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Potentially beneficial cardiovascular effects of melatonin administration in women.

The cardiovascular effects induced by the daytime administration of melatonin (1 mg) were compared to those of placebo in 12 young women. In order to eliminate cardiovascular effects due to fluctuating endogenous sex steroids, all women were taking a fixed dose of monophasic contraceptive pill. In comparison to placebo, the administration of melatonin reduced, within 90 min, the pulsatility index of the internal carotid artery, evaluated by color Doppler ultrasound (P < 0.01), as well as both systolic and diastolic blood pressure evaluated in supine position (P < 0.01). Supine catecholamine levels were not significantly modified, but norepinephrine levels evaluated after 5 min of standing position were significantly reduced (P < 0.02). These data suggest that in women the administration of 1 mg of melatonin may exert beneficial effects on blood vessels.

Adult↗

[Hepatopulmonary syndrome].

The hepatopulmonary syndrome (HPS) is a reversible pulmonary insufficiency in association with liver disease, most frequently liver cirrhosis. The pathogenesis of HPS is poorly understood. HPS is characterized by arterial hypoxemia caused by intrapulmonary arteriovenous shunts or marked vasodilatation of the pulmonary vessels and ventilation-perfusion mismatch in the absence of intrinsic heart or lung disease. Typical clinical signs are dyspnea in the upright position which improves in supine position (platypnoe) and decrease of arterial pO2 in the upright position (orthodeoxia). The diagnosis of HPS is based on clinical features, arterial blood gas analyses in supine and upright position, contrast echocardiography and lung perfusion scanning. Arteriovenous fistula can be excluded by pulmonary angiography. There is no established medical treatment of HPS. New medical and noninvasive therapies, such as transjugular intrahepatic Stent-shunt (TIPS), lead to improvement of HPS. These treatment modalities need further elucidation. HPS was shown to be reversible after orthotopic liver transplantation (OLTx) in some cases. Severe HPS, therefore, may be an indication rather than a contraindication for OLTx.

Humans↗

The effect of posture and pH on solid and liquid oesophageal emptying.

Oesophageal emptying of solids and liquids has been assessed in normal subjects using radionuclide techniques. The solid bolus comprised a 10 g disc of cooked minced beef which was labelled with 160 microCi; 99m Tc macro-aggregated albumin (MAA). The liquid bolus consisted of 15 ml of water labelled with 300 microCi; 99m Tc. Studies were performed in the upright and supine positions and repeated after ingestion of 30 ml of 0.1 M HC1 diluted to pH 1.6. Solid and liquid assessments were performed separately with a scintillation camera positioned posteriorly. Subjects were instructed to swallow at the commencement of the test and at 15 s intervals subsequently, until the bolus entered the stomach. Oesophageal emptying in the supine position was significantly slower than emptying in the upright position. This was true for both solid and liquid emptying, in the neutral and in the acidified oesophagus. Emptying of a solid bolus did not appear to be influenced by oesophageal pH. However, emptying of a liquid bolus was significantly slower when the oesophageal pH was acid, for both the supine and upright positions. We conclude that the supine posture delays both liquid and solid oesophageal emptying. The presence of acid in the oesophagus at a pH of 1.6 delayed liquid emptying, but not solid emptying, from the oesophagus.

Adult↗

A simplified two-component model of blood pressure fluctuation.

We propose a simple moving-average (MA) model that uses the low-frequency (LF) component of the peroneal muscle sympathetic nerve spike rate (LF(spike rate)) and the high-frequency (HF) component of respiration (HF(Resp)) to describe the LF neurovascular fluctuations and the HF mechanical oscillations in systolic blood pressure (SBP), respectively. This method was validated by data from eight healthy subjects (23-47 yr old, 6 male, 2 female) during a graded tilt (15 degrees increments every 5 min to a 60 degrees angle). The LF component of SBP (LF(SBP)) had a strong baroreflex-mediated feedback correlation with LF(spike rate) (r = -0.69 +/- 0.05) and also a strong feedforward relation to LF(spike rate) [r = 0.58 +/- 0.03 with LF(SBP) delay (tau) = 5.625 +/- 0.15 s]. The HF components of spike rate (HF(spike rate)) and SBP (HF(SBP)) were not significantly correlated. Conversely, HF(Resp) and HF(SBP) were highly correlated (r = -0.79 +/- 0.04), whereas LF(Resp) and LF(SBP) were significantly less correlated (r = 0.45 +/- 0.08). The mean correlation coefficients between the measured and model-predicted LF(SBP) (r = 0.74 +/- 0.03) in the supine position did not change significantly during tilt. The mean correlation between the measured and model-predicted HF(SBP) was 0.89 +/- 0.02 in the supine position. R(2) values for the regression analysis of the model-predicted and measured LF and HF powers indicate that 78 and 91% of the variability in power can be explained by the linear relation of LF(spike rate) to LF(SBP) and HF(Resp) to HF(SBP). We report a simple two-component model using neural sympathetic and mechanical respiratory inputs that can explain the majority of blood pressure fluctuation at rest and during orthostatic stress in healthy subjects.

