The "Abdominal Circulatory Pump": An Auxiliary Heart during Exercise?

Apart from its role as a flow generator for ventilation the diaphragm has a circulatory role. The cyclical abdominal pressure variations from its contractions cause swings in venous return from the splanchnic venous circulation. During exercise the action of the abdominal muscles may enhance this circulatory function of the diaphragm. Eleven healthy subjects (25 ± 7 year, 70 ± 11 kg, 1.78 ± 0.1 m, 3 F) performed plantar flexion exercise at ~4 METs. Changes in body volume (ΔVb) and trunk volume (ΔVtr) were measured simultaneously by double body plethysmography. Volume of blood shifts between trunk and extremities (Vbs) was determined non-invasively as ΔVtr-ΔVb. Three types of breathing were studied: spontaneous (SE), rib cage (RCE, voluntary emphasized inspiratory rib cage breathing), and abdominal (ABE, voluntary active abdominal expiration breathing). During SE and RCE blood was displaced from the extremities into the trunk (on average 0.16 ± 0.33 L and 0.48 ± 0.55 L, p < 0.05 SE vs. RCE), while during ABE it was displaced from the trunk to the extremities (0.22 ± 0.20 L p < 0.001, p < 0.05 RCE and SE vs. ABE respectively). At baseline, Vbs swings (maximum to minimum amplitude) were bimodal and averaged 0.13 ± 0.08 L. During exercise, Vbs swings consistently increased (0.42 ± 0.34 L, 0.40 ± 0.26 L, 0.46 ± 0.21 L, for SE, RCE and ABE respectively, all p < 0.01 vs. baseline). It follows that during leg exercise significant bi-directional blood shifting occurs between the trunk and the extremities. The dynamics and partitioning of these blood shifts strongly depend on the relative predominance of the action of the diaphragm, the rib cage and the abdominal muscles. Depending on the partitioning between respiratory muscles for the act of breathing, the distribution of blood between trunk and extremities can vary by up to 1 L. We conclude that during exercise the abdominal muscles and the diaphragm might play a role of an "auxiliary heart.

Spontaneous breathing pattern as respiratory functional outcome in children with spinal muscular atrophy (SMA)

Introduction: SMA is characterised by progressive motor and respiratory muscle weakness. We aimed to verify if in SMA children 1)each form is characterized by specific ventilatory and thoracoabdominal pattern(VTAp) during quiet breathing(QB); 2)VTAp is affected by salbutamol therapy, currently suggested as standard treatment, or by the natural history(NH) of SMA; 3)the severity of global motor impairment linearly correlates with VTAp. Materials and methods: VTAp was analysed on 32 SMA type I (SMA1, the most severe form), 51 type II (SMA2, the moderate), 8 type III (SMA3, the mildest) and 20 healthy (HC) using opto-electronic plethysmography. Spirometry, cough and motor function were measured in a subgroup of patients. Results: In SMA1, a normal ventilation is obtained in supine position by rapid and shallow breathing with paradoxical ribcage motion. In SMA2, ventilation is within a normal range in seated position due to an increased respiratory rate(p0.05) while tachypnea occurred in type I NH. A linear correlation(p<0.001) was found between motor function scales and VTAp. Conclusion: A negative or reduced %ΔVRC,P, indicative of ribcage muscle weakness, is a distinctive feature of SMA1 and SMA2 since infancy. Its quantitative assessment represents a non-invasive, non-volitional index that can be obtained in all children, even uncollaborative, and provides useful information on the action of ribcage muscles that are known to be affected by the disease. Low values of motor function scales indicate impairment of motor but also of respiratory function

Efficacy of lung volume optimization maneuver monitored by optoelectronic pletismography in the management of congenital diaphragmatic hernia

Newborns affected by congenital diaphragmatic hernia (CDH) need cardio-respiratory stabilization before undergoing surgical repair. Open lung strategy is a well-established approach to optimize lung volume in preterm infants with Respiratory Distress Syndrome (RDS), using both High Frequency Oscillatory Ventilation (HFOV) and Conventional Mechanical Ventilation (CMV). We report a case of left CDH with severe lung hypoplasia, managed applying open lung strategy in HFOV (pre-surgery period) and in Assist-Control with Volume Guarantee (post-surgery period), guided by SpO2changes, TcPO2and TcPCO2monitoring. Opto-electronic plethysmography was used to measure end-expiratory chest wall volume changes (ΔEEcw) related to lung volume variations occurring during pressure changes. OEP confirmed the efficacy of using SpO2and transcutaneous gas monitoring during this recruitment maneuver

Incidents and injuries in foot launched flying extreme sports: a snap shot from the UK

