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Results for “Supine Position”

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PubMed1992

Relationship of the renin-angiotensin system and systemic arterial pressure to sodium excretion during atrial natriuretic peptide infusion in men.

The goal of this study was to evaluate the relative contribution of the renin-angiotensin system and mean arterial pressure to sodium excretion and urine flow rate during an infusion of atrial natriuretic peptide (ANP) at physiologically relevant doses in humans. Eight normal volunteers were studied during five periods: (1) baseline in the supine position; (2) during an infusion of ANP at physiologic doses (0.01 micrograms/kg/min) in the supine position; (3) during ANP infusion and 60 degrees head-up tilt; (4) during ANP infusion, head-up tilt, and interruption of the renin-angiotensin axis with the angiotensin converting enzyme inhibitor (ACEI) enalaprilat; and (5) in the supine position during ANP infusion and ACEI. Infusion of ANP in the supine posture significantly increased urine flow rate and sodium excretion compared to baseline while mean arterial pressure and plasma renin activity were unchanged. During head-up tilt and ANP infusion, urine flow rate and sodium excretion were no longer significantly elevated over baseline while mean arterial pressure decreased and plasma angiotensin II levels increased. Addition of ACEI caused a marked diminution of urine flow rate and sodium excretion compared to baseline levels despite continued ANP infusion. Although mean arterial pressure after ACEI administration was lower than baseline, it was not significantly different from the non-ACEI head-up tilt state. Placing subjects in the supine position during ANP infusion and ACEI administration increased mean arterial pressure to levels that were no longer different from baseline, but urine flow rate and sodium excretion remained significantly depressed to the same degree as during head-up tilt with ACEI.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed2004

The influence of antegrade scrotal sclerotherapy on the diameter of the spermatic cord veins in men with varicocele.

OBJECTIVE: To assess the influence of antegrade scrotal sclerotherapy on diameter of veins of the pampiniform plexus of the spermatic cord by comparison of the vein diameter before and after the operation in patients with varicocele; to evaluate the rate of recurrence of the disorder after antegrade scrotal sclerotherapy and significance of color Doppler ultrasonography in the diagnosis of varicocele; and to estimate the efficacy of the treatment. MATERIAL AND METHODS: Forty-one patients with various degrees of varicocele treated by antegrade scrotal sclerotherapy were included in the study. The size of the pampiniform plexus of veins of the patients was evaluated clinically during physical examination, and its diameter was measured by color Doppler ultrasonography before and after the operation in the upright and the supine positions during the Valsalva maneuver and without it. RESULTS: After antegrade scrotal sclerotherapy, the diameter of the studied veins was found reliably decreased while examined in all four patient's examining positions, independently of the degree of the preoperative varicocele and recurrence of the disorder. The postoperative decrease of diameter of veins was inversely proportional to the degree of varicocele, i. e. the diameter of veins in the third degree varicocele became most reduced. The recurrence of varicocele after antegrade scrotal sclerotherapy was revealed in 21.9% of the operated patients. The diameter of veins in the recurrent varicocele, assessed by physical examination, and venous blood reflux, detected by ultrasound, reliably decreased in the upright position of patients (p<0.005), whereas in the supine position, diameter of the studied veins remained almost the same as it was before the operation (p=0.9). CONCLUSIONS: After antegrade scrotal sclerotherapy, the diameter of the varicocele vein decrease was statistically significant. It was mostly expressed after the operation in the cases of the third degree varicocele. The postoperative diameter of veins in the recurrent varicocele of the examined patients in the upright position was also reliably smaller than before the operation, but it practically did not differ from the preoperative diameter when the patients were examined in the supine position.

Adolescent↗

PubMed1990

Comparison of genital examination techniques in prepubertal girls.

