Abstract
The importance of perioperative respiration monitoring is highlighted by high incidences of postoperative respiratory complications unrelated to the original disease. The objectives of this pilot study were to (1) simultaneously acquire respiration rate (RR), tidal volume (TV), minute ventilation (MV), SpO2 and PetCO2 from patients in post-anesthesia care unit (PACU) and (2) identify a practical continuous respiration monitoring method by analyzing the acquired data in terms of their ability and reliability in assessing a patient’s respiratory status. Thirteen non-intubated patients completed this observational study. A portable electrical impedance tomography (EIT) device was used to acquire RREIT, TV and MV, while PetCO2, RRCap and SpO2 were measured by a Capnostream35. Hypoventilation and respiratory events, e.g., apnea and hypopnea, could be detected reliably using RREIT, TV and MV. PetCO2 and SpO2 provided the gas exchange information, but were unable to detect hypoventilation in a timely fashion. Although SpO2 was stable, the sidestream capnography using the oronasal cannula was often unstable and produced fluctuating PetCO2 values. The coefficient of determination (R2) value between RREIT and RRCap was 0.65 with a percentage error of 52.5%. Based on our results, we identified RR, TV, MV and SpO2 as a set of respiratory parameters for robust continuous respiration monitoring of non-intubated patients. Such a respiration monitor with both ventilation and gas exchange parameters would be reliable and could be useful not only for respiration monitoring, but in making PACU discharge decisions and adjusting opioid dosage on general hospital floor. Future studies are needed to evaluate the potential clinical utility of such an integrated respiration monitor.
Highlights
Respiratory depression and hypoventilation due to residual anesthetics and opioid administration cause hypoxemia and hypercapnia in patients in the post-anesthesia care unit (PACU) and general hospital floor (GHF), which may lead to permanent disability or life-threating complications[1,2,3,4,5]
The sidestream capnography with an oronasal cannula is used for nonintubated patients, its accuracy suffers due to the sampling tube obstruction, damping of air flow as the air passes through the tube, and cannula d isplacement[14,15]
We found from our data on 13 non-intubated patients in PACU that the R REIT derived from the respiratory volume signal (RVS) was able to track fast and slow changes in breathing patterns reliably
Summary
Respiratory depression and hypoventilation due to residual anesthetics and opioid administration cause hypoxemia and hypercapnia in patients in the post-anesthesia care unit (PACU) and general hospital floor (GHF), which may lead to permanent disability or life-threating complications[1,2,3,4,5]. In spite of a recent article reporting a pulse oximetry’s accuracy issue associated with race or skin c olor[12], it is commonly used to detect hypoxemia via measuring peripheral oxygen saturation (SpO2). It often generates false or delayed alarms[5,13]. For early detection of hypoventilation in non-intubated patients, Voscopoulos et al.[16] reported a respiration monitoring method using impedance plethysmography to measure RR, TV and MV. We used two independent respiration monitoring devices to simultaneously acquire ventilation and gas exchange parameters, i.e., RR, TV, MV, S pO2 and PetCO2, from non-intubated patients in PACU. We analyzed the acquired data and assessed their capability and reliability in assessing a patient’s respiratory status and identified a practical continuous respiration monitoring method for future clinical studies
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