The Human Dive Reflex During Consecutive Apnoeas in Dry and Immersive Environments: Magnitude and Synchronicity

Introduction: The human dive reflex (HDR), an O2 conserving reflex, is characterised by an interplay of central parasympathetic and peripheral sympathetic reactions, which are presumed to operate independently of each other. The HDR is fully activated during apnoea with facial immersion in water and complete immersion in water is thought to increase the magnitude of HDR during consecutive apnoeas. A comparison of HDR activity between consecutive apnoeas in full-body immersion with consecutive apnoeas in dry conditions has not been fully explored. Also, the interplay between parasympathetic and sympathetic reactions involved in the HDR has not been thoroughly analysed.Methods: 11 human volunteers performed 3 consecutive 60 s apnoeas with facial immersion in dry conditions (FIDC) and 3 consecutive apnoeas with facial immersion in full immersion (FIFI). Heart rate (HR), R-R interval (RRI), finger pulse amplitude (FPA), splenic width (SW) and SpO2 were all measured before, during and after apnoeas. A one-way ANOVA using Dunn’s post hoc test was performed to assess HDR activity, and a Pearson’s correlation test was performed to assess HDR synchronisation between physiological parameters during both conditions.Results: Although HDR activity was not significantly different between both conditions, HR and RRI showed progressively greater changes during FIFI compared with FIDC, while SW and FPA changes were relatively equivalent. During FIDC, significant correlations were found between SW & SpO2 and FPA & SpO2. During FIFI, significant correlations were found between RRI & FPA, SW & FPA, HR & SpO2 and FPA & SpO2.Discussion: While there was no significant difference found between HDR activity during FIDC and FIFI, consecutive apnoeas during FIFI triggered a greater magnitude of cardiac activity. Furthermore, significant correlations between RRI and SW with FPA indicate a crosstalk between parasympathetic tone with splenic contraction and increased peripheral sympathetic outflow during FIFI compared to FIDC. In conclusion, HDR activity during consecutive apnoeas does not differ between FIDC and FIFI. There appears to be however a greater level of synchronicity during apnoeas in FIFI compared to FIDC and that this is most likely due to the physiological effects of immersion, which could induce neural recruitment and increased cross talk of HDR pathways.

The Relationship between Stress Levels Measured by a Questionnaire and the Data Obtained by Smart Glasses and Finger Pulse Oximeters among Polish Dental Students

Stress is a physical, mental, or emotional response to a change and is a significant problem in modern society. In addition to questionnaires, levels of stress may be assessed by monitoring physiological signals, such as via photoplethysmogram (PPG), electroencephalogram (EEG), electrocardiogram (ECG), electrodermal activity (EDA), facial expressions, and head and body movements. In our study, we attempted to find the relationship between the perceived stress level and physiological signals, such as heart rate (HR), head movements, and electrooculographic (EOG) signals. The perceived stress level was acquired by self-assessment questionnaires in which the participants marked their stress level before, during, and after performing a task. The heart rate was acquired with a finger pulse oximeter and the head movements (linear acceleration and angular velocity) and electrooculographic signals were recorded with JINS MEME ES_R smart glasses (JINS Holdings, Inc., Tokyo, Japan). We observed significant differences between the perceived stress level, heart rate, the power of linear acceleration, angular velocity, and EOG signals before performing the task and during the task. However, except for HR, these signals were poorly correlated with the perceived stress level acquired during the task.

Acute Effects of the Wim Hof Breathing Method on Repeated Sprint Ability: A Pilot Study

The Wim Hof breathing method (WHBM) combines periods of hyperventilation (HV) followed by voluntary breath-holds (BH) at low lung volume. It has been increasingly adopted by coaches and their athletes to improve performance, but there was no published research on its effects. We determined the feasibility of implementing a single WHBM session before repeated sprinting performance and evaluated any acute ergogenic effects. Fifteen amateur runners performed a single WHBM session prior to a Repeated Ability Sprint Test (RAST) in comparison to voluntary HV or spontaneous breathing (SB) (control) in a randomized cross-over design. Gas exchange, heart rate, and finger pulse oxygen saturation (SpO2) were monitored. Despite large physiological effects in the SpO2 and expired carbon dioxide (VCO2) levels of both HV and WHBM, no significant positive or negative condition effects were found on RAST peak power, average power, or fatigue index. Finger SpO2 dropped to 60 ± 12% at the end of the BHs. Upon the last HV in the WHBM and HV conditions, end-tidal CO2 partial pressure (PETCO2) values were 19 ± 3 and 17 ± 3 mmHg, indicative of respiratory alkalosis with estimated arterial pH increases of +0.171 and of +0.181, respectively. Upon completion of RAST, 8 min cumulated expired carbon dioxide volumes in the WHBM and HV were greater than in SB, suggesting lingering carbon dioxide stores depletion. These findings indicate that despite large physiological effects, a single WHBM session does not improve anaerobic performance in repeated sprinting exercise.

Application Evaluation of High-Flow Humidified Oxygen in Patients with Respiratory Failure after General Anesthesia Extubation for Multiple Injuries

Objective. To explore the effect of high-flow humidified oxygen therapy (HFNC) on patients with respiratory failure after general anesthesia extubation for multiple injuries. Methods. 214 patients with multiple injuries in our hospital who underwent general anesthesia and suffered respiratory failure after weaning extubation and received sequential treatment were included. And, they were divided into control group (HFNC group) and observation group (NIMV group) according to the random number table method. Patients in the control group (125 cases) used high-flow nasal cannula (HFNC) after general anesthesia extubation, while patients in the observation group (89 cases) used NIMV. The respiratory rate, heart rate, finger pulse oxygen, oxygenation index (PaO2/FiO2), and re-tracheal intubation rate in the two groups were compared at 2, 8, and 24 hours after sequential treatment, and the mortality rate and hospital stay of ICU time were whole-course observation. And, the effect of conventional oxygen inhalation or HFNC on oxygenation and prognosis was analyzed. Then, SPSS21.0 software was applied for statistical analysis. To analyze the effect of conventional oxygen inhalation or HFNC on the improvement of oxygenation and prognosis, the receiver operating characteristic (ROC) curve can be used to evaluate the feasibility and treatment effect of high-flow nasal oxygen therapy (HFNC) for patients with respiratory failure after general anesthesia extubation for multiple injuries. Results. Compared with the NIMV group, the respiratory frequency and heart rate of the HFNC group were significantly improved after 2 h, 8 h, and 24 h. At the same time, the finger pulse oxygen and oxygenation index increased significantly and returned to normal levels. HFNC can significantly reduce the reintubation rate, ICU hospital stay, and mortality rate. The area under the ROC curve was 0.9102, with 95% CI (0.8256, 0.9949) and P < 0.0001 . Conclusion. For patients with multiple injuries undergoing general anesthesia and respiratory failure after weaning and extubation, the application of HFNC can moderate patients’ heart rate and respiratory rate faster, increase oxygenation index and finger pulse oxygen, and reduce the reintubation rate, mortality rate, and ICU stay. At the same time, it can effectively improve the respiratory failure of patients after extubation and reduce the occurrence of complications.

Outcome of hypoxic COVID-19 patients treated with dexamethasone-based treatment protocol in a designated COVID center

Background: Managing severe COVID-19 is a difficult situation in resource limited settings. With the inclusion of steroid based treatment guidelines, this can be made feasible in such settings.Methods: This was a hospital record based retrospective cohort study done at a designated COVID hospital. Data of all patients who were 18 years and above, hypoxic and required initiation of dexamethasone-based protocol were analysed. Hypoxia was defined as a finger pulse oximeter value less than 95%. The primary outcome was the percentage of patients who required a referral to the higher centre or died in hospital.Results: 109 patients with hypoxia with a mean age of 55.2±13.5 years and a median symptom duration of 4 days were analyzed. Seventy-eight (71%) patients were male and 81 (74.3%) had other comorbid illnesses. Of the 109 patients, 5 (4.6%) patients died in hospital, 22 (20.2%) patients were referred to higher center for further management and 82 (75.2%) patients could be treated and discharged. Those who were referred or died had lower SpO2, reduced time to initiation of protocol, more severe pneumonia, lower absolute lymphocyte count and lower platelet count. New onset diabetes was detected in 20 (18.3%) patients.Conclusions: Detection of hypoxia early and initiation of dexamethasone-based treatment protocol with timely referral of worsening patients can help to improve outcome in COVID-19 patients. This model can be effectively constructed in limited resource settings and can be of much help to the struggling health infrastructure.

Web-Based Smartphone Algorithm for Calculating Blood Pressure From Photoplethysmography Remotely in a General Adult Population: Validation Study

Background Outside of a clinical setting, oscillometric devices make remote monitoring of blood pressure and virtual care more convenient and feasible. HeartBeat Technologies Ltd developed a novel approach to measuring blood pressure remotely after an initial blood pressure reading by a nurse using the conventional measurement method. Using a finger pulse oximeter, a photoplethysmogram wave is transmitted by Bluetooth to a smartphone or tablet. A smartphone app (MediBeat) transmits the photoplethysmogram to a server for analysis by a proprietary algorithm—the person’s current blood pressure is sent back to the smartphone and to the individual’s health care provider. Objective This study sought to determine whether the HeartBeat algorithm calculates blood pressure as accurately as required by the European Society of Hypertension International Protocol revision 2010 (ESH-IP2) for validation of blood pressure measuring devices. Methods ESH-IP2 requirements, modified to conform to a more recent international consensus statement, were followed. The ESH-IP2 establishes strict guidelines for the conduct and reporting of any validation of any device to measure blood pressure, including using the standard manual blood pressure instrument as a comparator and specific required accuracy levels for low, medium, and high ranges of blood pressure readings. The consensus statement requires a greater number of study participants for each of the blood pressure ranges. The validation of the accuracy of the algorithm was conducted with a Contec CMS50EW pulse oximeter and a Samsung Galaxy XCover 4 smartphone. Results The differences between the HeartBeat-calculated and the manually measured blood pressures of 62 study participants did not meet the ESH-IP2 standards for accuracy for either systolic or diastolic blood pressure measurements. There was no discernible pattern in the inaccuracies of the HeartBeat-calculated measurements. Conclusions The October 4, 2019 version of the HeartBeat algorithm, implemented in combination with the MediBeat app, a pulse oximeter, and an Android smartphone, was not sufficiently accurate for use in a general adult population. Trial Registration ClinicalTrials.gov NCT04082819; http://clinicaltrials.gov/ct2/show/NCT04082819

Protocol for Remote Assessment of Lung Disease and Impact on Physical and Mental Health (RALPMH) (Preprint)

