Cardiorespiratory Variables Research Articles

No Difference In Heart Rate Recovery During Graded Treadmill Testing In Patients With And Without Nonalcoholic Fatty Liver Disease (NAFLD)

Cardiac Mortality is the most common cause of death for nonalcoholic fatty liver disease (NAFLD), which is linked to physical inactivity and obesity. PURPOSE: To determine whether individuals with NAFLD show heart rate recovery impairment (iHRR is≤12 beats per minute at 1 minute post-exercise, an independent predictor of mortality) compared to non-NAFLD participants following graded treadmill testing (GTT) to volitional exhaustion. METHODS: Non-pharmacological clinical research participants with and without NAFLD were included. All performed symptom-limited, Modified Bruce GTT. Gas exchange captured cardiorespiratory variables and impedance cardiometry assessed heart rate, stroke volume, and cardiac output (CO) continuously during rest, testing, and recovery. Participants completed nutrition, activity, and fatigue questionnaires. Linear regression assessed effects of covariates on HRR. RESULTS: 86 participants (48.8% Male, 62.8% Caucasian, 65.8% NAFLD/NASH, Age 48 ± 13.6 years) were included for analysis. T-test comparisons showed individuals with NAFLD to be older (52 vs 41.4 years, p=.001), have higher body mass index (31.2 vs 28.4 kg/m 2 , p=.007), and increased body fat percentage, (34.1% vs 28.6%, p=.006) but showed no differences for resting pulse, blood pressure, gender, or ethnicity. Per GTT, individuals with NAFLD had reduced oxygen consumption at anaerobic threshold (AT) (12.3 vs 15.6 mL/kg/min) and peak exertion (23.1 vs 31.2 mL/kg/min, p<.001) compared to non-NAFLD. The NAFLD cohort also reported reduced maximal and average activity scores compared to the non-NAFLD group (MAS 89.8 vs 81.4, p=.001; AAS 88.1 vs 77.6, p<.001). No group differences were found for iHRR presence or continuous HRR measure. Stepwise linear regression showed peak CO (B=0.317, p=.041) and MAS (B=.348, p=.025) to be significant predictors of HRR for all participants (R 2 =.261). CONCLUSIONS: No HRR post exercise differences were found between NAFLD and non-NAFLD individuals. Increased CO and self-reported exercise capacity may indicate lower probability of impaired HRR. AAS and MAS were reduced in the NAFLD group, which may reflect reduced aerobic capacity at peak performance and AT. NAFLD individuals may benefit from exercise participation encouragement to improve tolerance of physical activity.

Cardiorespiratory hysteresis during incremental high-altitude ascent-descent quantifies the magnitude of ventilatory acclimatization.

What is the central question of this study? We assessed the utility of a new metric for quantifying ventilatory acclimatization to high altitude, derived from differential ascent and descent steady-state cardiorespiratory variables (i.e. hysteresis). Furthermore, we aimed to investigate whether the magnitude of cardiorespiratory hysteresis was associated with the development of acute mountain sickness. What is the main finding and its importance? Hysteresis in steady-state cardiorespiratory variables quantifies ventilatory acclimatization to high altitude. The magnitude of cardiorespiratory hysteresis during ascent to and descent from high altitude was significantly related to the development of symptoms of acute mountain sickness. Hysteresis in steady-state chemoreflex drive can provide a simple, non-invasive method of tracking ventilatory acclimatization to high altitude. Maintenance of arterial blood gases is achieved through sophisticated regulation of ventilation, mediated by central and peripheral chemoreflexes. Respiratory chemoreflexes are important during exposure to high altitude owing to the competing influence of hypoxia and hypoxic hyperventilation-mediated hypocapnia on steady-state ventilatory drive. Inter-individual variability exists in ventilatory acclimatization to high altitude, potentially affecting the development of acute mountain sickness (AMS). We aimed to quantify ventilatory acclimatization to high altitude by comparing differential ascent and descent values (i.e. hysteresis) in steady-state cardiorespiratory variables. We hypothesized that: (i)the hysteresis area formed by cardiorespiratory variables during ascent and descent would quantify the magnitude of ventilatory acclimatization; and (ii)larger hysteresis areas would be associated with lower AMS symptom scores during ascent. In 25 healthy, acetazolamide-free trekkers ascending to and descending from 5160m, cardiorespiratory hysteresis was measured in the partial pressure of end-tidal CO2 , peripheral oxygen saturation, minute ventilation, chemoreceptor stimulus index (end-tidal CO2 /peripheral oxygen saturation) and the calculated steady-state chemoreflex drive (SS-CD; minute ventilation/chemoreceptor stimulus index) using portable devices (capnograph, peripheral pulse oximeter and respirometer, respectively). Symptoms of AMS were assessed daily using the Lake Louise questionnaire. We found that: (i)ascent-descent hysteresis was present in all cardiorespiratory variables; (ii)SS-CD is a valid metric for tracking ventilatory acclimatization to high altitude; and (iii)the highest AMS scores during ascent exhibited a significant, moderate and inverse correlation with the magnitude of SS-CD hysteresis (rs =-0.408, P=0.043). We propose that ascent-descent hysteresis is a new and feasible way to quantify ventilatory acclimatization in trekkers during high-altitude exposure.

No physiological or biomechanical sex-by-load interactions during treadmill-based load carriage

This study investigated whether physiological demand or gait mechanics differ between sexes during treadmill load carriage. Female (n = 15) and male (n = 15) military recruit-type participants with no load carriage experience completed three 10-minute walking trials at a self-selected speed with increasing relative body-borne loads (0%, 20%, and 40% body weight). A range of cardiorespiratory, perceptual and biomechanical variables were measured. Self-selected walking speed was similar between sexes (4.6–4.8 km·h−1, p > .05) and there were no significant sex-by-load interactions for any variables. Absolute O2 and CO2 were greater in males (difference 175–178 mL·min−1, p < .001), however, when relative to body mass, O2 was similar between sexes (p > .05). Across all loads, cadence was 7 ± 2 steps·min−1 faster (p = .004) and stance time was 0.06 ± 0.02 s shorter (p = .013) in females. Increasing load resulted in greater physiological demand, cadence, % stance time, and step length (p < .05). Practitioner summary: Literature comparing physiological and biomechanical variables between sexes during load carriage is scarce. Physiological and biomechanical sex differences were limited to relative measures associated with physical size (height and mass). Future research may pool male and female participants when conducting trials up to ten minutes in length. Abbreviations: BW: body weight; COM: centre of mass; HR: heart rate; HRmax: maximum heart rate; RER: respiratory exchange ratio; RPE: rating of perceived exertion; VCO2: volume of carbon dioxide; VE: ventilation; VO2: volume of oxygen; VO2max: maximum volume of oxygen

Six-Hour Manual Ventilation with a Bag-Valve-Tube Device by Briefly Trained Non-Medical Personnel is Feasible.

Manual ventilation with a bag-valve device (BVD) is a Basic Life Support skill. Prolonged manual ventilation may be required in resource-poor locations and in severe disasters such as hurricanes, pandemics, and chemical events. In such circumstances, trained operators may not be available and lay persons may need to be quickly trained to do the job. The current study investigated whether minimally trained operators were able to manually ventilate a simulated endotracheally intubated patient for six hours. Two groups of 10 volunteers, previously unfamiliar with manual ventilation, received brief, structured BVD-tube ventilation training and performed six hours of manual ventilation on an electronic lung simulator. Operator cardiorespiratory variables and perceived effort, as well as the quality of the delivered ventilation, were recorded. Group One ventilated a "normal lung" (compliance 50cmH2O/L, resistance 5cmH2O/L/min). Group Two ventilated a "moderately injured lung" (compliance 20cmH2O/L, resistance 20cmH2O/L/min). Volunteers' blood pressure, heart rate (HR), respiratory rate (RR), and peripheral capillary oxygen saturation (SpO2) were stable throughout the study. Perceived effort was minimal. The two groups provided clinically adequate and similar RRs (13.3 [SD = 3.0] and 14.1 [SD = 2.5] breaths/minute, respectively) and minute volume (MV; 7.6 [SD = 2.1] and 7.7 [SD = 1.4] L/minute, respectively). The results indicate that minimally trained persons can effectively perform six hours of manual BVD-tube ventilation of normal and moderately injured lungs, without undue effort. Quality of delivered ventilation was clinically adequate.

