Episodios de hipoxemia en RN en ventilación mecánica

Enero 2009

 

 

Targeted Minute Ventilation and Tidal Volume in an animal model of acute changes in lung mechanics and episodes of hypoxemia

 

Nelson Claure, Cleide Suguihara, Jinghong Peng, Dorothy Hehre, Carmen D’Ugard , Eduardo Bancalari

 

Division of Neonatology, Department of Pediatrics, University of Miami Miller School of Medicine, Miami, Fla. , USA

 

Neonatology 2009;95:132–140              (hacer click sobre link)

 

 

Abstract

 

Background

 

Acute episodes of hypoxemia in ventilated preterm infants are triggered by changes in ventilation, lung volume (LV) and respiratory system compliance (C RS ) that are not prevented by conventional synchronized intermittent mandatory ventilation (SIMV).

 

Objective

 

To assess in a rabbit model of episodic hypoxemia the individual and combined efficacy of targeted tidal volume (V T ) and minute ventilation (V’ E ) by automatic adjustment of peak inspiratory pressure (PIP) and ventilator rate, respectively. Methods: Six young New Zealand white rabbits were ventilated with SIMV, targeted V T , targeted V’ E , and combined targeted V’ E + V T in random sequence. Hypoxemia episodes were induced by apnea alone or by apnea combined with a reduction in LV and C RS . Apnea was induced by a bolus of propofol. The reduction in LV and C RS was induced by chest compression with a cuff. PaO 2 and PaCO 2 were measured continuously by an indwelling arterial electrode. 

 

Results

 

During SIMV, apnea caused a decrease in ventilation and PaO 2 . This was attenuated during targeted V’ E and targeted V’ E + V T . Apnea plus a reduction in LV and C RS caused a greater decrease in ventilation and PaO 2 during SIMV. These changes were attenuated during targeted V T and targeted V’ E . The attenua tion was more pronounced during targeted V’ E + V T .  

 

Conclusion:

 

In this animal model, targeted V’ E was effective in reducing hypoxemia caused by apnea. When apnea was accompanied by a reduction in LV and C RS , the combined adjustment of PIP and ventilator rate was more effective than each individually. This combined strategy may be effective in ameliorating acute episodes of hypoxemia in preterm infants but this remains to be proven.