Background. Participation rates in extreme sports have grown exponentially in the last 40 years,often surpassing traditional sporting activities. The purpose of this study was to examine injury rates in foot launched flying sports, i.e. sports in which a pilot foot-launches into flight with a wing already deployed. Method. This paper is based on a retrospective analysis of the reports of incidents that occurred between 2000 and 2014 among the British Hang Gliding and Paragliding Association members. Results. The majority of the 1411 reported injuries were in the lower limb, followed by the upper limb. The most common lower limb injury was to the ankle and included fractures sprains and dislocations. The distribution of injures was different in each discipline. The calculated yearly fatality rate (fatalities /100,000 participants) was 40.4 in hang gliding, 47.1 in paragliding, 61.9 in powered hang gliding and 83.4 in powered paragliding; the overall value for foot launched flight sports was 43.9. Discussion. Significant differences in injury rates and injury patterns were found among different sport disciplines that can be useful to steer research on safety, and adopt specific safety rules about flying, protective clothing and safety systems in each of these sports

The effect of posture on asynchronous chest wall movement in COPD

Priori R, Aliverti A, Albuquerque AL, Quaranta M, Albert P, Calverley PM. the effect of posture on asynchronous chest wall movement in COPD. J Appl Physiol 114: 1066-1075, 2013. First published February 14, 2013; doi:10.1152/japplphysiol.00414.2012.-Chronic obstructive pulmonary disease (COPD) patients often show asynchronous movement of the lower rib cage during spontaneous quiet breathing and exercise. We speculated that varying body position from seated to supine would influence rib cage asynchrony by changing the configuration of the respiratory muscles. Twenty-three severe COPD patients (forced expiratory volume in 1 s = 32.5 +/- 7.0% predicted) and 12 healthy age-matched controls were studied. Measurements of the phase shift between upper and lower rib cage and between upper rib cage and abdomen were performed with opto-electronic plethysmography during quiet breathing in the seated and supine position. Changes in diaphragm zone of apposition were measured by ultrasounds. Control subjects showed no compartmental asynchronous movement, whether seated or supine. in 13 COPD patients, rib cage asynchrony was noticed in the seated posture. This asynchrony disappeared in the supine posture. in COPD, upper rib cage and abdomen were synchronous when seated, but a strong asynchrony was found in supine. the relationships between changes in diaphragm zone of apposition and volume variations of chest wall compartments supported these findings. Rib cage paradox was noticed in approximately one-half of the COPD patients while seated, but was not related to impaired diaphragm motion. in the supine posture, the rib cage paradox disappeared, suggesting that, in this posture, diaphragm mechanics improves. in conclusion, changing body position induces important differences in the chest wall behavior in COPD patients.Politecn Milan, Dipartimento Elettron Informaz & Bioingn, I-20133 Milan, ItalyUniversidade Federal de São Paulo, Dept Med, São Paulo, BrazilUniv Liverpool, Univ Hosp Aintree, Ctr Clin Sci, Liverpool L69 3BX, Merseyside, EnglandUniversidade Federal de São Paulo, Dept Med, São Paulo, BrazilWeb of Scienc

Paradoxical movement of the lower ribcage at rest and during exercise in COPD patients

Paradoxical inward displacement of the costal margin during inspiration is observed in many chronic obstructive pulmonary disease patients at rest but its importance is unclear.The current authors studied 20 patients (forced expiratory volume in one second 32.6 +/- 11.7, functional residual capacity 186 +/- 32% predicted) and 10 healthy controls at rest and during symptom-limited incremental exercise. With optoelectronic plethysmography, the phase shift between pulmonary and abdominal ribcage volumes and the percentage of inspiratory time the ribcage compartments moved in opposite directions were quantified, using control data to define the normal range of movement.Eight patients showed lower ribcage inspiratory paradox at rest (P+), while 12 patients did not (P-). This was unrelated to resting lung function or exercise tolerance. Total end-expiratory chest wall volume (EEVcw) increased immediately when exercise began in P+ patients, but later in exercise in P- patients. This difference in EEVcw was mainly due to a greater increase of end-expiratory pulmonary ribcage volume in P+ patients. During exercise, dyspnoea increased similarly in the two groups, while leg effort increased more markedly in the patients without paradox.In conclusion, lower ribcage paradox at rest is reproducible and associated with early-onset hyperinflation of the chest wall and predominant dyspnoea at end-exercise. When paradox is absent, the sense of leg effort becomes a more important symptom limiting exercise.British Lung FoundationEuropean Respiratory Society (ERS)ERS COEDPolitecn Milan, TBM Lab, Dipartimento Bioingn, I-20133 Milan, ItalyUniv Liverpool, Ctr Clin Sci, Univ Hosp Aintree, Liverpool L69 3BX, Merseyside, EnglandUniversidade Federal de São Paulo, São Paulo, BrazilUniversidade Federal de São Paulo, São Paulo, BrazilEuropean Respiratory Society (ERS): 69Web of Scienc

