The Role of Chest Compressions on Ventilation during Advanced Cardiopulmonary Resuscitation

There is growing interest in the quality of manual ventilation during cardiopulmonary resuscitation (CPR), but accurate assessment of ventilation parameters remains a challenge. Waveform capnography is currently the reference for monitoring ventilation rate in intubated patients, but fails to provide information on tidal volumes and inspiration–expiration timing. Moreover, the capnogram is often distorted when chest compressions (CCs) are performed during ventilation compromising its reliability during CPR. Our main purpose was to characterize manual ventilation during CPR and to assess how CCs may impact on ventilation quality. Methods: Retrospective analysis were performed of CPR recordings fromtwo databases of adult patients in cardiac arrest including capnogram, compression depth, and airway flow, pressure and volume signals. Using automated signal processing techniques followed by manual revision, individual ventilations were identified and ventilation parameters were measured. Oscillations on the capnogram plateau during CCs were characterized, and its correlation with compression depth and airway volume was assessed. Finally, we identified events of reversed airflow caused by CCs and their effect on volume and capnogram waveform. Results: Ventilation rates were higher than the recommended 10 breaths/min in 66.7% of the cases. Variability in ventilation rates correlated with the variability in tidal volumes and other ventilatory parameters. Oscillations caused by CCs on capnograms were of high amplitude (median above 74%) and were associated with low pseudo-volumes (median 26 mL). Correlation between the amplitude of those oscillations with either the CCs depth or the generated passive volumes was low, with correlation coefficients of −0.24 and 0.40, respectively. During inspiration and expiration, reversed airflow events caused opposed movement of gases in 80% of ventilations. Conclusions: Our study confirmed lack of adherence between measured ventilation rates and the guideline recommendations, and a substantial dispersion in manual ventilation parameters during CPR. Oscillations on the capnogram plateau caused by CCs did not correlate with compression depth or associated small tidal volumes. CCs caused reversed flow during inspiration, expiration and in the interval between ventilations, sufficient to generate volume changes and causing oscillations on capnogram. Further research is warranted to assess the impact of these findings on ventilation quality during CPR.This research was funded by the grant PID2021-126021OB-I00 by MCIN/AEI/10.13039/501100011033 and by ERDF A way of making Europe, and by the grant IT1590-22 by the Basque Government. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Wearable technology: role in respiratory health and disease

In the future, diagnostic devices will be able to monitor a patient's physiological or biochemical parameters continuously, under natural physiological conditions and in any environment through wearable biomedical sensors. Together with apps that capture and interpret data, and integrated enterprise and cloud data repositories, the networks of wearable devices and body area networks will constitute the healthcare's Internet of Things. In this review, four main areas of interest for respiratory healthcare are described: pulse oximetry, pulmonary ventilation, activity tracking and air quality assessment. Although several issues still need to be solved, smart wearable technologies will provide unique opportunities for the future or personalised respiratory medicine

Continuous Monitoring of Vital Signs With Wearable Sensors During Daily Life Activities:Validation Study

BACKGROUND: Continuous telemonitoring of vital signs in a clinical or home setting may lead to improved knowledge of patients’ baseline vital signs and earlier detection of patient deterioration, and it may also facilitate the migration of care toward home. Little is known about the performance of available wearable sensors, especially during daily life activities, although accurate technology is critical for clinical decision-making. OBJECTIVE: The aim of this study is to assess the data availability, accuracy, and concurrent validity of vital sign data measured with wearable sensors in volunteers during various daily life activities in a simulated free-living environment. METHODS: Volunteers were equipped with 4 wearable sensors (Everion placed on the left and right arms, VitalPatch, and Fitbit Charge 3) and 2 reference devices (Oxycon Mobile and iButton) to obtain continuous measurements of heart rate (HR), respiratory rate (RR), oxygen saturation (SpO(2)), and temperature. Participants performed standardized activities, including resting, walking, metronome breathing, chores, stationary cycling, and recovery afterward. Data availability was measured as the percentage of missing data. Accuracy was evaluated by the median absolute percentage error (MAPE) and concurrent validity using the Bland-Altman plot with mean difference and 95% limits of agreement (LoA). RESULTS: A total of 20 volunteers (median age 64 years, range 20-74 years) were included. Data availability was high for all vital signs measured by VitalPatch and for HR and temperature measured by Everion. Data availability for HR was the lowest for Fitbit (4807/13,680, 35.14% missing data points). For SpO(2) measured by Everion, median percentages of missing data of up to 100% were noted. The overall accuracy of HR was high for all wearable sensors, except during walking. For RR, an overall MAPE of 8.6% was noted for VitalPatch and that of 18.9% for Everion, with a higher MAPE noted during physical activity (up to 27.1%) for both sensors. The accuracy of temperature was high for VitalPatch (MAPE up to 1.7%), and it decreased for Everion (MAPE from 6.3% to 9%). Bland-Altman analyses showed small mean differences of VitalPatch for HR (0.1 beats/min [bpm]), RR (−0.1 breaths/min), and temperature (0.5 °C). Everion and Fitbit underestimated HR up to 5.3 (LoA of −39.0 to 28.3) bpm and 11.4 (LoA of −53.8 to 30.9) bpm, respectively. Everion had a small mean difference with large LoA (−10.8 to 10.4 breaths/min) for RR, underestimated SpO(2) (>1%), and overestimated temperature up to 2.9 °C. CONCLUSIONS: Data availability, accuracy, and concurrent validity of the studied wearable sensors varied and differed according to activity. In this study, the accuracy of all sensors decreased with physical activity. Of the tested sensors, VitalPatch was found to be the most accurate and valid for vital signs monitoring

