Quantifying unintended exposure to high tidal volumes from breath stacking dyssynchrony in ARDS: the BREATHE criteria

Abstract

Purpose Breath stacking dyssynchrony generates higher tidal volumes than intended, potentially increasing lung injury risk in acute respiratory distress syndrome (ARDS). Lack of validated criteria to quantify breath stacking dyssynchrony contributes to its under-recognition. This study evaluates performance of novel, objective criteria for quantifying breath stacking dyssynchrony (BREATHE Criteria) compared to existing definitions and tests if neuromuscular blockade eliminates high-volume breath stacking dyssynchrony in ARDS. Methods Airway flow and pressure were recorded continuously for up to 72 hours in 33 patients with ARDS receiving volume-preset assist-control ventilation. The flow-time waveform was integrated to calculate tidal volume breath-by-breath. The BREATHE Criteria considered five domains in evaluating for breath stacking dyssynchrony: ventilator cycling, interval expiratory volume, cumulative inspiratory volume, expiratory time, and inspiratory time. Results The observed tidal volume of BREATHE stacked breaths was 11.3 [9.7—13.3] mL/kg predicted body weight, significantly higher than the preset volume (6.3 [6.0—6.8] mL/kg; p<.001). BREATHE identified more high-volume breaths (≥2 mL/kg above intended volume) than the other existing objective criteria for breath stacking (27 [7—59] vs 19 [5—46] breaths/hour; p<.001). Agreement between BREATHE and visual waveform inspection was high (raw agreement 96.4–98.1%; phi 0.80–0.92). Breath stacking dyssynchrony was near-completely eliminated during neuromuscular blockade (0 [0—1] breaths/hour; p<.001). Conclusions The BREATHE Criteria provide an objective definition of breath stacking dyssynchrony emphasizing occult exposure to high tidal volumes. BREATHE identified high-volume breaths missed by other methods for quantifying this dyssynchrony. Neuromuscular blockade prevented breath stacking dyssynchrony, assuring provision of the intended lung-protective strategy.

Ventilation-induced lung injury exists in spontaneously breathing patients with acute respiratory failure: Yes

“…Although we do not know the precise mechanisms, this strongly suggested a deleterious effect of spontaneous breathing under mechanical ventilation. Spontaneous breathing could increase ventilation by breath stacking [11] or reverse triggering [12], but Yoshida et al also showed that, without increasing tidal volume, spontaneous ventilation with a high respiratory drive could induce an internal redistribution of the inspired tidal volume generating local injurious forces [13]. Recently, we proposed the concept of patient self-inflicted lung injury (P-SILI) to describe all these conditions where a high respiratory drive induced by local lung injury could result in global or regional pressure changes susceptible to aggravating the initial lung injury [14].…”

Esophageal pressure: research or clinical tool?

“…There is also increasing concern that dyssynchrony may cause large transpulmonary pressure swings and inappropriately large tidal volumes that may be especially harmful in critically ill patients that are receiving lungprotective ventilation [33]. While some dyssynchrony is obvious while measuring PAO alone, the type and severity of an event is often missed or underestimated if not measuring PL (.…”

“…Double triggering and reverse triggering are commonly observed phenomenon that can be distinguished by using esophageal manometry to measure swings in PEs [33]. Double triggering occurs when a patient has a respiratory drive/effort greater than the support delivered on the ventilator.…”

Detection of patient-ventilator asynchrony should be improved: and then what?

“…Breath stacking occurred in about three fourth of hours during the observation time, presuming no use of neuromuscular blockade (NMB). With NMB use, breath stacking asynchrony was eliminated (9).…”

“…In the study by Beitler et al, the use of NMB was shown to abolish breath stacking asynchrony effectively (9). The somewhat outdated concept of NMB use in patients with early ARDS was rediscovered by recent data showing improved 90 days in-hospital survival during timecycled, volume preset AC with constant inspiratory flow (12).…”