The results of three separate methods used to examine prepubertal girls are compared and a technique for measuring hymenal orifice diameters from colposcopic photographs is presented. A total of 172 girls who were examined by three techniques during their evaluation in a clinic for suspected child sexual abuse victims were studied. Their ages ranged from 10 months to 11 years with a mean of 5 years, 8 months. The examination techniques used were the supine position with labial separation, the supine position with labial traction, and the knee-chest position. The knee-chest position (98%) and the supine traction method (96%) proved to be superior to the supine separation technique (86%) in opening the vaginal introitus. The largest vertical transhymenal diameters were produced in the knee-chest position, whereas the greatest transverse horizontal spans were generated by the supine traction procedure. Other soft tissue changes were noted but not quantified. A multimethod approach to the examination of the sexually abused child is recommended to take advantage of the strengths of each technique.

Child↗

PubMed1988

Computerized ambulatory esophageal pH monitoring in 50 asymptomatic volunteer subjects. Results and clinical implications.

Fifty asymptomatic volunteer subjects underwent prolonged computerized ambulatory distal esophageal pH monitoring to characterize acid reflux patterns. A bimodal distribution of data, which corresponded to the erect and supine positions, occurred in 45 subjects, and separate mean baseline pH values were noted for the erect and supine positions (pH 6.46 and pH 5.46, respectively, p less than 0.001). At esophageal pH 4, reflux episodes occurred more commonly in the erect position (44 percent) than in the supine position (20 percent). There were also significantly greater numbers of reflux events and longer durations when the pH was below 3 (p less than 0.02) and 4 (p less than 0.001) in the erect compared with the supine position, but prolonged events (more than 10 minutes) occurred in both positions. Postprandial reflux occurred in 78.7 percent of the subjects, with an average of 5.1 episodes. A slight but significant correlation between age and erect reflux was seen (p less than 0.04). In the pH 3 to 5 range, 18 percent of the subjects had acid exposure in excess of the group mean plus 2 standard deviations and 10 percent in excess of the mean plus 3 standard deviations. Overall, a nonnormal distribution of pH data was found with 28 subjects having less than 1.6 percent of their values below pH 4. This finding may represent either the true spectrum of normal acid reflux or a subclinical pathologic state that will become symptomatic over time.

Adult↗

PubMed2003

Dose-volume histogram evaluation of prone and supine patient position in external beam radiotherapy for cervical and endometrial cancer.

BACKGROUND AND PURPOSE: To evaluate the influence of patient positioning on dose-volume histograms of organs at risk in external beam radiotherapy for cervical and endometrial cancer. MATERIALS AND METHODS: In 20 patients scheduled for definitive (7) or postoperative (13) external beam radiotherapy of the pelvis treatment planning CT scans were performed in supine and prone (belly board) positions. After volume definition of target and organs at risk treatment plans were calculated applying the four-field box technique. The dose-volume histograms of organs at risk were compared. RESULTS: Radiotherapy in prone position causes a reduction of the bladder portion (mean 15%, p<0.001) and an increase of the rectum portion (mean 11%, p<0.001) within the 90% isodose. A reduction of the bowel portion could only be observed in postoperatively treated patients (mean 13%, p<0.001). In definitive radiotherapy the target volume increases in supine position (mean 7%, p=0.02) due to an anterior tumour/uterus movement, so that bowel portions within the 90% isodose are similar. The bladder filling correlates with a reduction of bladder and bowel (postoperatively treated patients) dose. CONCLUSIONS: External beam radiotherapy of the pelvis should be performed in prone position in postoperative patients because of best bowel protection. Considering the additional HDR brachytherapy rectum protection takes the highest priority in definitive treatment-the requirements are best met in supine position. An adequate bladder filling is important to reduce the irradiated bladder and bowel volumes.

Endometrial Neoplasms↗

PubMed1998

Auditory arousal thresholds are higher when infants sleep in the prone position.

