Your patient is a 63-year-old smoker with COPD.
He’d been in fairly good health until a few months ago, when his doctors found a suspicious mass on a screening colonoscopy. Now, surgery is planned to resect part of his colon. He’s anxious, not just about his cancer diagnosis, but also about how his lungs will tolerate the intubation required for the procedure.
Is there anything we can do, he asks you, to decrease his risk of pulmonary complications?
Since the landmark ARDSnet trial of low tidal volume ventilation was published in NEJM in 2000, we have known that setting a ventilator to deliver lower volumes of air with higher levels of pressure protects injured lungs and saves lives.
However, this finding left doctors to wonder whether similar ventilator settings should be used in other populations – specifically patients with lung injuries other than acute respiratory distress syndrome, or those who are at risk for lung injury. In the medical units, these settings have become the norm.
But in the surgical world, the question has remained open. With the thought that maybe higher volume breaths could help the surgical patient from developing lung collapse (atelectasis) and low oxygen levels, high tidal volumes and low pressures remain the standard in many operating rooms.
But a study published in this week’s issue of NEJM, “A Trial of Intraoperative Low-Tidal-Volume Ventilation in Abdominal Surgery,” suggests that this practice might be doing more harm than good.
To answer this question, Dr. Emmanuel Futier and colleagues enrolled 400 patients, all gearing up for abdominal surgery, all with an intermediate to high risk for pulmonary complications. To risk stratify likelihood of pulmonary complications, they used a system that divides patients into five risk classes based on factors including type of surgery, age, COPD, use of cigarettes and alcohol and steroids.
These patients were randomly assigned to one of two ventilator strategies – “non protective ventilation,” with larger volumes and no positive end expiratory pressure (PEEP), or lung-protective ventilation, with smaller volumes and higher PEEP. Those in the low volume group received intermittent “recruitment maneuvers,” in which pressures were transiently turned up to high levels with the goal to open up any collapsed lung.
The results were striking. In the first seven days after surgery, 17 percent of the patients receiving the larger volume ventilation needed noninvasive ventilation or intubation, compared to only 5 percent in the low-tidal-volume group – overall, a 69 percent reduction in the number of patients requiring ventilator support within the first week after surgery.
The benefits didn’t end there. Those in the lung protective group were also less likely to suffer from the composite outcome of sepsis, severe sepsis, shock or death. And while there was no significant mortality difference between groups, those in the lung protective group were more likely to leave the hospital earlier.
The authors conclude, “Our study provides evidence that a multifaceted strategy of prophylactic lung-protective ventilation during surgery, as compared with a practice of non protective mechanical ventilation, results in fewer postoperative complications and reduced health care utilization.”
The answer to your patient? Yes. Whether in the operating room or a medical intensive care unit, lung-protective ventilation – as the name suggests – is the way to go.