Respiratory Medicine (1992) 86, 109-114

Humidification as an adjunct to chest physiotherapy in aiding tracheo-bronchial clearance in patients with bronchiectasis J. H. CONWAY*, J. S. FLEMING, S. PERRING AND S. T. HOLGATE

Medicine 1, Level D, Centre Block, Southampton General Hospital, Southampton S09 4XY, U.K.

Humidification of inspired air or oxygen is frequently utilized by respiratory physiotherapists to relieve sputum retention. Cold water, jet nebulizing humidifiers are in widespread use but there has been no previous attempt to investigate the efficacy of this treatment. We have performed a single-blind, cross-over study to quantify the effect of humidification as an adjunct to chest physiotherapy. Seven patients with bronchiectasis completed the trial, with a mean (range) age of 51 years (41-64 years) and mean (range) percent of predicted FEV~ of 46% (29-76%). On 2 days, separated by 1 week, subjects were randomly allocated to humidification or no humidification as a precursor to an optimal chest physiotherapy regimen. A radio-aerosol of human serum albumin millimicrospheres labelled with 99mTechnetium was used to measure sputum clearance by serial gamma camera images. Serial measurements of sputum weight and FEVj were also recorded. Humidification (30 min) was followed by postural drainage (20 min) with the subject using the forced expiration technique to assist clearance. When humidification was combined with physiotherapy there was a significant increase in total wet weight of sputum (P < 0"05) with a median (range) increase of 6 g ( - 9 - 1 5 ' 5 g); and a significant increase in total radiolabel clearance (P < 0-05) with a median (range) increase of 8.7% (1-13%), compared to physiotherapy alone. This study demonstrates that the use of cold water,jet nebulizing humidifiers significantly increases tracheo-bronchial clearance above that of an optimal physiotherapy regimen alone in bronchiectasis. We would suggest that this has important clinicial implications in the management of sputum retention in patients with hypersecretory lung disease.

Introduction

Gamma camera imaging of the thorax after inhalation of radiolabelled particles has provided a non-invasive technique to evaluate the dynamics of muco-ciliary clearance (1,2). By using this technique, an 'optimal" chest physiotherapy regimen of postural drainage and the forced expiration technique (FET) has been developed for treating patients with chronic, hypersecretory lung disease such as bronchiectasis (3). Cold water, jet nebulizing humidifiers have been in widespread use as an adjunct to chest physiotherapy; however, the efficacy of this treatment has not previously been evaluated. Indeed, substantial lack of information concerning any potential benefit of humidification systems has led to their withdrawal from some medical wards on both clinical and financial grounds. This study was designed to quantify the effect of cold water, jet nebulizing humidification on tracheobronchial clearance of sputum in patients with bronchiectasis when used as an adjunct to the present Received22 February !991 and acceptedin revisedform7 July 1991. *To whomcorrespondenceshould be addressed. 0954-6111/92/020109+ 06 $03.00/0

known optimal physiotherapy regimen, i.e. postural drainage and FET.

Methods

SUBIECTSELECTION Nine subjects (five male) with a clinical diagnosis of bronchiectasis (4) and chronic sputum production participated in the study. All were selected via respiratory outpatient lists. The mean (range) age was 49 years (41-64 years), and the mean FEV~ expressed as a percent of predicted was 41% (29-76%). All subjects had been suffering from bronchiectasis for greater than 10 years. No subject demonstrated a significant increase in pulmonary function indices following inhalation of salbutamol [defined as > 15% increase of actual values (5)]. Domiciliary physiotherapy and any prescribed bronchodilators were withheld on the morning of the trial. The study was approved by the Southampton University and Hospitals Ethical Committee and the Administration of Radioactive Substances Committee of the DHSS. © 1992Bailli6reTindall

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J. H. Conway et al.

HUMIDIFICATION A System 22 Misty Ox Nebulizing Humidifier was used during the study (Medic-Aid Ltd, Pagham, West Sussex, U.K.). This humidifier uses sterile water and operates as a large, single feed nebulizer. Compressed air was used to drive the humidifier with aerosol being delivered to the patient via 80 cm of hose to a face mask (Medic-Aid Ltd). A nose clip was used to ensure mouth breathing. Inhalation therapy was administered for a continuous period of 30min with the patient seated. The humidifier had previously been evaluated for particle size distribution using a Malvern Instruments HLS 2600c particle sizer (Malvern Instruments Ltd, Malvern, U.K.). The most appropriate flow rate for the three randomly picked humidifiers, when sampled on six occasions was 151 min -~. At this flow rate, the mean median diameter (MMD) was 4-9 #m, the geometric standard deviation (GSD) 1-8, and the mean output of the humidifier 0-5 ml min- t. CHEST PHYSIOTHERAPY The physiotherapy regimen adopted was postural drainage combined with FET. All subjects had diffuse lung disease with greater lower lobe involvement than upper. Postural drainage positions chosen were for the left and right basal segments of the lungs, with l0 min being spent in each position. The positions for drainage of these areas are the right and left lateral positions tilted head down 20 ° (6). Subjects were encouraged to expectorate throughout. The FET consisted of one or two forced expirations from mid lung volume followed by a voluntary cough (6). After being taught FET and having the procedure checked, subjects were asked to perform the manoeuvre every 2 min, or 2 min after spontaneous productive coughing. ASSESSMENTOF TRACHEO-BRONCHIALCLEARANCE Tracheo-bronchial clearance was quantified using a radio-aerosol of human serum albumin millimicrospheres (HSA) (CIS International, High Wycombe, U.K.) labelled with 99mTechnetium (99mTc). A closed nebulizer circuit using an Acorn jet nebulizer (MedicAid Ltd) driven by compressed air was used to deliver the radio-aerosol, the circuit being shielded by a lead surround. The subject inhaled the radio-aerosol via a mouth piece, while seated upright and breathing at tidal volume. After inhalation, a glass of water was swallowed to clear radiolabel from the oropharynx and oesophagus. The radio-aerosol circuit was previously evaluated for particle size distribution. The most appropriate flow rate for three randomly picked circuits, when sampled on six occasions, was 8 1min- ~.

