Endotypic traits of supine position and supine-predominant obstructive sleep apnoea in Asian patients.

BACKGROUND: Over half of all cases of obstructive sleep apnoea (OSA) are classified as supine-related OSA; however, the pathological endotype during supine position is not fully understood. This study aims to investigate the endotypic traits of supine-predominant OSA and explore the variations in endotypic traits between the supine and lateral positions. METHODS: We prospectively recruited 689 adult patients with OSA from a single sleep centre between April 2020 and December 2022. Endotypic traits, namely arousal threshold, collapsibility, loop gain and upper airway muscle compensation, were retrieved from polysomnographic signals. We identified spOSA by a supine to non-supine apnoea-hypopnoea index (AHI) ratio >2. We cross-sectionally compared demographic and endotypic traits between supine-predominant OSA and non-positional OSA and examined the associations between supine-predominant OSA and endotypic traits. Additionally, we compared the changes in endotypic traits between supine and lateral positions in patients with supine-predominant OSA and non-positional OSA. RESULTS: In our study sample, 75.8% of patients were identified as having supine-predominant OSA. Compared to non-positional OSA, supine-predominant OSA was associated with low collapsibility (ß= -3.46 %eupnoea, 95% CI -5.93- -1.00 %eupnoea) and reduced compensation (ß= -6.79 %eupnoea, 95% CI -10.60- -2.99 %eupnoea). When transitioning from the lateral to supine position, patients with supine-predominant OSA had a substantial decrease in compensation compared to those with non-positional OSA (-11.98 versus -6.28 %eupnoea). CONCLUSIONS: Supine-predominant OSA is the prevalent phenotype of OSA in Asian patients. Inadequate upper airway compensation appears to be a crucial underlying pathology in patients with supine-predominant OSA.

Orthostatic variation of pulmonary artery pressure in ambulatory heart failure patients.

AIM: To study effect of change in position (supine and standing) on pulmonary artery pressure (PAP) in ambulatory heart failure (HF) patients. METHODS: Seventeen patients with CardioMEMS® sensor and stable heart failure were consented and included in this single center study. Supine and standing measurements were obtained with at least 5 min interval between the two positions. These measurements included PAP readings utilizing the manufacturer handheld interrogator obtaining 10 s data in addition to the systemic blood pressure and heart rate recordings. RESULTS: Mean supine and standing readings and their difference (Δ) were as follows respectively: Systolic PAP were 33.4 (± 11.19), 23.6 (± 10) and Δ was 9.9 mmHg (p = 0.0001), diastolic PAP were 14.2 (± 5.6), 7.9 (± 5.7) and Δ was 6.3 mmHg (p = 0.0001) and mean PAP were 21.8 (± 7.8), 14 (± 7.2) and Δ was 7.4 mmHg (p = 0.0001) while the systemic blood pressure did not vary significantly. CONCLUSION: There is orthostatic variation of PAP in ambulatory HF patients demonstrating a mean decline with standing in diastolic PAP by 6.3 mmHg, systolic PAP by 9.9 mmHg and mean PAP by 7.4 mmHg in absence of significant orthostatic variation in systemic blood pressure or heart rate. These findings have significant clinical implications and inform that PAP in each patient should always be measured in the same position. Since initial readings at the time of implant were taken in supine position, it may be best to use supine position or to obtain a baseline standing PAP reading if standing PAP is planned on being used.

A review of supine position related obstructive sleep apnea: Classification, epidemiology, pathogenesis and treatment.

Supine related obstructive sleep apnea (OSA) is the most common clinical and physiological phenotype of OSA. This condition is recognizable by patients, their families and through polysomnographic recordings. Commonly used definitions distinguish the presence of supine related OSA when respiratory events occur at twice the frequency when the patient lies in the supine compared to non-supine sleeping positions. Recent physiology studies have demonstrated that airway obstruction arises more commonly in the supine position particularly at the level of the soft palate and epiglottis. Increased airway collapsibility is reliability observed supine relative to lateral position. To a lesser extent, changes in control of breathing favour less stable ventilation when the supine sleeping posture is adopted. Many treatments have been developed and trialled to help patients avoid sleeping on their back. The last 10 years has seen the emergence of vibrotactile warning devices that are worn on the patients' neck or chest. High quality randomized controlled trial data is accumulating on the efficacy and common pitfalls of the application of these treatments.

