Prevalence, associated risk factors, and respiratory event distribution of obstructive sleep apnea in children with Down syndrome

PURPOSE

Children with Down Syndrome (DS) have a high prevalence of obstructive sleep apnea (OSA). We aimed to assess OSA prevalence in a single center cohort of children with DS, identify associated risk factors of obstructive respiratory events, and examine the influence of different sleep stages and body positions on respiratory events distribution.

METHODS

Single center retrospective study that included children with DS who underwent overnight polysomnogram (PSG). OSA severity was categorized by obstructive apnea-hypopnea index (OAHI) as mild (1.5-4.9 events/h), moderate (5-9.9 events/h), and severe (≥ 10 events/h). A logistic regression analysis was used to examine the association between OSA-related risk factors in normal and abnormal OAHI category and in REM and Non-REM predominant AHI groups.

RESULTS

PSG data were available for 192 children with a median age of 5 years (IQR 7). OSA prevalence was 82.3% (27.1% mild, 19.8% moderate, and 35.4% severe). A logistic regression model identified BMI and being an African American as significant predictors for OAHI severity. In children with OSA, the median OAHI was 7.6 and obstructive respiratory events were more common in REM sleep and in the supine position. The median REM OAHI was 20 events/h (IQR: 24.4), whereas the median Non-REM OAHI was 5.2 events/h (IQR: 12.6 p < 0.0001). Similarly, supine OAHI was 11.6 (IQR: 19.3) and off supine OAHI was 6.6 (IQR: 11.6, p = 0.0004). Age was a significant predictor (p = 0.012) for Non-REM predominant OSA which was present in 15.2% of children with OSA.

CONCLUSION

Children with DS have a high prevalence of OSA. Higher BMI and being an African American were significant associated risk factors for higher OAHI. Obstructive respiratory events in children with DS occur predominantly in REM sleep and in the supine position. Non-REM predominant distribution of respiratory events was noted in older children with DS.

Ambulatory intracranial pressure in humans: ICP increases during movement between body positions

Introduction

Positional changes in intracranial pressure (ICP) have been described in humans when measured over minutes or hours in a static posture, with ICP higher when lying supine than when sitting or standing upright. However, humans are often ambulant with frequent changes in position self-generated by active movement.

Research question

We explored how ICP changes during movement between body positions.

Material and methods

Sixty-two patients undergoing clinical ICP monitoring were recruited. Patients were relatively well, ambulatory and of mixed age, body habitus and pathology. We instructed patients to move back and forth between sitting and standing or lying and sitting positions at 20 s intervals after an initial 60s at rest. We simultaneously measured body position kinematics from inertial measurement units and ICP from an intraparenchymal probe at 100 Hz.

Results

ICP increased transiently during movements beyond the level expected by body position alone. The amplitude of the increase varied between participants but was on average ∼5 mmHg during sit-to-stand, stand-to-sit and sit-to-lie movements and 10.8 mmHg [95%CI: 9.3,12.4] during lie-to-sit movements. The amplitude increased slightly with age, was greater in males, and increased with median 24-h ICP. For lie-to-sit and sit-to-lie movements, higher BMI was associated with greater mid-movement increase (β = 0.99 [0.78,1.20]; β = 0.49 [0.34,0.64], respectively).

Discussion and conclusion

ICP increases during movement between body positions. The amplitude of the increase in ICP varies with type of movement, age, sex, and BMI. This could be a marker of disturbed ICP dynamics and may be particularly relevant for patients with CSF-diverting shunts in situ.

The clinical applicability of sensor technology with body position detection to combat pressure ulcers in bedridden patients

INTRODUCTION

Pressure Ulcers (PUs) are a major healthcare issue leading to prolonged hospital stays and decreased quality of life. Monitoring body position changes using sensors could reduce workload, improve turn compliance and decrease PU incidence.

METHOD

This systematic review assessed the clinical applicability of different sensor types capable of in-bed body position detection.

RESULTS

We included 39 articles. Inertial sensors were most commonly used (n = 14). This sensor type has high accuracy and is equipped with a 2-4 hour turn-interval warning system increasing turn compliance. The second-largest group were piezoresistive (pressure) sensors (n = 12), followed by load sensors (n = 4), piezoelectric sensors (n = 3), radio wave-based sensors (n = 3) and capacitive sensors (n = 3). All sensor types except inertial sensors showed a large variety in the type and number of detected body positions. However, clinically relevant position changes such as trunk rotation and head of bed elevation were not detected or tested.

CONCLUSION

Inertial sensors are the benchmark sensor type regarding accuracy and clinical applicability but these sensors have direct patient contact and (re)applying the sensors requires the effort of a nurse. Other sensor types without these disadvantages should be further investigated and developed. We propose the Pressure Ulcer Position System (PUPS) guideline to facilitate this.

Effects of Body Position on Cochlear Function in Infants: An Otoacoustic Emission Study

Background

Otoacoustic Emission (OAE) is frequently recorded in various body positions for infants. However, little is available about whether these deviations will produce non-pathological effects on the clinical results. The current study assessed body position's effect on infants' inner ear function.

Methods

Sixty normally hearing infants participated in an analytical cross-sectional study. Distortion-product OAEs (DPOAEs) were measured in the supine, side-lying, and upright positions. The DPOAE amplitude and signal-to-noise ratio (SNR) were recorded across the 1500 to 6000 Hz range.

Results

The mean DPOAE amplitude and SNR values were significantly greater in the upright position than supine and side-lying positions (p < 0.05). These differences were more pronounced in the 3000 to 6000 Hz range. The effects of gender and ear asymmetry on DPOAEs were not statistically significant.

Conclusion

Our findings suggested that the upright position could be regarded as the best position for assessing DPOAEs in infants.

Using intra-breath oscillometry in obesity hypoventilation syndrome to detect tidal expiratory flow limitation: a potential marker to optimize CPAP therapy

BACKGROUND

Continuous positive airway pressure (CPAP) therapy has profound effects in obesity hypoventilation syndrome (OHS). Current therapy initiation focuses on upper airway patency rather than the assessment of altered respiratory mechanics due to increased extrapulmonary mechanical load.

METHODS

We aimed to examine the viability of intra-breath oscillometry in optimizing CPAP therapy for OHS. We performed intra-breath oscillometry at 10 Hz in the sitting and supine positions, followed by measurements at increasing CPAP levels (none-5-10-15-20 cmH2O) in awake OHS patients. We plotted intra-breath resistance and reactance (Xrs) values against flow (V') and volume (V) to identify tidal expiratory flow limitation (tEFL).

RESULTS

Thirty-five patients (65.7% male) completed the study. We found a characteristic looping of the Xrs vs V' plot in all patients in the supine position revealing tEFL: Xrs fell with decreasing flow at end-expiration. Intra-breath variables representing expiratory decrease of Xrs became more negative in the supine position [end-expiratory Xrs (mean ± SD): -1.9 ± 1.8 cmH2O·s·L- 1 sitting vs. -4.2 ± 2.2 cmH2O·s·L- 1 supine; difference between end-expiratory and end-inspiratory Xrs: -1.3 ± 1.7 cmH2O·s·L- 1 sitting vs. -3.6 ± 2.0 cmH2O·s·L- 1 supine, p < 0.001]. Increasing CPAP altered expiratory Xrs values and loop areas, suggesting diminished tEFL (p < 0.001). 'Optimal CPAP' value (able to cease tEFL) was 14.8 ± 4.1 cmH2O in our cohort, close to the long-term support average of 13.01(± 2.97) cmH2O but not correlated. We found no correlation between forced spirometry values, patient characteristics, apnea-hypopnea index and intra-breath oscillometry variables.

CONCLUSIONS

tEFL, worsened by the supine position, can be diminished by stepwise CPAP application in most patients. Intra-breath oscillometry is a viable method to detect tEFL during CPAP initiation in OHS patients and tEFL is a possible target for optimizing therapy in OHS patients.

Effects of changes in trunk inclination on ventilatory efficiency in ARDS patients: quasi-experimental study

BACKGROUND

Trunk inclination from semirecumbent head-upright to supine-flat positioning reduces driving pressure and increases respiratory system compliance in patients with acute respiratory distress syndrome (ARDS). These effects are associated with an improved ventilatory ratio and reduction in the partial pressure of carbon dioxide (PaCO2). However, these physiological effects have not been completely studied, and their mechanisms have not yet been elucidated. Therefore, this study aimed to evaluate the effects of a change in trunk inclination from semirecumbent (45°) to supine-flat (10°) on physiological dead space and ventilation distribution in different lung regions.

RESULTS

Twenty-two ARDS patients on pressure-controlled ventilation underwent three 60-min steps in which trunk inclination was changed from 45° (baseline) to 10° (intervention) and back to 45° (control) in the last step. Tunk inclination from a semirecumbent (45°) to a supine-flat (10°) position resulted in a higher tidal volume [371 (± 76) vs. 433 (± 84) mL (P < 0.001)] and respiratory system compliance [34 (± 10) to 41 (± 12) mL/cmH2O (P < 0.001)]. The CO2 exhaled per minute improved from 191 mL/min (± 34) to 227 mL/min (± 38) (P < 0.001). Accordingly, Bohr's dead space ratio decreased from 0.49 (± 0.07) to 0.41 (± 0.06) (p < 0.001), and PaCO2 decreased from 43 (± 5) to 36 (± 4) mmHg (p < 0.001). In addition, the impedance ratio, which divides the ventilation activity of the ventral region by the dorsal region ventilation activity in tidal images, dropped from 1.27 (0.83-1.78) to 0.86 (0.51-1.33) (p < 0.001). These results, calculated from functional EIT images, indicated further ventilation activity in the dorsal lung regions. These effects rapidly reversed once the patient was repositioned at 45°.

CONCLUSIONS

A change in trunk inclination from a semirecumbent (45 degrees) to a supine-flat position (10 degrees) improved Bohr's dead space ratio and reduced PaCO2 in patients with ARDS. This effect is associated with an increase in tidal volume and respiratory system compliance, along with further favourable impedance ventilation distribution toward the dorsal lung regions. This study highlights the importance of considering trunk inclination as a modifiable determinant of physiological parameters. The angle of trunk inclination is essential information that must be reported in ARDS patients.

Long-form recording of infant body position in the home using wearable inertial sensors

Long-form audio recordings have had a transformational effect on the study of infant language acquisition by using mobile, unobtrusive devices to gather full-day, real-time data that can be automatically scored. How can we produce similar data in service of measuring infants' everyday motor behaviors, such as body position? The aim of the current study was to validate long-form recordings of infant position (supine, prone, sitting, upright, held by caregiver) based on machine learning classification of data from inertial sensors worn on infants' ankles and thighs. Using over 100 h of video recordings synchronized with inertial sensor data from infants in their homes, we demonstrate that body position classifications are sufficiently accurate to measure infant behavior. Moreover, classification remained accurate when predicting behavior later in the session when infants and caregivers were unsupervised and went about their normal activities, showing that the method can handle the challenge of measuring unconstrained, natural activity. Next, we show that the inertial sensing method has convergent validity by replicating age differences in body position found using other methods with full-day data captured from inertial sensors. We end the paper with a discussion of the novel opportunities that long-form motor recordings afford for understanding infant learning and development.

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.

The effect of head rotation on OSA is associated with disease severity: a cross-sectional study

PURPOSE

Head rotation is an effective positional therapy for obstructive sleep apnea (OSA). However, not all OSA patients benefit from head rotation. This study aimed to explore the clinical phenotype of OSA patients who can benefit from head rotation.

METHODS

We performed a retrospective review of 184 consecutive OSA patients who underwent polysomnography. Head rotation in supine position was determined by high-quality video recording. According to the changes in apnea-hypopnea index (AHI) after head rotation, OSA patients were divided into two groups: patients with response to head rotation(HR) and patients without response to head rotation(NHR). Demographic factors and overnight polysomnography were analyzed.

RESULTS

Compared with NHR group, HR group showed significantly lower AHI (51.8 vs 31.5, p < 0.01), time spent with oxygen saturation below 90%(5.3% vs 0.51%, p < 0.01), and higher lowest oxygen saturation(80% vs 86%, p < 0.05). Logistic regression showed that AHI was an independent factor to predict the decrease of AHI in head rotation (OR 0.985, 95% CI 0.970-0.979, p < 0.05). Among mild to moderate group (AHI < 30/h), severe group (30/h ≤ AHI < 60/h), and extremely severe group (AHI ≥ 60/h), the percentage decrease of AHI in head rotation was 18.5%, 9.5%, and 2.6%, respectively. Surprisingly, the percentage decrease of AHI of 6 responders in mild to moderate group was more than 50%.

CONCLUSION

OSA patients who respond well to head rotation have less severe disease, and patients with mild to moderate OSA are more likely to improve and benefit from this position. Our research provides potential strategies and insights into the individual treatment of OSA patients.

Efficacy of body position on gastric residual in preterm infant: a systematic review and meta-analysis

BACKGROUND

Preterm babies are born before completion of 37 weeks of gestational. Compared to term neonates, preterm babies are difficult to adjust to extra uterine life and 15 (11%) millions babies born before 37 weeks of gestation.

PURPOSE

This systematic review and meta-analysis aimed to evaluate evidence concerning the efficacy of body position on gastric residual volume among preterm infants.

METHODS

We conducted a systematic search of studies trials published in PubMed, MEDLINE, CINHAL, Clinical Key, Cochrane Library, and Google scholar. Two authors independently appraised the selected RCTs (Randomized Control Trials) for evaluating the effectiveness of body position on gastric emptying. This systematic review and meta-analysis was conducted based on the Cochrane risk bias assessment tool using Revman 5.3software.

RESULTS

On assessment this systematic review and meta-analysis comprised 289 preterm infants from the included 7 trials, with the sample size ranging from 20-63. The gestational age ranged from 28-37 weeks, with an average gestational age of 31.7 weeks. The age of the participants postnatal ranged from 6.6 days-33.4 days, with an average age of 18±6 days. The weight of the participants during data collection ranged from 1272-2683 grams, with an average of 1795 grams.

CONCLUSION

This systematic review and meta-analysis revealed that right lateral and prone position lesser gastric residual volume in comparison to preterm infants placed in supine and left lateral position.

Comparative analysis of ECG records depending on body position in domestic swine (Sus scrofa domestica)

Background

Electrocardiography is a method widely applied in diagnosing abnormalities in the functioning of the heart muscle in veterinary medicine. It is a non-invasive and easy to perform test helpful in the general examination and a widely used patient monitoring method during anesthesia. Since the 1980s, pigs have become more and more popular companion animals. Moreover, the pig is a widely used model animal in biomedical research. Therefore, there is need to provide them with higher-quality veterinary services, also in emergency situations. It creates new challenges for veterinarians and the need to expand their knowledge of pigs’ treatment as pets. The aim of the planned experiment was to compare the ECG recordings made with two different body positions and determine if any differences occurred. Standard ECG in swine is performed under general anesthesia in the lying position on the left side, for this position of the body have been developed and reported standards in the literature. However, some procedures performed on swine require a different body position, for which there is less data in the literature.

Methods

The study was carried out on 29 Polish landrace pigs weighing in the range of 33–44 kg. The tests were performed under general anesthesia with the same protocol for each animal, placing the animals first lying down on their right side, and then on their backs. The anesthesia protocol included medetomidine, midazolam, ketamine, and propofol. During the examination, ECG records were performed and analyzed in a 12-lead system with software support.

Results

The results show significant differences in electrocardiogram recordings depending on the animal's body position. Those differences mainly concern the amplitude of the P wave and R wave in the recordings and are even more visible comparing the electrocardiograms of the same specimen. There are also some significant differences in the duration of intervals. Based on the obtained results, reference ranges for the right lateral and dorsal positions were developed.

Conclusion

In conclusion, the body position has a significant impact on the ECG recording in swine, therefore performing this examination, chosen normative value tables should be compatible with the position of the examined animal.

The projected frontal area and its components during front crawl depend on lung volume

We examined the influence of lung volume on the vertical body position, trunk inclination, and projected frontal area (PFA) during swimming and the inter-relationships among these factors. Twelve highly trained male swimmers performed a 15 m front crawl with sustained maximal inspiration (INSP), maximal expiration (EXP), and intermediate (MID) at a target velocity of 1.20 m·s^-1 . Using our developed digital human model, which allows inverse kinematics calculations by fitting individual body shapes measured with a three-dimensional photonic image scanner to individually measured underwater motion capture data, vertical center of mass (CoM) position, trunk inclination, and PFA were calculated for each complete stroke cycle. In particular, the PFA was calculated by automatic processing of a series of parallel frontal images obtained from a reconstructed digital human model. The vertical CoM position was higher with a larger lung-volume level (P < 0.01). The trunk inclination was smaller in INSP and MID than in EXP (P < 0.01). PFA was smaller with a larger lung-volume level (P < 0.01). Additionally, there was a significant interaction of vertical CoM position and trunk inclination with PFA (P = 0.006). There was a negative association between PFA and vertical CoM position, and a positive association between PFA and trunk inclination less than the moderate vertical CoM position (each P < 0.05). These results obtained using our methodology indicate that PFA decreases with increasing lung volume due to an increase in vertical CoM position, and additionally due to a decrease in trunk inclination at low-to-moderate lung-volume levels.

Regional oxygenation, perfusion and body and/or head position: Are preterm infants adversely impacted? A systematic review

This review addresses regional oxygenation and perfusion changes for preterm infants and changes with body position, with or without head rotation. Future directions for improving neurodevelopmental and clinical outcomes are suggested. The MEDLINE, Embase and Scopus databases were searched up to July 2021. Fifteen out of 470 studies met the inclusion criteria. All were prospective, observational studies with a moderate risk of bias. Significant variation was found for the baseline characteristics of the cohort, postnatal ages, and respiratory support status at the time of monitoring. When placed in a non-supine position, preterm infants showed a transient reduction in cardiac output and stroke volume without changes to heart rate or blood pressure. No studies reported on long-term neurodevelopmental outcomes. Overall, side lying or prone position does not appear to adversely affect regional, and specifically cerebral, oxygenation or cerebral perfusion. The effect of head rotation on regional oxygenation and perfusion remains unclear.

The effectiveness of different education methods conducted at different times for decreasing the time required for a parturient to position herself for epidural placement

Background

Decreasing the anaesthesia preparation time for primiparas experiencing painful uterine contractions is clinically relevant. This prospective intervention study investigated the effect of various educational methods conducted at different times on body positioning for primiparas undergoing labour analgesia.

Methods

Ninety primiparas who were about to receive labour analgesia were randomly divided into a verbal instruction group, a photo instructions group, and an educational video group for immediate education, and 60 primiparas who were willing to receive labour analgesia but were not in labour were randomly divided into a photo instruction group and an educational video group for advance education. The times required for body positioning were compared.

Results

In the immediate education cohort, the body positioning time in the verbal group (50.48 ± 28.97 s) was significantly longer than those in the photo group (30.47 ± 6.94 s) and the video group (23.14 ± 9.74 s) (P = 0.00). In the advance education cohort, the time in the photo group (17.47 ± 6.48 s) was longer than that in the video group (13.71 ± 7.01 s) (P = 0.042). Whether photos or videos are used, advance education can significantly decrease body positioning time.

Conclusions

Video or photo education for primiparas who are about to receive labour analgesia can decrease the body positioning time and is more effective when provided in advance.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-022-04879-6.

Postural and visual aftereffects to a slanted floor in lying and sitting positions

After lying on a slanted floor for a while with the eyes closed, we may perceive it to be less slanted than at the beginning. After viewing a slanted floor while lying on a flat base, we may perceive it to be more horizontal. We investigated these postural and visual adaptations and their interactions with participants lying and sitting on the floor. The participants were adapted to a floor that was posturally, visually, or jointly slanted, and were asked to estimate the test slants around the adapting slant. The estimates were described as a linear function of the test slant with a high goodness-of-fit over the adapting slant. This supported normalization, not satiation, view. Second, the slope of the function, i.e., sensitivity to slant, in the lying position was low in the postural and visual conditions but high in the joint condition, whereas the sensitivity in the sitting position was equally high in all conditions. This was explained by an increase in visual and non-visual cues to the gravitational vertical in the sitting position, and by an abnormal pattern of intracorporeal hydrostatic pressure in the lying position. Third, in both body positions, the angle at which the slant appeared horizontal, i.e., the subjective horizontal (SH), was larger in the postural condition than in the visual condition. Finally, when the postural and visual adaptations were joint, the SH in the lying position was somewhere between the postural- and visual-alone SHs, whereas the SH in the sitting position approximated the visual-alone SH.

Rigid ureteroscopic lithotripsy in the lateral decubitus position for upper urinary tract stones

Background

The current study aimed to assess a novel ureteroscopic technique developed for treating upper urinary calculi based on a specially designed lateral decubitus body position that could avoid stone loss by adjusting to the effects of gravity.

Methods

This retrospective study examined patients with upper urinary calculi who were surgically treated from November 2008 to January 2020, using a new body position and a rigid ureteroscope. Clinical outcomes, stone-free rates, operative times and complications were evaluated, and factors that could influence treatment success were determined.

Results

In total, 1080 patients were included, and 1145 operations were performed. The maximum calculus diameters were 11.22 ± 5.01 mm. Operative times were 48.60 ± 27.44 min. A total of 1042 cases were successfully treated, with a stone-free rate of 91.00%. Multivariate analysis showed that female sex (OR = 2.135, 95% CI 1.332–3.422, P = 0.002), thin scope standby (OR = 1.643, 95% CI 1.074–2.514, P = 0.022), laser lithotripsy (OR = 5.087, 95% CI 2.400–10.785, P = 0.000) and stone size (OR = 0.946, 95% CI 0.912–0.981, P = 0.003) were independently associated with stone-free outcomes. In total, 2 ureteral perforations, 2 ureteric avulsions and 4 urosepsis cases were observed, but were all cured without sequelae.

Conclusions

Ureteroscopic lithotripsy in the lateral decubitus position is a safe and effective technique for treating upper urinary tract calculi, especially upper ureteral calculi.

Body position for preventing ventilator-associated pneumonia for critically ill patients: a systematic review and network meta-analysis

Background

The evidence about the best body position to prevent ventilator-associated pneumonia (VAP) is unclear. The aim of this study was to know what the best body position is to prevent VAP, shorten the length of intensive care unit (ICU) and hospital stay, and reduce mortality among patients undergoing mechanical ventilation (MV).

Methods

We performed a network meta-analysis of randomized controlled trials including intubated patients undergoing MV and admitted to an ICU. The assessed interventions were different body positions (i.e., lateral, prone, semi-recumbent) or alternative degrees of positioning in mechanically ventilated patients.

Results

Semi-recumbent and prone positions showed a risk reduction of VAP incidence (RR: 0.38, 95% CI: 0.25–0.52) and mortality (RR: 0.70, 95% CI: 0.50–0.91), respectively, compared to the supine position. The ranking probabilities and the surface under the cumulative ranking displayed as the first best option of treatment the semi-recumbent position to reduce the incidence of VAP (71.4%), the hospital length of stay (68.9%), and the duration of MV (67.6%); and the prone position to decrease the mortality (89.3%) and to reduce the ICU length of stay (59.3%).

Conclusions

Cautiously, semi-recumbent seems to be the best position to reduce VAP incidence, hospital length of stay and the duration of MV. Prone is the most effective position to reduce the risk of mortality and the ICU length of stay, but it showed no effect on the VAP incidence.

Registration PROSPERO CRD42021247547

Supplementary Information

The online version contains supplementary material available at 10.1186/s40560-022-00600-z.

The effect of various weight-bearing activities on the motion of lumbar facet joints in vivo

Background

Lumbar facet joints (LFJs) are usually related to the pathogenesis of the spine. The purpose of this paper is to study the effects of lifting load on the motion of lower lumbar facet joints in vivo.

Methods

Ten healthy volunteers aged 25 ≤ 39 years, 5 males and 5 females, were recruited. Using a dual fluoroscopy imaging system (DFIS) combined with CT, firstly, the L3-S1 segment image scanned by CT was converted into a three-dimensional model. Then, the lumbar motion images of L3-S1 vertebrae taken by the DFIS under different loads (0 kg, 5 kg, 10 kg) and different body postures (maximum flexion and extension, maximum left and right bending, and maximum left and right torsion) were captured. Finally, in the Rhino software, the instantaneous motion state of the lumbar spine is reproduced by translation and rotation according to the anatomical structure of the lumbar spine and the previous images. With the help of computer software, a Cartesian coordinate system was placed in the center of each articular surface to measure the kinematics of the articular process and to obtain 6DOF data under different loads (0 kg, 5 kg, 10 kg) in the lumbar facet joints. 

Results

In the flexion and extension of the trunk, weight bearing reduced the translational range in the mid-lateral direction. In the L3/4 segment, the lateral translational range of the left and right facet joints gradually decreased with increasing load, and the translational range at 0 kg was significantly greater than that at 10 kg (left side: 0 kg, 0.86° ± 0.57°, 10 kg, 0.24° ± 0.26°, p = 0.01; right side: 0 kg, 0.86° ± 0.59°, 10 kg, 0.26° ± 0.27°, p = 0.01). In the L5/S1 segment, the translation range of the LFJ at 0 kg was significantly greater than that at 10 kg (p = 0.02). Other bending and rotation movements were not found to cause differential changes in the 6DOF of the LFJ. In bending, the rotation range was the largest in the L3/4 segment (p < 0.05) and gradually decreased from top to bottom. At the same level, there were significant differences in the translation range of the left and right facets in the anterior posterior and craniocaudal directions (p < 0.05).

Conclusion

Increasing the load has a significant impact on the coupled translational movement of lumbar facet joints. The asymmetric translational movement of the left and right facet joints may be a factor that accelerates the degeneration of facet joints.

Body-kun/body-chan style model figures for artists in forensic visualization applications

Posture and body position are often in the focus of forensic medicine. Visualization for the purposes of documentation, teaching, scientific presentation or expert opinion in court is often desired. Plenty of possible tools to support visualization are available. However, there is a significant gap between quick drawings and more complex techniques. Body-chan (female) and body-kun (male) artist's model figurines (genericized trademark) may provide a useful means to fill this gap. These models, about 12-15 cm in height, are multi-articulated humanoids of realistic proportions, intended to serve as models for manga (japanese comic) drawing. Plenty of different models are available in different quality which usually are equipped with interchangeable hand and feet attachments, a frame for 'levitating' positions as well as assorted objects to scale. These inexpensive models may be positioned quickly and intuitively. Photodocumentation from various angles can be performed using a mobile phone camera. Images may be further improved applying digital image manipulation software. Taken together, the process is quick and intuitive and the level of achievable complexity is sufficient for many forensic applications.

Upright versus supine MRI: effects of body position on craniocervical CSF flow

Background

Cerebrospinal fluid (CSF) circulation between the brain and spinal canal, as part of the glymphatic system, provides homeostatic support to brain functions and waste clearance. Recently, it has been observed that CSF flow is strongly driven by cardiovascular brain pulsation, and affected by body orientation. The advancement of MRI has allowed for non-invasive examination of the CSF hydrodynamic properties. However, very few studies have addressed their relationship with body position (e.g., upright versus supine). It is important to understand how CSF hydrodynamics are altered by body position change in a single cardiac phase and how cumulative long hours staying in either upright or supine position can affect craniocervical CSF flow.

