[Collapse in a pregnant woman in supine position (supine hypotensive syndrome) as a possible cause of fetal death].
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Eighty-seven pregnant mothers undergoing elective Caesarean section were randomly allocated either to the full left lateral position (n = 45) or to the supine position with 12 degrees left lateral tilt (n = 42) after a combined spinal-epidural (CSE) in the sitting position and an initial 2 min in the full right lateral position. Fewer mothers were hypotensive while in the study position [29 (64%) in lateral group vs. 38 (90%) in the tilted supine group; p = 0.03]. Mothers in the lateral group tended to become hypotensive after turning them back to the tilted supine position immediately before surgery; hence the number of mothers who were hypotensive from the insertion of the CSE until delivery were similar [36 (80%) vs. 38 (90%)]. Mothers in the lateral group needed a lower dose of ephedrine to treat their hypotension while in their study position (median (interquartile range [range]) 6 (0-12 [0-36]) mg vs. 12 (6-18 [0-36]) mg, respectively; p = 0.04) but ephedrine requirements were similar overall (12 (6-12 [0-36]) mg vs. 12 (6-18 [0-36]) mg), respectively. The full left lateral position reduces the incidence of early hypotension compared with the tilted supine position with tilt, and makes it easier to treat.
The effect of body position (supine v prone) on energy expenditure and behavior of 42 healthy low birth weight (920 to 1,760 g) infants was evaluated in 66 studies. Each infant was randomly assigned to the supine or prone position for the first three-hour epoch; the position was reversed for the second three-hour epoch. The difference in energy expenditure and the percentage of time in active sleep, quiet sleep, and wakefulness between the two positions was computed. The median difference (supine minus prone) in overall energy expenditure between positions was +3.1 kcal/kg/d (interquartile range 0.6 to 6.5; P less than .001). When only periods of active sleep were analyzed, the median difference in energy expenditure remained significant, the supine position being higher than prone by +2.6 kcal/kg/d (interquartile range 0.1 to 4.8; P less than .001). In the supine position, the time awake was 5.7% higher (interquartile range 1.8 to 17.4; P less than .001) than in the prone position. The percentage of time in active sleep was not significantly different between the positions, hence quiet sleep decreased in the supine position. In summary, when low birth weight infants are changed from the supine to the prone position, energy expenditure decreases, time spent in quiet sleep increases, and time spent awake decreases. These data suggest that prone is the position of choice for the low birth weight infant.
BACKGROUND: Class III obese patients have altered respiratory mechanics, which are further impaired in the supine position. The authors explored the hypothesis that preoxygenation in the 25 degrees head-up position allows a greater safety margin for induction of anesthesia than the supine position. METHODS: A randomized controlled trial measured oxygen saturation and the desaturation safety period after 3 min of preoxygenation in 42 consecutive (male:female 13:29) severely obese (body mass index > 40 kg/m) patients who were undergoing laparoscopic adjustable gastric band surgery and were randomly assigned to the supine position or the 25 degrees head-up position. Serial arterial blood gases were taken before and after preoxygenation and 90 s after induction. After induction, ventilation was delayed until blood oxygen saturation reached 92%, and this desaturation safety period was recorded. RESULTS: The mean body mass indexes for the supine and 25 degrees head-up groups were 47.3 and 44.9 kg/m, respectively (P = 0.18). The group randomly assigned to the 25 degrees head-up position achieved higher preinduction oxygen tensions (442 +/- 104 vs. 360 +/- 99 mmHg; P = 0.012) and took longer to reach an oxygen saturation of 92% (201 +/- 55 vs. 155 +/- 69 s; P = 0.023). There was a strong positive correlation between the induction oxygen tension achieved and the time to reach an oxygen saturation of 92% (r = 0.51, P = 0.001). There were no adverse events associated with the study. CONCLUSION: Preoxygenation in the 25 degrees head-up position achieves 23% higher oxygen tensions, allowing a clinically significant increase in the desaturation safety period--greater time for intubation and airway control. Induction in the 25 degrees head-up position may provide a greater safety margin for airway control.
PURPOSE: To map B(0) distortions throughout the monkey brain in the two positions commonly used for NMR studies (the prone sphinx position and the supine position) in order to test the hypothesis that B(0) homogeneity in the sphinx position is significantly improved as compared to the supine position. MATERIALS AND METHODS: Three macaque monkeys were installed in the two positions in a 3T whole-body MR system without shim correction. B(0) maps were acquired using a 3D gradient double-echo sequence, and field dispersion throughout the brain was quantified. In addition, field maps and localized (1)H spectra were acquired after first-order shimming was performed. RESULTS: The field maps collected in the three animals were highly reproducible. B(0) dispersion throughout the brain was typically two to three times greater in the supine position than in the sphinx position. Although first-order shimming proved relatively more efficient in the supine position, B(0) dispersion still remained greater in the supine than in the sphinx position. These findings can be explained by the thickness of outer brain tissues. CONCLUSION: This work demonstrates that the sphinx position is highly favorable in terms of B(0) homogeneity. It should prove useful for NMR exploration of the monkey brain, particularly at high fields where B(0) inhomogeneity associated with susceptibility artifacts is increased.
BACKGROUND: It is possible that obesity could lead to pulmonary restriction with decreasing lung volumes. However, controversies about this restriction and its etiology still exist. Thus, the purpose of this report was to evaluate the effects of body weigh excess on spirometry, on three different body positions, evaluated by Body Mass Index (BMI), percentage of fatness and the ratio of abdominal girth to hip breadth (AG/HB). METHODS: Forty-six sedentary volunteers, with ages between 20 and 40 years, were studied and distributed on five groups, based on BMI. Skin fold thickness and ratio of abdominal girth to hip breadth (AG/HB) of the volunteers were measured. FVC, FEV1 and ratio of FEV1 to FVC were measured on three different body positions--sitting, supine and orthostatic positions. RESULTS: Comparing the values measured and predicted between the groups, no difference was detected. Comparing body positions, the supine position shows lower values than sitting and orthostatic positions (p<0.05). Associations between CVF, VEF1 e VEF1/CVF values and BMI, percentage of fatness and ratio of AG/HB were not found. CONCLUSIONS: Spirometric values from obese people are into normality range and decrease on the supine position.
We evaluated the influence of positioning, and particularly a containing position in a hammock compared with the supine position, on the respiration of the newborn. Recordings of the transcutaneous oxygen level of 40 preterm babies and 10 full-term babies placed in their incubators alternately in the two positions have been analyzed. We found no significant differences between the means of the oxymetric indexes in the hammock and in the supine position, even when the babies had different gestational ages and birth weights. The advantages of the containing position for the neuromotor and relational development of the newborn in the first year of life in comparison with the effects of supine placement, which should be avoided as much as possible in the premature, are pointed out.
PURPOSE: The authors compared the supine and standing positions for lymphoscintigraphy in breast cancer patients to identify any changes in the number of affected lymph nodes detected and the quality of images. METHODS: Twenty-three patients were examined using lymphoscintigraphy in both positions. Sequential supine, standing, and supine oblique images were acquired in each patient. RESULTS: The number of lymph nodes detected or the quality of the images acquired was improved in 20 of the 23 patients in the standing position compared with the supine position. The remaining three patients' images were judged to be equal in lymph node number and image quality in both positions. CONCLUSIONS: Lymphoscintigraphy in patients with breast cancer appears to be more sensitive in the standing than in the supine position.
Ventilation and pulmonary perfusion scintigraphy were performed in 7 patients in whom postural change from the sitting position to the supine position decreased partial oxygen pressure in arteries (PaO2) by 15 mmHg or more. Six of these 7 patients were obese. Five patients had organic pulmonary disease or space occupying lesions of the liver. On lateral supine-position images taken by using the continuous inhalation method for 81mKr ventilation scintigraphy, ventilation was reduced in the dorsal area corresponding to a gravity-dependent area, but on pulmonary perfusion scintigrams, there were no marked changes compared to normal adults. The mismatch of ventilation to perfusion may have caused hypoxemia. Reduced ventilation was correlated with reduced PaO2. The distribution of 81mKr bolus gas inhalation suggested closure of the airway in the dorsal area at functional residual capacity (FRC), which means the resting expiratory level, in the supine position.
Manual repositioning of patients by nursing staff is a recognised technique for preventing pressure ulcer formation. The 30 degree tilt is a method of positioning patients that, in the laboratory setting, reduced the contact pressure between the patient and the support surface. A randomised controlled trial was used to examine the effects of the 30 degree tilt position in reducing the incidence of non-blanching erythema (i.e. established pressure damage) in a hospital inpatient population (n=23) when compared to the use of the 90 degree lateral and supine position (n=23). The primary outcome of the trial was the incidence of pressure damage, defined as non-blanching erythema. In this study no subject developed pressure damage that presented with visible breaks in the epidermis, but all damage was restricted to areas of non-blanching erythema (five of the 39 subjects who completed the study exhibited such injury). The main findings of this study were that patient positioning using the 30 degree tilt method did not reduce the incidence of pressure damage compared with either the 90 degree lateral or supine positions. This study also investigated the feasibility of using the 30 degree tilt position with medical inpatients; it found that 78% of subjects experienced difficulty in adopting and maintaining the position. This finding seriously questions the practicality of using the 30 degree tilt method with a predominantly ill population.
OBJECTIVE: Supine positioning of the patient taking into account - the demands of anesthesia in an emergency requiring intubation, - minimal time for sterile draping, - patient position can be adjusted by the assistants, - easier implant positioning due to the supine position. Reduction of operative trauma with earlier mobilization and shorter rehabilitation time compared with conventional technique. Application of standard instruments and implants. INDICATIONS: Coxarthroses, necroses of the femoral head. CONTRAINDICATIONS: For the "gynecologic position": - hip joint arthrodesis of the contralateral side. - flexion of the contralateral side < 20 degrees . For minimally invasive total hip replacement: - severe anatomic deformities. - revision operations. POSITIONING AND SURGICAL TECHNIQUE: Supine position of the patient with the contralateral leg held at approximately 30 degrees flexion in a gynecologic footrest attached to the operating table. Leg support that can be lowered for the leg being operated on. Minimally invasive anterolateral approach without dissection of muscles or tendons. Resection of the femoral neck and removal of the femoral head. Preparation of the acetabulum and implantation of the cup. Hyperextension of the leg by lowering the leg support with subsequent adduction and external rotation beneath the elevated contralateral leg. Preparation of the femur and implantation of the stem with subsequent repositioning and wound closure. RESULTS: 185 total hip replacements were performed with this positioning and surgical technique from September 2004 to June 2005. The first 108 minimally invasive procedures were compared with 117 conventional procedures. The patients operated in minimally invasive technique generally did better in terms of operating time, blood loss, use of analgesics, rehabilitation time, and functional outcomes. In seven patients, shaft fissures occurred within the first 3 months due to too abrupt intraoperative dislocation of the leg (learning curve!), but were all treated by application of cerclage and healed uneventfully.
BACKGROUND AND OBJECTIVE: Prevention of the supine position has for decades been a well known treatment option in positional obstructive sleep apnea. It was the aim of this study to test the efficacy of a recently patented commercially available supine position preventing vest. PATIENTS AND METHODS: The vest is made of linen tissue with a half cylindrical piece of hard foam in its dorsal part. 12 male patients slightly overweight (body mass index 26.5 +/- 2.6 kg/m(2)) and 55.8 +/- 11.6 years old were investigated polysomnographically prospectively. RESULTS: The pretherapeutical respiratory-disturbance index (RDI) was 26.7+/-11.9/h increasing to 39.3+/-16.1/h in the supine position. When using the vest, patients no longer slept on their back and the RDI dropped to 7.6 +/- 5.1/h (p < 0.005). Total sleep time at an oxygen saturation below 90 % was reduced from 11.7 +/- 11.3 % to 1.5 +/- 2.1 %. 9 patients (75 %) were cured (RDI < 10/h and RDI reduction > 50 %), 2 patients (17 %) improved (RDI reduction > 50 %) and only the oldest patient (76 years old) remained unchanged. Even though snoring decreased from 180 +/- 125 minutes to 110 +/- 52 minutes, an increase was observed in 30 % of the patients. Sleep quality and structure did not change considerably. CONCLUSION: The supine position prevention vest is a safe and simple treatment alternative of high efficacy in positional sleep apnea. As a complete remission cannot be predicted, polygraphic or polysomnographic controls are necessary.
The intraoperative blood loss of 40 uncomplicated primary total hip arthroplasties was studied in a retrospective, matched pair analysis. Half of them were implanted in the supine position after complete excision of the capsule and the other half in the lateral position with preservation of the capsule. The patients were matched for mono- or bilateral procedure. Only one surgeon carried out the operations using the same operative technique and identical prosthesis in both groups. The intraoperative blood loss associated with the lateral position and preservation of the capsule averaged 830 ml and was significantly lower (P = 0.01) than 1165 ml with the supine position and complete capsulectomy. Thus, the intraoperative blood loss can be significantly reduced in primary total hip arthroplasty by choosing the lateral position and preserving the capsule.
This study aimed to see if gas trapping or ventilation inhomogeneity during tidal breathing increases in young asthmatic subjects when recumbent over a period of 1 hr. Ten asthmatic children and teenagers and 12 control subjects performed tidal breathing multiple-breath N(2)-washout in the sitting position and immediately, 30 min, and 60 min after assuming the supine position. The asthma group also performed the same lung function tests on another day, but then remained in the sitting position throughout. When assuming the supine position, both groups showed significant falls in vital capacity (4-8%) and in functional residual capacity (FRC) (>20%). Gas trapping increased significantly after 30 and 60 min in the supine position only in the asthma group, but other indices of ventilation inhomogeneity did not change with body position. When in the supine position, the trapped gas volume was on average 10% of FRC in the asthma group, which was twice as much as when sitting and three times higher than in supine control subjects. It is concluded that assuming the supine position leads to increased gas trapping in young asthmatics but not in healthy subjects; this could be one of several mechanisms that contribute to nocturnal worsening of asthma.