OBJECTIVE: To evaluate the possibility that infants sleeping in the prone position have higher arousal thresholds to auditory challenges than when sleeping in the supine position. STUDY DESIGN: Polygraphic recordings were performed for 1 night in 25 healthy infants with a median age of 9 weeks. The infants were exposed to white noises of increasing intensities while sleeping successively in the prone and supine positions, or vice versa. Arousal thresholds were defined by the auditory stimuli needed to induce polygraphic arousals. RESULTS: Three infants were excluded from the study because they awoke while their position was being changed. For the 22 infants included in the analysis, more intense auditory stimuli were needed to arouse the infants in the prone position than those in the supine body position (p = 0.011). Arousal thresholds were higher in the prone than in the supine position in 15 infants; unchanged in 4 infants; and lower in the prone position in 3 infants (p = 0.007). CONCLUSIONS: Infants show higher arousal thresholds to auditory challenges when sleeping in the prone position than when sleeping in the supine position. The finding could be relevant to mechanisms concerned with the reported association between sudden deaths and the prone sleeping position in infants.

Auditory Threshold↗

PubMed1992

Tidal breath flow-volume curves in obstructive sleep apnea.

Because of the gravitational position during sleep and the associated relaxed state, we hypothesized that passive expiration in the supine position might reflect upper airway pathophysiology in obstructive sleep apnea (OSA). We prospectively enrolled and tested 92 subjects with several clinical conditions. Maximal comfort and relaxation during expiration was achieved by connecting subjects to a ventilator via a mouthpiece. An initial respiratory rate of 16 breaths/min and tidal volume of 10 ml/kg were selected. Fine adjustments were then made to achieve maximal subject relaxation. Using this method, we obtained reproducible tidal breath flow-volume curves (TBFVC). Testing was performed in both sitting and supine positions. Standard pulmonary function tests, including spirometry and lung volume measurements, were also obtained in both sitting and supine positions. Of 86 patients who could be evaluated, 12 (60%) of 20 subjects with documented OSA (respiratory disturbance index: mean, 64.8; range, 10 to 120.5) demonstrated a positional change in the terminal portion of the TBFVC; 10 (32%) of 31 with a history of snoring also tested positive, but only three (9%) of 35 subjects with no OSA, by polysomnography (n = 8) or questionnaire (n = 27), demonstrated such a positional change. This positional change in TBFVC, which was significantly more frequent in subjects with OSA, could not be attributed to any measurable pulmonary function abnormality or body mass index. We believe this positional change in TBFVC reflects upper airway functional narrowing induced by assumption of supine position and decreasing airflow rates.

Female↗

PubMed2006

Unloading reaction to electrical stimulation at neutral and supinated ankle positions.

An unloading reaction has been characterized as a modified flexor reflex (FR), in which the standing subjects decrease the load on the stimulated foot and increase the load on the contralateral side, but, without withdrawal of the stimulated foot. Different behavioral circumstances have been shown to modulate this reflex. It is not known whether unloading reactions can be modulated with a loaded supinated ankle position, which, in excess, may result in an ankle sprain injury. Since ankle sprain depends on the load applied to a supinated foot, our premise is that unloading reactions may protect the ankle from a sprain injury. Therefore, this study investigated how the unloading reactions were modulated during a loaded supinated ankle condition. We delivered non-nociceptive and nociceptive electrical stimulations on the lateral aspect of the ankle in standing subjects with the foot in neutral and in a supinated position. The magnitude and latencies of reflex responses were registered using kinetic and kinematic analyses and subsequently compared among the conditions. The analysis demonstrated greater reactions for the supinated ankle condition. The individuals also moved their whole body downwards and shifted the body weight to the non-stimulated foot. Therefore, this study suggested that a modified type of the classic flexion reflex, i.e., unloading reaction, may be used as a strategy to unload a supinated ankle and potentially minimize the risk of ankle sprain injuries.

Adult↗

PubMed1998

Prone position may increase temperature around the head of the infant.

Recommendations to adopt the supine position were followed by a dramatic decrease of SIDS. But no explanation has been given for the association between SIDS and the prone position nor for its decrease in the supine position. We report data on an infant and a mannequin demonstrating an increase in temperature around the head in the prone position. A 4-month-old boy presented an acute life-threatening event related to temperature after febrile otitis despite treatment: 40.5 degrees C, heart rate 280 bpm with circulatory failure and cardiorespiratory arrest requiring resuscitation. There were no seizures. Blood and CSF cultures were negative. The course under antibiotics was favourable. On d 3, we measured temperature at several sites on and around the heat. Temperatures were higher in the prone than in the supine position in pericephalic areas: +1 degrees C (supracephalic), +2.5 degrees C (peritemporal), and +3.5 degrees C (submandibular). In a thermoregulated room, we used a mechanically ventilated mannequin of an infant. The prone position was also associated with an increase in temperature around the head: +3.3 degrees C (supracephalic), +1.8 degrees C (peritemporal), and +1.1 degrees C (submandibular). Changing from the supine to prone position thus increased temperature around the head (infant and mannequin). To our knowledge, this has not been reported before. SIDS is related to factors modifying temperature status and environment. Furthermore, evacuation of heat is mandatory for an infant. We think the increase in temperature around the head in the prone position is due to the absence of convective fluxes, and speculate it could impair thermolysis.

Body Temperature↗

PubMed2001

Position for newborn sleep: associations with parents' perceptions of their nursery experience.

BACKGROUND: In the United States, sudden infant death syndrome is the leading cause of death among infants between the ages of 1 and 12 months. Although its etiology is unclear, infants who sleep in the prone or side positions are at increased risk. The objective of this study was to examine the association between the perceptions of inner city parents about teaching and modeling during the postpartum period of infant sleeping position, and their choice of sleeping position for their infants. METHODS: A convenience sample of parents of 100 healthy infants who came for the 2-week well-child visit at an urban primary care center were invited to complete a questionnaire and to report on the position in which infants were placed for sleep. RESULTS: Forty-two percent of parents reported that they usually placed their infants in the supine position for sleep; 26 percent placed their infants to sleep in the prone position at least some of the time. Parents who reported being told by a doctor or a nurse to have their infants sleep in the supine position were more likely to choose that position. Similarly, those who reported seeing their infants placed to sleep exclusively in the supine position in the hospital were also more likely usually to choose that position. Parents who reported that they both were told by a doctor or a nurse to put their infants to sleep in the supine position and reported seeing their infants exclusively placed that way in the nursery were the most likely usually to choose that position for their infants to sleep. CONCLUSIONS: Perceptions by parents of instructions from a doctor or a nurse of the position in which the infants were placed in the nursery were associated with the position parents reported placing their infants to sleep at home. Efforts to promote the supine sleeping position in the inner-city setting should address both practices and education provided to parents in the nursery during the postpartum hospital stay and should be sufficiently powerful to align their perceptions of the postpartum experience with current American Academy of Pediatrics recommendations.

Adolescent↗

PubMed2002

Quality of diet, body position, and time after feeding influence behavioral states in low birth weight infants.

The effects of variations in carbohydrate and fat intake and body position on behavioral activity states were evaluated in 64 healthy, growing low birth weight infants (birth weight, 750-1600 g). The infants, enrolled in a prospective, randomized, double-blind, controlled study of effects of quality of dietary energy, were fed one of the five formulas. These formulas contained fixed intakes of protein (4 g/kg per day) but different intakes of carbohydrate (9.1 to 20.4 g/kg per day) and fat (4.3 to 9.5 g/kg per day). Six-hour daytime sleep studies were performed at 2-wk intervals from time of full enteral intake until discharge (mean postconceptional age at first study, 33.2 +/- 1.8 wk). Infants were randomly assigned to the prone or supine position for the first 3-h postprandial period; the position was reversed during the second 3 h. Behavioral activity state, i.e. quiet sleep (QS), active sleep, indeterminate sleep, awake, or crying was coded each minute throughout the postprandial period. The overall incidence of QS was almost double in the prone position versus the supine (p < 0.0001). In contrast, the probability of being in either of the two wakeful states (awake and crying) was increased when infants were placed in supine position (p < 0.0001). Increased likelihood of being in QS while prone was found only during the 30 min after and before feeding in a 150-min prandial cycle. In contrast, increased amounts of awake and crying in supine position were observed throughout the feeding interval. As carbohydrate intake increased, time spent in QS in supine position increased (from 8.6% to 12.5%, p < 0.02), and a trend in the same direction was noted for the prone position (p = 0.06). However, during postprandial minutes 10-100, when QS is likely to be entrained by the nutrient intake, enhancement of QS was found in the prone position only (p < 0.02). Carbohydrate intake influences the total time spent and the distribution of behavioral activity states within the postprandial period in low birth weight infants. The effect of nutrient intake on sleep profile is dependent on body position and time after feed. Mechanistic hypotheses relating sudden infant death syndrome to sleeping position may need to take these observations into account.

