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At least 631 records · Page 35Linked to original sources
PubMed1997

[The effect of prone position in spinal surgery on respiration and circulation].

The effects of position change on respiration and circulation of 42 patients during spinal operations were investigated in this study. The results showed that, if the patient was placed on the operation position following the administration of the anesthesia, the changes of respiration (f, VT, MV) and circulation (SBP, HR) were significant (P < 0.01, 0.05). On the contrary, if the patient was placed in the operation position and then started the anesthesia, the respiratory and circulatory changes were comparatively stable (P > 0.05). The authors concluded that: 1. for the cases undergoing spinal operations, it is advisable to place the patient in the operation position first and then start the anesthesia; 2. for the critical cases, a tolerable position should be adopted; 3. during the adjustment of the position of the patient, the clavicle and the ilium should be used as the fulcrum so as to avoid driect contact of the chest and abdoment with the operation table, thus to minimze interference on the respiratory and circulatory functions.

Adult↗
PubMed2002

Effect of position, nitric oxide, and almitrine on lung perfusion in a porcine model of acute lung injury.

In a porcine model of oleic acid-induced lung injury, the effects of inhaled nitric oxide (iNO) and intravenous almitrine bismesylate (ivALM), which enhances the hypoxic pulmonary vasoconstriction on the distribution of regional pulmonary blood flow (PBF), were assessed. After injection of 0.12 ml/kg oleic acid, 20 anesthetized and mechanically ventilated piglets [weight of 25 +/- 2.6 (SD) kg] were randomly divided into four groups: supine position, prone position, and 10 ppm iNO for 40 min followed by 4 microg x kg(-1) x min(-1) ivALM for 40 min in supine position and in prone position. PBF was measured with positron emission tomography and H(2)15O. The redistribution of PBF was studied on a pixel-by-pixel basis. Positron emission tomography scans were performed before and then 120, 160, and 200 min after injury. With prone position alone, although PBF remained prevalent in the dorsal regions it was significantly redistributed toward the ventral regions (P < 0.001). A ventral redistribution of PBF was also obtained with iNO regardless of the position (P = 0.043). Adjunction of ivALM had no further effect on PBF redistribution. PP and iNO have an additive effect on ventral redistribution of PBF.

Acute Disease↗
PubMed1998

Ischaemic optic neuropathy after spinal fusion.

PURPOSE: We report a case of ischaemic optic neuropathy which occurred after prolonged spine surgery in the prone position in an obese, diabetic patient. CLINICAL FEATURES: The patient was a 44-yr-old, 123 kg, 183 cm man for decompressive laminectomy and instrumented fusion of the lumbar spine. Anaesthesia was induced with thiopentone, fentanyl and succinylcholine and maintained with nitrous oxide, oxygen, isoflurane and a fentanyl infusion. He was positioned prone on the Relton-Hall frame and had an uneventful intraoperative course. Estimated blood loss was 3,000 ml. He was taken to the surgical intensive care unit (SICU) and the trachea was extubated 3.5 hr later. He had no pulmonary or haemodynamic problems and went to a regular nursing floor in the morning. He was discharged home on postoperative day #5. He telephoned his surgeon on postoperative day #7 to say that his vision had been blurry since surgery. His visual acuity was decreased, and on examination, he had a bilateral papillary defect, optic swelling and a splinter haemorrhage in the right eye. Magnetic resonance imaging (MRI) scan of the head and orbits detected no other abnormality. Based on this examination, he was felt to have bilateral ischaemic optic neuropathy and treated conservatively. By postoperative day #47, his visual acuity was greatly improved and near normal. Careful review of possible contributing factors suggests that the cause of the ischaemic optic neuropathy was venous engorgement. CONCLUSION: This patient developed ischaemic optic neuropathy from a prolonged interval in the prone position of the Relton-Hall frame, which may be related to venous engorgement.

Adult↗
PubMed1983

[The significance of dural sinus pressure in neurological surgery-- correlation with surgical position].

