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PubMed1990

Minimization of small bowel volume within treatment fields utilizing customized "belly boards".

Thirty consecutive patients with pelvic malignancies were evaluated prospectively for the impact of a novel bowel minimization device ("belly board") on the volume of small bowel included within a four field pelvic radiation plan. A customized polyurethane and styrofoam bowel immobilization mold was created for each patient in the prone position. Using contrast enhanced CT scanning on a dedicated radiation treatment planning scanner, we imaged the location of the small intestine in the supine position and the prone position aided by the "belly board". Custom in-house interactive image analysis software was developed to allow volumetric determination of small bowel within the treatment portals. The mean small bowel volume was reduced by 66% (299 cm3 to 102 cm3), comparing the standard supine position to the prone position assisted by the "belly board". In 13 patients without prior pelvic surgery, the small bowel volume reduction was a more dramatic 74% (334 cm3 to 88 cm3). All patients were found to benefit from this prone "belly board" setup regardless of body habitus, weight, and age. Compliance with the set-up including use of bladder distension was excellent. All patients completed their pelvic radiotherapy without requiring a treatment break. Weight loss at completion averaged less than 5%. Seventy-six percent of patients experienced little or no diarrhea. This technique is comfortable, inexpensive, highly reproducible, and permits maximal bowel displacement from standard pelvic radiotherapy fields.

Adult↗
PubMedDate not supplied

Prevalence and predictors of the prone sleep position among inner-city infants.

CONTEXT: The prone sleep position is associated with an increased risk of sudden infant death syndrome (SIDS), but few studies have assessed factors associated with the choice of infant sleep position. OBJECTIVES: To describe infant sleep position in a cohort of infants born to predominantly low-income, inner-city mothers and to identify predictors of the prone sleep position in this population. DESIGN: Prospective birth cohort study. PATIENTS AND SETTING: Three hundred ninety-four mother-infant dyads, systematically selected from 3 District of Columbia hospitals between August 1995 and September 1996. Mothers were interviewed shortly after delivery and again at 3 to 7 months postpartum. MAIN OUTCOME MEASURES: Position in which infants were placed for sleep on the night prior to the 3- to 7-month interview. RESULTS: At 3 to 7 months of age, 157 infants (40%) were placed for sleep in the prone position. Independent predictors of prone sleep position included poverty (odds ratio [OR], 1.81; 95% confidence interval [CI], 1.10-2.99), black race (OR, 2.06; 95% CI, 1.05-4.04), presence of infant's grandmother in the home (OR, 1.83; 95% CI, 1.11-3.00), and intent, as measured shortly after delivery, to place the infant in the prone position (OR, 2.28; 95% CI, 1.44-3.60). Importantly, of the 43 mothers who observed their infants in the prone sleep position while in the hospital, 40 (93%) intended to place their infants prone at home. CONCLUSIONS: A substantial proportion of infants in this predominantly low-income population were placed in the prone sleep position. Educational efforts should address both initial intentions and reinforcement of the correct sleep position, once initiated. Hospitals should ensure that healthy newborn infants are placed in the supine sleep position during the postpartum hospital stay.

Humans↗
PubMed2002

Bowel wall visualisation at CT colonography.

PURPOSE: To evaluate the quality of bowel wall visualisation at CT colonography and the impact of examination in the supine and prone positions. MATERIAL AND METHODS: After bowel preparation, 111 patients underwent CT colonography. Air distension, degree of fluid redistribution with change in body position (supine and prone), influence of residual stool on bowel wall assessability, and quality of overall colon visualisation were evaluated using scales. RESULTS: Thirty of 110 patients (27%) had complete overall visualisation of the colon wall and 52 (47%) had subtotal visualisation of a limited part of the colon. The entire colon was more often air-filled in the prone position (46%) than in the supine position (18%). Joint review of supine and prone data showed that for all colon segments, except the sigmoid (86%), > or =95% of the patients had complete air filling. All patients had residual fluid. In 75% to 99%, depending on segment, fluid did not interfere with the bowel wall visualisation in the combined evaluation of supine and prone data sets. Thirty-one patients had residual stool with potential negative influence on polyp detection. CONCLUSIONS: The colon wall was completely, or almost completely, visualised in 75% of the patients, and examination in the supine and prone positions was necessary for complete visualisation.

