Critical Care: ICU Management and Outcomes |

Respiratory Volume Monitoring for Assessment of Ventilation and RSBI Score Pre- and Post-Extubation FREE TO VIEW

Sarah Robison, MD; Daniel Eversole, PhD; Jose Diaz-Gomez, MD; John Moss, MD
Author and Funding Information

Respiratory Motion, Inc., Waltham, MA

Copyright 2016, American College of Chest Physicians. All Rights Reserved.

Chest. 2016;150(4_S):291A. doi:10.1016/j.chest.2016.08.304
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SESSION TITLE: ICU Management and Outcomes

SESSION TYPE: Original Investigation Slide

PRESENTED ON: Tuesday, October 25, 2016 at 08:45 AM - 10:00 AM

PURPOSE: Respiratory failure is the most common reason for ICU readmission. While multifactorial etiologies contribute, the final common pathway leading to respiratory decompensation often escapes early recognition due to generally insufficient respiratory monitoring in non-intubated patients. Current clinical practice relies on intermittent measurement of respiratory rate, subjective clinical assessment, and secondary indicators of respiratory status, like EtCO2 and SpO2. As a result, patients often spend extra time in the ICU as a precaution, and despite current practice recommendations for early extubation, clinicians often err of the side of caution and keep patients intubated longer than necessary. Clinicians often use quantitative measures like the rapid shallow breathing index (RSBI) in intubated patients as a predictor of patient-readiness for ventilator weaning and extubation. Here we evaluate the ability of a non-invasive Respiratory Volume Monitor (RVM) that provides quantitative measurements of minute ventilation (MV), tidal volume (TV) & respiratory rate (RR) for non-intubated patients to evaluate patients’ respiratory status, including RSBI pre- and post-extubation. We propose that RSBI may be useful in non-intubated patients when making decisions regarding reintubation or the implementation of non-invasive ventilation (NIV).

METHODS: RVM traces were continuously recorded from 6 ICU patients (age: 66 yrs, 47-93; BMI: 25.5 kg/m2, 22.0-31.0) beginning on arrival to ICU and terminating the earlier of 24 hours after extubation or discharge from the unit. Patients arrived intubated and sedated. The RVM was individually calibrated to each patient using MV data from the ventilator (Maquet, Getinge Group, Rastatt, Germany). MV, TV, RR and RSBI, were calculated from 30-sec respiratory segments. Predicted MV (MVPRED) for each patient was calculated based on Body Surface Area.

RESULTS: During the 30-min prior to extubation, patients maintained on average a MV of 100% ± 1% of MVPRED. Around the time of extubation, MV increased by 44% and during the next 30-min dropped by approximately 38%, subsequently recovering pre-extubation levels within 1 hour, driven primarily by changes in TV with a relatively constant RR. Within the same time period, RSBI scores trended downwards, consistently < 65 breaths/min/L along with reduced variability (pre vs. post- extubation RSBI: 54 ± 14 vs 44 ± 9 breaths/min/L). In patients with high pre-extubation RSBI (> 100), RSBI decreased more rapidly, again primarily due to changes in TV, rather than RR (136% TV vs 43% RR).

CONCLUSIONS: RVM monitoring provides a means to quantitatively monitor the respiratory status of non-intubated patients in the ICU, allowing clinicians to use familiar measurements (MV, TV, RR, RSBI) to detect respiratory compromise and assess adequacy of ventilation. The RVM detects real-time respiratory changes that would otherwise go unreported and may assist with decisions for airway management prior to the occurrence of adverse events.

CLINICAL IMPLICATIONS: For the first time, RSBI can be calculated for non-intubated patients and may be a useful predictor for re-intubation of patients at-risk of respiratory failure or for identification of patients requiring NIV.

DISCLOSURE: Daniel Eversole: Employee: Salary The following authors have nothing to disclose: Sarah Robison, Jose Diaz-Gomez, John Moss

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