Abdominal ultrasound after colonoscopy with insufflation of carbon dioxide versus air

The Effect of Patient Oral Intake Status on Abdominal Aortic Ultrasound Visualization

BACKGROUND

The standard abdominal aortic duplex ultrasound protocol requires fasting for 8-12 hours prior to examination in attempt to reduce bowel gas and improve visualization. Such practice results in frequent testing delays and patient non-compliance. The aim of this study was to determine whether fasting improves visualization of the abdominal aorta in patients undergoing duplex ultrasound or influences diagnostic properties.

METHODS

This was a prospective, randomized, double-blind imaging trail at a single institution. Ninety patients were randomized to one of three dietary groups, including NPO, clear liquids or control (regular diet). Diagnostic ultrasound examinations were performed by accredited Registered Vascular Technologists who remained blinded to the patients' diet. Sonographers commented on the presence of limited visualization in the study based on their ability to accurately measure aortic diameter. Examination results were randomly assigned to interpreting physicians who were also blinded to the patients' diet. Following interpretation, the reading physician was asked to comment whether they had sufficient information for a conclusive diagnostic interpretation.

RESULTS

All ultrasound studies were deemed diagnostic by the interpreting physician regardless of the patients' dietary status. Limited visualization was reported in 19 of the 90 study patients (21.1%) with no significant difference existing between the dietary groups (P = 0.344). The NPO group contained the most patients with studies deemed to have limited visualization.

CONCLUSION

Oral intake status did not affect visualization of the abdominal aorta or the rate of diagnostic studies in patients undergoing DUS at a single center. These results suggest that dietary restrictions prior to DUS evaluation of the abdominal aorta is unnecessary.

Carbon dioxide insufflation for colonoscopy: evaluation of gas volume, abdominal pain, examination time and transcutaneous partial CO2 pressure

BACKGROUND

Insufflation with carbon dioxide (CO(2)) in colonoscopy has not been widely adopted and, consequently, limited data are available on insufflated gas volume and blood pCO(2). The aim of this study was to compare CO(2) and air as an insufflation agent in patients undergoing colonoscopy without sedation in terms of insufflated gas volume, pCO(2), pain and examination time.

METHODS

This was a randomized, double-blind, control trial. Consecutive patients presenting for colonoscopy, excluding those with lung or malignant disease, were randomized into two groups: insufflation with air or with CO(2), respectively. Insufflated gas volume, pain, pCO(2) and examination time were assessed.

RESULTS

The study cohort comprised 120 patients (66 randomized to CO(2) group). No significant difference in insufflated gas volumes was found between the CO(2) and air groups. The mean pCO(2) measured before, during (the peak value) and 30 min after colonoscopy were 40, 43 and 40 mmHg, respectively, in both groups. The pain scores in the air group were significantly greater than those in the CO(2) group until 3 h after the examination. There was a significant faster cecal intubation time and a trend toward shorter examination time in the CO(2) group.

CONCLUSIONS

The CO(2) gas volume used in our study (14.0 L) was much greater than that reported by others (8.3 L), but the pCO(2) values were still within the normal reference range, indicating the safety of CO(2) insufflation over a greater range of CO(2) gas volume. Among our patients, CO(2) insufflation was associated with relatively less pain and a shorter examination time. Based on our results, we recommend that CO(2) become the standard gas for insufflation in patients undergoing colonoscopy without sedation.