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PubMed1999

Effects of body position on blood gases and lung mechanics of infants with chronic lung disease during tube feeding.

BACKGROUND: The effects of body position and feeding on lung mechanics and blood gases in very low birthweight infants with chronic lung disease (CLD) is not fully elucidated. METHODS: Seven very low birthweight infants who were being mechanically ventilated because of CLD were examined. They were enrolled in this study when their feeding volume exceeded 100 mL/kg per day. Each patient was kept on the same position (either prone or supine) during feeding. Feeding was given by a nasogastric tube for over 1 h every 3 h. Blood gases and lung mechanics were evaluated before, 20 min and 40 min after the initiation of the feeding and at the end of the feeding. RESULTS: The prone position resulted in a significant increase in arterial oxygen saturation during feeding. The tidal volume in the prone position was significantly larger than in the supine position only before feeding. There were no significant differences in minute ventilation between these positions during the study. Pulmonary resistance was not different in either position, but the static compliance and the work of breathing of spontaneous breaths were improved significantly when the infants were in the prone position. In the supine position, work of breathing increased and static compliance decreased significantly with time, while in the prone position, those values did not change significantly. CONCLUSION: The improvement in lung mechanics may partly explain better oxygenation obtained in the prone position. The prone position could decrease energy expenditure for spontaneous breathing and may shorten the period of ventilatory support for very low birthweight infants with CLD.

Analysis of Variance↗

PubMed1980

Nasopharyngeal teratoma.--Report of a case.

A case of nasopharyngeal teratoma with the appearance of a hairy polyp in one month old infant is presented. The patient had a previous history of recurrent attacks of cough, dyspnea and cyanosis on being fed or in a certain body position (prone). The prone position shifted the tip of the tumor with its long stalk over the entrance of the larynx followed by upper airway obstruction. Prompt surgical extirpation prevented the risk of succeeding fatal respiratory event. This uncommon congenital teratoma arising from the nasopharynx should be taken into consideration in differential diagnosis of neonatal or infantile upper respiratory distress.

Epithelium↗

PubMed1996

[Objective determination of refractive changes in silicon oil filled eyes--effect of head position on refraction].

BACKGROUND: The refraction of the eye is altered significantly after silicone oil instillation into the vitreous cavity due to its high refractive index. The degree of the refractive change varies during the daily course and depends on the position of the head. PATIENTS AND METHODS: To analyze the degree and time course of the refractive change depending on the head position we performed refractive measurements in 5 aphakic and 5 phakic silicone oil-filled eyes with attached macula by an automatic handrefractometer. This new device was used for 25 measurements at short intervals in each patient at different eye positions (supine position, prone position and primary eye position). RESULTS: Mean visual acuity in all patients valued 0.14 (+/- 0.05). The highest shift in refraction of +5.95 (+/- 2.63) dpt in spherical equivalents occurred in the aphakic eyes and of +2.45 (+/- 0.71) dpt in the phakic eyes after position change from face up to face down. Three minutes after position change the refraction remained stable in nearly all eyes. Only slight changes in cylinder and corresponding axis were found during the measurements with a mean axial shift of 10.1 (+/- 5.1) degrees. CONCLUSION: Immediately after change of the head position especially aphakic eyes demonstrated remarkable refractive shifts. The results of this study explain patients' complaint of visual changes during the daily course after intraocular silicone oil injection. Refractive alterations evoked by silicone oil stabilized a few minutes after change of the head position.

Adult↗

PubMed1992

Pulmonary effects of body position, PEEP, and surfactant depletion in dogs.