Adult↗
PubMed1994

Recommendations to avoid the prone sleeping position and recent statistics for sudden infant death syndrome in the United States.

OBJECTIVE: To determine whether two recent, nonsynchronized recommendations to avoid the prone position for sleeping infants were each followed by a decline in the incidence or expected number of cases of sudden infant death syndrome (SIDS). DATA SOURCES: Data were collected from SIDS counseling programs, state vital statistics, and medical examiner records of 44 states and the city of Los Angeles, Calif. Data for a state were excluded because of either incompleteness or nonresponsiveness to request. DATA SYNTHESIS: In the 8 months following an article in the Seattle Times advising against the use of the prone position for sleeping infants, the incidence of SIDS fell by 52.0% in King County (where 32 households in every 100 receive the Seattle Times) and by 19.9% in Snohomish County (16 in 100 households). In the remaining 37 counties of Washington State (on average, < 1 in 100 households are subscribers), the incidence rose 3.4%. Examination of medical examiner records for King County and Snohomish County revealed no compensatory increase in other causes of death and no cases attributed to aspiration. In the 12 months following the initial 8 months, the number of SIDS cases in King County remained at approximately half the previous annual average (25 vs 49 cases). At the national level, the American Academy of Pediatrics' recommendation on April 15, 1992, was followed in the next 6 months by a decrease of 12.0% in the number of SIDS cases compared with the previous year. CONCLUSIONS: The results are consistent with those of intervention programs in other countries. A national campaign to inform parents of the risk of the prone position in early infancy should be given serious consideration.

Cause of Death↗
PubMed1999

Prone and left lateral positioning reduce gastro-oesophageal reflux in preterm infants.

AIM: To examine the effect of body position on clinically significant gastro-oesophageal reflux (GOR) in preterm infants. METHODS: Eighteen preterm infants with clinically significant GOR were studied prospectively using 24 hour lower oesophageal pH monitoring. Infants were nursed in three positions (prone, left, and right lateral) for 8 hours in each position, with the order randomly assigned. Data were analysed using analysis of covariance. RESULTS: The median (range) reflux index (RI) for the group was 13.8% (5.8-40. 4). There was no significant difference in the mean time spent in each position. RI (mean % (SEM)) was significantly less in prone (6. 3 (1.7)) and left lateral positions (11.0 (2.2)), when compared with the right lateral position (29.4 (3.2)); p<0.001. The mean (SEM) longest episodes (mins) of GOR were reduced by prone and left positions (8.6 (2.2) and 10.0 (2.4), respectively) compared with the right position (26.0 (3.9)); p<0.001. The mean (SE) number of episodes was reduced by prone (15.4 (2.8)) and left (24.6 (3.5)) positions when compared with right (41.6 (4.6)) (p<0.001). CONCLUSIONS: Prone and left lateral positions significantly reduce the severity of GOR, by reducing the number of episodes and the duration of the longest episodes. Such positioning offers a useful adjunct to the treatment in hospital of preterm infants with gastro-oesophageal reflux.

Analysis of Variance↗
PubMed1999

Postural differences in cardiac dynamics during quiet and active sleep in low birthweight infants.

