The present study investigated the influence of respiratory affections on the heart rate variability (HRV) of paediatric patients. We have hypothesised that respiratory physiotherapy would promote a beneficial effect on the cardiac autonomic modulation. Twenty-four children, who were divided into respiratory disease group (RG) and control (CG) groups, were studied. Analysis of HRV was performed with the RG in the dorsal decubitus position during four different moments: basal record (30 minutes); 5 minutes after respiratory physiotherapy by means of airway clearance techniques (10-minute record); 5 minutes after nasotracheal suction (10-minute record); and 40 minutes after nasotracheal suction (30-minute record). CG group was submitted to the same protocol, except nasotracheal suction, which was not performed due to ethical reasons.

The study of heart rate variability (HRV) is a method allowing non-invasive and selective evaluation of the changes in cardiac autonomic modulation. Its use in several clinical situations has provided important information, serving as an evaluation instrument for a better understanding of the involvement of the autonomic nervous system in various physiopathological situations.

With regard to the applicability of HRV analysis in paediatric populations, it is known that the maturity progression of sympathetic and vagal divisions is accompanied by a growing increase in autonomic modulation over the pre- and post-natal periods. In turn, a few studies have addressed the association between pathological paediatric conditions and changes in the cardiac autonomic modulation, consequently, HRV.

Among these pathologies, the respiratory affections are the main factors of morbidity and mortality in children, since newborns have peculiar aspects involving the respiratory system that can easily lead to a lung failure. Within this context, one can note the importance of the respiratory physiotherapy as an intervention using specific procedures in each case in order to decrease the airway resistance and improve the ventilation/perfusion ratio, thus improving the respiratory function and minimising the clinical severity. Consequently, in patients suffering from obstructive pathologies or neuromuscular dysfunctions, which makes cough an inefficient mechanism, physiotherapy can help them to recover from their condition.

Therefore, the respiratory physiotherapy has influence on the several hospitalisation phases, contributing to make the hospital stays shorter and less difficult to the paediatric inpatient and promoting a more humanised and more efficient environment based on the patient's needs. In this sense, it is possible that the paediatric inpatients present important alterations in their cardiovascular autonomic control, since constant oscillations in the cardiac and hemodynamic parameters are observed. However, studies correlating HRV with respiratory pathological conditions in paediatric inpatients are rare, either before or after the respiratory physiotherapy procedures, such as application of airway clearance techniques.

Inclusion Criteria:

• hospitalized children

Exclusion Criteria:

• age above 12 months;
• presence of cardiovascular disease or chronic respiratory disease;
• prescription of vasoactive drugs or sedatives;
• invasive mechanical ventilation;
• children on contact or respiratory isolation.