The influence of position (sphinx, lateral, supine), surfactant depletion, and different positive end-expiratory pressure (PEEP) on functional residual capacity (FRC), series dead space (VdS) and compliance of the respiratory system (Crs) were evaluated in five dogs. Ventilation homogeneity as measured by an index (multiple breath alveolar mixing efficiency), oxygenation, and cardiovascular hemodynamics were additionally examined. The dogs were anesthetized with halothane, paralyzed, and mechanically ventilated. FRC and VdS were found to be notably large in dogs, 45 +/- 8 ml/kg and 6 +/- 1 ml/kg, respectively. FRC and ventilation homogeneity were improved in the sphinx position (prone position with upright head). Surfactant depletion by lung lavage with 37 degrees C saline caused an immediate and stable decrease in FRC, Crs, and oxygenation (P less than 0.05, respectively) for about 5 h without marked effects on the circulatory system. FRC and VdS increased with increasing PEEP. At the highest PEEP, 10 cmH2O (1 kPa), Crs decreased (P less than 0.05) and ventilation became more uneven, indicating alveolar overdistension.

Animals↗

PubMed2005

Dynamic soft tissue mobilisation increases hamstring flexibility in healthy male subjects.

OBJECTIVES: The purpose of this study was to investigate the effect of dynamic soft tissue mobilisation (STM) on hamstring flexibility in healthy male subjects. METHODS: Forty five males volunteered to participate in a randomised, controlled single blind design study. Volunteers were randomised to either control, classic STM, or dynamic STM intervention. The control group was positioned prone for 5 min. The classic STM group received standard STM techniques performed in a neutral prone position for 5 min. The dynamic STM group received all elements of classic STM followed by distal to proximal longitudinal strokes performed during passive, active, and eccentric loading of the hamstring. Only specific areas of tissue tightness were treated during the dynamic phase. Hamstring flexibility was quantified as hip flexion angle (HFA) which was the difference between the total range of straight leg raise and the range of pelvic rotation. Pre- and post-testing was conducted for the subjects in each group. A one-way ANCOVA followed by pairwise post-hoc comparisons was used to determine whether change in HFA differed between groups. The alpha level was set at 0.05. RESULTS: Increase in hamstring flexibility was significantly greater in the dynamic STM group than either the control or classic STM groups with mean (standard deviation) increase in degrees in the HFA measures of 4.7 (4.8), -0.04 (4.8), and 1.3 (3.8), respectively. CONCLUSIONS: Dynamic soft tissue mobilisation (STM) significantly increased hamstring flexibility in healthy male subjects.

Adolescent↗

PubMed2000

Changes in the excitability of the H-reflex in wrist flexors related to the prone or supine position of the forearm in man.

The effect of the forearm position, prone vs. supine, on the excitability of the H-reflex in flexor carpi radialis (FCR) muscle was tested in nine adult volunteers by comparing the recruitment profiles of the H and M waves. The H-reflex size, normalized to the maximal M response, was lower when the forearm was supine than when it was prone, with an average reduction of about 50% over most of the H-recruitment curve. In three wrist positions, intermediate between prone and supine, the amount of reflex attenuation was related to the prono-supination angle. Control experiments excluded that the changes in the H reflex excitability were due to displacements of the stimulating or recording electrodes.

Adult↗

PubMed2006

Bowel preparation for CT-colonography: comparison of two different cleansing protocols.

OBJECTIVE: Comparison of cleansing effects and colonic distension observed with two polyethyleneglycol-solution (PEG) containing bowel preparation techniques prior to CT-colonography (CTC). MATERIALS AND METHODS: One hundred and three patients that received CTC in our institution were retrospectively evaluated. Fifty-one patients received preparation 1 (BP1; based on a GoLytely formulation+bisacodyl), 52 preparation 2 (BP2; based on a NuLytely formulation+bisacodyl). On multi-planar-reformatted (MPR) images, fluid residuals and colon distension were assessed in five colonic segments, from the ascending colon to the rectum. RESULTS: On average, significantly (p<0.001) lower fluid residuals were assesses when using BP2 regardless of the patient position. In prone position, a significantly lower fluid level was observed in the sigmoid using bowel preparation 2. The average maximum diameter measured for the whole colon was 5.2+/-0.6 cm in prone position and 4.8+/-0.6 cm in the supine position in BP1 (p<0.01). In BP2 the average maximum diameter measured for the whole colon was 5.3+/-0.6 cm in prone position and 4.7+/-0.5 cm in supine position, respectively (p<0.001). CONCLUSION: Overall, lower fluid residuals were scored using BP2. In both preparation groups we achieved better colonic distension in prone position. We were not able to distend the sigmoid better when insufflating air during patient repositioning.

