Physiological effects of vibration in people with cystic fibrosis; implications for COVID-19 rehabilitation.

Vibrotherapy has been used in patients with cystic fibrosis (CF) in order to facilitate the removal of the respiratory tract secretions. There are known manual techniques such as vibrations or tapping but also automated techniques with the use of oral devices, e.g. Flutter®, Acapella® or the positive expiratory pressure (PEP) device {Morrison and Milroy [2017] have reviewed the oscillating devices widely used in the CF clinic, also describing the vibrating vests; editorial note}.

In the presented article, special attention was paid to hand-delivered (manual) vibrations. Vibrations during manual massage rely on performing oscillating movements combined with pressure on the patient’s chest wall. The goal of Australian scientists from the University of Sydney was to compare the physiological effects of manual vibrations to other physiotherapeutic interventions used in clearing the airways of CF patients and to relate them to appropriate physiological mechanisms.

• No adverse effects were reported during the intervention.
• The mean peak expiratory flow rate (PEFR) during manual vibrations was:
  1.4 times greater than the Flutter® intervention;
  1.9 times higher than for tapping;
  2.7 times higher than for the intervention with Acapella®;
  3.6 times higher than for the PEP intervention.
• No significant effect of disease severity on PEFR was found when using manual vibrations.

Prepared on the basis of:

Physiological effects of vibration in subjects with cystic fibrosis. McCarren B, Alison JA. Eur Respir J. 2006 Jun;27(6):1204-9.

Study population

A total of 18 people (seven women) diagnosed with CF volunteered for the study. Mean age: 28.5 ± 6.2 years; mean body mass index: 20.8 ± 2.8 kg m-2. The mean forced expiratory volume in 1 second was 55% of the expected. Six patients had severe lung disease, eight had moderate lung disease, one had mild lung disease, and three patients had normal lung function.

Test procedure

All interventions were performed in one session. These included: manual vibrations, tapping, PEP, Flutter® and Acapella®.

Each type of intervention was repeated so that each patient performed the given intervention three times. The order of all interventions was random.

Use of vibration in the study

Manual vibrations administered by physiotherapists consisted of performing oscillatory movements combined with pressure on the patient’s chest wall. They were applied to the chest wall while exhaling following a slow maximal inhalation. The subjects were asked not to put any effort into the exhalation. The tapping was applied manually while breathing calmly. During both vibration and percussion the subject was laying on the side of the body that was less affected by airway secretions, exposing the more productive side to manual vibrotherapy. If there was no difference in sputum production between the left and right lungs the exposed side of the body was randomized. Patients were sitting upright while testing PEP, Flutter®, and Acapella®.

When using the Flutter®, the device was almost horizontal to maximize the oscillation amplitude aiming to achieve an oscillation frequency in the range of 10-15 Hz. According to previous studies, this frequency range has the greatest effect on mucus mobilization. Acapella® has been used according to the manufacturer’s (DHD Healthcare) recommendations with resistance set to the minimum level; each patient could feel the vibration for 3-4 seconds while exhaling.

The vibration frequency of the physiotherapeutic interventions used was determined by analyzing the frequency spectra:

• Manual vibration – 8.4 ± 0.4 (7.3-10.0)
• Percussion – 7.3 ± 0.3 (6.5-8.0)
• Flutter® – 11.3 ± 1.5 (7.5-13.7)
• Acapella® – 13.5 ± 1.7 (10.0-18.3)

Results

No adverse effects were reported during the intervention. No significant difference was seen in the perceived effort involved in any intervention. There was no significant effect of the order of intervention on the perceived effort.

The influence of physiotherapeutic interventions on the flow rate and tidal volume

The mean PEFR during manual vibration was 1.4 times greater than for the Flutter® intervention (p = 0.002), 1.9 times greater than for the tapping (p <0.001), 2.7 times greater than for the intervention with Acapella® (p <0.001) and 3.6 times higher than for the PEP intervention (p <0.001). There was no significant effect of disease severity on PEFR when using manual vibrations (p = 0.17).

There was no significant difference in inhaled volumes between the vibration treatments and the use of PEP, Flutter® or Acapella®. On the other hand, the inhaled air volume during vibrations was greater than during tapping (p <0.001).

There was no difference in the number of coughs between the interventions (p = 0.7).

Forced expiratory strategies

The mean PEFR of cough and huffHIGH were 2.9- (p <0.001) or 3.2-fold (p <0.001) higher than during the vibration, respectively.