1209 Effect Of Wearables On Sleep In Healthy Individuals: A Randomized Cross-over Trial And Validation Study

Abstract Introduction To determine whether a wearable sleep-tracker improves perceived sleep quality in healthy subjects. To test whether wearables reliably measure sleep quantity and quality compared to polysomnography. Methods A single-center randomized cross-over trial of community-based participants without medical conditions or sleep disorders. Wearable device (WHOOP, Inc.) that provided feedback regarding sleep information to the participant for 1-week and maintaining sleep logs versus 1-week of maintaining sleep logs alone. Self-reported daily sleep behaviors were documented in sleep logs. Polysomnography was performed on one night when wearing the wearable. PROMIS Sleep disturbance sleep scale was measured at baseline, 7, and 14 days of study participation. Results In 32 participants (21 women; 23.8 + 5 years), wearables improved nighttime sleep quality (PROMIS sleep disturbance; B= -1.69; 95% Confidence Interval -3.11, -0.27; P=0.021) after adjusting for age, sex, baseline, and order effect. There was a small increase in self-reported daytime naps when wearing the device (B = 3.2; SE 1.4; P=0.023) but total daily sleep remained unchanged (P=0.43). The wearable had low bias (2.5 minutes) and low precision (5.6 minutes) errors for measuring sleep duration and measured dream sleep and slow wave sleep accurately (Intra-class coefficient 0.74 + 0.28 and 0.85 + 0.15, respectively). Bias and precision error for heart rate (bias -0.17%; precision 1.5%) and respiratory rate (bias 1.8%’ precision 6.7%) were very low when compared to that measured by electrocardiogram and inductance plethysmography during polysomnography. Conclusion In healthy people, wearables can improve sleep quality and accurately measure sleep and cardiorespiratory variables. Support WHOOP Inc.

Modifying a Full-Face Snorkel Mask to Meet N95 Respirator Standards for Use With Coronavirus Disease 2019 Patients.

We evaluated a full-face snorkel mask with an airway circuit filter to protect health care providers against airborne pathogens. First, a quantified N95 fit test was performed using aerosolized saline. Second, cardiorespiratory variables (heart rate, peripheral oxygen saturation, end-tidal carbon dioxide tension, and inspired fraction of carbon dioxide) were measured at rest and during moderate exercise. The modified mask passed the United States Occupational Safety and Health Administration (OSHA) N95 respirator (N95) fit test requirements with a fit factor of 142. Neither hypercapnia nor hypoxemia occurred. This modified mask has the potential to protect providers who care for patients with coronavirus disease 2019 (COVID-19).

Dietary supplementation with New Zealand blackcurrant extract enhances fat oxidation during submaximal exercise in the heat

ObjectivesThis study investigated the effect of 7 days’ supplementation with New Zealand blackcurrant extract on thermoregulation and substrate metabolism during running in the heat. DesignRandomized, double-blind, cross-over study. MethodsTwelve men and six women (mean±SD: Age 27±6 years, height 1.76±0.10m, mass 74±12kg, V̇O2max 53.4±7.0mLkg−1min−1) completed one assessment of maximal aerobic capacity and one familiarisation trial (18°C, 40% relative humidity, RH), before ingesting 2×300mgday−1 capsules of CurraNZ™ (each containing 105mg anthocyanin) or a visually matched placebo (2×300mg microcrystalline cellulose M102) for 7 days (washout 14 days). On day 7 of each supplementation period, participants completed 60min of fasted running at 65% V̇O2max in hot ambient conditions (34°C and 40% relative humidity). ResultsCarbohydrate oxidation was decreased in the NZBC trial [by 0.24gmin−1 (95% CI: 0.21–0.27gmin-1)] compared to placebo (p= 0.014, d=0.46), and fat oxidation was increased in the NZBC trial [by 0.12gmin−1 (95% CI: 0.10 to 0.15gmin−1)], compared to placebo (p=0.008, d=0.57). NZBC did not influence heart rate (p=0.963), rectal temperature (p=0.380), skin temperature (p=0.955), body temperature (p=0.214) or physiological strain index (p=0.705) during exercise. ConclusionsSeven-days intake of 600mg NZBC extract increased fat oxidation without influencing cardiorespiratory or thermoregulatory variables during prolonged moderate intensity running in hot conditions.

