Intensive Alveolar Recruitment Protocol After Cardiac Surgery

Comparison of Two Protective Mechanical Ventilation Strategies After Cardiac Surgery: Aggressive Versus Moderate Alveolar Recruitment Strategies

The purpose of this study was to evaluate prospectively the impact of two protective mechanical ventilation strategies, both using low tidal volume ventilation (6 mL/kg/ibw) after cardiac surgery. The study selected patients presenting signals of deficient gas exchange (PaO2/FIO2 < 250 at a PEEP [positive end expiratory pressure] of 5 cmH2O) in the immediate post-operative period. An aggressive alveolar recruitment protocol applying opening pressures of 45 cmH2O, followed by ventilation with PEEP = 13 cmH2O, was compared to the standard alveolar recruitment protocol of the institution, where an opening pressure of 20 cmH2O in the airways is followed by ventilation with PEEP = 8 cmH2O. After a stabilizing period of four hours of controlled mechanical ventilation, the patients followed the routine weaning protocol and physiotherapy protocol of the institution.

Study Overview

• Status: Completed
• Conditions: Acute Lung Injury; Cardiac Disease; Ventilator Induced Lung Injury
• Intervention / Treatment: Other: Intensive Alveolar Recruitment; Other: Moderate Alveolar Recruitment

Detailed Description

The postoperative period of cardiac surgery is associated with the development of pulmonary complications. Functional residual capacity can be reduced up to 50% and pulmonary volumes may be decreased until three months after surgery.

Lung injury is the result of pulmonary inflammation (activated by cardiopulmonary bypass, the surgical procedure itself and ischemia-reperfusion injury), the adopted mechanical ventilation strategy and a consequence of previous cardiac and/or pulmonary dysfunction.

The use of protective mechanical ventilation strategies with low tidal volumes since the immediate postoperative period, or since the operating room, has been shown to attenuate and prevent lung injury in previous studies selecting with high-risk patients.

A more complex topic, however, has been the proof of the additional benefit of alveolar recruitment maneuvers during the brief period of mechanical ventilation after surgery. While the experimental evidence suggests that the use of an open lung approach could minimize the shearing forces in the lung parenchyma, enhancing the protection afforded by low tidal volume ventilation, innumerous concerns about the hemodynamic side effects, and the possibility of barotrauma have prevented the routine use of intensive alveolar recruitment protocols. Another matter of concern is the net efficacy of a recruitment maneuver applied in the post-operative period, instead of the intra-operative period.

Thus, this study compared the impact of two protective mechanical ventilation strategies, both using low-tidal volume ventilation (6 mL/kg/ibw) after cardiac surgery, in a selective population of patients presenting signals of deficient gas exchange (PaO2/FIO2 < 250 at a PEEP of 5 cmH2O) in the immediate post-operative period. In a previous study at this institution, this subgroup of patients was shown to be at higher risks of postoperative pulmonary complications.

During the short period of controlled mechanical ventilation after the patient arrival from the operating theater, an aggressive alveolar recruitment protocol applying opening pressures of 45 cmH2O, followed by ventilation with PEEP = 13 cmH2O, was compared to the standard alveolar recruitment protocol of the institution, where an opening pressure of 20 cmH2O in the airways is followed by ventilation with PEEP = 8 cmH2O. After an stabilizing period of four hours of controlled mechanical ventilation, the patients followed the routine weaning protocol and physiotherapy protocol of the institution.

Our hypothesis was that the aggressive alveolar recruitment strategy might help in the reversal of collapse created during the surgery and short term mechanical ventilation during anesthesia and patient transportation. Previous studies have shown that this effect may extend to the post-extubation period, impairing lung function for a few days.

Thus, we tested if the effect of an aggressive alveolar recruitment protocol was translated in a better lung compliance, better gas exchange, and fewer pulmonary complications in the post-operative periods (this latter was our primary outcome). Analysis of the length of stay was also scrutinized, consisting in our secondary outcome. All hemodynamic complications was reported, since we also anticipated that events of hemodynamic impairment might be more frequent in the aggressive recruitment arm, eventually obscuring the expected benefits .

• Study Type: Interventional
• Enrollment (Actual): 320
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Brazil
  • São Paulo, Brazil
    • Instituto do Coração (Incor) - University of São Paulo

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 80 years (ADULT, OLDER_ADULT)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Immediate postoperative period of myocardial revascularization and/or heart valve surgery (aortic and/or mitral)
• Age > 18 years and < 80 years
• No previous pulmonary disease
• Left ventricular ejection fraction > 35%
• Body mass index < 40 kg/m2
• Oxygen index (PaO2/FiO2) < 250
• Corrected volemic status (negative raising legs mean arterial pressure [MAP] variation < 10%)
• Written inform consent

Exclusion Criteria:

• MAP (mean arterial pressure) < 60 mmHg
• Noradrenaline > 2 micrograms/Kg/min
• Acute arrhythmias
• Blooding associated to hemodynamic instability
• Need of re-surgery and/or mechanical circulatory assistance
• Suspicion of neurological alteration
• Chest tube with persistent air leak

Study Plan

How is the study designed?