To study the effects of body position (supine versus prone) on changes in cardiac inter-beat interval during quiet and active sleep, 6-h continuous electrocardiographic recordings and simultaneous minute-by-minute behavioural activity state assignments were made in 61 healthy, growing, low birthweight infants. The infants weighed 795-1600 g at birth and ranged between 30-38 wk in postconceptual age. Infants were randomly assigned to the supine or prone position for the first 3 h of each study; the position was reversed for the second 3 h. Higher heart rates and lower time and frequency domain measures of inter-beat interval variability were observed in the prone position as compared to the supine position, during both quiet and active sleep. In addition, an analysis of consecutive increases and decreases in the instantaneous heart rate revealed a lower incidence of sustained accelerations or decelerations in the prone position. Although consistent findings concerning inter-beat interval variability and sleeping position were obtained from all analytic techniques, the differences derived from analysis of consecutive inter-beat changes were the most robust. These differences in multiple measures of cardiac rate and rhythm between prone and supine positions suggest that autonomic control of the heart is altered by body position, the net effect on heart rate being increased sympathetic dominance.

Autonomic Nervous System↗
PubMed2001

[Anterior chamber structural change in postural variation in pseudoexfoliation syndrome].

PURPOSE: The anterior chamber structure in the supine position and the prone position was investigated with ultrasound biomicroscopy (UBM) in pseudoexfoliation syndrome (PE). METHODS: We studied 12 eyes of 12 PE subjects. Patients were placed in the supine position for 30 minutes, after which UBM was performed. The UBM was repeated after 30 minutes in the prone position. Anterior chamber depth (ACD), angle opening distance 500 microns (AOD 500), and angle recess area (ARA) in 4 quadrants were measured. RESULTS: Following the postural change from the supine position to the prone position, ACD decreased significantly (p < 0.0001). AOD 500 and ARA decreased significantly in the superior (AOD 500: p < 0.05, ARA: p = 0.03) and temporal quadrants (AOD 500: p < 0.0001, ARA: p < 0.0001). CONCLUSIONS: The anterior chamber structural change was greater in the temporal and superior quadrants in the PE eyes. This corresponds with previous reports that zonular involvement by pseudoexfoliation material is more pronounced temporally and superiorly.

Anterior Chamber↗
PubMed1990

Effects on behavior state of prone versus seated positioning for infants with gastroesophageal reflux.

To evaluate the effect of positioning on behavior in infants with gastroesophageal reflux, 48 infants younger than 6 months of age (range 1.5 to 28 weeks, median 13.5) with reflux were positioned continuously prone (24 infants) or seated (24 infants) during a 120-minute postprandial period, during which behavior was monitored continuously. The prone position was associated with more sleep time, 83.5 (16 to 113) vs 43 (0 to 117) minutes, P = .01. This increase in sleep time in the prone position could be largely accounted for by a tendency toward a decrease in crying time, 19 (0 to 82) vs 38.5 (0 to 91) minutes, P = .07, which is expressed further by the significantly smaller number of prone than seated infants who cried longer than 30 minutes, P = .02. A parallel reduction in noncrying awake time in the prone vs the seated position was not significant: 15 (0-51) vs 31 (3 to 84) minutes, P = .13.

Behavior↗
PubMed2002

Pediatric ARDS: effect of supine-prone postural changes on oxygenation.

OBJECTIVE: To determine the effect of repeated prone positioning (supine-prone/prone-supine) on oxygenation in children suffering from ARDS. DESIGN: Single-center prospective case series. SETTING: University pediatric ICU. PATIENTS: Consecutive pediatric patients with severe ARDS (PaO(2)/FiO(2) <200, Murray score >2.5). INTERVENTIONS: Patients were treated as soon as possible with supine-prone/prone-supine positioning every 8 h until clinical improvement or death occurred. MEASUREMENTS AND RESULTS: Twenty-three patients who had ARDS (0.5-months to 12.6-years-old), were placed in the prone position within 56+/-109 h after the diagnosis of ARDS. Prone-supine/supine-prone postural changes were repeated every 8 h for 9.7+/-5.5 days. Changes in PaO(2)/FiO(2) ratio during supine-prone and prone-supine positioning were evaluated. A positive change was defined as an increase of 15% of baseline value. The patient was classified as a responder when the mean increase in the prone position was greater than 15%. There were 18 responders and five non-responders. The responders showed an increase in PaO(2)/FiO(2) ratio of 22%, from 91+/-33 to 112+/-43 (P <0.001), when they were placed from the supine to the prone position. Their PaO(2)/FiO(2) ratio dropped from 109+/- 37 to 94 +/-36, P = 0.011, when changed from the prone to supine position. The overall mortality rate in this series was 48% (11 patients), which was higher in the non-responders (80%) than in the responders (39%), although this difference was not statistically significant (P = 0.95). CONCLUSIONS: The prone position improves oxygenation in a significant proportion of children with ARDS. Although no statistically significant difference was found for the mortality rate, it was higher for the non-responders (80%) vs the responders (39%).