Dietary Carbohydrates↗

PubMed2005

[Evaluation of a new method for detection of obstructive disease in children asthma: the negative expiratory pressure (NEP)].

INTRODUCTION: To take in charge of an asthmatic child it is necessary to evaluate the lung function. METHODS: In this study, the Negative Expiratory Pressure (NEP) has been used for the first time in children with asthma. After lung spirometry by plethysmography, we have used the NEP to assess the prevalence of expiratory flow limitation (FL) during resting breath in 27 asthmatic children (mean age: 11 +/- 2,5 years) 3-4 days after a crisis in both sitting and supine positions. RESULTS: All the children presented an obstructive defect (FEV 1: 63 +/- 13% med) and a dynamic hyperinflation (FRC: 128 +/- 25% med). According to the NEP, 11 children presented an expiratory flow limitation (FL). Asthma was more severe in the FL than in non-FL children (GINA 2002 classification). Among the 11 FL children, 5 were FL in both sitting and supine position and 6 only in supine. Nine of the 27 children were FL with the conventional method. NEP seems a more accurate method to assess the clinical gravity of asthma than FEV 1. The reduction of FRC in the supine position probably explains the greater incidence of FL in supine position. CONCLUSION: Because of its easy execution, NEP seems to be well adapted for children. Links between FL detected by NEP and clinical signs of asthma has to be assessed by furthers studies including more patients.

Adolescent↗

PubMed2000

Influence of different supine body positions on blood pressure: consequences for night blood pressure/dipper-status.

OBJECTIVES: To investigate the influence of different supine body positions on blood pressure measured by an ambulatory device. DESIGN AND METHODS: Twenty hypertensive and 20 normotensive subjects of a tertiary hospital outpatient clinic participated. Blood pressure was measured with an ambulatory blood pressure device while lying in the back, left side, right side and abdominal positions. The distance between the antecubital fossa and sternum was measured in all four body positions. An expected blood pressure difference between the arm of measurement and the right atrium (i.e. the midsternum) was calculated for the different body positions. RESULTS: When blood pressure was measured in side position at the left arm in hypertensive subjects, the mean systolic and diastolic blood pressure differences (+/- SD) between the left arm in the lower position and in back position at the same arm were +5/+4 (8/6) mmHg. These differences were -14/-17 (6/4) mmHg for the left arm lying above heart level in side position. Values of the right arm in hypertensives and the measurement at both arms in normotensive subjects yielded similar differences. CONCLUSIONS: Body and arm position can both significantly influence the ambulatory blood pressure and therefore the day-night difference. This comprises one of the main reasons for the moderate individual reproducibility of the blood pressure fall at night.

Adult↗

PubMed1980

Evidences supporting an increased sympathetic tone and reactivity in a subgroup of patients with essential hypertension.

Several experimental evidences have shown that, under standarized conditions, circulating catecholamines (CA) or norepinephrine (NE) levels can be used as a valid index of the sympatho-adrenal activity in animal and man. This approach in the study of hypertensive patients has permitted to uncover that about 50% of patients with labile hypertension and about 30% of patients with stable hypertension had elevated CA levels at rest for 20 minutes in the supine position. The increased CA levels were mainly due to a rise in NE in stable hypertension and to a rise in epinephrine (E) in labile hypertension. On the basis of circulating CA levels, the hypertensive patients were divided into hyperadrenergic (CA levels above normal range) and normoadrenergic (CA levels within the normal range) subgroups. The hyperadrenergic labile or stable hypertensive subgroups were found to be also characterized by an enhanced CA or NE increase in response to change in position from supine to standing, by a faster heart rate and by an increased myocardial contractility, while these parameters were normal in the normoadrenergic subgroups. These findings support therefore the existence of an increased sympathetic tone and reactivity in association with hyperkinetic cardiac functions in an important population of hypertensive patients. In response to two weeks treatment with beta-blockers (either propranolol or metoprolol) hyperadrenergic stable hypertensive patients were found to be more responsive to this therapy than normoadrenergic patients although both groups had the same initial blood pressure. Moreover, this treatment lowered basal NE or CA levels and restored the enhanced CA or NE response to change in position toward normal in hyperadrenergic patients while it did not modify significantly circulating supine or standing CA and NE in normoadrenergic patients. These findings strongly support a participation of the sympathetic system in the maintenance of an elevated blood pressure in hyperadrenergic patients and raise the possibility of using a more rational approach in the therapy of hypertension.