Bisacodyl↗

PubMed2002

Prevention of ventilatory disturbance while in the face-down position after macular hole surgery.

The aim of the present study was to assess the effects of the face-down position on ventilatory function after macular hole surgery. The transcutaneous carbon dioxide tensions (tcPCO2) were measured in five patients who had undergone intraocular tamponade and in 17 normal subjects. The tcPCO2 measurements were done in patients following vitrectomy in the sitting position and in the prone position with their faces down over the semi-closed spaces of the conventional mats. In normal subjects, minute ventilatory volumes (V.E) were measured simultaneously with tcPCO2 in the sitting position and prone position. The newly introduced face-down mats (new mats) for the prone position were also tested in the normal subjects. In normal subjects, VE in the prone position with the conventional mats was significantly lower than that found in the sitting position (5.06 +/- 1.55 vs 6.06 +/- 1.64 L/min; P < 0.002). The tcPCO2 in the prone position was significantly higher than that in the sitting position (41.7 +/- 2.1 vs 38.0 +/- 1.9 mmHg; P < 0.0001). In post-vitrectomy patients, tcPCO2 in the prone position with the conventional mats was significantly higher than that in the sitting position (41.4 +/- 1.7 vs 38.6 +/- 2.2 mmHg; P < 0.02). The tcPCO2 in the prone position in normal subjects was significantly lower using new mats than that when using conventional mats. The use of conventional mats during a prone position, increased the tcPCO2 values when compared to the tcPCO2 values obtained during the sitting position in patients following vitrectomy. This could be due to either a decrease of the VE caused by limited thoracic movement or rebreathing of the exhaled gas over the semi-closed space, or both. The new mats might be useful in alleviating the increase of tcPCO2 by eliminating the rebreathing of the exhaled gas.

Aged↗

PubMed2002

Three-dimensional intrafractional movement of prostate measured during real-time tumor-tracking radiotherapy in supine and prone treatment positions.

PURPOSE: To quantify three-dimensional (3D) movement of the prostate gland with the patient in the supine and prone positions and to analyze the movement frequency for each treatment position. METHODS AND MATERIALS: The real-time tumor-tracking radiotherapy (RTRT) system was developed to identify the 3D position of a 2-mm gold marker implanted in the prostate 30 times/s using two sets of fluoroscopic images. The linear accelerator was triggered to irradiate the tumor only when the gold marker was located within the region of the planned coordinates relative to the isocenter. Ten patients with prostate cancer treated with RTRT were the subjects of this study. The coordinates of the gold marker were recorded every 0.033 s during RTRT in the supine treatment position for 2 min. The patient was then moved to the prone position, and the marker was tracked for 2 min to acquire data regarding movement in this position. Measurements were taken 5 times for each patient (once a week); a total of 50 sets for the 10 patients was analyzed. The raw data from the RTRT system were filtered to reduce system noise, and the amplitude of movement was then calculated. The discrete Fourier transform of the unfiltered data was performed for the frequency analysis of prostate movement. RESULTS: No apparent difference in movement was found among individuals. The amplitude of 3D movement was 0.1-2.7 mm in the supine and 0.4-24 mm in the prone positions. The amplitude in the supine position was statistically smaller in all directions than that in the prone position (p < 0.0001). The amplitude in the craniocaudal and AP directions was larger than in the left-right direction in the prone position (p < 0.0001). No characteristic movement frequency was detected in the supine position. The respiratory frequency was detected for all patients regarding movement in the craniocaudal and AP directions in the prone position. The results of the frequency analysis suggest that prostate movement is affected by the respiratory cycle and is influenced by bowel movement in the prone position. CONCLUSION: The results of this study have confirmed that internal organ motion is less frequent in the supine position than in the prone position in the treatment of prostate cancer. RTRT would be useful in reducing uncertainty due to the effects of the respiratory cycle, especially in the prone position.

Fluoroscopy↗

PubMed2001

Evaluation of transesophageal atrial pacing in the prone and lateral positions.

OBJECTIVE: To develop recommendations for positioning the second-generation pacing esophageal stethoscope for transesophageal atrial pacing in patients positioned prone (P), right lateral decubitus (RLD), and left lateral decubitus (LLD). DESIGN: Prospective; patients assigned consecutively. SETTING: Tertiary and university hospitals. PARTICIPANTS: Thirty (10 in each position group) adult patients undergoing surgery. INTERVENTIONS: The optimal depths of insertions (DOI) where pacing current threshold was minimal (THmin) were determined first when supine, then after positioning. MEASUREMENTS AND MAIN RESULTS: Transesophageal atrial pacing was successful in all patients supine and after positioning. The optimal DOI varied from 2 cm less deep to 4 cm deeper in positioned patients compared with supine patients. Patients positioned P required equal or up to 8 mA greater current outputs to achieve transesophageal atrial pacing; LLD and RLD patients may require up to 8 mA greater or lesser current compared with supine patients. CONCLUSION: Transesophageal atrial pacing can be used safely and effectively in patients positioned P, RLD, and LLD. Recommendations are presented for positioning the pacing esophageal stethoscope. Emphasis is given to using the lowest DOIs and smallest currents to reduce the chance of transesophageal ventricular pacing.

Adolescent↗

PubMed1980

Effect of body position and of respiratory frequency on distribution of pulmonary ventilation and perfusion in dogs.

Ventilation (VA) perfusion (Q) ratios distribution measured by the inert gases method is studied in 7 anesthetized dogs in supine position, in prone position at a respiratory frequency of 15 cpm, and in prone position at a respiratory frequency of 10 cpm so as to test the sensitivity of this VA/Q method. Despite the fact that the precise height-width characteristics of the distribution modes are unknown, our results show coherent changes and sensitivity of the log standard deviation of the perfusion curve, of the shunt, and of the dead space obtained with the inert gas method. After the change from supine to prone position, cardiac output increases, shunt, if it exists, diminishes, VA/Q ratios distribution becomes more uniform, and PaO2 increases and (A-a)DO2 decreases. When respiratory frequency changes from 15 to 10 cpm, cardiac output, shunt, and dead space decrease, VA/Q ratios distribution curves are slightly less homogeneous. PaO2 and PaCO2 show no significant variation. This study shows that distribution mode's characteristics can be considered as good and coherent approximations.

Animals↗

PubMed1994

[Effects of different positions for epidural block on skin-epidural space distance].

Epidural block was performed in the same intervertebral space by both approaches with either flank position or prone position under fluoroscopy. The distances from with both positions the skin to the epidural space (SED) were compared. The prone position approach under fluoroscopy resulted in a significantly greater SED in both T2/3 puncture and L4/5 puncture groups. This was assumed to be due to the fact that the prone position approach does not always allow minimum distance. It was also thought to be due to the fact that in this position, compared with the flank position, a pillow is inserted under the thoracic (or abdominal) region, and the skin in the dorsal region is looser and the subcutaneous tissue is thicker. The lumbar vertebrae form the lordosis, and it does not disappear when the pillow is placed under the abdominal region. This causes the SED to be greater.

Adult↗

PubMed1997

Posture and gastro-oesophageal reflux: a case for left lateral positioning.

