Consider Lower Peak Pulmonary Pressure to Improve Intraop and Postop Outcomes

As you know, postoperative pulmonary complications, or pulmonary injury, is a well-documented group of complications that occur after most major surgeries. With these complications come the following negative outcomes:

1. Increased patient mortality rate by four times
2. Increased hospital and ICU length of stay
3. More than $20,000 in institutional expenses (per event)

Among your cardiac surgery patients, who is at risk? Well, really, everyone — for “measurable derangements in
pulmonary function” occur in nearly all patients who undergo cardiac surgery. So, given that fact, how can you
best plan for intraoperative and postoperative pulmonary complications after cardiac surgery?

3 Components of a Modern Ventilation Bundle

The practice of intraoperative lung-protective ventilation is one very important part in the process of care associated with postop pulmonary complications. Modern ventilation approaches in surgery include a bundle of three separate functions:

• Lower tidal volumes (VT)
• Lower peak pulmonary (or driving) pressures1
• Positive end-expiratory pressure (PEEP)

Each function, or component, contributes independently (as well as collectively) to the reduction of postop pulmonary complications. Today, the exact contribution of each function in reducing complications in your adult cardiac surgical population is not known, and further studies are needed. However, a recent study did reveal some interesting findings regarding the total impact of the modern ventilation bundle — and, specifically, the advantages of administering lower peak pulmonary pressure in the surgical room.

Results of the Study

In a recent observational cohort study of 4,694 cases discussed in Intraoperative Mechanical Ventilation and Postoperative Pulmonary Complications after Cardiac Surgery, the authors reviewed nonemergent cardiac surgical procedures using cardiopulmonary bypass at a tertiary care academic medical center from 2006 to 2017. What were their findings?

Overall, an intraoperative lung-protective ventilation bundle was associated with decreased pulmonary complications.

The three individual components of the ventilation bundle (noted above), via a sensitivity analysis, were also analyzed separately. Here are the results:

Modified driving pressure (below 16 cm H₂O) was associated with decreased pulmonary complications, while lower tidal volumes (below 8 ml/kg) and positive end-expiratory pressure (greater than or equal to 5 cm H₂O) were not associated with decreased pulmonary
complications.

Additionally, another recent study2² (during thoracic surgery) also demonstrated “a driving pressure-guided ventilation strategy during one-lung ventilation to be similarly associated with a lower incidence of postoperative pulmonary complications” (as compared with conventional ventilation strategies).

Conclusion: What This Might Mean for Your Practice

Today, anesthesiologists have the opportunity to provide improved patient care by implementing a lung-protective ventilation protocol favoring lower peak pulmonary pressure. As studies have shown, this can lead to improved patient outcomes. However, due to the observational nature of the study discussed here, these findings will require further evaluation and validation. In the meantime, where appropriate, you can favor lower peak pulmonary pressure in your operating room, and watch for improved intraop and postop outcomes.

1. Please note that this blog does not have time to cover, but acknowledges that there is also a difference between peak pulmonary pressure and mean (average) ventilation pressures that should be taken into consideration.
2. Park M, Ahn HJ, Kim JA,Yang M, Heo BY, Choi JW, Kim YR, Lee SH, Jeong H, Choi SJ, Song IS: Driving pressure during thoracic surgery: A randomized clinical trial. Anesthesiology 2019; 130:385–93.

Read More: