PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Prone Position”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,351 records · Page 75Linked to original sources
PubMed1990

Relationship between stone motion, targeting, and fragmentation during experimental biliary lithotripsy.

In vitro experiments in an anthropomorphic phantom were performed to clarify the relationship between stone motion, targeting, and fragmentation. Stone motion was minimized by pinning the stone against the dependent wall of a mock gallbladder cavity during shock wave treatment. Fragmentation was most effective (probably due to increased cavitation effects) when the shock wave traversed fluid at the point of its impact with a stone. The results suggest that treatment with the patient in the supine or oblique position may produce a better outcome than treatment in the prone position. Buoyant stones exhibited the greatest motion, which was often to-and-fro in nature. Although restricting the size of the mock gallbladder cavity reduced stone motion, maintaining a 1-cm fluid path was beneficial for achieving optimal pulverization.

Cholelithiasis↗
PubMed2003

Radiation dose to the lens of eye and thyroid gland in paranasal sinus multislice CT.

CT has become an established examination in the evaluation of the paranasal sinuses. Until recently this was achieved by the direct coronal technique on conventional and single slice helical scanners. With the advent of multislice technology, thin slice axial CT with excellent coronal and sagittal reconstructions is now the norm. We describe a study designed to evaluate the radiation dose to the lens of the eye and thyroid gland in the axial and coronal planes on a Siemens Volume Zoom quad slice scanner at 140 kV and effective mAs of 100 using 1 mm collimation. Thermoluminescent dosimeters were placed on the eyelid and thyroid gland of 29 patients scanned axially in the supine position and a further 28 patients scanned coronally in the prone position with gantry tilt. The results show mean doses of 35.1 mGy (lens) and 2.9 mGy (thyroid gland) in the coronal plane compared with 24.5 mGy (lens) and 1.4 mGy (thyroid gland) in the axial plane. Results obtained from a head phantom and from using the ImPACT CT dose calculator were comparable. The kV and mAs were then reduced to 120 and 40, respectively, and the axial study repeated using the head phantom and predicted doses using the ImPACT CT dose calculator. The low dose scanning technique revealed a lens dose of 9.2 mGy and thyroid dose of 0.4 mGy. The eye dose on a multislice scanner is still substantially less than the threshold dose of 0.5-2 Gy for detectable lens opacities. These results indicate that, in addition to the established perceived advantages of multislice axial sinus CT, i.e. patient comfort, no artefact from dental amalgam and reproducible true coronal images, should be included a decreased radiation dose to both the eye lens and thyroid gland compared with direct coronal scanning.

Adult↗
PubMed1995

Surgical aspects of popliteal artery entrapment syndrome: 26 years of experience with 26 legs.

The authors present their experience in diagnosis, therapy and follow up of the Popliteal Artery Entrapment Syndrome (PAES) during the last 26 years. PAES appears most frequently in young athletic male patients. From 1967 to 1993, 20 patients, 17 male (85%) and 3 female (15%), with 26 entrapment legs were treated. Average age at the time of the first symptoms was 33.5 years and at the time of diagnosis 38.5 years. Six patients suffered from PAES on both legs. In 5 of the 24 operated cases a re-operation was necessary. One case required a third operation. To reduce the postoperative complication rate, surgical technique was chosen according to the anatomical situation. If there was only slight disease of the popliteal wall, the current surgical technique consisted in decompressing the artery and replacing it in the orthotopic position through a direct entrance with the patient in the prone position. If there was severe disease of the popliteal wall, an autologous venous bypass from the popliteal artery segment I to segment III should be done with the patient supine. In our opinion, a primary catheter lysis therapy, which can be indicated for stenosed arteries, should not be done for peristenotic aneurysms. Successful therapy of PAES largely depends on early diagnosis that has been confirmed by CT scan.

Adolescent↗
PubMed1995

Infant sleep position: pediatricians' advice to parents.