AIM: Prone posture is often recommended for symptomatic gastroesophageal reflux in young infants, but prone positioning has been associated with sudden infant death. The aim of this study was thus to establish the optimal alternative posture for reducing reflux. METHODS: 24 infants (< 5 months) with symptomatic gastro-oesophageal reflux were studied prospectively with 48 h pH monitoring. They were randomly assigned to one of the 24 permutations of the four positions (supine, prone, right, left). During the first 24 hours the infant was held horizontally, and then the permutation was repeated at 30 degrees head elevation, giving a total of eight study segments for each infant. Data were edited to remove all time when the infants were not in the prescribed positions. Results were evaluated using analysis of covariance. RESULTS: Gastro-oesophageal reflux expressed as reflux index (mean % (SEM)) was significantly less in the prone and left lateral positions (6.72 (1.06) and 7.69 (1.03) respectively) than in the supine and right lateral positions (15.33 (2.33) and 12.02 (1.38); p < 0.001). Head elevation did not affect any variables significantly. CONCLUSIONS: Head elevation may not always be of clinical value. The left lateral position is a suitable alternative to prone for the postural management of infants with symptomatic gastro-oesophageal reflux.

Analysis of Variance↗

PubMed2002

Pneumonectomy in children.

OBJECTIVES: Surgical literature carries relatively scant information on pneumonectomy in children. We reviewed our experience over 7 years, determined the risk/benefit ratio and compared our experience with reports from the literature. METHODS: The records of children undergoing pneumonectomy, 14 years and younger, over a 7-year period from January 1991 to December 1997, are analysed, the techniques used to determine the need for and extent of surgery are studied, whilst the problems and outcome of surgery in this age group are determined. RESULTS: Fifty-nine children, 40 males, 19 females, aged 6 months to 14 years, average age of 7.5 years, underwent pneumonectomy. A history of pulmonary infection/s and a chest radiograph suggestive of lung destruction were indicators for investigation by bronchography and/or computerized axial tomography of the chest (HRCT scan). This determined the nature and extent of disease and the possibility and extent of surgery required. Bronchus blockers (22), five others in combination with the prone operating position, prone position (six) and a double lumen tube in one, were used to protect the healthy lung at surgery. Spill of pus was recognized once with a bronchus blocker and the prone position used in combination. Six intra-operative complications (10.1%) were recognized: bronchial spill (one) without consequence, conversion of bi-lobectomy to pneumonectomy due to pulmonary artery injury (one), cardiac arrest (with resuscitation, one), bradycardia with hypotension (one), excessive bleeding (one) and intra-pleural spill of debris (one), the last without consequence. Seven post-operative complications (11.8%) occurred: one empyema (sterilized), bleeding one, pulmonary infection two, suspected but unproven broncho-pleural fistulae two, prolonged antibiotics in one, reason unrecorded. One pneumonectomy through an empyema was uncomplicated. The main histological features were bronchiectasis (38), active tuberculosis (eight), end-stage lung (five), collapse and pulmonary haemorrhage (one), lobar emphysema (one). Histology unrecorded (one). No death occurred. All patients left hospital well. CONCLUSIONS: Careful preparation, often including anti-tuberculosis cover, and timing of pneumonectomy are essential. Meticulous anaesthetic and surgical technique and co-operation are critical. Bronchus blockers functioned well but are not without risk. Attention to detail makes pneumonectomy safe in childhood.

Adolescent↗

PubMed2003

Radiation therapy of the pelvic and paraaortic lymph nodes in cervical carcinoma: a prospective three-dimensional analysis of patient positioning and treatment technique.

