ГИПОКСИЧЕСКОЕ ПРЕКОНДИЦИОНИРОВАНИЕ СПОСОБСТВУЕТ ПОДДЕРЖАНИЮ КАРДИОРЕСПИРАТОРНЫХ ФУНКЦИЙ КРЫС ПРИ ГЛУБОКОЙ ГИПОТЕРМИИ IN VIVO

Pet-1(-/-) mice with a prenatal, genetically induced loss of 5-hydroxytryptamine (5-HT, serotonin) neurones are compromised in their ability to withstand episodic environmental anoxia via autoresuscitation. Given the prenatal role of 5-HT neurones in the development of neural networks, here we ask if a postnatal loss of 5-HT neurones also compromises autoresuscitation. We treated neonatal rat pups at postnatal day (P)2-3 with an intra-cisternal injection of 5,7-dihydroxytryptamine (5,7-DHT; ~40 μg; n = 8) to pharmacologically lesion the 5-HT system, or vehicle (control; n = 14). At P7-10 we exposed unanaesthetized treated and control pups to 15 episodes of environmental anoxia (97% N(2), 3% CO(2)). Medullary 5-HT content was reduced 80% by 5,7-DHT treatment (P < 0.001). Baseline ventilation (V(E)), metabolic rate (V(O(2))), ventilatory equivalent (V(E)/V(O(2))), heart rate (HR), heart rate variability (HRV) and arterial haemoglobin saturation (S(aO(2))) were no different in 5-HT-deficient pups compared to controls. However, only 25% of 5-HT-deficient pups survived all 15 episodes of environmental anoxia, compared to 79% of control littermates (P = 0.007). High mortality of 5,7-DHT-treated pups was associated with delayed onset of gasping (P < 0.001), delayed recovery of HR from hypoxic-induced bradycardia (P < 0.001), and delayed recovery of eupnoea from hypoxic-induced apnoea (P < 0.001). Treatment with 5,7-DHT affected neither the gasping pattern once initiated, nor HR, V(E)/V(O(2)) or S(aO(2)) during the intervening episodes of room air. A significant increase in HRV occurred in all animals with repeated exposure, and in 5-HT-deficient pups this increase occurred immediately prior to death. We conclude that a postnatal loss of brainstem 5-HT content compromises autoresuscitation in response to environmental anoxia. This report provides new evidence in rat pups that 5-HT neurones serve a physiological role in autoresuscitation. Our data may be relevant to understanding the aetiology of the sudden infant death syndrome (SIDS), in which there is medullary 5-HT deficiency and in some cases evidence of severe hypoxia and failed autoresuscitation.

Recent studies have established that cardiac and respiratory phases can modulate perception and related neural dynamics. While heart rate and respiratory sinus arrhythmia possibly affect interoception biomarkers, such as heartbeat-evoked potentials, the relative changes in heart rate and cardiorespiratory dynamics in interoceptive processes have not yet been investigated. In this study, we investigated the variation in heart and breathing rates, as well as higher functional dynamics including cardiorespiratory correlation and frontal hemodynamics measured with fNIRS, during a heartbeat counting task. To further investigate the functional physiology linked to changes in vagal activity caused by specific breathing rates, we performed the heartbeat counting task together with a controlled breathing rate task. The results demonstrate that focusing on heartbeats decreases breathing and heart rates in comparison, which may be part of the physiological mechanisms related to “listening” to the heart, the focus of attention, and self-awareness. Focusing on heartbeats was also observed to increase frontal connectivity, supporting the role of frontal structures in the neural monitoring of visceral inputs. However, cardiorespiratory correlation is affected by both heartbeats counting and controlled breathing tasks. Based on these results, we concluded that variations in heart and breathing rates are confounding factors in the assessment of interoceptive abilities and relative fluctuations in breathing and heart rates should be considered to be a mode of covariate measurement of interoceptive processes.

