchitis usually have impaired mucociliary clearance compared with normal subjects (1,2). Several techniques of chest physiotherapy have been tried in order to improve mucus clearance in patients with bronchial hypersecretion. Increasing emphasis is being placed on chest physiotherapy techniques suitable for self-administration and easily acceptable for the patient (3,4). A method used very frequently is postural drainage (PD) combined with forced expiratory technique WET) (3,5,6). During the last years positive expiratory pressure (PEP) breathing combined with FET has been introduced (7,8). P D + F E T and PEP+FET have been compared in patients with Received 21 September 1992 and acceptedin revisedform 7 June 1993. ~qTowhom correspondenceshould be addressedat: Departmentof Lung Medicine,Lasarettet,S-221 85 Lund, Sweden. 0954-6111/94/060435+06 $08.00/0

chronic bronchitis and with cystic fibrosis (9 11). The results have been conflicting concerning clearance of secretions from the airways. The immediate effect of the two treatments on mucus clearance in patients with chronic bronchitis has been compared in only one study of seven patients (9). P D + F E T improved mucus clearance whereas PEP+FET did not. The relative efficacy of PD and PEP as adjuncts to F E T is not clear from this study, since there were also other differences between the two regimens, e.g. duration of treatment. Hofmeyer and co-workers showed that P D + F E T produced more sputum than P E P + F E T in a study of 14 patients with cystic fibrosis (11). Mortensen and co-workers found in a study of ten patients with cystic fibrosis that both P E P + F E T and P D + F E T improved tracheobronchial clearance and did not find any significant difference between the two treatments (10). The aim of this study was to evaluate the shortterm effects of P D + F E T and PEP+FET on whole lung and on regional lung mucus clearance in patients with chronic bronchitis. We also wanted to assess the patient's attitude to the two methods. 9 1994W. B. SaundersCompany Ltd

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Aerosol inhalation l

22 min

I [ ?

Rest 1

22 min

I

22 min

Intervention

7

J

Rest 2

7

22 min

I

Rest 3

7

7

Fig. 1 Experimental protocol. Scintigraphic imaging is indicated by 7. A transmission scintigram was first obtained. The

subject then inhaled the radioactive aerosol and a set of images was obtained. Further scintigraphic images were obtained after periods of rest and physiotherapy. Materials and Methods PATIENTS

Fourteen patients (six females and eight males) with a history of chronic bronchitis (daily cough and expectoration for at least three consecutive months for the last 2 yr (12) took part in the study. They were recruited among the outpatients of the department of lung medicine and they had no other lung disease. Their mean age was 57 4- 12 (SD) years. Their sputum production by history was quite variable, ranging from 20 to 100 ml. There were six current smokers consuming 2 0 4 0 cigarettes d a y - 1 . None of the patients had previously been in contact with a physiotherapist. The treatments were performed in random order on separate days, usually with 2 days between the study days. Smoking was not allowed 1 h before the study and the patients were not allowed to inhale any bronchodilators 6 h before the study. The patients' attitude to the treatments was assessed on both study days. The patients were first asked how efficient they considered the treatment to be, i.e. how well sputum was cleared from the airways. The patients were then asked how strenuous they found each treatment with respect to breathing against a resistance, forced expirations and postural drainage. Answers were recorded on a scale from 0 to 3, 0 representing 'Not at all' and 3 'Very much'. On the last study day they were also asked which of the two regimens they preferred.

deep breathing and six forced expirations was repeated five times in each drainage position. PEP A N D FET

The PEP system consisted of a face mask and a one-way valve to which an expiratory resistance had been attached. The resistance was adjusted so that the patient was expiring against a pressure of 12-20 cmH20. One minute of PEP-breathing in the sitting posture was followed by forced expirations and a short period of relaxation and breathing control. The mask was used ten times during a session. The number of forced expirations was thus identical in the two regimens. L U N G F U N C T I O N MEASUREMENTS

Dynamic and static lung volumes were measured after physiotherapy on the first study day. We measured forced expiratory volume in one second (FEV1), vital capacity (VC), total lung capacity (TLC), residual volume (RV) and functional residual capacity (FRC). Static lung volumes were measured with the nitrogen washout technique. In addition to lung volumes we calculated lung clearance index (LCI=washout volume/FRC). Predicted values were obtained from Berglund et al. (13) and from Swanberg (14). We also wanted to measure static lung volumes with a PEP-valve connected, it was attempted in all patients and was Successful in eight. MEASUREMENTS OF M U C U S C L E A R A N C E

