Abstract
IntroductionReduction of automatic pressure support based on a target respiratory frequency or mandatory rate ventilation (MRV) is available in the Taema-Horus ventilator for the weaning process in the intensive care unit (ICU) setting. We hypothesised that MRV is as effective as manual weaning in post-operative ICU patients.MethodsThere were 106 patients selected in the post-operative period in a prospective, randomised, controlled protocol. When the patients arrived at the ICU after surgery, they were randomly assigned to either: traditional weaning, consisting of the manual reduction of pressure support every 30 minutes, keeping the respiratory rate/tidal volume (RR/TV) below 80 L until 5 to 7 cmH2O of pressure support ventilation (PSV); or automatic weaning, referring to MRV set with a respiratory frequency target of 15 breaths per minute (the ventilator automatically decreased the PSV level by 1 cmH2O every four respiratory cycles, if the patient's RR was less than 15 per minute). The primary endpoint of the study was the duration of the weaning process. Secondary endpoints were levels of pressure support, RR, TV (mL), RR/TV, positive end expiratory pressure levels, FiO2 and SpO2 required during the weaning process, the need for reintubation and the need for non-invasive ventilation in the 48 hours after extubation.ResultsIn the intention to treat analysis there were no statistically significant differences between the 53 patients selected for each group regarding gender (p = 0.541), age (p = 0.585) and type of surgery (p = 0.172). Nineteen patients presented complications during the trial (4 in the PSV manual group and 15 in the MRV automatic group, p < 0.05). Nine patients in the automatic group did not adapt to the MRV mode. The mean ± sd (standard deviation) duration of the weaning process was 221 ± 192 for the manual group, and 271 ± 369 minutes for the automatic group (p = 0.375). PSV levels were significantly higher in MRV compared with that of the PSV manual reduction (p < 0.05). Reintubation was not required in either group. Non-invasive ventilation was necessary for two patients, in the manual group after cardiac surgery (p = 0.51).ConclusionsThe duration of the automatic reduction of pressure support was similar to the manual one in the post-operative period in the ICU, but presented more complications, especially no adaptation to the MRV algorithm.Trial RegistrationTrial registration number: ISRCTN37456640
Highlights
Reduction of automatic pressure support based on a target respiratory frequency or mandatory rate ventilation (MRV) is available in the Taema-Horus ventilator for the weaning process in the intensive care unit (ICU) setting
pressure support ventilation (PSV) levels were significantly higher in MRV compared with that of the PSV manual reduction (p < 0.05)
Many factors need to be considered for weaning success: an adequate level of consciousness and respiratory drive; an adequate gas exchange with progressive decrement of the inspiratory and expiratory respiratory pressures; preserved respiratory muscle function and ANOVA: analysis of variance; BPM: breaths per minute; CI: confidence interval; CPM: cycles per minute; FiO2: fraction of inspired oxygen; ICU: intensive care unit; interquartile ranges (IQR): interquartile range; MRV: mandatory rate ventilation; positive end expiratory pressure (PEEP): positive end-expiratory pressure; PS max: pressure support maximum; PSV: pressure support ventilation; RR: respiratory rate; SD: standard deviation; SpO2: arterial oxygen saturation; TV: tidal volume
Summary
Reduction of automatic pressure support based on a target respiratory frequency or mandatory rate ventilation (MRV) is available in the Taema-Horus ventilator for the weaning process in the intensive care unit (ICU) setting. The success of the weaning depends more on the patients' ventilatory capability than on the demand of the patient In this manner, many factors need to be considered for weaning success: an adequate level of consciousness and respiratory drive; an adequate gas exchange with progressive decrement of the inspiratory and expiratory respiratory pressures; preserved respiratory muscle function and ANOVA: analysis of variance; BPM: breaths per minute; CI: confidence interval; CPM: cycles per minute; FiO2: fraction of inspired oxygen; ICU: intensive care unit; IQR: interquartile range; MRV: mandatory rate ventilation; PEEP: positive end-expiratory pressure; PS max: pressure support maximum; PSV: pressure support ventilation; RR: respiratory rate; SD: standard deviation; SpO2: arterial oxygen saturation; TV: tidal volume (page number not for citation purposes). The level of assistance can be gradually decreased until it only compensates for the additional work imposed by the endotracheal tube and the demand valve of the ventilator, at which time tracheal extubation can be performed It can be used in association with positive end expiratory pressure (PEEP) and monitoring. Studies have shown that the duration of mechanical ventilation depends on a systematic approach in the weaning period for reducing the level of assistance and testing the possibility to resume spontaneous breathing [5,11,12]
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