THE EFFECT OF MECHANICAL VIBRATION ON THE GASEOUS EXCHANGE AND LUNG FUNCTIONS OF PATIENTS WITH ACUTE LUNG INJURY

The use of chest physiotherapy is a well-established primary and supplemen­ tal treatment of patients with a variety of respiratory diseases. The purpose of the intervention is improvement of mucocilliary clearing, increased sputum produc­ tion, bronchodilatation and improvement of gaseous exchange. Respiratory physiotherapy techniques may be divided into two categories. The first, "pulmonary physiotherapy", in­ cludes techniques designed to reduce air­ way resistance, to improve intrapulmonary gaseous exchange and to reduce com­ plications like atelectasis and pneumonia. This group consists of postural drainage, chest percussion, vibration and stimula­ tion of cough. The second category, "breathing exercises", includes techniques to relieve dyspnoea, to improve ventila­ tion effectiveness and to improve exercise capacity.


INTRODUCTION
The use of chest physiotherapy is a well-established primary and supplemen tal treatment of patients with a variety of respiratory diseases.The purpose of the intervention is improvement of mucocilliary clearing, increased sputum produc tion, bronchodilatation and improvement of gaseous exchange.
Respiratory physiotherapy techniques may be divided into two categories.The first, "pulm onary physiotherapy", in cludes techniques designed to reduce air way resistance, to improve intrapulmonary gaseous exchange and to reduce com plications like atelectasis and pneumonia.This group consists of postural drainage, chest percussion, vibration and stimula tion o f cough.The second category, "breathing exercises", includes techniques to relieve dyspnoea, to improve ventila tion effectiveness and to improve exercise capacity.

Mechanical and Manual Vibration
There is a tendency in the literature for authors not to differentiate between man ual and mechanical vibration and chest shaking.For this reason, some regard rib fractures (the pathology in this study) as a contra-indication for vibration (Mackenzie 1989).Manual vibration is a gentle tech nique with a high frequency and small amplitude whereas chest shaking is a more forceful technique with a lower frequency and greater amplitude.
True manual vibration is not as widely used in clinical practice as some people assume because of the fact that it is a diffi cult and tiresome technique.Mechanical vibration that also produces a high fre quency and small amplitude is an appro priate alternative and, therefore, it was ap plied in this research.
The main reason for the study was to determine the effect of one specific tech nique (mechanical vibration) on gaseous exchange and lung functions in patients with acute blunt chest trauma.

Lung Conditions
Chest physiotherapy for patients with chronic airway diseases has been studied with varying results1,2 '3,6,15'16'18.There is little published data concern ing the effectiveness of chest physio therapy in the treatment of patients with acute lung injury.Mackenzie et al (1979) investigated the effects of postural drain age, percussion/manual vibration and cough stimulation/suctioning on oxy genation and chest X-rays (CxR) in me chanically ventilated patients.Improve ment in chest X-rays and no change in PaC>2 was shown.Conners et al (1980) stud ied the immediate effect of postural drain age and percussion on oxygenation in pa tients with acute pulmonary disorders.The study demonstrated a significant de crease in the PaC>2 after treatment in the patients that produced very little sputum and no change in PaC>2 in the patients who produced moderate amounts of sputum.Marini et al (1979) studied the effect of breath in g exercises/ baggin g, coughing/suctioning, inhalation, percussion and postural drainage on spontaneous breathing/mechanically ventilated pa tients w ith consolidation/atelectasis. Holody and Goldberg (1980) studied the effect of mechanical vibration on arterial oxygenation in acutely ill mechanically ventilated patients with atelectasis or pneumonia.The results showed a signifi cant improvement in the PaC>2 and pH.

