Minimal Positive End-Expiratory Pressure (PEEP) May be “Best PEEP”

doi:10.1378/chest.93.5.1020

Chest

Volume 93, Issue 5, May 1988, Pages 1020-1025

https://doi.org/10.1378/chest.93.5.1020 Get rights and content

In the absence of clinical trials, positive end-expired pressure (PEEP) has been accepted as efficacious for treatment of postoperative decreases in arterial oxygen tension (FaO₂) from a variety of causes including adult respiratory distress syndrome (ARDS). PEEP is thought to increase PaO₂ by alveolar recruitment, which in turn, has been hypothesized to play a decisive role in pulmonary recovery One hundred and eighteen patients were followed prospectively, and after development of decreased PaO₂, randomized to receive recruitive PEEP (determined by blood gas criteria) or supportive PEEP (the minimal PEEP required to maintain PaO₂ above 60 mm Hg on .5 inspired O₂ fraction (FIO₂). No prognostic factors were significantly different between the two groups. Recruitive PEEP application in 22 patients yielded a significantly increased incidence of hypotension (55 percent), pneumothorax (20 percent), and death during treatment (27 percent) when compared to the 28 supportive PEEP patients who had no hypotension or pneumothorax and only one death during treatment (4 percent). After PEEP treatment, deaths in each group were similar (19 percent and 15 percent, respectively). We find no evidence that PEEP treatment promotes beneficial outcomes and conclude that recruitment attempts may be harmful.

Section snippets

Patient Selection and Consent

The study was approved by the institution's Human Investigation Committee. All staff surgeons participated in this study. Occasional individual patients were not entered in the study by request Patients with a reservation for postoperative admission to the surgical intensive therapy unit (SIT) were approached preoperatively for enlistment in the study. A minority of those patients granted consent. In addition, all patients in the SIT who were both able to give informed consent and had a PaO₂/FIO

Patient Entry and PEEP Postponement

One hundred and eighteen patients were studied. Fifty-four developed PaO₂/FIO₂ <200 mm Hg and were randomized, 26 to recruitive and 28 to supportive PEEP. Sixty-four patients received neither type of PEEP as their PaO₂/FIO₂ was never less than 200 mm Hg.

Four patients whose PaO₂/FIO₂ <200 were randomized to receive recruitive PEEP but actually received no PEEP at any time. That was because they continually met the following postponement criterion: their respiratory rates remained below 25 per

DISCUSSION

PEEP application frequently does not produce a proportional increase in PaO₂. Instead, as PEEP is added, PaO₂ does not change or decreases slightly. Then, at some critical threshold level of PEEP, PaO₂ improves dramatically.⁹ If ${\dot{Q} \bar{v}}_{A} {\dot{/Q}}_{T}$ is measured at each level of PEEP, a similar pattern is seen. In our experience, when dramatic reduction of ${\dot{Q} \bar{v}}_{A} {\dot{/Q}}_{T}$ occurs, but not before, cardiovascular disturbances are common. We have interpreted those events to indicate sudden inflation of