Adult↗

PubMed2006

Barriers to following the supine sleep recommendation among mothers at four centers for the Women, Infants, and Children Program.

OBJECTIVES: The risk for sudden infant death syndrome in black infants is twice that of white infants, and their parents are less likely to place them in the supine position for sleep. We previously identified barriers for parents to follow recommendations for sleep position. Our objective with this study was to quantify these barriers, particularly among low-income, primarily black mothers. DESIGN/METHODS: We conducted face-to-face interviews with 671 mothers, 64% of whom were black, who attended Women, Infants, and Children Program centers in Boston, Massachusetts, Dallas, Texas, Los Angeles, California, and New Haven, Connecticut. We used univariate analyses to quantify factors that were associated with choice of sleeping position and multivariate logistic regression to calculate adjusted odds ratios for the 2 outcome variables: "ever" (meaning usually, sometimes, or last night) put infant in the prone position for sleep and "usually" put infant in the supine position to sleep. RESULTS: Fifty-nine percent of mothers reported supine, 25% side, 15% prone, and 1% other as the usual position. Thirty-four percent reported that they ever placed infants in the prone position. Seventy-two percent said that a nurse, 53% a doctor, and 38% a female friend or relative provided source of advice. Only 42% reported that a nurse, only 36% a doctor, and only 15% a female friend or relative recommended the supine position for sleep. When a female friend or relative recommended the prone position, mothers were more likely ever to place their infants in the prone position and less likely usually to choose supine compared with those who received no advice from friends or relatives. When a doctor or a nurse recommended a nonsupine position, the mothers were less likely to choose supine compared with those who received no advice from a doctor or a nurse. Mothers who trusted the opinion of a doctor or a nurse about infant sleeping position were more likely to place their infants in the supine position. Half of the mothers believed that infants were more likely to choke when supine, and they were less likely to place their infants supine. Mothers who believed that infants are more comfortable in the prone position (36%) were more likely to place their infants prone. Twenty-nine percent believed that having their infants sleep with an adult helps prevent sudden infant death syndrome, and only 43% believed that sudden infant death syndrome is related to sleeping position. CONCLUSIONS: We identified specific barriers to placing infants in the supine position for sleep (lack of or wrong advice, lack of trust in providers, knowledge and concerns about safety and comfort) in low-income, primarily black mothers that should be considered when designing interventions to get more infants onto their back for sleep.

Adult↗

PubMed2001

The diagnostic effect from axial loading of the lumbar spine during computed tomography and magnetic resonance imaging in patients with degenerative disorders.

