David Canty

Audit of anaesthetist-performed echocardiography on perioperative management decisions for non-cardiac surgery

BACKGROUND Intraoperative transoesophageal echocardiography is increasingly used for guiding intraoperative management decisions during non-cardiac surgery. Transthoracic echocardiography (TTE) equipment and training is becoming more available to anaesthetists, and its point-of-care application may facilitate real-time haemodynamic management and preoperative screening. METHODS We conducted an audit of transthoracic and transoesophageal echocardiograms, performed by an anaesthetist at a tertiary referral centre over a 9-month period, to identify the effect of echocardiography on clinical decision-making in patients undergoing non-cardiac surgery. The indications for echocardiography followed published guidelines. RESULTS Echocardiographic examinations of 97 patients included 87 transthoracic, and 14 transoesophageal studies. Of 36 studies conducted in the preoperative clinic, eight revealed significant cardiac pathology, necessitating cardiology referral or admission before surgery. Preoperative transthoracic echocardiograms performed on the day of surgery (n=39) led to two cancellations of surgery owing to end-stage cardiac disease, the institution of two unplanned surgical procedures (drainage of pleural and pericardial effusions), and to significant changes in anaesthetic and haemodynamic management, or both in 18 patients. Greater influence on management occurred with emergency surgery (75%) than elective surgery (43%). Intraoperative transthoracic (n=10) and transoesophageal (n=14) echocardiography also altered management (altered surgery in two patients, cancellation in one, and altered haemodynamic management in 18 patients). CONCLUSIONS Anaesthetist-performed point-of-care TTE and thoracic ultrasound may have a high clinical impact on the perioperative management of patients scheduled for non-cardiac surgery.

The impact of focused transthoracic echocardiography in the pre‐operative clinic

Patients with suspected or symptomatic cardiac disease, associated with increased peri‐operative risk, are often seen by anaesthetists in the pre‐assessment clinic. The use of transthoracic echocardiography in this setting has not been reported. This prospective observational study investigated the effect of echocardiography on the anaesthetic management plan in 100 patients who were older than 65 years or had suspected cardiac disease. Echocardiography was performed by an anaesthetist, and was validated by a cardiologist. Overall, the anaesthetic plan was changed in 54 patients. Haemodynamically significant cardiac disease was revealed in 31 patients, resulting in a step‐up of treatment in 20 patients, including: cardiology referral (four patients); altered surgical (two) and anaesthetic (four) technique; use of invasive monitoring (13); planned use of vasopressor infusion (10); and postoperative high dependency care (five). Reassuring negative findings in 69 patients led to a step‐down in treatment in 34 patients: altered anaesthetic technique (six); procedure not cancelled (10); cardiology referral not made (10); use of invasive monitoring not required (seven); and high dependency care not booked (11). We conclude that focused transthoracic echocardiography in the pre‐operative clinic is feasible and frequently alters management in patients with suspected cardiac disease.

The impact of pre-operative focused transthoracic echocardiography in emergency non-cardiac surgery patients with known or risk of cardiac disease

This prospective observational study investigated the effect of focused transthoracic echocardiography in 99 patients who had suspected cardiac disease or were ≥ 65 years old, and were scheduled for emergency non‐cardiac surgery. The treating anaesthetist completed a diagnosis and management plan before and after transthoracic echocardiography, which was performed by an independent operator. Clinical examination rated cardiac disease present in 75%; the remainder were asymptomatic. The cardiac diagnosis was changed in 67% and the management plan in 44% of patients after echocardiography. Cardiac disease was identified by echocardiography in 64% of patients, which led to a step‐up of treatment in 36% (4% delay for cardiology referral, 2% altered surgery, 4% intensive care and 26% intra‐operative haemodynamic management changes). Absence of cardiac disease in 36% resulted in a step‐down of treatment in 8% (no referral 3%, intensive care 1% or haemodynamic treatment 4%). Pre‐operative focused transthoracic echocardiography in patients admitted for emergency surgery and with known cardiac disease or suspected to be at risk of cardiac disease frequently alters diagnosis and management.

The impact on cardiac diagnosis and mortality of focused transthoracic echocardiography in hip fracture surgery patients with increased risk of cardiac disease: a retrospective cohort study

Hip fracture surgery is associated with a high rate of mortality and morbidity; heart disease is the leading cause and is often unrecognised and inadequately treated. Pre‐operative focused transthoracic echocardiography by anaesthetists frequently influences management, but mortality outcome studies have not been performed to date. Mortality over the 12 months after hip fracture surgery, in 64 patients at risk of cardiac disease who received pre‐operative echocardiography, was compared with 66 randomised historical controls who did not receive echocardiography. Mortality was lower in the group that received echocardiography over the 30 days (4.7% vs 15.2%, log rank p = 0.047) and 12 months after surgery (17.1% vs 33.3%, log rank p = 0.031). Hazard of death was also reduced with pre‐operative echocardiography over 12 months after adjustment for known risk factors (hazard ratio 0.41, 95% CI 0.2–0.85, p = 0.016). Pre‐operative echocardiography was not associated with a delay in surgery. These data support a randomised controlled trial to confirm these findings.

