Non-contact physiological monitoring of post-operative patients in the intensive care unit

Prolonged non-contact camera-based monitoring in critically ill patients presents unique challenges, but may facilitate safe recovery. A study was designed to evaluate the feasibility of introducing a non-contact video camera monitoring system into an acute clinical setting. We assessed the accuracy and robustness of the video camera-derived estimates of the vital signs against the electronically-recorded reference values in both day and night environments. We demonstrated non-contact monitoring of heart rate and respiratory rate for extended periods of time in 15 post-operative patients. Across day and night, heart rate was estimated for up to 53.2% (103.0 h) of the total valid camera data with a mean absolute error (MAE) of 2.5 beats/min in comparison to two reference sensors. We obtained respiratory rate estimates for 63.1% (119.8 h) of the total valid camera data with a MAE of 2.4 breaths/min against the reference value computed from the chest impedance pneumogram. Non-contact estimates detected relevant changes in the vital-sign values between routine clinical observations. Pivotal respiratory events in a post-operative patient could be identified from the analysis of video-derived respiratory information. Continuous vital-sign monitoring supported by non-contact video camera estimates could be used to track early signs of physiological deterioration during post-operative care.

Modelling the direct virus exposure risk associated with respiratory events

The outbreak of the COVID-19 pandemic highlighted the importance of accurately modelling the pathogen transmission via droplets and aerosols emitted while speaking, coughing and sneezing. In this work, we present an effective model for assessing the direct contagion risk associated with these pathogen-laden droplets. In particular, using the most recent studies on multi-phase flow physics, we develop an effective yet simple framework capable of predicting the infection risk associated with different respiratory activities in different ambient conditions. We start by describing the mathematical framework and benchmarking the model predictions against well-assessed literature results. Then, we provide a systematic assessment of the effects of physical distancing and face coverings on the direct infection risk. The present results indicate that the risk of infection is vastly impacted by the ambient conditions and the type of respiratory activity, suggesting the non-existence of a universal safe distance. Meanwhile, wearing face masks provides excellent protection, effectively limiting the transmission of pathogens even at short physical distances, i.e. 1 m.

Postoperative Respiratory Compromise following Cesarean Birth: The Impact of Obesity and Systemic Opioids

Objective The aim of this study was to measure the effect of obesity and systemic opioids on respiratory events within the first 24 hours following cesarean. Methods Opioid-naive women undergoing cesarean between January 2016 and December 2017 were included in this retrospective cohort study. The primary outcome was the proportion of women experiencing at least one composite respiratory outcome (oxygen saturation less than 95% lasting 30+ seconds or need for respiratory support) within 24 hours of cesarean. The impact of obesity and total systemic opioid dose in 24 hours (measured in morphine milligram equivalents [MMEs]) on the composite respiratory compromise outcome were evaluated. Results Of 2,230 cesarean births, 790 women had at least one composite respiratory event. Predictors of the composite respiratory outcome included body mass index (BMI) as a continuous variable (odds ratio = 1.063 for every one unit increase in BMI [95% confidence interval (CI): 1.021–1.108], p = 0.003), and MME (odds ratio = 1.005 [95% CI: 1.002–1.008], p = 0.003), adjusting for magnesium sulfate use. The interaction between obesity and opioid dose demonstrated an odds ratio of 1.000 (95% CI: 0.999–1.000, p = 0.030). Conclusion The proportion of women experiencing respiratory events following cesarean birth increases with the degree of obesity and opioid dose. Key Points

Association Between Arousals During Sleep and Hypertension Among Patients With Obstructive Sleep Apnea

Background Sleep fragmentation induced by repetitive arousals is a hallmark of obstructive sleep apnea (OSA). Sleep fragmentation has been linked to hypertension in community‐based studies, but it is unclear if this association is manifest in OSA. We aimed to explore whether frequent arousals from sleep modify the relationship between OSA and prevalent hypertension. Methods and Results A total of 10 102 patients with OSA and 1614 primary snorers were included in the study. Hypertension was defined on either direct blood pressure measures or diagnosis by a physician. Spontaneous, respiratory, and movement arousals were derived by polysomnography. Logistic regression models were used to estimate the associations between arousals and prevalent hypertension in patients with OSA and primary snorers. For every 10‐unit increase of total arousal index, odds of hypertension significantly increased in both the total sample (odds ratio [OR], 1.08; 95% CI, 1.03–1.14; P =0.002) and patients with OSA (OR, 1.10; 95% CI, 1.04–1.16; P <0.001), but not in the primary snoring group. Total arousal index was significantly associated with systolic blood pressure and diastolic blood pressure in the total sample (β=0.05 and β=0.06; P <0.001) and in patients with (β=0.05 and β=0.06; P <0.01), but not in primary snorers. In addition, a greater influence of respiratory events with arousals than respiratory events without arousals on blood pressure in OSA was also noted. Results were independent of confounders, including apnea‐hypopnea index and nocturnal hypoxemia. Conclusions We conclude that repetitive arousals from sleep are independently associated with prevalent hypertension in patients with OSA.

