Effect of Different Positions on FVC and FEV1 Measurements of Asthmatic Patients

Mechanisms relating to sleeping position to the endotypes of sleep disordered breathing

PURPOSE

Obstructive sleep apnea (OSA) severity varies considerably depending on the body position during sleep in certain subjects. Such variability may be underpinned by specific, body position-related changes in OSA pathophysiological determinants, or endotypes. Also head position relative to trunk may influence OSA endotypes. However, no studies to our knowledge have reviewed the endotype variations according to head or body position up to now.

RECENT FINDINGS

Several findings illustrate that supine OSA is mostly attributable to unfavorable upper airway anatomy compared to lateral position. However, a reduced lung volume, with consequent ventilatory instability (or elevated loop gain), may also play a role. Furthermore, preliminary findings suggest that prone and reclined positions may have a beneficial effect on collapsibility and loop gain.

SUMMARY

Sleeping supine induces many unfavorable pathophysiological changes, especially in certain predisposed OSA patients. Little is known on the influence of other sleep positions on key endotypic traits.

Body landmarks and genetic algorithm-based approach for non-contact detection of head forward posture among Chinese adolescents: revitalizing machine learning in medicine

Addressing the current complexities, costs, and adherence issues in the detection of forward head posture (FHP), our study conducted an exhaustive epidemiologic investigation, incorporating a comprehensive posture screening process for each participant in China. This research introduces an avant-garde, machine learning-based non-contact method for the accurate discernment of FHP. Our approach elevates detection accuracy by leveraging body landmarks identified from human images, followed by the application of a genetic algorithm for precise feature identification and posture estimation. Observational data corroborates the superior efficacy of the Extra Tree Classifier technique in FHP detection, attaining an accuracy of 82.4%, a specificity of 85.5%, and a positive predictive value of 90.2%. Our model affords a rapid, effective solution for FHP identification, spotlighting the transformative potential of the convergence of feature point recognition and genetic algorithms in non-contact posture detection. The expansive potential and paramount importance of these applications in this niche field are therefore underscored.

Difference in the airway luminal area between the standing and supine positions using upright and conventional computed tomography

No clinical studies to date have compared the airway luminal area between supine and standing positions. Our aim was therefore to compare the airway luminal area between these two positions on computed tomography (CT) and to determine its correlation with forced expiratory volume in 1 s (FEV1). Thirty-two asymptomatic volunteers underwent both conventional (supine position) and upright (standing position) CT during deep inspiration breath-holding. Pulmonary function tests were conducted on the same day. We measured the airway luminal area on CT in each position. Paired t-tests and Pearson's correlation coefficients were used for statistical analysis. The average luminal areas of the trachea, right and left main bronchi, and average third-generation airway were greater in the standing than the supine position by 3.4%, 6.1%, 5.5%, and 5.2%, respectively. The correlation coefficients between airway luminal areas and FEV1 tended to be higher in the standing than the supine position; this correlation was highest for the average third-generation airway (r = 0.70, P < 0.0001). The airway luminal areas of the trachea, bilateral main bronchi, and average third-generation airway were greater in the standing than the supine position. The average third-generation airway area in the standing position had the highest correlation with FEV1.

Influence of phase of respiratory cycle on ultrasound imaging of deep abdominal muscle thickness

BACKGROUND

It is difficult to evaluate the transversus abdominis (TrA) and internal oblique (IO) due to their dual role in both trunk control and breathing.

OBJECTIVES

To investigate whether TrA and IO thickness as measured by ultrasound differs across the respiratory cycle in upright standing.

DESIGN

Observational study.

METHODS

Thickness of TrA and IO was measured with ultrasound in 67 subjects in upright standing. Measures were performed 3 times and by 2 assessors, at the end of relaxed expiration, at the end of a full inspiration, and at the end of full expiration. Differences were assessed by ANOVA. Intra- and inter-rater reliability (of a single measure and the average of 3 measures) were assessed by intra-class correlation (ICC).

RESULTS

Thickness of the TrA and IO was higher at full expiration than at the end of relaxed expiration (p < 0.001), and in turn compared to at full inspiration (p < 0.001). Intra-rater reliability was excellent at all respiratory phases (ICC 0.76-0.87). Whereas inter-rater reliability for a single measure was only fair to good for TrA (ICC 0.52-0.71) and good to excellent for IO (ICC 0.61-0.78), the inter-rater reliability of the average was excellent at all respiratory phases (ICC 0.75-0.90).

CONCLUSIONS

Thickness of TrA and IO increases when lung volume decreases. The intra- and inter-rater reliability of an average measure were excellent at the end of relaxed expiration, full inspiration and full expiration. This provides new opportunities to evaluate the deep abdominal muscles, and their role in respiration, in a physiotherapeutic setting.

The Correlation Between Asthma Severity and Neutrophil to Lymphocyte Ratio

Background—The prognosis is essential in management and follows up of asthmatic patients. Neutrophil to lymphocyte ratio is considered as the common prognostic marker for many diseases especially the asthma. Aim of study—To assess the relationship between asthma severity and neutrophil to lymphocyte ratio in comparison to healthy controls. Patients and methods—This study is a cross sectional study conducted in Respiratory Consultancy Clinic in Baghdad Teaching Hospital in Medical City during the period from 1st of October, 2018 to 31st of March, 2019 on sample of 50 asthmatic patients and 50 healthy controls. The diagnosis of asthma was confirmed by the supervisor through clinical symptoms, signs, spirometery with reversibility test (according to GINA guideline.). Results—A highly significant difference was observed between asthmatic cases and controls regarding age (p<0.001). A significant association was observed between obesity and asthmatic cases (p=0.001). There was a highly significant association between high neutrophil/lymphocyte ratio and asthmatic cases (p<0.001). The neutrophil/lymphocyte ratio was significantly increased with advanced age, females, severe and uncontrolled asthma. Conclusions—The neutrophil to lymphocyte ratio is useful biomarker in assessment of asthma severity.

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.

Effect of Different Head-Neck Postures on the Respiratory Function in Healthy Males

Normal respiration is a very intricate function that comprises mechanical as well as nonmechanical components. It is shown to be affected by various factors including age, lifestyle, disease, and change in posture. With the increased use of hand held devices, everyone is prone to poor sitting postures like forward head posture. The purpose of this study was to evaluate the effect of assumed forward head posture and torticollis on the diaphragm muscle strength. A sample of 15 healthy males, aged 18-35 years, was recruited for this study. All subjects performed spirometry to measure the forced expiratory volume in 1 second (FEV₁), the forced vital capacity (FVC), and FEV₁/FVC ratio. SNIP was measured during upright sitting, induced forward head posture, and torticollis. Subject's mean age (SD) was 23(6) years. The SNIP score of the subjects during sitting with FHP was lower as compared to that during upright sitting. It decreased significantly during induced right torticollis position. This is the first study exploring the impact of different head and neck positions on respiratory function. Alteration of head and neck positions had an immediate negative impact on respiratory function. Clinicians should be prompted to assess respiratory function when assessing individuals with mal-posture.

Effect of Upright and Slouched Sitting Postures on the Respiratory Muscle Strength in Healthy Young Males

Objective

The present study compared the effects of upright and slouched sitting postures on the respiratory muscle strength in healthy young males.

Methods

A total of 35 adult male subjects aged 18–35 years participated in this study. Respiratory muscle strength was determined by measurement of sniff nasal inspiratory pressure (SNIP) using a MicroRPM device in the upright and slouched sitting positions. The subjects were asked to perform the pulmonary function test including peak expiratory flow (PEF), forced expiratory volume in one second (FEV₁), forced vital capacity (FVC), and FEV₁/FVC ratio at baseline. Body composition was also determined.

Results

There was a significant difference of SNIP score between upright sitting and slouched sitting positions (p = 0.04). The mean difference of SNIP score between upright sitting and slouched sitting positions was 8.7 cmH₂O. Significant correlations were found between SNIP in upright sitting and FEV₁% predicted values [R = .651], SNIP in slouched sitting and FEV₁% predicted values [R = .579], and SNIP in upright sitting and SNIP in slouched sitting positions [R = .926] (p < 0.05 for all). There were no significant correlations between SNIP scores, demographic variables, and other baseline clinical data (p > 0.05).

Conclusions

The slouched sitting position had a lower SNIP score compared to upright sitting position suggesting a reduced diaphragm tension and movement as a result of altered body posture.

Effect of Recumbent Body Positions on Dynamic Lung Function Parameters in Healthy Young Subjects

INTRODUCTION

The change in body position can alter pulmonary functions parameters, therefore it is important to understand the physiological basis of these alteration. Ideally, spirometry is done in sitting position until the subject is unable to do so. Hospitalized patients often assume recumbent body positions irrespective of underlying pathology. Hence, need arises to find out best recumbent body positions for the benefit of these patients to make breathing comfortable for them.

AIM

The aim of this study was to find out whether the change from the supine position to crook lying and Fowler's position (45° dorsal elevation) causes change in spirometric parameters.

MATERIALS AND METHODS

The present work was carried out at Department of Physiology, King George's Medical University, Lucknow. A total 131 apparently healthy individuals were enrolled in this cross-sectional study. Lung function was assessed using a PC-based spirometer according to American Thoracic Society guideline in the supine, crook lying and Fowler's position (45° dorsal elevation).

RESULTS

The study consisted of 131 subjects (male 66%, female 34%), with mean age of 20.15±2.71 years and BMI 21.20±3.28 Kg/m². Repeated measures ANOVA with post hoc Bonferroni test was used to compare the mean values between each body position. Compared with the other two positions, Fowler's position showed significantly (p<0.05) higher values for FVC, FEV₁, PEF, FEF_25-75%.

CONCLUSION

Recumbent body position influences spirometric parameters in young healthy subjects. We demonstrated that spirometric values are higher in the Fowler's position than in the supine or crook lying position. The results of this study will help in the selection of the best alternative position for the spirometry in bed ridden patients.

The physiological basis and clinical significance of lung volume measurements

From a physiological standpoint, the lung volumes are either dynamic or static. Both subclasses are measured at different degrees of inspiration or expiration; however, dynamic lung volumes are characteristically dependent on the rate of air flow. The static lung volumes/capacities are further subdivided into four standard volumes (tidal, inspiratory reserve, expiratory reserve, and residual volumes) and four standard capacities (inspiratory, functional residual, vital and total lung capacities). The dynamic lung volumes are mostly derived from vital capacity. While dynamic lung volumes are essential for diagnosis and follow up of obstructive lung diseases, static lung volumes are equally important for evaluation of obstructive as well as restrictive ventilatory defects. This review intends to update the reader with the physiological basis, clinical significance and interpretative approaches of the standard static lung volumes and capacities.