PATHOPHYSIOLOGICAL BACKGROUND
Most injuries of the chest cause damage to the underlying lung leading to both un derventilation and ventilation-perfusion disturbances in the lung.The reduction in alveolar ventilation is due to five factors: were taken within 12 hours before the first and within 24 hours after the second treatment.For the ventila tion studies, the total group was di vided randomly in two groups -in one, ventilation studies were car ried out before and after the first treatment and in the other, the studies were carried out before the first and after the second treat ment.
There was s significant deterioration in PaC>2 two hours after the second treatment, and in PaC>2 and SaC>2 when the values two hours after the second treatment were compared to the values before the first treat ment.The CxR of only two of the patients in the experimental group showed improvement and the oth ers showed either no change or de terioration.
The forced vital ca p a city (FVC) showed a significant improvement after the first treatment, but no change after the second treat ment.The same was seen in the ventilation studies.

V____________ ____________J
• diminution of the respiratory drive be cause of pain.Instability of the chest wall is due either to multiple rib fractures, or to fractures of the ribs and the sternum.Unstable sections of the chest wall move paradoxically dur ing spontaneous breathing and waste ven tilatory effort.Pneumothorax and haemot horax compress the lung and further de press ventilation.Contusion of the lung and atelectasis reduce lung compliance, the work of breathing in increased, oxygen consumption rises and ventilation is fur ther reduced17.

Treatment of patients with blunt chest trauma (BCT)
Non-invasive treatment of BCT Recovery of lung volumes (FRC) can be achieved with a con stant positive airway pressure mask (CPAPM).PEEP as high as 10cm H2O can easily be given with a CPAPM.The advantage is that the patient can still cough and can also be ambulated earlier so that complications such as thrombo-embolisms can be mini mised.A CPAPM can also be given intermittently.In conjunction with the CPAPM, effective pain relief must be given (van Eeden 1990).

Mechanical Ventilation
Indications for ventilation after moderate to severe BCT are:

Choice of Patients
Fifteen patients with unilateral rib fractures (an example of blunt chest trauma), who were admitted to the Respiratory Criti cal Care Unit and were treated with a CPAP mask, were studied.Patients excluded were those: • older than 60 years • with head injuries • who had already been hospitalised for more than 72 hours • who, for some or other reason, could not be turned on the non-fractures side Patients were randomly divided (using a computer generated pseudo-random number sequence) into experimental and control groups.

Techniques
In the experimental group, the following physiotherapy tech niques were applied: Mechanical vibration (with a Vibramat at a frequency of 25000 revolutions per minute) over the affected lung areas for 10 min utes with the patient in side lying on the non-fractured side, and 10 minutes with the patient in supine.
Coughing was encouraged.
The control group of patients were treated using the same method except that mechanical vibration was not applied.The experimental and control groups were treated twice with a 4 hour break in between treatment sessions.

Measurements
The following changes were noted serially in all subjects: 1. Chest X-rays within 12 hours before the first treatment and within 24 hours after the second treatment (AP exposures).2. Blood analysis was performed on all the patients five minutes before and 30, 60 and 120 minutes after the first treatment.Before and after the second treatment blood gases were taken at the same time intervals.The measurements were all done in supine with the bed flat and the patients were in that position for at least 15 minutes prior to data collecting.3. Spirometry (using the Mina to Autospiro) was done at the same time intervals as the blood gases.The total sample was divided randomly into two groups.
In one group (consisting of eight patients -four from the experimental group and four from the control group) ventilation studies were performed five minutes before the first treatment and 120 minutes after the first treatment.
In the other group (consisting of seven patients -four from the experimental group and three from the control group) the venti lation studies were performed 5 minutes before the first treatment and 120 minutes after the second treatment.For the ventilation studies Krypton and Xenon were used.

