Frequent respiratory events in postoperative patients aged 60 years and above

Effect of averaging time and respiratory pause time on the measurement of acoustic respiration rate monitoring

BACKGROUND

Acoustic respiration rate (RRa) monitoring is a method of continuously measuring respiratory rate using a signal from an acoustic transducer placed over the airway. The purpose of the present study is to examine how the averaging time and respiratory pause time settings of an RRa monitor affect the detection time of sudden respiratory rate changes.

METHODS

A total of 40 healthy adult volunteers were included in the study. First, we measured the apnea detection time (apnea test) by dividing them into two groups (N = 20 each), one with a respiratory pause time setting of 20 s and the other with 40 s. Each group performed two apnea tests with an averaging time setting of 10 and 30 s. Next, we measured the tachypnea detection time (tachypnea test) for half of the subjects (N = 20) with two averaging time settings of 10 and 30 s. For each test, three measurements were taken, and the average of the three measurements was recorded.

RESULTS

There was no significant difference in the apnea detection time between the averaging time set at 10 and 30 s regardless of whether the respiratory pause time was set at 20 or 40 s. However, the apnea detection time was significantly shorter with the respiratory pause time of 20 s than 40 s, regardless of whether the averaging time was set at 10 or 30 s (p < 0.001). The tachypnea detection time was shorter with the averaging time of 10 s than 30 s (p < 0.001). Furthermore, the apnea detection time and tachypnea detection time were much longer than the actual settings.

CONCLUSIONS

The results of the current study show that in the measurement of RRa, the apnea detection time is more affected by the respiratory pause time setting than the averaging time setting; however, the tachypnea detection time is significantly affected by the averaging time setting.

Hypoventilation in the PACU is associated with hypoventilation in the surgical ward: Post-hoc analysis of a randomized clinical trial

OBJECTIVE

To evaluate the association between early postoperative hypoventilation in the last hour of the post-anesthesia care unit (PACU) stay and hypoventilation during the rest of the first 48 postoperative hours in the surgical ward.

DESIGN

Sub-analysis of a clinical trial.

SETTING

PACU and surgical wards of a single medical center.

PATIENTS

Adults having abdominal surgery under general anesthesia.

INTERVENTIONS

Monitoring with a respiratory volume monitor from admission to PACU until the earlier of 48 h after surgery or discharge.

MEASUREMENTS

The exposure was having at least one low minute-ventilation (MV) event during the last hour of PACU stay, defined as MV lower than 40% the predicted value lasting at least 1 min. The primary outcome was low MV events lasting at least 2 min during the rest of the first 48 postoperative hours, while in the surgical ward. The secondary outcome was the rate of low MV events per monitored hour.

MAIN RESULTS

Data of 292 patients were analyzed, of which 20 (6.8%) patients had a low MV event in PACU. Low MV events in the surgical ward were found in 81 (28%) patients. All patients who had low MV events in PACU had events again in the ward, while 61/272 (22%) had an event in the ward but not in PACU. The incidence rate of low MV events per hour was 24 (95% CI: 13, 46) among patients having an event in the PACU, and 2 (1, 4) among those who did not.

CONCLUSIONS

In adults recovering from abdominal surgery, events of hypoventilation during the first postoperative hour are associated with similar events during the rest of the first 48 postoperative hours, with positive predictive value approaching 100%. Sixty-one patients had ward hypoventilation that was not preceded by hypoventilation in PACU.

Effects of opioid-free anesthesia on postoperative morphine consumption after bariatric surgery

STUDY OBJECTIVES

The objective of this study was to determine whether postoperative morphine requirement in obese patients undergoing laparoscopic bariatric surgery was reduced by opioid-free anesthesia (OFA), as compared to an anesthetic strategy using opioids (opioid balanced anesthesia (OBA)) and to investigate the differences that may exist between the use of clonidine and dexmedetomidine in the context of OFA.

DESIGN

Retrospective cohort study.

SETTING

Academic medical center in Lyon, France.

PATIENTS

257 patients who underwent laparoscopic bariatric surgery between March 2017 and March 2019. 77 patients were included in the OBA group and 180 in the OFA group. The OFA group was subdivided in two: 90 patients received OFA with clonidine (OFAC) and 90 received OFA with dexmedetomidine (OFAD).

MEASUREMENTS

Proportion of patients who did not receive morphine during the first 24 postoperative hours.

MAIN RESULTS

During the first 24 postoperative hours, the proportion of patients who did not require morphine was significantly higher in the OFA (87%) than in the OBA (52%) group (OR: 6.31; 95% CI [3.38; 11.80], P < 0.001). This difference remained significant after adjustment for age, body mass index, sex, type and duration of surgery (OR: 7.99; 95% CI [4.05; 16.48], P < 0.001). A greater proportion of patients in the OFAD (93%) than in the OFAC group (81%, P = 0.026) did not receive morphine during the same period.

