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NCT Number: NCT06248320

Sigh Ventilation on Postoperative Hypoxemia in Cardiac Surgery

Postoperative pulmonary complications (PPCs) remain a frequent event after pump-on cardiac surgery and are mostly characterized by postoperative hypoxemia.These complications are significant contributors to prolonged intensive care unit admissions and an escalation in in-hospital mortality rates.

The dual impact of general anesthesia with invasive mechanical ventilation results in ventilator-induced lung injury, while cardiac surgery introduces additional pulmonary insults. These include systemic inflammatory responses initiated by cardiopulmonary bypass and ischemic lung damage consequent to aortic cross-clamping. Contributing factors such as blood transfusions and postoperative pain further exacerbate the incidence of PPCs by increasing the permeability of the alveolar-capillary barrier and disrupting mucociliary functions, often culminating in pulmonary atelectasis.

Protective ventilation strategies, inspired by acute respiratory distress syndrome (ARDS) management protocols, involve the utilization of low tidal volumes (6-8mL/kg predicted body weight). However, the uniform application of low tidal volumes, especially when combined with the multifactorial pulmonary insults inherent to cardiac surgery, can precipitate surfactant dysfunction and induce atelectasis.

The role of pulmonary surfactant in maintaining alveolar stability is critical, necessitating continuous synthesis to sustain low surface tension and prevent alveolar collapse. The most potent stimulus for surfactant secretion is identified as the mechanical stretch of type II pneumocytes, typically induced by larger tidal volumes.

This background sets the foundation for a research study aimed at assessing the safety and efficacy of incorporating sighs into perioperative protective ventilation. This approach is hypothesized to mitigate postoperative hypoxemia and reduce the incidence of PPCs in patients undergoing scheduled on-pump cardiac surgery.

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Key information

Conditions

Hypoxemia Acute Lung Injury Cardiac Disease Cardiovascular Diseases Heart Diseases Hypoxia Lung Diseases Lung Injury Pathologic Processes Pathological Conditions, Signs and Symptoms Postoperative Complications Respiratory Tract Diseases Signs and Symptoms Signs and Symptoms, Respiratory

Age range

18 year–80 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Zhongda Hospital, Southeast University

Nanjing, Jiangsu, 210009, China

About this study

The purpose of this single center, parallel group, randomized controlled study is to evaluate the effect of a perioperative sigh ventilation strategy on postoperative outcomes during the first 7 days following cardiac surgery. The study will include 192 adult patients undergoing scheduled on-pump cardiac surgery. The sigh ventilation approach will combine sigh ventilation and lung protective ventilation (6-8 ml/kg/pbw) from intubation to extubation. It will be compared to a conventional approach without sigh ventilation, with lung protective ventilation and positive end-expiratory pressure (PEEP) setting same as the intervention arm. The primary endpoint is the Spo2/Fio2 ratio during the initial post extubation hour. The secondary endpoints are postoperative pulmonary complications and hospital length of stay .

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Elective cardiac surgery with general anesthesia
  • Conventional cardiopulmonary bypass and aortic cross clamp
  • Providing written informed consent by the patient himself/herself or the next of kin

Exclusion criteria

  • Emergent surgery including aortic dissection, cardiac rupture and active endocarditis surgery
  • Left ventricular assist device implantation
  • Patients anticipated to require intraoperative support with Extracorporeal Membrane Oxygenation (ECMO) or Intra-Aortic Balloon Pump (IABP)
  • Chronic pulmonary disease requiring long-term home oxygen therapy
  • Receiving invasive mechanical ventilation within 7 days prior to surgery
  • Preoperative shock
  • Obstructive Sleep Apnea Syndrome (OSAS) requiring intermittent non-invasive ventilatort support
  • Preoperative left ventricular ejection fraction<40%
  • Pulmonary arterial systolic pressure>50 mmHg
  • Redo surgery

Treatment and study plan

Sigh ventilation

Procedure

Sigh breaths were delivered from intubation to extubation. Intervention primarily conducted in the following three stages: 1. From intubation to surgical opening of the chest cavity; 2. From the surgical closure of the chest cavity close and continue unit the operating room exiting; 3. From Intensive Care Unit (ICU) arrival to Spontaneous breathing trial (SBT) start.

Primary outcomes

  1. Time-weighted average pulse oximetry (SpO2/FiO2)

    Time frame: 1 hour after endotracheal extubation

    Calculated the SpO2/FiO2 ratio every 15min during the initial postextubation hour, then averaged the SpO2/FiO2 ratios weighted by measurement interval. The comparison between arms was made through T-test.

Secondary outcomes

  1. Proportion of respiratory failure

    Time frame: first 7 days postextubation

    Mild respiratory failure: SpO2 < 90% or PaO2 < 60 mmHg after breathing ambient air for 10 min (excluding hypoventilation) and corrected with an oxygen supply of 1-3 L/min with a nasal cannula; Moderate respiratory failure: SpO2 < 90% or PaO2 < 60 mmHg despite a 3 L/min oxygen supply with a nasal cannula (excluding hypoventilation) and corrected with an oxygen supply from 4 to 10 L/ min with a face mask; Severe respiratory failure: SpO2 < 90% or PaO2 < 60 mmHg despite a 10 L/min oxygen supply with a face mask (excluding hypoventilation) and corrected with an oxygen supply > 10 L/min with a high-flow face mask or with non-invasive ventilation or with high-flow nasal oxygen therapy or with invasive mechanical ventilation. Using the worst score in the first 7 days postextubation for main analysis.

    Tested between arms through ordinal logistic regression.

  2. Severity of postoperative pulmonary complications

    Time frame: first 7 days after surgery

    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. Using the worst score in the first 7 days after surgery for main analysis.

    Tested between arms through ordinal logistic regression.

  3. Invasive mechanical ventilation (IMV) days

    Time frame: first 7 days after surgery

    Durations of invasive mechanical ventilation.

  4. Reintubation rate

    Time frame: first 7 days after surgery

    Occurrence of endotracheal reintubation.

  5. Proportion of receiving non-invasive ventilation (NIV) or High-flow nasal cannula (HFNC) support

    Time frame: first 7 days after surgery

    Tested through the Fisher exact test or chi-square test.

  6. No ventilatory-support days

    Time frame: first 7 days after surgery

    Days alive and not receive IMV, HFNC and non-invasive ventilatory support.

  7. In-hospital mortality

    Time frame: From the day of surgery up to Hospital discharge or death, maximum censoring at day 28 after surgery

    Deaths occurred during hospital stay

  8. Length of ICU stay

    Time frame: From the day of surgery up to ICU discharge, maximum censoring at day 28 after surgery

    Days since surgery until ICU discharge

  9. Length of hospital stay

    Time frame: From the day of surgery up to Hospital discharge, maximum censoring at day 28 after surgery

    Days since surgery until Hospital discharge

Sponsors and collaborators

Lead sponsor

Zhongda Hospital

Other

Registry information

Official study title

Effect of Perioperative Sigh Ventilation on Postoperative Hypoxemia and Pulmonary Complications After On-pump Cardiac Surgery: A Randomized Controlled Trial

Important dates

Study start
2024
Primary completion
2024
Study completion
2024
First posted
Feb 8, 2024
Registry last updated
Nov 4, 2024

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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