Strickland 1993.
| Methods | Single centre pilot randomized controlled trial | |
| Participants | 17 patients (9 computer; 7 physician weaning group) judged ready to wean by his/her attending physician and meeting the following criteria: pH ≥ 7.30 and ≤ 7.50, PaCO2 ≥30 and ≤ 50 mmHg, SaO2 ≥ 90% while on SIMV with a rate of 6‐10, VT of 10‐15 mL/kg, PS 20 cmH2O and FiO2 ≤ 0.4, negative inspiratory force ≤ ‐ 20 cmH2O, forced vital capacity ≥ 10 mL/kg, stable haemodynamics and renal function, parenteral or enteral feeding, no ileus, normal electrolytes, infection controlled with antibiotics with oral temperature ≤ 37.7C. Post operative patients were excluded unless had been on ventilator for ≥ 3 days. Patients requiring PEEP had to be weaned of (PEEP) prior to entering the study. Setting: United States, 3 pulmonary physicians were involved in patient care either in a consultative or attending role |
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| Interventions | Intervention: modification of Puritan Bennett 7200 to allow direct control of the ventilator settings by an external PC‐compatible computer that monitored the patient and ventilator data through the serial digital outputs of the pulse oximeter and ventilator. Weaning started at SIMV rate 6, PS 20 cmH2O, FiO2 ≤ 0.4, and VT 10‐15 mL/kg. The computer sampled respiratory rate and SpO2 every 5 minutes, and calculated a moving average of VT using the average of the last 5 time 1 minute VT samples. To proceed with weaning the respiratory rate had to be ≥ 8 and ≤ 30 and VT ≥ 5 mL/kg (ideal body weight based on height). The system alarmed if SpO2 was <90% but no weaning changes were made by the computer based on SpO2. The computer decreased the SIMV rate by 2 every hour until a rate of 2 was reached. The computer then decreased the PS by 2 cmH2O every hour as long as the VT and respiratory rate limits were met. The weaning process was complete when the SIMV rate was 2 and the PS 5 cmH2O. If the 5‐minute samples of respiratory rate or VT were not within acceptable limits, the computer increased the level of ventilator support. Control: weaning progressed through SIMV rate and PS reduction as judged appropriate by the patient's physician |
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| Outcomes | Weaning success Time to wean Number of ABG samples Number of minutes per hour respiratory rate and VT were outside acceptable limits |
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| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Random number table |
| Allocation concealment (selection bias) | Low risk | Sealed envelopes |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | Attrition reported, 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 | Impossible to blind personnel |
| Blinding of outcome assessment (detection bias) All outcomes | Unclear risk | Unable to confirm if outcome assessors were also involved in daily patient care |