Design Details

• Primary Purpose: TREATMENT
• Allocation: RANDOMIZED
• Interventional Model: PARALLEL
• Masking: TRIPLE

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
EXPERIMENTAL: Intensive Alveolar Recruitment; Recruitment with opening pressures of 45 cmH2O in the airways.	Other: Intensive Alveolar Recruitment; Recruitment with opening pressures of 45 cmH2O in the airways, followed by ventilation with PEEP = 13 cmH2O, during 4 hours of protective mechanical ventilation with tidal volume (VT) = 6 mL/kg/pbw.
ACTIVE_COMPARATOR: Moderate Alveolar Recruitment; Recruitment with opening pressures of 20 cmH2O in the airways.	Other: Moderate Alveolar Recruitment; Recruitment with opening pressures of 20 cmH2O in the airways, followed by ventilation with PEEP = 8 cmH2O, during 4 hours of protective mechanical ventilation with VT = 6 mL/kg/pbw.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Severity of Pulmonary Complications in the Post-operative Period	Score of pulmonary complications adapted from previous publications, with 5 degrees, where the higher one means death before hospital discharge, degree (4) means the need of mechanical ventilation for more than 48 hours after surgery or after reintubation, degree (3) means pneumonia or intense noninvasive ventilation need, degree (2) means hypoxemia and abnormal lung findings, degree 1 means simple atelectasis and degree (0) means no complication. The comparison used this ordinal variable, representing the highest score achieved during the post-operative period. The comparison between arms was made through the Mann-Whitney U test. Data shown are percentage of participants with pulmonary complications grade ≥ 3.	Participants were followed for the duration of hospital stay.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Length of ICU Stay	Days since surgery until ICU discharge, analyzed through Kaplan-Meyer curves (log-Rank test), where the time to event is the time of discharge from the ICU. The censoring was performed at 28 days. Patients dying before leaving the ICU were censored as not discharged from ICU at day 28.	From the day of surgery up to ICU discharge, maximum censoring at day 28 after surgery
Length of Hospital Stay	Days since surgery until Hospital discharge, analyzed through Kaplan-Meyer curves (log-Rank test), where the time to event is the time of discharge from the Hospital. The censoring was performed at 28 days. Patients dying before leaving the Hospital were censored as not discharged from Hospital at day 28.	From the day of surgery up to Hospital discharge, maximum censoring at day 28 after surgery
Incidence of Barotrauma	Confirmed by X-ray. Test with logistic regression	Five days after surgery
Hospital Mortality	Deaths occurred during hospital stay, tested with logistic regression.	From the day of surgery up to Hospital discharge or death, with no maximum censoring.

Collaborators and Investigators

• Sponsor: University of Sao Paulo
• Collaborators: InCor Heart Institute
• Investigators: Study Director: Marcelo BP Amato, PhD, University of São Paulo

Publications and helpful links

General Publications

• Costa Leme A, Hajjar LA, Volpe MS, Fukushima JT, De Santis Santiago RR, Osawa EA, Pinheiro de Almeida J, Gerent AM, Franco RA, Zanetti Feltrim MI, Nozawa E, de Moraes Coimbra VR, de Moraes Ianotti R, Hashizume CS, Kalil Filho R, Auler JO Jr, Jatene FB, Gomes Galas FR, Amato MB. Effect of Intensive vs Moderate Alveolar Recruitment Strategies Added to Lung-Protective Ventilation on Postoperative Pulmonary Complications: A Randomized Clinical Trial. JAMA. 2017 Apr 11;317(14):1422-1432. doi: 10.1001/jama.2017.2297.

Study record dates

Study Major Dates

• Study Start: December 1, 2011
• Primary Completion (ACTUAL): February 1, 2014
• Study Completion (ACTUAL): March 1, 2014

Study Registration Dates

• First Submitted: December 21, 2011
• First Submitted That Met QC Criteria: December 28, 2011
• First Posted (ESTIMATE): December 30, 2011

Study Record Updates

• Last Update Posted (ESTIMATE): November 23, 2016
• Last Update Submitted That Met QC Criteria: October 1, 2016
• Last Verified: October 1, 2016

More Information

Terms related to this study

• Keywords: Cardiac surgery; Mechanical ventilation; Open lung approach; Pulmonary complications; Blood gases
• Additional Relevant MeSH Terms: Cardiovascular Diseases; Respiratory Tract Diseases; Lung Diseases; Thoracic Injuries; Heart Diseases; Wounds and Injuries; Acute Lung Injury; Lung Injury; Ventilator-Induced Lung Injury
• Other Study ID Numbers: InCor-OLA

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO