Filippo Albani1, Luigi Pisani2,3, Gianni Ciabatti4, Federica Fusina5, Barbara Buizza6, Anna Granato1, Valeria Lippolis7, Eros Aniballi8, Francesco Murgolo9, Antonio Rosano1, Nicola Latronico6,10, Massimo Antonelli11, Salvatore Grasso9, Giuseppe Natalini1. 1. Department of Anesthesia and Intensive Care, Fondazione Poliambulanza, Brescia, Italy. 2. Department of Anesthesia and Intensive Care, Miulli Regional Hospital, Acquaviva Delle Fonti, Bari, Italy. 3. Mahidol Oxford Clinical Research Unit (MORU), Bangkok, Thailand. 4. Department of Anesthesiology, Neurointensive Care Unit, Azienda Ospedaliera Universitaria Careggi, Firenze, Italy. 5. Department of Anesthesia and Intensive Care, Fondazione Poliambulanza, Brescia, Italy. f.fusina@gmail.com. 6. Department of Anesthesia and Intensive Care, Spedali Civili, Brescia, Italy. 7. Department of Anesthesia and Intensive Care, Mater Dei Hospital, Bari, Italy. 8. Department of Anesthesia, I.R.C.C.S. MultiMedica, Sesto San Giovanni, Milano, Italy. 9. Department of Emergency and Organ Transplantation, University of Bari, Bari, Italy. 10. Department of Medical and Surgical Specialties, Radiological Sciences and Public Health, University of Brescia, Brescia, Italy. 11. Department of Intensive Care and Anesthesiology, Fondazione Policlinico, Universitario A. Gemelli, Roma, Italy.
Abstract
BACKGROUND: The evaluation of patient effort is pivotal during pressure support ventilation, but a non-invasive, continuous, quantitative method to assess patient inspiratory effort is still lacking. We hypothesized that the concavity of the inspiratory flow-time waveform could be useful to estimate patient's inspiratory effort. The purpose of this study was to assess whether the shape of the inspiratory flow, as quantified by a numeric indicator, could be associated with inspiratory effort during pressure support ventilation. METHODS: Twenty-four patients in pressure support ventilation were enrolled. A mathematical relationship describing the decay pattern of the inspiratory flow profile was developed. The parameter hypothesized to estimate effort was named Flow Index. Esophageal pressure, airway pressure, airflow, and volume waveforms were recorded at three support levels (maximum, minimum and baseline). The association between Flow Index and reference measures of patient effort (pressure time product and pressure generated by respiratory muscles) was evaluated using linear mixed effects models adjusted for tidal volume, respiratory rate and respiratory rate/tidal volume. RESULTS: Flow Index was different at the three pressure support levels and all group comparisons were statistically significant. In all tested models, Flow Index was independently associated with patient effort (p < 0.001). Flow Index prediction of inspiratory effort agreed with esophageal pressure-based methods. CONCLUSIONS: Flow Index is associated with patient inspiratory effort during pressure support ventilation, and may provide potentially useful information for setting inspiratory support and monitoring patient-ventilator interactions.
BACKGROUND: The evaluation of patient effort is pivotal during pressure support ventilation, but a non-invasive, continuous, quantitative method to assess patient inspiratory effort is still lacking. We hypothesized that the concavity of the inspiratory flow-time waveform could be useful to estimate patient's inspiratory effort. The purpose of this study was to assess whether the shape of the inspiratory flow, as quantified by a numeric indicator, could be associated with inspiratory effort during pressure support ventilation. METHODS: Twenty-four patients in pressure support ventilation were enrolled. A mathematical relationship describing the decay pattern of the inspiratory flow profile was developed. The parameter hypothesized to estimate effort was named Flow Index. Esophageal pressure, airway pressure, airflow, and volume waveforms were recorded at three support levels (maximum, minimum and baseline). The association between Flow Index and reference measures of patient effort (pressure time product and pressure generated by respiratory muscles) was evaluated using linear mixed effects models adjusted for tidal volume, respiratory rate and respiratory rate/tidal volume. RESULTS: Flow Index was different at the three pressure support levels and all group comparisons were statistically significant. In all tested models, Flow Index was independently associated with patient effort (p < 0.001). Flow Index prediction of inspiratory effort agreed with esophageal pressure-based methods. CONCLUSIONS: Flow Index is associated with patient inspiratory effort during pressure support ventilation, and may provide potentially useful information for setting inspiratory support and monitoring patient-ventilator interactions.
Authors: Filippo Albani; Federica Fusina; Gianni Ciabatti; Luigi Pisani; Valeria Lippolis; Maria Elena Franceschetti; Alessia Giovannini; Rossella di Mussi; Francesco Murgolo; Antonio Rosano; Salvatore Grasso; Giuseppe Natalini Journal: Crit Care Date: 2021-12-15 Impact factor: 9.097