Variation in cardiopulmonary restoration due to bodily posture post-submaximal exercise in collegiate athletes.

BACKGROUND: The body's anatomical position can influence the autonomic response to return to homeostasis following high intensity exercise. Discrepancies exist as to which body position is considered optimal and practical. This study intends to examine three recovery positions post submaximal exercise to determine which body position would be the most efficient in terms of excess post-exercise oxygen consumption and heart rate recovery. METHODS: NCAA Division I athletes (N.=17) from multiple sport teams completed three submaximal exercise tests utilizing the Bruce Protocol. Excess post-exercise oxygen consumption and heart rate recovery were measured at peak exercise and at 1-, 5-, and 10-minute time intervals during the recovery phase while assuming a recovery position: supine, trunk forward leaning, and standing vertical. RESULTS: Statistical analysis showed the 1-minute excess post-exercise oxygen consumption associated with supine recovery (1725±348 mL/kg) was significantly greater than standing vertical (1578±340 mL/kg, P=0.024). At 5 minutes, supine excess post-exercise oxygen consumption (3557±760 mL/kg) was significantly less than trunk forward leaning (4054±777 mL/kg, P=0.0001) and trunk forward leaning was significantly greater than standing vertical (3776±700 mL/kg, P=0.008). At 10 minutes, supine excess post-exercise oxygen consumption (5246±961 mL/kg) was significantly less than both the standing vertical position (5878±1042 mL/kg, P=0.0099), and the trunk forward leaning position (6749±1223 mL/kg, P<0.0001). Supine had the highest heart rate recovery at 1-, 5-, and 10-minutes post exercise. CONCLUSIONS: The supine position proved to be the most optimal during the 10-minute recovery period, while the trunk forward leaning position showed to be a more advantageous position for short-term recovery.

Can body position be arrhythmogenic?

INTRODUCTION: Palpitations occurring in specific body positions are often reported by patients, but the effect of body position on arrhythmia has received little research attention. We hypothesize that resting body position can exert pro-arrhythmogenic effects in various ways. For example, lateral body position is known to increase change atrial and pulmonary vein dimensions. METHODS: This observational study capitalizes on overnight polysomnography (PSG) recordings from a tertiary sleep clinic. PSGs were retrieved based on any mention of cardiac arrhythmia in the clinical report, irrespective of primary sleep diagnosis or (cardiac) comorbidities. Every instance of atrial ectopy was annotated and subgroups with a homogenous rate of atrial ectopy were created based on the Dunn index. A generalized linear mixed-effects model using age, sex, gender, sleep stage and body position was used to analyse the total amount of atrial ectopy in each combination of sleep stage and body position. Backward elimination was then performed to select the best subset of variables for the model. Presence of a respiratory event was then added to the model for the subgroup with a high atrial ectopy rate. RESULTS: PSGs of 22 patients (14% female, mean age 61y) were clustered and analysed. Body position, sleep stage, age or sex did not have a significant effect on atrial ectopy in the subgroup with a low rate of atrial ectopy (N = 18). However, body position did significantly affect the rate of atrial ectopy in the subgroup with a high rate of atrial ectopy (N = 4; 18%). Respiratory events significantly altered the atrial ectopy rate in only three body positions across two patients. DISCUSSION: In each individual with a high rate of atrial ectopy, the rate of atrial ectopy was significantly higher in either left or right decubital or supine position. Increase in atrial wall stretch in lateral decubital position and obstructive respiratory events in positional sleep apnea are two possible pathophysiological mechanisms, while avoidance of a body position due to symptomatic atrial ectopy in that position is an important limitation. CONCLUSION: In a selected cohort of patients with a high rate of atrial ectopy during overnight polysomnography, the occurrence of atrial ectopy is related to resting body position.

Supine hypertension: A state of the art.

