Roth 2001.
| Methods | Single centre randomized controlled trial | |
| Participants | 40 consecutive adult patients (intervention 20: control 20) with healthy lungs who underwent brain surgery. Included patients were those who required controlled ventilation and who were expected to show spontaneous breathing efforts during the 1st 24 hours after ICU admission. Patients with central depression of breathing drive expected to last > 24 hours as well as patients with mechanical or neural damage making spontaneous breathing efforts impossible were excluded. Setting: Germany, university hospital, 18 bed ICU |
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| Interventions | Intervention: Automode on Siemens Servo ventilator 300. Initial stabilisation period on PCV for 20 minutes after ICU admission. Automode was activated by automatically switching from PCV to PSV in cases of repeated triggering of the ventilator and back in cases of apnoea of more than 12 seconds. Patients were considered ready for extubation when there was stable spontaneous breathing without switching back to controlled ventilation. Control: SIMV with an initial stabilisation period on PCV for 20 minutes after ICU admission. Mandatory frequency was initially reduced by 2 breaths/min if the ventilator indicated triggering by the patient. Mandatory frequency was further decreased in cases of stability and/or an increase in minute ventilation over the pre‐set alarms. If MV dropped below the pre‐set alarms, the mandatory rate was increased again. Adjustments were made by the nurses, supervised by the physicians. Manual switching to PSV was done in cases of stable spontaneous breathing. Alarm levels for MV were set to 8‐% and 120% of values measured in the stabilisation phase. In both groups, pressure levels were adjusted within a range of 10‐15 cmH2O to reach a VT of 10 mL/kg body weight. Respiratory rate adjusted to reach normoventilation. I:E ratio set to 1:2, FiO2 0.35‐40 (PaO2 90 mmHg), PEEP 5 cmH2O. PSV was adjusted to the same inspiratory pressure used during PCV. PS, PEEP and FiO2 were kept constant until extubation. Patients were considered ready for extubation when there was stable spontaneous breathing without the need for mandatory background frequency. |
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| Outcomes | Total weaning time Number of manipulations Respiratory and circulatory parameters measured at randomization (T0), 20 minutes after the 1st spontaneous breathing activity (T20), 2 hours after T20 (T140), before extubation (Tex), and 1 hour after extubation (Tpost) Variability of ventilation (range of PaCO2 levels) |
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| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Not reported |
| Allocation concealment (selection bias) | Unclear risk | Not reported |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | No attrition, no missing outcome data |
| Selective reporting (reporting bias) | Low risk | All pre‐specified outcomes are reported |
| Other bias | Low risk | No other sources of bias detected |
| Blinding of participants and personnel (performance bias) All outcomes | High risk | Not possible to blind personnel |
| Blinding of outcome assessment (detection bias) All outcomes | Unclear risk | Unable to confirm if outcome assessors were also involved in the daily care of patients |