BACKGROUND Chronic Lung disorders like COPD and IPF are characterised by exacerbations which are a significant problem: unpleasant for patients, and sometimes severe enough to cause hospital admission (and therefore NHS pressures) and death. Reducing the impact of exacerbations is very important. Moreover, due to the COVID-19 pandemic, the vulnerable populations with these disorders are at high risk and hence their routine care cannot be done properly. Remote monitoring offers a low cost and safe solution of gaining visibility into the health of people in their daily life. Thus, remote monitoring of patients in their daily lives using mobile and wearable devices could be useful especially in high vulnerability groups. A scenario we consider here is to monitor patients and detect disease exacerbation and progression and investigate the opportunity of detecting exacerbations in real-time with a future goal of real-time intervention. OBJECTIVE The primary objective is to assess the feasibility and acceptability of remote monitoring using wearable and mobile phones in patients with pulmonary diseases. The aims will be evaluated over these areas: Participant acceptability, drop-out rates and interpretation of data, Detection of clinically important events such as exacerbations and disease progression, Quantification of symptoms (physical and mental health), Impact of disease on mood and wellbeing/QoL and The trajectory-tracking of main outcome variables, symptom fluctuations and order. The secondary objective of this study is to provide power calculations for a larger longitudinal follow-up study. METHODS Participants will be recruited from 2 NHS sites in 3 different cohorts - COPD, IPF and Post hospitalised Covid. A total of 60 participants will be recruited, 20 in each cohort. Data collection will be done remotely using the RADAR-Base mHealth platform for different devices - Garmin wearable devices, smart spirometers, mobile app questionnaires, surveys and finger pulse oximeters. Passive data collected includes wearable derived continuous heart rate, SpO2, respiration rate, activity, and sleep. Active data collected includes disease-specific PROMs, mental health questionnaires and symptoms tracking to track disease trajectory in addition to speech sampling, spirometry and finger Pulse Oximetry. Analyses are intended to assess the feasibility of RADAR-Base for lung disorder remote monitoring (include quality of data, a cross-section of passive and active data, data completeness, the usability of the system, acceptability of the system). Where adequate data is collected, we will attempt to explore disease trajectory, patient stratification and identification of acute clinically interesting events such as exacerbations. A key part of this study is understanding the potential of real-time data collection, here we will simulate an intervention using the Exacerbation Rating Scale (ERS) to acquire responses at-time-of-event to assess the performance of a model for exacerbation identification from passive data collected. RESULTS RALPMH study provides a unique opportunity to assess the use of remote monitoring in the study of lung disorders. The study is set to be started in mid-May 2021. The data collection apparatus, questionnaires and wearable integrations have been set up and tested by clinical teams. While waiting for ethics approval, real-time detection models are currently being constructed. CONCLUSIONS RALPMH will provide a reference infrastructure for the use of wearable data for monitoring lung diseases. Specifically information regarding the feasibility and acceptability of remote monitoring and the potential of real-time remote data collection and analysis in the context of chronic lung disorders. Moreover, it provides a unique standpoint to look into the specifics of novel coronavirus without burdensome interventions. It will help plan and inform decisions in any future studies that make use of remote monitoring in the area of Respiratory health. CLINICALTRIAL https://www.isrctn.com/ISRCTN16275601

Clinical study of pulmonary CT lesions and associated bronchiectasis in 115 convalescent patients with novel coronavirus pneumonia (COVID-19) in China

A total of 115 convalescent inpatients with COVID-19 were enrolled. According to the results of scans of lung lesions via computed tomography (CT), the patients were divided into mild, moderate, and severe groups. The clinical data of the patients were collected, including age, gender, finger pulse oxygen pressure, ventricular rate, body temperature, etc. The correlation between the clinical indicators and the lesions of high-resolution CT (HRCT) and bronchiectasis was analyzed. Among the 115 patients, 82 had no bronchiectasis and 33 had bronchiectasis. The bronchodilation-prone layers mainly included the left and right lower lobe of the lung. The probability of branching in the inflamed area was greater than that in the noninflamed area in patients with COVID-19. There were significant differences in gender, CT lesion range, and number of incidents of bronchiectasis between noninflamed and inflamed areas (P < 0.05). Moreover, there were significant differences in age, total proportion of CT lesions, volume of CT lesions, and total number of patients with bronchiectasis among the three groups (P < 0.05). CT lesion range was positively correlated with the total number of patients with bronchiectasis and patient age (respectively, r = 0.186, P < 0.05; r = 0.029, P < 0.05). The lesion range in HRCT images of lungs in patients with COVID-19 is correlated with bronchodilation. The larger the lesion, the higher the probability of bronchiectasis and the more incidents of bronchiectasis.