CONCLUSIONS

OFA is associated with a lower morphine requirement than with OBA during the first 24 h after bariatric surgery. In addition, OFAD seems to be more effective than OFAC in order to reduce morphine consumption.

Effects of the intermediate care unit on the oldest-old general surgical patients: a retrospective, pre- and postintervention study

BACKGROUND

Whether the intermediate care unit (IMCU) is beneficial for the oldest-old (aged ≥ 80 years) general surgical patients still remains unknown. We aimed to investigate the impacts of IMCU on the clinical outcomes and cost in this population.

METHODS

A retrospective, pre- and postintervention study was performed in this population in a university teaching hospital. The primary outcome was the occurrence of life-threatening complications including death or unplanned ICU admission after the surgeries. Secondary outcomes included the comparisons of the hospitalization expenses, the hospital length of stay (LOS) and the postoperative LOS between the pre-IMCU group and the IMCU group.

RESULTS

Two hundred and seventeen patients were enrolled, including 98 in the pre-IMCU group and 119 in the IMCU group. After the introduction of IMCU, the occurrence of life-threatening complications significantly dropped from 11.2 to 2.5% (P = 0.012). The total hospitalization expenses showed a nonsignificant decreasing trend in the IMCU group (pre-IMCU group: 85856.3 ± 66583.7 RMB vs IMCU group: 78936.4 ± 36710.4 RMB). The treatment fee was much lower in the IMCU group (IMCU group: 4930.0 ± 4280.2 RMB vs pre-IMCU group: 7378.2 ± 10096.7 RMB, P = 0.017). Both the hospital LOS (IMCU group: 20.3 ± 10.3 days vs pre-IMCU group: 19.5 ± 9.0 days) and the postoperative hospital LOS (IMCU group: 12.0 ± 8.1 days vs pre-IMCU group: 11.2 ± 7.0 days) were not statistically different in the two groups.

CONCLUSIONS

The allocation of the oldest-old surgical patients who do not need organ support therapy in the ICU to IMCU rather than in the standard wards was associated with a significant decrease in postoperative life-threatening complications and treatment fee.

TRIAL REGISTRATION

This study was registered at https://www.chictr.org.cn (ChiCTR2000030639).

Postoperative respiratory state assessment using the Integrated Pulmonary Index (IPI) and resultant nurse interventions in the post-anesthesia care unit: a randomized controlled trial

Although postoperative adverse respiratory events, defined by a decrease in respiratory rate (RR) and/or a drop in oxygen saturation (SpO₂), occur frequently, many of such events are missed. The purpose of the current study was to assess whether continuous monitoring of the integrated pulmonary index (IPI), a composite index of SpO₂, RR, end-tidal PCO₂ and heart rate, alters our ability to identify and prevent adverse respiratory events in postoperative patients. Eighty postoperative patients were subjected to continuous respiratory monitoring during the first postoperative night using RR and pulse oximetry and the IPI monitor. Patients were randomized to receive intervention based on standard care (observational) or based on the IPI monitor (interventional). Nurses were asked to respond to adverse respiratory events with an intervention to improve the patient’s respiratory condition. There was no difference in the number of patients that experienced at least one adverse respiratory event: 21 and 16 in observational and interventional group, respectively (p = 0.218). Compared to the observational group, the use of the IPI monitor led to an increase in the number of interventions performed by nurses to improve the respiratory status of the patient (average 13 versus 39 interventions, p < 0.001). This difference was associated with a significant reduction of the median number of events per patient (2.5 versus 6, p < 0.05) and a shorter median duration of events (62 s versus 75 s, p < 0.001). The use of the IPI monitor in postoperative patients did not result in a reduction of the number of patients experiencing adverse respiratory events, compared to standard clinical care. However, it did lead to an increased number of nurse interventions and a decreased number and duration of respiratory events in patients that experienced postoperative adverse respiratory events.

Wearable Multimodal Stethoscope Patch for Wireless Biosignal Acquisition and Long-Term Auscultation

Detecting critical events in postoperative care and improving comfort, costs and availability in sleep assessment are two of many areas in which wearable biosignal acquisition can be a viable tool. Modern sensors as well as patch and textile integration facilitate unobtrusive biosignal acquisition, yet placing sensors at different locations across the body is still prevailing. Actigraphy and the electrocardiogram (ECG) are commonly integrated modalities. The stethoscope however, despite its wide range of applications, has been neglected from these developments. The introduction of digital stethoscopes, recently led to an objectification and increased interest in the field. We present the prototype of a wearable, Bluetooth 5.0 LE enabled multimodal sensor patch combining five modalities: MEMS stethoscope, ambient noise sensing, ECG, impedance pneumography (IP) and 9-axial actigraphy. The system alleviates the need for sensors at different body positions and enables long-term auscultation. Using high sampling rates and online synchronization, multimodal sensor fusion becomes feasible. The patch measures 70 mm x 60 mm and is attached using three 24 mm Ag/AgCl electrodes. High quality cardiac and pulmonary auscultation as well as ECG and IP acquisition are demonstrated. We derived respiration surrogates with linear correlations to a reference exceeding 0.91 and conclude that the system can be utilized in fields requiring unobtrusive yet high quality signal acquisition. Future research will include the integration of additional sensors and further size reduction.

