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Nasal SIMV After Extubation
Randomized Trial of Nasal Synchronized Intermittent Mandatory Ventilation (nSIMV) Compared with Continuous Positive Airway Pressure (CPAP) After Extubation of Very Low Birth Weight Infants. Pediatrics 2001; 107(4):638-41.
Fifty-four infants of < 1250 gm birth weight who were due to be extubated before 6 weeks of age, were eligible once they were receiving < 35% oxygen and were on a ventilator rate of < 18 breaths per minute. Extubation was performed following intravenous loading with aminophylline, after a successful trial of 12 hours of endotracheal SIMV at a rate of 8. Infants were randomized to either nasal CPAP at 6 cm H20 or nSIMV after extubation. The nSIMV was commenced at a rate of 12 bpm with a pressure on the ventilator set to achieve a delivered pressure of at least 12 cm H20 and a peak end-expiratory pressure of 6 cm H20. Continuous recording for diagnosis of apnea was performed for 72 hours after extubation. Objective criteria for failure of extubation were: PaCO2 > 70; FIO2 > 0.70; or severe recurrent apnea (> 2 apneas requiring intermittent positive-pressure ventilation in 24 hours, or >6 apneas >20 seconds per day).
Results: The mean birth weight (831 +/- 193 gm) and EGA (26.3 +/- 1.8 weeks) did not differ between groups. The mean age at extubation was 7.6 +/- 9.7 days (range 1 - 40 days). The nSIMV group had a lower incidence of failed extubation (4 of 27) compared with the CPAP group (12 of 27). This was attributable to both a decreased incidence of apnea and a decreased incidence of hypercarbia in the nSIMV group. There was no increase in the incidence of abdominal distension or feeding intolerance in the nSIMV group.
Comment. I really like this approach to achieving successful extubation in a group of babies many of us had previously considered "too small" for extubate. The extubation criteria used in this study were fairly aggressive, and the median time to extubation was only 3 days in each group. If you are going to try and replicate these results in your own practice, please be aware that the type of ventilator used for the nSIMV was the InfantStar ventilator which uses a Starsync capsule applied to the infant’s abdomen to sense spontaneous breaths. I doubt whether ventilators which provide SIMV by using a pneumotach to detect air flow changes would be able to synchronize as well
with nasal prong ventilation. Poor synchronization might be expected to cause an increase in abdominal distension and feeding intolerance.