Premium
Determining optimum inspiratory time during intermittent positive pressure ventilation in surfactant‐depleted cats
Author(s) -
Mammel Mark C.,
Boros Stephen J.,
Bing Dennis R.,
Holloman Keith K.,
Connett John R.
Publication year - 1989
Publication title -
pediatric pulmonology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.866
H-Index - 106
eISSN - 1099-0496
pISSN - 8755-6863
DOI - 10.1002/ppul.1950070407
Subject(s) - medicine , cats , pulmonary surfactant , ventilation (architecture) , intermittent positive pressure ventilation , positive pressure respiration , anesthesia , positive pressure ventilation , peak inspiratory pressure , mechanical ventilation , intensive care medicine , respiratory system , tidal volume , respiratory failure , physics , thermodynamics , mechanical engineering , engineering
This study compares two methods of selecting inspiratory time (Ti) during mechanical ventilation. One selects a standard Ti producing a brief inspiratory pressure plateau (P). The other uses simultaneous pressure, flow and tidal volume (VT) waveforms, generated by a computer‐assisted lung mechanics analyzer, to reduce Ti to the point where Vt ceases to accumulate and flow returns to zero. This method does not produce a pressure plateau (NP). Following saline lung washout, ten intubated, paralyzed surfactant‐depleted cats were ventilated with pressure‐preset infant ventilators at constant measured VT and rates. Five animals were initially ventilated with P (Ti = 0.98±0.02 s) and five with NP (Ti = 0.77±0.10 s). Ti was then varied to produce P or NP by using a four‐period crossover design. All other ventilator variables remained constant. Intravascular pressures, thermodilution cardiac outputs, arterial and mixed venous blood gases and oxygen saturations, airway pressures, Ti, VT, and gas flows were measured; respiratory system mechanics, alveolar‐arterial oxygen gradients, and intrapulmonary shunts were determined for each study period. When P and NP states were compared, only mean airway pressures differed (10.1 vs. 8.9 cmH 2 O; P <0.001). Blood gas values, intravascular pressures, cardiac output, and respiratory system mechanics were all similar. Under the conditions of this study, there was no advantage to prolonging Ti beyond the point where VT ceased to accumulate. Pediatr Pulmonol 1989; 7:223–229 .