Colonoscopy is a common investigation and requires bowel preparation to empty the bowel and allow visualisation of the mucosa.
This study will investigate whether patients are significantly dehydrated after taking bowel preparation solution to undergo colonoscopy. The previous work of our research group has demonstrated that hypotension is common during sedation for endoscopy and it is not prevented by IV fluid administration prior to colonoscopy.
In this study we will combine the Clear Sight® noninvasive cardiac output monitor with a limited transthoracic echocardiography assessment to objectively record the intravascular volume status of the study cohort. Patients’ intraprocedure responses to sedation along with post-operative recovery will be determined. Investigation of the fluid status of patients undergoing colonoscopy in this study will allow targeted intervention for the prevention or effective management of hypotension during colonoscopy and ultimately increasing the safety of sedation for endoscopy by anaesthetists.
Dr Megan Allen, Professor Kate Leslie, Royal Melbourne Hospital, Melbourne, Vic.
The project was awarded $A54,938 through the ANZCA research grants program in 2017.
Hypotension is a common problem during sedation for endoscopy, but whether this is due to dehydration (from fasting, bowel preparation, or both), or to the sedative medications, was unknown. This study planned to use advanced technology, heart ultrasound, and a specialised finger probe, to measure if patients were dehydrated before their procedures. Both were used in the same patients to determine the suitability of the easier finger probe method for future patients, when cardiac ultrasound is unavailable. A secondary aim was to investigate whether patients who were dehydrated before procedure were more likely to have intra-procedural hypotension, and any differences in their recovery.
Patients undergoing elective lower intestinal endoscopy were found to commonly be dehydrated before their procedure on cardiac ultrasound. The technologies used to assess dehydration were inconsistent, and use of the finger probe when cardiac ultrasound is unavailable could not be recommended. After sedation, blood pressure commonly became lower than at baseline, and this reached a clinically important level for a significant minority of patients. Dehydrated patients were more likely to have clinically important hypotension during their procedure. Strategies to reduce dehydration in colonoscopy patients and optimising hypotension prevention during their procedure are important future research targets.
This research found that there was no reliable, readily available technology to determine patient dehydration when cardiac ultrasound is unavailable. However, understanding the commonality of pre-procedural dehydration and significantly low intra-procedural blood pressure can prepare anaesthetists better care for patients. ANZCA recently updated pre-procedure fasting guidelines which may assist future patients. The research increased understanding of the patient experience and increased knowledge vital for preventing future patient harm.