A study was made of the significance of confluens sinus pressure in various surgical positions and of various factors influencing confluens sinus pressure. The following findings were obtained: Confluens sinus pressure in various positions was follows: Reverse jackknife position (supine position with upper and lower halves of the body elevated ca 20 degrees) 1.3 +/- 0.8 (Mean +/- SD) cmH2O Sea lion position (prone position with upper and lower halves of the body elevated ca 10 degrees with neck hyperextended) 2.7 +/- 0.6 cmH2O Prone position 5.8 +/- 0.9 cmH2O Supine position 5.9 +/- 1.7 cmH2O Right lateral position 6.9 +/- 0.7 cmH2O Left lateral position 9.6 +/- 1.2 cmH2O Since confluens sinus pressure is strongly affected by gravity, the determination point, the height of the right atrium, and the central venous pressure were referred to when measuring the surgical position. When the upper half of the body was raised (at angle ranging from--10 degrees to +90 degrees) confluens sinus pressure became zero in adults when the angle was +25 degrees or thereabouts. When the angle was +90 degrees, a marked negative pressure of -12.7 +/- 3.0 cmH2O, was observed, suggesting the danger of air embolism. In 4 children under 6 years of ago, however, negative pressure was not observed even at an angle of +90 degrees, although some changes due to different angles were noted. This suggests some specificity of dural sinus pressure. Intrathoracic negative pressure at inspiration, the contraction of skeletal muscles, and profuse hemorrhage, and sympathetic nervous strain were surmised as other factors influencing dural sinus pressure.

Adult↗
PubMed1983

Dural sinus pressure as related to neurosurgical positions.

Taking advantage of the exposure of dural sinuses during craniotomies, we measured confluens sinuum pressure by direct catheterization. The influence of various surgical positions and of other factors on confluens sinuum pressure was studied. When the upper half of the body was raised, the confluens sinuum pressure decreased to reach zero at +25 degrees; when the angle was +90 degrees, a marked negative pressure of -12.7 +/- 3.0 cm H2O (mean +/- SD) was observed in adults. In children under 6 years of age, however, such negative pressure was not observed even at an angle of +90 degrees. The confluens sinuum pressure was 2.7 +/- 0.6 cm H2O with the patient in the reverse jackknife position (supine position with the upper and lower halves of the body elevated ca. 20 degrees), 3.0 +/- 0.8 in the sea lion position (prone position with the upper and lower halves of the body elevated ca. 20 degrees and with the neck hyperextended), 5.8 +/- 0.9 in the prone position, and 5.9 +/- 1.7 in the supine position. In the supine and the sitting positions, the confluens sinuum pressure was elevated well enough by jugular compression to prevent air embolism. Positive pressure respiration did not raise the confluens sinuum pressure. The pressure of the jugular bulb measured by percutaneous direct puncture did not always reflect the confluens sinuum pressure, probably because subcutaneous hematoma produced an effect similar to that of jugular compression.

Adolescent↗
PubMed1997

Efficacy of a belly board device with CT-simulation in reducing small bowel volume within pelvic irradiation fields.