Maternal Hemodynamic Effects of Medical Gases and Uterotonics in Obstetrics

Aim of study: To elucidate the hemodynamic effects of pharmaceutical and medical interventions during pregnancy and childbirth on the mother.Introduction: Oxytocin, oxygen, and nitrous oxide are pharmaceuticals very commonly used in labor and delivery. These pharmaceuticals have known cardiovascular adverse effects. Some of these effects might be detrimental for the mother in case of major blood loss or preexisting cardiovascular disease, but the full extent of these effects is not known. The newer uterotonic carbetocin may have another adverse effect profile.Study population: Pregnant women during elective cesarean section; first trimester pregnant women during scheduled surgery for suction curettage; and pregnant and nonpregnant women during the third trimester.Methods: Cardiovascular effects are measured through ECG, blood pressure, oxygen saturation, and photoplethysmographic pulse wave analysis. By measuring the light absorption of infrared light through the finger, a waveform is obtained, from which it is possible to calculate indices of vascular stiffness and cardiac performance.Results: Oxytocin and carbetocin both have similar effects of vasodilation and blood pressure decrease. Pregnant women experienced more profound subjective side effects from nitrous oxide inhalations than nonpregnant controls. Oxygen alone and in a mix with nitrous oxide have vasoconstrictive and possible negative inotropic effects. These effects were more profound in pregnant women than in nonpregnant controls.Conclusion: The abovementioned medical interventions have cardiovascular effects that are sometimes quite profound. These effects can be shown with a simple and pain-free methodology. Carbetocin seems to have similar cardiovascular adverse effects compared to Oxytocin. Prudence should be taken when administering these drugs to compromised mothers. Both nitrous oxide and oxygen have vasoconstrictive and possible negative inotropic effects that were more prominent in pregnant women than in nonpregnant controls. Some of the effects seen from nitrous oxide might be due to the oxygen fraction in the gas mixture. Awareness of cardiovascular effects is important when treatment of the mother with oxytocin receptor agonists as well as with nitrous oxide and oxygen is considered. Oxygen treatment should not be used without a precise indication

Sensors for Vital Signs Monitoring

Sensor technology for monitoring vital signs is an important topic for various service applications, such as entertainment and personalization platforms and Internet of Things (IoT) systems, as well as traditional medical purposes, such as disease indication judgments and predictions. Vital signs for monitoring include respiration and heart rates, body temperature, blood pressure, oxygen saturation, electrocardiogram, blood glucose concentration, brain waves, etc. Gait and walking length can also be regarded as vital signs because they can indirectly indicate human activity and status. Sensing technologies include contact sensors such as electrocardiogram (ECG), electroencephalogram (EEG), photoplethysmogram (PPG), non-contact sensors such as ballistocardiography (BCG), and invasive/non-invasive sensors for diagnoses of variations in blood characteristics or body fluids. Radar, vision, and infrared sensors can also be useful technologies for detecting vital signs from the movement of humans or organs. Signal processing, extraction, and analysis techniques are important in industrial applications along with hardware implementation techniques. Battery management and wireless power transmission technologies, the design and optimization of low-power circuits, and systems for continuous monitoring and data collection/transmission should also be considered with sensor technologies. In addition, machine-learning-based diagnostic technology can be used for extracting meaningful information from continuous monitoring data

Machine learning and signal processing contributions to identify circulation states during out-of-hospital cardiac arrest

212 p. (eusk) 216 p. (eng.)Bat-bateko bihotz geldialdia (BBG) ustekabeko bihotz jardueraren etenaldi gisa definitzen da [9], non odol perfusioa ez baita iristenez burmuinera, ez beste ezinbesteko organoetara. BBGa ahalik eta azkarren tratatu behar da berpizte terapien bidez bat-bateko bihotz heriotza (BBH) ekiditeko [10, 11]. Ohikoena BBGa ospitalez kanpoko inguruneetan gertatzea da [12] eta kasu gehienetan ez da lekukorik egoten [13]. Horregatik, berpizte terapien aplikazio goiztiarra erronka mediku eta soziala da gaur egun

Characterization and processing of novel neck photoplethysmography signals for cardiorespiratory monitoring