Adult↗

Effects of the prone position on gas exchange and hemodynamics in severe acute respiratory distress syndrome.

OBJECTIVES: To address the following issues regarding the use of prone position ventilation in patients with severe acute respiratory distress syndrome (ARDS): a) response rate; b) magnitude and duration of improved oxygenation in responders during a 12-hr trial and the consequences of returning to the supine position; c) effects of the prone position on gas exchange and hemodynamics; d) consequences of oxygenation in nonresponders; and e) effects of repeated prone position trials. DESIGN: Prospective, nonrandomized interventional study. SETTING: Medical intensive care unit, university tertiary care center. PATIENTS: Nineteen consecutive, mechanically ventilated patients (age 45+/-20 yrs, mean+/-SD) with ARDS and severe hypoxemia, defined as PaO2/FiO2 of < or = 150 with FiO2 of > or = 0.6 persisting for < or =24 hrs, and a pulmonary artery occlusion pressure of <18 mm Hg. INTERVENTIONS: Patients were turned prone for 2 hrs. Nonresponders were returned supine, but responders were maintained prone for 12 hrs before being returned to the supine position. The procedure was repeated on a daily basis in all patients, until inclusion criteria were no longer met or the patients died. MEASUREMENTS AND MAIN RESULTS: Hemodynamic, blood gas, and gas exchange measurements were performed at the following time points: a) baseline supine; b) after 30 mins prone; and c) after 120 mins prone. Additional measurements for nonresponders were taken after 30 mins supine. For responders, additional measurements were taken after 12 hrs prone and 30 mins supine. Patients were considered responders if an increase in PaO2 of > or = 10 torr (> or =1.3 kPa), or increase in the PaO2/FiO2 ratio of >20 occurred within 120 mins. Eleven (57%) patients responded to the prone position. There was no difference in initial baseline parameters between responders and nonresponders. After 30 mins, the prone position in responders increased PaO2 and decreased calculated venous admixture (Qva/Qt). This improvement was the maximal obtained, and was maintained throughout the 12-hr prone period. After 12 hrs prone, mean FiO2 had been lowered from 0.85+/-0.16 to 0.66+/-0.18 (p < .05). Thirty minutes after the patients were returned supine, PaO2, PaO2/FiO2, and Qva/Qt were not different from 12-hr prone values, and were improved in comparison with baseline supine values. There was no worsening of gas exchange or hemodynamics in nonresponders. After the initial trial, a total of 28 additional episodes of prone position ventilation were performed in nine of the 19 patients. Of the 24 additional episodes in the responders, there was a response in 17 (71%) of 24 episodes. In the four additional episodes in nonresponders, there was a response in only one (25%) of four episodes. Response was accompanied by the same beneficial effects on gas exchange and Qva/Qt and absence of effect on hemodynamics as in the initial trial. There was no worsening in gas exchange or hemodynamics in nonresponder trials. CONCLUSIONS: Based on the data from this study, the prone position can improve oxygenation in severely hypoxemic ARDS patients without deleterious effects on hemodynamics. This beneficial effect does not immediately disappear on return to the supine position. In our patients, an absence of response to this technique was not accompanied by worsening hypoxemia or hemodynamic instability. Repeated daily trials in the prone position should be considered in the management of ARDS patients with severe hypoxemia.

Adolescent↗

Milk of calcium in the inferior calyx of a hydronephrotic kidney in a tetraplegic patient - a diagnosis to be made before scheduling for extracorporeal shock wave lithotripsy.