Age, Sex and Injuries
The experimental and control groups were comparable accord ing to the mean age (39 years in the experimental and 40.8 years in the control group) and sex (in the experimental group men exceeded the women by 6:2 and in the control group by 5:2).
The two groups were also comparable according to additional injuries Five of the eight patients in the experimental group and four of the seven patients in the control group had a lung infection.Two of the patients in the experimental group produced copious amounts of sputum, five produced moderate amounts of sputum and one had an unproductive cough.Two of the patients in the control group produced copious amounts of sputum, one pro duced a moderate amount of sputum and four produced little sputum.
In the experimental group four of the eight and in the control group two of the seven patients experienced considerable pain and pain relief (Temgesic) was administrated six-hourly by epidural catheter.In spite of the pain experienced by some, the cooperation of all the patients was very good.

Blood Gases
In neither the experimental nor the control group did the PaC>2, SaC>2 or PaCC>2 values change significantly at any time interval

Fisioterapie, Mei 1994 Deel 50 no 2
Reproduced by Sabinet Gateway under licence granted by the Publisher (dated 2013.) after the first treatment.After the second treatment, in the experi mental group there was no significant change in the PaC>2 values 30 and 60 minutes after treatment, but at 120 minutes, the Pa02 value deteriorated significantly (p = 0.0481) (Fig 1).The values of the SaC>2 and PaC02 did not change significantly at any time interval.When the changes over the two treatments in the experi mental group were calculated, a highly significant deterioration in the Pa02 (p= 0.0562) and Sa02 (p = 0.0323) values were found 120 minutes after the second treatment.Both the p-values were significant at the 1% level according to the exact Wilcoxon test.The PaCC>2 values did not change.In the control group, there was no significant change in any of the blood gases at any of the time intervals after the second treatment or when the changes over the two treatments were calculated.0. 12 [ ---------------------------------------------------

Time after treatment (minutes)
Exparlnianlal Group Cantral Croup

Lung Functions
In the experimental group, there was no significant change in the forced vital capacity (FVC) value 30 and 120 minutes after the first treatment, but at 60 minutes there was a highly significant improvement (p = 0.0092) (Fig 2).
There was no significant change in the forced expiratory vol ume in one second (FEV1) and peak expiratory flow rate (PEFR) values at any of the time intervals.After the second treatment, there was no change in the FVC, FEV1 and PEFR values at any time interval.There were no significant changes in the lung functions when the changes over the two treatments were calcu lated and compared.
Calculation of the Trapezoid rule showed a significant (p = 0.0323) improvement in the FVC value after the first treatment (according to the exact Wilcoxon test it is significant at the 5% level).In the control group, there was no significant change in any of the lung function values at any time interval after the first or second treatment.

Chest X-rays
In the experimental group two of the Chest X-rays (CxR) showed improvement (the patients produced copious amounts of sputum), one showed deterioration (the patient had an unproduc tive cough) and in five (these patients produced moderate amounts of sputum) no changes were detected.In the control group, the CxR of three patients (two produced copious amounts and one a moderate amount of sputum) showed improvement and four (who produced little sputum) showed no change.

Ventilation Studies
The ventilation studies which were done before and two hours after the first treatment showed the following results: In the studies of two of the four patients in the experimental group, there were marked improvements.Both these patients produced copi ous amounts of sputum.One of the studies showed moderate improvement and the patient produced a moderate amount of sputum.The other study showed no change and the patient produced little sputum.
In the control group, the study of one of the patients showed marked improvement and the patient had unproductive cough.One showed marked deterioration and this patient produced a copious amount of sputum.The studies of the other two patients showed no change.Both produced little sputum.
The ventilation studies which were done before the first treat ment and two hours after the second treatment showed the fol lowing results: In the studies of three of the four patients in the experimental group, there were no changes.The study of the fourth patient had an interesting feature.The patient had four rib fractures on the right side and the second ventilation study showed no change on the right, but a slight reduction in ventila tion on the left.All of these patients produced moderate amounts of sputum.In two of the studies of the control group no changes were shown.One of the patients produced a copious amount of sputum and the other one very little.

