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We present a case of thoracoscopic bilateral lung volume reduction surgery performed with the patient in a supine position. By rotating the operative table, bilateral apical resection could be performed without difficulty. The duration of the operation was 160 minutes and the patient's forced expiratory volume in 1 second improved from 0.81 l to 2.49 l.
False-positive exercise test responses are frequently observed in women. To differentiate a false-positive from a true-positive test response, the effect of postures for recording a postexercise electrocardiogram to the recovery process of ST depression was investigated in 26 women with nonischemic ST depression and in 14 patients with typical angina pectoris. Exercise tests were performed twice, and the postexercise electrocardiogram was recorded while standing during the first test and in the supine position during the second test. In the false-positive test, maximal ST depression occurred immediately after exercise and showed a rapid recovery process in the early recovery phase. However, ST depression persisted without complete recovery, or increased in the late recovery phase as long as subjects were kept standing. In contrast, ST depression returned to the control level when subjects changed to the supine position after exercising. This discrepant pattern in the recovery process of ST depression by changing postures was not observed in the true-positive test results. Changing postures for recording postexercise electrocardiograms could be helpful in differentiating a false-positive response from a true ischemic response.
BACKGROUND: Contact pressure distribution patterns in the supine position in low-birth weight (LBW) neonates were analyzed by the use of a photoelastic method. METHODS: A total of 61 subjects (LBW neonates, mature (bodyweight > 2,500 g at birth) neonates, normal infants and Down syndrome (DS) infants) were selected for the study. Infants were placed on a photoelastic measuring table. Photoelastic images generated in the contact regions of the body were photographed with a camera and printed on monochrome paper. The coefficient of variation in the pressure distribution value (PcV) and the top and bottom ratio (mu) of the trunk at the center of pressure were calculated. RESULTS: The Pcv value was significantly lower in DS than LBW (P < 0.001), mature (P < 0.002) and normal infants (P < 0.01). The mu value in LBW and mature neonates was 48.9 and 50.2%, respectively. Normal infants had a mu value of 44.0%, which was significantly lower than that in LBW neonates. However, there was no significant difference between LBW and DS infants. CONCLUSIONS: Neurological impairment specifically affects the data obtained by photoelastic analysis.
OBJECTIVE: To study the difference between the dynamic responses of human body and human surrogate under 30 degrees supine position, and to discuss impact probability of substituting human body with human surrogate in impact tests. METHOD: Five volunteers experienced half-sine impact pulses, averaged 4.76, 8.96, 11.33 G, lasting for 40-60 ms on an impact tower. The human surrogate was exposed to half-sine impact pulses, averaged 6.77, 10.39, 16.93, 21.11, 24.98, 31.11 G, lasting for 40-60 ms, two times for each G level. ECG changes of the volunteers were continuously monitored before, during and after each impact. RESULT: Output responses at forehead and chest of human body and human surrogate increased with input increments. But there was obvious difference of the dynamic responses between human body and the surrogate to impact of low G levels. Heart rate of each volunteer had temporary increase during the process of impact, and returned to normal level soon after the impact. CONCLUSION: There is difference in a certain extend between the dynamic responses of human body and human surrogate. The ECG changes are induced mainly by mental stress during process of impact.
We report a case of post-operative rhabdomyolysis following transmandibular buccopharyngectomy without reconstruction in a patient remaining in the supine position throughout the procedure. Muscle compression induced by a cushion used during the procedure had probably contributed to the rhabdomyolysis. Outcome was favourable without acute renal failure. Prevention, early diagnosis and treatment are the keys to a successful recovery.
The influence of preoxygenation in the supine (n = 10) versus the 45 degrees head-up (n = 10) position on the duration of apnea leading to a decrease in arterial oxygen saturation to 95%, as monitored by pulse oximetry, was investigated in 20 women undergoing elective cesarean section at term of pregnancy. The results were compared with those obtained in a control group of 20 nonpregnant women. In the supine position, the average time to desaturation to 95% was significantly shorter in the pregnant group (173 +/- 4.8 s [mean +/- SD]) than in the control group of nonpregnant women (243 +/- 7.4 s). Using the head-up position resulted in an increase in the desaturation time in the nonpregnant group (331 +/- 7.2 s) but had no significant effect in the pregnant group (156 +/- 2.8 s). We conclude that pregnant women desaturate their arterial blood of oxygen more rapidly than do nonpregnant women. Furthermore, the head-up position extends the duration of apnea that can take place before desaturation occurs in nonpregnant patients.
We performed a single stage video-assisted thoracoscopic surgery for bilateral spontaneous pneumothorax in the supine position with both arms abduced and the back slightly elevated using a pillow. While intercostal spaces were not open enough to insert a trocar, this procedure, not requiring the trouble of placing patients in the lateral decubitus position, is beneficial for the single treatment of bilateral thoracic discase.