OBJECTIVE: The American Academy of Pediatrics' (AAP) recommendation for side or supine sleep position in healthy babies has generated much controversy. We surveyed primary care physicians to determine the effect of the AAP statement on physician attitude toward infant sleep position and advice to parents. METHODS: We sent a 23-question survey to 194 physicians in Western New York. The survey addressed their attitude toward the AAP recommendations and its impact on their advice to parents. RESULTS: Of the 149 physicians treating newborns, 121 (82%) completed the questionnaire; 98% were aware of the AAP statement. The most common sources of information were the AAP (86%) and professional literature (77%). Of the respondents, 79% agreed with the AAP statement. Reasons for reservation were lack of data (64%), potential adverse consequences of supine position (52%), and their own experience (47%). Gender, years in practice, and type of reimbursement did not influence attitude toward the AAP recommendation. The AAP statement increased the frequency with which physicians routinely discussed sleep position from 34 to 70% (P < .02). Physicians recommending the prone position decreased from 57 to 7% (P < .001), while those recommending supine sleep position increased from 10 to 42% (P < .001). CONCLUSIONS: Most physicians agreed with the AAP statement and more frequently discussed sleep position following the AAP recommendations. However, they did not routinely recommend supine sleep position. The majority (69%) recommended the side position even though it is unstable. Although the AAP statement has increased discussion of infant sleep position by primary care physicians in WNY, only a minority recommend that infants sleep supine.

Data Collection↗
PubMed1993

The effect of positioning on hemodynamics and gas exchange in the critically ill: a review.

Positioning of critically ill patients affects hemodynamic and cardiopulmonary outcomes. A review of clinical studies indicates that backrest elevations up to 60 degrees do not affect measurement of intracardiac pressures or cardiac output, but PaO2 may diminish in sitting positions following surgical procedures. In lateral positions, measurement of intracardiac pressures and cardiac output is not recommended, since a uniform reference point has not been identified for lateral positions. In patients with unilateral lung disease, PaO2 increases with the unaffected lung in the dependent position. Despite widespread use, the Trendelenburg position has not been shown to provide consistent beneficial effects. Prone positioning may be beneficial in adult respiratory distress syndrome and in weaning of mechanically ventilated patients. When planning positioning maneuvers, critical care nurses should consider these effects in relation to the specific needs of each patient. Hemodynamic and cardiopulmonary responses to positioning should be evaluated in conjunction with other therapeutic modalities such as those designed to preserve skin integrity and improve comfort.

Age Factors↗
PubMed1977

Spinal arterio-venous malformations simulating multiple sclerosis: importance of early diagnosis.

Two cases of spinal arteriovenous malformation (AVM) in young patients are presented. Symptoms were compatible with the spinal form of multiple sclerosis in both cases. The lesions were not diagnosed on initial evaluation. Subsequently they were found by myelography and arteriography, the one eight months and the other nine years after the first symptoms. The contrasting clinical courses of the two patients suggest that: (a) the diagnosis of multiple sclerosis where symptoms and signs are restricted to the spinal cord should be made only after a thorough investigation which includes myelography, to rule out the presence of a surgically correctible lesion such as an AVM; (b) myelography should be carried out in both the supine and prone positions as an AVM may be completely missed by routine prone myelography views; (c) early surgery of the resectable AVM may prevent a progressive deterioration of neurological function, making early diagnosis particularly important.

Adult↗
PubMedDate not supplied

Measures of cardiac repolarization and body position in infants.

Sudden Infant Death Syndrome (SIDS) is the most common cause of death in children between 1 and 6 months of age. Recent data suggest that a prolonged QTc interval on the 12-lead electrocardiogram (ECG) is associated with SIDS. Prone body position during sleep is also known to be a risk factor for SIDS; this has prompted the American Academy of Pediatrics to promote the "Back to Sleep" campaign. We postulated that the QTc interval in infants might change as a function of body position, linking the observations relating body position and QTc interval to SIDS. We recorded ECGs in a group of infants in both the supine and prone position to determine if the QTc interval and QT dispersion differ between the 2 positions. Forty-seven standard 12-lead EGGs and high-amplitude, rapid-sweep 12-lead EGGs were performed on 45 healthy infants (mean age 26 +/- 40 days) in both the supine and prone positions. The infants were asleep in a quiet, restful state. The ECGs were reviewed by 2 investigators blinded to the position of the infants during recording. Measurements included the average QTc interval (using Bazett's correction) and QT dispersion (the difference between the longest and the shortest QT intervals on a standard 12-lead EKG). The study was designed to detect a 3% difference in QTc interval with 80% power and alpha = 0.05. All subjects had telephone or clinical follow-up at 1 year. The average QTc interval was 403 +/- 20 milliseconds (msec) in the supine position and 405 +/- 27 msec in the prone position (p = NS). The QT dispersion was 20 +/- 12 msec in the supine position and 22 +/- 13 msec in the prone position (p = NS). One infant in the study group died of SIDS at the age of 3 months. The EGG of this patient revealed a QTc interval of 382 msec in the supine position and 407 msec in the prone position; the QT dispersion was 34 msec in the supine position and 34 msec in the prone position. We found no difference in QTc interval or QT dispersion as a function of body position in healthy infants resting quietly. Prolongation of the QTc interval is unlikely to explain the increased risk for SIDS associated with prone body position in the general population of healthy infants, unless patients with long QT syndrome are somehow more influenced by body position than normal patients are.

Electrocardiography↗
PubMed1991

The comparative assessment of paraspinal tissue compliance in asymptomatic female and male subjects in both prone and standing positions.

Segmental bilateral paraspinal tissue compliance measures were obtained from 50 male and 50 female asymptomatic subjects (vertebral segments C7-L5). Interexaminer concordance for the taking of the measure was found to be extremely high (r greater than .90). Additionally, test-retest measures obtained from the same subjects initially, and again 15 min or 2 wk later indicated fairly low short-term as well as long-term temporal variabilities for the measure. The greatest levels of variability were encountered at lumbar segments, particularly with 2 wk intervals between assessments, and when measures were obtained with subjects in the standing, rather than prone, position. Data generated by this study suggest that tissue compliance assessments may provide useful information with respect to the contractile state of the paraspinal musculature at various regions or segmental levels.

Adult↗
PubMed2004

Prone versus supine patient positioning during gated 99mTc-sestamibi SPECT: effect on left ventricular volumes, ejection fraction, and heart rate.

UNLABELLED: Gated myocardial perfusion SPECT allows assessment of left ventricular end-diastolic volume (EDV), left ventricular end-systolic volume (ESV), left ventricular stroke volume (SV), and left ventricular ejection fraction (LVEF). Acquiring images with the patient both prone and supine is an approved method of identifying and reducing artifacts. Yet prone positioning alters physiologic conditions. This study investigated how prone versus supine patient positioning during gated SPECT affects EDV, ESV, SV, LVEF, and heart rate. METHODS: Forty-eight patients scheduled for routine myocardial perfusion imaging were examined with gated (99m)Tc-sestamibi SPECT (at rest) while positioned prone and supine (consecutively, in random order). All parameters for both acquisitions were calculated using the commercially available QGS algorithm. RESULTS: Whereas EDV and SV were significantly lower (P < 0.0004) for prone acquisitions (EDV, 110.5 +/- 39.1 mL; SV, 55.9 +/- 13.3 mL) than for supine acquisitions (EDV, 116.9 +/- 36.2 mL; SV, 61.0 +/- 14.5 mL), ESV and LVEF did not differ significantly. Heart rate was significantly higher (P < 0.0001) during prone acquisitions (69.1 +/- 10.5 min(-1)) than during supine acquisitions (66.5 +/- 10.0 min(-1)). CONCLUSION: The observed position-dependent effect on EDV, SV, and heart rate might be explained by decreased arterial filling and increased sympathetic nerve activity. Hence, supine reference data should not be used to classify the results of prone acquisitions.

Adult↗
PubMed1980

Prone-supine change in organ position: CT demonstration.

A study of positional variation of anatomic structures in 38 patients undergoing CT in both the supine and prone positions prior to beginning radiotherapy is reported. Within the thorax, turning the patient to the prone position resulted in a ventral shift of hilar structures in 36 of 38 patients. In two patients, pulmonary metastases shifted ventrally and caudally in the prone position. In all cases reviewed, prone positioning produced a ventral shift of the heart and great vessels. Within the abdomen, prone positioning produced ventral as well as caudal shift of both the liver and spleen in 34 of 38 patients. In all of the patients, a ventral shift of the kidneys as well as caudal shift was noted. Little or no variation of position was noted in cervical or pelvic structures with changing body positions.