Comparison of the heart and breathing rate of acutely ill medical patients recorded by nursing staff with those measured over 5 min by a piezoelectric belt and ECG monitor at the time of admission to hospital

Effects of nooclerin (deanol aceglumate) and slavinorm (vascular polypeptide complex) on the breathing and heart rates were compared in Wistar rats in the course of progressive hypothermia. The animals were immersed in water at 9 ± 0.4 °С. The parameters under study were breathing rate (BR), heart rate (HR), rectal temperature (Тr), esophageal temperature (Tes), and arterial saturation (SpO2). In comparison to controls, at the beginning of hypothermia BR in experimental rats was high at lower Tr values. Nooclerin did not change the trend of HR curve dependence on Tr, whereas slavinorm shifted the trend toward high HR values; besides, it more than doubled life duration before the respiratory arrest. This occurred as a result of rats' transition in the state of cold-hypometabolism when the cardiac activity was maintained by slow breathing. The investigation showed that nooclerin and slavinorm are able to preserve the viability of organisms in hypothermic environment. Both drugs enhance and extend the stage of breathing activation at the beginning of cold immersion in the experimental rats in comparison to their controls. Injection of nooclerin and slavinorm mobilizes the defenses of organism and reduces the pathological effects of deep hypothermia.

Despite the proven efficacy of vagus nerve stimulation (VNS) in seizure control, its precise mechanism of action remains unclear. VNS is known to impact the cardiorespiratory system. In this study, we explored the effects of standard and breathing-synchronized VNS on heart and respiratory rates in anesthetized epileptic rats, as well as their impact on seizure susceptibility. Seizures were induced in rats by intravenous pentylenetetrazol (PTZ) infusion. Three animal groups (n = 4) were subjected to different types of stimulation: Sham VNS, Standard VNS, and Breathing-Synchronized VNS. Measurements included respiration, electrocardiogram, electroencephalogram, and vagal electroneurogram. Each experiment began with a 5-min baseline period, followed by PTZ infusion until tonic-clonic seizure onset, confirmed by video recording and electroencephalogram. Results indicate that the stimulation significantly decreased the heart rate below baseline levels for standard VNS (-120.0 ± 69.1 bpm) and breathing-synchronized VNS (-84.9 ± 61.0 bpm), overcoming the heart rate increasing effect of PTZ infusion observed in the sham VNS (+79.2 ± 35.5 bpm), and there was no recovery during OFF periods. Regarding the breathing rate changes, the sham VNS group presented a slight increase with respect to baseline (+13.6 ± 1.8 bpm). The stimulation slightly increased the average breathing rate for standard VNS (+13.0 ± 14.6 bpm) and breathing-synchronized VNS (+13.7 ± 10.4 bpm), however with significantly enlarged standard deviation. More specifically, the breathing rate presented a pattern that suggests that the rats experienced respiratory hypoxia under stimulation. The VNS modulation of the heart rate and breathing rate in the standard VNS group was similar in the breathing-synchronized VNS, suggesting that the VNS effect is cumulative. Unexpectedly, the sham VNS group required a higher PTZ dose (79.7 ± 13.4 mg/kg) to reach tonic-clonic seizures compared to the standard VNS group (57.9 ± 9.8 mg/kg), and the breathing-synchronized VNS group (60.0 ± 8.7 mg/kg), pointing to an increased seizure susceptibility of VNS in this particular model. Additionally, the latency of the seizures was longer in the sham VNS (291.5 ± 84.4 s) compared to standard VNS (200.5 ± 59.5 s) and breathing-synchronized VNS (206.9 ± 66.0 s), meaning that the seizures under stimulation were starting earlier. A significant linear relationship was found between heart rate and respiratory rate changes, and seizure susceptibility (R 2 = 0.62, p-value = 0.012). We hypothesize that the significant drop in heart rate and the presence of altered respiration patterns, such as apneas or changes in breathing rates, caused by VNS, are related to hypoxia and hypotension conditions, which could increase susceptibility to PTZ. Future investigations with larger sample sizes, incorporating blood pressure and oxygen saturation monitoring, are needed to sort out the role of hypoxia and hypotension as potential covariates affecting the seizure susceptibility caused by overstimulation. Such a finding would support the idea that VNS safety and efficacy require precise adjustments.

ObjectiveApplication of a face mask may provoke the trigeminocardiac reflex, leading to apnoea and bradycardia. This study investigates whether re-application of a face mask in preterm infants at birth alters...

