Impact Of Body Position Research Articles

Impact of head-down-tilt body position on abdomen resistance for urinary bladder monitory applications

Tissue electrical impedance (or bioimpedance) is a quantity related to the passive, frequency-dependent electrical properties of a biological tissue and is a promising modality for continuous monitoring of relative bladder volume and bladder activity. In this study, the impact of body position [specifically 6° head-down tilt (HDT)] intended to induce fluid redistribution and, therefore, result in a change in the electrical resistance of the abdomen is evaluated. The abdomen resistance (10 kHz–100 kHz) of nine healthy young adults was measured before and after 240 min in a 6° HDT position. Over this period, the resistance increase was not statistically significant even though the average bladder volume increased by 506 mL. It was expected that the abdomen resistance would decrease with an increase in bladder volume over this period. The masking of the expected resistance decrease is attributed to the shift in the fluid from the legs/abdomen to the neck/chest caused by the HDT body position over this period. Overall, this suggests that methods to differentiate bladder volume changes from other types of fluid shifts in the body are needed for resistance-based monitoring under free-living conditions.

Impact of body position on hemodynamic measurements during exercise: A tale of two bikes.

The addition of exercise testing during right heart catheterization (RHC) is often required to accurately diagnose causes of exercise intolerance like early pulmonary vascular disease, occult left heart disease, and preload insufficiency. We tested the influence of body position (supine vs. seated) on hemodynamic classification both at rest and during exercise. We enrolled patients with exercise intolerance due to dyspnea who were referred for exercise RHC at the Cleveland Clinic. Patients were randomized (1:1) to exercise in seated or supine position to a goal of 60 W followed by maximal exercise in the alternate position. We analyzed 17 patients aged 60.3 ± 10.9 years, including 13 females. At rest in the sitting position, patients had significantly lower right atrial pressure (RAP), mean pulmonary artery pressure (mPAP), pulmonary artery wedge pressure (PAWP) and cardiac index (CI). In every stage of exercise (20, 40, and 60 W), the RAP, mPAP, and PAWP were lower in the sitting position. Exercise in the sitting position allowed the identification of preload insufficiency in nine patients. Exercise in either position increased the identification of postcapillary pulmonary hypertension (PH). Body position significantly influences hemodynamics at rest and with exercise; however, mPAP/CO and PAWP/CO were not positionally affected. Hemodynamic measurements in the seated position allowed the detection of preload insufficiency, a condition that was predominantly identified as no PH during supine exercise.

Enhancing Olfactory Loss in COVID-19: The Impact of Body Position

Objective: To understand that COVID-19-induced hyposmia may fluctuate with spatial position. Introduction: COVID-19-induced hyposmia, exacerbated by supination, has yet to heretofore been described. Methods: Case Study: A 52-year-old right-handed woman was ansate until two years before presentation when she developed cold symptoms and sudden onset of loss of smell and taste, with a positive Reverse Transcription-Polymerase Chain Reaction test for COVID-19. Over three weeks, her smell and taste gradually returned to 85% of normal. She reported that her smell and taste would markedly worsen when she would lie down, to 30% of normal, but would improve with standing, moving, and sitting. Even reclining for a short nap would cause her sense of smell to drop, requiring her to stand for hours before her smell would recover, which caused her to fear sleeping and forced her to move around constantly. She markedly altered her lifestyle because of her fear of sleeping and assiduously avoided lying down: when so overwhelmed by tiredness that she must sleep, she would sleep sitting up. Results: Chemosensory Testing: Olfaction: Brief Smell Identification Test: 9 (normosmia). Alcohol Sniff Test: 3 (anosmia). Dirhinus amyl (pentyl) acetate Test: -7.0 (hyperosmia). Retronasal Olfaction: Retronasal Index: 8 (normosmia). Gustation: Phenylthiocarbamide Taste Test: 10 (normogeusia). Discussion: Despite cerebral autoregulation, recumbency may function to decrease venous return, altering calcium concentrations and hence olfactory ability. In the supine orientation, intrathoracic pressure increases, thus mimicking the Valsalva maneuver. This further increases intracranial pressure, decreases cerebral blood flow, and increases cerebral carbon dioxide. Perhaps this causes increased gamma-aminobutyric acid, an inhibitory neurotransmitter within the olfactory bulb, which reduces associated olfactory ability. Peradventure assuming the supine position induces general relaxation and stage. One sleep. Sleep reduces the intensity of perceptual experiences of all the senses, including the olfactory sense [1]. On the other hand, the supine and relaxed state may induce a positive effect. Based on Wolpe's reciprocal inhibition principle, such a relaxed effect causes fear inhibition, whereby there cannot be coexistent simultaneous opposite emotions [2]. Since fear has been demonstrated to improve olfactory ability, assuming the supine position induces relaxation and thus reduces fear-induced increased olfactory ability (Yakov, 2013; Keedwel, 2005). On the other hand, assuming the supine position may induce a kinesthetic distraction, changing the focus of attention away from chemosensation to a change in position. Lying in the lateral decubitus position possibly causes a modification in the olfactory cycle with greater engorgement in the inferiorly situated nostril, which may have a lesser olfactory ability [1]. In those with olfactory deficits after COVID-19 or other conditions, a reduced olfactory ability with lying down may have significant health risks. Further investigation into the impact of position on those with olfactory deficits from all sources, including COVID-19, is warranted.