Comment

The study compares the effects of various types of vibration physiotherapy – vibrotherapy: manual vibrations, tapping, variable bronchial pressure techniques using Acapella® or Flutter®, or the PEP technique of increased bronchial pressure. As shown in previous publications, all these physiotherapeutic interventions help move pulmonary mucus to the central airways from where it can be expectorated. This form of physiotherapy has also been shown to be more effective at clearing mucus than no intervention, but the exact mechanisms responsible for mucus removal in patients with CF are unknown. Understanding them can help in choosing the right treatment for symptom severity. Among the considered mechanisms, the following are proposed:

• increasing PEFR to move mucus to the oropharynx;
• improving the expiratory air flow to increase the annular flow of mucus towards the mouth and pharynx, which occurs when PEFR is 10% greater than the peak inspiratory flow rate (PIFR), i.e. PEFR/PIFR ratio> 1.1;
• increasing the transport of mucus by reducing the viscosity of the mucus and improving the expiratory flow due to the effects of air flow oscillations in the frequency range 3-17 Hz;
• induction of spontaneous cough by mechanical stimulation of the airways.

The results of the study show that manual vibrations resulted in higher expiratory flow dynamics and provided a higher PEFR/PIFR ratio than other physiotherapeutic interventions analyzed, with Flutter® and Acapella® having higher oscillation frequencies than manual vibrations.

The PEFR of manual vibration was greater than that of all other physiotherapy interventions. Manual vibration applied to the chest wall may increase the pressure within the pleura and therefore may increase the expiratory flow rate. In addition, during vibration we do not have to deal with additional resistance in the mouth, as in the case of using PEP, Acapella® or Flutter®, which would hinder the expiratory flow. So, external forces applied to the chest wall in the form of vibrations can more effectively increase the peak expiratory flow rate and, if the increase in expiratory flow contributes to the mucus removal mechanisms, the vibration may be a beneficial intervention in mucus removal – more effective than the other interventions analyzed.

The mean number of spontaneous coughs during the manual vibration sessions was less than 1 and did not differ significantly from other interventions. Perhaps, therefore, it is not the stimulation to cough that is responsible for the mechanism used by the analyzed interventions to remove pulmonary secretions.

The removal of secretions may be assisted by oscillations (vibrations) in the air flow. All analyzed physiotherapeutic interventions, with the exception of PEP, generated oscillations in the 3-17 Hz range which should, as shown earlier, facilitate mucociliary clearance. These oscillation frequencies can aid in the clearance of secretions by altering the rheology of the mucus and accelerating the rate of ciliary movement of stimulated ciliated epithelial cells. The oscillation frequencies of Flutter® (11.3 Hz) and Acapella® (13.5 Hz) were close to the optimal frequency for secretion removal (13 Hz – as shown in previous publications). The natural frequency of ciliary beats is 11-15 Hz, so delivering an oscillation of a similar frequency can cause the flowing air to resonate, increasing the amplitude of the cilia of the respiratory epithelium, which can directly increase mucus transport.

{The editors would like to correlate the presented research on CF with the suggestion of postcovid rehabilitation. In the era of COVID-19 pandemic, rehabilitation of pulmonary complications seems to be particularly important. Many years of clinical practice in using vibrotherapy to facilitate pulmonary secretions clearance in CF allows the hypothesis that vibrotherapy may also be effective in postcovid rehabilitation. It is especially noteworthy as the exposure of hospital staff to possible contact with the virus causing COVID-19 must be minimized so as not to block health care workers in quarantines. And current techniques of vibrotherapy make it possible to replace manual vibrations with automated systems that do not require the constant presence of a physiotherapist next to the patient. Vibrating vests generating high-frequency chest vibrations (The Vest®, VibraVest®, SmartVest®) used for years in cystic fibrosis physiotherapy should be tested first [Hill et al., 2018; Seitz et al. 2010], as well as vibrating belts that have already been tested in the clinical study of mechanically ventilated covid patients [Sancho et al., 2020]. In this context, it seems that the potential of other devices generating vibrations available on the market, already used in physiotherapy practice, should also be tested. In addition, COVID-19 symptoms often persist for weeks and months after discharge from hospital. Therefore, postcovid rehabilitation may be a long-term therapy, and so should be properly directed. The key is to test various forms of physiotherapy, already acting in other diseases, on symptoms similar to those observed in COVID-19. Therefore, it is worth looking at vibrotherapy that improves the quality of life even in chronic obstructive pulmonary disease [Gloeckl et al., 2012] or fibromyalgia [Collado-Mateo et al., 2015]. Editorial note.}

More in:

Więcej w: