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Results for “Supine Position”

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PubMed1994

Effects of acute allergen exposure on posture-induced changes in airway responsiveness to methacholine in asthma.

BACKGROUND: The influence of an allergen challenge on recumbency induced changes in airway responsiveness to methacholine was documented in seven nonsmoking subjects with stable mild asthma (3M, 4F). METHODS: All subjects spent four hours (8 to 12 AM) in the supine position before and 24 hours after an allergen challenge that induced a dual asthmatic response. FEV1 was measured hourly in the supine position and a methacholine challenge was done in the sitting position before and after each 4-hour period. None used bronchial antiinflammatory drugs before or during the study. RESULTS: The mean maximal fall in FEV1 (+/- SEM) was 31.0 +/- 1.1% within one hour of the last allergen inhalation and 27.5 +/- 4.9% between two and eight hours later. Presupine/postsupine session FEV1 (%pred +/- SEM) was unchanged either at baseline or postallergen challenge sessions, with values of 89.3 +/- 2.7/88.3 +/- 5.1 and 86.6 +/- 4.2/87.4 +/- 5.7. Presupine/postsupine PC20 methacholine was slightly reduced but this did not reach statistical significance (P > .05), with a mean PC20 (mg/mL) of 0.83 +/- 1.44/0.52 +/- 1.46 (preallergen session); 0.55 +/- 1.44/0.39 +/- 1.37 (postallergen challenge session). This delta PC20 (baseline/post-session) did not differ between the two sessions (P > .05). The delta PC20 was not correlated with the magnitude of the late asthmatic response to allergen nor the postallergen increase in airway responsiveness. CONCLUSIONS: We conclude that an acute allergen challenge does not significantly increase recumbency-induced changes in airway response to methacholine in patients with mild asthma. The possibility of a significant influence of pro-inflammatory stimuli on recumbency-induced changes in bronchomotor tone in more severe patients or if the stimulus is repeated should be further assessed.

Adult↗

PubMed2003

Orthopnea and inspiratory effort in chronic heart failure patients.

STUDY OBJECTIVE: Orthopnea is a typical feature of patients with chronic heart failure (CHF), the factors contributing to it are not completely understood. We investigated changes in dyspnea and other respiratory variables, induced by altering posture (from sitting to supine) in 11 CHF patients (NYHA classes II-IV) and 10 control subjects. METHODS AND RESULTS: We measured dyspnea (Borg scale) the diaphragm pressure time product per minute (PTPdi/m, index of metabolic consumption), and mechanical properties of the lung (lung compliance (C,L) and resistances (R,L). CHF patients also underwent a trial of non-invasive mechanical ventilation (NIMV) in the supine position in order to ascertain whether unloading the inspiratory muscles could somehow relieve dyspnea. While sitting the PTPdi/min was significantly higher in CHF patients than in controls (181 +/- 54 cm H2O x s/min vs. 96 +/- 32; P<0.05). Assuming a supine position caused no major changes in controls, whereas CHF patients showed a significant worsening in dyspnea, a rise in PTPdi/min (243 +/- 97 p<0.01) and R,L (4.7 +/- 1.2 cm H2O/L x s sitting vs. 7.9 +/- 2.5 supine; P<0.01) and a decrease in C,L (0.08 +/- 0.02 L/cm H2O sitting vs. 0.07 +/- 0.01 supine; P<0.05). Applying NIMV to supine CHF patients significantly reduced the PTPdi/min to 81 +/- 42 (P<0.001). Changes in dyspnea, produced by varying position or applying NIMV, were significantly correlated with PTPdi/min (r=0.80, P<0.005 and r=0.58, P<0.01, respectively). CONCLUSIONS: CHF patients had a higher PTPdi/min than controls when sitting, and assuming a supine position induced severe dyspnea, a large rise in R,L, and a reduction in C,L so that PTPdi/min increased further. Orthopnea was strongly correlated with the increased diaphragmatic effort.