BACKGROUND: In Japan, haemodialysis (HD) is usually performed with patients in the supine position. However, the effects of changing posture on major blood components have not been investigated in HD patients. It is possible that several fluid components change rapidly when patients change from the upright to the supine position. We therefore investigated the effects of posture on blood component analysis. METHODS: A first blood sample was taken from 10 HD patients 5 min after they adopted a supine position; HD was begun immediately after sampling. Additional blood samples were collected 15 and 30 min later while patients remained in the supine position. On an alternate day, blood samples were taken from these same patients in the supine position, but not during HD. The same procedure was performed in 10 healthy volunteers. RESULTS: Haematocrit significantly decreased in patients undergoing HD at 15 and 30 min into the HD session. Similar decreases were observed in HD patients not undergoing HD and in normal control subjects. Haematocrit changes at 15 min were not significantly different between the three groups. Serum albumin concentrations decreased in the same way as haematocrit. Consequently, the reductions in haematocrit and albumin concentrations in HD patients during the HD session were not attributable to the HD procedure or to end-stage renal disease, but rather were due to the supine position and consequent haemodilution caused by redistribution of water from the extra- to the intravascular space. Finally, WBC counts decreased significantly at 15 min in both HD patient groups and in normal controls. The relative decrease at 15 min was significantly greater in HD patients undergoing HD (61.4% of baseline) than in those not undergoing HD (88.0%) or in normal controls (94.7%). These differences were probably due to previously reported WBC sequestration in the lungs during the early phase of HD. CONCLUSIONS: This study suggests that the change from the upright to the supine positions during HD causes changes in blood components that are critical for quality control determinations.
Twelve nephrectomized patients were examined by computed tomography in prone and supine position. The distances necessary for irradiation planning were measured in order to estimate which position is more favorable for irradiation. The advantages of prone position in comparison to supine position seem uncertain and do not outweigh its disadvantages.
Studies were undertaken on seven adult female buffaloes (Bubalus bubalis) premedicated with triflupromazine hydrochloride (0.3 mg/kg) and chloral hydrate (30 mg/kg). Anaesthesia was induced with thiopentone sodium (10 mg/kg) and animals were kept under intermittent positive pressure ventilation. Measurements were made for 30 min in the lateral position, for 20 min in the supine position and subsequently for 40 min again in the lateral position. Regurgitation during anaesthesia was avoided by evacuation of the rumen by rumenotomy two days prior to the experiment. When animals were in the lateral position there were minimal changes in arterial pressure and heart rate but central venous pressure rose. These changes were related to intermittent positive pressure ventilation. In the supine position, increase in heart rate (28%) was associated with profound hypotension (56%) and decrease in central venous pressure (171%) in these animals. There was a fall in venous oxygen tension and a marked increase (91%) in oxygen extraction ratio. Restoration to the lateral position ameliorated all these changes rapidly. It was suggested that a 'low pressure-low flow' circulatory state exists in anaesthetised adult buffaloes in the supine position.
PURPOSE: Intraocular pressure is higher in older than younger subjects during the day and night. We attempted to determine whether episcleral venous pressure could explain the difference in the sitting and supine positions. PARTICIPANTS AND METHODS: We compared episcleral venous pressure, intraocular pressure, and blood pressure in a group of younger subjects aged 18 to 30 years and in a group of older subjects aged 65 years or older. The above measurements were performed in the sitting position and after 15 minutes in the supine position. RESULTS: The main difference between the groups was their systemic conditions. Comparing both groups, episcleral venous pressure and intraocular pressure were not different in the sitting position. However, in the supine position, episcleral venous pressure (9.6 vs. 8.3 mm Hg) (P < 0.01) and intraocular pressure (17.1 vs. 15.6 mm Hg) (P < 0.05) were higher in the older group. Statistically, a within-group analysis showed a significant increase in intraocular pressure in the supine position for both the younger (+ 0.8 mm Hg) (P < 0.001) and older subjects (+ 1.8 mm Hg) (P < 0.02). This was associated with an increased episcleral venous pressure in younger (+ 0.4 mm Hg) (P < 0.001) and older subjects (+1 mm Hg) (P < 0.02). There was no gender difference in intraocular pressure and episcleral venous pressure. No differences were found for intraocular pressure and episcleral venous pressure in subjects having certain systemic conditions. Blood pressure was higher for older subjects (P < 0.001). It decreased in the supine position for both groups (P < 0.001). CONCLUSION: Intraocular pressure and episcleral venous pressure were not different in the younger and older group in the sitting position. They were higher in the supine position for older subjects. There was no gender difference.