Neurally adjusted ventilatory assist and pressure support ventilation in small species and the impact of instrumental dead space.
BACKGROUND
Neurally adjusted ventilatory assist (NAVA) is a pneumatically-independent mode of mechanical ventilation controlled by diaphragm electrical activity (EAdi), and has not yet been implemented in very small species.


OBJECTIVE
The aims of the study were to evaluate the feasibility of applying NAVA in very small species and to compare this to pressure support ventilation (PSV) in terms of ventilatory efficiency and breathing pattern, and evaluate the impact of instrumental dead space on breathing pattern during both modes.


METHODS
Nine healthy rats (mean weight 385 +/- 4 g) were studied while breathing on PSV or NAVA, at baseline or with added dead space.


RESULTS
A clear difference in breathing pattern between NAVA and PSV was observed during both baseline and dead space, where PSV - despite similar EAdi and tidal volume as during NAVA - caused shortened inspiratory time (p < 0.05) and increased the respiratory rate (p < 0.05). A higher minute ventilation (p < 0.05) in order to reach the same arterial CO(2) was observed. Ineffective inspiratory efforts occurred only during PSV and decreased with the dead space.


CONCLUSIONS
This study demonstrates, in a small group of animals, that NAVA can deliver assist in very small species with a higher efficiency than PSV in terms of eliminating CO(2) for a given minute ventilation.
Campoccia Jalde
Francesca
F
Department of Anaesthesiology and Intensive Care, Karolinska Hospital and Institute, Stockholm, Sweden.
Almadhoob
Abdul Raoof
AR
Beck
Jennifer
J
Slutsky
Arthur S
AS
Dunn
Michael S
MS
Sinderby
Christer
C
D000399:Air Pressure; D000818:Animals; D001921:Brain / Q000502:physiology*; D019544:Equipment Failure Analysis; D005240:Feasibility Studies; D008297:Male; D009424:Nervous System Physiological Phenomena; D051381:Rats; D017207:Rats, Sprague-Dawley; D012119:Respiration; D012121:Respiration, Artificial / Q000295:instrumentation* / Q000379:methods* / Q000592:standards / Q000662:veterinary; D012126:Respiratory Dead Space / Q000502:physiology*; D015656:Respiratory Mechanics / Q000502:physiology; D056152:Respiratory Rate; D013045:Species Specificity