Detrended fluctuation analysis of day and night breathing parameters from a wearable respiratory holter

Background and objective: This study focuses on the application of Detrended Fluctuation Analysis (DFA) to understand the variability and correlation properties of respiratory parameters time series obtained by means of a wearable. Methods: Data from 18 healthy volunteers collected using the AirgoTM band, which provides signals proportional to thoracic circumference at a sampling frequency of 10 Hz. The primary aim was to provide preliminary normative data for DFA scaling factors. Results: DFA was applied to 6-h recordings, revealing significant differences (p &lt; 0.001) in scaling factors (α values) for tidal volume (night: 0.97 [0.09], day: 0.88 [0.04]), minute ventilation (night: 1.02 [0.10], day: 0.91 [0.07), mean inspiratory flow (night: 0.98 [0.06], day: 0.88 [0.06]), mean expiratory flow (night: 0.89 [0.08], day: 0.81 [0.06]), and duty cycle (night: 0.64 [0.04], day: 0.59 [0.03]). Quadratic detrending highlighted additional differences not captured with linear detrending, particularly in inspiratory and expiratory time. These findings suggest distinct regulatory patterns during sleep. Conclusions: DFA analysis of respiratory parameters obtained from wearable devices reveals distinct regulatory patterns between day and night conditions, particularly in parameters related to tidal volume and ventilation. These findings demonstrate the potential of DFA to uncover physiological differences in respiratory control mechanisms, especially during sleep, despite technical limitations such as the strong dependency of DFA scaling factors on sampling frequency, duration, and detrending order. Future research should address the limitations of sample size and expand normative datasets to include individuals with respiratory conditions, to translate this methodology into specific clinical applications

Performance Assessment for the Validation of Wireless Communication Engines in an Innovative Wearable Monitoring Platform †

In today’s health-monitoring applications, there is a growing demand for wireless and wearable acquisition platforms capable of simultaneously gathering multiple bio-signals from multiple body areas. These systems require well-structured software architectures, both to keep different wireless sensing nodes synchronized each other and to flush collected data towards an external gateway. This paper presents a quantitative analysis aimed at validating both the wireless synchronization task (implemented with a custom protocol) and the data transmission task (implemented with the BLE protocol) in a prototype wearable monitoring platform. We evaluated seven frequencies for exchanging synchronization packets (10 Hz, 20 Hz, 30 Hz, 40 Hz, 50 Hz, 60 Hz, 70 Hz) as well as two different BLE configurations (with and without the implementation of a dynamic adaptation of the BLE Connection Interval parameter). Additionally, we tested BLE data transmission performance in five different use case scenarios. As a result, we achieved the optimal performance in the synchronization task (1.18 ticks as median synchronization delay with a Min-Max range of 1.60 ticks and an Interquartile range (IQR) of 0.42 ticks) when exploiting a synchronization frequency of 40 Hz and the dynamic adaptation of the Connection Interval. Moreover, BLE data transmission proved to be significantly more efficient with shorter distances between the communicating nodes, growing worse by 30.5% beyond 8 m. In summary, this study suggests the best-performing network configurations to enhance the synchronization task of the prototype platform under analysis, as well as quantitative details on the best placement of data collectors

An IMU-Based Wearable System for Respiratory Rate Estimation in Static and Dynamic Conditions

Purpose: Breathing parameters change with activity and posture, but currently available solutions can perform measurements only during static conditions. Methods: This article presents an innovative wearable sensor system constituted by three inertial measurement units to simultaneously estimate respiratory rate (RR) in static and dynamic conditions and perform human activity recognition (HAR) with the same sensing principle. Two units are aimed at detecting chest wall breathing-related movements (one on the thorax, one on the abdomen); the third is on the lower back. All units compute the quaternions describing the subject’s movement and send data continuously with the ANT transmission protocol to an app. The 20 healthy subjects involved in the research (9 men, 11 women) were between 23 and 54&nbsp;years old, with mean age 26.8, mean height 172.5&nbsp;cm and mean weight 66.9&nbsp;kg. Data from these subjects during different postures or activities were collected and analyzed to extract RR. Results: Statistically significant differences between dynamic activities (“walking slow”, “walking fast”, “running” and “cycling”) and static postures were detected (p &lt; 0.05), confirming the obtained measurements are in line with physiology even during dynamic activities. Data from the reference unit only and from all three units were used as inputs to artificial intelligence methods for HAR. When the data from the reference unit were used, the Gated Recurrent Unit was the best performing method (97% accuracy). With three units, a 1D Convolutional Neural Network was the best performing (99% accuracy). Conclusion: Overall, the proposed solution shows it is possible to perform simultaneous HAR and RR measurements in static and dynamic conditions with the same sensor system