Ultrasound Assessment of Respiratory Workload With High-Flow Nasal Oxygen Versus Other Noninvasive Methods After Chest Surgery

J Cardiothorac Vasc Anesth. 2019 Nov;33(11):3042-3047. doi: 10.1053/j.jvca.2019.05.020. Epub 2019 May 21.

Abstract

Objective: To compare the respiratory workload using the diaphragm thickening fraction (DTf) determined by sonography during high-flow nasal oxygen (HFNO), standard oxygen therapy (SOT), and noninvasive bilevel positive airway pressure support (BIPAP) in patients with acute respiratory failure (ARF) after cardiothoracic surgery.

Design: Prospective controlled clinical trial.

Setting: A French 23-bed cardiothoracic surgical intensive care unit.

Participants: Nonintubated patients with ARF after cardiothoracic surgery or while awaiting lung transplantation.

Interventions: HFNO (50 L/min), SOT via a standard facemask, and BIPAP (pressure support, 4 cmH2O; positive end-expiratory pressure [PEEP], 4 cmH2O), with FIO2 kept constant were successively applied and compared. With BIPAP, pressure support or PEEP increments up to 8 cmH2O were compared with baseline settings. Each measurement was made after stable breathing for 5 minutes.

Measurements and main results: Fifty patients aged 60.0 ± 12.2 years were enrolled, including 14 (28%) with obesity. Mean PaO2/FIO2 was 153 ± 55 mmHg. DTf was lower with HFNO and BIPAP than with SOT (respectively 21.2% ± 15.1% v 30.9% ± 21.1% and 17.8% ± 19.1% v 30.9% ± 21.1%, p < 0.001) and was not different with HFNO versus BIPAP (p = 0.22). With BIPAP, increasing pressure support to 8 cmH2O decreased DTf (21.0% ± 14.3% v 28.8% ± 19.8%, p = 0.009), whereas increasing PEEP to 8 cmH2O did not (25.2% ± 17.2% v 28.8% ± 19.8%, p = 0.79). Tidal volume increased to 10.6 ± 3.4 mL/kg with 8 cmH2O pressure support v 8.8 ± 2.7 mL/kg with 4 cmH2O pressure support (p < 0.001).

Conclusion: HFNO provides a comparable respiratory workload decrease compared with BIPAP at lower levels of pressure support and PEEP compared with SOT. Increasing BIPAP pressure support may provide higher levels of assistance but carries a risk of overdistension.

Keywords: acute lung injury; cardiac surgery; diaphragm sonography; high flow nasal oxygen; noninvasive ventilation.

Publication types

  • Controlled Clinical Trial

MeSH terms

  • Diaphragm / diagnostic imaging*
  • Diaphragm / physiopathology
  • Female
  • Follow-Up Studies
  • Humans
  • Male
  • Middle Aged
  • Nose
  • Oxygen / metabolism*
  • Oxygen Inhalation Therapy / methods
  • Positive-Pressure Respiration / methods*
  • Postoperative Period
  • Prospective Studies
  • Respiratory Distress Syndrome / metabolism
  • Respiratory Distress Syndrome / physiopathology
  • Respiratory Distress Syndrome / therapy*
  • Respiratory Mechanics / physiology*
  • Thoracic Surgical Procedures / methods*
  • Tidal Volume
  • Ultrasonography / methods*

Substances

  • Oxygen