Cardiac Output, Low↗

PubMed1999

Changes in the size and location of kidneys from the supine to standing positions and the implications for block placement during total body irradiation.

PURPOSE: The use of total body irradiation (TBI) as a conditioning regimen for bone marrow transplantation often calls for partial transmission kidney blocks. These blocks are frequently designed based on the location of the kidneys during the abdominal computerized tomography (CT) scan. At our institution, TBI patients are treated in the standing position. As the kidneys can shift with different patient positions, a study was undertaken to evaluate the magnitude of the changes in the size and location of the kidneys from the supine CT position to the upright treatment position. METHODS AND MATERIALS: Intravenous contrast was administered to 15 patients. The patients were initially positioned supine on a simulator table and then positioned upright immediately in front of the image intensifier. PA radiographs were obtained with the patients in both positions. Changes in the size of the kidneys and their location relative to the vertebral bodies were noted. RESULTS: In going from the supine to upright position, all the kidneys shifted inferiorly between 0.5 cm and 7.5 cm with an average of 3.6 cm. Most of the kidneys also shifted in the transverse dimension and incurred a change in width. The range of the transverse shift was from 0.9 cm in the lateral direction to 4.9 cm medially. The maximum width broadening was 1.2 cm and the maximum decrease in width was 1.8 cm. CONCLUSIONS: When compared to the supine position, patients in the upright position show a dramatic inferior shift of the kidneys with other obvious, but less predictable, changes. For TBI treatments delivered in the upright position, kidney blocks should not be designed on the basis of supine abdominal CT scans.

Humans↗

PubMed2001

[Effect of surgical positioning and spinal anesthesia on lung function].

BACKGROUND: Various surgical positions, e.g., lithotomy, prone, or head-down positions influence respiratory mechanics. The aim of the present paper was to investigate whether particular surgical positions (lithotomy, lithotomy with head-down tilt, prone, prone with a roller placed under the abdomen) as well as spinal anaesthesia in lithotomy position impair the pulmonary function to a greater extent than supine position and whether they have to be considered as increasing the perioperative risk in elderly patients and patients with ventilatory disorders. METHODS: In two separate experimental series, we examined a) the influence of the surgical positions on the pulmonary function in 45 subjects (25 without and 20 with ventilatory disorders) and b) the effects of spinal anaesthesia in 25 urologic patients (9 without and 16 with ventilatory disorders). Static and dynamic lung function parameters were determined. Under spinal anaesthesia, the arterial O2 saturation and the end-expiratory partial pressure of CO2 were measured additionally. RESULTS: The most pronounced lung function decrease occurred with the transition from seated to supine position. Lithotomy and prone positions impaired the respiratory function only slightly. In elderly persons and in patients with ventilatory disorders, the spirometric changes tended to be stronger than in young persons, but were not considered to increase the perioperative pulmonary risk. A combination of lithotomy position and spinal anaesthesia did likewise not remarkably impair the respiratory function. CONCLUSIONS: Lithotomy and prone positions as well as spinal anaesthesia are not considered to be an additional risk factor for pulmonary function.

Adult↗

PubMed2004

Relationships among nocturnal jaw muscle activities, decreased esophageal pH, and sleep positions.

The purpose of this study was to examine the relationships among nocturnal jaw muscle activities, decreased esophageal pH, and sleep positions. Twelve adult volunteers, including 4 bruxism patients, participated in this study. Portable pH monitoring, electromyography of the temporal muscle, and audio-video recordings were conducted during the night in the subjects' homes. Rhythmic masticatory muscle activity (RMMA) episodes were observed most frequently, with single short-burst episodes the second most frequent. The frequencies of RMMA, single short-burst, and clenching episodes were significantly higher during decreased esophageal pH episodes than those during other times. Both the electromyography and the decreased esophageal pH episodes were most frequently observed in the supine position. These results suggest that most jaw muscle activities, ie, RMMA, single short-burst, and clenching episodes, occur in relation to gastroesophageal reflux mainly in the supine position.

Adult↗

PubMed1999

[Cardiovascular and metabolic response to dynamic stress echocardiography by patients with coronary heart disease and healthy probands].

25 patients with coronary heart disease (CHD, 62 +/- 9 years) and 18 subjects free from cardiovascular disease (28 +/- 9 years) were tested on a cycle ergometer using a graded incremental test protocol: a) in the common upright position, b) as dynamic stress echocardiography in a semi-supine position. Whereas no relevant differences could be detected between the two conditions for the healthy subjects concerning heart rate, blood pressure, and rate-pressure product (2 x 3 ANOVA, t-tests with alpha-adjustment), the CHD patients showed both significantly higher heart rates as well as a significantly higher rate-pressure product (50 W: 15,300 +/- 2973 mm Hg/min vs. 13,822 +/- 3042 mm Hg/min; 75 W: 18,028 +/- 3479 mm Hg/min vs. 16,337 +/- 2619 mm Hg/min) on equivalent stages during stress echocardiography if compared to the sitting position. There were no differences for systolic blood pressure in this group; the diastolic values were higher in the sitting position at rest and during 50 W. Lactate concentrations (determined only in the healthy subjects) were significantly higher on all stages during dynamic stress echocardiography. The workload at the individual anaerobic threshold (IAT) was significantly lower. In conclusion, we found a higher metabolic along with a similar cardiovascular strain at equivalent workloads in stress echocardiography compared to upright bicycle ergometry for healthy subjects. However, CHD patients have a higher cardiocirculatory load in the semi-supine position. When investigating these patients with stress echocardiography, higher heart rates of about 8 beats/min have to be expected for equivalent workloads if compared to the upright position.

Adult↗

PubMed2004

Lower esophageal sphincter pressure in patients with gastroesophageal reflux diseases and posture and time patterns.

Gastroesophageal reflux disease is caused predominantly by lower esophageal sphincter insufficiency. Reports suggest that it is possible to distinguish between two main mechanisms causing reflux: low basal sphincter pressure leading to free reflux, mostly occurring at night in the supine position, and increased transient lower esophageal sphincter relaxations with normal or increased resting pressure leading to reflux during the day in an upright position. Lower esophageal sphincter pressure (LESP)-- s determined by stationary pull-through manometry--was compared to profiles of acidic reflux measured by 24-h pH monitoring in 207 patients with proven gastroesophageal reflux disease. Differences in LESP were not significant among patients with reflux predominantly during the day in an upright position and those with reflux predominantly at night in a supine position (16.1 +/- 7.4 mmHg versus 15.1 +/- 7.8 mmHg; t-test: P = 0.355). For both patterns of LESP, there was a slight negative correlation with the amount of acidic reflux (determined as a percentage of time with pH < 4). Pearson correlation coefficients were -0.196 for upright refluxers and -0.137 for bipositional/supine refluxers (P = 0.006 and P = 0.049, respectively). As there are no differences in LESP with regard to posture or time patterns of acidic reflux it seems unlikely that upright reflux is associated with increased LESP, whereas supine reflux manifests due to a hypotensive LESP. Alternatively, it may be concluded that stationary pull-through manometry is inadequate for determining the cause of gastroesophageal reflux disease and is therefore of limited use in its routine diagnosis.

Adult↗

PubMed1988

Failure of impedance plethysmography to follow exercise-induced changes in limb blood flow.

1. The blood flow in the forearm and the calf of six healthy volunteers was measured at rest and after exercise by impedance plethysmography using pulsatile (QZp) and venous occlusion (QZocc) methods, and by venous occlusion strain gauge plethysmography (Qsg). 2. At rest, the impedance QZp method gave values slightly higher than those of Qsg. In the forearm, the ratio QZp to Qsg was 1.26 in the supine position and 1.97 in the upright sitting position. For the calf muscle, the ratios were 1.08 in the supine position and 1.23 in the upright position. 3. Immediately after exercise, Qsg increased from resting values of approximately 2-4 ml min-1 100 ml-1 to mean values of 16-25 ml min-1 100 ml-1 in upright and supine arm or leg exercise. In contrast, the QZp values after exercise increased to only 3.1-4.6 ml min-1 100 ml-1. QZocc likewise failed to show increases in flow except in the supine leg exercise, where flow increased to 8.7 ml min-1 100 ml-1. 4. In an additional subject, it was shown that electrode position had no significant effect on the QZp blood flow measurement after exercise. 5. The failure of QZp to accurately follow the change in Qsg with exercise was probably due in part to pulsatile venous outflow. In addition, changes in microvessel packed cell volume and shear rate may influence the observed QZp. It is concluded that impedance plethysmography is not valid for estimation of limb blood flow during reactive hyperaemia after exercise.

Adult↗

PubMed2005

Effect of low gravitational stimulation on the perception of target elevation: role of spatial expertise.

To examine the interindividual differences in the judgment of the visually perceived eye level (VPEL-upright position) and of the visually perceived apparent zenith (VPAZ-supine position) when the subject is subjected to low gravitational-inertial force (GIF), we independently altered GIF in two different populations: control subjects and spatial experts. Subjects were instructed to set a luminous target to the eye level while they were in total darkness and motionless or undergoing low radial acceleration with respect to the threshold of the otolithic system (0.015-1.67 m/sec2 for the VPEL and 0.55-2.19 m/sec2 for the VPAZ, respectively). Results showed that (1) low GIFs, close to those met during daily life, induced an eye level lowering in the upright and supine positions for the control group, and (2) the spatial expertise modified the influence of low GIF. Whereas an oculogravic illusion was found for the control group, this phenomenon was absent (VPAZ) or weaker (VPEL) for the spatial experts. Thus, the relations that the subjects maintain with their spatial environment and the knowledge acquired through experience modify the processing of sensory information and the perceptive construction resulting from it. The interindividual differences in sensitivity to the oculogravic illusion are discussed in terms of sensory dominance and of a better efficiency in the use of the available sensory information.

Gravitation↗

PubMed1997

Effect of body position on tongue posture in awake patients with obstructive sleep apnoea.

BACKGROUND: Snoring and obstructive sleep apnoea (OSA) are worse or may only occur in the supine position. The effect of body position on upper airway size has been reported, but the effect on tongue posture has not previously been examined. METHODS: Detailed measurements were made of tongue posture from upright and supine lateral cephalograms on 24 men with OSA and 13 men with non-apnoeic snoring matched for age, body mass index, and craniofacial skeletal pattern. Patients with OSA had apnoea/hypopnoea indices (AHI) of > 50/hour and/or apnoea indices (AI) of > 25/hour while non-apnoeic snorers had AHI of < 10/hour and AI of < 5/hour. RESULTS: In non-apnoeic snorers the tongue depth measurements for the superior-posterior portion of the tongue were larger in the supine than in the upright position (p < 0.05). There was no significant difference in tongue depth measurements between the upright and the supine position in the patients with OSA. CONCLUSIONS: When awake patients with OSA move from the upright to the supine position they maintain their upright tongue posture which may tend to protect against upper airway collapse secondary to the increased gravitational load on the tongue. In contrast, when awake non-apnoeic snorers move from the upright to the supine position a significant dorsal movement in the superior-posterior portion of the tongue is observed.

Awareness↗

PubMed2005

Correlation between office and peak nocturnal intraocular pressures in healthy subjects and glaucoma patients.