Patients with cardiovascular autonomic failure (AF) may suffer from neurogenic supine hypertension (nSH), defined as systolic blood pressure (SBP) ≥140 mmHg and/or diastolic blood pressure ≥90 mmHg, after 5 min of rest in the supine position, combined with neurogenic orthostatic hypotension (nOH) in approximately 50% of the cases. nSH may be the manifestation of central or peripheral autonomic lesions. Long-term risks are hypothesized with SH, including renal dysfunction, left ventricular hypertrophy, cerebrovascular disease and cognitive impairment. Yet, large longitudinal studies investigating long-term outcomes of nSH are lacking. In clinical practice, nSH should be investigated in patients with nOH. Office screening should be performed measuring supine BP immediately after lying down and 5 min later, combined with BP measurement on active or passive standing. Home BP recordings performed by patients themselves may also be useful, while 24 h-Ambulatory Blood Pressure Monitoring (ABPM) may allow for detection of nocturnal hypertension and confirm the diagnosis. Current expert recommendations suggest treatment interventions if SBP exceeds 160-180 mmHg. Non-pharmacological strategies represent the first-line treatment approach and include head-up sleeping, avoiding supine position during the daytime, and having a snack before bedtime to lower supine BP using post-prandial hypotension. Pharmacological treatments may be considered if severe nSH persists. Short-acting antihypertensive medications administered at bedtime are preferably used in order to selectively lower supine BP and reduce pressure diuresis without worsening daytime hypotension.

The outcome of oral appliance therapy on position-dependent obstructive sleep apnea: A multicenter randomized controlled trial.

INTRODUCTION: This multicenter trial on patients with obstructive sleep apnea (OSA) treated with an oral appliance aimed to determine the effect of sleeping positions. METHODS: A cohort of 314 patients with OSA were enrolled and evaluated at 8 weeks and 1 year, focusing on treatment effects. At baseline and the 2 follow-ups, new polygraphic registration comparing the proportion of treatment responders without position-dependent OSA (non-position-dependent OSA [non-POSA]) and with POSA was used. RESULTS: At the 8-week and 1-year follow-up, 205 and 139 patients were included, respectively. The proportion of responders (apnea-hypopnea index [AHI] <10 and/or ≥50% reduction in AHI) was 56% for the non-POSA group and 69% for the POSA group (not significant [NS]). The responders increased at the 1-year follow-up: 68% and 77% for the non-POSA and POSA groups (NS), respectively. The absolute change in AHI in all sleeping positions at 8 weeks was -12.9 (interquartile range, -25.0 to -0.5) in the non-POSA group and -10.5 (interquartile range, -19.9 to -5.3; NS) in the POSA group. However, the decrease in supine AHI was significantly greater among subjects with POSA. In contrast, the decrease in nonsupine AHI was significantly greater in the non-POSA group, an effect that remained at the 1-year follow-up. CONCLUSIONS: Our hypothesis that subjects with POSA at baseline would have a higher treatment response rate after oral appliance treatment compared with subjects without POSA was rejected. However, those with POSA had a significantly higher supine AHI decrease, and those without POSA had significantly less nonsupine AHI.

Anesthesiology trainees performing flexible scope intubation in spontaneously breathing patients in the left lateral position and the supine position: a prospective randomized trial.

BACKGROUND: Flexible scope intubation is an important airway management skill that requires hands-on training in a real airway. We compared flexible scope intubation by trainees between patients in the left lateral and supine positions. METHODS: Forty patients aged 20 to 80 years with American Society of Anesthesiologists physical status class I to III were scheduled for elective surgery under general endotracheal anesthesia in Ramathibodi Hospital from February 2020 to June 2020. Patients were randomly assigned to be intubated in one of two positions: supine (Group S) or left lateral (Group L). Trainees performed flexible scope intubation in sedated patients under the supervision of an attending anesthesiologist. Intubation success, time to successful intubation, number of attempts, airway adjustment maneuvers, and hemodynamic changes were compared between groups. RESULTS: Patient characteristics did not differ between groups except for Mallampati airway classification. The rate of successful intubation on the first attempt and intubation time did not significantly differ between groups. The proportion of patients who required a jaw thrust during intubation was significantly lower in Group L (10.5% vs. 85%; P < 0.01). Blood pressure and oxygen saturation declined in both groups after intubation. The relative risk of desaturation in patients in the left lateral position compared with the supine position was 0.44 (0.1649-1.1978). CONCLUSION: The rate of successful flexible scope intubation on the first attempt and intubation time did not differ between the groups. The proportion of patients who required a jaw thrust maneuver was significantly lower in patients in the left lateral position. TRIAL REGISTRATION: https://www.thaiclinicaltrials.org/ ( TCTR20200208001 ) on 08/02/2020.