Positional Therapy in a Patient With Refractory Treatment-Emergent Central Sleep Apnea

Treatment-emergent central sleep apnea (TE-CSA) is commonly encountered during the treatment for obstructive sleep apnea (OSA) with positive airway pressure (PAP) and usually remains self-limited. Persistent TE-CSA is sporadically seen with PAP therapy and has only rarely been described with hypoglossal nerve stimulation (HGNS). We report the case of a 60-year-old female patient with moderate OSA that progressed to TE-CSA with PAP therapy. A prolonged trial with PAP therapy was limited because the patient experienced recurrent aerophagia and subsequently underwent HGNS implantation. HGNS titration led to improved control of the patient’s OSA, but TE-CSA recurred and demonstrated a strong positional component. Lateral positional therapy was implemented with adequate control of respiratory events. TE-CSA can persist throughout different treatment modalities, including HGNS. The patient’s successful lateral sleep therapy for persistent and positionally exacerbated TE-CSA demonstrates the benefit of a well-known sleep apnea treatment for this poorly understood condition.

Automatic detection of respiratory events during sleep from Polysomnography data using Layered Hidden Markov Model

Objective. Sleep apnea is a serious respiratory disorder, which is associated with increased risk factors for cardiovascular disease. Many studies in recent years have been focused on automatic detection of sleep apnea from polysomnography (PSG) recordings, however, detection of subtle respiratory events named Respiratory Event Related Arousals (RERAs) that do not meet the criteria for apnea or hypopnea is still challenging. The objective of this study was to develop automatic detection of sleep apnea based on Hidden Markov Models (HMMs) which are probabilistic models with the ability to learn different dynamics of the real time-series such as clinical recordings. Approach. In this study, a hierarchy of HMMs named Layered HMM was presented to detect respiratory events from PSG recordings. The recordings of 210 PSGs from Massachusetts General Hospital’s database were used for this study. To develop detection algorithms, extracted feature signals from airflow, movements over the chest and abdomen, and oxygen saturation in blood (SaO2) were chosen as observations. The respiratory disturbance index (RDI) was estimated as the number of apneas, hypopneas, and RERAs per hour of sleep. Main results. The best F1 score of the event by event detection algorithm was between 0.22±0.16 and 0.70±0.08 for different groups of sleep apnea severity. There was a strong correlation between the estimated and the PSG-derived RDI (R2=0.91, p<0.0001). The best recall of RERA detection was achieved 0.45±0.27. Significance. The results showed that the layered structure can improve the performance of the detection of respiratory events during sleep.

Cardio-Respiratory Events and Food Autonomy Responses to Early Uni-Modal Orofacial Stimulation in Very Premature Babies: A Randomized, Controlled Study

Uni-modal orofacial stimulation (OFS) for preventing very preterm infants’ oral disorders is highly controversial. Our study sought to demonstrate that OFS reduced cardio-respiratory events and improved food autonomy in a population of very preterm infants. Our study was randomized, controlled, prospective, and unicentric. The preterm included were born between 26–29 weeks gestational age (GA) with a corrected postnatal age <33 weeks GA. They were randomized into two groups: the experimental group underwent OFS, according to a protocol established, over 10 consecutive days, and the control group underwent no OFS. The primary outcome was the number of cardiorespiratory events: apnea–bradycardia (with or without desaturations) or number of isolated desaturations, which were evaluated at four separate times. Measurements occurred during the first, fourth and eighth independent feedings. Seventeen patients were included in the experimental group and 18 in the control group. The number of cardiorespiratory events for all independent feeding times was significantly reduced in the OFS group (p = 0.003) with univariate analysis, but not with multivariable analysis. The quantity of milk ingested during the first autonomous feeding was higher in the experimental group. The acquisition of food autonomy and the duration of hospitalization were similar in the two groups. While our study does not affirm that an early unimodal OFS improves premature infants’ cardiorespiratory evolution and/or the acquisition of food autonomy, it does indicate an improved food efficiency during their first autonomous feedings.

