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PubMed2002

[Platypnoea-orthodeoxia syndrome. Diagnosis, etiology, treatment].

Platypnoea-orthodeoxia (P.O.) syndrome is the association of dyspnoea and arterial oxygen desaturation aggravated in the erect position and relieved in the supine position. Initially considered very rare (20 cases reported over fifty years) and occurring essentially in patients having undergone pneumonectomy, it in fact occurs much more frequently if only it is looked for (20 extra cases reported in a single year). Some new aetiologies have been described, in particular dilatations or aneurysms of the ascending aorta. Diagnosis is made easier if the oxygen saturation is measured in the supine position when it is normal, and in the erect position when it falls considerably. Another argument is added by the small effect of inspiration of high concentrations of oxygen. Contrast echocardiography confirms the right-left shunt and allows estimation of the site. This is usually situated at the atrial level, via an inter-atrial communication or more often a patent foramen ovale; as a rule the area of dehiscence having been modified by the associated pathology allowing the right-left shunt despite normal right pressures. Exceptionally the shunt is situated at the vascular or pulmonary parenchymal level. Poor tolerance of P.O. syndrome justifies a therapeutic procedure; this is usually closure of the septal fault with an occluder introduced percutaneously; the results are generally highly spectacular.

Aortic Aneurysm↗

PubMed1998

Does the supine sleeping position have any adverse effects on the child? II. Development in the first 18 months. ALSPAC Study Team.

OBJECTIVE: To assess whether the recommendations that infants sleep supine could have adverse consequences on their motor and mental development. DESIGN: A prospective study of infants, delivered before, during, and after the Back to Sleep Campaign in the United Kingdom, followed to 18 months of age. SUBJECTS: The children were participants of the Avon Longitudinal Study of Pregnancy and Childhood born to mothers resident in the three former Bristol-based health districts of Avon, with expected date of delivery from April 1, 1991 to December 31, 1992. Questionnaires were completed on sleeping position at 4 to 6 weeks of age and sets of standardized questions on development at 6 and 18 months. MAIN OUTCOME MEASURES: Social, communication, fine and gross motor, and total developmental scales based on the Denver Developmental Screening Test at 6 and 18 months. RESULTS: After adjustment for 27 factors using multiple regression, 3 of the 10 scales and subscales significantly distinguished between front and back sleeping position. At 6 months of age, infants put to sleep on their front had a mean score 0.38 SD (95% confidence interval [CI]: 0.28, 0.49) higher on the gross motor scale, 0.11 SD (95% CI: 0.00, 0.23) higher in the social skills scale, and a total development score 0.20 SD (95% CI: 0.10, 0.30) higher than those on their backs. These differences were no longer apparent at 18 months. CONCLUSIONS: There is some evidence that putting infants to sleep in the supine position results in a reduced developmental score at 6 months of age, but this disadvantage appears to be transient. Weighing this against the adverse health effects demonstrated with the prone sleeping position, these results should not change the message of the Back to Sleep Campaign.

Child Development↗

PubMed1978

Effect of labetalol on plasma noradrenaline and adrenaline in hypertensive man.

Injection i.v. of labetalol, a new adrenergic alpha- and beta-blocking agent, decreased arterial blood pressure in 9 hypertensive subjects resting in the supine position, when standing and during supine exercise. Heart rate after labetalol was unchanged in the resting supine position, and it fell in the latter two conditions. Plasma noradrenaline concentration was higher after labetalol in all three experiments as compared to a control study. Plasma adrenaline after labetalol was increased only in the standing position, when the highest plasma noradrenaline concentrations were observed. Blood glucose concentration tended to increase after labetalol, but the difference was not statistically significant. The changes in plasma noradrenaline and blood glucose after labetalol mimic findings observed after alpha-adrenergic receptor blockade. The beta-adrenergic receptor blocking property of labetalol is responsible for the reduced heart rate and it is likely to contribute to the higher plasma noradrenaline concentration observed when standing and during supine exercise.

Adult↗

PubMed1983

[Role of body position during the carotid sinus stimulation test in the diagnosis of cardio-inhibitory carotid sinus syndrome].

The effect of body position during carotid sinus massage (CSM) for diagnosis of carotid sinus syndrome (CSS) of the cardioinhibitory type (CI) is not yet defined in the literature. The diagnosis of CSS-CI was made in 17 patients, the age range was 54 to 87 years (mean 74,7) on the basis of the following criteria: --history of recurrent syncope; --reproduction of symptoms during CSM repeated in different days in the presence of ventricular asystole that lasted more than 3 seconds; --absence of a vasodepressor reflex capable of producing symptoms, after a CI reflex was abolished by intravenous atropine; the blood pressure drop never exceeded 40 mmHg; --exclusion of other causes of syncope. In every patient the CSM was made in the supine position. If the test results were normal or left diagnostic doubts, the CSM was performed again in the standing position. Three different groups of patients were identified: a) normal result in the supine position, abnormal result in the standing position (cases 1 through 6); b) abnormal response both in the supine and in the standing position (7 and 8); c) abnormal response in the supine position, normal result in the standing position (9 and 10). In the cases 11 through 17 the CSM was not performed in the standing position because it was sufficiently diagnostic in the supine position. It is concluded that in the 35% of cases (6 of 17) the diagnosis of CSS-CI was obtained only after CSM was performed on the standing patient. In 53% of cases (9 of 17) the diagnosis was defined by CSM in supine position.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1992

Central action of atropine on cardiovascular reflexes in humans.

Effects of exciting the central nervous system (CNS) with low doses of atropine on cardiovascular reflexes was investigated in 6 healthy volunteers. Cumulative doses of atropine sulfate (1.43-28.57 micrograms/kg intravenously, i.v.) were used. The ECG parameters used to quantify the nervous activities on the heart were ratios of the longest to the shortest R-R intervals recorded during forced expirations and deep inspirations (respiratory sinus arrhythmia), the ratio of the longest to the shortest R-R intervals which occur immediately after one rises from a low sitting position (30:15 ratio), and the SD of R-R intervals recorded in standing and supine positions. Very low doses of atropine (1-3 micrograms/kg) increased the 30:15 ratios from (means +/- SEM) 1.21 +/- 0.07 to 1.34 +/- 0.04 (60% increase, p less than 0.01) and SD recorded in standing positions from 32.4 +/- 3.5 to 56.0 +/- 11.0 ms (71% increase, p less than 0.01). Respiratory sinus arrhythmia was not affected in either the standing or supine position, nor was SD recorded in supine positions significantly affected by these low doses of atropine. The only indexes increased by low doses of atropine were those that measure cardiovascular responses to active standing, consistent with an increased excitability of the medullary cardiovascular (vasomotor) centre. There was no evidence of central vagal excitation caused by low doses of atropine in the conscious, spontaneously breathing volunteers. The increased excitability of the medullary cardiovascular centre in response to a low dose of atropine may suggest that normal responses of this centre to arterial baroreceptor stimulation is restrained by a cholinergic inhibitory pathway.

Atropine↗

PubMed2003

Supine body position is an important factor influencing postprandial ambulatory blood pressure.

BACKGROUND: Although body position is known to be an important factor influencing the results of ambulatory blood pressure monitoring (ABPM), even very recent studies assessing postprandial blood pressure (BP) have not taken into account the possibility that the examined subjects were lying down after a meal. We addressed this issue by analysing diurnal BP profiles together with subject's reports on supine rest periods and meal consumption during ABPM. MATERIAL/METHODS: The ABPM results of 109 non-medicated subjects were analysed (age 40+/-12 years, daytime BP 132/84+/-15/11 mmHg). BP and heart rate (HR) changes were assessed on the basis of 2-hour means. RESULTS: Subjects who lay down within 2 hours after a meal showed significantly greater decreases in systolic and diastolic BP and HR than individuals who did not: -10+/-10 vs. 1+/-10 mmHg, -11+/-10 vs. -3+/-7 mmHg, and -7+/-9 vs. 0+/-11 beats/min, respectively. The BP decrease was greater when the duration of supine rest was longer. There were no significant differences between BP/HR changes during those periods when the subjects lay down within 2 hours after the meal and BP/HR changes during those periods when supine rest was not preceded by a meal. The mean changes for the latter group were -9+/-10 mmHg, -11+/-8 mmHg, and -9+/-9 beats/min. for SBP, DBP, and HR, respectively. CONCLUSIONS: Our results indicate that supine body position is an important factor, which may influence postprandial BP investigated by ABPM. Body position should always be taken into consideration when ABPM results are analysed.

Adult↗

PubMed2007

[Cyclorotation of the eye in wavefront-guided LASIK using a static eyetracker with iris recognition].

PURPOSE: Centration of the ablation zone decisively influences the result of wavefront-guided LASIK. Cyclorotation of the eye occurs as the patient changes from the sitting position during aberrometry to the supine position during laser surgery and may lead to induction of lower and higher order aberrations. METHODS: Twenty patients (40 eyes) underwent wavefront-guided LASIK (B&L 217z 100 excimer laser) with a static eyetracker driven by iris recognition (mean preoperative SE: -4.72+/-1.45 D; range: -1.63 to -7.00 D). The iris patterns of the patients' eyes were memorized during aberrometry and after flap creation. RESULTS: The mean absolute value of the measured cyclorotation was -1.5+/-4.2 degrees (range: -11.0 to 6.9 degrees ). The mean cyclorotation was 3.5+/-2.7 masculine (range: 0.1 to 11.0 degrees ). In 65% of all eyes cyclorotation was >2 masculine. CONCLUSIONS: A static eyetracker driven by iris recognition demonstrated that cyclorotation of up to 11 degrees may occur in myopic and myopic astigmatic eyes when changing from a sitting to a supine position. Use of static eyetrackers with iris recognition may provide a more precise positioning of the ablation profile as they detect and compensate cyclorotation.

Adult↗

PubMed1987

A controlled, double-blind, cross-over study of terodiline in motor urge incontinence.

In a placebo-controlled, randomized, double-blind, cross-over study, terodiline (50 mg/d) was compared with emepronium (600 mg/d) in 20 patients with motor urge incontinence. Evaluation of clinical efficacy was based on changes in micturition pattern, flow measurements, residual urine, cystometry and patient preferences, and safety on adverse reactions, blood chemistry, urine examinations and ECG. The number of voluntary micturitions decreased from a mean of 21.5 per 48 h on placebo by 1.6 on terodiline and 2.8 on emepronium. Involuntary micturitions decreased from 3.6 per 48 h by 1.3 on both treatments (p less than 0.05). The maximal flow rate decreased from a mean of 24.5 ml/sec to 19.6 ml/sec on emepronium and increased to 25.4 ml/sec on terodiline. Residual urine decreased from a mean of 54 ml to 49 ml on terodiline and increased to 60 ml on emepronium. Volume at first desire to void in the supine position increased on emepronium by 44 ml (p less than 0.05) and on terodiline by 3 ml, on the upright position by 11 ml and 18 ml, respectively. Bladder capacity increased in the supine position on emepronium by 32 ml and decreased on terodiline by 8 ml, in the upright position increased by 9 ml and 5 ml, respectively. The bladder pressure at first desire to void in the supine position increased on emepronium by 2 cmH2O, and decreased on terodiline by 2 cmH2O. The intravesical pressure at strong desire to void decreased on emepronium by 6 cmH2O and on terodiline by 7 cmH2O, in the upright position by 2 cmH2O and 1 cmH2O, respectively. 39% of the patients preferred terodiline, 39% emepronium and 22% placebo.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed2005

Trunk position in supine of infants born preterm and at term: an assessment using a computerized pressure mat.

PURPOSE: Trunk position may influence motor, cognitive, and social development during infancy and early childhood and has not been quantitatively assessed. The purpose of this study was to assess the trunk positions of infants born at term and preterm in supine using a computerized pressure mat. METHODS: Trunk position was represented as a ratio of head and pelvis to trunk pressure. Eighteen healthy infants born preterm with a mean gestational age of 31.9 weeks (25.0-34.6) and fifteen healthy infants born at term with a mean gestational age of 38.9 weeks (37.3-40.6) were assessed at 38 to 43 weeks gestational age. RESULTS: Infants born at term spent more than two-thirds of the time in either flexed or neutral trunk positions. No significant differences were found between infants born preterm and those born at term in total duration of flexion or extension or in flexion event duration. CONCLUSION: This study provides evidence that infants born preterm may not exhibit greater trunk extension tendencies in supine than infants born at term. Results should be interpreted with caution, however, because of the small sample size and large variability observed within the subject groups. Infants born at less than 30 weeks of gestation may demonstrate greater extension tendencies than those born at more than 30 weeks of gestation.

Case-Control Studies↗

PubMed1998

Inhaled air trapping effect of Japanese bedding as a risk of sudden unexpected death in infancy.

We assessed some Japanese bedding on the assumption of the effects of air trapping using an infant mannequin. The change of CO2 concentration in the airway of a mannequin head placed on bedding was continuously monitored using a CO2 analyzer during simulated breathing. To compare the level of CO2 dispersal among different items of bedding, CO2 half time (t1/2) values were used. The t1/2 values were calculated by measuring the time required for the expired percent CO2 to reach 1/2 the initial percent end-tidal PCO2. We also measured softness and resistance to airflow (R) of the same items. As for the bedding, 4 types of futon and several types of bottom sheets/towels were combined. The t1/2 value in supine position was 9.8 seconds. When the model was placed prone on futon, the t1/2 values increased to 14.1 seconds (hard mattress type)--17.2 seconds (soft cotton-like futon). With respect to present Japanese baby futon (hard mattress type), there may be a relatively low potential for rebreathing to occur, compared with soft futon. In every case, the t1/2 value was prolonged by the use of a towel spread on the futon. CO2 dispersal may depend not only on the softness of the futon, but also on the combination of bottom sheet/towel and mattress. There was no relationship between R values and t1/2 values. The potential of rebreathing increased in face down position among all bedding, and supine position was the best CO2 dispersal position.

Bedding and Linens↗

PubMed1997

Does the supine sleeping position have any adverse effects on the child? I. Health in the first six months. The ALSPAC Study Team.

OBJECTIVE: To assess whether the recommendations that infants sleep supine could have adverse health consequences. DESIGN: A prospective study of infants, delivered before, during, and after the Back to Sleep Campaign in the United Kingdom (UK), followed to 6 months of age. The children were part of the Avon Longitudinal Study of Pregnancy and Childhood (ALSPAC). Subjects. Singletons born to mothers resident in the three former Bristol-based health districts of Avon in the period June 1991 to December 1992, and for whom questionnaires were completed on sleeping position at 4 to 6 weeks of age (n = 9777); for these infants 8524 questionnaires were also completed at 6 to 8 months of age. MAIN OUTCOME MEASURES: Subjective measures of health, the presence of specific signs and symptoms, duration of sleep at night, and calling the family doctor to the home. RESULTS: Of 43 outcomes considered, after adjustment for 12 factors using logistic regression only 2 were associated with raised risk among infants put to sleep on their back (diaper rash and cradle cap). Infants put to sleep prone had increased risk of a number of health outcomes, including cough and possibly pyrexia. CONCLUSIONS: There is no evidence that putting infants to sleep in the supine position results in increased morbidity, although changes in prevalence of rare disorders would not have been identified.

Adult↗

PubMed1993

Squatting position for delivery.

The study was conducted on 200 normal pregnant women who were randomly classified into 2 groups of 100 cases each. The control group comprised mothers in supine position throughout labour and delivery (46 primigravidae and 54 multigravidae). The squatting group consisted of cases who were kept ambulatory during the 1st stage and were asked to squat on ordinary delivery cots during the 2nd stage of labour. Third stage of labour was conducted in supine position. The squatting group comprised 42 primigravidae and 58 multigravidae. There was a mean difference (shortening) of 3 hours in primigravidae and 2 hours in multigravidae in the duration of 1st stage of labour between the squatting and control groups. In the duration of 2nd stage of labour the mean differences in primigravidae and multigravidae of the squatting and control groups were 20 and 13.5 minutes respectively. In the squatting group there were 79 normal vaginal delivery, 16 forceps delivery and 5 caesarean sections whereas in the control group there were 80, 18 and 2 cases respectively. Although foetal complications were comparable in both the groups, the incidence of maternal injuries was observed in 14 cases in control group and 38 cases in squatting group. It was concluded that without proper birthing chairs which can give good perineal support, the usual supine position is preferable.

Adult↗

PubMedDate not supplied

Clinical feasibility of echocardiographic automated border detection in monitoring left ventricular response to acute changes of preload in normal subjects.

Echocardiographic automated border detection (ABD) provides an instantaneous measurement of left ventricular (LV) volume and its rate of change. We tested the clinical feasibility of ABD in monitoring on-line LV response to acute changes in preload. We examined 20 healthy males in the supine position, with legs elevated, back in the supine position, 5 min after the inflation of blood pressure cuffs at the root of the four limbs, 5 min after the deflation of cuffs. End-diastolic and end-systolic LV volumes significantly increased with elevated legs and decreased during cuff inflation; ejection fraction remained unchanged. Peak filling and peak emptying rates did not change with elevated legs and increased significantly during cuff inflation. The values of LV parameters were stable in the three resting conditions, demonstrating a good reproducibility of the ABD technique. Our results demonstrate that ABD may be useful in clinical practice for monitoring on-line small acute changes in LV volume and function.

Adult↗

PubMed1995

Plasma catecholamines and cyclic AMP response during head-up tilt test in patients with neurocardiogenic (vasodepressor) syncope.

To examine hemodynamic, plasma catecholamines, and cyclic AMP changes during tilt in patients with neurocardiogenic (vasodepressor) syncope, six patients underwent 80 degrees head-up tilt test for 10 minutes with isoproterenol infusion (1-3 micrograms/min). Venous blood was sampled in the supine position, at 3 minutes of tilt, and at the onset of vasodepressor reaction during tilt. All patients had previous tilt studies in which vasodepressor syncope had been induced reproducibly (mean 3.3 episodes in each patient). Syncope was induced at 6.1 +/- 0.4 minutes of tilt with an infusion of isoproterenol (mean 1.7 +/- 0.3 micrograms/min). Although arterial pressure and heart rate did not change significantly between in the supine position and at 3 minutes of tilt, plasma norepinephrine increased significantly at 3 minutes of tilt (0.44 +/- 0.10 ng/mL; P < 0.05) and at the onset of vasodepressor reaction (0.49 +/- 0.12 ng/mL; P < 0.01) compared to the supine position with isoproterenol (0.34 +/- 0.10 ng/mL). Also, cyclic AMP (cAMP) increased significantly at 3 minutes of tilt (25.3 +/- 2.0 pmol/mL; P < 0.005) and at the onset of vasodepressor reaction (29.6 +/- 1.7 pmol/mL; P < 0.005) compared to the supine position with isoproterenol (20.4 +/- 1.9 pmol/mL). After administration of selective beta 1-blocker, metoprolol (40 mg/day), plasma norepinephrine, and cAMP during tilt did not change significantly compared to baseline tilt. However, metoprolol prevented the syncope in 3 of 6 patients. After administration of beta 1-, beta 2-blocker, propranolol (30 mg/day), cAMP at 3 minutes of tilt decreased significantly compared to the baseline tilt (16.9 +/- 1.4 pmol/mL vs 25.3 +/- 2.0 pmol/mL; P < 0.05) and propranolol prevented the syncope in all six patients. We concluded that the increase of cAMP may play an important role for the induction of vasodepressor reaction in patients with neurocardiogenic (vasodepressor) syncope. The concentration of cAMP showed more sensitive response to vasodepressor reaction than that of norepinephrine.

Adrenergic beta-Agonists↗

PubMed2006

Relationship of progression of visual field damage to postural changes in intraocular pressure in patients with normal-tension glaucoma.

PURPOSE: To evaluate whether postural changes of intraocular pressure (IOP) are associated with progression of visual field damage in patients with normal-tension glaucoma (NTG). DESIGN: Prospective, noncomparative, nonrandomized study. PARTICIPANTS: Sixty eyes of 33 patients with NTG. METHODS: Intraocular pressure, blood pressure (BP), and pulse rate (PR) were measured in both sitting and supine positions. Visual fields were examined using Humphrey Field Analyzer (HFA; Zeiss-Humphrey Instruments, Inc., San Leandro, CA). Changes in mean deviation (MD) per year (dB/year), that is, MD slope, were calculated by linear regression analysis of the HFA Statpac 2 program. MAIN OUTCOME MEASURES: The relationship between postural changes of IOP and MD slope was analyzed. The correlation between postural changes of IOP and cardiovascular parameters such as BP and PR also was analyzed. RESULTS: The IOP in the supine position was significantly higher than that in the sitting position (P<0.001, paired t test). There was no significant correlation between MD slope and sitting IOP (Pearson r = 0.172; P = 0.188), but a significant correlation was found between MD slope and supine IOP (r = -0.261; P = 0.043). The MD slope significantly correlated with IOP elevation caused by the postural change (r = -0.682; P<0.001). The systolic BP in the supine position correlated with postural changes of IOP (r = 0.364; P = 0.004), but other cardiovascular parameters did not correlate with IOP parameters. CONCLUSIONS: The progression of visual field damage in NTG is associated with IOP in the supine position and the magnitude of IOP elevation accompanying postural changes. These results suggest that deterioration in NTG may occur when patients are lying flat during sleep.

Aged↗

PubMed1999

Supine body position as a risk factor for nosocomial pneumonia in mechanically ventilated patients: a randomised trial.

BACKGROUND: Risk factors for nosocomial pneumonia, such as gastro-oesophageal reflux and subsequent aspiration, can be reduced by semirecumbent body position in intensive-care patients. The objective of this study was to assess whether the incidence of nosocomial pneumonia can also be reduced by this measure. METHODS: This trial was stopped after the planned interim analysis. 86 intubated and mechanically ventilated patients of one medical and one respiratory intensive-care unit at a tertiary-care university hospital were randomly assigned to semirecumbent (n=39) or supine (n=47) body position. The frequency of clinically suspected and microbiologically confirmed nosocomial pneumonia (clinical plus quantitative bacteriological criteria) was assessed in both groups. Body position was analysed together with known risk factors for nosocomial pneumonia. FINDINGS: The frequency of clinically suspected nosocomial pneumonia was lower in the semirecumbent group than in the supine group (three of 39 [8%] vs 16 of 47 [34%]; 95% CI for difference 10.0-42.0, p=0.003). This was also true for microbiologically confirmed pneumonia (semirecumbent 2/39 [5%] vs supine 11/47 [23%]; 4.2-31.8, p=0.018). Supine body position (odds ratio 6.8 [1.7-26.7], p=0.006) and enteral nutrition (5.7 [1.5-22.8], p=0.013) were independent risk factors for nosocomial pneumonia and the frequency was highest for patients receiving enteral nutrition in the supine body position (14/28, 50%). Mechanical ventilation for 7 days or more (10.9 [3.0-40.4], p=0.001) and a Glasgow coma scale score of less than 9 were additional risk factors. INTERPRETATION: The semirecumbent body position reduces frequency and risk of nosocomial pneumonia, especially in patients who receive enteral nutrition. The risk of nosocomial pneumonia is increased by long-duration mechanical ventilation and decreased consciousness.

Aged↗

PubMed1999

Diagnostic utility of mechanical, pharmacological and orthostatic stimulation of the carotid sinus in patients with unexplained syncope.

OBJECTIVES: The purpose of the present study was to systematically evaluate the diagnostic utility of mechanical, pharmacological and orthostatic stimulation of the carotid sinus in a consecutive series of patients with recurrent unexplained syncope. BACKGROUND: Carotid sinus hypersensitivity (CSH) is an infrequently recognized cause of recurrent unexplained syncope usually diagnosed by carotid sinus massage (CSM) in the supine position. The diagnostic utility of systematic assessment of mechanical, pharmacological and orthostatic stimulation of the carotid sinus has not been clearly established. METHODS: Eighty consecutive patients (63 +/- 12 years) with a history of recurrent unexplained syncope (mean episodes: 6 +/- 3); 30 age-matched controls (65 +/- 14 years) and 16 patients (59 +/- 12 years) with syncope not related to CSH were studied. Pharmacological stimulation of the carotid sinus was achieved by randomly administering bolus injections of nitroprusside and phenylephrine. Mechanical stimulation of the carotid sinus was performed by CSM applied for 5 s in the supine position and after 2 min at 60 degrees. A 60 degree low-dose isoproterenol head-up tilt test (HUTT) was also performed for a total duration of 30 min. RESULTS: Carotid sinus hypersensitivity was elicited by CSM in the supine position in seven (8.7%) patients, two (6.6%) controls and one (6.3%) patient with syncope unrelated to CSH, compared with 48 (60%) patients, two (6.6%) controls and one (6.3%) syncope unrelated to CSH patient after 60 degree HUTT, increasing the diagnostic yield by 51%. Baroreceptor gain was significantly reduced in the CSH group. Head-up tilt test was positive in 12 (25%) patients with CSH, two (6.6%) controls and two (12%) with documented syncope but not positive in any of the patients in which syncope remained unexplained. Diagnostic accuracy was enhanced by 38% (31% supine vs. 69% upright) when CSM was performed at 60 degrees. CONCLUSIONS: CSH was documented in 68% of patients, 8.7% in the supine position and 60% in the upright position. Sensitivity was increased by 51%, and diagnostic accuracy was enhanced by 38% by performing CSM in the upright position. Decreased baroreceptor gain was documented and may play a role in the pathophysiology of CSH.

Aged↗

PubMed1996

Body position, age and mass effect of adiposity on adipose tissue red cell flux in morbid obesity.

OBJECTIVE: To measure red cell flux of adipose tissue in morbidly obese patients' pannus in the upright and supine position to determine factors which would render the lower pannus susceptible to ischemic necrosis. DESIGN: A cohort study of morbidly obese subjects without ischemic necrosis. SETTING: University teaching hospital. PATIENTS: Twenty-three consecutive morbidly obese patients referred for gastroplasty. MEASUREMENTS: Red cell flux, measured as RMS voltage by a laser Doppler velocimeter. An optical fiber with a tip diameter of 250 mu was inserted into the upper and lower pannus and output recorded in the upright and supine positions. Other variables recorded were age, BMI, blood pressure and serum lipids. RESULTS: Adipose tissue red cell flux demonstrates considerable spatial and temporal heterogeneity from subject to subject and in various locations in the pannus. No differences in red cell flux were detected in response to change in position. However, regression analysis demonstrated that the gradient between the upper and lower abdomen in the supine position was increasingly positive with age and in the upright position it was increasingly positive with increasing weight or BMI. CONCLUSIONS: These data suggest that red cell flux is heterogeneously distributed in the abdominal pannus and is not greatly influenced by body position. However, with increasing age and adiposity there is a gradient for decreased red cell flux to the lower portion of the pannus. This may be a factor in rendering this part of the pannus prone to ischemic fat necrosis.

Abdomen↗