PURPOSE: Pelvic box fields in prone position are the standard treatment for patients with cervical carcinomas. The issue investigated in this report is whether this technique should also be used when extending the planning target volume to the paraaortic region. MATERIALS AND METHODS: In a prospective study of eight consecutive patients with cervical carcinomas, two patient positions (prone and supine) and three radiation techniques (A, anteroposterior/posteroanterior opposed fields; B, four-field box; and C, three-field technique) were examined concerning the dose to critical organs. The analysis was based on three-dimensional planning, dose-volume histograms and normal tissue complication probabilities (NTCP). RESULTS: Compared to the prone position, the supine position led to improved organ sparing in four of seven organs (liver, both kidneys, spinal canal). In two of seven organs (rectum and bladder) no difference between prone and supine position was observed. The best sparing of small bowel was achieved in prone position. Technique B followed by technique C in the supine position resulted in the best overall sparing of critical organs concerning the volumes receiving the respective TD(5/5) doses or more. Mean NTCP values for liver, rectum and bladder were below 1.0%. The highest values of up to 12% were found for both kidneys in prone position with C and for the spinal canal with A in the prone and supine position. CONCLUSION: According to this analysis, for the treatment of the pelvic and paraaortic lymph node regions together, supine position and technique B (alternatively C) should be preferred despite the advantages of prone position on belly boards for pelvic irradiation alone.

Aorta, Abdominal↗

PubMed2006

Adult prone retroperitoneal partial nephrectomy: initial experience.

To our knowledge, we provide an initial description of an adult patient undergoing a retroperitoneal partial nephrectomy in the prone position. The prone position was chosen because of the posteromedial location of the patient's right kidney lesion. We describe our surgical methods and the potential pitfalls to this approach.

Carcinoma, Renal Cell↗

PubMed2004

Use of the prone oblique position in surgery for posterior fossa lesions.

BACKGROUND: The lateral suboccipital approach has been conventionally performed with the lateral, park-bench, or sitting position and the midline suboccipital approach has been performed in the prone position. We attempt to show the advantages of the prone oblique position in the surgery for posterior fossa lesions. METHODS: Twenty-two patients with posterior fossa lesions underwent surgery in the prone oblique position. The patients were fixed in the prone position while the operating table was rotated to raise the patient's shoulder. The surgeon sat beside the downward-shifted contralateral shoulder of the patient. With the lateral suboccipital approach, the neck of the patient was rotated to the side of the lesion. With the midline suboccipital approach, the neck was not rotated. FINDINGS: With the lateral suboccipital approach, this position spread the transverse axis of the suboccipital triangle and eliminated the interference of the patient's shoulder, providing an operative field that is wider than the lateral position or park bench position in all cases. With the midline suboccipital approach, this position enabled the surgeon to operate on lesions located in the upper half of the posterior fossa, such as fourth ventricular lesions or infratentorial lesions, without the need for a looking up posture with overhanging of the operative microscope. CONCLUSION: The prone oblique position offers the operator a panoramic view of the posterior fossa.

Adolescent↗

PubMed1991

Hemodynamics in the prone jackknife position during surgery.

We examined the hemodynamic changes occurring with prone jackknife positioning during colorectal surgery. The operative procedure was restorative proctocolectomy with ileal J-pouch anal anastomosis in five patients with adenomatosis coli and six patients with ulcerative colitis and anoabdominal resection of the rectum with colonic J-pouch anal anastomosis in eight patients with rectal cancer. Nineteen patients (10 men and 9 women aged 41 +/- 19 years) were monitored with arterial and Swan-Ganz catheters during positioning. Measurements were obtained in the supine and prone positions (1 minute, 3 minutes), and the jackknife position (1, 3, 5, and 10 minutes), as well as before and after adoption of the Lloyd-Davies position (1, 3, 5, and 10 minutes). Turning the patient from the supine position to the prone position resulted in a significant decrease in the cardiac index (CI). However, following head-down rotation, the CI increased and returned to the value seen in the supine position (p less than 0.05). Heart rate (HR) slowed and mean arterial pressure (MAP) increased in the prone jackknife position. We concluded that the extent of the changes in cardiac function presented no serious problems.

Adenoma↗