Search results for "Supine position"
showing 10 items of 91 documents
Effect of head position on refraction in aphakic and phakic silicone-filled eyes.
1997
BACKGROUND The refraction of the eye is altered significantly after the instillation of silicone oil into the vitreous cavity because of the silicone oil's high refractive index. The degree of the refractive change shows diurnal variation and depends on the patient's head position. PATIENTS AND METHODS To analyze the degree and time course of refractive changes with respect to head position, the authors performed objective refraction in five aphakic and five phakic silicone oil-instilled eyes with attached maculae using an automatic hand-held refractometer. In each patient, 25 measurements were taken at short intervals using a hand-held autorefractometer with the patient in different positi…
Nonlinear effects of respiration on the crosstalk between cardiovascular and cerebrovascular control systems.
2016
Cardiovascular and cerebrovascular regulatory systems are vital control mechanisms responsible for guaranteeing homeostasis and are affected by respiration. This work proposes the investigation of cardiovascular and cerebrovascular control systems and the nonlinear influences of respiration on both regulations through joint symbolic analysis (JSA), conditioned or unconditioned on respiration. Interactions between cardiovascular and cerebrovascular regulatory systems were evaluated as well by performing correlation analysis between JSA indexes describing the two control systems. Heart period, systolic and mean arterial pressure, mean cerebral blood flow velocity and respiration were acquired…
Non-uniform multivariate embedding to assess the information transfer in cardiovascular and cardiorespiratory variability series
2012
The complexity of the short-term cardiovascular control prompts for the introduction of multivariate (MV) nonlinear time series analysis methods to assess directional interactions reflecting the underlying regulatory mechanisms. This study introduces a new approach for the detection of nonlinear Granger causality in MV time series, based on embedding the series by a sequential, non-uniform procedure, and on estimating the information flow from one series to another by means of the corrected conditional entropy. The approach is validated on short realizations of linear stochastic and nonlinear deterministic processes, and then evaluated on heart period, systolic arterial pressure and respira…
Cardiopulmonary resuscitation in prone position: A scoping review.
2020
Introduction The ongoing pandemic of COVID-19 brought to the fore prone positioning as treatment for patients with acute respiratory failure. With the increasing number of patients in prone position, both spontaneously breathing and mechanically ventilated, cardiac arrest in this position is more likely to occur. This scoping review aimed to summarize the available evidence on cardiopulmonary resuscitation in prone position (‘reverse CPR’) and knowledge or research gaps to be further evaluated. The protocol of this scoping review was prospectively registered on 10th May 2020 in Open Science Framework (https://osf.io/nfuh9). Methods We searched PubMed, EMBASE, MEDLINE and pre-print repositor…
Feldenkrais ‘Functional Integration’ Increases Body Contact Surface in the Supine Position: A Randomized-Controlled Experimental Study
2018
Feldenkrais ‘Functional Integration’ (FI) is a widely used type of body work with a focus on the continuous integration of body sensations and awareness with movement. The method is, amongst others, known for improving balance in aging populations, but also for its ability to relax muscles. With participants treated in the supine position FI is potentially changing the surface area of the body in contact with the surface on which a participant is lying. So far, no prior study has assessed this claim. We evaluated objectively and subjectively if a treatment with FI would induce changes in pressure and contact surface of the body on the mat. Thirty volunteers received an individual treatment …
A comparison of the antihypertensive action of propranolol and the optical isomers of N-isopropyl-p-nitrophenylethanolamine (INPEA)
1969
In hypertensive patients, the effect of propranolol and of the optical isomers of N-isopropyl-p-nitrophenylethanolamine (INPEA) on blood pressure was studied. Single oral doses of 40 mg propranolol, 700 mg (−)-INPEA and 700 mg (+)-INPEA decreased supine systolic as well as standing systolic and diastolic blood pressure. Single intravenous doses of 75 mg (−)-INPEA and 75 mg (+)-INPEA lowered supine systolic and diastolic blood pressure. The antihypertensive action of the beta adrenergic blocking levorotatory isomer of INPEA and of the dextrorotatory isomer, which is devoid of beta adrenergic blocking activity, did not differ. It is concluded from these results that the antihypertensive actio…
Vestibular adaptation to centrifugation does not transfer across planes of head rotation
2008
Out-of-plane head movements performed during fast rotation produce non-compensatory nystagmus, sensations of illusory motion, and often motion sickness. Adaptation to this cross-coupled Coriolis stimulus has previously been demonstrated for head turns made in the yaw (transverse) plane of motion, during supine head-on-axis rotation. An open question, however, is if adaptation to head movements in one plane of motion transfers to head movements performed in a new, unpracticed plane of motion. Evidence of transfer would imply the brain builds up a generalized model of the vestibular sensory-motor system, instead of learning a variety of individual input/output relations separately. To investi…
An Empirical Mode Decomposition Approach to Assess the Strength of Heart Period-Systolic Arterial Pressure Variability Interactions.
2020
This work proposes an empirical mode decomposition (EMD) method to assess the strength of the interactions between heart period (HP) and systolic arterial pressure (SAP) variability. EMD was exploited to decompose the original series (OR) into its first, and fastest, intrinsic mode function (IMF1) and the residual (RES) computed by subtracting the IMF1 from OR. EMD procedure was applied to both HP and SAP variability series. Then, the cross correlation function (CCF) was computed over OR, IMF1 and RES series derived from HP and SAP variability in 13 healthy subjects (age 27±8 yrs, 5 males) at rest in supine position (REST) and during head-up tilt (TILT). The first CCF maximum at negative ti…
Stellenwert der Spirometertriggerung für die hochauflösende Computertomographie der Lunge in Inspiration und Exspiration
1998
PURPOSE To compare mean lung density (MLD) of paired inspiratory and expiratory thin-section CT scans acquired after patient instruction or using spirometric gating. MATERIALS AND METHODS 21 patients (13 m, 8 f. median age 59 years, two with normal lung function, 15 with obstructive, 4 with restrictive impairment) underwent thin-section CT. Paired inspiratory and expiratory scans were performed in the upper, middle and lower lung fields. They were acquired after automatic patient instruction with constant intervals between instruction and scan. Spirometrically gated scans were acquired within 4 days at 80% and 20% of vital capacity (VC) which has been determined on the CT scanner in supine …
Reliability of Short-Term Heart Rate Variability Indexes Assessed through Photoplethysmography
2018
The gold standard method to monitor heart rate variability (HRV) comprises measuring the time series of interbeat interval durations from electrocardiographic (ECG) recordings. However, due to the widespread use, simplicity and usability of photoplethysmographic (PPG) techniques, monitoring pulse rate variability (PRV) from pulse wave recordings has become a viable alternative to standard HRV analysis. The present study investigates the accuracy of PRV, measured as a surrogate of HRV, for the quantification of descriptive indexes computed in the time domain (mean, variance), frequency domain (low-to-high frequency power ratio LF/HF, HF band central frequency) and information domain (entropy…