POSITIVE END-EXPIRATORY PRESSURE IN WEANING PATIENTS FROM CONTROLLED VENTILATION: A Prospective Randomised Trial

doi:10.1016/S0140-6736(75)90719-9

The Lancet

Volume 306, Issue 7938, 18 October 1975, Pages 725-729

https://doi.org/10.1016/S0140-6736(75)90719-9 Get rights and content

Abstract

Twenty-five patients in acute respiratory failure were randomised to receive either 5 cm of positive end-expiratory pressure (P.E.E.P.) or no-P.E.E.P. while weaning from controlled ventilation. The use of P.E.E.P. resulted in a significant reduction in the increase in alveolar-arterial oxygen tension gradient (AaDO₂¹) which occurred in the group of patients who were converted from controlled ventilation to spontaneous ventilation without P.E.E.P. Patients who weaned without P.E.E.P. had a mean increase in AaDO₂¹ of 102±35 mm Hg S.E. while those who weaned with P.E.E.P. had a mean increase of only 10±22 mm Hg (P<0·03). The use of P.E.E.P. was also associated with a significant improvement in the vital capacity and the maximum inspiratory force. Patients who weaned with P.E.E.P. had an increase in vital capacity of 258±108 ml (P<0·05) and an increase in inspiratory force of -15±5 cm H₂O (_P<0·01), while patients who weaned without P.E.E.P. did not have significant changes in these measurements. The use of P.E.E.P. during weaning may be helpful in patients who fail to wean because of the development of hypoxæmia due to rapid alveolar collapse, since P.E.E.P. appears to minimise the increase in intrapulmonary right-to-left shunt which normally occurs during weaning from controlled ventilation.

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Cited by (37)

