Right Lateral Positions Research Articles

Small Volumes of Feed Can Trigger Transient Lower Esophageal Sphincter Relaxation and Gastroesophageal Reflux in the Right Lateral Position in Infants

To investigate the threshold amount of constantly infused feed needed to trigger lower esophageal sphincter relaxation (TLESR) in the right lateral position (RLP) and left lateral position (LLP). Eight healthy infants (3 male; gestational age: 32.9 +/- 2.4 weeks; corrected age: 36.1 +/- 1.3 weeks) were studied using an esophageal impedance-manometry catheter incorporating an intragastric infusion port. After tube placement, infants were randomly positioned in RLP or LLP. They were then tube-fed their normal feed (62.5 [40 to 75] mL) at an infusion rate of 160 mL/h. Recordings were made during the feed and 15 minutes thereafter. The study was repeated with the infant in the opposite position. More TLESRs were triggered in the RLP compared with LLP (4.0 [3.0 to 6.0] vs 2.5 [1.0 to 3.0], P = .027). First TLESR occurred at a significantly lower infused volume in RLP compared with LLP (10.6 +/- 9.4 vs 21.0 +/- 4.9 mL, P = .006). The percentage of feed infused at time of first TLESR was significantly lower in RLP compared with LLP (17.6% +/- 15.5% vs 35.4% +/- 8.02%, P = .005). In the RLP, TLESRs and gastroesophageal reflux are triggered at volumes unlikely to induce gastric distension.

Right lateral position does not affect gastric transit times of video capsule endoscopy: a prospective study

Video capsule endoscopy (VCE) examination of the small bowel is not complete in approximately 20% of the procedures. This fact limits its diagnostic yield. One of the main factors that influences the small-bowel transit time (SBTT) is the gastric transit time (GTT), ie, the interval in which the capsule stays in the stomach. It has been described that placing the patient in a right lateral position (RLP) after swallowing the capsule could decrease the GTT. To investigate whether the RLP, after the patient swallows the capsule, shortens the GTT and, secondarily, increases the rate of complete procedures. Randomized prospective study. Third-level hospital. Consecutive outpatients in whom VCE was indicated. Exclusion criteria were inpatients and previous gastric surgery. GTT for RLP 30 minutes after swallowing the capsule versus non-RLP (standing up position). The GTT, SBTT, and rate of complete procedures (examination of the entire small bowel). We did not observe significant differences in the GTT, the SBTT, and the complete procedures between groups. Only outpatients were included. RLP after swallowing the capsule does not influence either GTT nor the rate of VCE complete procedures.

Right lateral position improves complete examination rate of capsule endoscope: a prospective randomized, controlled trial

In 20% of patients, capsule endoscopes fail to reach the cecum within the 8-hour battery life. This is the most common cause of incomplete small-bowel examination. The aim of this study was to determine whether keeping patients in the right lateral position (RLP) improves the complete examination rate (CER) of the small bowel by reducing the gastric transit time (GTT) of the capsule. Patients were randomized into the RLP group (n = 30) or control group (n = 30). Patients in the RLP group were instructed to lie on their right side postingestion until the capsule had passed through the pylorus. The patients in the control group were free to walk or sit (upright position). The main outcomes were the CER and GTT between the groups. There was no significant difference in the sex, mean age, and indications between the two groups. The CER was significantly higher in the RLP group than in the controls (96.7% vs. 73.3%, P = 0.030). GTT was significantly shorter in the RLP group than in the control group (medians [range]: 32 [8-108] vs. 58 [9-208] minutes, P = 0.007). Small-bowel imaging time was significantly longer in the RLP group than in the control group (372 [135-425] vs. 292 [146-422] minutes, P = 0.039). There were no significant differences in the diagnostic yields between the two groups. Placing patients in the RLP after ingestion of the capsule endoscope and before the capsule enters the pylorus is a simple method to increase the CER of the small bowel by reducing the GTT of the capsule.

Right Lateral Position Improves Complete Examination Rate of Capsule Endoscope: A Prospective Randomized, Controlled Trial

Background and Aim: It has been reported that capsule endoscopes (CE) fail to reach the cecum in 20% of patients within the 8-hour battery life. The delayed gastric transit is the most common causes of incomplete small bowel examination. It's noted empirically that the gastric transit time (GTT) appeared to be decreased if patients were put in the right lateral position (RLP) post ingestion. The aim of this study was to determine whether RLP can improve complete examination rate (CER) of the small bowel by reducing the GTT of CE.

Effect of Body Position Changes on Postprandial Gastroesophageal Reflux and Gastric Emptying in the Healthy Premature Neonate

To identify a body-positioning regimen that promotes gastric emptying (GE) and reduces gastroesophageal reflux (GER) by changing body position 1 hour after feeding. Ten healthy preterm infants (7 male; mean postmenstrual age, 36 weeks [range, 33 to 38 weeks]) were monitored with combined esophageal impedance-manometry. Infants were positioned in the left lateral position (LLP) or right lateral position (RLP) and then gavage-fed. After 1 hour, the position was changed to the opposite side. Subsequently, all infants were restudied with the order of positioning reversed. There was more liquid GER in the RLP than in the LLP (median, 9.5 [range, 6.0 to 22.0] vs 2.0 [range, 0.0 to 5.0] episodes/hour; P = .002). In the RLP-first protocol, the number of liquid GER episodes per hour decreased significantly after position change (first postprandial hour [RLP], 5.5 [2.0 to 13.0] vs second postprandial hour [LLP], 0.0 [0.0 to 1.0]; P = .002). GE was faster in the RLP-first protocol than in the LLP-first protocol (37.0 +/- 21.1 vs 61.2 +/- 24.8 minutes; P = .006). A strategy of right lateral positioning for the first postprandial hour with a position change to the left thereafter promotes GE and reduces liquid GER in the late postprandial period and may prove to be a simple therapeutic approach for infants with GER disease.

Advantage of the Right Lateral Position Compared with the Lithotomy Position during the Perineal Procedure in Abdominoperineal Resection

Background/Aims: Abdominoperineal resection (APR) is generally performed in the lithotomy position (LT-APR). The aim of this retrospective study was to evaluate the advantage of the right lateral (RL) position during the perineal phase of APR, in extended APR (ext-APR) that needed additional excision of the pelvic organs and sacrococcyx, and in total pelvic exenteration (TPE). Methods: The present study is based on 50 patients observed from January 1993 to December 2004 (43 with primary rectal malignancy, 7 with recurrent cancer), who had undergone the following surgeries: LT-APR was carried out in 20 patients, RL-APR in 13, LT-ext-APR in 5, RL-ext-APR in 8, LT-TPE in 2 and RL-TPE in 2. Perioperative factors were compared between the LT and RL position in each operative procedure. Results: When RL-APR was compared with LT-APR, operative time (including the time to change the position) and the amount of operative blood loss were significantly less in RL-APR (mean ± SE = 314 ± 16 vs. 381 ± 18 min, p = 0.0156 and 598 ± 78 vs. 1,160 ± 171 g, p = 0.0168, respectively). The blood loss and operative time were also significantly less in RL-ext-APR than in LT-ext-APR (1,060 ± 170 vs. 3,590 ± 1,270 g, p = 0.0277 and 353 ± 31 vs. 488 ± 41 min, p = 0.0219, respectively). The average blood loss and operative time were 4,190 g and 650 min in LT-TPE, and 1,450 g and 609 min in RL-TPE, respectively. Conclusion: The RL position during the perineal phase following the abdominal phase in the LT position significantly decreases blood loss and operative time in APR and ext-APR.

The Effect of Patient Positioning on Complete Small Bowel Examination Rates with Wireless Capsule Endoscopy

