Background

Data on assessment and management of dyspnea in patients on venoarterial extracorporeal membrane oxygenation (ECMO) for cardiogenic shock are lacking. The hypothesis was that increasing sweep gas flow through the venoarterial extracorporeal membrane oxygenator may decrease dyspnea in nonintubated venoarterial ECMO patients exhibiting clinically significant dyspnea, with a parallel reduction in respiratory drive.

Methods

Nonintubated, spontaneously breathing, supine patients on venoarterial ECMO for cardiogenic shock who presented with a dyspnea visual analog scale (VAS) score of greater than or equal to 40/100 mm were included. Sweep gas flow was increased up to +6 l/min by three steps of +2 l/min each. Dyspnea was assessed with the dyspnea-VAS and the Multidimensional Dyspnea Profile. The respiratory drive was assessed by the electromyographic activity of the alae nasi and parasternal muscles.

Results

A total of 21 patients were included in the study. Upon inclusion, median dyspnea-VAS was 50 (interquartile range, 45 to 60) mm, and sweep gas flow was 1.0 l/min (0.5 to 2.0). An increase in sweep gas flow significantly decreased dyspnea-VAS (50 [45 to 60] at baseline vs. 20 [10 to 30] at 6 l/min; P < 0.001). The decrease in dyspnea was greater for the sensory component of dyspnea (−50% [−43 to −75]) than for the affective and emotional components (−17% [−0 to −25] and −12% [−0 to −17]; P < 0.001). An increase in sweep gas flow significantly decreased electromyographic activity of the alae nasi and parasternal muscles (−23% [−36 to −10] and −20 [−41 to −0]; P < 0.001). There was a significant correlation between the sweep gas flow and the dyspnea-VAS (r = −0.91; 95% CI, −0.94 to −0.87), between the respiratory drive and the sensory component of dyspnea (r = 0.29; 95% CI, 0.13 to 0.44) between the respiratory drive and the affective component of dyspnea (r = 0.29; 95% CI, 0.02 to 0.54) and between the sweep gas flow and the alae nasi and parasternal (r = −0.31; 95% CI, −0.44 to −0.22; and r = −0.25; 95% CI, −0.44 to −0.16).

Conclusions

In critically ill patients with venoarterial ECMO, an increase in sweep gas flow through the oxygenation membrane decreases dyspnea, possibly mediated by a decrease in respiratory drive.

Editor’s Perspective
What We Already Know about This Topic
  • Dyspnea is a common presenting symptom in critically ill patients and is associated with considerable suffering both long and short term

  • Efforts to more objectively quantify the physical and emotional components associated with it have been a focus on research

  • With the increasing use of extracorporeal oxygenation and cardiac support strategies, treatment of dyspnea may be alleviated but not completely controlled

What This Article Tells Us That Is New
  • The authors evaluated the impact of changing the sweep speed of the membrane oxygenator in spontaneously breathing, nonintubated patients with cardiogenic shock, carefully assessing multiple sensory, physical, and emotional components of dyspnea and respiratory drive

  • Increasing sweep speed up to 6 l/min in 2-l/min steps was associated with a significant decrease in overall dyspnea visual analog scale, greatest in the measured sensory component, and decreased electromyography activity of dyspnea-related musculature

  • These effects appear to be possibly mediated by a decrease in respiratory drive

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