Adverse outcomes of artificial pneumothorax under right bronchial occlusion for patients with thoracoscopic-assisted oesophagectomy in the prone position versus the semiprone position.

BackgroundThere are few studies on the impact of body position on variations in circulation and breathing, and it has not been confirmed whether body position changes can reduce the pulmonary complications of thoracoscopic-assisted oesophagectomy.MethodsA single-center retrospective study included patients undergoing thoracoscopic-assisted oesophagectomy in the prone position or semiprone position between 1 July 2020, and 30 June 2021, at the Shanghai Chest Hospital. There were 103 patients with thoracoscopic-assisted oesophagectomy in the final analysis, including 43 patients undergoing thoracoscopic-assisted oesophagectomy in the prone position. Postoperative pulmonary complication (PPC) incidence was the primary endpoint. The incidence of cardiovascular and other complications was the secondary endpoint. Chest tube duration, patient-controlled anaesthesia (PCA) pressing frequency within 24 h, ICU stay, and the postoperative hospital length of stay (LOS) were also collected.ResultsCompared with the semiprone position, the prone position decreased the incidence of atelectasis (12% vs. 30%, P = 0.032). Nevertheless, there were no considerable differences in the rates of cardiovascular and other complications, ICU stay, or LOS (P >0.05). Multivariable logistic regression analysis showed that the prone position (OR = 0.196, P = 0.011), no smoking (OR = 0.103, P <0.001), preoperative DLCO% ≥90% (OR = 0.230, P = 0.003), and an operative time <180 min (OR = 0.268, P = 0.006) were associated with less atelectasis.ConclusionsOur study shows that artificial pneumothorax under right bronchial occlusion one-lung ventilation for patients with thoracoscopic-assisted oesophagectomy in the prone position can decrease postoperative atelectasis compared with the semiprone position.

The effect of body position while coughing on the airborne transmission of pathogens

Given the recent acceptance of the central role of airborne transmission for SARS-CoV-2, increased attention has been paid to the dispersion of respiratory droplets in different scenarios. Studies including numerical simulations have been conducted on methods for breaking the chains of transmission. Here, we present the first such study on the impact of body position while coughing on the dispersion of respiratory droplets. Four scenarios are examined, including normal standing, bending the head at different angles, coughing into the elbow in still air, and a gentle breeze from the front and behind. The model showed that an uncovered cough is dangerous and causes many droplets to enter the environment, posing a cross-contamination threat to the others. Droplets with an initial diameter smaller than 62.5 μm remain suspended in windless air for more than 3 min. In the presence of wind, these droplets move with the wind flow and may travel long distances greater than 3.5 m. The model showed that covering the mouth with the elbow while coughing is clearly the best strategy for reducing airborne transmission of exhaled pathogens. About 62% of the initial number of droplets deposit on the cougher's elbow immediately after the cough and have no chance of spreading through the air in both windless and windy conditions. Covering the cough in windless or light breeze conditions also causes the upward thermal plume around the body to expel many small droplets.

