Synchronous intermittent mandatory ventilation modes compared with patient triggered ventilation during weaning.

Abstract

The efficacy of combining rate and pressure reduction during weaning by synchronous intermittent mandatory ventilation (SIMV) were compared with weaning by patient triggered ventilation (PTV) (pressure reduction alone) in two randomised trials. Regardless of ventilation mode, pressure was reduced to the same level according to the size of the infant. In the first trial, the SIMV rate was also reduced progressively to a minimum of 20 breaths/minute, and in the second to five breaths/minute. Forty premature infants aged 15 days of age or less were randomly allocated into each trial. No significant differences were found in the first trial between ventilation modes in either the duration of weaning or the number of infants in whom weaning failed. In the second trial, the duration of weaning was shorter by PTV than by SIMV (median 24 hours, range 7-432 v 50 hours, range 12-500; p<O0O5); weaning failed in two infants in the PTV group and in five in the SIMV group. It is concluded that weaning by a combination of pressure and rate reduction, such as can be achieved during SIMV, offers no significant advantage over pressure reduction alone. (Arch Dis Child 1995; 72: F188-F190) Keywords: synchronous intermittent mandatory ventilation, patient triggered ventilation, weaning.During both patient triggered ventilation (PTV) and synchronous intermittent mandatory ventilation (SIMV), the infant is able to trigger positive pressure inflations, providing respiratory efforts exceed the critical trigger level. In SIMV, however, the number of 'supported' breaths is controlled by the SIMV rate: thus if the infant breathes at a rate of 80 breaths per minute and the SIMV rate is 20 breaths per minute, the maximum number of triggered breaths is 20. A randomised weaning trial comparing PTV and SIMV failed to show a clear advantage of weaning by pressure reduction (PTV) over weaning by rate reduction (SIMV), but neither regimen was universally successful.1Those data indicate that further investigation of weaning strategies is necessary; one possible approach would be to decrease both rate and pressure. MethodsPreterm infants of less than 35 weeks' gestation and aged 15 days or under were recruited in the recovery stage of their initial respiratory illness into two consecutive weaning studies. All infants were weaned from the ventilator according to the routine protocol2 until a ventilator rate of 40 breaths/minute was reached. At that stage, all infants were given theophylline or aminophylline (4 mg/kg/day) and transferred to an SLE 2000 ventilator at the same ventilator settings. Random selection to either PTV or SIMV then took place by drawing a card from a sealed envelope. After a 30 minute period of stabilisation, the ventilator was switched over to provide either PTV or SIMV, as indicated by the randomisation card. The ventilator settings were unchanged unless changes were needed to achieve an inspiratory time of 0 3 seconds3 and a positive end expiratory pressure (PEEP) of 3 cm H20 (0-294 kPa), which were used throughou...

Oxygen cost of breathing and weaning process in newborn infants

“…Only three trials published in two reports [6,7] have compared PTV and SIMV during weaning periods. No major differences were observed between the two modes in terms of failure or duration of weaning, except in one trial in which duration of weaning was significantly shorter with PTV [7]. However, in theses studies, no V 'O 2 or work of breathing measurements were performed.…”

“…Inspiratory pressure support, used during the weaning process in adult intensive care, may be useful in reducing the work of breathing [2]. Recent data have shown that patient triggered ventilation (PTV) decreases the work of breathing in premature neonates [3], and that PTV can be used as a weaning ventilatory mode [4][5][6][7]. We hypothesized that the increase in V'O 2 observed at the time of weaning in some newborn infants could be reduced by using PTV.…”

Mechanical Ventilation of the Premature Neonate

“…[13][14][15][16] There have also been several small short-term clinical trials of PC-SIMV versus PC-IMV or PC-CMV versus PC-IMV. [13][14][15][16][17][18][19][20] Overall, in neonates, PC-CMV has shown less V T variability, shorter weaning time, lower WOB, and better blood gas values and vital signs than PC-SIMV, and lower WOB and shorter duration of weaning than PC-IMV. 15 A recent Cochrane meta-analysis 21 evaluated 14 RCTs and compared differences in outcomes with patient-triggered ventilation versus non-patient-triggered ventilation (eg, PC-IMV).…”

“…7,[17][18][19][20][21][22] It may, however, be more important to choose the correct ventilation strategy, once the ventilation mode is chosen. There is evidence that optimization of the lung volume is key to lung protection, regardless of what ventilation mode is used.…”

Comparação entre ventilação mandatória intermitente e ventilação mandatória intermitente sincronizada com pressão de suporte em crianças

“…22 Four studies that assessed extubation failure in the context of a comparison between SIMV with IMV were subjected to a meta-analysis published in 2006, 23 which did not detect any significant effect on this variable from using one or other of the modes. In order to compare assist-control with SIMV in terms of extubation failure, two studies were selected for meta-analysis 20,21 and once more there was no significant difference between the two modes. In common with these findings, we did not observe any differences between our two groups in terms of the frequency of extubation failure.…”