Robust monitoring of vital signs integrated in textile

Objective To observe the effect and safety of the endovascular hypothermia through hypothermic intravenous infusion device in the treatment of patients with severe craniocerebral injury compared with conventional surface cooling. Methods A total of 66 cases of patients with severe cranio-cerebral injury were randomly divided into the observation group and the control group with 33 cases in each group according to envelop randomization. The control group received surface cooling, and the observation group was given surface cooling plus endovascular hypothermia through hypothermic intravenous infusion device. The target temperature was 35 ℃ maintained for 3-5 days, and natural rewarming was applied at the speed of 0.1-0.5 ℃/h to 36.0-37.3 ℃. The time to reach target temperature, the constant stability, the incidence rate and severity of complication such as shiver, arrhythmia, skin injury and agitation were recorded and compared between two groups, as well as the heart rate, breathing rate, pulse rate, blood pressure and Glasgow Coma Scale (GCS) scores after 72 h of treatment. Glasgow Outcome Scale scores 30 days after treatment and nursing workload were also calculated and compared. Results The cooling speed, time to reach target temperature and the ability to maintain at 35 ℃ were (1.3±0.2) ℃/h, (2.3±0.2) h and (6.5±1.8)% in the observation group, respectively, compared with (0.5±0.1) ℃/h, (3.6±0.6) h and (11.3±2.2)% in the control group, which had significant differences (t=1.862, 2.112, 2.408, P < 0.05). The occurrence rates of shiver, arrhythmia, skin damage and dysphoria and restlessness in the observation group were 33.33% (11/33), 9.09% (3/33), 6.06% (2/33) and 27.27% (9/33), respectively, which were much lower than those in the control group 84.85% (28/33), 15.15% (5/33), 33.33% (11/33), 54.55% (18/33), χ2=1.764-2.733, P < 0.05. The heart rate, breathing rate, pulse rate, systolic blood pressure and GCS score after 72 h of treatment were (68.31±3.73) times/min, (16.60±1.52) times/min, (136.35±3.71) mmHg (1 mmHg=0.133 kPa) , (34.61±1.05) ℃, (9.91±4.05) points in the observation group, while (58.31±3.62) times/min, (19.81±1.83) times/min, (150.66±2.70) mmHg, (35.65±1.36) ℃, (7.63±3.17) points in the control group, and there were significant differences between two groups (t=2.275-3.035, P < 0.05) .Besides, the ice-changing ice and turning-over time in the observation group were both remarkably reduced compared with control group, (14.03±3.11) min/h vs (38.12±2.70) min/h (t=3.356, P < 0.05), (15.08±3.07) min/h vs (26.16±2.54) min/h (t=3.021, P < 0.05). Patients with good recovery, mild disability, severe disability, death in the observation group were 16, 13, 3 and 1 case, while 6, 11, 9, 7 cases in the control group (χ2=2.351, P < 0.05). Conclusions The endovascular hypothermia through hypothermic intravenous infusion device can rapidly reduce and effectively maintain target temperature, reduce the incidence rate of complication, improve the vital signs and decrease the nursing workload in order to improve neurological outcome in the treatment of patients with severe craniocerebral injury. Key words: Craniocerebral trauma; Hypothermic intravenous infusion device; Endovascular hypothermia

In this paper the determination of the positions of surface plate electrodes on human trunk for measuring the breathing and heart rate by using the electrical bioimpedance is presented. The designed and implemented measurement device — electrode shirt — is described. The novelty of current work is incorporated into the solution of placing the large surface plate electrodes into the garment. Focus is set on the capacitive connection to the object, revealing the problems of the influence of motions and displacement of the electrodes to the result. The best configurations for heart rate are showing the portion of change of the real part of total body impedance up to 5 percent. The result concerning the breathing rate is showing promising results, reaching up to 90 percent of real part of total body impedance. The best determined electrode placement configurations are showing the possibility of detecting the breathing and heart rate by using single electrode placement.

