Assessment of perioperative minute ventilation in obese versus non-obese patients with a non-invasive respiratory volume monitor

Jaideep H Mehta; Davide Cattano; Jordan B Brayanov; Edward E George

doi:10.1186/s12871-017-0352-0

Assessment of perioperative minute ventilation in obese versus non-obese patients with a non-invasive respiratory volume monitor

BMC Anesthesiol. 2017 Apr 26;17(1):61. doi: 10.1186/s12871-017-0352-0.

Authors

Jaideep H Mehta¹, Davide Cattano¹, Jordan B Brayanov², Edward E George³

Affiliations

¹ University of Texas Medical School at Houston, 6431 Fannin Street, Houston, TX, 77030, USA.
² Respiratory Motion Inc., 411 Waverley Oaks Rd #150, Waltham, MA, 02452, USA. Jordan.Brayanov@respiratorymotion.com.
³ Massachusetts General Hospital, Harvard Medical School, 55 Fruit St, Boston, MA, 02114, USA.

Abstract

Background: Monitoring the adequacy of spontaneous breathing is a major patient safety concern in the post-operative setting. Monitoring is particularly important for obese patients, who are at a higher risk for post-surgical respiratory complications and often have increased metabolic demand due to excess weight. Here we used a novel, noninvasive Respiratory Volume Monitor (RVM) to monitor ventilation in both obese and non-obese orthopedic patients throughout their perioperative course, in order to develop better monitoring strategies.

Methods: We collected respiratory data from 62 orthopedic patients undergoing elective joint replacement surgery under general anesthesia using a bio-impedance based RVM with an electrode PadSet placed on the thorax. Patients were stratified into obese (BMI ≥ 30) and non-obese cohorts and minute ventilation (MV) at various perioperative time points was compared against each patient's predicted minute ventilation (MV_PRED) based on ideal body weight (IBW) and body surface area (BSA). The distributions of MV measurements were also compared across obese and non-obese cohorts.

Results: Obese patients had higher MV than the non-obese patients before, during, and after surgery. Measured MV of obese patients was significantly higher than their MV_PRED from IBW formulas, with BSA-based MV_PRED being a closer estimate. Obese patients also had greater variability in MV post-operatively when treated with standard opioid dosing.

Conclusions: Our study demonstrated that obese patients have greater variability in ventilation post-operatively when treated with standard opioid doses, and despite overall higher ventilation, many of them are still at risk for hypoventilation. BSA-based MV_PRED formulas may be more appropriate than IBW-based ones when estimating the respiratory demand of obese patients. The RVM allows for the continuous and non-invasive assessment of respiratory function in both obese and non-obese patients.

Keywords: Minute ventilation; Obesity; Opioids; Perioperative safety; Respiratory monitoring; Respiratory requirements.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Aged
Analgesics, Opioid / administration & dosage
Analgesics, Opioid / adverse effects
Anesthesia, General
Arthroplasty, Replacement
Case-Control Studies
Female
Humans
Male
Monitoring, Physiologic*
Obesity / physiopathology*
Patient Safety
Pulmonary Ventilation / physiology*
Respiration*
Respiratory Insufficiency / physiopathology

Substances

Analgesics, Opioid