Blood Gases
Because of the pain experienced as a result of rib fractures, especially fractures of the 9th to 11th ribs, there is a diminished respiratory drive plus impaired ventilation.Progressive alveolar atelectasis follows and this results in a smaller gaseous ex change17.Lung contusion causes decreased regional alveolar ven tilation, because of the blood and fluid in the alveoli, and de creased perfusion to the area of contusion.The decreased perfu sion is less than the decreased ventilation due to the loss of the normal pulmonary vasoconstrictory response because of the in jury to the capillaries.This leads to V/Q mismatching.
The average number of rib fractures in the experimental group was seven and four of the eight patients had rib fractures below the 9th rib.Four of the eight patients also experienced a consider able amount of pain.The average number of rib fractures in the control group was six and none of the patients had rib fractures below the 9th rib.Only two of the seven patients experienced considerable pain.The results of pain are mentioned above and it is clear that the gaseous exchange was the V/Q mismatching that occurred because of the patients' shallow breathing patterns.
According to Mackenzie et al (1978), mechanical ventilation with PEEP plays an important role in the re-expansion of col lapsed alveoli, which will lead to improved gaseous exchange and Pa02.The reason for the improvement in Pa02 in Holody and Goldberg's study (1980) and no deterioration in Mackenzie et al study (1978) was probably the mechanical ventilation with PEEP that was used in both studies and not necessarily the mechanical vibration that was applied.Craven et al (1979) found in their study of right lower lobe contusion in 12 dogs that the contusion produced an average decrease of 20 mmHg in Pa02-According to Mackenzie et al (1989), lung contusion may im prove after chest physiotherapy.The removal of bloody secretions from the areas of normal lung around the contused area, into which bleeding has occurred, may improve the intrapulmonary shunt.If the lung is severely contused and lacerated as a result of the injury, no im provement may be seen and there can even be a deterioration in the patient's condition after chest physiotherapy.
The decrease in PaC>2 and SaC>2 was only significant two hours after the second treatment and although it was statistically significant, it was not clinical significant and none of the patients showed signs of distress.

Lung Functions
The significant improvement in FVC of the experimental group 60 minutes after the first treatment (Wilcoxon: p = 0.0092) and also after the first treatment as a whole (Trapezoid rule: p = 0.0323) may indicate a decrease in airway resistance.The im provement was the greatest in the two pa tients who produced copious amounts of sputum.
The forced expiration during the FVC manoeuvre causes higher than normal transpulmonary pressures so that bronchiolar collapse, obstructive lesions, and air trapping are all exaggerated.In this case it did not happen, probably because of the mobilisation and removal of central secretions as a result of the mechanical vibration and coughing.

Chest X-rays
Mackenzie et al (1978) found in their study an improvement in the CxR of 68% of the patients in the study group.Marini e t al (1979) studied the effect of deep breathing/bagging, coughing/suctioning, inhalation, and percussion and pos tural drainage for five minutes on patients with acute lobar atelectasis.
The CxR of the patients with central obstruction in the group that received chest physiotherapy demonstrated ap proximately 37% restoration of volume loss immediately after the first treatment.Twenty four hours later 80% of the de creased lung volume was regained.
The CxR of the patients with consolida tion/atelectasis demonstrated no signifi cant improvement.According to Marini et al (1979), respiratory physiotherapy is beneficial in the removal of central secre tions, but not in the removal of viscous secretions from the peripheral airways with proximal bronchial obstruction.
Mackenzie et al (1989) state that it is still uncertain w hich com ponent of chest p h y sio th e rap y -p o stu ra l d rain ag e, breathing exercises, percussion, vibration, coughing, or tracheal suctioning -is most effective in clearing secretions from the smaller airways.The exact reason(s) for the improvement in the CxR in the Mack enzie et al (1978) and Marini et a l (1979) studies cannot be determined as a number of treatment modalities were used.Kigin (1981) also reported that when postural drainage and vibration were performed during bronchoscopy, only the secretions in the larger airways became evident.
According to Mackenzie et al (1989), a combination of postural drainage and ma noeuvres such as mechanical ventilation with PEEP probably increases the likeli hood of re-expansion of non-dependent atelectasis because the uppermost hemithorax is preferentially ventilated.