Focused echocardiography: a systematic review of diagnostic and clinical decision-making in anaesthesia and critical care

Focused echocardiography is becoming a widely used tool to aid clinical assessment by anaesthetists and critical care physicians. At the present time, most physicians are not yet trained in focused echocardiography or believe that it may result in adverse outcomes by delaying, or otherwise interfering with, time‐critical patient management. We performed a systematic review of electronic databases on the topic of focused echocardiography in anaesthesia and critical care. We found 18 full text articles, which consistently reported that focused echocardiography may be used to identify or exclude previously unrecognised or suspected cardiac abnormalities, resulting in frequent important changes to patient management. However, most of the articles were observational studies with inherent design flaws. Thirteen prospective studies, including two that measured patient outcome, were supportive of focused echocardiography, whereas five retrospective cohort studies, including three outcome studies, did not support focused echocardiography. There is an urgent requirement for randomised controlled trials.

Interatrial septum motion but not Doppler assessment predicts elevated pulmonary capillary wedge pressure in patients undergoing cardiac surgery.

Background:Left atrial pressure and its surrogate, pulmonary capillary wedge pressure (PCWP), are important for determining diastolic function. The role of transthoracic echocardiography (TTE) in assessing diastolic function is well established in awake subjects. The objective was to assess the accuracy of predicting PCWP by TTE and transesophageal echocardiography (TEE) during coronary artery surgery. Methods:In 27 adult patients undergoing on-pump coronary artery surgery, simultaneous echocardiographic and hemodynamic measurements were obtained immediately before anesthesia (TTE), after anesthesia and mechanical ventilation (TTE and TEE), during conduit harvest (TEE), and after separation from cardiopulmonary bypass (TEE). Results:Twenty patients had an ejection fraction (EF) of 0.5 or greater. With the exception of E/e′ and S/D ratios, echocardiographic values changed over the echocardiographic studies. In patients with low EF, E velocity, deceleration time, pulmonary vein D, S/D, and E/e′ ratios correlated well with PCWP before anesthesia. After induction of anesthesia using TTE or TEE, correlations were poor. In normal EF patients, correlations were poor for both TEE and TTE at all five stages. The sensitivity and specificity of echocardiographic values were not high enough to predict raised PCWP except for a fixed curve pattern of interatrial septum (area under the curve 0.89 for PCWP ≥17, and 0.98 for ≥18 mmHg) and S/D less than 1 (area under the curve 0.74 for PCWP ≥17, and 0.78 for ≥18 mmHg). Conclusion:Doppler assessment of PCWP was neither sensitive nor specific enough to be clinically useful in anesthetized patients with mechanical ventilation. The fixed curve pattern of the interatrial septum was the best predictor of raised PCWP.

Repeated Monitoring With Transthoracic Echocardiography and Lung Ultrasound After Cardiac Surgery: Feasibility and Impact on Diagnosis

OBJECTIVES Cardiorespiratory complications are common after cardiac surgery and current monitors used to diagnose these are invasive and have limitations. Transthoracic echocardiography and lung ultrasound are noninvasive and frequently improve diagnosis in critically ill patients but have not been reported for routine postoperative monitoring after coronary, valve, and aortic surgery. The aim was to determine whether both repeated postoperative transthoracic echocardiography and lung ultrasound revealed or excluded clinically important cardiac and respiratory disorders compared to conventional monitoring and chest x-ray. DESIGN Prospective observational study. SETTING Tertiary university hospital. PARTICIPANTS Ninety-one patients aged older than 18 undergoing cardiac surgery INTERVENTIONS Postoperative clinical patient assessment for significant cardiac and respiratory disorders by the treating physician was recorded at 3 time points (day after surgery, after extubation and removal of chest drains and at discharge) using conventional monitoring and chest x-ray. After each assessment, transthoracic echocardiography and lung ultrasound were performed, and differences in diagnosis from conventional assessment were recorded. MEASUREMENTS AND MAIN RESULTS Transthoracic echocardiography was interpretable in at least 1 echocardiographic window in 99% of examinations. Transthoracic echocardiography and/or lung ultrasound changed the diagnosis of important cardiac and/or respiratory disorders in 61 patients (67%). New cardiac findings included cardiac dysfunction (38 patients), pericardial effusion (5), mitral regurgitation (2), and hypovolemia (1). New respiratory findings included pleural effusion (30), pneumothorax (4), alveolar interstitial syndrome (3) and consolidation (1). CONCLUSIONS Routine repeated monitoring with cardiac and lung ultrasound after cardiac surgery is feasible and frequently alters diagnosis of clinically important cardiac and respiratory pathology.

