Low minute ventilation episodes during anesthesia recovery following intraperitoneal surgery as detected by a non-invasive respiratory volume monitor

Introduction: Monitoring respiratory performance is a challenge. Use of secondary indicators like oxygen saturation (SpO 2 ) and capnography (EtCO 2 ) have introduced delay in diagnosis and can produce false alarms. EtCO 2 in non-intubated patients has been problematic. We compared performance of an EtCO 2 monitor to a respiratory volume monitor (RVM), which provides accurate (error <10%) measurements of minute ventilation (MV), tidal volume & respiratory rate, to assess changes in respiratory status in non-intubated subjects. Methods: Continuous RVM (ExSpiron, Respiratory Motion, Waltham, MA) and capnography data (Capnostream 20, SmartCapnoLine Plus & Filterline Set, Covidien, Mansfield, MA) were collected from 39 subjects. The relationship between EtCO 2 & MV for each patient was quantified & EtCO 2 sensitivity to MV changes and mean EtCO 2 values were compared across the two EtCO 2 sampling techniques (paired t-test). Results: A strong negative correlation between MV changes and EtCO 2 changes was found (similar between nasal sampling (NS) and in-line sampling (IS) ( -0.6 ±0.1 v -0.7±0.1 mmHg/(L/min), p>0.1, Fig 1A)). IS readings were higher than NS for each patient. In the same patients (normal breathing) the average IS EtCO 2 was 36.7 ±0.7 vs 33.7±0.6 mmHg for NS (p<0.01) despite larger MV (8.74 ±0.5 vs 7.0±0.5 L/min). Similar disparity was present during hypo & hyperventilation (Fig 1B&C). Regardless of sampling methodology, EtCO 2 displayed poor resolution in response to large swings in MV (13 & 14 mmHg in response to 17 & 21 fold increase in MV; IS & NS, respectively). Conclusions: Under controlled experimental conditions & with an in-line sensor capable of capturing 100% of exhaled air, EtCO 2 did not report large swings in MV with fidelity. Commonly used nasal sampling introduced a systematic bias that could further delay informing clinicians of dangerously low MV. RVM provides a direct measure of MV, eliminating the lag between a change in MV and secondary measurements.

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Abstract 19116: Assessment of Perioperative Minute Ventilation in Obese versus Non-Obese Patient Using a Non-Invasive Respiratory Volume Monitor

Circulation ◽

10.1161/circ.130.suppl_2.19116 ◽

2014 ◽

Vol 130 (suppl_2) ◽

Author(s):

Christopher Voscopoulos ◽

Jenny Freeman ◽

Kathleen Campbell ◽

Edward George

Keyword(s):

Minute Ventilation ◽

Obese Patients ◽

Metabolic Demand ◽

Respiratory Volume ◽

Non Invasive ◽

Indirect Measures ◽

Obesity Status ◽

Treatment Plans ◽

Orthopedic Patients ◽

Direct Measures

Introduction: Adequate respiration is critical to survival and can be influenced by opioids, sedatives and apnea. Direct monitoring of ventilation has previously not been available for non-intubated patients. Reliance on indirect measures (SpO2, RR) may delay needed interventions and obese patients may be at further risk. A non-invasive respiratory volume monitor (RVM) providing real-time direct measures of MV, TV & RR in non-intubated patients is used to assess respiratory status in obese and non-obese patients. Methods: Data collected from an impedance-based RVM (ExSpiron-1Xi, Respiratory Motion, Waltham, MA) in 62 orthopedic patients (65.4 ±12.0 yrs, BMI: 30.8 ±6.0 kg/m 2 ) before, during & after surgery (PACU arrival & discharge) were compared to predicted MV (MV PRED ) based on IBW. Ventilator MV (Apollo, Draeger, Telford, PA) during GA was assumed to be adjusted to maintain appropriate end-tidalCO 2 . Patients were stratified based on obesity status (cutoff BMI=30). The distributions of MV at various times were compared (non-obese vs obese) using an un-paired 1-sided t-test & a 2-sample F-test. Results: Despite similar MV PRED in both groups (6.2±0.2; 6.1±0.2 L/min, p>0.3) obese patients were managed at a higher MV during surgery (6.1±0.2; 5.3±0.2 L/min, p<0.01). MV differences were far greater preoperatively (9.7±0.4 vs. 6.7±0.3 L/min), at PACU arrival (11.4 ±1.2; 6.8±0.7 L/min) & discharge (7.7±0.5; 5.0±0.6 L/min, p<0.01 all, Fig 1). Patient-to-patient variability in MV was similar in both groups pre-op, but larger in obese patients. Even with the large average MV in obese patients, 6% of them left the PACU with MV<40% MV PRED . Conclusions: On average, obese patients have greater MV than predicted by IBW formula, likely due to greater metabolic demand. Post-op, obese patients have greater variability in ventilation when treated with standard opioid doses & may be at greater risk for hypoventilation. RVM can provide data for individualized treatment plans.

