Newly Published
Critical Care Medicine  |   July 2018
Standardized Unloading of Respiratory Muscles during Neurally Adjusted Ventilatory Assist: A Randomized Crossover Pilot Study
Author Notes
  • From the Perioperative Medicine and Intensive Care Medicine, Karolinska University Hospital, Solna, Sweden (F.C.J., P.V.S., D.N.); Department of Physiology and Pharmacology (F.C.J., M.K.E.B.W., P.J.R., D.N., P.V.S.) and Department of Women’s and Children’s Health (S.E.), Karolinska Institutet, Stockholm, Sweden; Maquet Critical Care, Solna, Sweden (F.J., M.K.E.B.W.); Department of Surgical Sciences, Uppsala University, Uppsala, Sweden (F.S.-S.); Department of Intensive Care Medicine, Hospital Universitario y Politecnico, La Fe, Valencia, Spain (F.S.-S.); and CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain (F.S.-S.).
  • Supplemental Digital Content is available for this article. Direct URL citations appear in the printed text and are available in both the HTML and PDF versions of this article. Links to the digital files are provided in the HTML text of this article on the Journal’s Web site (www.anesthesiology.org).
    Supplemental Digital Content is available for this article. Direct URL citations appear in the printed text and are available in both the HTML and PDF versions of this article. Links to the digital files are provided in the HTML text of this article on the Journal’s Web site (www.anesthesiology.org).×
  • The work has been presented in a preliminary draft at the Ph.D. dissertation session on June 10, 2016, in Stockholm, Sweden.
    The work has been presented in a preliminary draft at the Ph.D. dissertation session on June 10, 2016, in Stockholm, Sweden.×
  • Submitted for publication October 13, 2017. Accepted for publication May 29, 2018.
    Submitted for publication October 13, 2017. Accepted for publication May 29, 2018.×
  • Acknowledgments: The authors thank the nursing staff of the neurointensive care unit and Jonas Blixt, M.D., Karolinska University Hospital (Stockholm, Sweden), for their assistance.
    Acknowledgments: The authors thank the nursing staff of the neurointensive care unit and Jonas Blixt, M.D., Karolinska University Hospital (Stockholm, Sweden), for their assistance.×
  • Research Support: Supported by the regional agreement on medical and clinical research (ALF) between the Stockholm Country Council and the Karolinska Institutet (Stockholm, Sweden) and by a research grant from Maquet Critical Care (Solna, Sweden). Maquet Critical Care provided for the material costs related to the study (electrical activity of the diaphragm catheters and electrical impedance tomography belts).
    Research Support: Supported by the regional agreement on medical and clinical research (ALF) between the Stockholm Country Council and the Karolinska Institutet (Stockholm, Sweden) and by a research grant from Maquet Critical Care (Solna, Sweden). Maquet Critical Care provided for the material costs related to the study (electrical activity of the diaphragm catheters and electrical impedance tomography belts).×
  • Competing Interests: Dr. Campoccia Jalde received a research grant from Maquet Critical Care (Solna, Sweden) at the time of the study. Dr. Mats Wallin and M.Sc. Fredrik Jalde are currently working at Maquet Critical Care.
    Competing Interests: Dr. Campoccia Jalde received a research grant from Maquet Critical Care (Solna, Sweden) at the time of the study. Dr. Mats Wallin and M.Sc. Fredrik Jalde are currently working at Maquet Critical Care.×
  • Reproducible Science: Full protocol available at: francesca.campoccia-jalde@sll.se. Raw data available at: francesca.campoccia-jalde@sll.se.
    Reproducible Science: Full protocol available at: francesca.campoccia-jalde@sll.se. Raw data available at: francesca.campoccia-jalde@sll.se.×
  • Correspondence: Address correspondence to Dr. Jalde: Karolinska University Hospital, Karolinska Vägen, 171 76 Stockholm, Sweden. francesca.campoccia-jalde@sll.se. Information on purchasing reprints may be found at www.anesthesiology.org or on the masthead page at the beginning of this issue. Anesthesiology’s articles are made freely accessible to all readers, for personal use only, 6 months from the cover date of the issue.
Article Information
Critical Care Medicine / Critical Care / Respiratory System
Critical Care Medicine   |   July 2018
Standardized Unloading of Respiratory Muscles during Neurally Adjusted Ventilatory Assist: A Randomized Crossover Pilot Study
Anesthesiology Newly Published on July 24, 2018. doi:10.1097/ALN.0000000000002335
Anesthesiology Newly Published on July 24, 2018. doi:10.1097/ALN.0000000000002335
Abstract

What We Already Know about This Topic:

  • Neurally adjusted ventilatory assist matches the mechanical pressure from the ventilator to the patient’s respiratory drive sensed from the electrical activity of the diaphragm, but the optimal degree of diaphragm unloading is uncertain

What This Article Tells Us That Is New:

  • This pilot study of 10 patients titrated neurally adjusted ventilatory assist to different levels of diaphragm unloading; less unloading was associated with greater diaphragm activity and improved ventilation of dependent lung

Background: Currently, there is no standardized method to set the support level in neurally adjusted ventilatory assist (NAVA). The primary aim was to explore the feasibility of titrating NAVA to specific diaphragm unloading targets, based on the neuroventilatory efficiency (NVE) index. The secondary outcome was to investigate the effect of reduced diaphragm unloading on distribution of lung ventilation.

Methods: This is a randomized crossover study between pressure support and NAVA at different diaphragm unloading at a single neurointensive care unit. Ten adult patients who had started weaning from mechanical ventilation completed the study. Two unloading targets were used: 40 and 60%. The NVE index was used to guide the titration of the assist in NAVA. Electrical impedance tomography data, blood-gas samples, and ventilatory parameters were collected.

Results: The median unloading was 43% (interquartile range 32, 60) for 40% unloading target and 60% (interquartile range 47, 69) for 60% unloading target. NAVA with 40% unloading led to more dorsal ventilation (center of ventilation at 55% [51, 56]) compared with pressure support (52% [49, 56]; P = 0.019). No differences were found in oxygenation, CO2, and respiratory parameters. The electrical activity of the diaphragm was higher during NAVA with 40% unloading than in pressure support.

Conclusions: In this pilot study, NAVA could be titrated to different diaphragm unloading levels based on the NVE index. Less unloading was associated with greater diaphragm activity and improved ventilation of the dependent lung regions.