PURPOSE: To evaluate the correlations between office-hour intraocular pressures (IOP) and peak nocturnal IOP in healthy and glaucomatous eyes. DESIGN: Retrospective review of laboratory records. METHODS: We reviewed 24-hour data of IOP collected from 33 younger healthy subjects (aged 18 to 25 years), 35 older healthy subjects (aged 40 to 74 years), and 35 untreated older glaucoma patients (aged 40 to 79 years) housed in a sleep laboratory. Measurements of IOP were taken every 2 hours using a pneumatonometer in the sitting and supine positions during the diurnal/wake period (7 AM to 11 PM) and in the supine position during the nocturnal/sleep period. Correlations between average sitting or supine IOP in the right eye between 9:30 AM and 3:30 PM (office hours) and peak right eye IOP during the nocturnal hours were analyzed. RESULTS: The average values of supine IOP during office hours were found to have the strongest correlation with peak nocturnal IOP in older glaucoma subjects (r = .713, P < .001), whereas the correlation was less in older healthy subjects (r = .523, P < .01) and was absent in younger healthy subjects (r = .224, P = .21). The correlation between average sitting IOP values during office hours and peak nocturnal IOP was also strong in older glaucoma subjects (r = .601, P < .001) and moderate in older healthy subjects (r = .412, P < .05), but absent in younger healthy subjects (r = -.077, P = .672). CONCLUSION: Using a modification of the diurnal IOP curve, the magnitude of peak nocturnal IOP in untreated glaucoma patients can be estimated during routine office visits. Supine IOP measurements estimate peak nocturnal IOP better than sitting measurements. This estimation may provide the clinician with valuable information regarding the nocturnal IOP peak in glaucoma patients.

Adolescent↗

PubMed1997

Determining blood pressure in pregnancy. Positional hydrostatic effects.

OBJECTIVE: To evaluate positional hydrostatic effects on blood pressure determination during pregnancy. STUDY DESIGN: We studied 30 normotensive, pregnant women at 34-41 weeks of gestation. Blood pressures were taken in the sitting, left lateral, right lateral and supine positions with a two-minute stabilization period between positions. The bisacromial diameter was measured. Multivariate analysis of variance for repeated measures was used to evaluate the affect of position on blood pressure. RESULTS: Mean systolic pressure in the right arm was 2.6 mm Hg greater than that in the left arm (P < .05). There was no difference between the arms in diastolic blood pressure. Immediate blood pressure in the lower arm was no greater than in the higher arm in lateral positions, and there were no other significant positional effects. Observed blood pressures were significantly different than those theoretically expected on the basis of hydrostatic effects (P < .0001). CONCLUSION: Positional effects on blood pressure in the lateral positions do not appear immediately (within two minutes), indicating that hydrostatic pressure does not account for these changes. The well-documented blood pressure reduction from longer duration in the lateral position does not appear to be an artifact of hydrostatic effect. Repositioning pregnant women in the supine position to have the cuff at the level of the heart is unnecessary and often undesirable when fetal perfusion is an important consideration. We suggest that American Heart Association blood pressure guidelines stating that all measurements be taken with the cuff at the level of the heart to avoid hydrostatic pressure change be revised for pregnancy.

Adult↗

PubMed2005

Saliva transport to the distal esophagus.

OBJECTIVE: During esophageal acid clearance, saliva should reach the most distal esophagus. The mechanisms responsible for saliva transport are not completely understood but it is assumed that normal peristalsis plays a significant role. The aim of this study was to assess the role of esophageal peristalsis and gravity in saliva transport to the distal esophagus. MATERIAL AND METHODS: Esophageal transit and presence times of a 2-ml bolus of radiolabeled artificial saliva were assessed using concurrent scintigraphy and manometry in 10 healthy volunteers in the upright and supine positions before and after disruption of esophageal motility with sildenafil (50 mg). RESULTS: With normal peristalsis, there was no difference in saliva transit to the distal esophagus between supine and upright positions 3.9 (1.5- >60.0) versus 3.3 s (1.3-8.3). Low amplitude contractions did not affect saliva transit but the disappearance of contractions after sildenafil was associated with prolonged saliva transit in supine position 7.4 (1.0- >60.0). Saliva presence time was significantly prolonged in both the upright and supine positions by esophageal dysmotility. CONCLUSIONS: Saliva transport to the distal esophagus does not require complete normal peristalsis or gravity and mainly depends on an efficient pharyngeal pump. However, subjects in supine position with severe esophageal dysmotility might have both impaired volume clearance and delayed saliva transport, leading to abnormal acid clearance and esophagitis.