Ultrasound simulator‐assisted teaching of cardiac anatomy to preclinical anatomy students: A pilot randomized trial of a three‐hour learning exposure

Ultrasound simulation allows students to virtually explore internal anatomy by producing accurate, moving, color, three‐dimensional rendered slices from any angle or approach leaving the organs and their relationships intact without requirement for consumables. The aim was to determine the feasibility and efficacy of self‐directed learning of cardiac anatomy with an ultrasound simulator compared to cadavers and plastic models. After a single cardiac anatomy lecture, fifty university anatomy students participated in a three‐hour supervised self‐directed learning exposure in groups of five, randomized to an ultrasound simulator or human cadaveric specimens and plastic models. Pre‐ and post‐tests were conducted using pictorial and non‐pictorial multiple‐choice questions (MCQs). Simulator students completed a survey on their experience. Four simulator and seven cadaver group students did not attend after randomization. Simulator use in groups of five students was feasible and feedback from participants was very positive. Baseline test scores were similar (P = 0.9) between groups. After the learning intervention, there was no difference between groups in change in total test score (P = 0.37), whether they were pictorial (P = 0.6) or non‐pictorial (P = 0.21). In both groups there was an increase in total test scores (simulator +19.8 ±12.4%% and cadaver: +16.4% ± 10.2, P < 0.0001), pictorial question scores (+22.9 ±18.0%, 19.7 ±19.3%, P < 0.001) and non‐pictorial question scores (+16.7 ±18.2%, +13 ±15.4%, P = 0.002). The ultrasound simulator appears equivalent to human cadaveric prosections for learning cardiac anatomy. Anat Sci Educ 8: 21–30.

A pilot assessment of 3 point-of-care strategies for diagnosis of perioperative lung pathology.

BACKGROUND: Lung ultrasonography is superior to clinical examination and chest X-ray (CXR) in diagnosis of acute respiratory pathology in the emergency and critical care setting and after cardiothoracic surgery in intensive care. Lung ultrasound may be useful before cardiothoracic surgery and after discharge from intensive care, but the proportion of significant respiratory pathology in this setting is unknown and may be too low to justify its routine use. The aim of this study was to determine the proportion of clinically significant respiratory pathology detectable with CXR, clinical examination, and lung ultrasound in patients on the ward before and after cardiothoracic surgery. METHODS: In this prospective observational study, patients undergoing elective cardiothoracic surgery who received a CXR as part of standard care preoperatively or after discharge from the intensive care unit received a standardized clinical assessment and then a lung ultrasound examination within 24 hours of the CXR by 2 clinicians. The incidence of collapse/atelectasis, consolidation, alveolar-interstitial syndrome, pleural effusion, and pneumothorax were compared between clinical examination, CXR, and lung ultrasound (reference method) based on predefined diagnostic criteria in 3 zones of each lung. RESULTS: In 78 participants included, presence of any pathology was detected in 56% of the cohort by lung ultrasound; 24% preoperatively and 94% postoperatively. With lung ultrasound as a reference, the sensitivity of the 5 different pathologies ranged from 7% to 69% (CXR), 7% to 76% (clinical examination), and 14% to 94% (combined); the specificity of the 5 different pathologies ranged from 91% to 98% (CXR), from 90% to 99% (clinical examination), and from 82% to 97% (combined). For clinical examination and lung ultrasound, intraobserver agreements beyond chance ranged from 0.28 to 0.70 and from 0.84 to 0.97, respectively. The agreements beyond chance of pathologic diagnoses between modalities ranged from 0.11 to 0.64 (CXR and lung ultrasound), from 0.08 to 0.7 (CXR and lung ultrasound), and from 0 to 0.58 (clinical examination and CXR). CONCLUSIONS: Clinically important respiratory pathology is detectable by lung ultrasound in a substantial number of noncritically ill, pre or postoperative cardiothoracic surgery participants with high estimate of interobserver agreement beyond that expected by chance, and we showed clinically significant diagnoses may be missed by the contemporary practice of clinical examination and CXR.

High frequency jet ventilation through a supraglottic airway device: a case series of patients undergoing extra‐corporeal shock wave lithotripsy

High frequency jet ventilation has been shown to be beneficial during extra‐corporeal shock wave lithotripsy as it reduces urinary calculus movement which increases lithotripsy efficiency with better utilisation of shockwave energy and less patient exposure to tissue trauma. In all reports, sub‐glottic high frequency jet ventilation was delivered through a tracheal tube or a jet catheter requiring paralysis and direct laryngoscopy. In this study, a simple method using supraglottic jet ventilation through a laryngeal mask attached to a circle absorber anaesthetic breathing system is described. The technique avoids the need for dense neuromuscular blockade for laryngoscopy and the potential complications associated with sub‐glottic instrumentation and sub‐glottic jet ventilation. The technique was successfully employed in a series of patients undergoing lithotripsy under general anaesthesia as an outpatient procedure.