Observation of Unique Practices: Metoclopramide Prior to Aortic Cannulation and ‘AUTO-agitating’ Diluted Propofol for Contrast Echocardiography
Year: 2024
Type: article
Abstract: The authors as anaesthesiologists have seen different ways in anaesthesia practice first in training then in practice in developing world before training again and then practicing again in developed world. As observed by one of the authors, one such unique practice that is unheard of and thus undocumented in medical literature is the use of metoclopramide as a self-limiting ‘normotensive’ during cardiac surgery.[1,2] Metoclopramide use has been limited to anti-emesis and pro-kinesis, so it has been an eye-opener to the observant author to see its alternative use for transient self-limiting ‘normotension’ just before aortic cannulation during cardiac surgery. The skeptic author raised the irrelevance of using metoclopramide when one can get away with small doses of nitroglycerine which is titratable and universally used unlike metoclopramide. The observant author has the same concern but in the absence of any untoward incidents observed at the institution using it religiously for more than few years, the observant author is not as skeptical as the skeptic author. The bottom-line is to explore how this practice came into existence and whether this practice can be emulated at other institutions unless the known side effects of metoclopramide especially in elderly patients who are more likely to undergo cardiac surgeries preclude its use becoming popular in the face of unknown long-term beneficial effects if any when it is used just prior to aortic cannulation. Similarly, in case of unavailability of cost-prohibitive intravascular contrast agents during echocardiography to rule out intra-cardiac and intra-pulmonary shunts, the observant author has observed the practice of agitated and diluted propofol admixed with normal saline in 1:9 ratios as similar to off-label admixing with 5% albumin in 3:7 ratios[3,4] unlike admixing with 5% dextrose in 1:4 ratios per manufacturer’s recommendations.[5] However, agitation may not be warranted with oil-water micro-interfaces during dilution of oil-based propofol with water-based normal saline/5% dextrose themselves lasting long enough when diluting immediately before administration into peripheral venous access site to appear as contrast in cardiac chambers during echocardiography under sedation-anaesthesia. It is not clear whether manufacturer’s recommendations to not go below dilution of 2 mg/ml propofol (admixed with 5% dextrose in 1:4 ratios) are to limit micro/macro-bubbles developing within diluted propofol (due to oil-water interface) or within veins due to diluted propofol (due to oil-water-blood interface). Moreover, for sake of sustained contrast remaining visible for sufficient time in cardiac chambers, it is not clear with off-label use of diluted propofol whether lower volume of 5 ml in 1:4 ratios (2 mg/ml) will be as good as usual volume of 10 ml in 1:9 ratios (1 mg/ml) unless higher volume of 20 ml in 1:19 ratios (0.5 mg/ml) may be better though may not be safer as way more dilute than manufacturer’s recommendations of 2 mg/ml. The same application may be possible with lipid emulsion too, but lipid emulsion’s additional cost may be unnecessary considering that propofol is always handy when almost all bubble studies are primarily performed during trans-oesophageal studies which usually have anaesthesia personnel already administering propofol for sedation-anaesthesia. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.
Source: NMO journal
Authors: Amit Jain, Deepak Gupta
Institutions: Ascension, Detroit Medical Center
Language: English
Subfield: Anesthesiology and Pain Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: diamond
OpenAlex ID: W4405372610