Effect of inspiratory synchronization during pressure-controlled ventilation on lung distension and inspiratory effort

Nuttapol Rittayamai; François Beloncle; Ewan C Goligher; Lu Chen; Jordi Mancebo; Jean-Christophe M Richard; Laurent Brochard

doi:10.1186/s13613-017-0324-z

Effect of inspiratory synchronization during pressure-controlled ventilation on lung distension and inspiratory effort

Ann Intensive Care. 2017 Oct 6;7(1):100. doi: 10.1186/s13613-017-0324-z.

Authors

Nuttapol Rittayamai^{1

2

3}, François Beloncle^{1

2

4}, Ewan C Goligher^{1

5

6

7}, Lu Chen^{1

2}, Jordi Mancebo^{8

9}, Jean-Christophe M Richard^{10

11}, Laurent Brochard^{12

13}

Affiliations

¹ Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, ON, Canada.
² Keenan Research Centre and Li Ka Shing Knowledge Institute, St. Michael's Hospital, 30 Bond St, Toronto, ON, M5B 1W8, Canada.
³ Division of Respiratory Diseases and Tuberculosis, Department of Medicine, Faculty of Medicine Siriraj Hospital, Bangkok, Thailand.
⁴ Medical Intensive Care Unit, Hospital of Angers, University of Angers, Angers, France.
⁵ Department of Medicine, University of Toronto, Toronto, Canada.
⁶ Department of Physiology, University of Toronto, Toronto, Canada.
⁷ Division of Respirology, Department of Medicine, University Health Network and Mount Sinai Hospital, Toronto, Canada.
⁸ Centre de recherche du Centre Hospitalier de l, Université de Montréal (CRCHUM), University of Montreal', Montreal, Canada.
⁹ Servei de Medicina Intensiva, Hospital Sant Pau, Barcelona, Spain.
¹⁰ Emergency Department, General Hospital of Annecy, Annecy, France.
¹¹ INSERM UMR 955 eq 13, Créteil, France.
¹² Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, ON, Canada. BrochardL@smh.ca.
¹³ Keenan Research Centre and Li Ka Shing Knowledge Institute, St. Michael's Hospital, 30 Bond St, Toronto, ON, M5B 1W8, Canada. BrochardL@smh.ca.

Abstract

Background: In pressure-controlled (PC) ventilation, tidal volume (V _T) and transpulmonary pressure (P _L ) result from the addition of ventilator pressure and the patient's inspiratory effort. PC modes can be classified into fully, partially, and non-synchronized modes, and the degree of synchronization may result in different V _T and P _L despite identical ventilator settings. This study assessed the effects of three PC modes on V _T, P _L , inspiratory effort (esophageal pressure-time product, PTP_es), and airway occlusion pressure, P _0.1. We also assessed whether P _0.1 can be used for evaluating patient effort.

Methods: Prospective, randomized, crossover physiologic study performed in 14 spontaneously breathing mechanically ventilated patients recovering from acute respiratory failure (1 subsequently withdrew). PC modes were fully (PC-CMV), partially (PC-SIMV), and non-synchronized (PC-IMV using airway pressure release ventilation) and were applied randomly; driving pressure, inspiratory time, and set respiratory rate being similar for all modes. Airway, esophageal pressure, P _0.1, airflow, gas exchange, and hemodynamics were recorded.

Results: V _T was significantly lower during PC-IMV as compared with PC-SIMV and PC-CMV (387 ± 105 vs 458 ± 134 vs 482 ± 108 mL, respectively; p < 0.05). Maximal P _L was also significantly lower (13.3 ± 4.9 vs 15.3 ± 5.7 vs 15.5 ± 5.2 cmH₂O, respectively; p < 0.05), but PTP_es was significantly higher in PC-IMV (215.6 ± 154.3 vs 150.0 ± 102.4 vs 130.9 ± 101.8 cmH₂O × s × min^-1, respectively; p < 0.05), with no differences in gas exchange and hemodynamic variables. PTP_es increased by more than 15% in 10 patients and by more than 50% in 5 patients. An increased P _0.1 could identify high levels of PTP_es.

Conclusions: Non-synchronized PC mode lowers V _T and P _L in comparison with more synchronized modes in spontaneously breathing patients but can increase patient effort and may need specific adjustments. Clinical Trial Registration Clinicaltrial.gov # NCT02071277.

Keywords: Airway pressure release ventilation; Lung-protective ventilation; Spontaneous ventilation; Transpulmonary pressure; Ventilator-induced lung injury.

Associated data

ClinicalTrials.gov/NCT02071277