Ventilation studies
George et al (1985) studied the changes in mucocilliary clearance during high fre quency oscillation at 10 Hz (8-12 Hz) in seven non-smokers by monitoring the clearance of inhaled radiolabelled aerosol from the lungs.At three to four and a half hours, the mucocilliary clearance with high frequency oscillation exceeded the control by 10%.The mean time taken to eliminate 90% of deposited radio-aerosol from the tracheobronchial tree fell from four hours and 50 minutes to three hours 52 minutes during the high frequency os cillation run.
Kingef al (1983) studied the clearance of mucus in the trachea of nine anaesthetised dogs during high frequency chest wall compressions (HFCWC).The enhance ment of clearance during the two minutes of HFCWC was most pronounced in the range of 11 to 15 Hz, reaching a peak value of 340% at 13 Hz.They discussed several possible mechanisms for this effect.Vibra tion might reduce the crosslinking that holds the mucus glycoproteins together and facilitate mucus clearance.This possi bility is suggested by the fact that the en hancement of clearance sharply peaks in the 11 to 15 Hz range.
Pavia et al (1976) studied the effect of mechanical vibration at 41 Hz on the clear ance of lung secretions in 10 patients with chronic bronchitis.The removal from the lung of radioactive particles was precisely monitored for five hours by external moni toring.No significant difference was found in the rate of clearance of secretions from the lung when vibration was com bined with postural drainage.
The results of the present study suggest that mechanical vibration at 42 Hz is effec tive in p atients who produced large amounts of sputum as there was marked improvement in ventilation after treat ment.In patients who produced small to moderate amounts of sputum, the treat ment was ineffective.
The frequencies of 10 and 13 Hz used by George et al (1985) and King et al (1983) seemed effective in clearing secretions from distal airways.However, the appara tus used was apparently designed and manufactured specifically for their re search.The results of these studies and the present study suggest that mechanical vi brators generating frequencies of 8-15 Hz should be made more accessible.
In the group where the ventilation stud ies were done before the first and two hours after the second treatment, the fail ure of the or.e patient, who produced a large amount of sputum, to show im provement can possibly be attributed to the time of the study.George et al (1985) recorded the best mucocilliary clearance at three to four and a half hours and this study was done six and a half hours after the first and two hours after the second treatment.

CONCLUSION
From this study, the following conclu sion can be drawn: Mechanical vibration at 42 Hz does not mobilise secretions in pe ripheral airways and therefore atelectasis and gaseous exchange do not improve and can even deteriorate.It appears, however, that central secretions are mobilised by mechanical vibration and the airflow in the larger airways therefore improves.

INTRODUCTION
Facilities available for specialised neu rological and orthopaedic rehabilitation, based on the principle of a multidiscipli nary approach, are very limited in South Africa.This type of specialised treatment has primarily been available at academic hospitals and those hospitals under the control of the mining industry.The re sources available in these sectors have been put under enormous strain, thus lim iting the quantity and quality of rehabili tation offered to the physically disabled.