Objective. High morphological variability magnitude (MVM) and microvolt T wave alternans (TWA) within an electrocardiogram (ECG) signifies increased electrical instability and risk of sudden cardiac death. However, the influence of breathing rate (BR), heart rate (HR), and signal-to-noise ratio (SNR) is unknown and may inflate measured values. Approach. We synthesize ECGs with morphologies derived from the Physikalisch-Technische Bundesanstalt Database. We calculate MVM and TWA at varying BRs, HRs and SNRs. We compare the MVM and TWA of signal with versus without breathing at varying HRs and SNRs. We then quantify the percentage of MVM and TWA estimates affected by BR and HR in a healthy population and assess the effect of removing these affected estimates on a method for classifying individuals with and without post-traumatic stress disorder (PTSD). Main results. For signals with high SNR (>15 dB), MVM is significantly increased when BRs are > 9 respirations/minute (rpm) and HRs are < 100 beats/minute (bpm). Increased TWAs are detected for HR/BR pairs of 60/15, 60/30 and 120/30 bpm/rpm. For 18 healthy participants, 8.33% of TWA windows and 66.76% of MVM windows are affected by BR and HR. On average, the number of windows with TWA elevations > 47 μV decreases by 23% after excluding regions with significant BR and HR effect. Adding HR and BR to a morphological variability feature increases the classification performance by 6% for individuals with and without PTSD. Significance. Physiological BR and HR significantly increase MVM and TWA , indicating that BR and HR should be considered separately as confounders. The code for this work has been released as part of an open-source toolbox.

Some smartphones have the capability to process video streams from both the front- and rear-facing cameras simultaneously. This paper proposes a new monitoring method for simultaneous estimation of heart and breathing rates using dual cameras of a smartphone. The proposed approach estimates heart rates using a rear-facing camera, while at the same time breathing rates are estimated using a non-contact front-facing camera. For heart rate estimation, a simple application protocol is used to analyze the varying color signals of a fingertip placed in contact with the rear camera. The breathing rate is estimated from non-contact video recordings from both chest and abdominal motions. Reference breathing rates were measured by a respiration belt placed around the chest and abdomen of a subject; reference heart rates (HR) were determined using the standard electrocardiogram. An automated selection of either the chest or abdominal video signal was determined by choosing the signal with a greater autocorrelation value. The breathing rate was then determined by selecting the dominant peak in the power spectrum. To evaluate the performance of the proposed methods, data were collected from 11 healthy subjects. The breathing ranges spanned both low and high frequencies (6–60 breaths/min), and the results show that the average median errors from the reflectance imaging on the chest and the abdominal walls based on choosing the maximum spectral peak were 1.43% and 1.62%, respectively. Similarly, HR estimates were also found to be accurate.

Studies on five groups of rats (six animals per group) addressed changes in neurons in hippocampal fields CA1 and CA4 seven days after severe hypobaric hypoxia (180 mmHg, 3 h) using different numbers (1, 3, or 6) of sessions of preconditioning (PC) with moderate hypobaric hypoxia (360 mmHg, 2 h, 24 h before severe hypoxia). Single-session PC was found not to prevent damage to neuron structure with neuron death by day 7 after severe hypoxia. At the same time, six and especially three sessions of PC induced protective mechanisms preventing neuron damage. Use of six sessions of PC, in contrast to three, resulted in moderate chromatolysis in hippocampal neurons, which may be a consequence of prolonged hypermetabolic activity of neurons and may be evidence of their functional overloading.

The Sleep Number smart bed uses embedded ballistocardiography, together with network connectivity, signal processing, and machine learning, to detect heart rate (HR), breathing rate (BR), and sleep vs. wake states. This study evaluated the performance of the smart bed relative to polysomnography (PSG) in estimating epoch-by-epoch HR, BR, sleep vs. wake, mean overnight HR and BR, and summary sleep variables. Forty-five participants (aged 22–64 years; 55% women) slept one night on the smart bed with standard PSG. Smart bed data were compared to PSG by Bland–Altman analysis and Pearson correlation for epoch-by-epoch HR and epoch-by-epoch BR. Agreement in sleep vs. wake classification was quantified using Cohen’s kappa, ROC analysis, sensitivity, specificity, accuracy, and precision. Epoch-by-epoch HR and BR were highly correlated with PSG (HR: r = 0.81, |bias| = 0.23 beats/min; BR: r = 0.71, |bias| = 0.08 breaths/min), as were estimations of mean overnight HR and BR (HR: r = 0.94, |bias| = 0.15 beats/min; BR: r = 0.96, |bias| = 0.09 breaths/min). Calculated agreement for sleep vs. wake detection included kappa (prevalence and bias-adjusted) = 0.74 ± 0.11, AUC = 0.86, sensitivity = 0.94 ± 0.05, specificity = 0.48 ± 0.18, accuracy = 0.86 ± 0.11, and precision = 0.90 ± 0.06. For all-night summary variables, agreement was moderate to strong. Overall, the findings suggest that the Sleep Number smart bed may provide reliable metrics to unobtrusively characterize human sleep under real life-conditions.