Why upright standing men urinate more efficiently than in supine position: A morphological analysis with real-time magnetic resonance imaging.

PURPOSE: Few studies have examined the effects of body position on urination efficiency morphologically. We aimed to dissect out the anatomical changes of pelvic organs during urination in the upright and supine positions by a real-time magnetic resonance imaging (rtMRI) system. METHODS: Thirteen healthy male volunteers aged 26-60 years were included in the study. The sagittal real-time two-dimensional images were taken to evaluate urinary efficiency, along with change in six morphological indices at the time of storage and the beginning of voiding, in both upright ant supine positions. RESULTS: Urination was more efficient in upright position than in supine position, as expressed by higher average rate of bladder emptying (9.9 ± 4.2 vs. 6.8 ± 2.9 ml/s, p < 0.05) and also by fewer participants showing significant residual urine (1/13 vs. 7/13, p < 0.05). At the onset of voiding in standing position, the levator ani (LA) muscle moves downward and backward followed by descent of the bladder neck and rotation of the prostate around the symphysis. Such changes were expressed by two morphological indices. One was posterior vesicourethral angle at the start of voiding, 152 ± 7 versus 140 ± 1 in upright and supine position (p < 0.05). The other index was the change in angle between the LA line and pubo-coccygeal line in upright and supine position, 9.4 ± 9.9 versus 1.6 ± 7.9 before voiding (p < 0.05) and 30.2 ± 14.0 versus 17.3 ± 12.9 after the start of voiding (p < 0.05). CONCLUSION: The dynamic relaxation of LA seemed to be a key movement that enables more efficient urination in standing position than in supine position.

Noninvasive intracranial pressure monitoring in women with migraine.

This cross-sectional study aimed to compare the waveform morphology through noninvasive intracranial pressure (ICP-NI) measurement between patients with migraine and controls, and to analyze the association with clinical variables. Twenty-nine women with migraine, age 32.4 (11.2) years and headache frequency of 12.6 (7.5) days per month and twenty-nine women without headache, age 32.1 (9.0) years, were evaluated. Pain intensity, migraine disability, allodynia, pain catastrophizing, central sensitization and depression were evaluated. The ICP-NI monitoring was performed by a valid method consisting of an extracranial deformation sensor positioned in the patients' scalp, which allowed registration of intracranial pressure waveforms. Heart rate and blood pressure measurements were simultaneously recorded during 20 min in the supine position. The analyzed parameter was the P2/P1 ratio based on mean pulse per minute which P1 represents the percussion wave related to the arterial blood pression maximum and P2 the tidal wave, middle point between the P1 maximum and the dicrotic notch. There was no between-groups difference in the P2/P1 ratio (mean difference: 0.04, IC95%: -0.07 to 0.16, p = 0.352, F (1,1) = 0.881) adjusted by body mass index covariable. The Multiple Linear Regression showed non-statistical significance [F (5,44) = 1.104; p = 0.372; R2 = 0.11)] between the P2/P1 ratio and body mass index, presence of migraine, central sensitization, pain catastrophizing and depression. We found no correlation (p > 0.05) between P2/P1 ratio and migraine frequency, migraine onset, pain intensity, pain intensity at day of examination, disability, allodynia. Migraine patients did not present alterations in the waveform morphology through ICP-NI compared to women without headache and no association with clinical variables was found.

Prognostic value of postural hypotension in hospitalized patients with heart failure.