Methods

In this study, we investigate the changes in CSF flow at the craniocervical region with flow-sensitive MRI when subjects are moved from upright to supine position. 30 healthy volunteers were imaged in upright and supine positions using an upright MRI. The cranio-caudal and caudo-cranial CSF flow, velocity and stroke volume were measured at the C2 spinal level over one cardiac cycle using phase contrast MRI. Statistical analysis was performed to identify differences in CSF flow properties between the two positions.

Results

CSF stroke volume per cardiac cycle, representing CSF volume oscillating in and out of the cranium, was ~ 57.6% greater in supine (p < 0.0001), due to a ~ 83.8% increase in caudo-cranial CSF peak velocity during diastole (p < 0.0001) and extended systolic phase duration when moving from upright (0.25 ± 0.05 s) to supine (0.34 ± 0.08 s; p < 0.0001). Extrapolation to a 24 h timeframe showed significantly larger total CSF volume exchanged at C2 with 10 h spent supine versus only 5 h (p < 0.0001).

Conclusions

In summary, body position has significant effects on CSF flow in and out of the cranium, with more CSF oscillating in supine compared to upright position. Such difference was driven by an increased caudo-cranial diastolic CSF velocity and an increased systolic phase duration when moving from upright to supine position. Extrapolation to a 24 h timeframe suggests that more time spent in supine position increases total amount of CSF exchange, which may play a beneficial role in waste clearance in the brain.

The effects of a simulated fMRI environment on voice intensity in individuals with Parkinson's disease hypophonia and older healthy adults

PURPOSE

Functional magnetic resonance imaging (fMRI) has promise for understanding neural mechanisms of neurogenic speech and voice disorders. However, performing vocal tasks within the fMRI environment may not always be analogous to performance outside of the scanner. Using a mock MRI scanner, this study examines the effects of a simulated scanning environment on vowel intensity in individuals with Parkinson's disease (PD) and hypophonia and older healthy control (OHC) participants.

METHOD

Thirty participants (15 PD, 15 OHC) performed a sustained /ɑ/ vowel production task in three conditions: 1) Upright, 2) Mock Scanner + No Noise, and 3) Mock Scanner + MRI noise. We used a linear mixed-effects (multi-level) model to evaluate the contributions of group and recording environment to vowel intensity. A second linear mixed-effects model was also used to evaluate the contributions of PD medication state (On vs. Off) to voice intensity.

RESULTS

Vowel intensity was significantly lower for PD compared to the OHC group. The intensity of vowels produced in the Upright condition was significantly lower compared to the Mock Scanner + No Noise condition, while vowel intensity in the Mock Scanner + MRI Noise condition was significantly higher compared to the Mock Scanner + No Noise condition. A group by condition interaction also indicated that the addition of scanner noise had a greater impact on the PD group. A second analysis conducted within the PD group showed no effects of medication state on vowel intensity.

CONCLUSION

Our findings demonstrate that performance on voice production tasks is altered for PD and OHC groups when translated into the fMRI environment, even in the absence of acoustic scanner noise. For fMRI studies of voice in PD hypophonia, careful thought should be given to how the presence of acoustic noise may differentially affect PD and OHC, for both group and task comparisons.

Evaluation of the Impact of Body Position on Primary Central Sleep Apnea Syndrome

OBJECTIVE

To evaluate the impact of the body position on primary central sleep apnea syndrome.

METHODS

Fifty-five subjects diagnosed with central sleep apnea (CSA) through polysomnographic examinations were prospectively enrolled in the study. All patients underwent cardiologic and neurologic examinations. Primary positional central sleep apnea (PCSA) was determined when the supine Apnea-Hypopnea Index (AHI) was greater than two times the non-supine AHI. The primary PCSA and non-PCSA groups were compared in terms of demographic characteristics, sleep parameters, and treatment approaches.

RESULTS

Overall, 39 subjects diagnosed with primary CSA were included in the study; 61.5% of the subjects had primary PCSA. There were no differences between the primary PCSA and non-PCSA groups regarding age, sex, body mass index (BMI), co-morbidities, and history of septoplasty. In terms of polysomnography parameters, AHI (P=.001), oxygen desaturation index (P=.002), the time spent under 88% saturation during sleep (P=.003), number of obstructive apnea (P=.011), mixed apnea (P=.009), and central apnea (P=.007) was lower in the primary PCSA group than in the non-PCSA group. Twenty-nine percent of the patients in the primary PCSA group were recommended position treatment and 71% were recommended positive airway pressure (PAP) therapy; all patients in the non-PCSA group were recommended PAP therapy.

CONCLUSIONS

Our results demonstrated that the rate of primary PCSA was high (61.5%) and primary PCSA was associated with milder disease severity compared with non-PCSA. The classification of patients with primary CSA regarding positional dependency may be helpful in terms of developing clinical approaches and treatment recommendations.

REM sleep without atonia and nocturnal body position in prediagnostic Parkinson's disease

BACKGROUND

Sleep disturbances are features of Parkinson's disease (PD), that can already occur before PD diagnosis. The most investigated prodromal PD sleep disorder is REM sleep behavior disorder (RBD). The relation between other polysomnographic (PSG) alterations and the prediagnostic stages of PD, however, is less clear.

METHODS

We performed a retrospective case-control study to characterize polysomnographic alterations in PD and prediagnostic PD. We included 63 PD subjects (33 subjects that underwent a video-PSG before PD diagnosis [13 with and 20 without RBD] and 30 subjects that underwent a PSG after PD diagnosis) and 30 controls. PSGs were analyzed for sleep stages, different RSWA variables, body position, arousals, periodic limb movements, and REM density.

RESULTS

Higher subscores of all RSWA variables were observed in subjects with PD and prediagnostic PD (with and without RBD). Total RSWA, tonic RSWA and chin RSWA severity were significant predictors for all PD and prediagnostic PD groups. Our study also shows a higher percentage of nocturnal supine body position in all PD and prediagnostic PD groups. Supine body position percentage is the highest in the PD group and has a positive correlation with time since diagnosis.

CONCLUSIONS

These findings suggest that increased total, tonic and chin RSWA as well as nocturnal supine body position are already present in prediagnostic PD, independently of RBD status. Prospective longitudinal studies are necessary to confirm the additional value of these PSG abnormalities as prodromal PD biomarkers.

24-h intraocular pressure patterns measured by Icare PRO rebound in habitual position of open-angle glaucoma eyes

PURPOSE

To measure the 24-h intraocular pressure (IOP) by Icare PRO rebound in healthy and primary open-angle glaucoma (POAG) eyes and compare it with non-contact tonometry (NCT).

METHODS

Thirty POAG patients, who were under IOP-lowering treatment, and 30 healthy subjects were included. Participants were hospitalized overnight for the 24-h IOP measurement. IOPs were measured by Icare PRO and NCT according to a standard protocol every 2 h during 24 h. The 24-h IOP curve and IOP-related parameters were compared between Icare PRO and NCT groups in POAG and healthy eyes.

RESULTS

The IOPs measured by Icare PRO in habitual position increased notably at 22:00 in the normal group and at 20:00 in the POAG group, reached peak at 0:00, stayed high until 4:00, and then decreased in both groups (all p < 0.05). The POAG patients had higher mean 24-h IOP, peak IOP, IOP fluctuation, and greater IOP change from supine to sitting position in the nocturnal period than those in the normal subjects even after adjusting for eyes, age, gender, CCT, and axial length (all p < 0.05).

CONCLUSIONS

The Icare PRO provides a well-tolerated approach for 24-h IOP monitoring in habitual position. Twenty-four-hour IOP in habitual position is more sensitive for detecting high nocturnal IOP peaks and greater IOP fluctuation for POAG patients.

Targeted lateral positioning decreases lung collapse and overdistension in COVID-19-associated ARDS

Background

Among the challenges for personalizing the management of mechanically ventilated patients with coronavirus disease (COVID-19)-associated acute respiratory distress syndrome (ARDS) are the effects of different positive end-expiratory pressure (PEEP) levels and body positions in regional lung mechanics. Right-left lung aeration asymmetry and poorly recruitable lungs with increased recruitability with alternating body position between supine and prone have been reported. However, real-time effects of changing body position and PEEP on regional overdistension and collapse, in individual patients, remain largely unknown and not timely monitored. The aim of this study was to individualize PEEP and body positioning in order to reduce the mechanisms of ventilator-induced lung injury: collapse and overdistension.

Methods

We here report a series of five consecutive mechanically ventilated patients with COVID-19-associated ARDS in which sixteen decremental PEEP titrations were performed in the first days of mechanical ventilation (8 titration pairs: supine position immediately followed by 30° targeted lateral position). The choice of lateral tilt was based on X-Ray. This targeted lateral position strategy was defined by selecting the less aerated lung to be positioned up and the more aerated lung to be positioned down. For each PEEP level, global and regional collapse and overdistension maps and percentages were measured by electrical impedance tomography. Additionally, we present the incidence of lateral asymmetry in a cohort of forty-four patients.

Results

The targeted lateral position strategy resulted in significantly smaller amounts of overdistension and collapse when compared with the supine one: less collapse along the PEEP titration was found within the left lung in targeted lateral (P = 0.014); and less overdistension along the PEEP titration was found within the right lung in targeted lateral (P = 0.005). Regarding collapse within the right lung and overdistension within the left lung: no differences were found for position. In the cohort of forty-four patients, ventilation inequality of > 65/35% was observed in 15% of cases.

Conclusions

Targeted lateral positioning with bedside personalized PEEP provided a selective attenuation of overdistension and collapse in mechanically ventilated patients with COVID-19-associated ARDS and right-left lung aeration/ventilation asymmetry.

Trial registration

Trial registration number: NCT04460859

Lower lung-volume level induces lower vertical center of mass position and alters swimming kinematics during front-crawl swimming

We examined the impact of lung-volume levels on the vertical center of mass (CoM) position and kinematics during submaximal front-crawl swimming at constant velocity. Thirteen well-trained male swimmers (21.2 ± 2.0 years) swam the front-crawl for 15 m at a target velocity of 1.20 m s^-1 while holding one of three lung-volume levels: maximal inspiration (MAX), maximal expiration (MIN), and intermediate between these (MID). The three-dimensional positions of 25 reflective markers attached to each participant's body were recorded using an underwater motion capture system and then used to estimate the body's CoM. The swimming velocity and the vertical CoM position relative to the water's surface were calculated and averaged for one stroke cycle. Stroke rate, stroke length, kick rate, kick amplitude, kick velocity, and trunk inclination were also calculated for one stroke cycle. Swimming velocity was statistically comparable among the three different lung-volume levels (ICC [2,3] = 0.875). The vertical CoM position was significantly decreased with the lower lung-volume level (MAX: -0.152 ± 0.009 m, MID: -0.163 ± 0.009 m, MIN: -0.199 ± 0.007 m, P < 0.001). Stroke rate, kick rate, kick amplitude, kick velocity, and trunk inclination were significantly higher in MIN than in MAX and MID, whereas the stroke length was significantly lower (all P < 0.05). These results indicate that a lower lung-volume level during submaximal front-crawl swimming induces a lower vertical CoM position that is accompanied by a modulation of the swimming kinematics to overcome the increased drag arising from a larger projected frontal area.

Effects of Different Body Positions and Head Elevation Angles on Regional Cerebral Oxygen Saturation in Premature Infants of China

BACKGROUND

To investigate the effects of different body positions and head elevation angles on regional cerebral oxygen saturation in premature infants using near-infrared spectroscopy (NIRS).

METHODS

This was a prospective study of premature infants hospitalized. The position was changed each feeding cycle (2-3 h), in order: 15° prone, 15° supine, 0° prone, and 0° supine position. Regional cerebral oxygen saturation (rSO₂) was measured after each position period using NIRS, over 7 days.

FINDINGS

Thirty-three premature infants were included in the analysis. Among them, 22 (66.7%) were male, and 11 (33.3%) were female. When placing the premature infants in the prone position, the regional cerebral oxygen saturation (rSO₂) values were higher at head elevation 15° compared with 0° (main effect P < 0.001). When placing the premature infants in the supine position, rSO2 was higher at a head elevation of 15° compared with that at 0° (main effect P < 0.001). When placing the premature infants with a head elevation of 15°, rSO2 in the prone position was higher than that of the supine position (main effect P < 0.001). There was no difference between the prone and supine positions when placing the premature infants with the head elevation at 0° (P > 0.05).

DISCUSSION

Higher cerebral rSO2 can be achieved when placing premature infants in the prone or supine position, with a 15° head elevation angle.

APPLICATION TO PRACTICE

Using a specific body position and head angle could improve the regional cerebral oxygen saturation of premature infants.

Feasibility of postural lung recruitment maneuver in children: a randomized, controlled study

BACKGROUND

Pulmonary atelectasis in anesthetized children is easily reverted by lung recruitment maneuvers. However, the high airways pressure reached during the maneuver could negatively affect hemodynamics. The aim of this study is to assess the effect and feasibility of a postural lung recruitment maneuver (P-RM); i.e., a new maneuver that opens up the atelectatic lung areas based on changing the child's body position under constant ventilation with moderated driving pressure (12 cmH₂O) and of positive end-expiratory pressure (PEEP, 10 cmH₂O). Forty ASA I-II children, aged 6 months to 7 years, subjected to general anesthesia were studied. Patients were ventilated with volume control mode using standard settings with 5 cmH₂O of PEEP. They were randomized into two groups: (1) control group (C group, n = 20)-ventilation was turned to pressure control ventilation using a fixed driving pressure of 12 cmH₂O. PEEP was increased from 5 to 10 cmH₂O during 3 min maintaining the supine position. (2) P-RM group (n = 20)-patients received the same increase in driving pressure and PEEP, but they were placed, respectively, in the left lateral position, in the right lateral position (90 s each), and back again into the supine position after 3 min. Then, ventilation returned to baseline settings in volume control mode. Lung ultrasound-derived aeration score and respiratory compliance were assessed before (T1) and after (T2) 10 cmH₂O of PEEP was applied.

RESULTS

At baseline ventilation (T1), both groups showed similar aeration score (P-RM group 9.9 ± 1.9 vs C group 10.4 ± 1.9; p = 0.463) and respiratory compliance (P-RM group 15 ± 6 vs C group 14 ± 6 mL/cmH₂O; p = 0.517). At T2, the aeration score decreased in the P-RM group (1.5 ± 1.6 vs 9.9 ± 2.1; p < 0.001), but remained without changes in the C group (9.9 ± 2.1; p = 0.221). Compliance was higher in the P-RM group (18 ± 6 mL/cmH₂O) when compared with the C group (14 ± 5 mL/cmH₂O; p = 0.001).

CONCLUSION

Lung aeration and compliance improved only in the group in which a posture change strategy was applied.

Evaluation of the Impact of Body Position on Primary Central Sleep Apnea Syndrome

OBJECTIVE

To evaluate the impact of the body position on primary central sleep apnea syndrome.

METHODS

Fifty-five subjects diagnosed with central sleep apnea (CSA) through polysomnographic examinations were prospectively enrolled in the study. All patients underwent cardiologic and neurologic examinations. Primary positional central sleep apnea (PCSA) was determined when the supine Apnea-Hypopnea Index (AHI) was greater than two times the non-supine AHI. The primary PCSA and non-PCSA groups were compared in terms of demographic characteristics, sleep parameters, and treatment approaches.

RESULTS

Overall, 39 subjects diagnosed with primary CSA were included in the study; 61.5% of the subjects had primary PCSA. There were no differences between the primary PCSA and non-PCSA groups regarding age, sex, body mass index (BMI), co-morbidities, and history of septoplasty. In terms of polysomnography parameters, AHI (P=.001), oxygen desaturation index (P=.002), the time spent under 88% saturation during sleep (P=.003), number of obstructive apnea (P=.011), mixed apnea (P=.009), and central apnea (P=.007) was lower in the primary PCSA group than in the non-PCSA group. Twenty-nine percent of the patients in the primary PCSA group were recommended position treatment and 71% were recommended positive airway pressure (PAP) therapy; all patients in the non-PCSA group were recommended PAP therapy.

CONCLUSIONS

Our results demonstrated that the rate of primary PCSA was high (61.5%) and primary PCSA was associated with milder disease severity compared with non-PCSA. The classification of patients with primary CSA regarding positional dependency may be helpful in terms of developing clinical approaches and treatment recommendations.

Using μX-Ray CT to observe postmortem diffusion from the stomach in a rat model

The stomach has long been recognised as a depot for postmortem diffusion. A better understanding of the phenomena of postmortem diffusion would aid forensic practitioners in their interpretation of toxicological results. A limitation of previous stomach diffusion studies was the lack of ability to visualise postmortem diffusion in real time, the use of μX-ray Computed Tomography (CT) could overcome this problem. We utilised CT to track the diffusion of the contrast medium caesium ions (Cs⁺) (administered by oral gavage) from the rat stomach over 6 days. We investigated the influence of temperature (4°C and 20°C) and body position (horizontal and vertical). The results show that the a) diffusion of Cs⁺ from the stomach can be visualised over 6 days, over which a significant amount (∼50%) of the diffusion occurs in the first 24h following administration; b) storing the rat at 4°C reduces the distance of diffusion from the stomach by ∼66%; c) body position influences the route of diffusion and d) in 2 of the 16 rats studied Cs⁺ was found in the right lobe of the liver. Overall these results show that CT using Cs⁺ is a good model to visualise postmortem diffusion and that bodies show significant variation in postmortem diffusion. It is also clear that bodies should be refrigerated and postmortem samples should be taken as soon as possible to minimise the influences of postmortem diffusion from the stomach.

Side lying during nebulisation can significantly improve apical deposition in healthy adults and adults with mild cystic fibrosis lung disease: a randomised crossover trial

Background

In people with and without Cystic Fibrosis (CF), does side lying during nebulisation change: the proportion of the dose loaded in the nebuliser that is deposited in the lungs; the uniformity of deposition throughout the lungs; or the apical drug density as a percentage of the drug density in the remaining lung? Do these effects differ depending on the degree of lung disease present?

Methods

A randomised crossover trial with concealed allocation, intention-to-treat analysis and blinded assessors, involving 39 adults: 13 healthy, 13 with mild CF lung disease (FEV₁ > 80%pred), and 13 with more advanced CF lung disease (FEV₁ < 80%pred). In random order, 4 mL of nebulised radioaerosol was inhaled in upright sitting and in alternate right and left side lying at 2-min intervals, for 20 min.

Results

Compared to sitting upright, lung deposition and the uniformity of deposition were not significantly altered by side lying in any of the three groups. In sitting, the density of the deposition was significantly less in the apical regions than in the rest of the lung in all participants. Side lying significantly improved apical deposition in healthy adults (MD, 13%; 95% CI, 7 to 19), and in minimal CF lung disease (MD, 4%; 95% CI, 1 to 7) but not in advanced disease (MD, 4%; 95% CI, − 2 to 9).

Conclusion

Alternating between right and left side lying during nebulisation significantly improves apical deposition in healthy adults and in adults with mild CF lung disease, without substantial detriment to overall deposition.

Trial registration

ACTRN12611000674932 (Healthy), ACTRN12611000672954 (CF)

Retrospectively registered 4/7/2011.

Electronic supplementary material

The online version of this article (10.1186/s12890-019-0886-7) contains supplementary material, which is available to authorized users.

The effect of body position on airway patency in obstructive sleep apnea: CT imaging analysis

PURPOSE

Positional change during sleep influences upper airway patency. However, few studies have used imaging techniques to demonstrate the change. This study aims to determine the effect of positional change on the upper airway space.

METHODS

A total of 118 subjects with sleep breathing disorders were analyzed. Participants underwent upper airway CT scans in the supine and lateral decubitus positions (right and left). They were divided into non-obstructive sleep apnea (n = 28) and obstructive sleep apnea (n = 90) groups. We measured the minimal cross-sectional area of the retropalatal/retroglossal spaces and compared the differences of those two spaces in the supine and lateral positions. CT was performed while patients were awake.

RESULTS

The minimal cross-sectional area in the OSA group was significantly smaller than non-OSA group in both supine (median[interquartile range], 8.3[0.0-25.1] vs 22.2[1.0-39.6]; P = 0.018) and lateral decubitus positions (5.2[0.0-16.9] vs 21.3[6.1-38.4]; P = 0.002). As the body position of OSA patients shifted from supine to lateral, the retroglossal space increased significantly (67.3[25.1-116.3] vs 93.3[43.4-160.1]; P < 0.001). However, there was no significant difference in the retropalatal space between the supine and lateral decubitus positions.

CONCLUSIONS

Positional change from the supine to lateral decubitus position expands the upper airway lumen, especially the retroglossal space. Positional OSA may be related to anatomical change of the upper airway lumen based on body position.

Slow sinusoidal tilt movements demonstrate the contribution to orthostatic tolerance of cerebrospinal fluid movement to and from the spinal dural space

Standing up elicits a host of cardiovascular changes which all affect the cerebral circulation. Lowered mean arterial blood pressure (ABP) at brain level, change in the cerebral venous outflow path, lowered end-tidal PCO2 (PET CO2 ), and intracranial pressure (ICP) modify cerebral blood flow (CBF). The question we undertook to answer is whether gravity-induced blood pressure (BP) changes are compensated in CBF with the same dynamics as are spontaneous or induced ABP changes in a stable position. Twenty-two healthy subjects (18/4 m/f, 40 ± 8 years) were subjected to 30° and 70° head-up tilt (HUT) and sinusoidal tilts (SinTilt, 0°↨60° around 30° at 2.5-10 tilts/min). Additionally, at those three tilt levels, they performed paced breathing at 6-15 breaths/min to induce larger than spontaneous cardiovascular oscillations. We measured continuous finger BP and cerebral blood flow velocity (CBFv) in the middle cerebral artery by transcranial Doppler to compute transfer functions (TFs) from ABP- to CBFv oscillations. SinTilt induces the largest ABP oscillations at brain level with CBFv gains strikingly lower than for paced breathing or spontaneous variations. This would imply better autoregulation for dynamic gravitational changes. We demonstrate in a mathematical model that this difference is explained by ICP changes due to movement of cerebrospinal fluid (CSF) into and out of the spinal dural sack. Dynamic cerebrovascular autoregulation seems insensitive to how BP oscillations originate if the effect of ICP is factored in. CSF-movement in-and-out of the spinal dural space contributes importantly to orthostatic tolerance by its effect on cerebral perfusion pressure.

Differences in body positional bilateral symmetry between stance and supine positions, and the impact of attention and awareness on postural symmetry

BACKGROUND AND PURPOSE

Postural asymmetries may cause structural pathological conditions and impaired movement pattern. The influence of body position and awareness towards symmetry has not yet been elucidated. The aim of this study was twofold: First, to compare the body positional bilateral symmetry between standing and supine positions, and second, to examine whether the awareness to symmetry can modify posture perception and body positional bilateral symmetry.

METHODS

We analyzed the degree of anterior postural alignment symmetry of 34 healthy subjects by photogrammetric method (three photographs in a standing position and three in a supine position). Each photo captured different state of awareness: Subjective Comfortable Posture (SCP), Subjective Perceived Symmetrical Posture (SPSP), and Guided Posture Protocol (GPP).

RESULTS

The standing position increased the symmetrical alignment of the neck (p < 0.013) and the upper limbs (p < 0.011). However, the supine position demonstrated increased symmetrical alignment of the upper trunk (p < 0.019) and the feet (p < 0.002). In the standing position, GPP showed greater symmetry of the neck (p < 0.022), the shoulders (p < 0.014), the thorax midline (p < 0.009), the upper trunk (p < 0.000) and the upper limbs (p < 0.029). No significant changes were observed in the supine position between the three states of awareness.

CONCLUSIONS

Study results indicate that the supine position shows greater degree of upper trunk's symmetrical alignment than the standing position. It also indicates that while standing, focusing attention into symmetry improves body positional bilateral symmetry. These results might have clinical implications when working with patients who suffer from asymmetric posture.

Effects of postmortem positional changes on conjunctival petechiae

The present study aimed to determine whether postmortem period, physical constitution, cause of death, and cardiopulmonary resuscitation are associated with positional changes in the postmortem appearance of conjunctival petechiae. We retrospectively investigated serial forensic autopsies from 6 h to 6 days postmortem (n = 442; male, 303; female, 139; median age, 62 years; range, 0–100 years). The causes of death were sharp instrument injury, blunt force trauma, fire, intoxication, asphyxia, drowning, hypothermia, hyperthermia, acute heart failure, and natural causes. Of these, 28 (male, n = 18; female, n = 10) were aged ≤5 years. Palpebral conjunctival petechiae were initially assessed at autopsy in supine bodies, then reassessed in prone bodies after 30 min. Among 414 bodies, 291 (70.2%) and 123 (29.7%) who were aged between 6 and 100 years, and 18 (64.2%) and 10 (35.7%) aged <5 years at the time of death, were discovered in the supine and prone positions, respectively. The amounts of petechiae increased within 1.5 days postmortem, but not in those discovered in the prone position. The rates at which petechiae increased were higher in supine overweight bodies (BMI ≥ 25.0) and in those who were discovered supine and had died of asphyxia or drowning (37.5%). Cardiopulmonary resuscitation for bodies discovered in the supine and prone positions did not statistically affect the occurrence of petechiae. Several postmortem factors can cause hypostatic blood redistribution that manifests as increased amounts of petechiae in the palpebral conjunctivae.

The effect of body position on pulmonary function: a systematic review

BACKGROUND

Pulmonary function tests (PFTs) are routinely performed in the upright position due to measurement devices and patient comfort. This systematic review investigated the influence of body position on lung function in healthy persons and specific patient groups.

METHODS

A search to identify English-language papers published from 1/1998-12/2017 was conducted using MEDLINE and Google Scholar with key words: body position, lung function, lung mechanics, lung volume, position change, positioning, posture, pulmonary function testing, sitting, standing, supine, ventilation, and ventilatory change. Studies that were quasi-experimental, pre-post intervention; compared ≥2 positions, including sitting or standing; and assessed lung function in non-mechanically ventilated subjects aged ≥18 years were included. Primary outcome measures were forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC, FEV1/FVC), vital capacity (VC), functional residual capacity (FRC), maximal expiratory pressure (PEmax), maximal inspiratory pressure (PImax), peak expiratory flow (PEF), total lung capacity (TLC), residual volume (RV), and diffusing capacity of the lungs for carbon monoxide (DLCO). Standing, sitting, supine, and right- and left-side lying positions were studied.

RESULTS

Forty-three studies met inclusion criteria. The study populations included healthy subjects (29 studies), lung disease (nine), heart disease (four), spinal cord injury (SCI, seven), neuromuscular diseases (three), and obesity (four). In most studies involving healthy subjects or patients with lung, heart, neuromuscular disease, or obesity, FEV1, FVC, FRC, PEmax, PImax, and/or PEF values were higher in more erect positions. For subjects with tetraplegic SCI, FVC and FEV1 were higher in supine vs. sitting. In healthy subjects, DLCO was higher in the supine vs. sitting, and in sitting vs. side-lying positions. In patients with chronic heart failure, the effect of position on DLCO varied.

CONCLUSIONS

Body position influences the results of PFTs, but the optimal position and magnitude of the benefit varies between study populations. PFTs are routinely performed in the sitting position. We recommend the supine position should be considered in addition to sitting for PFTs in patients with SCI and neuromuscular disease. When treating patients with heart, lung, SCI, neuromuscular disease, or obesity, one should take into consideration that pulmonary physiology and function are influenced by body position.

Effects of patient positioning on respiratory mechanics in mechanically ventilated ICU patients

Changes in the body position of patients receiving mechanical ventilation in intensive care unit are frequent. Contrary to healthy humans, little data has explored the physiological impact of position on respiratory mechanics. The objective of present paper is to review the available data on the effect of changing body position on respiratory mechanics in ICU patients receiving mechanical ventilation. Supine position (lying flat) or lateral position do not seem beneficial for critically ill patients in terms of respiratory mechanics. The sitting position (with thorax angulation >30° from the horizontal plane) is associated with improvement of functional residual capacity (FRC), oxygenation and reduction of work of breathing. There is a critical angle of inclination in the seated position above which the increase in abdominal pressure contributes to increase chest wall elastance and offset the increase in FRC. The impact of prone position on respiratory mechanics is complex, but the increase in chest wall elastance is a central mechanism. To sum up, both sitting and prone positions provides beneficial impact on respiratory mechanics of mechanically ventilated patients as compared to supine position.

Influence of upright versus time trial cycling position on determination of critical power and W' in trained cyclists

Body position is known to alter power production and affect cycling performance. The aim of this study was to compare mechanical power output in two riding positions, and to calculate the effects on critical power (CP) and W' estimates. Seven trained cyclists completed three peak power output efforts and three fixed-duration trial (3-, 5- and 12-min) riding with their hands on the brake lever hoods (BLH), or in a time trial position (TTP). A repeated-measures analysis of variance showed that mean power output during the 5-min trial was significantly different between BLH and TTP positions, resulting in a significantly lower estimate of CP, but not W', for the TTP trial. In addition, TTP decreased the performance during each trial and increased the percentage difference between BLH and TTP with greater trial duration. There were no differences in pedal cadence or heart rate during the 3-min trial; however, TTP results for the 12-min trial showed a significant fall in pedal cadence and a significant rise in heart rate. The findings suggest that cycling position affects power output and influences consequent CP values. Therefore, cyclists and coaches should consider the cycling position used when calculating CP.

Modelling the effect of gravity on inert-gas washout outputs

Multiple-breath washout (MBW) is a pulmonary function test (PFT) that is used to infer lung function through measurement of ventilation heterogeneity (VH). However, the body position that a test is taken in may also influence VH, due to the "Slinky" effect of gravity on the lungs. In healthy subjects this has minimal effect, but in unhealthy groups, PFT outputs have been seen to change drastically with body position. In this study, we used a combined computational and clinical approach to better understand the response of outputs from the MBW to body position. A patient-specific model of the MBW was developed, then validated against clinically measured washout data, as well as broader results in the literature. This model was then used to compare changes in MBW outputs with respect to body position, showing that output changes sensitively predict regional airway size differences between lobes. We then highlight cases in which body position effects may bias MBW outputs, leading to elevated or masked responses to bronchoconstriction. We close by placing this result in context with broader clinical practice, and showing how it can help improve interpretation of test outputs.

Positional effects on the distributions of ventilation and end-expiratory gas volume in the asymmetric chest-a quantitative lung computed tomographic analysis

Background

Body positioning affects the configuration and dynamic properties of the chest wall and therefore may influence decisions made to increase or decrease ventilating pressures and tidal volume. We hypothesized that unlike global functional residual capacity (FRC), component sector gas volumes and their corresponding regional tidal expansions would vary markedly in the setting of unilateral pleural effusion (PLEF), owing to shifting distributions of aeration and collapse as posture changed.

Methods

Six deeply anesthetized swine underwent tracheostomy, thoracostomy, and experimental PLEF with 10 mL/kg of radiopaque isotonic fluid randomly instilled into either pleural space. Animals were ventilated at V_T = 10 mL/kg, frequency = 15 bpm, I/E = 1:2, PEEP = 1 cmH₂O, and FiO₂ = 0.5. Quantitative lung computed tomographic (CT) analysis of regional aeration and global FRC measurements by nitrogen wash-in/wash-out technique was performed in each of these randomly applied positions: semi-Fowler’s (inclined 30° from horizontal in the sagittal plane); prone, supine, and lateral positions with dependent PLEF and non-dependent PLEF.

Results

No significant differences in total FRC were observed among the horizontal positions, either at baseline (p = 0.9037) or with PLEF (p = 0.58). However, component sector total gas volumes in each phase of the tidal cycle were different within all studied positions with and without PLEF (p = < .01). Compared to other positions, prone and lateral positions with non-dependent PLEF had more homogenous V_T distributions among quadrants (p = .051). Supine position was associated with most dependent collapse and greatest tendency for tidal recruitment (48 vs ~ 22%, p = 0.0073).

Conclusions

Changes in body position in the setting of effusion-caused chest asymmetry markedly affected the internal distributions of gas volume, collapse, ventilation, and tidal recruitment, even though global FRC measurements provided little indication of these potentially important positional changes.

Electronic supplementary material

The online version of this article (10.1186/s40635-018-0175-4) contains supplementary material, which is available to authorized users.

The use of an alternate side lying positioning strategy during inhalation therapy does not prolong nebulisation time in adults with Cystic Fibrosis: a randomised crossover trial

BACKGROUND

Inhalation of nebulised medications is performed in upright sitting to maximise lung volumes. The pattern of deposition is poor for inhaled medications in people with Cystic Fibrosis. The pattern tends to be non-uniform and typically the upper lobes receive a reduced dose compared to the rest of the lung. One strategy that has been proposed as having the potential to improve homogeneity of deposition is to adopt an alternate side lying position for the inhalation procedure. This study sought to determine whether, among adults with Cystic Fibrosis, there is any disadvantage to delivery time of nebulised medications with a strategy of alternate side lying, compared to upright sitting.

METHODS

A randomised crossover trial with concealed allocation, intention-to-treat analysis and blinded assessors was undertaken. The participants were 24 adults with stable Cystic Fibrosis. They inhaled 4 mL of normal saline via an LC Star™ nebuliser twice within 24 h. In random order, participants sat upright throughout nebulisation, or alternated between left and right side lying at each minute during the nebulisation period. The nebuliser was stopped and weighed each minute until the residual volume was reached. The primary outcome was the time required for 3.5 mL to be delivered. The secondary outcomes were: respiratory rate; ratio of the volume delivered on right and left sides; and calculation of how long the periods in side lying can be extended without causing greater than 20% discrepancy in dose delivered in the two positions.

RESULTS

The delivery time did not significantly differ between sitting and side lying (mean difference 0.58 min, 95% confidence interval (CI) -1.40 to 0.24). There was no significant correlation between delivery time, lung function or subject height (all R² < 0.4). Increasing side lying duration from 1 to 2 min did not significantly impact the dose delivered on each side. Turning each 3 min however, significantly worsened the disparity (mean ratio 1.32, 95% CI 1.24 to 1.40).

CONCLUSION

Side lying during inhalation therapy does not prolong nebulisation time. 2-min periods should provide an equal dose in the two side lying positions.

TRIAL REGISTRATION

Prospectively registered on 4 July 2011; ACTRN12611000672954 .

Normal Values of High-Resolution Manometry in Supine and Upright Positions in a Thai Population

BACKGROUND

Although cut-off values used in high-resolution manometry (HRM) to diagnose esophageal motility disorders are based on representative samples of the US population and assume a supine position, differences in population and body positioning can reportedly affect results.

AIMS

To establish normal HRM values for Thai people in both supine and upright positions.

METHODS

Forty-one healthy subjects were recruited, each of whom underwent solid-state HRM with ten 5-mL swallows of water in both the supine and upright positions. Measuring parameters according to the Chicago classification criteria (CC v3.0) were included, for which the mean, median and 5th and 95th percentiles (PCTLs) were calculated.

RESULTS

The results corresponded with the CC v3.0 criteria, except for the mean, and 5th PCTL of the distal contractile integral (DCI), which were lower for this population. In the upright position, the mean and median values for DCI, intrabolus pressure and integrated relaxation pressure were significantly decreased, whereas the length of the transitional zone was significantly increased. The limitations of this study include: (1) the relatively low number of participants, (2) the limited recruitment of participants only at Ramathibodi Hospital and (3) the limited recruitment of only young and middle-aged participants.

CONCLUSIONS

We established normal values for the HRM parameters in a representative sample of the Thai population. Our supine results still prove that the use of the CC v3.0 is preferable. HRM testing in patients measured in the upright position should be analyzed based on the normative values obtained from upright swallow studies.

Short-term blood pressure variability - variation between arm side, body position and successive measurements: a population-based cohort study

Background

Precise blood pressure (BP) measurements are central for the diagnosis of hypertension in clinical and epidemiological studies. The purpose of this study was to quantify the variability in BP associated with arm side, body position, and successive measurements in the setting of a population-based observational study. Additionally, we aimed to evaluate the influence of different measurement conditions on prevalence of hypertension.

Methods

The sample included 967 men and 812 women aged 45 to 83 years at baseline. BP was measured according to a standardized protocol with oscillometric devices including three sitting measurements at left arm, one simultaneous supine measurement at both arms, and four supine measurements at the arm with the higher BP. Hypertension was defined as systolic BP (SBP) ≥140 mmHg and/or diastolic BP (DBP) ≥90 mmHg. Variability in SBP and DBP were analysed with sex-stratified linear covariance pattern models.

Results

We found that overall, no mean BP differences were measured according to arm-side, but substantial higher DBP and for men also higher SBP was observed in sitting than in supine position and there was a clear BP decline by consecutive measurement. Accordingly, the prevalence of hypertension depends strongly on the number and scheme of BP measurements taken to calculate the index values.

Conclusions

Thus, BP measurements should only be compared between studies applying equal measurement conditions and index calculation. Moreover, the first BP measurement should not be used to define hypertension since it overestimates BP. The mean of second and third measurement offers the advantage of better reproducibility over single measurements.

Electronic supplementary material

The online version of this article (doi:10.1186/s12872-017-0468-7) contains supplementary material, which is available to authorized users.

Gunshot wound trajectory analysis using forensic animation to establish relative positions of shooter and victim

Forensic pathologists who autopsy the victims of gun violence are often called upon to answer questions in both criminal and civil proceedings about the relative position of the shooter and the victim. In this case report of an officer-involved shooting incident, the statement of the police officer appeared to be in direct contradiction to the statements of other eyewitnesses, the evidence at the scene, and the final resting position of the decedent's body. Trajectory analysis of two gunshot wound pathways (only one of which was instantaneously incapacitating) was performed to assess the veracity of the officer's statement and forensic animation was used to create a court exhibit. A discussion of the current peer-reviewed literature is included.

Abdominal muscle activity during breathing in different postures in COPD "Stage 0" and healthy subjects

This study aims to evaluate the effect of different postures on the abdominal muscle activity during breathing in subjects "at risk" for the development of chronic obstructive pulmonary disease (COPD) and healthy. Twenty-nine volunteers, divided in "At Risk" for COPD (n=16; 47.38±5.08years) and Healthy (n=13; 47.54±6.65years) groups, breathed at the same rhythm in supine, standing, tripod and 4-point-kneeling positions. Surface electromyography was performed to assess the activation intensity of rectus abdominis, external oblique and transversus abdominis/internal oblique (TrA/IO) muscles, during inspiration and expiration. From supine to standing, an increased activation of all abdominal muscles was observed in "At Risk" for COPD group; however, in Healthy group, TrA/IO muscle showed an increased activation. In both groups, the TrA/IO muscle activation in tripod and 4-point kneeling positions was higher than in supine and lower than in standing. Subjects "at risk" for the development of COPD seemed to have a specific recruitment of the superficial layer of ventrolateral abdominal wall for the synchronization of postural function and mechanics of breathing.

The effect of positional changes on oxygenation in patients with head injury in the intensive care unit

Background:

Following head injury, cardiopulmonary functions are impaired and this disturbs the oxygenation transport pathway. Expanding cardiopulmonary physical therapy to encompass the oxygen transport system as a whole has implication for treatment as well as assessment and treatment outcome. Therefore, the aim of the study is to assess the oxygenation level in head injury patients with relation to body positioning in the intensive care unit (ICU).

Methodology:

Thirty consecutive patients with head injury with hemodynamically stable were included from the surgical ICU, ages ranging from 15 to 50 years. Noninvasive vital parameters (oxygen saturation [SpO₂], pulse rate [PR], respiratory rate [RR], and blood pressure [BP]) were observed and recorded in different body positions at regular intervals of 5 min for 15 min in each position.

Results:

There was increment in SpO₂ value in all positions from 0 min to end of 15 min in supine (98.63 ± 0.36–98.73 ± 0.30), right-side lying (98.77 ± 0.30–98.93 ± 0.20), left-side lying (98.73 ± 0.29–99.03 ± 0.24), and recline sitting (30°–70°) (99.03 ± 0.24–99.50 ± 0.22). However, there was statistically significant increment in recline sitting (30°–70°) compared to other positions (P = 0.036) while other parameters (PR, RR, and BP) were getting stabilized at lower values at end of 15 min in every positions tested.

Conclusion:

We conclude that upright position bring about significant increase in arterial SpO₂ compared to any other positions. Other vital parameters were seen to stabilize at lower values at the end of 15 min in every position tested.

The Effect of Patient Positioning on Amount of Intraoperative Bleeding in Rhinoplasty: A Randomized Controlled Trial

BACKGROUND

There is a rich blood flow to the mucosa in the nasal region. In rhinoplasty, surgical procedures are performed in a narrow and confined space. So bleeding during surgery reduces visibility which can complicate the procedure. This study investigated the effects of the patient position on amount of intraoperative bleeding during surgical procedures.

PATIENTS AND METHODS

This randomized controlled trial was conducted on 71 patients who underwent elective rhinoplasty. The patients were operated on in three groups. Group 1 consisted of 23 patients who were operated on in the supine position; Group 2 included 28 patients who were operated on using a 15° angle reverse Trendelenburg position; Group 3 consisted of 20 patients who were operated on at a 20° angle reverse Trendelenburg position.

RESULTS

There were statistically significant differences between the groups in regard to surgeon satisfaction and the amount of intraoperative bleeding. The amount of intraoperative bleeding in Group 1 was significantly higher than those of Groups 2 and 3, and surgeon satisfaction was lower.

CONCLUSIONS

Reverse Trendelenburg position reduces intraoperative bleeding in rhinoplasty patients while facilitating the procedure compared to the supine position. Surgery at a 15° angle reverse Trendelenburg position provides the optimum working conditions by both significantly reducing intraoperative bleeding and allowing for comfortable conditions for the surgeon.

LEVEL OF EVIDENCE I

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

The Effect of Body Position on Intraocular and Intracranial Pressure in Rabbits

BACKGROUND

The correlation between cerebrospinal fluid (CSF) and intraocular pressure (IOP) is still unclear. We compared CSF and IOP measured by the same invasive technique using a new experimental model in rabbits during changes of body position.

METHODS

Pressure changes were recorded in the lateral ventricle (LV), the cortical subarachnoid space (CSS), and the anterior ocular chamber of anesthetized rabbits (n = 12). Animals and measuring instruments were both fixed on a board at an adequate hydrostatic level.

RESULTS

In a horizontal position, control IOP (15.1 ± 1.6 cmH2O) and CSF pressure in the LV (12.4 ± 0.6 cmH2O) and CSS (12.2 ± 0.9 cmH2O) were similar during the 60-min period. When changing the body position from horizontal to vertical (upright), CSF pressures decreased drastically (LV = -5.5 ± 2.6 cmH2O and CSS = -7.7 ± 2.3 cmH2O), while the IOP decreased moderately (IOP = 13.3 ± 0.5 cmH2O).

CONCLUSION

Change in body position from horizontal to vertical causes drastic changes in CSF pressure and moderate changes in IOP. Thus, IOP is not reflected by the CSF pressure. In an upright position, the values of CSF pressure were equal to the hydrostatic distance between measuring points and the foramen magnum, which suggests that CSF pressure inside the cranium depends on its anatomical and biophysical features, and not on CSF secretion and absorption.

The effect of body posture during medication inhalation on exercise induced bronchoconstriction in asthmatic children

RATIONALE

Inhaling medication in a standard body posture leads to impaction of particles in the sharp angle of the upper airway. Stretching the upper airway by extending the neck in a forward leaning body posture may improve pulmonary deposition. A single dose of inhaled corticosteroids (ICS) offers acute, but moderate protection against exercise induced bronchoconstriction (EIB). This study investigated whether inhaling a single dose of ICS in a forward leaning posture improves this protection against EIB.

METHODS

32 Asthmatic children, 5-16 years, with EIB (Median fall in FEV1 or FEV0.5 30.9%) performed two exercise challenge tests (ECT's) with spirometry in a single blinded cross-over trial design. Children inhaled a single dose of 200 μg beclomethasone dipropionate (BDP) 4 h before the ECT, once in the standard posture and once with the neck extended in a forward leaning posture. Spirometry was also performed before the inhalation of the single dose of BDP.

RESULTS

Inhalation of BDP in both body postures provided similar protection against EIB (fall in FEV1 or FEV0.1 in standard posture 16.7%; in forward leaning posture 15.1%, p = 0.83). Inhaling ICS in a forward leaning posture significantly delayed EIB compared to inhaling in the standard posture (respectively 2.5 min ± 1.0 min vs. 1.6 min ± 0.8 min; difference 0.9 min (95CI 0.25; 1.44 min); p = 0.01).

CONCLUSION

Inhalation of a single dose BDP in both the forward leaning posture and the standard posture provided effective and similar protection against EIB in asthmatic children, but the forward leaning posture resulted in a delay of EIB.

REGISTER

NTR3432 (www.trialregister.nl).