Continuing ventilation during cardiopulmonary bypass reduced pulmonary complications

Design

Systematic review and meta-analysis of RCTs

Population

Adults undergoing cardiac surgery with cardiopulmonary bypass (39 pooled trials)

Primary outcome

All-cause mortality; pulmonary complications secondary

Effect

Ventilation on bypass: pulmonary complications RR 0.87 (0.79 to 0.96)

This meta-analysis identified 105 randomised trials of ventilation strategies in adult cardiac surgery with bypass, of which 39 could be pooled. Continuing ventilation during bypass, rather than leaving the lungs deflated, reduced postoperative pulmonary complications (RR 0.87, 95% CI 0.79 to 0.96; I² = 0%, 15 trials).

Postoperative non-invasive respiratory support was associated with lower mortality (4.1% vs 6.4%; RR 0.60, 0.34 to 1.08), but the interval crosses 1 and only five trials contributed. Pressure versus volume control during surgery and adaptive support ventilation after it made no difference.

The bypass finding is consistent and low-cost to adopt, though protocols varied widely between trials.

• Consider low tidal volume ventilation during bypass rather than a fully deflated lung
• Plan postoperative non-invasive support for patients at high pulmonary risk
• Mode of ventilation — pressure or volume control — did not matter
• Agree a unit protocol with perfusionists and surgeons, as trial protocols varied

Why it matters

It gives randomised support to a practice many units have treated as optional.

Don't overread it

The mortality signal with non-invasive support is not statistically significant and is hypothesis-generating only.

The statistics, in plain English

A risk ratio of 0.87 with no heterogeneity means about 13% fewer pulmonary complications, consistently across trials. The mortality interval (0.34 to 1.08) includes no effect.

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