The impact of body position and exercise on the measurement of liver Young’s modulus by real-time shear wave elastography

BACKGROUND: In the past ten years, liver biopsies have been used as a method to accurately diagnose the stage of fibrosis. OBJECTIVE: This study aimed to evaluate whether body position and exercise affect the measurement of liver Young’s modulus of healthy volunteers by real-time shear wave elastography (RT-SWE). Methods: RT-SWE was used to measure liver Young’s modulus in the supine and left lateral positions of 70 healthy volunteers at rest and measure the liver Young’s modulus in the lying position before exercise, and at zero, five, and ten minutes of rest after exercise. RESULTS: The liver Young’s modulus in the left lateral position was significantly higher than in the supine position (P&lt; 0.05), and the measured value in the supine position was more stable than the left lateral position. The liver Young’s modulus measured at zero minutes after exercise was significantly higher than that measured before exercise (P&lt; 0.05). The liver Young’s modulus measured at five minutes after exercise was significantly higher than that measured at zero minutes after exercise (P&lt;0.05) and was not statistically different from the measured value before exercise (P&gt; 0.05). The liver Young’s modulus measured at ten minutes after exercise was significantly higher from that measured at zero minutes after exercise (P&lt; 0.05) and was not statistically different from the measured value at five minutes after exercise (P&gt; 0.05). CONCLUSION: Body position and exercise have a significant impact on the measurement of liver Young’s modulus. It is recommended that the examinees take a supine position during the measurement, and measurement should be conducted at least ten minutes after exercise.

Impact of Body Position on Lung Deposition of Nebulized Surfactant in Newborn Piglets on Nasal Continuous Positive Airway Pressure

Introduction: The ideal body position during surfactant nebulization is not known. Objective: The aim of this study was to determine whether body positioning during surfactant nebulization influences surfactant distribution and deposition in the lungs. Methods: Twenty-four 12- to 36-h-old full-termpiglets (1.3–2.2 kg) on nasal continuous positive airway pressure (nCPAP) were randomized into four groups: lateral decubitus with right or left side up, prone or supine positions (n = 6 each). All animals received 200 mg kg^–1 of poractant alfa mixed with 200 MBq of ^99mtechnetium-nanocolloid via a customized eFlow-Neos investigational vibrating-membrane nebulizer. Surfactant deposition (percentage of the administered dose) was measured by gamma scintigraphy. Results: Comparing all groups, the mean total lung surfactant deposition was significantly higher in the prone position (32.4 ± 7.7%, p = 0.03). The deposition in this group was higher in the right lung (21.0 ± 8.6 vs. 11.3 ± 5.7%, p = 0.04). When nebulization was performed in the lateral decubitus, most of the surfactant was found in the dependent lung, regardless of which side the piglet lay on (right side up 15.3 ± 1.0 vs. 3.4 ± 1.0%, p = 0.06, and left side up 11.2 ± 9.8 vs. 1.8 ± 0.7%, p = 0.04). Conclusions: In spontaneously breathing animals on nCPAP, the prone position yielded the highest lung dose. Higher deposition rates in the dependent lung while on lateral decubitus indicates that deposition was also influenced by gravity.

Microclimate measurements at the skin surface: iButton holder design and impact of body position

Microclimate measurements at the skin surface: iButton holder design and impact of body position

Does size matter concerning impact of position on oxygenation status in spontaneously breathing patients with unilateral effusion?

BackgroundInconsistent and contradictory findings have appeared in the literature concerning the impact of body position on oxygenation in pleural effusion.MethodsWe attempted to elucidate whether the size of the pleural effusion...

Effect of position and weight force on inferior vena cava diameter – Implications for arrest-related death

The physiology of many sudden, unexpected arrest-related deaths (ARDs) proximate to restraint has not been elucidated. A sudden decrease in central venous return during restraint procedures could be physiologically detrimental. The impact of body position and applied weight force on central venous return has not been previously studied. In this study, we use ultrasound to measure the size of the inferior vena cava (IVC) as a surrogate of central venous return in the standing position, prone position, and with weight force applied to the thorax in the prone position. This was a prospective, observational study of volunteer human subjects. The IVC was visualized from the abdomen in both the longitudinal and transverse section in the standing and prone positions without weight force applied, and with 100 lbs (45 kg) and 147 lbs (67 kg) of weight force on the upper back in the prone position. Maximum and minimum measurements were determined in each section to account for possible respiratory variation of the IVC. The IVC significantly decreased in size with each successive change: from standing to prone, from prone to prone with 100 lbs (45 kg) weight compression, from prone with 100 lbs (45 kg) weight compression to prone with 147 lbs (67 kg) weight compression (p < 0.0001). The vital sign measurements had no statistical change. The physiology involved in many sudden, unexpected ARDs has not been elucidated. However, in our study, we found a significant decrease in IVC diameter with weight force compression to the upper thorax when the subject was in the prone position. This may have implications for the tactics of restraint to aid in the prevention of sudden, unexpected ARD cases.