Adult↗

PubMed1993

Hemodynamic response to orthostatic stress in the elderly with systolic systemic hypertension before and after long-term thiazide therapy.

The hemodynamic effects of orthostatic stress in elderly subjects with systolic hypertension were studied before and after long-term hydrochlorothiazide therapy (50 mg daily). Sixteen nondiabetic men aged 70 +/- 1 (SE) years participated in the study initially, and 12 completed 1 year of therapy. Patients underwent 45 degrees head-up incline on a tilt table before, after 1 month and after 1 year of therapy. Hemodynamic variables were measured in the following situations: (1) the supine position, (2) immediately after completion of passive 45 degrees head-up position at 0 minute, (3) at 15 minutes in the tilted state while patients performed intermittent foot movements to minimize gravitational pooling and simulate the standing position outside the laboratory, and (4) after returning to the supine position. Systolic and diastolic blood pressure (BP) decreased significantly after 1 month of therapy, and this reduction was maintained up to 1 year in all aforementioned body positions, with the exception of diastolic BP at 0 minute of tilt, which was significant at 1 year only. Before therapy was begun, there was a significant reduction in systolic BP immediately after completion of tilting; however, this was statistically insignificant both at 1 month and 1 year of therapy. Thus, the data may help dispel the concern of exacerbating the hypotensive response to orthostatic stress in patients with systolic hypertension after long-term thiazide diuretic therapy.

Aged↗

PubMed2006

Asymmetry of right versus left intraocular pressures over 24 hours in glaucoma patients.

PURPOSE: To assess the asymmetry of 24-hour intraocular pressures (IOPs) between right and left eyes of untreated open-angle glaucoma (OAG) patients, and its influence on the monocular therapeutic trial. DESIGN: Experimental study with human patients. PARTICIPANTS: Forty-one subjects (40-78 years old) with untreated OAG. METHODS: Subjects were housed in a sleep laboratory for 24 hours. Intraocular pressures of both eyes were measured with a pneumatonometer every 2 hours with the patient in the sitting and supine positions from 7 am to 11 pm and in the supine position only from 11 pm to 7 am. Mean, peak, and trough IOPs were compared in right versus left eyes. The strength of association between right and left IOPs was assessed using coefficients of determination (R2). Validity of the monocular therapeutic trial was assessed by examining residual values from 2 linear regression models of right versus left IOP. MAIN OUTCOME MEASURES: Strength of association between IOPs of right and left eyes, and residual values from linear models of IOP. RESULTS: No statistically significant difference was found between mean, peak, or trough IOPs of right and left eyes over a 24-hour period. The strength of association for mean IOP was only moderate (R(2) = 0.421-0.623). Residual values of > or =3 mmHg were found in 14.0%+/-12.0% (mean +/- standard deviation) of IOP measurements for a symmetric linear regression model, and 8.5%+/-10.6% of IOP measurements for a best-fit linear regression model over 24 hours. CONCLUSIONS: In this group of untreated glaucoma patients, the strength of association between the right and left eye mean IOPs is only moderate. Residual values of > or =3 mmHg were more common using a symmetric model than with a best-fit model. The current method of performing monocular therapeutic trials in glaucoma patients is unreliable, but it may be possible to improve reliability by using several IOP measurements obtained at different times of the day instead of a single office measurement.

Adult↗

PubMed1985

Plasma epinephrine concentration in healthy men: correlation with systolic pressure and rate-pressure product.