PURPOSE/OBJECTIVE: Acute and chronic small bowel toxicity associated with pelvic irradiation limits dose escalation for both chemotherapy and radiotherapy for rectal cancer. Various surgical and technical maneuvers including compression and belly board devices (BBD) have been used to reduce small bowel volume in treatment fields. However, quantitative dose volume advantages of such methods have not been reported. In this study, the efficacy of BBD with CT-simulation is presented with dose-volume histogram (DVH) analyses for rectal cancer. METHODS AND MATERIALS: Twelve consecutive patients referred to our department with rectal cancer were included in this study. Patients were given oral contrast 1.5 h prior to scanning and instructed not to empty their bladder during the procedure. The initial CT scan without BBD was taken in the prone position with an immobilization cast. A second CT study was performed with a commercially available BBD consisting of an 18-cm thick hard sponge with an adjustable opening (maximum 42 x 42 cm2). All patients were positioned prone over the BBD so that the opening was above the treatment volume and usually extended from the diaphragm to the bottom of the fourth lumbar spine. Image fusion between both sets of CT scans (with and without BBD) was performed using common bony landmarks to maintain the same target volume. The critical structures including small bowel and bladder were delineated on each slice for DVH analysis. On each study, a three-field optimized plan with conformal blocks in beams-eye-view was generated for volumetric analysis. The DVHs with and without BBD were evaluated for each patient. RESULTS: The median age and body weight of 12 patients (4 females and 8 males) were 57.5 years and 82.7 kg, respectively. The changes in posterior-anterior (PA) and lateral separation with and without BBD at central axis slices were analyzed. The changes in lateral separation were minimal (<0.8 cm); however, the PA separation was reduced by 11.3 +/- 3.3% when BBD was used. The reduction in PA separation was directly related to the reduction in small bowel volume. The small bowel volume was significantly reduced with a median reduction of 70% (range 10-100%) compared to the small bowel volume without BBD. The small bowel volume reduction did not correlate either with body weight, age, gender, or sequence of radiation treatment with surgery (pre-op vs. post-op). The DVH analysis of small bowel with BBD showed significant volume reduction at each dose level. For 50% patients, the DVH analysis demonstrated an increase in bladder volume with BBD. All patients treated with the BBD completed their treatment without any break and without significant acute gastrointestinal or genitourinary toxicity. CONCLUSIONS: For rectal cancers, small bowel is the dose-limiting structure for acute and chronic toxicity. The use of the BBD should improve the tolerance of aggressive combined modality treatment by reducing the small bowel volume within the pelvis compared to the prone position alone. The BBD provides an easy, economical, comfortable, and noninvasive technique to displace small bowel from pelvic treatment fields. The small bowel volume is dramatically reduced at each dose level. The volume reduction does not correlate with gender, age, weight, pelvic separation, and sequence of radiation treatment vs. surgery.

Aged↗
PubMed2005

Anterior ischemic optic neuropathy complicating cranial vault reconstruction for sagittal synostosis in a child.

The authors report a case of postoperative visual loss in a pediatric patient who underwent an uneventful cranial vault reconstruction. A 5-year-old boy underwent total cranial vault reconstruction for nonsyndromic sagittal synostosis. He was positioned prone for 6 hours and then supine for the final 2 hours of surgery. Controlled hypotension was used to maintain the systolic arterial pressure at 80 mmHg to 90 mmHg. The intraoperative hematocrit was 23% to 31%. In the immediate postoperative period, both pupils were noted to be reactive to light. After an uneventful night in the intensive care unit, he was transferred to the ward. The eyelids were edematous on postoperative day 1, and visual examination was no longer possible. He was discharged home on postoperative day 4, and readmitted 2 days later with bilateral blindness. The pupils were nonreactive, and the optic discs were pale and edematous. Computed tomography and magnetic resonance imaging of the head revealed no abnormality. Intravenous steroid therapy was initiated, and the patient was taken to the operating room for re-exploration; the intracranial pressure was found to be normal. The presumed diagnosis was bilateral infarctions of the anterior optic nerves. Visual acuity 14 months after surgery was less than 3/200 in the right eye and 20/20-2 in the left, indicating significant recovery. Pediatric patients undergoing cranial vault reconstruction are at risk for postoperative visual loss because of ischemic optic nerve injury. Prolonged duration in the prone position and significant blood loss may be risk factors.

Blindness↗
PubMed2001

Test-retest reliability of the soleus H-reflex in three different positions.

PURPOSE: H-reflex has been clinically useful in the diagnosis of radiculopathies, developmental disorders, and measurement of motoneuron excitability. However, variability of the H-reflex precluded its routine application. The purpose of this study is to evaluate the test-retest and within-subject reliability of the soleus H-reflex tested in three different positions. SUBJECTS: Seven men and eight women healthy volunteered (20-50 y) with no history of significant low back pain or radiculopathy consented to the study. METHODS: The soleus H-reflexes for both lower extremities were elicited and recorded using Cadwell 5200-A EMG unit and surface recording. The tibial nerve was electrically stimulated at the popliteal fossa using 0-5 ms., 0.2 pps pulses at intensity equivalent to H-max. Each subject was tested randomly in three different positions: pronelying, free standing, and standing while lifting 20% of his/her body weight. Signal were amplified (1-5 K) using surface electrodes applied on the soleus muscle at midline and 3 cm below the gastrocnemius musculotendinous junction. The peak-to-peak amplitude and onset latencies of four separate traces were averaged for each trial. Subjects were re-tested within 10 days by the same tester following the same protocol. RESULTS: Test-retest reliability of the H-reflex amplitude ranged from r = .29 in prone position to r = .56 in the loading position. Within day reliability of the H-amplitude was high between the three different positions and ranged from r = .56 to r = .97. The test-retest reliability of the H-latency were extremely high and robust, with the coefficients ranged from r = .92 to r = .94. Also the within day reliability of the H-latency ranged from r = .96 to r = .99. CONCLUSIONS: Results indicated that, when the H-amplitude is the measure of choice, testing the H-reflex in standing and loading positions is more reliable than testing in pronelying. Also testing the subject during various procedures in the same session is more reliable than testing subject in different days/sessions. The H-latency is highly reliable in all three testing positions.

