Intrasession Variability and Yield of Wireless pH-metry following Sedated and Unsedated Capsule Placement

Abstract

Purpose: Wireless pH-metry capsules can be placed during EGD with the patient sedated or orally without sedation. We evaluated the day-to-day variability in esophageal acid exposure time (AET) following sedated (Sed) and unsedated (UnSed) wireless pH capsule placement in GERD patients off antireflux therapy, and assessed the diagnostic yield between the first and second 24-hr recording periods in Sed compared with UnSed patients. Methods: Consecutive patients were studied over two continuous 24-hr periods while off acid suppression medications. The pH telemetry capsule was positioned orally 5-6 cm above the LES either UnSed without EGD or Sed during EGD. Data were evaluated using chi-square, Spearman's correlation coefficient, and two-way repeated measures ANOVAs controlling for gender, age, and BMI. Statistical significance was set at P < 0.05 and values are presented as Mean±SD. Results: Patients (n=964) were grouped according to placement method as UnSed (n=655, 66% F, 50±14 yrs, BMI 28.4±6.3 kg/m2) or Sed (n=309, 63% F, 48±18 yrs, BMI 27.0±6.4 kg/m2). Similar patterns of total fractional acid exposure time (AET) were found between groups over the 2 days. No significant group or group x day interaction was found. Moderate correlations were identified between the two 24-hr recording periods in the Sed (r=.59, P<0.001) and Unsed (r=.65, P<0.001) groups. The proportion of patients with abnormal pH studies was similar on Day 1 and Day 2 in the UnSed (59% v 58%) and in the Sed (57% v 53%) groups. Of all normal studies on Day 1, 27% were found to be abnormal on Day 2.Figure: Total percent acid exposure time between sedated and unsedated patients between Day 1 and Day 2.Conclusion: Total AET was similar regardless of the method of pH capsule placement (sedated with endoscopy or transorally without sedation). The diagnostic yield was significantly increased with 48 hours of recording, highlighting the fact that a significant number of patients may be miscategorized as having a normal pH study (up to 27%), if only 24 hours of monitoring is performed.