Study objective: Assess the utility of a respiratory volume monitor (RVM) to reduce the incidence of low minute ventilation events in procedural sedation.
Design: Randomized control trial SETTING: Endoscopy suite PATIENTS: Seventy-three total patients (ASA Physical Status 1-3) undergoing upper endoscopies were analyzed.
Intervention: Patients were randomized into two groups using a computer generated randomization table: Control (n=41): anesthesia provider was unable to see the screen of the RVM; RVM (n=32): anesthesia provider had access to RVM data to assist with management of the case.
Measurements: Minute ventilation (MV), tidal volume, and respiratory rate were continuously recorded by the RVM. MV is presented as percent of Baseline MV (MVBaseline), defined during a 30s period of quiet breathing prior to sedation. We defined Low MV as MV<40% MVBaseline, and calculated the percentage of procedure spent with Low MV. Patients in the RVM group were stratified based on whether the anesthesiologist rated the RVM as "not useful", "somewhat useful", or "very useful" during the case.
Main results: Control patients experienced twice as much Low MV compared to RVM patients (15.3±2.8% vs. 7.1±1.4%, P=0.020). The "not useful" (13.7±3.8%) group showed no improvement over the Control group (p=0.81). However, both the "very useful" (4.7±1.4%) and "somewhat useful" (4.9±1.7%) groups showed significant improvement over the "not useful" group (p<0.05).
Conclusions: Patients in the Control group spent more than double the amount of time with Low MV compared to the RVM group. This difference became more pronounced when the anesthesiologist found the RVM useful for managing care, lending credibility to the usage of minute ventilation monitoring in procedural sedation.
Keywords: Conscious sedation; Endoscopy; Medical device, ventilation; Noninvasive respiratory volume monitor; Respiratory insufficiency.
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