Considerations
Prior to performing TAVI considerable assessment and planning is required by the anaesthetic team and cardiologists with pre-, peri-, and post-operative phases to consider. Firstly, prophylactic antibiotics should be discussed between the teams and a suitable choice shown be given whilst checking for allergies and ensuring renal and liver function are stable and appropriate for the given antibiotic dose. If GA is chosen; invasive monitoring such as an arterial line and CVC should be used, which can come with complications such as internal carotid artery cannulation, pneumothorax, bleeding, infection though this is minimised due to ultrasound guidance and operator experience. Choice of anaesthetic agents for induction is dependent of the anaesthetists familiarly and experience of the drugs; typically, propofol, midazolam, fentanyl, ketamine can all be used during induction. These agents have a multitude of side effects such as respiratory depression, bradycardia, and haemodynamic collapse resulting in the need for vasopressors. Neuromuscular blockade is required in these cases and come with their own set of side effects such as rocuronium which has been favourable for rapid sequence induction and has been known to cause anaphylaxis. Advantages of GA however are multiple: definite airway control, patient compliance, easier management of haemodynamic challenges as well as ventilating patients who cannot remain supine for long periods such as those with sleep apnoea. [2]
Bispectral index (BIS) is a useful measure of the depth of anaesthesia, in conjunction with the patient’s clinical status and external factors such as drugs, temperature, volume status can be used to assess the depth of anaesthesia. BIS provide a numerical value which and can help balance the quantity of anaesthetic agents to reach a certain depth of sedation and haemodynamic stability. He et al performed a study looking into the effectiveness of BIS in patients with sedation. In the sedation group low doses of dexmetomidine, propofol, and remifentanyl were infusion targeting a BIS range of 60-70 with addition boluses of propofol or fentanyl to decrease BIS to 40-60 during operator activity such as skin incision. Of 117 patients 77 had BIS monitoring for TAVI under sedation and LA. The GA group and Sedation group has similar patients’ characteristics. Total procedure time was less in the sedation group, with less blood loss and less catecholamine use. Rate of complications such as ventricular fibrillation and cardiac tamponade was similar between groups. 2 patients were converted to GA. 30-day mortality was similar between groups and length of hospital stay was longer in the GA group. Post-operative nausea and vomiting were less in the sedation group, and the GA group has a higher rate of pulmonary infection and pleural effusion. [17]
A case may be made for sedation over GA in terms of cost effectiveness, with finance influencing decisions being made in modern medical institutions as long as patient safety is not compromised; Toppen et al studied the clinical and financial outcomes of patients undergoing TAVI using CS. 196 patients were included in the study with 147 having GA and 49 having CS. In hospital mortality was 1.5% with a trend towards lower mortality in the CS group. The frequency of major adverse events was similar between groups. CS patients had fewer ICU hours, hospital days, and for 30 day follow up had improvement quality of life questionnaire scores. 30-day readmission rates were not different between groups. Costs for the CS groups were lower in multiple categories, such as ICU cost, anaesthesia Cost, operating room recovery cost, pharmacy cost, room cost. [18] Ahmad et al performed a retrospective review 418 patients with 46.4% having CS. Patients having GA were likely to be older, have symptomatic heart failure and lower average pre-procedural haemoglobin. Patients receiving CS had shorted ICU and hospital stays. In terms of costs however there was no statistically significant difference between the groups, with average total, direct and indirect cost being slightly higher in the CS group. Though CS was cost effective in terms of pharmacy cost, room cost, supply, physical therapy and imaging. [19] Mosleh et al performed a propensity matched analysis comparing patients undergoing TAVI with either GA or CS with 154 patients each. There was no difference in in hospital safety outcomes, 30-day mortality, or 30-day stroke between groups. They found shorter procedural times, length of stay, ICU stay and lower direct costs in every departmental category. [20]