Breathing comfort associated with different modes of ventilation: a comparative study in non-intubated healthy...

To compare subjective experience of comfort associated with various commonly used supportive modes of mechanical ventilation for weaning in the intensive care unit (ICU).

The study was carried out in general ICU of a community-based teaching hospital in 30 healthy adult Nepalese volunteers of either sex and 19-37 years of age. The subjects were randomly made to experience breathing via anatomical facemask through ventilator circuit with synchronized intermittent mandatory ventilation (SIMV), assisted spontaneous breathing (ASB), biphasic positive airway pressure (BiPAP), and continuous positive airway pressure (CPAP) modes of ventilation with parameters set at intermediate level of respiratory support. Subjective comfort of breathing was noted using a 10 cm visual analogue scale (VAS) with no discomfort at one end and maximum imaginable discomfort at the other. Inspiratory and expiratory experience of discomfort was also noted using a four point ranking scale (0-no discomfort, 1-mild discomfort, 2-moderate discomfort and 3-severe discomfort). In addition, presence or absence of feeling of breathlessness and inflation was also noted.

BiPAP was the most comfortable mode of ventilation (p<0.01) on visual analogue scale. SIMV and CPAP modes were associated with higher discomfort than other modes during inspiratory and expiratory phases respectively. Breathlessness and inflation were least felt in BiPAP and SIMV modes respectively.

Perception of breathing comfort can vary widely with various supportive modes of ventilation in the ICU. Hence, no single supportive mode should be used in all patients during weaning from mechanical ventilation. Key words: assisted spontaneous breathing; biphasic positive airway pressure; breathing comfort; continuous positive airway pressure; mechanical ventilation; supportive modes synchronized intermittent mandatory ventilation; weaning.