Although postural hypotension (PH) is reportedly associated with mortality in the general population, the prognostic value for heart failure is unclear. This was a post-hoc analysis of FRAGILE-HF, a prospective multicenter observational study focusing on frailty in elderly patients with heart failure. Overall, 730 patients aged ≥ 65 years who were hospitalized with heart failure were enrolled. PH was defined by evaluating seated PH, and was defined as a fall of ≥ 20 mmHg in systolic and/or ≥ 10 mmHg in diastolic blood pressure within 3 min after transition from a supine to sitting position. The study endpoints were all-cause death and heart failure readmission at 1 year. Predictive variables for the presence of PH were also evaluated. PH was observed in 160 patients (21.9%). Patients with PH were more likely than those without PH to be male with a New York Heart Association classification of III/IV. Logistic regression analysis showed that male sex, severe heart failure symptoms, and lack of administration of angiotensin-converting enzyme inhibitors were independently associated with PH. PH was not associated with 1-year mortality, but was associated with a lower incidence of readmission after discharge after adjustment for other covariates. In conclusion, PH was associated with reduced risk of heart failure readmission but not with 1-year mortality in older patients with heart failure.

Comparison of Effects of Extubation in Prone and Supine Positions in Patients Operated for Lumbar Disc Herniation.

AIM: To observe the effects of prone position extubation on respiratory side effects and hemodynamic parameters in patients who underwent lumbar spinal surgery. MATERIAL AND METHODS: This prospective observational study included 60 patients extubated in either the prone (n=30) or supine (n=30) positions. Heart rate, noninvasive arterial blood pressure, peripheral oxygen saturation, train of four values, and bispectral index values were measured and recorded in all patients during operation and at the time of anesthetic agent discontinuation, before and after extubation. The Aldrete recovery score was recorded together with the severity of cough during emergence and recovery. Sore throat visual analog scale (VAS) score was recorded at the first and sixth hours after extubation. Incidents such as nausea, vomiting, respiratory failure, uncontrolled airway, and decreased saturation were also recorded. RESULTS: The number and severity of cough (p < 0.05) and sore throat VAS (p < 0.001) were lower in the prone group. Postextubation breath holding was more frequent in the supine group (p < 0.001). Aldrete recovery scores were higher in the prone group (p < 0.05). Heart rate and mean arterial pressure values were not significantly different in the prone group during the emergence and recovery period as compared with the supine group (p > 0.05). CONCLUSION: Extubation in the prone position after lumbar spinal surgery provides more comfortable emergence and recovery periods with less alteration of respiratory status and a better recovery profile.

Intraoperative pressure monitoring of the lower leg for preventing compression-related complications associated with the lithotomy position.

BACKGROUND: Several serious complications are associated with the lithotomy position, including well-leg compartment syndrome and peroneal nerve paralysis. The aims of this study were to identify risk factors for the intraoperative elevation of lower leg pressure and to evaluate the effectiveness of monitoring external pressure during surgery for preventing these complications. METHODS: The study included 106 patients with a diagnosis of sigmoid colon or rectal cancer who underwent elective laparoscopic surgery between June 2019 and December 2020. We divided the posterior side of the lower leg into four parts (upper outside, upper inside, lower outside, lower inside) and recorded the peak pressure applied to each area at hourly intervals during surgery (called "regular points") and when the operating position was changed (e.g., by head-tilt or leg elevation; called "points after change in position"). When the pressure was observed to be higher than 50 mmHg, we adjusted the position of the leg and re-recorded the data. Data on postoperative leg-associated complications were also collected. RESULTS: The pressure was measured at a total of 1125 points (regular, n = 620; after change of position, n = 505). The external pressure on the upper outer side of the right leg (median, 36 mmHg) was higher than that on any other area of the lower leg. The pressure increase to more than 50 mmHg was observed not only during the change of position (27.5%) but also during regular points (22.4%). Bodyweight, strong leg elevation, and low head position were identified as factors associated with increased external pressure. There have been no compression-related complications in 534 cases at our institution since the introduction of intraoperative pressure monitoring. CONCLUSIONS: Several risk factors associated with increased external pressure on the lower leg were identified. Intraoperative pressure monitoring might help reduction of pressure-related complications, needing further and larger prospective data collections.

The effect of body position on maternal cardiovascular function during sleep and wakefulness in late pregnancy.