Relations among plasma epinephrine, norepinephrine and renin activity and systolic pressure, diastolic pressure, heart rate and the product of heart rate and systolic pressure (rate-pressure product) were evaluated in 31 healthy men whose arterial pressure spanned the range from normal to mildly elevated. Measurements were made during 60 minutes with the patient in the supine position and during 10 minutes of quiet standing. In the supine position, highly significant regressions were found between systolic pressure or rate-pressure product and plasma epinephrine, but not between these variables and norepinephrine or renin activity. A weakly significant correlation was also found between heart rate and norepinephrine. On standing, norepinephrine and epinephrine increased significantly. In this position, rate-pressure product was significantly related by regression analysis only with plasma epinephrine. Weakly significant correlations between systolic pressure and epinephrine and between heart rate and norepinephrine and epinephrine were also found. Plasma renin activity was not significantly correlated with arterial pressure, heart rate or rate-pressure product in either position. These results suggest that plasma epinephrine is a determinant of systolic pressure when postural reflexes are minimized and that epinephrine may participate in control of cardiac work load, as reflected by rate-pressure product in the absence of exercise or definable stress.

Adolescent↗

PubMed1999

Levobupivacaine vs bupivacaine as infiltration anaesthesia in inguinal herniorrhaphy.

We have compared the anaesthetic and analgesic efficacy of levobupivacaine with that of racemic bupivacaine in 66 male patients undergoing ambulatory primary inguinal herniorrhaphy. Patients were allocated randomly in a double-blind manner to local infiltration anaesthesia (0.25% w/v 50 ml) with either racemic bupivacaine (n = 33) or levobupivacaine (n = 33). Scores for intraoperative pain and satisfaction with anaesthesia were recorded, together with perception of postoperative pain and need for supplementary postoperative analgesic medications in the first 48 h after operation. Intraoperative satisfaction with the infiltration anaesthesia was similar, with median scores of 77 (levobupivacaine) and 80 (bupivacaine) (VAS; 100 mm = extremely satisfied). Time averaged postoperative pain scores (48 h) were 8 (levobupivacaine) and 10 (bupivacaine) in the supine position, 13 (levobupivacaine) and 12 (bupivacaine) while rising from the supine position to sitting, and 9 (levobupivacaine) and 13 (bupivacaine) while walking (VAS; 100 mm = worst pain imaginable) (ns). There was no difference in the use of peroral postoperative analgesics between the two groups. We conclude that racemic bupivacaine and its S-enantiomer levobupivacaine had similar efficacy when used as local infiltration anaesthesia in inguinal herniorrhaphy.

Adult↗

PubMed2002

Baroreflexes in vasovagal syncope: two types of abnormal response.

Heart rate changes to hypotensive stimuli (baroreceptor sensitivity [BRS]) and forearm blood flow (FBF) reduction during head-up tilt are mediated by arterial and cardiopulmonary baroreceptors. Regarding baroreflexes in neurocardiogenic syncope (NCS), an apparent variation exists in findings reported in the literature. This may be due to the existence of different types of response. This study included 39 patients with NCS and positive tilt test and 26 normal subjects with negative test. Patients were grouped according to the type of tilt test response (mixed, cardioinhibitory, vasodepressor). BRS was noninvasively assessed in the supine position as an estimate of arterial baroreceptor sensitivity. As an estimate of cardiopulmonary baroreceptor reactivity, FBF was measured by venous occlusion plethysmography in the supine position and every 2.5 minutes during the first 15 minutes of tilt. BRS was related to percent of FBF changes. BRS was impaired in syncopal patients relative to controls (7.2 +/- 0.9 vs 10.4 +/- 0.3 ms/mmHg, P = 0.01), especially in vasodepressive type (4.9 +/- 1.0 ms/mmHg, P = 0.0001). FBF changes during tilt were subnormal in NCS, ascribed to two different patterns: one, characterized by impaired vasoconstriction (FBF during tilt showing < 10% mean reduction relative to baseline, especially in vasodepressive type) and another, characterized by a great variability across time (unstable response, especially in cardioinhibitory type). In controls, BRS was related to the percent of FBF changes after 2.5, 5, and 10 minutes of tilt (P values 0.0001, 0.004, and 0.008). In patients, BRS was uncoupled from FBF changes. In conclusion, baroreflexes in NCS are impaired, unstable, and disorganized. Impairment predominates in the vasodepressive type and instability in the cardioinhibitory. The results of this study are indicative of more than one baroreflex-mediated response types.

Adult↗