Barney Hurwitz Medical Institute
In November 1991, the directors of a large group of hospitals agreed to convert an already existing hospital into a private rehabilitation institute that would cater for both in-and out-patients.A neurologist and therapists were involved in setting up the departments of physiotherapy, occu pational therapy, speech therapy and so cial work.Nursing staff were responsible for setting up the wards for in-patients.
In February 1992, the establishment w as o p en ed , a d m ittin g p o st-acu te neurologically impaired and poly-trauma p atients for in ten sive reh abilitation .Within six weeks it was recognised that the staff establishm ent needed to be ex panded.By the end of May 1992, allied medical staff complement consisted of 2.5 physiotherapists, one occupational thera pist, one social worker, 0.5 speech thera pist, under a rehabilitation coordinator.A clinical psychologist was available on re ferral.
On admission to the institute, patients were assessed by each speciality, after which the therapists would confer and contract with the patient/caregiver.This allowed the patient and therapist a specific time to reach predetermined goals, as well as preparing the home environment for discharge of the patient.
The patients day was structured so that he was involved in a full day therapy pro gramme with therapeutic activities being carried over in the ward.The programme also included a day or weekends at home prior to discharge from the ward whereaf ter outpatient therapy could continue.In addition full day, half day or sessional pro grammes were available to out-patients.
Liaison between disciplines included weekly ward meetings involving medical, nursing andallied medical staff as well as a vveekly outpatient meeting.

Problems Financial
Although the hospital charged medical aid tariffs, a significant number of patients' medical aids had reached the limit of bene fits while the patient was still in an acute care hospital.
Representative Association of Medical Schemes (RAMS) refused to pay for serv ices rendered by the therapists in the em ploy of the hospital.
Government gazetted codes as set out by RAMS for physiotherapy do not in clude a tariff for patients receiving ex tended periods of rehabilitation, or for as sistants carrying out supervised exercise programmes.

Staff
The hospital required specialists in fields of physiotherapy, occupational ther apy, speech therapy, social work and nurs ing.such specialists are scarce and re quired appropriate remuneration.
Legislation did not allow physiothera pists to be employed by any organisa tion/person other than the state, the mines of an independent physiotherapist.

Discussion
The establishment of a private rehabili tation institute in South Africa is an inno vative and exciting concept.However, our medical resources do not provide for the comprehensive treatment and reintegra tion of the neurologically impaired indi vidual into society.In many cases, by the time the patients were medically stable and ready for rehabilitation, they had reached the limit of their medical aid bene fits and thus could not afford further treat ment.This resulted in patients being dis charged before reaching their maximal functional potential.Going home still functionally dependent to a unprepared environment puts considerable emotional and fin a n cia l stra in on fam ily and caregivers.
Large institutions running on business principles cannot provide this type of serv ice without showing a profit.Specialised therapists providing a professional service need to be suitably remunerated.Thus a balance must be found between the needs of society and the financial practicalities of running a private rehabilitation institute.
The cost of setting up a rehabilitation centre is substantial.Therefore, the bene fits to the patient and community need to be critically appraised.Literature has indi cated that rehabilitation in diagnostic groups is of maximal benefit predomi nantly due to the uniform approach to management (Flicker, 1989).This team ap proach should engender high moral, amongst the members and initiate re search which acts as a catalyst to improve patient care and standards of treatment.
Literature indicates patients rehabili tated on stroke units/wards leave hospital sooner than those on general medical wards (Millikan, 1979).This implies that hospital costs per patient may be less on a stroke unit' (Stevens et al, 1984).Results indicate a higher proportion of patients discharged from stroke units were inde pendent compared with those from gen eral medical units (Garraway et al 1980).Garraway found the mean length of stay in the stroke unit was 55 days in compari son to 75 days in a general medical ward.However, at one year follow-up the stroke unit benefit was no longer evident.Ongo ing community follow-up is more likely to be utilised by those patients who received rehabilitation in a stroke unit (eg district nurses, physiotherapists and day centres) (Garraway et al 1981).
Studies comparing formalised neuro rehabilitation with non-formalised treat ment in functional and cognitive skills have been undertaken.Results show those patients who took part in the formalised programme gained a greater functional ca pacity with implications for return to work and decreased cost to, society (Mackay).There is now clear evidence as to the bene fit to patients and cost effectiveness of skilled and appropriately delivered neuro rehabilitation (Brooks, 1991).

Figure 1 .
Figure 1.Changes in P a 02 after second treatment