INTRODUCTION: An association between the increased risk of late stillbirth and the maternal supine sleeping position has been recently established. The risk of stillbirth following supine sleep has been suspected to occur as a result of aortocaval compression by the gravid uterus. A number of studies conducted during wakefulness have reported compromised cardiovascular function during supine rest, as demonstrated by reductions in cardiac output, blood pressure and utero-placental blood flow. It remains unclear whether similar effects are also present during sleep, due to the presence of key sleep-specific changes in cardiovascular function. OBJECTIVE: To investigate the changes in maternal cardiovascular function between the supine and left-lateral positions during wakefulness and non-rapid eye movement (NREM) sleep in late pregnancy. METHODS: Twenty-nine women with a singleton pregnancy between 24.7 and 36.7 weeks' gestation participated in a single overnight sleep study. Physiological measures (blood pressure, heart rate, heart rate variability - HRV, and pulse arrival time - PAT) were measured and recorded throughout the night using standard polysomnography equipment and the Portapres Model-2 device. As the present study evaluated cardiovascular changes during natural rest and sleep in pregnancy, participants were not given explicit instructions on which position to adopt. Body position was continuously recorded using a position monitor and verified with video recording. RESULTS: No changes in systolic, diastolic or mean arterial blood pressure were observed between the left-lateral and supine positions during wakefulness or sleep. However, heart rate was significantly higher in the supine position compared to the left during wakefulness (p= .03), with a similar trend present during sleep (p= .11). A significantly shorter PAT was measured in the supine position (compared to the left) during wakefulness (p= .01) and sleep (p= .01). No change in HRV measures was observed between the left and supine positions in either state. CONCLUSION: Blood pressure did not appear to differ significantly between the left-lateral and supine positions during wakefulness and sleep. The lack of blood pressure differences may reflect elevated sympathetic activity during rest and sleep in the supine position (compared to the left), suggesting that some degree of compensation for aortocaval compression may still be possible during sleep.

The Recumbent Position Affects Nasal Resistance: A Systematic Review and Meta-Analysis.

OBJECTIVE: Nasal diseases are among the main motives for the early discontinuation of continuous positive airway pressure therapy and for long-term therapeutic compliance with mandibular advancement device. Although our clinical experience leads us to the belief that recumbency impacts nasal airflow in some patient populations, there is no consensus regarding the magnitude of this effect and the specific group of patients who are the most affected by this condition. In this study, we conducted a meta-analysis to assess the effect of the recumbent position on nasal resistance and nasal airflow. REVIEW METHODS: PubMed (Medline), Cochrane Library, EMBASE, Scopus, and SciELO databases were checked for relevant studies by two members of the YO-IFOS study group. The two authors extracted the data. The main outcome was expressed as the difference between nasal resistance and nasal airflow before and after recumbency. RESULTS: Nine studies with a total population of 291 individuals were included in the meta-analysis for nasal resistance after recumbency. We found a statistically significant difference in nasal airway resistance of -0.18 Pa sec/cm3 as compared to before and after recumbency through rhinomanometry (RMM) analysis. A subgroup analysis revealed a variation of -0.20 Pa sec/cm3 for patients with snoring or sleep apnea and - 0.10 Pa sec/cm3 for healthy individuals. Regarding nasal airflow measured with RMM, three studies (n = 32) in asymptomatic controls revealed a statistically significant difference of 47.33 ml/sec. CONCLUSIONS: Recumbency increases nasal resistance and diminishes nasal airflow. This finding is of utmost importance in snorers and sleep apnea patients. Laryngoscope, 132:6-16, 2022.

How motor elements at 3 months influence motor performance at the age of 6 months.

ABSTRACT: One of the most important achievements of infancy is mobility, through which the child gradually becomes independent and can discover new places and objects. One form of mobility that occurs in a child's development is rolling over from supine-to-prone.The assumption of the work was to check whether all particular motor elements from the 3rd month had a comparable effect on development in the 6th month of life.The study population included 119 children, 69 born at term, and 50 born preterm. Children were born at week 38 ±â€Š3 (born at term 40  ±â€Š1/preterm 34 ±â€Š3), with a mean body weight of 3100 ±â€Š814 g (born at term 3462 ±â€Š505/ preterm 2282 ±â€Š788). Pre-term children were assessed at the corrected age. The physiotherapeutic qualitative assessment at the age of 3 months was performed in the prone and supine positions, and the qualitative assessment included 15 elements in the prone position and 15 in the supine position. A detailed mathematical analysis was then performed. Values of Cramer's V coefficient with confidence range, Goodman-Kruskal's coefficient, and the values of the probability coefficient p were given.The position of the scapulae and pelvis (3rd month) had the strongest impact on achieving proper support on the upper extremities in the 6th month of life, while the supine position was most significantly affected by the position of the head, spine, and pelvis.