Digestive System↗
PubMed1989

Alprazolam reduces stress-induced mortality in cardiomyopathic hamsters.

These experiments examined the role of several variables involved in the production of serious, stress-induced disease. Experiments 1 and 2 indicated that stress may not be medically dangerous except in animals with a predisposition or vulnerability to disease. Repeated exposure to cold-immobilization produced no detectable ill effects in healthy hamsters, but it was lethal for cardiomyopathic hamsters (CMHs). Experiment 3 showed that stressor intensity was also critical to the outcome of stress. CMHs succumbed when they were stressed in the supine position, but not when they were immobilized in the less stressful prone position. In Experiment 4, we attempted to reduce the stressfulness of cold-immobilization with the anxiolytic alprazolam. Alprazolam effectively blocked stress-induced mortality. In addition, we found that poststress body temperature was a crude predictor of an animal's ability to cope with stress. Alprazolam prevented CMHs from developing stress-induced hypothermia.

Alprazolam↗
PubMed1992

Positional asphyxia during law enforcement transport.

Three cases of positional asphyxia are described that occurred while victims were in a prone position in rear compartments of police patrol cars. These deaths are attributed to positional asphyxia. Autopsy findings and specific scene and circumstantial correlations of the investigation are discussed with emphasis placed on the limitations of interpretation of the anatomic changes at autopsy.

Adult↗
PubMed1990

Mechanical role of expiratory muscles during breathing in prone anesthetized dogs.

The purpose of the present study was to assess the mechanical role of the expiratory muscles during spontaneous breathing in prone animals. The electromyographic (EMG) activity of the triangularis sterni, the rectus abdominis, the external oblique, and the transversus abdominis was studied in 10 dogs light anesthetized with pentobarbital sodium. EMGs were recorded during spontaneous steady-state breathing in supine and prone suspended animals both before and after cervical vagotomy. We also measured the end-expiratory lung volume [functional residual capacity (FRC)] in supine and prone positions to assess the mechanical role of expiratory muscle activation in prone dogs. Spontaneous breathing in the prone posture elicited a significant recruitment of the triangularis sterni, the external oblique, and the transversus abdominis (P less than 0.05). Bilateral cervical vagotomy eliminated the postural activation of the external oblique and the transversus abdominis but not the triangularis sterni. Changes in posture during control and after cervical vagotomy were associated with an increase in FRC. However, changes in FRC, on average, were 132.3 +/- 33.8 (SE) ml larger (P less than 0.01) postvagotomy. We conclude that spontaneous breathing in prone anesthetized dogs is associated with a marked phasic expiratory recruitment of rib cage and abdominal muscles. The present data also indicate that by relaxing at end expiration the expiratory muscles of the abdominal region are directly responsible for generating roughly 40% of the tidal volume.

Anesthesia, General↗
PubMed2004

Lower pulmonary diffusing capacity in the prone vs. supine posture.

We evaluated the effect of prone positioning on gas-transfer characteristics in normal human subjects. Single-breath (SB) and rebreathing (RB) maneuvers were employed to assess carbon monoxide diffusing capacity (DlCO), its components related to capillary blood volume (Vc) and membrane diffusing capacity (Dm), pulmonary tissue volume (Vti), and cardiac output (Qc). Alveolar volume (Va) was significantly greater prone than supine, irrespective of the test maneuver used. Nevertheless, Dl(CO) was consistently lower prone than supine, a difference that was enhanced when appropriately corrected for the higher Va prone. When adequately corrected for Va, diffusing capacity significantly decreased by 8% from supine to prone [SB: Dl(CO,corr) supine vs. prone: 32.6 +/- 2.3 (SE) vs. 30.0 +/- 2 ml x min(-1) x mmHg(-1) stpd; RB: Dl(CO,corr) supine vs. prone: 30.2 +/- 2.2 (SE) vs. 27.8 +/- 2.0 ml x min(-1) x mmHg(-1) stpd]. Both Vc and Dm showed a tendency to decrease from supine to prone, but neither reached significance. Finally, there were no significant differences in Vti or Qc between supine and prone. We interpret the lower diffusing capacity of the healthy lung in the prone posture based on the relatively larger space occupied by the heart in the dependent lung zones, leaving less space for zone 3 capillaries, and on the relatively lower position of the heart, leaving the zone 3 capillaries less engorged.