Adult↗
PubMed2004

"Back to sleep" and unexplained death in infants.

OBJECTIVE: Investigation of body position in infants with sudden and apparently unexplained death. Determination of the upper airway space of the infants in different positions by computed tomography (CT) scan. Comparison of the CT scan, the body position at death scene, and the autopsy results. DESIGN: Prospective investigation on all infants referred to a specialized center investigating abrupt and apparently unexplained death of infants. SUBJECTS: Full-term infants with sudden and clinically unexplained death. Four extra infants studied at different postmortem times to verify absence of change in measurement in postmortem CT scan over time. DATA COLLECTED: Position of infant when found dead. CT scan of upper airway in 3 positions (prone face down, prone head rotated, supine nose up), presence or absence of upper airway obstruction, level and length of the obstruction, presence or absence of cause of death, and presence or absence of small maxillomandibular complex at autopsy. RESULTS: Twenty-seven children had unexpected crib deaths (17 of them determined to be sudden infant death syndrome at autopsy). Fourteen children were found dead in the prone position; for 8 of them, this was their normal sleeping position. Airway occlusion behind the base of tongue was seen on CT scan in 24 of the 27 infants (89%) when placed prone head down; in 13 (48%) when placed prone with the head rotated to the side, and in 5 (18%) infants in the supine position. Four infants had mild facial dysplasia and had been found dead in the supine position; in 3 of them, sudden infant death syndrome was found to be the cause of death. The stability of CT scan findings over time was demonstrated after death in 3 different body positions. CONCLUSION: Supine sleeping position may not be necessarily protective when small jaws are present, and sleeping position may also be a factor in abrupt deaths in infants even if "explained by autopsy."

Airway Obstruction↗
PubMed2005

[Application of adjustable oblique position for microendoscopic discectomy].

OBJECTIVE: To compare the adjustable oblique position with prone position in microendoscopic discectomy (MED) and to evaluate its advantages. METHODS: One hundred and twenty-eight patients who underwent MED during August 2000 and August 2002 were studied. Forty-seven cases were positioned prone, 81 cases were positioned with adjustable oblique position. Operating time, blood loss and patient endurance were recorded and compared. The airway resistance of 29 lumbar disorder patients was measured when they were positioned supine, lateral and prone respectively after general anesthesia. RESULTS: There was statistically significant difference between 2 groups in operating time, blood loss and endurance. In prone position group, when operating time lasted for more than 50 min, 75% patients felt hurt on the skin of rib arch, and 38% patients presented dizzy and nausea. And all the patients had erythema on the rib arch. In the adjustable oblique position group, 3 cases had shoulder pain after operation, and 1 case had 4 days' common poroneal nerve paralysis. The airway resistance of patients with prone position was significantly higher than those with supine and lateral positioned patients. (P < 0.05). CONCLUSION: The adjustable oblique position in MED had the following advantages: (1) Do not limit the movement of chest and help reduce intra-abdominal pressure and epidural bleeding; (2) Give the lumbar spine the largest degree of flexion and the largest interlaminar space, which prevents injury of facet joint; (3) Increase posterior intervertebral space and make disectomy easier and exposure of nerve root and nerve root canal clearer; (4) The patients feel comfortable and can adjust the position of lumbar spine and lower extremity; (5) The monitor has the same direction with doctor, and it is easy for the doctor to operate; (6) Doctor can sit during operation.

Adolescent↗