Titration of sevoflurane anesthesia to optimize the time to regain airway reflexes in patients undergoing elective surgery: A randomized clinical trial comparing desflurane and sevoflurane anesthesia

Desflurane has adverse environmental effects, but has clinical advantages to speed emergence and return of protective airway reflexes compared with sevoflurane. We hypothesized that weaning of the inspired sevoflurane during the final 15minutes of surgery would eliminate differences in airway reflex recovery between these agents. After obtaining IRB approval and informed consent, 40 patients undergoing elective surgery (≥1-hour) randomly received desflurane or sevoflurane. Patients swallowed 20mL of water without drooling or coughing, and then received sedation and PONV pre-medication. Anesthesia was induced using propofol and fentanyl and maintained with desflurane or sevoflurane through a laryngeal mask airway maintaining a bispectral index of 45-50 and 50-60 during the final 15minutes before surgery end. Cardiorespiratory variables and age-adjusted minimal alveolar concentration were recorded. The duration between anesthetic discontinuation and first appropriate response to command was measured; the laryngeal mask airway was removed. Two minutes after responding to command, patients were positioned semi-upright and attempted to swallow water. If successful swallowing was not achieved, the test was repeated every 4minutes after each failure until successful swallowing was achieved. Average anesthetic concentration and bispectral index was similar in patients receiving desflurane vs sevoflurane. Response times after discontinuation of anesthetics were similar. There were no differences in the recovery of swallowing ability between desflurane and sevoflurane groups. Weaning of sevoflurane during the final 15 minutes of surgery eliminates clinical advantages of the more rapid return of airway reflexes with desflurane.

Use of portable gas analyzers during pediatric field testing.

To compare performance and cardiorespiratory responses in field tests performed by healthy children, with and without the use of a portable gas analyzer (PGA), and to analyze the reproducibility of the tests. The study included healthy children aged 6 to 14 years old. The sample was divided into children who underwent field tests (modified shuttle walk test [MSWT], 6-minute walk test [6MWT], and ADL-Glittre for pediatrics [TGlittre-P]) without PGA (GS) and children who carried the equipment K4b2 -COSMED, Rome, Italy (GK). A total of 120 children participated in the study, 31 in the GK (mean age 10.16 ± 1.81 years old) and 89 in GS (mean age 10.1 ± 1.79 years old). The groups did not differ from each other and there was no significant difference in the performance of the 6MWT and MSWT intergroup(P > .05), but the significant alteration in the variables of the cardiorespiratory response was identified. In the TGlittre-P, the GK completed the test in a shorter time than the GS (2.69 ± 0.38 minutes vs 2.91 ± 0.40 minutes) and both presented alterations in most cardiorespiratory variables. The intragroup reproducibility showed concordance in all tests, and there was no concordance between groups (P > .05). The use of PGA had a lower time spent on TGlittre-P. In the 6MWT and MSWT, there was no difference in cardiorespiratory performance and response with and without the use of PGA. The three field tests were reproducible, but the same test, with and without the use of PGA, did not show agreement.

Prostaglandin E1 in infants with congenital diaphragmatic hernia (CDH) and life-threatening pulmonary hypertension

BackgroundSuprasystemic pulmonary hypertension (PH) is highly predictive of pulmonary morbidity and death in infants with congenital diaphragmatic hernia (CDH). ObjectivesTo report the effects and tolerability of Prostaglandin E1 (PGE1) in newborns with severe CDH and life-threatening PH. MethodsNewborn infants with isolated CDH and life-threatening PH defined by an acute worsening of the cardiorespiratory function, and bidirectional or exclusive right-to-left shunting across the ductus arteriosus (DA) with an acceleration of the blood flow >1.5 m.s−1 assessed by Doppler echocardiography. Serial measurements of cardiorespiratory variables have been recorded before and after PGE1. Results18 infants (out of 102 in the cohort) were included in the study (gestational age: 39 ± 2 weeks). The median FiO2, and preductal and postductal SpO2 were 80% [50; 100], 91% [88; 95] and 86% [82; 91], respectively, before treatment. FiO2 decreased to 35% [30–40] (p = 0.001) at H6. Maximal blood flow velocities in the DA decreased after starting PGE1 from 2.2 m.s−1 [1.5–2.5] to 1 m.s−1 [0.55–1.2] (p < 0.001). ConclusionsPGE1 treatment improved oxygenation and circulatory function in newborn infants with severe CDH and life-threatening PH. Our data provide evidence that restrictive DA may result in suprasystemic pulmonary hypertension in CDH infants, and that PGE1 may improve cardiorespiratory failure through reopening of the DA. Type of studyTreatment study. Level of evidenceLevel III.