The authors advise on an exceptional complication in a totally implantable venous access and give recommendations on how to avoid this problem. In an obese person, one week after the implantation of a totally implantable venous access, a chest X-ray showed that the catheter was too short. In the operative room, at the time of the second intervention, the radioscopy did not find this anomaly. The subcutaneous injection port was positioned too low. When the patient was in a supine position, the subcutaneous injection port was in the correct position but when she was in an upright position, the breast descended and pulled down the subcutaneous injection port and the catheter.
Tension pneumocephalus is a rare and severe complication appearing after posterior fossa procedures in the sitting position. This complication may endanger the patient's life and require immediate treatment. However, tension pneumocephalus after neurosurgical procedure in the supine position have been scarcely reported. We report such a complication occurring in a 14-year-old girl submitted to a frontotemporal craniotomy for removal of an astrocytome performed with the patient supine. We discuss ethiopathogenesis and management of this complication.
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Tension pneumocephalus has been reported most frequently after posterior fossa surgery performed in the sitting position. We present a paediatric patient who developed tension pneumocephalus in the postoperative period after decompression of a craniopharyngioma performed with the patient in the supine position.
To assess the value of dynamic gadolinium-enhanced MR imaging combined with magnetization transfer contrast (MTC) of breast cancer by SPGR sequence, 15 patients with breast cancer were imaged in the supine position with the newly developed breast coil in a 1.5 Tesla imager. Dynamic gadolinium-enhanced MR imaging combined with MTC (10 cases) and conventional dynamic gadolinium-enhanced MR imaging (5 cases) were performed after the administration of Gd-DTPA (0.2 ml/kg). Sagittal images were obtained every 22 seconds during the first 264 seconds. Thus, a total of 15 images were obtained in each lesion. The signal intensity ratio (SIR) of lesion to mammary glarid was calculated for each image as follows: (SI lesion/SI mammary gland)/(SI (pre)lesion/SI (pre)mammary gland). Dynamic gadolinium-enhanced MR imaging with MTC always allowed better SIR at 88 seconds than conventional dynamic gadolinium-enhanced MR imaging after bolus injection (p < 0.01). Dynamic gadolinium-enhanced MR imaging with MTC improved detection of the boundary of the lesion and mammary gland.
Because of the prevalence of supine posture and sleep deprivation in both health and disease, we wondered how each of them influences prolonged maximal voluntary ventilation (MVV). Accordingly, we compared 12-second, 1-min, and 10-min isocapnic MVV supine with that measured in the upright posture in 8 healthy subjects. MVV decreased 6-10% supine, independent of test duration (p less than 0.01). Although end-expiratory lung volume was 0.47 liter lower during supine resting breathing (p less than 0.001), end-expiratory lung volumes during short-term MVV maneuvers were identical. To investigate any additional effect on MVV due to sleep loss, 12 healthy subjects performed 12-second, 1-min, and 30-min isocapnic MVV maneuvers in the supine position, either after normal sleep or after a 24-hour sleepless period. Sleep deprivation reduced MVV by 7-14%, again independent of test duration (p less than 0.05). Sleep loss also reduced the ventilation chosen to represent a submaximal (75%) breathing effect (p = 0.05), and it increased subjective ratings of fatigue and confusion (p less than 0.01). We conclude that supination and sleep deprivation together decrease both short- and long-term MVV by nearly 20%, with impairment of supination not caused by lung volume changes, and with the sleep loss effect occurring in tandem with a rise in the subjective assessment of breathing effort.
Mechanisms involved in the control of arterial pressure during postural changes were studied by analysis of the dynamic time course of cardiovascular changes during head-up tilt (HUT) and tilt back to supine position (TB). Beat-to-beat values of cardiovascular variables were recorded continuously before, during, and after passive HUT to 30 degrees in seven healthy humans. Left cardiac stroke volume (SV, Doppler ultrasound), mean arterial blood pressure (MAP), heart rate (HR), cardiac output (CO), and total peripheral conductance (TPC) were recorded. During HUT, MAP at the level of the carotid baroreceptors decreased by approximately 5 mmHg. There was a striking asymmetry between the time courses of cardiovascular changes on HUT and on TB. Adjustments generally took up to 30 s after HUT, whereas most changes were completed during the first 10 s after TB. Cardiovascular reflex adjustments of HR and TPC were more symmetrical. After HUT, SV was maintained during the first 4-6 s and then decreased steadily during the next 30 s to a stable level approximately 25% below its pretilt value. However, after TB, SV increased rapidly to its pretilt value in <10 s. This asymmetry in SV dynamics may be explained in part by a more rapid change in left cardiac filling after TB than after HUT. On TB, there must be a rapid inflow of stagnant blood from the legs, whereas venous valves will impede backward filling of veins in the lower body on HUT. In conclusion, we have revealed a characteristic asymmetry in cardiovascular responses to inverse variations in gravity forces in humans. This asymmetry can be explained in part by nonlinear, hydrodynamic factors, such as the one-way effect of venous valves in the lower part of the body.
