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Respiratory Volume Monitoring Provides a Better Assessment of Respiratory Status Than Capnography-Based Respiratory Rate Monitoring During Upper Endoscopic Procedures FREE TO VIEW

Katherine Holley, DO; C. Marshall MacNabb; Paige Georgiadis, BS; Hayk Minasyan; Anurag Shukla; Diane Ladd, FNP-BC; Donald Mathews, MD
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West Virginia University, Morgantown, WV

Chest. 2014;146(4_MeetingAbstracts):560A. doi:10.1378/chest.1987864
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SESSION TITLE: Patient Safety Initiative Posters

SESSION TYPE: Original Investigation Poster

PRESENTED ON: Wednesday, October 29, 2014 at 01:30 PM - 02:30 PM

PURPOSE: Continuous respiratory monitoring during endoscopic procedures, while necessary, is often challenging. Current clinical practice based on oximetry and capnography may be able to detect severe respiratory compromise but lacks the fidelity to detect early onset of hypoventilation. It is generally accepted that EtCO2 measurements in non-intubated patients are often unreliable and as a result, the capnography-derived respiratory rate (RR) is often used as an indicator of respiratory sufficiency, since a direct measure of minute ventilation (MV) has been previously unavailable. A respiratory volume monitor (RVM) alongside capnography and oximetry monitors in the endoscopy suite was studied.

METHODS: Continuous respiratory traces were collected from 51 patients (age: 54 ± 5 yrs, BMI: 28 ± 2 kg/m2) undergoing upper endoscopy (EGD and ERCP) under procedural sedation, using an impedance-based RVM (ExSpiron, Respiratory Motion, Inc., Waltham, MA). Standard oximetry, capnography, heart rate (HR), and blood pressure (BP) data were automatically recorded during the procedure. Here we evaluated the frequency of available capnography and oximetry measurements as well as the ability of RR to predict inadequate ventilation (MV < 40% MVBASELINE).

RESULTS: In this cohort only 59% of the automatically recorded HR and BP measurements had a corresponding EtCO2 measurement (18% of these measurements were outside a physiologically-relevant range) and only 37% had a corresponding RR from the capnograph. Meanwhile, the RVM reported a RR throughout 97% of the monitored period. Further analysis showed that while MV and RR are functionally related, the correlation between low RR and low MV is weak (r=0.05). In fact, a simple threshold alarm based on RR alone (set at RR<6 b/min) would fail to detect more than 80% of all inadequate ventilation events.

CONCLUSIONS: This study confirmed the frequent lack of meaningful EtCO2 data in patients undergoing procedures around the airway such as upper endoscopy. Importantly, we also demonstrated unreliability of the corresponding capnography-based RR. Even when available, the RR measurements were a weak predictor of a patient’s overall respiratory status.

CLINICAL IMPLICATIONS: The RVM can provide continuous MV and RR measurements, which characterize respiratory status better than RR alone giving providers a truer picture of respiratory status which can allow for timely interventions and improve patient safety.

DISCLOSURE: C. Marshall MacNabb: Employee: Respiratory Motion, Inc. Diane Ladd: Employee: Respiratory Motion, Inc. The following authors have nothing to disclose: Katherine Holley, Paige Georgiadis, Hayk Minasyan, Anurag Shukla, Donald Mathews

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