Purpose: To evaluate (1) the effect on the gastric emptying time(GET), (2) the proportion of complete SI studies and (3) the diagnostic yield of WCE in patients placed in the right lateral position (RLP) compared with the standing/sitting position post CE ingestion (SSP). Methods: 67 consecutive studies in patients undergoing WCE for investigation of Obscure Gastrointestinal Bleeding (OGIB) from 9/03 – 9/04 were analyzed retrospectively. 9 patients were excluded, 5 (endoscopic placement of the CE), 3 (h/o gastric surgery), 1 (gastroparesis). Patients remained in the RLP or in the sitting/standing position for 30 mins post CE ingestion. Major findings were defined as ulcers, AVMs, strictures, and active bleeding. Results: The 58 remaining studies (31 men, 27 women, age range 16–80), included 35 patients from the RLP group and 23 from the SSP group. The mean GET (time from the first image of the stomach to the first image of the duodenum) in the RLP grp was 27 mins compared with 52 mins in the SSP grp(P < 0.05). The mean small intestinal emptying time was similar in both groups, RLP 207 mins and SSP 203 mins. Major findings were reported in 57% of the RLP grp and 43% of the SSP grp(NS). Stricturing of the SI precluding passage of the CE occurred in 4 cases and 1 case in the RLP and SSP grps respectively. 2 battery failures occurred in the SSP. Otherwise incomplete examinations of the SI were reported in 6% of the RLP grp and 9% of the SPP grp(NS). Conclusions: Positioning patients to the RLP facilitated passage of the CE into the SI without need for promotility agents and should be considered an initial option in the clinical setting. Although there was a numerical trend toward increased diagnostic yield and complete examations of the SI in the RLP grp these were not significant.

Assessment of oesophageal motor function using combined perfusion manometry and multi‐channel intra‐luminal impedance measurement in normal subjects

Multichannel intraluminal impedance (MII) is being used increasingly to assess oesophageal bolus clearance. However, there is no good standardization of the impedance parameters that define 'effective bolus clearance'. The aim of this study was to define these important impedance parameters and to determine their normal values. Concurrent perfusion manometry and MII were performed in 42 healthy volunteers. Ten, 5-mL liquid (saline) boluses and then, 10x5-mL low impedance viscous boluses were tested in each subject in the right-lateral position. Normal values for bolus presence time (BPT) at each site and total bolus transit time (TBTT) were determined from either 'normal' peristaltic responses (amplitude>or=30 mmHg in distal oesophagus) or 'super-normal' peristaltic responses (amplitudes>or=50 mmHg at all sites). The relationship between BPT and TBTT within a response and per-individual performance was determined. A total of 840 swallows of liquids and viscous responses were analysed. BPT and TBTT of viscous swallows were longer than those for liquids. Non-peristaltic responses were significantly more likely not to clear a viscous than a liquid bolus. Within a response, the number of sites with prolonged BPT strongly predicted the incidence of prolonged TBTT. Using impedance criteria, normal oesophageal bolus clearance is defined when an individual completely clears at least 70% of liquid responses and at least 60% of viscous responses. This study provides normal values for impedance measurement of bolus clearance when combined with perfusion manometry. These values will allow standardization of impedance application in oesophageal function testing, in both research and clinical setting.

Effect of Body Position on the 6‐Lead ECG of Dogs

ECGs recorded from dogs show characteristic morphology and changes in morphology with various disease states. These changes are determined by comparing individual recordings to reference ranges established from recordings obtained from normal dogs in right lateral (RL) recumbency. Using these reference ranges for ECGs recorded from dogs in other positions may not be valid. We compared ECG complexes from 39 normal dogs obtained in RL, left lateral (LL), and standing (ST) body positions. ECGs from dogs in ST position showed increased Q‐wave and R‐wave amplitudes in leads I and II, increased R‐wave and S‐wave amplitudes in leads aVR and aVL, and decreased R‐wave and S‐wave amplitudes in lead III when compared with recordings obtained in RL position. ECGs from dogs in LL position showed increased R‐wave amplitude in leads II, III, and aVF and S‐wave amplitude in lead aVL but decreased R‐wave amplitude in lead aVR when compared with recordings obtained in RL position. The mean electrical axis (MEA) shifted to the left in ST position but remained within the normal range in LL position. We determined that both a change in the relative position of the recording electrodes with respect to the heart as well as a change in intrathoracic cardiac position contributed to these changes. P‐wave amplitude, P‐R and S‐T intervals, and QRS complex durations remained unaltered by changes in body position. Our findings indicate that ECGs of dogs recorded in RL, LL, and ST positions yield dramatically different results, and investigators should use position‐specific reference ranges to minimize potential misinterpretation of ECG results.

Effect of body position on the 6-lead ECG of dogs.