Acute Disease↗
PubMed1998

[Spinal microsurgery at the thoracic to sacral level in the "prone-oblique" position].

Until the present time, almost all posterior approaches to the thoracic to sacral region have been made in either the knee-elbow or the prone position. Those positions, however, have potential disadvantages such as respiratory suppression and/or disturbance of venous return due to compression of the anterior chest and belly. In order to avoid the above mentioned disadvantages, the patient was laid on the operating table in a "Prone-Oblique" position, with the body rotating about 40 degrees around the long axis. The authors performed, with successful results, spinal operations via the posterior route in the "Prone-Oblique" position in 30 cases. An illustrative case was presented of a metastatic intramedullary tumor at the T11/12 level from an unresectable mammary cancer. The cancer had infiltrated and bulged out of the left anterior chest wall so severely and extensively that an operation in the conventional position was impossible. The metastatic tumor was totally and successfully removed via the posterior approach in the "Prone-Oblique" position without any complications related to the position. This "Prone-Oblique" position seems to be physiologically suitable, giving rise to no harmful compression of any part of the patient's body and it provides the surgeon a comfortable posture and a good operative view during microsurgery.

Adult↗
PubMedDate not supplied

Achieving dose reduction in lumbar spine radiography.

Conventional lumbar spine examinations are performed by placing the patient in the supine position. The alternative prone position is less commonly used. In this study, researchers measured entrance skin exposure for both supine and prone positioning techniques and the radiation dose to the eyes, thyroid, ovaries, testes and bone marrow. Compared with the AP projection, the PA projection produced a moderately higher bone marrow dose (28%), but resulted in a slightly reduced dose (17%) to the thyroid and greatly reduced doses (200+%) to the eyes, ovaries, uterus and testes. The PA projection also produced an ESE 52% lower than the AP projection. Results suggest an advantage to using prone positioning for lumbar spine examinations.

Adult↗
PubMed1991

Prone sleeping position and SIDS: evidence from recent case-control and cohort studies in Tasmania.

The most recent data from the cohort and case-control studies of SIDS and prone position recently reported from Tasmania are reviewed. The cohort analysis was based on 4103 infants born between 1 January 1988 and 1 December 1990 assessed as being at high risk at birth, of whom 29 later died of SIDS. A matched analysis which controlled for infant birthweight and maternal age indicated that prone sleeping position was associated with an increased risk of SIDS (OR 3.92, 95% Cl [1.37-11.24]). The case-control study was based on all (n = 55) Tasmanian SIDS death from October 1989 to April 1991 and matched live controls. The unadjusted odds ratio for prone position and SIDS was 5.04 (95% Cl [2.29-11.11]). The population attributable risk percentage, based on the high risk cohort data, was 0.38 (95% Cl [0.35-0.41]), suggesting that a significant reduction in SIDS incidence might occur if the prevalence of the prone sleeping position in the infant population were reduced. Other factors which may be important for the development of any public health interventions to reduce SIDS based on these findings are discussed.