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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 :
However, several studies did not verify the possible effect of high PEEP on pulmonary complications and even reported an increased risk for ARDS in trauma patients who received high PEEP [10]. In terms of hemodynamics, ventilation with high PEEP might reduce the level of mean arterial pressure (MAP) and promote the development of hypotension in patients without ARDS [11]. Furthermore, a recent RCT did not find any evidence to support the application of high PEEP in ICU patients without ARDS [12].
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 :
The eligible studies recruited in this study were performed between 1975 and 2020. Thirteen of the RCTs came from surgical ICU [29-41], and the rest were extracted from medical ICU [8,42-54]. Eleven RCTs applied low Vt among intervention group [8,30,32,33,36,39,44,46,49,50,53] (Vt ≤ 8 cmH2O).
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.
Pulmonary care of the critically ill
1999, Seminars in Anesthesia
In managing the patient requiring ventilatory support, the clinician must exercise vigilance to avoid unnecessary complications. The most obvious of these include barotrauma (pneumothorax, subcutaneous emphysema), hypovolemic hypotension, pneumonia, hypoventilation, and atelectasis. However, the clinician also must be concerned with more subtle, but nonetheless significant factors, such as oxygen toxicity and volutrauma, that may aggravate underlying lung injury. Additionally, the development of unrecognized dynamic hyperinflation, or auto-PEEP, may compromise the clinician's ability to allow adequate exhalation in the patient receiving mechanical ventilatory support. For these reasons, communication between the physician and the respiratory therapy and nursing personnel who provide care for the mechanically ventilated patient is essential. Attention to the patient's plateau airway pressure, inspired oxygen concentration, and flow mechanics is as necessary to the care of the patient as vital signs, physical examination, and chest roentgenograms.
Mechanical ventilation of patients with acute lung injury
1998, Critical Care Clinics
The passage of 30 years since the initial description of the acute respiratory distress syndrome (ARDS) has brought substantial insight into its epidemiology and pathophysiology, yet the condition continues to be devastating and treatment remains largely supportive. Management of respiratory failure in ARDS typically requires ventilatory assistance. In this arena, advances in our understanding of the pathophysiology of acute lung injury have resulted in modifications of traditional approaches to mechanical ventilation and to the development of novel ventilatory modes and adjunctive measures. Many of these newer techniques remain controversial, few being convincingly studied in adequately powered and controlled randomized clinical trials. This article addresses the current understanding of mechanical ventilation in acute lung injury, focusing on practical issues and emphasizing the relationship to lung structure and pathophysiology.
New concepts and therapies of adult respiratory distress syndrome
1997, Journal of Cardiothoracic and Vascular Anesthesia
'Best' PEEP during one-lung ventilation
1997, British Journal of Anaesthesia
Eight patients were studied under general anaesthesia for elective pulmonary lobectomy to see if intrinsic positive end-expired pressure (PEEPi) would appear or increase in the dependent lung during one-lung ventilation (OLV) or if application of external PEEP equal to individually measured PEEPi would produce better arterial oxygenation, haemodynamic state and oxygen delivery than either zero PEEP (ZEEP) or an external PEEP 5 cm H2O greater than PEEPi. Patients were non-obese, without obstructive airways disease, aged 53-76 yr and ASA < III. They received standardized anaesthesia with fentanyl, 50% nitrous oxide in oxygen and isoflurane; monitoring included radial and fibreoptic pulmonary arterial catheters and intermittent positive pressure ventilation with a tidal volume of 8 ml kg-1, 16 bpm, and an I:E ratio of 1:2. PEEPi was measured during two-lung ventilation (TLV) and OLV, using rapid airway occlusion at end-expiration. There was no PEEPi during TLV, but 2-6 mm Hg of PEEPi appeared during OLV. Applying external PEEP equal to individually measured PEEPi reduced venous admixture and increased PaO2 without a decrease in cardiac index (thus increasing oxygen delivery) compared with ZEEP, but the improvement in pulmonary gas exchange was lost and an additional penalty of reduced cardiac output was imposed when external PEEP was increased to 5 mm Hg above PEEPi.

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Chest

Clinical InvestigationsMinimal Positive End-Expiratory Pressure (PEEP) May be “Best PEEP”

Section snippets

Patient Selection and Consent

Patient Entry and PEEP Postponement

DISCUSSION

Curr Cardiol

Chest

J Thorac Cardiovasc Surg

Lancet

Respiratory intensive care

Anesthesiology

Optimum end-expiratory airway pressure in patients with acute pulmonary failure

N Engl J Med

Ventilatory management of patients with adult respiratory distress symdrome

Sem Respir Med

Mechanical ventilation: physiology and application

Curr Prob Surg

Misapplication of alveolar gas equation

N Engl J Med

Clinical Investigations
Minimal Positive End-Expiratory Pressure (PEEP) May be “Best PEEP”