Lung Injury Is Induced by Abrupt Increase in Respiratory Rate but Prevented by Recruitment Maneuver in Mild Acute Respiratory Distress Syndrome in Rats

Abstract

Background Gradually changing respiratory rate (RR) over time to reduce ventilation-induced lung injury (VILI) has not been investigated. We hypothesized that gradual, compared to abrupt, increments in RR would mitigate VILI and that recruitment maneuver (RM) prior to abrupt increasing RR may prevent injurious biological impact. Methods Twenty-four hours after intratracheal administration of Escherichia coli lipopolysaccharide, 49 male Wistar rats were anesthetized and mechanically ventilated (VT=6ml/kg, PEEP=3cmH2O) with RR increase patterns as follows (n=7/group): (1)control-1, RR=70bpm for 2h; (2) and (3)abrupt increases of RR for 1h and 2h, respectively, both for 2h; (4)shorter RR adaptation, gradually increasing RR (from 70 to 130bpm over 30min); (5)longer RR adaptation, more gradual increase in RR (from 70 to 130bpm over 60min), both for 2h; (6)control-2, abrupt increase of RR maintained for 1h; and (7)control-3, RM [CPAP=30cmH2O for 30s] followed by control-2 protocol. Results At the end of 1h of mechanical ventilation, cumulative diffuse alveolar damage scores were lower in shorter (11.0 [8.0–12.0]) and longer (13.0 [11.0–14.0]) RR adaptation groups than in animals with abrupt increase of RR for 1 h (25.0 [22.0–26.0] p=0.035, and p=0.048, respectively) and 2 h (35.0 [32.0–39.0], p=0.003, and p=0.040, respectively); mechanical power and lung heterogeneity were lower, and alveolar integrity was higher, in the longer RR adaptation group compared with abruptly adjusted groups; markers of lung inflammation (IL-6), epithelial (CC-16) and endothelial cell damage (VCAM-1) were higher in both abrupt groups, but not in either RR adaptation group, compared with controls. RM prevented the increase in VCAM-1 and CC-16 gene expressions in the abruptly increased RR groups. Conclusion In mild experimental ARDS in rats, gradually increasing RR, compared with abruptly doing so, can mitigate the development of VILI. In addition, recruitment maneuver prevented the injurious biological impact of abrupt increases in RR.

High positive end-expiratory pressure ventilation mitigates the progression from unilateral pulmonary contusion to ARDS: An animal study

“…Besides the high RR itself contributing to VILI, there seems to be an effect of the time allowed for the transition from low to high RR on the magnitude of VILI. Rapid transitions, as in our OLC group, may increase VILI 26,28,37 . Among the complex interactions between contributors to VILI, there is also an influence of the degree of lung recruitment on the relationship between RR and VILI 26,37 .…”

“…26,28,37 Among the complex interactions between contributors to VILI, there is also an influence of the degree of lung recruitment on the relationship between RR and VILI. 26,37 To, even more, complicate the interpretation of the effects seen in our OLC group, EIT monitoring suggested the contribution of another cause of VILIlung hyperinflation. While this may have remained undetected or underestimated in end-expiratory CT scans, EIT showed a displacement of regional ventilation away from ventral to dorsal lung areas, which may indicate ventral hyperinflation 29,38 (Supplemental Digital Content 2, http://links.lww.…”

Non-Ventilatory Co-Factors of Ventilator-Induced Lung Injury

“…shown experimentally for recruiting maneuvers [55], large tidal volumes [56], increments of PEEP [57] and higher frequency [58].…”

Challenges in ARDS Definition, Management, and Identification of Effective Personalized Therapies

“…There are several other examples in the literature that may deserve further discussion. In conclusion, we need to highlight that slow changes in ventilatory parameters should be preferred over abrupt changes to limit further damage to the lung [ 60 ].…”