Intensive Alveolar Recruitment Protocol After Cardiac Surgery

Cardiac Disease Clinical Trial

Official title:

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

Clinical Trial Details — Status: Recruiting

Administrative data

• NCT number: NCT01502332
• Other study ID #: InCor-OLA
• Status: Recruiting
• Phase: N/A
• First received: December 21, 2011
• Last updated: December 28, 2011
• Start date: December 2011
• Est. completion date: December 2013

Study information

• Verified date: December 2011
• Source: University of Sao Paulo
• Contact: n/a
• Is FDA regulated: No
• Health authority: Brazil: Ethics Committee
• Study type: Interventional

Clinical Trial Summary

The purpose of this study is 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 will select patients presenting signals of deficient gas exchange (PaO2/FIO2 < 250 at a PEEP 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, will be 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 will follow the routine weaning protocol and physiotherapy protocol of the institution.

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 will compare 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, will be compared to the standard alveolar recruitment protocol of the institution, where an opening pressure of 30 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 will follow the routine weaning protocol and physiotherapy protocol of the institution.

Our hypothesis is 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 will test if the effect of an aggressive alveolar recruitment protocol will be translated in a better lung compliance, better gas exchange, and fewer pulmonary complications in the post-operative periods (this latter is going to be our primary outcome). Analysis of the length of stay will be also scrutinized, consisting in our secondary outcome. All hemodynamic complications will be reported, since we can also anticipate that events of hemodynamic impairment may be more frequent in the aggressive recruitment arm, eventually obscuring the expected benefits .

Recruitment information / eligibility

• Status: Recruiting
• Enrollment: 320
• Est. completion date: December 2013
• Est. primary completion date: December 2012
• Accepts healthy volunteers: No
• Gender: Both
• Age group: 18 Years to 80 Years

Eligibility

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 < 60mmHg

• 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 Design

Allocation: Randomized, Endpoint Classification: Efficacy Study, Intervention Model: Parallel Assignment, Masking: Open Label, Primary Purpose: Treatment

Related Conditions & MeSH terms

• Acute Lung Injury
• Cardiac Disease
• Heart Diseases
• Lung Injury
• Respiratory Distress Syndrome, Adult
• Ventilator Induced Lung Injury
• Ventilator-Induced Lung Injury

Intervention

Other:
• Mechanical ventilation strategy
Intensive Alveolar Recruitment ARM: 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 VT = 6 mL/kg/pbw.
• Mechanical ventilation strategy
Moderate alveolar recruitment ARM: 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.

Locations

Country	Name	City	State
Brazil	Instituto do Coração (Incor) - University of São Paulo	São Paulo

Sponsors (2)

Lead Sponsor	Collaborator
University of Sao Paulo	InCor Heart Institute

Country where clinical trial is conducted

Brazil, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	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, and degree (4) means the need of mechanical ventilation for more than 48 hours after surgery or after reintubation.; The comparison will use this ordinal variable, representing the highest score achieved during the post-operative period. The comparison between arms will be made through the Mann-Whitney U test.	Participants will be followed for the duration of hospital stay, an expected average stay of 12 days after surgery	No
Secondary	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 will be performed at 28 days. Patients dying before leaving the ICU will be censored as not discharged from ICU at day 28.	From the day of surgery up to ICU discharge, an expected average of 6 days, and maximum censoring at day 28 after surgery	No
Secondary	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 will be performed at 28 days. Patients dying before leaving the Hospital will be censored as not discharged from Hospital at day 28.	From the day of surgery up to Hospital discharge, an expected average of 12 days, and maximum censoring at day 28 after surgery	No
Secondary	Incidence of barotrauma	Confirmed by X-ray. Test with logistic regression	Five days after surgery	No
Secondary	Hospital mortality	Deaths occurred during hospital stay, tested with logistic regression.	From the day of surgery up to Hospital discharge or death, an expected average of 12 days, with no maximum censoring.	No