The retrotrapezoid nucleus (RTN), located in the parafacial region, contains glutamatergic neurons that express the transcriptor factor Phox2b and that are suggested to be central respiratory chemoreceptors. Studies in anaesthetized animals or in vitro have suggested that RTN neurons are important in the control of breathing by influencing respiratory rate, inspiratory amplitude and active expiration. However, the contribution of these neurons to cardiorespiratory control in conscious rats is not clear. Male Holtzman rats (280-300 g, n = 6-8) with bilateral stainless-steel cannulae implanted into the RTN were used. In conscious rats, the microinjection of the ionotropic glutamatergic agonist NMDA (5 pmol in 50 nl) into the RTN increased respiratory frequency (by 42%), tidal volume (by 21%), ventilation (by 68%), peak expiratory flow (by 24%) and mean arterial pressure (MAP, increased by 16 ± 4, versus saline, 3 ± 2 mmHg). Bilateral inhibition of the RTN neurons with the GABA(A) agonist muscimol (100 pmol in 50 nl) reduced resting ventilation (52 ± 34, versus saline, 250 ± 56 ml min(-1) kg(-1) with absolute values) and attenuated the respiratory response to hypercapnia and hypoxia. Muscimol injected into the RTN slightly reduced resting MAP (decreased by 13 ± 7, versus saline, increased by 3 ± 2 mmHg), without changing the effects of hypercapnia or hypoxia on MAP and heart rate. The results suggest that RTN neurons activate facilitatory mechanisms important to the control of ventilation in resting, hypoxic or hypercapnic conditions in conscious rats.

Monitoring cardiovascular and respiratory measurements corresponds to the precision livestock farming (PLF) objective to continuously monitor and assess dairy cows' welfare and health. Changes in heart rate, breathing rate, and oxygen saturation (SpO2) are valuable metrics in human and veterinary medicine to assess stress, pain, illness, and detect critical conditions. The common way to measure heart rate is either manually or with a stethoscope. Under research conditions, heart rate is usually measured with a sports watch chest belt. Breathing rate is obtained by counting the cow's flank movements which is a time-consuming and labor-intensive method that requires training and is prone to human error. No devices are available on the market that enable practical and easy pulse oximetry in farm animals. This study presents a wireless nose ring sensor system (NoRS) composed of thermal and photoplothysmography sensors that attach to the nostrils of four Holstein dairy cows. The NoRS's thermocouple measured the cow's nasal cavity air temperature; an optic sensor measured the IR (660 nm) and RED (660 nm) signals reflected from the cow's nasal septum. Breathing was calculated from the thermocouple signal's center frequency with a fast Fourier transformation or the signal peak count (i.e., oscillations). The breathing rate was compared to breathing observed by concurrently counting the flank movements. Heart rate and SpO2 were measured by integrated pulse oximetry and heart rate monitor module (MAX30101 TinyCircuit) assembled on the NoRS circuit. Heart rate was also measured with FFT and by counting the number of peaks from the optic sensor's raw IR and RED signals. These measures were compared to an off-the-shelf hand-held pulse oximeter's heart rate and SpO2 readings during the same time. The comparisons revealed highly significant correlations for the heart rate readings where the strength of the correlation was sensitive to the method. The correlation between breathing rate and the veterinarian's visual observations was low, albeit significant. Thus, inhale-exhale cycle counting constitutes a more precise approach than flank movement counts. The hand-held device's 96% SpO2 is compatible with near-saturation values expected in healthy cows. The mean NoRS SpO2 reading was 3% less. After further piloting under field conditions, the NoRS will require no animal restraining to automatically and continuously record cows' breathing rate, heart rate, and SpO2.