P D A N D FET

Two postural drainage positions were used for 10 min each: the right and left decubitus position. In each position deep breathing was performed for 1 min, followed by FET. F E T consisted of forced expirations ('huffs') from mid lung volume to low lung volume followed by a short period of relaxation and breathing control (6). Each period of F E T included six forced expirations with a short period of relaxation after three expirations. The sequence of

Mucus clearance was assessed with a technique based on measurements of the clearance of inhaled radiolabelled particles. The experimental protocol is outlined in Fig. 1. The subject was in a seated position in front of a gamma camera (Maxicamera 400T, General Electric Company, Milwaukee, WI, U.S.A.). A transmission scintigram of the chest was obtained using a flood source (Fig. 2). A flood source containing 57Co was placed over the anterior aspect of the chest and the ),-rays transmitted through the

Chest physiotherapy in chronic bronchitis

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Table 1 Lung function measurements (mean 4- 1 so) in % of predicted values n=14 VC FEV1 TLC RV FRC LCI

77 -4-13 59 + 15 94 4- 19 116 • 39 116 4- 36 200 4- 51

The number of spontaneous coughs was counted during each period of measurement. D A T A ANALYSIS

Fig. 2 Selectionof regions of interest. The regions were chosen in the transmission scintigram and subsequently projected onto the aerosol scintigrams. One region included the entire lung fields, one region the central parts and one region the peripheral parts of the lungs.

thorax detected with the 7-camera in the posterior view. This scintigram was used in the data analysis to delineate the lungs. The subject then inhaled a radiolabelled aerosol. An air jet nebulizer was used to nebulize a suspension of 99mTc-labelled albumin colloid (Microlite, Du Pont Scandinavia AB, Kista, Sweden). The particle size was 4.9 r mass median diameter with a geometric standard deviation of l'9/~m (measured with a light scattering technique). The subject was instructed to inhale the aerosol by somewhat forced deep inhalations. The inhalation was stopped when a count rate of 1500-2000 s 1 had been reached, corresponding to a delivered dose of approximately 20 MBq of 99mTC '

Five sets of scintigraphic images were obtained with exactly 22 min intervals. Each set of scintigrams consisted of images in the anterior and the posterior view, acquired for 2 min and stored in a 64 x 64 image matrix in a computer. A total of 150 000250 000 counts were accumulated over the lungs in each image. The first set of images was obtained immediately after the inhalation of the aerosol. The patient was allowed to rest in the sitting posture for 22 rain before the second set of images was obtained. Physiotherapy was then performed for 20 min and the third set of images was obtained after 22 min. A second and a third period of 22 min rest were followed by a fourth and a fifth set of images.

Regions of interest were delineated in the transmission scintigram and subsequently projected onto the aerosol scintigrams. Three regions of interest were selected for each lung; total lung, central part and peripheral part (Fig. 2). The central part was chosen as one fourth of the whole lung region of interest and the peripheral part was the difference between the other two regions. The clearance of inhaled particles was measured as the decrease in count rate between successive sets of scintigrams for each of the three regions. For each measurement, the mean value of the count rates in anterior and posterior views was used. A correction was made for the transport of particles from the peripheral to the central region when clearance from the central part of the lung was calculated. The results are presented as mean-4-one SD. The Friedman test and Wilcoxon signed-rank test were used for statistical analysis. The study was approved by the local research ethics committee and informed consent was obtained from each patient.

Results

Lung function measurements showed signs of airflow obstruction with reduced FEV 1 and increased RV (Table 1), none of the patients had a significant l~ronchodilator reversibility indicating asthma. No patient showed clinical signs of emphysema. Transfer factor was not measured systematically, and mild emphysema can therefore not be excluded. Eight patients could perform measurement of nitrogen washout during PEP. FRC increased during PEP in six patients, was unchanged in one and decreased in one. Mean values ( + 1 sD) with and without PEP were 121 + 26 and 107 + 49% of predicted,

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Table 2 Number of coughs during the study (mean value 4- 1 SD)

n= 14

PD+FET

Rest 1 Intervention Rest2 Rest 3

total lung field (P<0.05) and in the peripheral region (P<0"004). The patients in general found the two methods equally efficient, with a mean rating of 2 • 0-9. On average, the patients found P D + F E T to be somewhat more strenuous than PEP+FET, mean scores being 1.6 • 0"8 and 0"9 + 0'9, respectively. Nine patients, preferred PEP, one PD and four were indifferent.