Effect of Hand Held Vibrating Tools on Nerve Conduction Study in Dental Residents.

Repetitive exposure to vibration has been shown to induce peripheral nerve dysfunction. Dentists are exposed to handheld vibrating tools in their daily clinical practice. Most of the studies are done in dentists who have symptoms such as paresthesia and numbness of the hands. Thus, we conducted the study to explore the effect of vibration on nerve conduction variables in apparently healthy asymptomatic dental residents. This cross-sectional study enrolled 22 dental residents and age matched 22 medical residents as controls. Nerve conduction study was performed in median and ulnar nerves of both hands. Anthropometric and cardiorespiratory variables were comparable between the groups. There were no statistically significant differences between dental and medical residents in the sensory conduction variables (right median onset latency=2.05±0.27 vs 1.91±0.21, p value=0.07; right median amplitude =27.80±8.11 vs 29.55±7.04, p=0.45; right median conduction velocity = 59.54±7.05 vs 61.06±5.15, p= 0.42) and motor conduction variables (right median distal latency = 2.87±0.38 vs 2.87±0.38, p= 0.94; right median distal amplitude=10.71±2.19 vs 11.10±2.37, p=0.58; right median conduction velocity= 70.57±13.16 vs 68.53±7.73, p= 0.54) of median and ulnar nerves. Further, there was no significant difference between the dominant and non-dominant hands of dental residents. Hand held vibration tools did not alter nerve conduction study parameters of dental residents.

Cardiorespiratory Response during the 1-min Sit-to-Stand Test in Chronic Obstructive Pulmonary Disease.

This study aimed to assess the cardiorespiratory response during a 1-min sit-to-stand test (1STS) in comparison with cycling cardiopulmonary exercise test (CPET) in people with chronic obstructive pulmonary disease (COPD) and in healthy subjects and to evaluate whether 1STS may induce leg fatigue in these individuals. Fourteen people with severe COPD and 12 healthy subjects performed a 1STS and a CPET during which cardiorespiratory response, perception of dyspnea, and leg fatigue were assessed. Quadriceps strength was assessed before and after 1STS, and contractile fatigue was defined as a postexercise fall in quadriceps twitch force greater than 15% of resting values. In COPD, peak V˙O2, V˙E, and HR achieved during 1STS reached 113%, 103%, and 93% of the corresponding values during CPET, respectively. Decrease in SpO2 from preexercise to peak exercise and the magnitude of dynamic hyperinflation were similar between 1STS and CPET. Borg dyspnea and leg fatigue scores were higher for CPET than 1STS. In healthy subjects, peak cardiorespiratory demand and symptom scores were higher during CPET compared with 1STS. A V˙O2 overshoot during recovery was observed only in people with COPD. After 1STS, the V˙O2 half-time recovery of COPD was 152 ± 25 s compared with 74 ± 18 in healthy subjects (P < 0.01). Ten people with COPD and five healthy subjects were considered as fatiguers. The 1STS induced a similar cardiorespiratory stress to that of CPET and was associated with contractile quadriceps fatigue in people with severe COPD. The V˙O2 overshoot and slower recovery time of cardiorespiratory variables seen in COPD demonstrate the clinical relevance of monitoring the recovery phase of exercise.

Effects of pneumoperitoneum and trendelenburg position on intraocular pressure (IOP) in isofluorane anesthetised cats

The aim of this study was to determine whether a pneumoperitoneum of 10 mmHg combined or not with the Trendelenburg position could lead to significant changes in intraocular pressure (IOP), ocular pressure perfusion (OPP), and cardiorespiratory variables; as well as determine whether a correlation exists between IOP and mean arterial blood pressure (MAP), and/or partial pressure of carbon dioxide in arterial blood (PaCO2) in cats. Animals were allocated in two groups (n=7/group): GC (without inclination) and GTREN (Trendelenburg position). The variables were recorded before (baseline) and during 30 minutes (T5-T30) after insufflation. In GTREN, a reduction in heart rate was observed at T5 and in respiratory rate at T5 and T15. There was an increase in IOP at T5-T30 in comparison to baseline. There was a reduction in potential of hydrogen in arterial blood in both groups at all times in comparison to baseline. Partial pressure of carbon dioxide in arterial blood was increased at T15-T30 in GC and at T5-T30 in GTREN. In conclusion, the pneumoperitoneum of 10mmHg CO2 did not significantly affect IOP or OPP in cats anaesthetised with isofluorane and kept under spontaneous ventilation. However, induced pneumoperitoneum combined with Trendelenburg position resulted in an increase in IOP in cats subjected to the same anaesthetic conditions, but did not affect OPP.