STUDY DESIGN: A Case Report of renal milk of calcium in a tetraplegic subject. OBJECTIVES: To increase the awareness of renal milk of calcium in spinal cord injury (SCI) physicians. Renal milk of calcium contains a colloidal suspension of calcium crystals. Since upright views of the kidneys are not performed in tetraplegic subjects, the renal milk of calcium may be misinterpreted as renal lithiasis by routine radiography taken in supine position. SETTING: Regional Spinal Injuries Centre, Southport, England. METHOD: In a 41-year-old male with traumatic tetraplegia, X-ray of abdomen in supine position showed multiple opacities in the region of the left kidney. These radio opaque shadows were interpreted as renal calculi. Subsequently, computed tomography (CT) of the kidneys was performed. RESULTS: CT confirmed the presence of calculi in the mid-polar calyx. However, the density situated in the inferior calyx of the hydronephrotic left kidney exhibited a horizontal upper edge. This specific radiological finding as observed in the CT of kidneys, provided the clue to the presence of milk of calcium in the inferior calyx of the hydronephrotic left kidney. CONCLUSION: As plain film of the abdomen in standing position is not performed in SCI patients, physicians caring for SCI patients should have a high index of suspicion for renal milk of calcium. Prompt diagnosis of renal milk of calcium will help to avoid unnecessary surgery, or extracorporeal shock wave lithotripsy.

Adult↗

Acute lung injury: effects of prone positioning on cephalocaudal distribution of lung inflation--CT assessment in dogs.

PURPOSE: To quantify cephalocaudal gradient of lung inflation in acute lung injury in a dog model in prone versus supine position. MATERIALS AND METHODS: Experiments were performed in accordance with Guide for the Care and Use of Laboratory Animals, as approved by National Research Council (National Institutes of Health), and were approved by committee on care and use of animals in research at Seoul National University Hospital. After induction of acute lung injury with intravenous injection of oleic acid, dogs were randomized to be ventilated in either prone (n = 6) or supine (n = 6) position. Spiral computed tomography (CT) and hemodynamic measurement were performed sequentially on an hourly basis. Volume and mean attenuation of lung were measured quantitatively by using software to evaluate each CT section. Cephalocaudal gradient of mean lung attenuation, distribution of gas and tissue, and alveolar expansion were assessed. Functional residual capacity and net alveolar expansion of entire lung were measured. Statistical analysis was performed with Friedman, sign, and Mann-Whitney tests. RESULTS: Mean lung attenuation increased gradually from apex to base of lung in supine position. Thus, inflation gradient along cephalocaudal axis was found. Gas was located predominantly in upper lung, whereas tissue was dominant in lower lung in supine position. In supine group, cephalocaudal inflation gradient showed no significant change from baseline up to 4 hours. After prone positioning, cephalocaudal inflation gradient was reduced, and gas and tissue proportions became more uniform along cephalocaudal axis. In prone group, absolute values of cephalocaudal inflation gradient at time points of prone positioning for 1, 2, and 3 hours were significantly lower than baseline values (P < .05) and those in supine group (P < .05). Alveolar expansion occurred in caudal regions, and alveolar contraction occurred in cephalic regions; accordingly, net alveolar volume of entire lung was not altered significantly. Functional residual capacity was unchanged by prone positioning. CONCLUSION: In acute lung injury, prone positioning induced more uniform distribution of gas and tissue along cephalocaudal axis by reducing cephalocaudal inflation gradient.

Animals↗

Alveolar recruitment during prone position: time matters.

Alveolar recruitment is one of the beneficial effects of prone positioning in patients with ARDS (acute respiratory distress syndrome). However, responses vary among patients and, therefore, we hypothesized that alveolar recruitment is an individual time-dependent process and its measurement might be helpful to 'dose' prone positioning individually. In 13 patients diagnosed with ARDS, EELV (end-expiratory lung volume) was measured in the supine position, immediately after turning to the prone position, at 1, 2, 4 and 8 h in the prone position and after returning to the supine position. Responders were defined based on a 30% increase in oxygenation. EELV increased in responders, whereas it remained constant in non-responders. The time course was different in individual patients. In some responders, a plateau was reached as early as 2-4 h, whereas, in others, 8 h of prone positioning was not sufficient to allow complete recruitment. The increase in lung volume was associated with both an increase in arterial oxygenation and a decrease in venous admixture. Furthermore, responders had significantly lower baseline EELVs than non-responders. In conclusion, alveolar recruitment during prone positioning has been characterized as an individual time-dependent process. Its measurement might be useful to apply prone positioning more individually and might also help to identify responders.