Case-Control Studies↗
PubMed2006

The use of somatosensory evoked potentials to determine the relationship between patient positioning and impending upper extremity nerve injury during spine surgery: a retrospective analysis.

Somatosensory evoked potential (SSEP) monitoring is used to prevent nerve damage in spine surgery and to detect changes in upper extremity nerve function. Upper extremity SSEP conduction changes may indicate impending nerve injury. We investigated the effect of operative positioning on upper extremity nerve function retrospectively in 1000 consecutive spine surgeries that used SSEP monitoring. The vast majority (92%) of upper extremity SSEP changes were reversed by modifying the arm position and were therefore classified as position-related. The incidence of position-related upper extremity SSEP changes was calculated and compared for five different surgical positions: supine arms out, supine arms tucked, lateral decubitus position, prone arms tucked, and the prone "superman" position. The overall incidence of position-related upper extremity SSEP changes was 6.1%. The lateral decubitus position (7.5%) and prone superman position (7.0%) had a significantly more frequent incidence of position-related upper extremity SSEP changes (P < 0.0001, Z-test for Poisson counts) compared with other positions (1.8%-3.2%). No patient with a reversible SSEP change developed a new postoperative deficit in the affected extremity. SSEP monitoring is of value in identifying and reversing impending upper extremity peripheral nerve injury.

Adolescent↗
PubMed2004

[The changes in effective local blood perfusion and compensatory ventilation in different lung areas of acute respiratory distress syndrome rabbits model].

OBJECTIVE: To discuss the mechanism of severe hypoxemia that induced with acute respiratory distress syndrome (ARDS) by way of observing the effective local blood perfusion in different lung areas of ARDS rabbits. METHODS: ARDS rabbit models were established by injecting oleic acid through central vein, and the results of effective local blood perfusion in different areas of rabbit lung (upper area, abdominal area, and dorsal area of right lung)with PIM-II laser perfusion imager and arterial blood gas under different ventilation modes [large tidal volume ventilation, low tidal volume ventilation + positive end-expiratory pressure (PEEP), prone position + large tidal volume ventilation, and prone position + low tidal volume ventilation + PEEP] were measured. RESULTS: The results of oxygenation index were significantly getting worsen after lung injury, and after receiving lung protective ventilation (including low tidal volume + PEEP, prone position + low tidal volume + PEEP), the indexes were taking a turn to the better. After lung injury, the results of effective local lung blood perfusion index (including upper area, abdominal area, and dorsal area) under right lung of ARDS rabbits decreased in the experimental ARDS groups. The results of experimental dorsal area group decreased most significantly, and the results of experimental upper area group changed most lightly. We observed that the effects of receiving low tidal volume + PEEP ventilation were not as good as prone position + low tidal volume + PEEP ventilation in the dorsal area of the rabbit lung compared to the results of effective local area lung blood perfusion index between two ventilation modes, there showed significantly differences in statistics. CONCLUSION: We indicated that the one of the main mechanisms of severe hypoxemia in ARDS might be caught by the shunt between pulmonary artery and pulmonary vein just like physiological right to left shunt, which caused severe ventilation/perfusion disturbance. Both low tidal volume ventilation + PEEP and prone position + low tidal volume ventilation + PEEP had good effects on ameliorating local blood perfusion, and the effects of ventilation mode of prone position + low tidal volume ventilation +PEEP might be better.

Animals↗
PubMed1996

Risk factors for the infant prone sleep position.