Higher PEEP versus lower PEEP strategies for patients in ICU without acute respiratory distress syndrome: A systematic review and meta-analysis
2022, Journal of Critical Care
Citation Excerpt :
Among the studies presented in Supplementary Table 1, in the high PEEP group, PEEP ranged from 5 to 30 cm H2O, while in the low PEEP group, PEEP ranged from 0 to 10 cm H2O. Ten studies used ZEEP (defined as 0 cm H2O PEEP) as a comparative group, and most of them were published earlier [3,10,17,19-24,29]. Patients in ICU requiring PEEP were medical patients (including those with ARF, trauma, neurogenic pulmonary edema (NPE), etc.), postoperative patients (most of whom had undergone cardiac surgery) or mixed patients (containing medical and postoperative patients), and the number of participants ranged from 15 to 969.
To evaluate the effects of high and low levels of PEEP on ICU patients without ARDS.
We searched public databases (including PubMed, EMBASE, Cochrane Library and Clinicaltrial.gov). The Cochrane Risk of Bias Assessment tool was used to evaluate the quality of the included studies.
We included 2307 patients from 24 trials. Although no significant difference was found between high and low PEEP applications in in-hospital mortality (risk ratio[RR] 0.98, 95% confidence interval[CI] [0.81, 1.19], P = 0.87), high PEEP indeed decreased the incidence of ARDS, hypoxemia, and increased the level of PaO₂/FIO₂. In addition, although the overall results did not reveal any advantages of high PEEP in terms of secondary outcomes regarding 28-day mortality, the duration of ventilation, atelectasis, pulmonary barotrauma, hypotension, and so forth, the subgroup analysis concerning the level of low PEEP (ZEEP or not) and patient type (postoperative or medical ones) yielded different results. The TSA results suggested that more RCTs are needed.
Although ventilation with high PEEP in ICU patients without ARDS may not reduce in-hospital mortality, the decreased incidences of ARDS and hypoxemia and the improvement in PaO₂/FIO₂ were found in the high PEEP arm.
Effect of different levels of PEEP on mortality in ICU patients without acute respiratory distress syndrome: systematic review and meta-analysis with trial sequential analysis
2021, Journal of Critical Care
Citation Excerpt :
And eight of twenty-seven RCTs used P/F ratio or SpaO2 to set PEEP between these two groups [8,29,30,43,44,47,48,53]. The rest of studies set PEEP according to predefined protocol [31-35,37-42,45,46,49-52,54]. Regarding the risk of bias of individual RCTs, six studies were judged as low risk of bias [8,30,34,39,41,46].
To determine whether higher positive end- expiratory pressure (PEEP) could provide a survival advantage for patients without acute respiratory distress syndrome (ARDS) compared with lower PEEP.
Eligible studies were identified through searches of Embase, Cochrane Library, Web of Science, Medline, and Wanfang database from inception up to 1 June 2021. Trial sequential analysis (TSA) was used in this meta-analysis.
Twenty-seven randomized controlled trials (RCTs) were identified for further evaluation. Higher and lower PEEP arms included 1330 patients and 1650 patients, respectively. A mean level of 9.6±3.4 cmH₂O was applied in the higher PEEP groups and 1.9±2.6 cmH₂O was used in the lower PEEP groups. Higher PEEP, compared with lower PEEP, was not associated with reduction of all-cause mortality (RR 1.03; 95% CI 0.91–1.18; P =0.627), and 28-day mortality (RR 1.07 ; 95% CI 0.92–1.24; P =0.365). In terms of risk of ARDS (RR 0.43; 95% CI 0.24–0.78; P =0.005), duration of intensive care unit (MD -1.04; 95%CI-1.36 to −0.73; P < 0.00001), and oxygenation (MD 40.30; 95%CI 0.94 to 79.65; P = 0.045), higher PEEP was superior to lower PEEP. Besides, the pooled analysis showed no significant differences between groups both in the duration of mechanical ventilation (MD 0.00; 95%CI-0.13 to 0.13; P = 0.996) and hospital stay (MD -0.66; 95%CI-1.94 to 0.61; P = 0.309). More importantly, lower PEEP did not increase the risk of pneumonia, atelectasis, barotrauma, hypoxemia, or hypotension among patients compared with higher PEEP. The TSA analysis showed that the results of all-cause mortality and 28-day mortality might be false-negative results.
Our results suggest that a lower PEEP ventilation strategy was non-inferior to a higher PEEP ventilation strategy in ICU patients without ARDS, with no increased risk of all-cause mortality and 28-day mortality. Further high-quality RCTs should be performed to confirm these findings.
Modalities of spontaneous breathing trials
2001, Reanimation
Trials comparing alternative weaning modes and discontinuation assessments
2001, Chest
Citation Excerpt :
The sample size of the eight randomized studies of discontinuation assessment strategy modes varied from 18 to 526. Three of the studies enrolled > 100 patients (Table 1).1516171819202122 The largest studies2122 were methodologically strong, reporting the method of randomization and weaning, extubation, and reintubation criteria.
We identified 16 randomized controlled trials (RCTs) of methods for weaning patients from mechanical ventilation, 8 of which were trials of discontinuation assessment strategies, 5 of which were trials of stepwise reduction in mechanical ventilatory support, and 3 of which were trials comparing alternative ventilation modes for weaning periods lasting < 48 h. We found that different thresholds for deciding when a patient is ready for a trial of spontaneous breathing, different criteria for a successful trial, and different thresholds for extubation may overwhelm the impact of alternative ventilation strategies. Nevertheless, the results of these studies suggest the possibility that multiple daily T-piece weaning or pressure support may be superior to synchronized intermittent mandatory ventilation. Other RCTs suggest that early extubation with the back-up institution of noninvasive positive-pressure ventilation as needed may be a useful strategy in selected patients.
Comparison of pressure and flow triggering systems during continuous positive airway pressure
1994, Chest
Study objective: Compare the inspiratory work of breathing (WOB_I) during pressure triggering (PT), and flow triggering (FT) using two microprocessor ventilators.
Design: A randomized, crossover comparison of triggering strategies and ventilators was used.
Setting: Surgical intensive care unit.
Patients: Ten patients recovering from acute respiratory failure (eight men, two women; mean age, 48 ± 12 years) breathing on continuous positive airway pressure (CPAP) of 5 cm H₂O were studied.
Interventions: Patients were randomly assigned to either receive 5 cm H₂O CPAP via one of two units (Hamilton Veolar or Puritan Bennett 7200ae) using either PT or FT. Each patient had 30-min trials using the following: (1) Veolar FT; (2) Veolar PT; (3) 7200ae FT; and (4) 7200ae FT.
Measurements and results: During each trial period, work of breathing (WOB) and pressure time product (PTP) were measured using a respiratory monitor (Bicore CP-100). All patients were placed in semi-Fowler position and esophageal balloons were inserted and their position confirmed using the occlusion technique. Continuous measurements of peak negative pressure during inspiration, tidal volume (VT), minute ventilation (VE), respiratory frequency (f) were accomplished with a flow transducer at the proximal airway. FT with the 7200ae was superior to PT as measured by both the WOB (0.58 ± 0.3 vs 0.84 ± 0.2 J/L, p<0.01) and PTP (148 ± 50 vs 206 ± 41 cm H₂O/s/min, p,0.05). FT with the Veolar was also superior to PT with respect to the WOB (0.53 ± 0.2 vs 0.93 ± 0.2 J/L, p<0.01) and PTP (140 ± 39 vs 229 ± 46 cm H₂O/s/min, p<0.05).
Conclusion: FT reduces the WOB compared with PT, regardless of the ventilator used. The reduction in WOB during FT is related to improved responsiveness and changes in the posttrigger phase.
Positive end-expiratory pressure vs T-piece: Extubation after mechanical ventilation
1991, Chest
Because T-piece breathing may impair oxygenation, the best airway pressure from which to extubate ventilated patients is controversial. We compared the effects of extubation after 1 h of either CPAP 5 and T-piece/ZEEP. Once weaned from mechanical ventilation and breathing spontaneously, 106 patients were randomized to 1 h CPAP or 1 h T-piece/ZEEP, following which patients were extubated and mask O₂ administered. No significant difference existed between groups in age, sex, HR, BP, Flo₂, PaCO₂ or PaO₂. However, P(A-a)O₂ was significantly greater at 120 min in the CPAP group. Within the CPAP group, P(A-a)O₂ was also significantly worse at 120 vs 0 min. Nineteen T-piece patients showed improved P(A-a)O₂ at 120 min compared with only ten CPAP patients. Three CPAP and two T-piece patients subsequently required reintubation. This study demonstrates that use of a T-piece does not impair arterial oxygenation and may in fact be superior to direct extubation from CPAP 5.

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POSITIVE END-EXPIRATORY PRESSURE IN WEANING PATIENTS FROM CONTROLLED VENTILATION: A Prospective Randomised Trial

Abstract

New Engl. J. Med.

ibid.