BACKGROUND AND AIM: Bioelectrical impedance analysis is used to assess human body composition. Studies have shown that meal ingestion and change of body posture affects bioelectrical impedance, but none has studied bioelectrical impedance variation in supine subjects. The aim was to examine the bioelectrical impedance variation in healthy subjects during 12 h in the supine position. METHODS: Bioelectrical impedance was measured 16 times during 12 h in 18 healthy subjects. An identical meal was given at breakfast, lunch, and dinner. RESULTS: Mean (standard deviation) impedance at 50 kHz increased from 558 (87) omega at study start to 584 (95) Omega at study end (P<0.05). Bioelectrical impedance is reduced after ingestion of the first meal, but not following the meals at 1230 and 1730. Calculated body fat content increased from a baseline mean (SD) of 21.7 (6.1) % body fat to 23.9 (6.7) % body fat at study end (P<0.05). CONCLUSIONS: Bioelectrical impedance increased during 12 h in supine subjects. The increase is probably explained by a shift in body fluids from the extremities to thorax during the day and the importance of strict measurement standardisation both in epidemiological studies and clinical practice is underlined.
INTRODUCTION: Treatment of the morbidly obese patient with symptomatic renal calculi is an interesting urological challenge. Extracorporeal shock wave lithotripsy is frequently not possible for several reasons, and many urological centers match these patients as one of the residual indications for open surgery of kidney lithiasis. MATERIAL AND METHOD: Two patients with body mass index more than 50 k/m2 and symptomatic kidney stones were treated with percutaneous nephrolithotomy in the supine position described by Valdivia (slightly lateralized supine decubitus). Standard instrumentation for percutaneous surgery and the semi-rigid ureteroscopy were used, through an Amplatz sheath proximally transfixed with a polypropylene stitch, so to avoid its lost under the fatty skin. Both patients were rendered stone-free without significant morbidity. DISCUSSION: The advantages of Valdivia position in those patients are clear, both for the commodity of the surgical team, -because time may be spared and help needed to mobilized the patient is less-, as well as for what concerns to the anesthesia, because cardio-respiratory restrictions created by a general anesthesia in prone are greater and more severe in the obese patient. This position seems to be more suitable than other ones recommended for percutaneous nephrolithotomy in the obese patients, such as prone decubitus on a surgical saddle, or lateral decubitus position, that may compromise the radiological control of the operation.
Forty patients undergoing metrizamide computed tomographic cisternography (MCTC) were prospectively evaluated for the relative merits of prone and supine positioning for the intracranial delivery of the subarachnoid contrast material. Twenty patients were prone and 20 supine when tilted head downward. The degree of opacification was deemed satisfactory or unsatisfactory in each case for the various ventricles and for the suprasellar, quadrigeminal, perimesencephalic, and cerebellopontine angle cisterns. The visualization of the suprasellar and perimesencephalic cisterns was much more often satisfactory using a prone delivery (p less than or equal to 0.05 by Fisher exact test). None of these structures was opacified significantly better with the patient supine. A prone delivery is therefore recommended for most of the common indications for MCTC.
We performed a prospective randomized study to determine blood loss differences between supine or lateral patient position, during surgery in elective total hip replacement. Between January and October 1996, 64 consecutive cases of total hip replacements were randomly scheduled for a procedure either in the supine or in the lateral position. Of the 56 cases evaluated, 29 were operated in the supine position (SP) and 27 in the lateral position (LP). The standardized implantations were performed without cement and the blood loss was measured. The calculated loss of Hb on the day of operation was 235 g Hb +/- 17 (mean +/- s.e.) in the SP group and 177 g Hb +/- 14 in the LP group, respectively, (unpaired t-test p = 0.01). The calculated loss of Hb after five postoperative days was 227 g Hb +/- 24 (mean +/- s.e.) in the SP group and 179 g Hb +/- 24 in the LP group, respectively, p < 0.2. The net loss of Hb after five postoperative days was calculated by subtracting all perioperative blood substitutions (Cellsaver, autologous and homologous blood) resulting in 340 g Hb +/- 21 (mean +/- s.e.) in the SP group and 272 g Hb +/- 21 in the LP group, respectively, p = 0.02. The blood loss in primary cementless total hip replacement surgery can be significantly reduced by performing the procedure in the lateral position compared to that in the supine position. The blood loss is limited to the day of operation, as indicated by the stable Hb-levels thereafter.