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The impact of focused transthoracic echocardiography in non-cardiac anaesthesia and surgery

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Canty, DJ (2012) The impact of focused transthoracic echocardiography in non-cardiac anaesthesia and surgery. PhD thesis, University of Tasmania.

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Abstract

Transthoracic echocardiography (TTE), usually performed by cardiologists, is increasingly used by physicians at the patient‟s bedside. Focused TTE is an abbreviated study used as part of clinical assessment to improve diagnostic accuracy and aid clinical decision-making in real-time. Cardiac disease is a leading cause of perioperative mortality, which may be contributed to by poor preoperative cardiac assessment. The hypothesis is that focused TTE influences cardiovascular diagnosis and management by anaesthetists.
An audit of focused TTE revealed changes to anaesthetist‟s management plans in 53% of 87 patients undergoing emergency surgery (75%), elective surgery (56%) and preoperative assessment clinic assessment (22%). TTE helped guide preoperative cardiology referral, anaesthetic technique, invasive monitoring and postoperative disposition. TTE was possible in 10 out of 24 patients with intraoperative haemodynamic instability, avoiding need for transoesophageal echocardiography and associated risk of oesophageal injury.
I conducted prospective observational studies of 100 patients attending the preoperative assessment clinic for elective surgery; and 99 patients requiring emergency surgery. In patients with clinically suspected cardiac disease or age ≥65 years, the anaesthetist‟s management plan was compared before and after TTE performed by an independent anaesthetist.
In elective surgery, the TTE findings triaged patients to those with significant cardiac pathology leading to a step-up in care (20%), and those without, leading to a step-down in care (34%). Management was also altered in asymptomatic patients aged over 65 years (step-up in 10%, step-down in 15%). An overall reduction in hospital resource use (cardiology referral, invasive monitoring and intensive care) and improved efficiency (less delays and hospital visits) resulted.
In emergency surgery, TTE revealed significant cardiac pathology in 75%, altering preoperative assessment in 67% leading to a higher step-up (36%) than step-down (8%) in treatment. Haemodynamic treatment changes (such as fluids and invasive monitoring) were more common (30%) than changes to surgical workflow and postoperative intensive care (14%).
In a retrospective cohort sub-analysis, the mortality of 64 hip fracture patients who received preoperative TTE was compared to a randomised retrospective control group with similar risk factors. Mortality was lower in the TTE group over the 30 days (4.7% v 15.2%, p=0.047) and 12 months after surgery (17.1% versus 33.3%, p=0.031). Hazard of death over 12 months was reduced after adjustment for known risk factors (hazard ratio 0.41, 95% CI 0.2 to 0.85, p=0.016).
In surgical patients at increased risk of cardiac disease, preoperative focused TTE by anaesthetists frequently changed management decisions and may reduce mortality.

Item Type: Thesis (PhD)
Keywords: echocardiograph, anesthesiology, peri operative medicine
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Date Deposited: 21 Jan 2013 06:45
Last Modified: 11 Mar 2016 05:52
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