Adult↗

[Changes of cervical blood flow in subjects with different tolerances to -30 degrees head-down bed rest].

In order to investigate characteristics of cervical blood flow in subjects with different tolerances to head-down tilt (HDT), 40 healthy men (aged 26-35 years) participated in the test of -30 degrees HDT for 45 min. During the test, mean blood flow velocities, diameters and blood flow volume of common carotid artery (CCA), Internal carotid artery (ICA), Internal jugular vein (IJV) were measured with color Doppler echogram. The results showed that there have different changes of in-flow of ICA and out-flow of UV between the adaptive subjects (n=33) and the inadaptive subjects (n=7). In the adaptive group, the cerebral blood flow volume during HDT, did not change from that during horizontal supine position. However, in the inadaptive group in-flow of ICA increased and out-flow of IJV decreased significantly during HDT as compared with those during horizontal supine position.

Adaptation, Physiological↗

[Hypotensive efficacy of verapamil alone and in combination with a diuretic in the treatment of essential hypertension in geriatric patients].

To evaluate the hypotensive efficacy of Verapamil alone and combined with diuretic, in the treatment of essential hypertension in elderly patients, we studied 54 patients, mean age 67.2 +/- 4.7 years, with essential hypertension, I-II WHO class. After a two-week wash-out from previous hypotensive therapies, patients were divided, at random, into three groups and, in double-blind conditions; they were treated as follows: the first group was treated with Verapamil (V) slow-release 240 mg/die, the second group with Chlorthalidone (C) 50 mg/die and the third group with the combination of Verapamil slow-release 240 mg/die and Chlorthalidone 50 mg/die (V + C). In the first group, the therapy (V) statistically reduced (p less than 0.001) either PAS or PAD values in supine position, (respectively -13 +/- 9 mmHg and -12 +/- 4 mmHg) and PAS-PAD values in upright position (respectively -16 +/- 3 mmHg and -10 +/- 3 mmHg). In the group treated with C, a statistically significant reduction (p less than 0.001) of PAS (-12 +/- 3 mmHg in supine position and -16 +/- 3 mmHg in upright position) and of PAD (-11 +/- 5 in supine and -9 +/- 4 mmHg in upright position). In the third group, V + C treatment induced a statistically bigger reduction of PAS and PAD (p less than 0.001) than that of the other two groups either in supine (-24 +/- 3 and -21 +/- 5 mmHg, respectively) or in upright position (-26 +/- 4 and -20 +/- 5 mmHg, respectively). Three patients interrupted the therapy for scarse compliance (I-II group).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

Effects of position on respiratory muscle function during CO2 rebreathing.

The effects of changing from the sitting to supine position on respiratory muscle function was assessed during CO2 rebreathing. Gastric (Pg), pleural (Ppl) and transdiaphragmatic (Pdi) pressures and thoracoabdominal motion were monitored. Diaphragmatic EMG was measured by a bipolar esophageal electrode and quantitated as a moving time average (EMGdi). From sitting to supine, in only 2 of 7 subjects (group A) the diaphragm gained a mechanical advantage as evident by an increased slope of the Pdi versus EMGdi relationship not present in the other 5 subjects (group B). At high levels of ventilation while sitting, only group B increased expiratory abdominal muscle activity leading to a more favorable diaphragm length and a passive descent of the abdomen-diaphragm on inspiration. In the supine position functional residual capacity progressively increased in all subjects and the above abdominal pattern was not seen. We conclude that during upright CO2 rebreathing the recruitment of the expiratory abdominal muscles assists diaphragmatic function by placing the diaphragm in an advantageous pressure generating configuration.

Abdominal Muscles↗

[Distension of the inter-facet joints in MRI: and indirect sign of an existing underestimation of spondylolisthesis and canal stenosis].

The authors present two observations of degenerative spondylolisthesis causing canal stenosis in which the stenosis was not apparent on MRI examination, due to reduction of spondylolisthesis in the supine position. In these cases, MR images of the facet joints showed unusual large areas with hypersignal on T2 weighted images suggestive of fluid collection. Observation of such images on supine MRI images should raise the suspicion of a spondylolisthesis existing on standing examination but reduced by the supine position, possibly leading to underestimating the canal stenosis.