At this flow rate the mean M M D was 4.3/tm, the GSD 1'9 and the mean output 0.2 ml min- ~. The radiolabel used to assess tracheo-bronchial clearance was generated from 4ml of 99mTc HSA (100 mBq ml -I) nebulized to 'dryness' over 13 min. The inhaled radioactivity did not exceed 30 mBq per study. QUANTIFICATIONOF RADIO-AEROSOL Serial posterior images in sitting were acquired during the day using a Siemens large-field-of-view gamma-camera and a parallel, high resolution, low energy collimator suitable for use with 99"Tc (International Electric Company, New York, U.S.A.). The acquisition time for each image was 60 s. Images were processed on a DEC VAX I 1-730 computer with Sigmex A7000 display processor and the images quantified by using PICS Image Processing software. Cobalt markers were used to provide positional information, Zones were created within a simple five by eight matrix to define central and peripheral deposition. The matrices were superimposed on the corresponding 99mTcimage once alignment had been verified. The initial deposition was assessed as the ratio of gamma-emission measured within the peripheral to the central zones and referred to as the penetration index. All counts were corrected for background and radioactive decay. The gamma-emission from the whole lung zone was used to estimate tracheobronchial clearance during each study day and expressed as a percentage of radioactivity cleared from the baseline. Each gamma camera image was analysed three times and a mean value taken. STUDY PROTOCOL A single-blind, cross-over design was used. On 2 days, separated by l week, subjects were randomly allocated to humidification or no humidification as an adjunct to postural drainage and FET. The randomization and inhalation therapy were blind to the person measuring outcome. All spirometry was measured, whilst standing, with a Vitalograph Compact Spirometer (Vitalograph Ltd, Buckingham, U.K.). All subjects attended the nuclear medicine department at 0900h, to minimize diurnal variation in sputum production. After 15 min rest a baseline FEV) was recorded. The subject then inhaled the radioaerosol and following l0 min rest, to allow for any free radiolabel to be dispersed, a gamma-emission image was recorded. Humidification was then administered for 30 min in a separate room, or, on the control day, the patient sat quietly for 30 min without any humidification. This was defined as the 'humidification' phase and any

Humidification and chest physiotherapy in bronchiectasis

111

Table 1 Subject characteristics

Sex

Height (cm)

Predicted FEV~ (I)

FEV, pre-salbutamol (% predicted)

41

M

178

3.97

57

M

186

3.85

64

F

162

2.09

53

M

173

3.41

46

F

152

2-25

45

M

173

3.46

52

F

163

2.54

1-52 (38) 1.44 (37) 1.30 (62) 1.00 (29) 0.73 (32) 1.57 (45) 1-93 (76)

Age (years)

FEV~ post-salbutamol

Predicted FVC (1)

FVC pre-salbutamol

FVC post-salbutamol

1.44

4-84

3-70

3-61

1-57

4-88

4-46

4.69

1.32

2.86

2-06

2-22

1.02

4.24

1-98

2.16

0.81

2.64

1.78

2.13

1.64

4.41

2-18

2.31

1.93

2.98

2.94

2.92

sputum expectorated during this phase was collected (pot I). Immediately following the humidification phase, FEV~ and a gamma-emission image were repeated. The subject then underwent 20 min of postural drainage and FET, defined as the 'physiotherapy' phase, and further sputum collected (pot 2). FEV t was measured and a gamma-emission image obtained. Finally, after a 30 min rest, seated in a chair, the 'rest' phase, a third collection sputum was made (pot 3) with FEV~ and gamma-emission imaging assessed for a fourth time. The total wet weight of sputum expectorated over one study day was defined as the sum of the wet weights of all three collections (pots 1-3); and the total amount of radio-aerosol clearance was defined as that measured at the end of the 'rest' phase i.e. the end of each study day. ANALYSES All results were analysed using the Wilcoxon signed rank test or the Spearman rank correlation coefficient. Median values with minimum to maximum ranges are used to illustrate spread of data

Results

Two subjects were withdrawn from the trial before completion, one with an intercurrent chest infection and one following the use of antibiotics for a urinary tract infection. Of seven subjects who completed four were male with a mean (range) age of 51 years (41-64 years) and a mean (range) percent predicted FEV~ o f 46% (29-76%). Table 1 describes the morphometric

and pulmonary function characteristics of these seven subjects. There was no significant difference between the two study days for baseline FEV~ or for the initial pattern of radio-aerosol deposition, as assessed by the penetration index. It should be noticed with interest that there was a significant correlation between the baseline FEV~ and the penetration index (P