Adult↗
PubMed2002

Effects of prone and supine positions on sleep state and stress responses in mechanically ventilated preterm infants during the first postnatal week.

BACKGROUND/RATIONALE: Preterm infants in mechanical ventilation are vulnerable and may manifest physiological instability and a disorganized behavioural state when responding to external stimuli. Adequate positioning strategies may play an important role in protecting infants from environmental stressor and assisting quality of sleep. However, no study has examined effects of prone and supine positions on behavioural state and stress signs including startle, tremor, and twitch responses for ventilated preterm infants during the critical first week postbirth. AIM OF THE STUDY: The purpose of this study was to compare effects of prone and supine positions on behavioural state and stress responses in mechanically ventilated preterm infants. DESIGN/METHODS: The infants were aged 25-36 weeks of gestation, < or = 7 days of age, and without sedation or congenital abnormalities. Using a crossover design, 28 infants were randomly assigned to supine/prone or prone/supine position sequence. Infants were placed in each position for 2 hours. A stabilization period of 10 minutes before observation of each position was allowed. During the protocol, care procedures were kept minimal and ventilator settings remained unchanged. Behavioural state and frequencies of stress signs including startle, tremor, and twitch were systemically recorded and analysed with repeated measures analysis of variance. FINDINGS: Infants when prone compared with supine had (a) less crying, less active sleep, and more quiet sleep states, and (b) fewer stress responses of startle, tremor, and twitch. CONCLUSION: Results indicate that prone positioning improves the quality of sleep and decreases stress for ventilated preterm infants during the first week postbirth. These may conserve energy and assist infants' extrauterine adaptation.

Cross-Over Studies↗
PubMed1998

Trends and predictors of infant sleep positions in Georgia, 1990 to 1995.

BACKGROUND: In recent years, the prone sleeping position has emerged as the strongest modifiable risk factor for sudden infant death syndrome, the leading cause of infant mortality between 1 month and 1 year of age in the United States. Since April 1992, sudden infant death syndrome risk-reduction strategies have included the promotion of the back or side sleeping position (nonprone) for healthy infants younger than 1 year of age. Most recently, the back position has been advocated as the best sleeping position and the side position as an alternative. METHODS: To evaluate trends in prevalence of the prone position from 1990 to 1995, we used data available from the Georgia Women's Health Survey, a random digit-dialed telephone survey of 3130 women 15 to 44 years of age. We examined the position in which women put their infant to sleep in the first 2 months of life for their most recent live birth (N = 868) and determined independent predictors of prone sleep position among women who consistently used the prone or the back/side position (n = 636) using multiple logistic regression. RESULTS: The prevalence of mothers who put their infant to sleep in the prone position significantly decreased, from 49% in 1990 to 15% in 1995. This decrease is primarily attributable to a major shift to the side position rather than to the back. Using multiple logistic regression, we found the prone sleeping position to be significantly higher among women who entered prenatal care after the first trimester (odds ratio [OR], 3.6; 95% confidence interval [CI], 1.4-9.2), were black (OR, 2.1; 95% CI, 1.4-3.1), had less than a high school education (OR, 2.2; 95% CI, 1.4-3.4), and were living in rural Georgia (OR, 1.9; 95% CI, 1.3-2.7). For the period after April 1992, women who had previous children were 2.6 (OR, 95% CI, 1.7-4.1) times more likely to use the prone sleep position than were first-time mothers. CONCLUSIONS: The prevalence of the use of the prone sleep position for infants decreased significantly over the study period. This decrease coincided with national efforts to promote the back or side sleeping position. Increased efforts should target groups who are more likely to use the prone position to attain the national goal of </=10% of prone position prevalence by the year 2000, with emphasis on placing the infant on the back.

Adolescent↗