Sigh Breaths for Trauma Patients Receiving Mechanical Ventilation

Abstract

Occasionally, newspapers report positive stories of animal species believed to be extinct, only to be discovered alive and repopulating their habitats. 1 In this issue of JAMA, Albert and colleagues 2 assessed the role of sigh breaths in ventilated trauma patients at risk of acute respiratory distress syndrome. Though sighs did not result in a significant improvement in the primary outcome, they were well-tolerated and were associated with an improvement in some clinical outcomes. The sigh, believed to be extinct, is back. In 1976, Fairley 3 declared that, "The mechanical ventilation sigh is a Dodo" (the dodo is an extinct flightless bird). Despite this statement, sighs survived in the clinical practice of several centers and were the subject of substantial clinical research. [4][5][6] Importantly, they also remained a viable option in various commercial ventilators.In respiratory physiology, the term sigh refers to a deep breath, often exhaled in sorrow, normally a complement to spontaneous breathing patterns, that is taken once every few minutes to maintain lung volume and avoid atelectasis. 7 The sigh, in other words, keeps alveoli open that might otherwise close or reopens alveoli that had collapsed. As such, the sigh breath is sometimes considered a recruitment maneuver, albeit not falling under the prolonged high-pressure type. 8 The physiologic importance of the sigh was brought to the attention of anesthesiologists in the early 1960s, as a necessary maneuver to maintain oxygenation and lung compliance during mechanical ventilation in patients undergoing anesthesia. 9 In the following years, prolonged mechanical ventilation was established as a lifesaving procedure in acute respiratory failure. Soon, physicians were led to use high tidal volumes (10-15 mL/kg actual body weight), once again to preserve lung volume, compliance, and oxygenation. It is likely that the use of high tidal volumes, coupled with the widespread use of positive end-expiratory pressure (PEEP), consigned sighs to the background-the large volumes and high positive pressure splinted the lung open, without need for additional recruitment via sigh breaths. In Fairley's editorial, 3 he recommended, "In patients with normal lungs, each tidal volume should be large. In those with acute pulmonary failure, PEEP (to maximum compliance) should be used. Sighs, superimposed upon this, are likely to damage the lungs. The sigh is dead."In the following 2 decades, the concept of ventilatorinduced lung injury was developed in diverse experimental and clinical settings; tidal volumes were lowered, and eventually the National Institutes of Health-sponsored ARMA trial demonstrated that using a tidal volume of 12 mL/kg ideal body weight instead of 6 mL/kg was associated with a substantial Related articleOpinion EDITORIAL

Sigh Breaths in Patients With Trauma Receiving Mechanical Ventilation

“…In an Editorial that accompanied the article, Bellani and Pesenti speculated that the fraction of inspired oxygen (F io 2 ) or positive end-expiratory pressure (PEEP) might have been managed differently in the 2 study groups (ie, lower PEEP and F io 2 in the sigh group), contributing to a better outcome.…”