STUDY DESIGN: Patients with low back pain, sciatica, and neurogenic claudication were observed during computed tomographic myelography or magnetic resonance imaging in psoas-relaxed position and axially compressed supine position of the lumbar spine. OBJECTIVE: To estimate the clinical value of axially loaded imaging in patients with degenerative disorders of the lumbar spine. SUMMARY OF BACKGROUND DATA: Computed tomography and magnetic resonance imaging still are performed with the lumbar spine in a supine relaxed position, which results in unloading of the spine and enlargement of the canal. METHODS: A device for axial loading of the lumbar spine in computed tomography and magnetic resonance imaging was used. Altogether, 172 patients were examined in psoas-relaxed position and axially compressed supine position of the lumbar spine: 50 patients with computed tomographic myelography and 122 patients with magnetic resonance imaging. If a significant decrease (>15 mm2) in the dural sac cross-sectional area to values smaller than 75 mm2 (the borderline value for stenosis) was found during examination in axial loading, or if a suspected disc herniation, narrow lateral recess, narrow intervertebral foramen, or intraspinal synovial cyst changed to being obvious at the axial loading examination, this was regarded as additional information important for the treatment. RESULTS: Additional valuable information was found in 50 of 172 patients (29%) during examination in axial loading. In the different diagnostic groups, additional valuable information was found in 69% of the patients with neurogenic claudication, in 14% of the patients with sciatica, and in 0% of the patients with low back pain. The percentage of additional valuable information increased to 50% in the patients with sciatica, if recommended inclusion criteria for examinations in axial loading were used. A narrowing of the lateral recess causing compression of the nerve root was found at 42 levels in 35 patients at axial loading. CONCLUSION: According to the study results, axially loaded imaging adds frequent additional valuable information, as compared with conventional imaging methods, especially in patients with neurogenic claudication, but also in patients with sciatica if defined inclusion criteria are used.

Adult↗

PubMed2003

Propofol pharmacokinetics in a dwarfism patient.

Pharmacokinetic information is important to control anesthetic depth. However, there are few available pharmacokinetic data of propofol in dwarfism patients. We anesthetized a dwarfism patient who underwent spinal decompression, and investigated the pharmacokinetics of propofol. The patient was a 40-year-old man suffering from muscle weakness and numbness in the arms. The operation consisted of two stages; anterior approach in the supine position and posterior approach in the prone position. We also obtained arterial blood for pharmacokinetic analysis. Distribution volume at steady-state and clearance in the supine position was 180 and 0.92 l min- 1, respectively, and in the prone position 127 and 0.74 l min- 1, respectively, in spite of a continuous infusion of dopamine. The data in the supine position were well predicted by Gepts' parameters (used in Diprifusor Zeneca Ltd, Cheshire, UK), which means the target-controlled infusion (TCI) technique can be available in the supine position, while attention is necessary to avoid overdosing when a patient is placed in the prone position.

Adult↗

PubMed1993

Regulation of 18-oxocortisol and 18-hydroxycortisol by the renin-angiotensin system and ACTH in man.

Based on urinary excretion studies the secretion of the cortisol derivatives, 18-oxocortisol and 18-hydroxycortisol are believed to be regulated by ACTH and to a lesser degree by the renin-angiotensin system. Plasma concentrations of 18-oxocortisol and 18-hydroxycortisol were measured during the simultaneous activation of the renin-angiotensin system and inhibition of ACTH secretion. Five healthy male subjects consuming a sodium diet ad libitum were studied. Blood was drawn at 0800 h after 1 h in the supine position. In the first set of experiments, the subjects remained in the supine position from 0800 to 1000 h with or without the oral administration of 2 mg dexamethasone at 0800 h. In the second set of experiments the subjects were placed in the upright position after drawing the 0800 h sample. The subjects were studied with and without dexamethasone administered at 0800 h. Blood was drawn again at 1000 h. Plasma levels of 18-oxocortisol, 18-hydroxycortisol, ACTH, plasma renin activity (PRA), cortisol, aldosterone and 18-hydroxycorticosterone were measured by radioimmunoassay. None of these parameters changed during the 2 h in the supine position. 18-Oxocortisol, 18-hydroxycortisol, aldosterone, 18-hydroxycorticosterone and PRA increased, but ACTH and cortisol did not change when the subjects were placed in the upright position. After dexamethasone administration, 18-oxocortisol, 18-hydroxycortisol, cortisol, aldosterone and 18-hydroxycorticosterone decreased in the supine position and no increase occurred in 18-oxocortisol, 18-hydroxycortisol and 18-hydroxycorticosterone in the upright position. PRA and aldosterone increased and ACTH and cortisol decreased in these subjects. 18-Oxocortisol and 18-hydroxycortisol were more dependent on ACTH regulation and less on the renin-angiotensin system than aldosterone.

18-Hydroxycorticosterone↗