Cooper Test Provides Better Half-Marathon Performance Prediction in Recreational Runners Than Laboratory Tests.

This study compared the ability to predict performance in half-marathon races through physiological variables obtained in a laboratory test and performance variables obtained in the Cooper field test. Twenty-three participants (age: 41.6 ± 7.6 years, weight: 70.4 ± 8.1 kg, and height: 172.5 ± 6.3 cm) underwent body composition assessment and performed a maximum incremental graded exercise laboratory test to evaluate maximum aerobic power and associated cardiorespiratory and metabolic variables. Cooper’s original protocol was performed on an athletic track and the variables recorded were covered distance, rating of perceived exertion, and maximum heart rate. The week following the Cooper test, all participants completed a half-marathon race at the maximum possible speed. The associations between the laboratory and field tests and the final time of the test were used to select the predictive variables included in a stepwise multiple regression analysis, which used the race time in the half marathon as the dependent variable and the laboratory variables or field tests as independent variables. Subsequently, a concordance analysis was carried out between the estimated and actual times through the Bland-Altman procedure. Significant correlations were found between the time in the half marathon and the distance in the Cooper test (r = −0.93; p < 0.001), body weight (r = 0.40; p < 0.04), velocity at ventilatory threshold 1, (r = −0.72; p < 0.0001), speed reached at maximum oxygen consumption (vVO2max), (r = −0.84; p < 0.0001), oxygen consumption at ventilatory threshold 2 (VO2VT2) (r = −0.79; p < 0.0001), and VO2max (r = −0.64; p < 0.05). The distance covered in the Cooper test was the best predictor of time in the half-marathon, and might predicted by the equation: Race time (min) = 201.26 – 0.03433 (Cooper test in m) (R2 = 0.873, SEE: 3.78 min). In the laboratory model, vVO2max, and body weight presented an R2 = 0.77, SEE 5.28 min. predicted by equation: Race time (min) = 156.7177 – 4.7194 (vVO2max) – 0.3435 (Weight). Concordance analysis showed no differences between the times predicted in the models the and actual times. The data indicated a high predictive power of half marathon race time both from the distance in the Cooper test and vVO2max in the laboratory. However, the variable associated with the Cooper test had better predictive ability than the treadmill test variables. Finally, it is important to note that these data may only be extrapolated to recreational male runners.

Efectos cardiopulmonares y ácido-base de la infusión continua de fentanilo, ketamina y lidocaína en pacientes caninos ASA I

The combination of fentanyl, lidocaine, and ketamine (FLK) has been widely used in canine surgery as part of the analgesic protocol. Some effects associated with its application have been described by the literature. The objective was to evaluate the cardiopulmonary effects produced by the infusion of FLK and the use of isoflurane during surgery in canine ASA I patients. Samples was taken of nine healthy female dogs of different breeds, ages, and sizes undergoing ovariohysterectomy that received a continuous infusion of FLK (0,08, 30, and 15 μg/kg/min, respectively) as part of the analgesic protocol. The results of cardiac and respiratory rates, non-invasive blood pressure monitoring, cardiac output and index, arterial oxygen saturation, end-tidal carbon dioxide, body temperature, arterial partial pressure of carbon dioxide and oxygen, bicarbonate, blood pH, total carbon dioxide, and blood lactate were measured before (time 1; T1) and during (time 2; T2) the surgery. Body temperature and acid base status at T1 and T2 were statistically different (p&lt;0,05). In contrast, there was no difference between the effects of the analgesic protocol on cardiorespiratory and hemodynamic variables at T1 and T2. The results found indicate that changes in pH and temperature were due to additional factors different conditions outside the FLK infusion. Although cardiovascular and hemodynamic variables were not found as significant, it was possible to observe an improving on tissue perfusion and hemodynamic stability.

Synchronization of Autonomic and Cerebral Rhythms During Listening to Music: Effects of Tempo and Cognition of Songs.