Female↗

Displacements and strains in the costal diaphragm of the dog.

Radiopaque markers were attached at 1- to 2-cm intervals along three nearby muscle bundles to cover rectangular regions of the mid-costal diaphragms of seven dogs. The markers were tracked by biplane video fluoroscopy during spontaneous breathing (SB), mechanical ventilation with the same tidal volume (MV), and at inflation to total lung capacity (TLC) in the prone and supine positions. The three-dimensional positions of the markers at functional residual capacity (FRC), at end inspiration during SB and MV, and at TLC were determined, and the strains in the plane of the diaphragm relative to FRC were calculated. The principal strains were found to lie nearly along the muscle bundle direction and perpendicular to it. The principal strains along the muscle bundles, which describe muscle shortening, were uniform among the three bundles and uniform along the bundle for MV. For SB, in the prone and supine positions, shortening was approximately 30% greater in the middle of the bundle than near the central tendon and chest wall. Although the tidal volumes were the same for SB and MV, the shortening was larger for SB. The strains perpendicular to the bundle direction were not significantly different from zero. It appears that, for the loads that occur during tidal breathing, the diaphragm is inextensible in the direction perpendicular to the muscle direction. There is a very small displacement of the costal diaphragm at its insertion on the chest wall. The displacement at the central tendon is primarily a result of muscle shortening and rotation of the arc of the muscle around its insertion on the chest wall.

Animals↗

Influence of modifications in breast irradiation technique on dose outside the treatment volume.

PURPOSE: There is increasing interest in potential long-term effects of radiotherapy (RT) in patients treated for breast cancer, particularly those in whom long-term survival can be expected. The purpose of the present study was to determine the effects of treatment techniques, including patient positioning (supine vs. prone) on the absorbed dose in organs at a distance from the treatment volume in breast RT. METHODS AND MATERIALS: Dose distribution was studied in a Rando-Alderson phantom, modified with a simulated left breast of tissue-equivalent material. RT delivery was studied using 60Co and 6 MV x-ray beams, as well as electrons and a 192Ir source for tumor bed boost RT. Doses were measured in several organs and tissues of interest using LiF thermoluminescent dosimeters. Tangential breast RT was simulated using both supine and prone positioning. RESULTS: Peripheral doses generally decreased approximately exponentially with distance from the edge of the treatment field. Peripheral doses in various target organs were significantly higher for supine than for prone tangential breast RT (for 50 Gy prescribed dose): 0.50 Gy vs. 0.25 Gy for the upper abdomen, 0.05 Gy vs. 0.02 Gy for pelvic organs, 0.17 Gy vs. 0.08 Gy for active bone marrow, and 0.47 Gy vs. 0.12 Gy for ipsilateral lung (discounting lung in primary beam). CONCLUSIONS: The present study suggests that peripheral doses in several organs and tissues of interest can be reduced by 40 to 75% by prone tangential breast RT. These results may have implications for future strategies in the treatment of screen-detected breast cancer.

Abdomen↗

[Effect of continuous change in axial position in treatment of post-traumatic lung failure (ARDS). A clinical study].

In the treatment of posttraumatic adult respiratory distress syndrome (ARDS) so far no breakthrough has been achieved. In several cases of severe ARDS we have seen improvements of lung function by means of continuous body positioning. We therefore compared the effect of kinetic positioning (KIN) on lung function and hemodynamics in ARDS patients to conventional (KON) supine positioning. 22 ARDS patients with multiple trauma treated by supportive continuous body positioning (KIN) (KCI-Mediscus) and without continuous positioning (KON) were investigated daily. Pulmonary and systemic hemodynamics were determined on the basis of pulmonary artery catheter measurements. Oxygenation ratio (PaO2/FiO2) and pulmonary shunt (Qs/Qt,%) were calculated. Extravascular lung water (EVLW, ml/kg body weight) was determined by double indicator thermodilution technique. Total injury severity by injury severity score (ISS) was 29.6 +/- 6 points (KIN) and 31.6 +/- 5 points (KON). The oxygenation ratio (PaO2/FiO2) increased significantly from 140 +/- 45 (day 0) to 237 +/- 40 (p < 0.05) [day 5] (KIN), in KON patients no improvement (143 +/- 48 [day 0], 133 +/- 44 [ay 5]) was seen (p < 0.05 between groups). There were no significant changes of systemic hemodynamics between the groups or compared to day 0. Pulmonary shunt decreased significantly from 26.6 +/- 4% (day 0) to 12.5 +/- 2% (day 5) (p < 0.05) in KIN patients and was 36.6 +/- 6% at day 0 and 31.4 +/- 2% at day 5 in KON patients (p < 0.05 between groups). EVLW was 11.1 +/- 2 ml/kg body weight at day 0 and 9.4 +/- 1 ml/kg body weight at day 5 (KIN)-EVLW was 12.9 +/- 2 ml/kg body weight at day 0 and 17.4 +/- 3 ml/kg body weight at day 5 (KON) (not significant). We found no hemodynamic side effects from continuous body positioning. In ARDS-patients submitted to body positioning oxygenation and pulmonary shunt improved significantly and were significantly better compared to those with conventional supine positioning. Continuous body positioning appears to represent a promising supportive treatment regimen in posttraumatic ARDS.