Prolonged sitting-induced back pain influences abdominal muscle thickness in a sitting but not a supine position.

The current study explored whether (i) abdominal muscle thickness differed between non-painful supine and painful sitting positions and (ii) the sitting position was more reliable and useful than the supine position to discriminate between people with and without prolonged sitting-induced lower back pain (LBP). Participants with and without prolonged sitting-induced LBP participated. The thickness of the transversus abdominis (TrA), internal oblique (IO), and external oblique (EO) muscles was measured using ultrasonography in supine, usual sitting, and upright sitting positions. Analysis of variance was used to compare muscle thickness among the positions. Intraclass correlation coefficients and receiver operating characteristic curves were used to determine which position reliably identified between group. The group with LBP showed significantly greater EO muscle thickness than that without LBP only in the upright sitting position. In the group without LBP, the TrA thickness was significantly greater in the usual and upright sitting positions than in the supine position, but there was no significant difference in TrA thickness among three positions in LBP group. Only EO thickness in the upright sitting position significantly predicted prolonged sitting-induced LBP. The current study suggests that clinicians should assess abdominal activation patterns in the upright sitting rather than supine position before applying abdominal muscle motor control training for patients with prolonged sitting-induced LBP, and to distinguish between those with and without prolonged sitting-induced LBP.

Pierre Robin sequence causes position-dependent obstructive sleep apnoea in infants.

INTRODUCTION: Obstructive sleep apnoea (OSA) and feeding difficulties are key problems for Pierre Robin sequence (PRS) infants. OSA management varies between treatment centres. Sleep positioning represents the traditional OSA treatment, although its effectiveness remains insufficiently evaluated. DESIGN: To complete a polysomnographic (PSG) evaluation of effect of sleep position on OSA in PRS infants less than 3 months of age. We analysed a 10-year national reference centre dataset of 76 PRS infants. PSG was performed as daytime recordings for 67 in the supine, side and prone sleeping position when possible. In most cases, recording included one cycle of non-rapid eye movement (NREM) and rapid eye movement (REM) sleep in each position. RESULTS: One-third of infants (9/76, 12%) had severe OSA needing treatment intervention prior to PSG. During PSG, OSA with an obstructive apnoea and hypopnoea index (OAHI) >5 per hour was noted in 82% (55/67) of infants. OSA was most severe in the supine and mildest in the side or in the prone positions. The median OAHI in the supine, side and prone positions were 31, 16 and 19 per hour of sleep (p=0.003). For 68% (52/67) of the infants, either no treatment or positional treatment alone was considered sufficient. CONCLUSIONS: The incidence of OSA was 84% (64/76) including the nine infants with severe OSA diagnosed prior to PSG. For the most infants, the OSA was sleep position dependent. Our study results support the use of PSG in the evaluation of OSA and the use of sleep positioning as a part of OSA treatment.

Spleen emptying does not correlate with faster oxygen kinetics during a step-transition supine cycling.

This manuscript quantified spleen volume changes and examined the relationship between those changes and oxygen uptake kinetics during supine cycling. Ten volunteers (age = 22 ± 3), completed 3 step transitions from 20 W to their power output at 90% gas exchange threshold. Ultrasonic measurements of the spleen were performed each minute. The largest spleen volume reduction was 105 mL (p = 0.001). No associations existed between i) spleen volumes at rest; and ii) spleen volume changes (%) and tau pulmonary oxygen uptake (τV̇O2p). Larger resting spleen volume and greater emptying do not correlate with a faster τV̇O2p. Novelty: Greater splenic contractions do not augment τV̇O2p, irrespective of spleen emptying and subsequent erythrocyte release.