Fluid prescription practices of anesthesiologists managing patients undergoing elective colonoscopy: an observational study

Abstract

BackgroundRoutine fluid prescription is common practice amongst anesthesiologists caring for patients undergoing colonoscopy. However there is limited information about routine procedural fluid prescription practices of anesthesiologists in this setting. Routine fluid administration may also have important pharmaco-economic implications for the health care budget. Therefore we performed a prospective observational study assessing the fluid prescription practices of anesthesiologists caring for patients undergoing elective colonoscopy.MethodsWith Institutional Review Board approval, adult patients receiving procedural fluid intervention during elective colonoscopy were included. Data collected: size of intravenous cannula inserted, volumes of fluid administered, adverse events, procedure duration, and pharmaco-economic costs associated with fluid prescription. Anesthesiologists and gastroenterologists were blinded to the study.ResultsWe collected data on 289 patients who received fluid prescription by their attending anesthesiologist. Median patient age: 48 yrs (range 18–83), gender: 174 (60%) female; median duration of procedure: 24 minutes (range 12–48). Cannula size: 181 (63%) patients received a 22G cannula or smaller. Median volume of fluid administered during the colonoscopy was 325 ml (range 0 to 1000 ml). Median duration of the procedure: 25 minutes (range 12 to 48 minutes). Median volume of fluid administered in the post anaesthesia recovery unit: 450 ml (range 0 to 1000 ml). Fifteen patients (5%) became hypotensive during the procedure and two patients (<1%) developed hypotension in the PACU. There was no difference in the median fluid requirements between patients with hypotension and those without. Fluid volumes were strongly associated with increasing cannula diameter (p = 0.0001), however there was no association between fluid volumes administered and vasopressor use, peri-procedural adverse events, or procedure duration. At our institution fluid therapy currently cost about AUD$4.90 per patient: 1 L crystalloid $1.18 and fluid delivery set $3.77 Our institution performs over 9000 endoscopic procedures annually with fluid therapy costing about $45,000/year.ConclusionsRoutine fluid prescription by anesthesiologists managing patients undergoing colonoscopy was ineffective with low actual fluid volumes delivered during the procedure. There was no association between volumes of fluid delivered and procedural hypotension, adverse events, or procedure duration. Anesthesiologists should question the clinical and pharmaco-economic value of routine fluid administration for patients undergoing elective endoscopy.

A randomized-controlled trial of high- or low-volume intravenous Plasma-Lyte® to prevent hypotension during sedation for colonoscopy

“…1 Patients in our two studies were similar in terms of baseline characteristics, bowel preparation, and fasting, but the patients in our current study had longer procedures, received more propofol per minute, and had a higher incidence of hypotension than patients in our previous study. Our results are also consistent with Weinberg et al's observational study, 5 although the median volume of fluid infused in that study was only 325 (range 0-1,000) mL. There are a number of potential explanations for our results.…”

“…2 In an attempt to ameliorate these symptoms and signs, many anesthesiologists commonly administer prophylactic intravenous fluids during sedation for colonoscopy. 3,4 Nevertheless, this practice is not supported by the currently available evidence 1,5 and may increase the cost of care.…”

“…This explanation seems unlikely as 20 mLÁkg -1 is greater than or equal to volumes that have proved effective in clinical studies on fluid resuscitation in ambulatory surgery patients. [16][17][18] Our high-volume infusion was greater than is routinely administered clinically 5 and is at the upper end of volumes that are practical in an ambulatory setting. Third, the low-volume infusion, which was designed to improve blinding, may have been as effective as the high-volume infusion in preventing hypotension.…”

“…1 The primary outcome of that study (i.e., a C 25% decrease in systolic blood pressure [SBP] from baseline before fluid administration during sedation), the incidence of SBP \ 100 mmHg, and all other secondary outcomes were similar in the two groups. There is a lack of further randomized trials, although an observational study 5 did report no association between the volume of fluid administered and hypotension during the procedure. Nevertheless, 64% of anesthesiologists who responded to a recent survey still routinely administer prophylactic intravenous fluids.…”

The cardiovascular effects of crystalloid administration in endoscopy patients

“…2 Anaesthesiologists administer fluid in 64% of these cases with large variability in the volume given, despite there being no high quality data to support or refute this practice. 3,4 Neither high (20 ml/kg) nor low (2 ml/kg) volume crystalloid infusion reliably reduced the incidence of hypotension, which occurred in almost 60% of patients. 1 Similarly, high or low volume crystalloid administration does not clearly reduce more subjective symptoms such as nausea, vomiting, headache and light-headedness.…”