Wearable Cardiorespiratory Monitoring Employing a Multimodal Digital Patch Stethoscope: Estimation of ECG, PEP, LVETand Respiration Using a 55 mm Single-Lead ECG and Phonocardiogram

Cardiovascular diseases are the main cause of death worldwide, with sleep disordered breathing being a further aggravating factor. Respiratory illnesses are the third leading cause of death amongst the noncommunicable diseases. The current COVID-19 pandemic, however, also highlights the impact of communicable respiratory syndromes. In the clinical routine, prolonged postanesthetic respiratory instability worsens the patient outcome. Even though early and continuous, long-term cardiorespiratory monitoring has been proposed or even proven to be beneficial in several situations, implementations thereof are sparse. We employed our recently presented, multimodal patch stethoscope to estimate Einthoven electrocardiogram (ECG) Lead I and II from a single 55 mm ECG lead. Using the stethoscope and ECG subsystems, the pre-ejection period (PEP) and left ventricular ejection time (LVET) were estimated. ECG-derived respiration techniques were used in conjunction with a novel, phonocardiogram-derived respiration approach to extract respiratory parameters. Medical-grade references were the SOMNOmedics SOMNO HDTM and Osypka ICON-CoreTM. In a study including 10 healthy subjects, we analyzed the performances in the supine, lateral, and prone position. Einthoven I and II estimations yielded correlations exceeding 0.97. LVET and PEP estimation errors were 10% and 21%, respectively. Respiratory rates were estimated with mean absolute errors below 1.2 bpm, and the respiratory signal yielded a correlation of 0.66. We conclude that the estimation of ECG, PEP, LVET, and respiratory parameters is feasible using a wearable, multimodal acquisition device and encourage further research in multimodal signal fusion for respiratory signal estimation.

Estimation of respiratory rate using infrared video in an inpatient population: an observational study

Respiratory rate (RR) is one of the most sensitive markers of a deteriorating patient. Despite this, there is significant inter-observer discrepancy when measured by clinical staff, and modalities used in clinical practice such as ECG bioimpedance are prone to error. This study utilized infrared thermography (IRT) to measure RR in a critically ill population in the Intensive Care Unit. This study was carried out in a Single Hospital Centre. Respiratory rate in 27 extubated ICU patients was counted by two observers and compared to ECG Bioimpedance and IRT-derived RR at distances of 0.4-0.6 m and > 1 m respectively. IRT-derived RR using two separate computer vision algorithms outperformed ECG derived RR at distances of 0.4-0.6 m. Using an Autocorrelation estimator, mean bias was - 0.667 breaths/min. Using a Fast Fourier Transform estimator, mean bias was - 1.000 breaths/min. At distances greater than 1 m no statistically significant signal could be obtained. Over all frequencies, there was a significant relationship between the RR estimated using IRT and via manual counting, with Pearson correlation coefficients between 0.796 and 0.943 (p < 0.001). Correlation between counting and ECG-derived RR demonstrated significance only at > 19 bpm (r = 0.562, p = 0.029). Overall agreement between IRT-derived RR at distances of 0.4-0.6 m and gold standard counting was satisfactory, and outperformed ECG derived bioimpedance. Contactless IRT derived RR may be feasible as a routine monitoring modality in wards and subacute inpatient settings.

Estimating Respiratory Rate in Post-Anesthesia Care Unit Patients Using Infrared Thermography: An Observational Study

The post-anesthesia care unit (PACU) is the central hub for recovery after surgery, especially when the surgery is performed under general anesthesia. Aside from clinical aspects, respiratory impairment is one of the major causes of morbidity and affected recovery in the PACU and should therefore be monitored. In previous studies, infrared thermography was applied to assess the breathing rate (BR) of healthy volunteers. Here, the transferability of published methods for postoperative patients in the PACU was examined. Video recordings of 28 patients were acquired using a long-wave infrared camera, and analyzed offline. For validation purposes, BRs derived from body surface electrocardiography were measured simultaneously. In general, a close agreement between the two techniques (r = 0.607, p = 0.002 upon arrival, and r = 0.849, p < 0.001 upon discharge from the PACU) was obtained. In conclusion, the algorithm was demonstrated to be feasible and reliable under these challenging conditions.