Short-term stability of resting heart rate variability: influence of position and gender

Heart rate variability (HRV) is utilized within laboratory and clinical settings as a noninvasive indicator of cardiac autonomic modulation. Past research has utilized a wide variety of resting methodologies and, as such, it is difficult to draw conclusions on the nature of HRV from different studies. Therefore, the current study aimed to assess the short-term stability of resting HRV during a 40-min resting trial and the impact of body position and gender on this short-term stability. Resting HRV was determined from 40-min trials in 3standard positions (supine, seated, and standing) for healthy males (n = 14) and females (n = 16). Time-domain, geometric, and frequency-domain measures of resting HRV were examined during consecutive 10-min segments using a 3-way ANOVA (time× position× gender) and Tukeys' post-hoc tests with reproducibility assessed by intraclass correlation coefficients (ICC) and coefficients of variation. During rest, most HRV measures fluctuated over time, were greater in the supine compared to the standing position, and were greater for males compared with females. Variables that reflected primarily vagal modulations of heart rate remained stable, whereas other HRV measures varied over time. The majority of HRV variables exhibited substantial to excellent short-term reproducibility (ICC> 0.6) with time-domain and geometric measures of HRV demonstrating greater values compared with frequency-domain parameters. Based on the current results, the recording and analysis of HRV at 0-10min of rest was recommended as a standardized protocol for the assessment of resting HRV in any standard position for either gender during laboratory and (or) clinical settings.

Impact of body position on central and peripheral hemodynamic contributions to movement-induced hyperemia: implications for rehabilitative medicine

This study used alterations in body position to identify differences in hemodynamic responses to passive exercise. Central and peripheral hemodynamics were noninvasively measured during 2 min of passive knee extension in 14 subjects, whereas perfusion pressure (PP) was directly measured in a subset of 6 subjects. Movement-induced increases in leg blood flow (LBF) and leg vascular conductance (LVC) were more than twofold greater in the upright compared with supine positions (LBF, supine: 462 ± 6, and upright: 1,084 ± 159 ml/min, P < 0.001; and LVC, supine: 5.3 ± 1.2, and upright: 11.8 ± 2.8 ml·min⁻¹ ·mmHg⁻¹, P < 0.002). The change in heart rate (HR) from baseline to peak was not different between positions (supine: 8 ± 1, and upright: 10 ± 1 beats/min, P = 0.22); however, the elevated HR was maintained for a longer duration when upright. Stroke volume contributed to the increase in cardiac output (CO) during the upright movement only. CO increased in both positions; however, the magnitude and duration of the CO response were greater in the upright position. Mean arterial pressure and PP were higher at baseline and throughout passive movement when upright. Thus exaggerated central hemodynamic responses characterized by an increase in stroke volume and a sustained HR response combined to yield a greater increase in CO during upright movement. This greater central response coupled with the increased PP and LVC explains the twofold greater and more sustained increase in movement-induced hyperemia in the upright compared with supine position and has clinical implications for rehabilitative medicine.

The impact of body position on intra-abdominal pressure measurement: A multicenter analysis*

Elevated intra-abdominal pressure (IAP) is a frequent cause of morbidity and mortality among the critically ill. IAP is most commonly measured using the intravesicular or "bladder" technique. The impact of changes in body position on the accuracy of IAP measurements, such as head of bed elevation to reduce the risk of ventilator-associated pneumonia, remains unclear. Prospective, cohort study. Twelve international intensive care units. One hundred thirty-two critically ill medical and surgical patients at risk for intra-abdominal hypertension and abdominal compartment syndrome. Triplicate intravesicular pressure measurements were performed at least 4 hours apart with the patient in the supine, 15 degrees , and 30 degrees head of bed elevated positions. The zero reference point was the mid-axillary line at the iliac crest. Mean IAP values at each head of bed position were significantly different (p < 0.0001). The bias between IAPsupine and IAP15 degrees was 1.5 mm Hg (1.3-1.7). The bias between IAPsupine and IAP30 degrees was 3.7 mm Hg (3.4-4.0). Head of bed elevation results in clinically significant increases in measured IAP. Consistent body positioning from one IAP measurement to the next is necessary to allow consistent trending of IAP for accurate clinical decision making. Studies that involve IAP measurements should describe the patient's body position so that these values may be properly interpreted.