Epilepsy is a neurological disorder causing serious brain seizures that severely affect the patients' quality of life. Sudden unexpected death in epilepsy (SUDEP), for which no evident decease reason is found after post-mortem examination, is a common cause of mortality. The mechanisms leading to SUDEP are uncertain, but, centrally mediated apneic respiratory dysfunction, inducing dangerous hypoxemia, plays a key role. Continuous physiological monitoring appears as the only reliable solution for SUDEP prevention. However, current seizure-detection systems do not show enough sensitivity and present a high number of intolerable false alarms. A wearable system capable of measuring several physiological signals from the same body location, could efficiently overcome these limitations. In this framework, a neck wearable apnea detection device (WADD), sensing airflow through tracheal sounds, was designed. Despite the promising performance, it is still necessary to integrate an oximeter sensor into the system, to measure oxygen saturation in blood (SpO2) from neck photoplethysmography (PPG) signals, and hence, support the apnea detection decision. The neck is a novel PPG measurement site that has not yet been thoroughly explored, due to numerous challenges. This research work aims to characterize neck PPG signals, in order to fully exploit this alternative pulse oximetry location, for precise cardiorespiratory biomarkers monitoring. In this thesis, neck PPG signals were recorded, for the first time in literature, in a series of experiments under different artifacts and respiratory conditions. Morphological and spectral characteristics were analyzed in order to identify potential singularities of the signals. The most common neck PPG artifacts critically corrupting the signal quality, and other breathing states of interest, were thoroughly characterized in terms of the most discriminative features. An algorithm was further developed to differentiate artifacts from clean PPG signals. Both, the proposed characterization and classification model can be useful tools for researchers to denoise neck PPG signals and exploit them in a variety of clinical contexts. In addition to that, it was demonstrated that the neck also offered the possibility, unlike other body parts, to extract the Jugular Venous Pulse (JVP) non-invasively. Overall, the thesis showed how the neck could be an optimum location for multi-modal monitoring in the context of diseases affecting respiration, since it not only allows the sensing of airflow related signals, but also, the breathing frequency component of the PPG appeared more prominent than in the standard finger location. In this context, this property enabled the extraction of relevant features to develop a promising algorithm for apnea detection in near-real time. These findings could be of great importance for SUDEP prevention, facilitating the investigation of the mechanisms and risk factors associated to it, and ultimately reduce epilepsy mortality.Open Acces

The utility of handheld and wearable devices in the diagnosis of cardiac arrhythmias

The aim of this thesis is to highlight the existing body of literature on the utility of wearable and handheld devices in the diagnosis and management of cardiac arrhythmias. Furthermore, the thesis investigates the accuracy and utility of the AliveCor Kardia for the detection of cardiac arrhythmias in a systematic fashion

Investigation of splanchnic perfusion utilising an intraluminal opto-electronic sensor placed in the duodenum

The splanchnic region (abdominal gastrointestinal organs) is sometimes known as the “canary of the body” for its susceptibility to develop hypoxia at an earlier stage, analogue to the old times practice in coal mining. When the neuroendocrine response is activated, it exhibits regulation of blood flow and extraction of oxygen, facilitating redistribution of blood to vital organs. This can ultimately lead to systemic inflammatory response and multiple organ failure. The vital need to monitor the perfusion of the splanchnic region in critically ill patients has not yet been met by existing techniques. The goal of this research was to evaluate the feasibility of using the technique of photoplethysmography intraluminally in the duodenum in order to measure the haemodynamic changes occurring in the splanchnic circulation in a minimally invasive fashion. A bespoke processing system and data acquisition virtual instrument were designed and developed to allow continuous and simultaneous monitoring of two probes: an existing miniaturised PPG probe intended for intraluminal use and optically- identical finger PPG probe. Nine anaesthetised patients undergoing elective open laparotomy surgery were recruited and consented for the clinical trial at The Royal London Hospital. Due to the great proximity to the surgical site, monitoring of duodenal pulse oximetry signals could not be done in a continuous way. Also, the presence of moderate respiratory modulation in otherwise good quality, high amplitude signals seemed to result in an underestimation of arterial blood saturation of 2%. A frequency domain algorithm was thus applied to the data with results in agreement with both the finger PPG probe and commercial pulse oximeter. Blood oxygen saturation estimation at respiratory frequency yielded values within the physiological range expected for venous blood. For three of the patients, PPG signals were also acquired from the stomach, with results showing a similar pattern to the ones obtained from the duodenum. During the clinical trials, two patients experienced hypotension. PPG signals obtained before, during and after showed a great decrease in estimated blood oxygen saturations, which remained low even when monitored haemodynamical variables were back to normal values. Finger PPG probe estimations and commercial pulse oximetry values did not demonstrate this change. This suggests the possibility of photoplethysmography identifying changes in tissue oxygenation and blood volume in the splanchnic circulation resulting from external and/or internal regulatory mechanisms. This clinical trial thus show the great promise of pulse oximetry as complementary monitoring for patients at risk of developing splanchnic ischaemia