A large number of studies document cardiorespiratory changes occurring while listening to music. Less is known, however, about the interaction between cardiorespiratory and cerebral electrical rhythms during listening to music and how cognition and acoustic structural aspects of songs influence that interaction. We focused on tempo as a structural feature of songs, since tempo is a major determinant of physiological responses to music, and on familiarity and randomization of phase of local spectra of known and unknown songs for cognition. Our results indicated an overall increase in the degree of synchronization among cardiorespiratory variables (Heart rate (RR), systolic and diastolic blood pressure (SBP, DBP), respiration) and between cardiorespiratory and cerebral (EEG) oscillations during all songs. We also observed a marked decrease in respiratory frequency bandwidth and increase in respiratory rate while listening to songs, and slow song produced the most periodic breathing. Compared with slow tempo, during fast song, DBP and cerebral oscillations became less synchronized with high frequency components of RR suggesting that the processes causing the previously known reduction in vagal activity with increase in tempo also may have caused the decrease in these synchronizations. Cognition of songs affected the SBP coherencies the most. DBP was synchronized with respiration more than all other measured variables in response to auditory stimuli. Results indicate an overall increase in the degree of synchronization among a variety of cerebral electrical and autonomically driven cardiovascular rhythms. It is possible that this significant increase in synchronizations underlies the widely reported pleasurable and palliative effects of listening to music.

Cardiorespiratory and thermal responses to hypercapnia in chickens exposed to CO2 during embryonic development

The concentration of CO2 in the environment surrounding the embryo impacts development and may also influence the cardiorespiratory responses after hatching. Therefore, we aimed to evaluate the cardiorespiratory and thermal responses to hypercapnia in chicks that were exposed to CO2 during embryonic development, i.e., incubation. Embryos were incubated without and with a gradual increase in CO2 concentration up to 1 % during the first ten days of incubation. Ten-day-old chicks (males and females) were again acutely exposed to hypercapnia (7 % CO2), or to room air (normocapnia) and pulmonary ventilation, arterial pH and blood gases, arterial blood pressure and heart rate, body temperature (Tb) and oxygen consumption (V⋅O2) were measured. Compared to control animals, male chicks incubated with 1 % CO2 presented an attenuated ventilatory response to hypercapnia (P < 0.05), whereas no difference was found in the hypercapnic ventilatory response in both female chick groups (0 % vs 1 % CO2 incubation). Hypercapnia induced bradycardia in all groups (P < 0.001). The CO2 exposure during incubation did not alter the cardiovascular responses to hypercapnia in post-hatch animals. There were no significant effects of incubation treatment (0 % vs 1 % CO2) or sex in the mean arterial pressure, Tb, and V⋅O2 of animals in normocapnia and hypercapnia. As for the V⋅E/V⋅O2, hypercapnia caused an increase in both groups (P < 0.05), regardless of incubation treatment. In conclusion, among cardiorespiratory and metabolic variables, the ventilatory response to hypercapnia can be attenuated by pre-exposure to 1 % CO2 during embryonic development, especially in male chicks up to 10 days.

Episodic stimulation of central chemoreceptor neurons elicits disordered breathing and autonomic dysfunction in volume overload heart failure.

Enhanced central chemoreflex (CC) gain is observed in volume overload heart failure (HF) and is correlated with autonomic dysfunction and breathing disorders. The aim of this study was to determine the role of the CC in the development of respiratory and autonomic dysfunction in HF. Volume overload was surgically created to induce HF in male Sprague-Dawley rats. Radiotelemetry transmitters were implanted for continuous monitoring of blood pressure and heart rate. After recovering from surgery, conscious unrestrained rats were exposed to episodic hypercapnic stimulation [EHS; 10 cycles/5 min, inspiratory fraction of carbon dioxide () 7%] in a whole body plethysmograph for recording of cardiorespiratory function. To determine the contribution of CC to cardiorespiratory variables, selective ablation of chemoreceptor neurons within the retrotrapezoid nucleus (RTN) was performed via injection of saporin toxin conjugated to substance P (SSP-SAP). Vehicle-treated rats (HF+Veh and Sham+Veh) were used as controls for SSP-SAP experiments. Sixty minutes post-EHS, minute ventilation was depressed in sham animals relative to HF animals (ΔV̇e: −5.55 ± 2.10 vs. 1.24 ± 1.35 mL/min 100 g, P < 0.05; Sham+Veh vs. HF+Veh). Furthermore, EHS resulted in autonomic imbalance, cardiorespiratory entrainment, and ventilatory disturbances in HF+Veh but not Sham+Veh rats, and these effects were significantly attenuated by SSP-SAP treatment. Also, the apnea-hypopnea index (AHI) was significantly lower in HF+SSP-SAP rats compared with HF+Veh rats (AHI: 5.5 ± 0.8 vs. 14.4 ± 1.3 events/h, HF+SSP-SAP vs. HF+Veh, respectively, P < 0.05). Finally, EHS-induced respiratory-cardiovascular coupling in HF rats depends on RTN chemoreceptor neurons because it was reduced by SSP-SAP treatment. Overall, EHS triggers ventilatory plasticity and elicits cardiorespiratory abnormalities in HF that are largely dependent on RTN chemoreceptor neurons.