OBJECTIVE: To identify parental characteristics associated with infants being placed to sleep in the prone position. STUDY DESIGN: Cross-sectional survey. PATIENTS: Randomly selected King County, Washington, infants born on the same days as King County infants who died of sudden infant death syndrome between November 1992 and October 1994. METHODS: Parents of study infants responded to a telephone interview about sleep position in their infants. Parents were asked how they usually put their infants to bed during the previous 2 weeks, and if they were aware of any recent advice on sleep position in young infants. Demographic data were also collected during the telephone interview. Logistic regression was used to identify infant and parental characteristics associated with the prone sleep position. RESULTS: Parents of 178 infants were interviewed; 28.1% responded that their infants usually slept prone, 66.9% slept nonprone, and 5% had no usual sleep position. Parents who were unaware of sleep position advice were more likely to place their infants prone than those who were aware of this advice (odds ratio, 3.5; 95% confidence interval, 1.5-7.8). Among parents who were aware of sleep position advice, mothers younger than 20 years were more than 10 times as likely to place their infants prone than were older mothers (odds ratio, 10.7; 95% confidence interval, 1.1-107.0). For those who were unaware of sleep position advice, single mothers were more likely to place their infants prone (odds ratio, 14.0; 95% confidence interval, 1.5-133.2). Single mothers and parents of low-birth-weight infants were more likely to be unaware of recent medical advice regarding optimal sleep position for infants. CONCLUSIONS: The results of this study may provide direction to future efforts to encourage nonprone sleeping. Knowledge of the risk is associated with decreased use of prone sleep position. Single mothers should be targeted for intensive educational efforts regarding the hazards of prone sleeping. Among teenage mothers, awareness of the association between prone sleeping and sudden infant death syndrome may not be adequate to change behavior; educational interventions that are more focused for this age group may be needed.

Adult↗
PubMed1992

[Three dimensional analysis of caloric nystagmus using computerized image recognition].

Three-component analysis of caloric nystagmus, focusing on horizontal, vertical, and torsional directions, using a newly developed computerized eye movement analysis system was carried out in ten normal human subjects. The caloric response was induced by cold stimulation to the right ear while the subjects were in supine and prone positions. The directions of the three components of nystagmus, were left in ten subjects (10), upward (8) or downward (2), and clockwise (10) in the supine position. In the prone position, on the other hand, the three components were directed toward the right (10), downward (5), upward (3), and counterclockwise (10) or were not present (2). These findings indicate that caloric stimulation activates the three semicircular canals simultaneously. In addition the changes in the direction of nystagmus in the supine and prone positions could not be explained in detail by the convection theory of caloric response alone.

Adult↗
PubMed2006

Lung and 'end organ' injury due to mechanical ventilation in animals: comparison between the prone and supine positions.

INTRODUCTION: Use of the prone position in patients with acute lung injury improves their oxygenation. Most of these patients die from multisystem organ failure and not from hypoxia, however. Moreover, there is some evidence that the organ failure is caused by increased cell apoptosis. In the present study we therefore examined whether the position of the patients affects histological changes and apoptosis in the lung and 'end organs', including the brain, heart, diaphragm, liver, kidneys and small intestine. METHODS: Ten mechanically ventilated sheep with a tidal volume of 15 ml/kg body weight were studied for 90 minutes. Five sheep were placed in the supine position and five sheep were placed in the prone position during the experiment. Lung changes were analyzed histologically using a semiquantitative scoring system and the extent of apoptosis was investigated with the TUNEL method. RESULTS: In the supine position intra-alveolar hemorrhage appeared predominantly in the dorsal areas, while the other histopathologic lesions were homogeneously distributed throughout the lungs. In the prone position, all histological changes were homogeneously distributed. A significantly higher score of lung injury was found in the supine position than in the prone position (4.63 +/- 0.58 and 2.17 +/- 0.19, respectively) (P < 0.0001). The histopathologic changes were accompanied by increased apoptosis (TUNEL method). In the supine position, the apoptotic index in the lung and in most of the 'end organs' was significantly higher compared with the prone position (all P < 0.005). Interestingly, the apoptotic index was higher in dorsal areas compared with ventral areas in both the prone and supine positions (P < 0.003 and P < 0.02, respectively). CONCLUSION: Our results suggest that the prone position appears to reduce the severity and the extent of lung injury, and is associated with decreased apoptosis in the lung and 'end organs'.

Animals↗