Fasting or Non-fasting Before Cardiac Catheterization (FORCE)

Nil by mouth (NBM) has been the standard of care for cardiac catheterization since its inception. The associated vomiting was common with the first generation of radiocontrast materials that were almost toxic, and with the use of general anaesthesia. Induction of anaesthesia depresses the cough and swallow reflex, thus increasing the risk of aspiration. This is also true for deep sedation. However, the practice has largely changed nowadays, with cardiac catheterization procedures being done under local anaesthesia with anxiolytic sedatives often used peri-procedurally to achieve minimal sedation whereby verbal contact is maintained. Both the Royal College of Anaesthetists and the Royal College of Emergency Medicine state that fasting is not required for minimal or conscious sedation but does recommend fasting for general anaesthesia. There is only less than a 1% risk of needing emergency surgery for percutaneous coronary interventions (PCIs). The risk of developing pulmonary aspiration following emergency coronary artery bypass grafting (CABG) surgery or emergency direct current conversion (DC) in patients without pre-procedural fasting is in the order of 0.001%.

There was no evidence that the volume or pH of participants' gastric contents differ significantly between fasting and non-fasting populations, as shown by Brady et al. In addition, the overall incidence of nausea and vomiting was reported to be 1% before elective cerebral angiography in a study carried out by Kwon et al. with no significant difference between fasting and non-fasting groups.

A recently conducted a retrospective analysis of registry data for 1916 percutaneous coronary intervention (PCI) patients over a 3-year period. None of the patients was kept nil by mouth (NBM) pre-procedure, and no patients required immediate endotracheal intubation, nor did any develop aspiration pneumonia intra or post procedurally. Thus, they concluded in their observational study that patients undergoing PCI do not need to have fasted before their procedures.

The American Society of Anaesthesia guidelines discuss this extensively and have concluded that there is no strong relation between fasting, gastric volume, or risk of aspiration. In any case, the patients at highest risk for nausea and vomiting are those who present with ST-elevation myocardial infarction (STEMI), who are not fasting anyway, and the need for emergency intubation/CABG remains rare in these patients.

Prolonged unnecessary fasting can often leave patients dissatisfied and add to the discomfort and anxiety of waiting for a procedure. Patients may also choose to miss their usual medications on the morning of the procedure due to restrictions advised with oral intake, increasing the risk of complications such as poorly controlled hypertension and the associated peri-procedural complications.

There is also evidence that patients often choose to fast longer than advised by healthcare professionals. The reasons for this include: misunderstanding by the patient that a longer period of fasting may be more protective, apprehension and loss of appetite before an invasive procedure or practical problems with timing of the procedure. Many patients undergo prolonged periods of fasting before a procedure. While this is not usually a problem for young fit patients, many of the patients do not fall into this category. Many are elderly with multiple co-morbidities and thus run the risk of hypoglycaemia and lethargy.

Further consideration has to be that of patient flow through the cardiac unit. If patients have to be NBM for a certain period before cardiac catheterization, then it reduces the ability to fill lists at short notice if patients need to be cancelled. On the other hand, if the investigators can demonstrate that this period of NBM is unnecessary, the investigators could maximize the catheter lab work as a resource.

Finally, and probably most importantly, the investigators feel that the overall patient experience will be improved if patients are allowed to eat up to the point of procedure, decreasing the number of hungry, disgruntled patients who complain to nurses.

Our pilot study of 50 patients (25 patients in each group) showed that non-fasting before cardiac catheterization is a safe and feasible approach that carries no additional risk compared to the standard practice of fasting. There was no difference in the primary composite endpoint for safety between the fasting and non-fasting group (one patient in the fasting group developed nausea/vomiting during the procedure and none in the non-fasting group; 4% vs 0, p=0.31). Compared to the fasting group, the non-fasting group had more diabetic patients (4% vs 24%, p=0.009), higher admission blood sugar (7±3 mmol/L vs 5±1 mmol/L, p=0.01), and shorter duration between the last meal and the procedure (110±85 min vs 433±158, p=009). There was no statistically significant difference between the two groups regarding the patient questionnaire results, patient satisfaction score, incidence of hypotension or chest infection within 30 days.

In summary, though growing observational evidence suggests no benefit to fasting, there is no conclusive evidence derived from a robustly randomised controlled trial to support or oppose the continued use of pre-procedural fasting before cardiac catheterisation. This proposed trial aims to add to this body of evidence and clarify guidelines and recommendations pertaining to fasting.