Hydrogen Rich Water Improved Ventilatory, Perceptual and Lactate Responses to Exercise.

The potential anti-fatigue and performance benefits of hydrogen rich water (HRW) have resulted in increased research interest over the past 5 years. The aim of this study was to assess physiological and perceptual responses to an incremental exercise protocol after administration of 600 ml HRW within 30 min before exercise. This randomized, double blinded placebo-controlled cross over study included twelve healthy males aged 27.1±4.9 years. The exercise protocol consisted of a 10 min warm-up at 1.0 W.kg-1, followed by 8 min at 2.0, 3.0, and 4.0 W.kg-1, respectively. Cardio-respiratory variables, lactate and ratings of perceived exertion (RPE) were assessed in the last minute of each step. A significantly lower blood lactate was found with HRW (4.0±1.6 and 8.9±2.2 mmol.l-1) compared to Placebo (5.1±1.9 and 10.6±3.0 mmol.l-1) at 3.0, and 4.0 W.kg-1, respectively. Ventilatory equivalent for oxygen and RPE exhibited significantly lower values with HRW (32.3±7.2, and 17.8±1.2 points, respectively) compared to Placebo (35.0±8.4, and 18.5±0.8 points, respectively) at 4 W.kg-1. To conclude, acute pre-exercise supplementation with HRW reduced blood lactate at higher exercise intensities, improved exercise-induced perception of effort, and ventilatory efficiency.

ADRB2 GLN27GLU POLYMORPHISM ASSOCIATED WITH ADIPOSITY INDICATORS AND IL-10 IN ADOLESCENTS

ABSTRACT Introduction: Studies of association between obesity and genetic factors have demonstrated a significant contribution of polymorphisms related to body fat distribution and subclinical inflammatory process. Objective: To investigate the association between genotypes of the Gln27Glu polymorphism of the ADRB2 gene and indicators of adiposity, inflammatory markers, metabolic parameters and parameters of physical fitness in overweight adolescents. Methods: A total of 44 male and female adolescents, aged between 13 and 17 years, with positive clinical diagnosis of overweight, were divided into two groups according to the Gln27Glu polymorphism genotypes of the ADRB2 gene: a) Group of carriers of the 27Glu allele (Gln27Glu/Glu27Glu) (n = 22); b) Group of non-carriers of the 27Glu allele (Gln27Gln) (n = 22). Both groups were evaluated for body composition, sexual maturation, cardiorespiratory fitness variables and indicators of muscle strength. Basal glycemia and insulin, lipid profile and inflammatory profile were measured. Abdominal subcutaneous and visceral adiposities were evaluated by ultrasonography. Genotyping of the Gln27Glu polymorphism of the ADRB2 gene was performed by the Taqman allelic discrimination assay. Results: The genotype frequency found was: Gln/Gln (n = 22) (50.0%), Gln/Glu (n = 18) (41.0%) and Glu/Glu (n = 4) %). The frequency of the 27Glu allele was 29.5%. The group of adolescent carriers of the 27Glu allele of the ADRB2 gene presented higher mean adiposity indicators (abdominal circumference, trunk fat mass and visceral fat), as well as lower IL-10 concentrations when compared to non-carriers. Conclusions: The 27Glu allele was associated with adiposity indicators in overweight adolescents, while subcutaneous abdominal fat exhibited an inverse relationship with inflammatory variables and maximum oxygen uptake, which may result in more damage to health. Level of evidence III; Case-control study.