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Non-invasive respiratory volume monitoring for quantification of respiratory depression after benzodiazepine administration

Critical Care ◽

10.1186/cc14308 ◽

2015 ◽

Vol 19 (Suppl 1) ◽

pp. P228

Author(s):

G Mullen ◽

D Ladd

Keyword(s):

Respiratory Depression ◽

Respiratory Volume ◽

Non Invasive

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(129) The use of a non-invasive respiratory volume monitor to identify patients at high-risk for opioid-induced respiratory depression for a low-dose opioid regimen in the PACU

Journal of Pain ◽

10.1016/j.jpain.2015.01.043 ◽

2015 ◽

Vol 16 (4) ◽

pp. S8

Author(s):

C. Voscopoulos ◽

D. Ladd ◽

E. George

Keyword(s):

High Risk ◽

Respiratory Depression ◽

Low Dose ◽

Respiratory Volume ◽

Non Invasive

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Minute ventilation to carbon dioxide production ratio is a simple and non-invasive index of ventilatory inefficiency in mechanically ventilated patients: proof of concept

Intensive Care Medicine ◽

10.1007/s00134-017-4844-7 ◽

2017 ◽

Vol 43 (10) ◽

pp. 1542-1543

Author(s):

René López ◽

Iván Caviedes ◽

Jerónimo Graf

Keyword(s):

Carbon Dioxide ◽

Minute Ventilation ◽

Carbon Dioxide Production ◽

Proof Of Concept ◽

Mechanically Ventilated ◽

Mechanically Ventilated Patients ◽

Non Invasive ◽

Production Ratio ◽

Ventilated Patients

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Respiratory changes during adaptation to stress induced by movement restriction in rabbits

10.21203/rs.3.rs-16582/v1 ◽

2020 ◽

Author(s):

Jaime Villalba-Caloca ◽

José Luis Arreola-Ramírez ◽

Jesús Alquicira-Mireles ◽

Mario H. Vargas ◽

Verónica Carbajal-Salinas ◽

...

Keyword(s):

Minute Ventilation ◽

Respiratory Frequency ◽

Pulmonary Mechanics ◽

Movement Restriction ◽

Non Invasive ◽

Respiratory Parameters ◽

Invasive Method ◽

Parasympathetic Tone ◽

As Stress ◽

Lung Airways

Abstract Background Confinement inside a restricted space causing movement restriction is a stressful condition, potentially leading to spontaneous changes of respiratory parameters that are expected to return to normal values as the stress subsides. Barometric plethysmography is a non-invasive method to study surrogates of pulmonary mechanics in conscious animals enclosed into a plexiglass chamber. This chamber greatly restricts the animal movements but does not cause its immobilization. Methods Respiratory parameters from six rabbits were recorded during 90 min/day for 5 days while the animal was confined inside a plethysmographic chamber. Modifications of respiratory parameters were evaluated by dividing the total length of the recording in three 30-min periods. Results During the 90-min recording, enhanced pause (Penh, a lung resistance surrogate) showed a decreasing trend, coinciding with a decline of the mid-expiratory flow (an airway obstruction surrogate), and time of braking (an end-inspiratory glottis closure surrogate). Respiratory frequency increased from 346 to 363 breaths/min, coinciding with a progressive decline of tidal volume and minute ventilation. Because rabbit responses to stressful situations are predominantly parasympathetic in nature, an increased parasympathetic tone during the first minutes of confinement might explain the initially augmented lung, airways and glottis resistances, and these, in turn, could be responsible for the low initial respiratory frequency. Subsequent changes of these variables probably reflect progressively lower level of stress due to adaptation to the new environment. This pattern did not change in the 5 days studied. Conclusions We concluded that respiratory parameters in rabbits display subtle changes during the first 90 min of movement restriction, probably driven by an initially augmented parasympathetic tone due to stress, with subsequent normalization as stress diminished due to adaptation to the new environment.

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