Adolescent↗

[Changes in thorax-lung compliance during general anesthesia with mechanical ventilation in response to various intraoperative maneuvers].

BACKGROUND: The author evaluated and compared changes in the thorax-lung compliance (C) of the patients under general anesthesia and mechanical ventilation in response to various intraoperative maneuvers. METHODS: With ethics committee approval, 60 ASA physical status I and II patients undergoing elective surgery were studied. The author compared C on supine position with no maneuver as control, with C with cephalad liver retraction by the abdominal retractor (AR), pneumoperitoneum by intraabdominal pressure of 12 mmHg (LS), abdominal wall lift (AL), sternal splitting (SS), and sternum lift (SL) position (BMI<or=25kg x m(-2)). Following induction of anesthesia the parameters were measured and recorded. Patients were mechanically ventilated with a tidal volume of 9 ml x kg(-1) and a respiratory rate of 8 breaths per minutes. Statistical analysis was performed with ANOVA and P<0.01 was considered significant. RESULTS: In the AR and LS groups, C decreased significantly. In the AL, SS and SL groups, C increased significantly. CONCLUSIONS: The thorax-lung compliance of the AL, SS and SL maneuver groups were physiologically superior to supine position for normal weight patients and these maneuvers avoid derangement of pulmonary functions.

Aged↗

Minimal blood loss in patients undergoing radical retropubic prostatectomy.

The objective of this study was to evaluate blood loss in patients undergoing radical retropubic prostatectomy. Blood loss and operating time were evaluated in a series of 197 consecutive patients with prostate cancer who underwent radical retropubic prostatectomy by a two-surgeon team. The patients were positioned supine with the table flexed and the patient in about 35 degrees Trendelenburg position. Results were compared with those recorded for an earlier series of 40 patients operated in the supine position alone. The influence of parameters that might affect blood loss (peridural and hypotensive anesthesia, bilateral hypogastric artery clamping) was assessed in multivariate analyses. Since adoption of a Trendelenburg position with flexion of the hips, the mean intraoperative blood loss has decreased by 80%, to a low level of 260 cc; and transfusions have become exceptional (0.5%). The decrease in blood loss correlated with a decrease in operating time, which was reduced to an average of 90 minutes. Whereas epidural anesthesia decreased blood loss by a modest 27%, intraoperative blood pressure, bilateral hypogastric artery clamping, and nerve sparing had little or no significant effect. Patient position and the surgical skill of a two-man team can virtually eliminate the risk of blood loss during radical retropubic prostatectomy. There is thus no need always to resort to other procedures or to preoperative autologous blood donation.

Aged↗

Effect of position on the spread of buffered 2% chloroprocaine administered epidurally for the second stage of labor.

Increasing the pH of epidurally administered local anesthetics hastens their onset of action and improves the quality of neural blockade. The effect of body position on the epidural spread of alkalinized 2% chloroprocaine HCl for the second stage of labor has not been reported. We studied the epidural cephalad and caudad spread of 2% chloroprocaine buffered with sodium bicarbonate administered epidurally at the beginning of the second stage of labor. We randomly assigned 30 patients to one of two groups, each consisting of 15 patients. Group 1 received an epidural redose in the upright position, and the patients in group 2 received a redose in the supine position. There were no differences with respect to the sacral or cephalad spread. From the results of this study, we conclude that patients may receive epidurally administered 2% chloroprocaine late during the first stage of labor while in a supine position.

Adult↗