Complications Associated With Removal of Airway Devices Under Deep Anesthesia In Children: An Analysis of The Wake Up Safe Database

Background: Previous studies examining removal of endotracheal tubes and supraglottic devices under deep anesthesia were underpowered to identify rare complications. This study sought to report all adverse events associated with this practice found in a large national database of pediatric anesthesia adverse events.Methods: An extract of an adverse events database created by the Wake Up Safe database, a multi-institutional pediatric anesthesia quality improvement initiative, was performed for this study. It was screened to identify anesthetics with variables indicating removal of airway devices under deep anesthesia. Three anesthesiologists screened the data to identify events where this practice possibly contributed to the event. Event data was extracted and collated. Results: 102 events met screening criteria and 66 met inclusion criteria. Two cardiac etiology events were identified, one of which resulted in the patient’s demise. The remaining 97% of events were respiratory in nature (64 events), including airway obstruction, laryngospasm, bronchospasm and aspiration. Some respiratory events consisted of multiple distinct events in series. Nineteen respiratory events resulted in cardiac arrest (29.7%) of which 15 (78.9%) were deemed preventable by local anesthesiologists performing independent review. Respiratory events resulted in intensive care unit admission (37.5%), prolonged intubation and temporary neurologic injury but no permanent harm. Provider and patient factors were root causes in most events. Upon investigation, areas for improvement identified included improving patient selection, ensuring monitoring, availability of intravenous access, and access to emergency drugs and equipment until emergence.Conclusions: Serious adverse events have been associated with this practice, but no respiratory events were associated with long-term harm.

Predictors of changes in cerebral perfusion and oxygenation during obstructive sleep apnea

Obstructive sleep apnea syndrome (OSAS) is a common sleep disorder. Severe OSAS defined as apnea–hypopnea index (AHI) ≥ 30/h is a risk factor for developing cerebro-cardiovascular diseases. The mechanisms of how repetitive sleep apneas/hypopneas damage cerebral hemodynamics are still not well understood. In this study, changes in blood volume (BV) and oxygen saturation (StO2) in the left forehead of 29 newly diagnosed severe OSAS patients were measured by frequency-domain near-infrared spectroscopy during an incremental continuous positive airway pressure (CPAP) titration protocol together with polysomnography. The coefficients of variation of BV (CV-BV) and the decreases of StO2 (de-StO2) of more than 2000 respiratory events were predicted using linear mixed-effect models, respectively. We found that longer events and apneas rather than hypopneas induce larger changes in CV-BV and stronger cerebral desaturation. Respiratory events occurring during higher baseline StO2 before their onsets, during rapid-eye-movement sleep and those associated with higher heart rate induce smaller changes in CV-BV and de-StO2. The stepwise increased CPAP pressures can attenuate these changes. These results suggest that in severe OSAS the length and the type of respiratory event rather than widely used AHI may be better parameters to indicate the severity of cerebral hemodynamic changes.

Apnea–hypopnea index severity as an independent predictor of post-tonsillectomy respiratory complications in pediatric patients: A retrospective study

Introduction Despite the presence of clinical practice guidelines for overnight admission of pediatric patients following adenotonsillectomy, variance in practice patterns exists between pediatric otolaryngologists. The purpose of this study is to examine severity of apnea–hypopnea index (AHI) as an independent predictor of postoperative respiratory complications in children undergoing adenotonsillectomy. Methods Retrospective chart review of all children undergoing adenotonsillectomy at a large tertiary referral center between January 2015 and December 2019 who underwent preoperative polysomnography and were admitted for overnight observation. Charts were reviewed for total adverse events and respiratory events occurring during admission. Results Overall, respiratory events were seen in 50.6% of patients with AHI ≥10 and in 39.6% of patients with AHI <10. The overall mean AHI was 19.2, with a mean of 28.1 in the AHI ≥10 subgroup vs 4.6 in the AHI <10 subgroup. There was no statistical correlation or increased risk between an AHI ≥10 and having a pure respiratory event, with a relative risk of 1.19 (.77–1.83, P = .43). There was a statistically significant difference between the mean AHI of those with any adverse event and those without (21.6 vs 13.4, P = .008). There is additionally an increased risk of any event with an AHI over 10, with a relative risk of 1.51 (1.22–1.88, P < .0001). Conclusion Preoperative AHI of 10 events per hour was not a predictor of postoperative respiratory complications. However, there was a trend for those with a higher AHI requiring additional supportive measures or a prolonged stay. Practitioners should always use their best judgment in deciding whether a child warrants postoperative admission following adenotonsillectomy.