PEP+FET

2 -4- 3

3• 4

13 -4-6 34-4 1•

13 • 6 2• 24-2

Discussion

respectively (NS). A reduction in LCI during PEP was observed in all patients but one (P<0'04), mean values with and without PEP being 163 4-43 and 196 + 51% of predicted, respectively. The scintigrams obtained immediately after the inhalation of aerosol showed prominent deposition of particles in the central airways. On average 52% 4- 10 and 52% 4- 11 of the aerosol was deposited in the central regions on both study days. There was no statistically significant intra-individual difference between the days. There was no statistically significant difference in the number of coughs between the study days (Table 2). Clearance from the whole lung and from central and peripheral regions were much greater during physiotherapy than at rest (Fig. 3). There was little difference in mucus clearance during the different periods of rest. Especially, there was no significant difference in clearance during the first period of rest on the two study days. A Friedman analysis showed a statistically significant difference between periods of measurements for the central and peripheral region during PEP (P<0'003), for the central and peripheral regions during PD and for the whole lung during PEP and PD (P<0.001). Clearance during P D + F E T was significantly higher than during PEP+FET in the

80

The aim of the study was to evaluate the shortterm effects of P D + F E T and PEP+FET on mucus clearance and also to assess the patient's attitude to the two methods. The study design allows each of the interventions to be compared to periods of rest before and after physiotherapy on the same study day. The two regimens are compared on different study days. The comparison of mucus clearance on different study days relies on reproducible deposition of the radioactive aerosol in the lungs. We found no difference in the initial distribution of radioactivity on the two study days. Furthermore, there was very little difference in clearance during the first period of rest on the two study days. The difference in clearance during the period of intervention can thus not be explained by a difference in aerosol deposition. FET and cough is considered important in order to improve mucus mobilization in patients with hypersecretion (4-11). In this study we standardized the number of FET in the two regions and the number of spontaneous coughs were noted. Since there was no difference in the number of coughs during the two study days this cannot account for the observed difference in mucus clearance.

80, '(b)

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Fig. 3 Clearance of radioactive particles from the lung regions [(a) whole lung, (b) central, (c) peripheral] at rest and during

physiotherapy expressed as the amount cleared during each period of measurement relative to the initial activity at the beginning of each period. ([:]) PD+FET, (N) PEP+FET. tSignificant difference PD+FET compared to PEP+FET (P<0.05), 1"tSignificant difference PD+FET compared to PEP+FET (P<0.004).

Chest physiotherapy in chronic bronchitis

Each of the two regimens significantly increased mucus clearance compared with the three periods of rest. While it is generally accepted that P D + F E T improves clearance (15), studies of PEP+FET have shown conflicting results. We found mucus clearance to be higher during PD+FET compared with PEP+FET in the whole lung and the peripheral region. Van Hengstum and co-workers found that P D + F E T was better than PEP+FET and that PEP+FET was not significantly better than control. The duration of the two regimens were not equal (PEP+FET was 20 min and PD+FET was 30 min) and the number of patients were only seven. A suggested mechanism for increased mucus clearance during PEP breathing has been an increase in collateral ventilation and opening of airways that are obstructed during tidal volume breathing (16). We found a reduction in LCI and an increase in FRC which would be compatible with this theory. If this is the mechanism for an increased clearance, clearance might be expected to increase especially in the peripheral field. We found, however, PEP+FET to be inferior to P D + F E T especially in the peripheral field. An opening of peripheral airways was probably achieved also during PD+FET by the deep breathing exercises. The mechanical effects of increased lung breathing excursions could provide a milking action on goblet cells and lung parenchyma. This should result in mobilizing mucus out of the airways (17). Deep breathing excursions are perhaps more important than increased FRC for mucus clearance. In order to avoid exacerbations of the chronic bronchitis it might be useful to clear the airways daily from secretions. Frischknecht and co-workers (4) recently found that PEP as a home treatment led to fewer symptoms and less exacerbations compared with diaphragmatic breathing exercises. In this study, we had the impression that tidal volume tended to decrease with time during PD unless the patient was repeatedly instructed to take deep breaths. It was, on the other hand, quite easy to instruct the patients to use the PEP-mask. On average, the patients found both treatments to be equally effective. The difference in efficiency found in objective measurements was thus not perceived by the patients. Most patients preferred PEP+FET. Major complaints during P D + F E T were aching shoulders and hips. This is in agreement with a recent study where Currie and co-workers (18) found poor compliance for PD, many of them complaining of discomfort and pain. Patient acceptance thus seems to be better for PEP than for PD. In the long term, this may lead to a better patient compliance.

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In conclusion, we found both P D + F E T and PEP+FET to increase mucus clearance. Clearance during PD+FET was significantly higher than during PEP+FET. The difference in efficacy of the treatments must be considered in relation to patient preference.

Acknowledgements This study was supported by grants from the Swedish National Association Against Chest and Heart Diseases.

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