External Abdominal Pressure Research Articles

Colonoscope length and procedure efficiency

OBJECTIVE: We set out to compare the success of colonoscopy using long and intermediate length standard adult instruments. METHODS: An intermediate length (133 cm working length) and long (168 cm) videocolonoscope were used on an alternate patient basis during routine endoscopy lists. Completion rates, times, and the need for external abdominal pressure were documented, as were causes of failed cecal intubation. RESULTS: Among patients with no history of colon resection and with satisfactory bowel preparation, 173 procedures were performed with the intermediate and 167 with the long colonoscope. There was no significant difference in completion rates (96% for both, excluding patients with strictures), completion times (intermediate mean = 7.73 min, long = 8.11 min; p = 0.44), or need for external abdominal pressure. Similarly, no difference was observed for male and female patients analyzed separately. Though there was no significant difference in completion rates for males and females overall (99% vs 95% excluding patients with strictures, p = 0.08), the latter had significantly longer completion times (mean = 8.75 vs 6.76 min, p < 0.001) and were more likely to require external abdominal pressure. Intermediate colonoscope length was responsible for failure to reach the cecum in one patient only (0.6%). CONCLUSIONS: Although the length of the intermediate instrument rarely compromises colonoscopy, it offers no significant advantage over the long scope for routine procedures.

Effect of a pelvic belt on abdominal pressure by various weights and bending angles.

Back support belts are one of the important measures for preventing low back pain. One theory attributes the effectiveness of such a belt to the intraabdominal pressure it applies. The purpose of this study was to investigate the effect of a pelvic belt on abdominal pressure when the subject held four different weights at four different bending angles. The subjects of the study were ten male students who did not suffer low back pain. They wore a cuff with a blood pressure meter on their abdomens under the pelvic belt. They held a weight for 5 s slightly above an adjustable stand at a specified forward bending angle. The external abdominal pressure (EAP) was measured 4 s after lifting the weight. The weight was 0, 10, 20 or 30 kg; the angle was 0, 30, 60 or 90 degrees; there were 4 x 4 = 16 trials/subject. As the weight increased (at all angles), EAP increased significantly. However, at 0 kg and 10 kg, EAP decreased as the angle increased; at 0 kg, EAP decreased significantly. Thus, the belt should be effective for manual material handling due to the sensitive response of EAP for low back load. With light weights such as 0 kg and 10 kg, it is better to use the belt at small bending angles than at large bending angles because EAP decreases as the angle increases.

Hemodynamic effects of intermittent pneumatic compression of the lower limbs during laparoscopic cholecystectomy

Background: The effects of surgical pneumoperitoneum on lower-limb venous hemodynamics have already been studied; however, the effects of intermittent compression boots are not known in such venous-stasis conditions. Methods: In 12 volunteers and 12 patients, the venous hemodynamic effects of intermittent leg compression were studied under external abdominal pressure or during laparoscopic cholecystectomy, respectively. Femoral venous diameter and velocity were measured. Venous pressure was monitored during the surgical procedures. Results: External abdominal pressure of 50 mm Hg and pneumoperitoneum were found to increase the diameter (17% in the volunteers and 14% in the patients) and decrease peak velocity (49% and 32%, respectively) in the femoral vein. Femoral pressure was increased (106%) during pneumoperitoneum. In both venous-stasis circumstances, intermittent compression of the legs restored venous flow velocity, but had no effect on vessel diameter and pressure. Conclusions: The lower-limb venous hemodynamic changes were similar during external abdominal pressure or pneumoperitoneum, and the flow velocity decrease was intermittently reversed by pneumatic compression boots.

Diaphragmatic plate electrode stimulation of the hamster diaphragm

We developed a new technique of diaphragmatic stimulation by apposing plate electrodes directly against the diaphragm (DPS) in adult Golden Syrian hamsters. The electrophysiological and the mechanical responses to DPS were compared with those with phrenic nerve stimulation. In four animals, evaluation of the electromyogram before and after curare demonstrated that plate electrode stimulation occurred via the phrenic nerve filaments. In four animals, similar transdiaphragmatic pressure was produced at maximal current with DPS and phrenic nerve stimulation. Using DPS increasing current beyond a certain level resulted in recruitment of muscles besides the diaphragm. In six animals, an external abdominal pressure of 15 cmH2O produced maximal transdiaphragmatic pressure, suggesting that the diaphragm was contracting near optimal position with this external abdominal pressure. In another four animals the twitch and pressure-frequency characteristics with the use of DPS were found to be reproducible over a 2-h period. We conclude that DPS is an effective method of diaphragmatic stimulation and should prove to be a valuable technique to study the diaphragm in long-term studies of small rodents.

409 RADIONUCLIDE TEST FOR GASTROESOPHAGEAL REFLUX (GER) IN CHILDREN

A simple and reliable means of detecting abnormal GER in children is needed. A radionuclide method was evaluated in a series of 25 patients with documented GER (positive pH reflux test). Symptomatic patients with abnormal pH reflux test (pH < 4.0) were studied. With the patient supine or semi-upright, 200 uci of TC-99m sulfur colloid in apple juice was given orally. Patients were allowed to drink until sated (volume 60-300cc). Gamma camera images were then made in the basal state, with hand pressure and at graded increments of external abdominal pressure (blood pressure cuff around abdomen) up to 100 mm Hg. Any visible activity in the esophagus was interpreted as an abnormal test. In addition, all patients had lower esophageal sphincter pressure (LESP) determinations as well as barium cine-gastroesophagograms. The radionuclide study was easy to perform and well tolerated. Evidence of reflux was detectable in 20 patients using this method. The LESP was 12 mm Hg or less in 14 patients. The barium x-ray study was abnormal in 15 patients. Radionuclide gastroesophagography is a sensitive technique for detecting GER in infants and children. Additional studies to further assess clinical utility and specificity appear warranted.