ECGs recorded from dogs show characteristic morphology and changes in morphology with various disease states. These changes are determined by comparing individual recordings to reference ranges established from recordings obtained from normal dogs in right lateral (RL) recumbency. Using these reference ranges for ECGs recorded from dogs in other positions may not be valid. We compared ECG complexes from 39 normal dogs obtained in RL, left lateral (LL), and standing (ST) body positions. ECGs from dogs in ST position showed increased Q-wave and R-wave amplitudes in leads I and II, increased R-wave and S-wave amplitudes in leads aVR and aVL, and decreased R-wave and S-wave amplitudes in lead III when compared with recordings obtained in RL position. ECGs from dogs in LL position showed increased R-wave amplitude in leads II, III, and aVF and S-wave amplitude in lead aVL but decreased R-wave amplitude in lead aVR when compared with recordings obtained in RL position. The mean electrical axis (MEA) shifted to the left in ST position but remained within the normal range in LL position. We determined that both a change in the relative position of the recording electrodes with respect to the heart as well as a change in intrathoracic cardiac position contributed to these changes. P-wave amplitude, P-R and S-T intervals, and QRS complex durations remained unaltered by changes in body position. Our findings indicate that ECGs of dogs recorded in RL, LL, and ST positions yield dramatically different results, and investigators should use position-specific reference ranges to minimize potential misinterpretation of ECG results.

The detection of gaze direction: a stare-in-the-crowd effect.

A visual-search paradigm was used to explore the relative ease with which the direction of gaze can be detected. Straight-gaze stimuli were presented as targets within a variable number of distractors with left-averted or right-averted gaze. Reaction time in this case was compared with that when either the left-averted or right-averted gaze stimuli were the targets among distractors of the two remaining gaze directions. The data were examined for the existence of a search asymmetry favoring the straight-gaze targets. Such an asymmetry was found with stimuli that were realistically drawn renditions of pairs of human eyes, as well as with similar schematic stimuli representing pairs of human eyes. The asymmetry, however, was not found with geometric control stimuli, which also presented the critical feature in the central, the left-lateral, or the right-lateral position within the stimulus, but were not eyelike. It was also not found for schematic stimuli consisting of only one eye. It was concluded that the straight gaze direction is a special stimulus with eyelike stimuli, which the visual system is set up to process faster and with fewer errors than averted gaze directions. The results are discussed in terms of the evolutionary significance of the straight gaze direction.

PNEUMOPERICARDIOGRAPHY IN THE NORMAL DOG

To define the normal radiographic anatomy of the canine heart and pericardial space as outlined by air, pneumopericardiography was performed in ten normal, anesthetized dogs using a percutaneously introduced pericardial catheter. Room air was injected to produce pneumopericardiums without causing cardiac tamponade, and radiographs were obtained using a vertical beam with the dogs positioned in right lateral (RLAT), left lateral(LLAT), dorsal (VD), and ventral (DV) recumbency. Selective and nonselective angiocardiography was used to confirm the identity of the outlined structures. The RLAT and LLAT positions provided more information than the DV or VD positions. Pericardial air consistently outlined a distinct interventricular sulcus and the recesses around the aorta and pulmonary artery. The right auricle, outlined along the cranial heart border ventral to the ascending aorta in both RLAT and LLAT positions, varied considerably in size. The RLAT position best outlined structures to the left of midline, including the left auricle, interventricular sulcus, outflow region of the right ventricle, and the origin of the pulmonary artery. The LLAT position best demonstrated structures to the right of midline, including the right atrium, proximal part of the cranial and caudal vena cavae, and ascending aorta. The considerable range of normal variation between dogs in this study must be considered in the interpretation of clinical pneumopericardiograms.

Effect of vestibular deafferentation upon positional nystagmus in the squirrel monkey.

Seventeen of eighteen squirrel monkeys, under a restrained condition, showed positional nystagmus in different body positions. Good repeatability and consistency of the nystagmus were found, especially at the left-lateral, right-lateral, and head-hanging positions. Positional nystagmus was not observed after the subject underwent bilateral labyrinthectomy. However, one subject in which part of the crista ampullaris posterior remained, continuously showed a positional nystagmus. Therefore, the existence of a minimal vestibular imput from the crista ampullaris could provoke the nystagmus. Some changes occurred in positional nystagmus after bilateral macular ablation; however, the nystagmus did not completely disappear. Even though imput from the crista ampullaris is essential to provoke positional nystagmus in squirrel monkeys, the positional nystagmus probably results from a central dyscoordination between vestibulo-oculomotor function, spino-oculomotor function, vestibular and brain circulation, and psychological condition.