Aim: To differentiate between physiological and pathological left ven- tricular hypertrophy in at... more Aim: To differentiate between physiological and pathological left ven- tricular hypertrophy in athletes using echocardiography. Methods and results: Eleven patients with mild hypertrophic cardiomyopathy were compared against 17 international rowers with mild left ventricular hypertrophy, and 30 age matched controls. The time difference between peak Ea (Doppler tissue imaging) and peak mitral valve opening (using M-mode) was measured simulta- neously.
Background: Hemodilution and blood transfusion are associated with poor outcome after cardiac sur... more Background: Hemodilution and blood transfusion are associated with poor outcome after cardiac surgery. We hypothesized that routine norepinephrine infusion commenced prior to anesthesia induction during on-bypass cardiac surgery would reduce intraoperative hemodilution and red cell transfusion. Methods: Two cohorts of consecutive cardiac surgery patients at different time periods were retrospectively reviewed for perioperative hemoglobin, creatinine concentrations and units of red cells transfused. Patients in group NE (n=72, in 2010) all received standardized hemodynamic management by a single anesthesiologist with low dose norepinephrine infusion commenced at 3-5 μg.min-1 (18-30 nmol.min-1, 0.24-0.4 nmol.kg-1.min-1) commencing prior to anesthetic induction and continued into the postoperative period. In the absence of blood loss, hemodynamic stability was achieved using vasopressors and inotropes rather than fluid administration, in an attempt to reduce hemodilutional anemia and t...
Despite advances in medical care, hip fracture surgery remains one of the commonest and high risk... more Despite advances in medical care, hip fracture surgery remains one of the commonest and high risk surgical procedures (10% in-hospital mortality and 25% at one year), representing a major economic cost to our community and a World health care burden. Hip fracture patients are usually elderly and chronic cardiovascular disease is common. Due to urgency of surgery, frequent patient cognitive impairment and limitations in health care resources, cardiac disease is often inadequately treated and remains the leading cause of mortality. Preoperative transthoracic echocardiography performed in the echocardiography laboratory non invasively alerts treating physicians to cardiac disease but may result in a delay which is associated with worse outcome and hence has been restricted to selected patients. Anesthesiologists have been increasingly performing their own ‘goal-focused transthoracic echocardiography’, an abbreviated examination which really forms an extension of clinical examination, w...
Canadian journal of anaesthesia = Journal canadien d'anesthésie, 2014
Shock is defined as a situation where oxygen transport is inadequate to meet the body's oxyge... more Shock is defined as a situation where oxygen transport is inadequate to meet the body's oxygen demand. An understanding of the mechanism(s) of reduced cardiac output, a determinant of oxygen transport, is crucial in order to initiate appropriate therapy to manage shock. Combining the concept of venous return with the ventricular pressure-volume relationship is a useful method to appreciate the complex circulatory physiology of shock. Clues from the patient's history, physical examination, and key laboratory tests, along with the careful inspection of hemodynamic, electrocardiographic and respiratory waveforms can help with the identification of the etiology and mechanism(s) of shock. Following verification of the arterial pressure, general resuscitation can begin, and more specific treatment can be undertaken to manage shock. If the patient is unresponsive to these measures, bedside ultrasound can then be performed to ascertain more detail regarding the mechanism(s) and etio...
Ultrasound simulation allows students to virtually explore internal anatomy by producing accurate... more 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.
Left atrial pressure and its surrogate, pulmonary capillary wedge pressure (PCWP), are important ... more 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. 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). 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 c...
Intraoperative transoesophageal echocardiography is increasingly used for guiding intraoperative ... more 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. 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. 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). 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.
Aim: To differentiate between physiological and pathological left ven- tricular hypertrophy in at... more Aim: To differentiate between physiological and pathological left ven- tricular hypertrophy in athletes using echocardiography. Methods and results: Eleven patients with mild hypertrophic cardiomyopathy were compared against 17 international rowers with mild left ventricular hypertrophy, and 30 age matched controls. The time difference between peak Ea (Doppler tissue imaging) and peak mitral valve opening (using M-mode) was measured simulta- neously.
Background: Hemodilution and blood transfusion are associated with poor outcome after cardiac sur... more Background: Hemodilution and blood transfusion are associated with poor outcome after cardiac surgery. We hypothesized that routine norepinephrine infusion commenced prior to anesthesia induction during on-bypass cardiac surgery would reduce intraoperative hemodilution and red cell transfusion. Methods: Two cohorts of consecutive cardiac surgery patients at different time periods were retrospectively reviewed for perioperative hemoglobin, creatinine concentrations and units of red cells transfused. Patients in group NE (n=72, in 2010) all received standardized hemodynamic management by a single anesthesiologist with low dose norepinephrine infusion commenced at 3-5 μg.min-1 (18-30 nmol.min-1, 0.24-0.4 nmol.kg-1.min-1) commencing prior to anesthetic induction and continued into the postoperative period. In the absence of blood loss, hemodynamic stability was achieved using vasopressors and inotropes rather than fluid administration, in an attempt to reduce hemodilutional anemia and t...
Despite advances in medical care, hip fracture surgery remains one of the commonest and high risk... more Despite advances in medical care, hip fracture surgery remains one of the commonest and high risk surgical procedures (10% in-hospital mortality and 25% at one year), representing a major economic cost to our community and a World health care burden. Hip fracture patients are usually elderly and chronic cardiovascular disease is common. Due to urgency of surgery, frequent patient cognitive impairment and limitations in health care resources, cardiac disease is often inadequately treated and remains the leading cause of mortality. Preoperative transthoracic echocardiography performed in the echocardiography laboratory non invasively alerts treating physicians to cardiac disease but may result in a delay which is associated with worse outcome and hence has been restricted to selected patients. Anesthesiologists have been increasingly performing their own ‘goal-focused transthoracic echocardiography’, an abbreviated examination which really forms an extension of clinical examination, w...
Canadian journal of anaesthesia = Journal canadien d'anesthésie, 2014
Shock is defined as a situation where oxygen transport is inadequate to meet the body's oxyge... more Shock is defined as a situation where oxygen transport is inadequate to meet the body's oxygen demand. An understanding of the mechanism(s) of reduced cardiac output, a determinant of oxygen transport, is crucial in order to initiate appropriate therapy to manage shock. Combining the concept of venous return with the ventricular pressure-volume relationship is a useful method to appreciate the complex circulatory physiology of shock. Clues from the patient's history, physical examination, and key laboratory tests, along with the careful inspection of hemodynamic, electrocardiographic and respiratory waveforms can help with the identification of the etiology and mechanism(s) of shock. Following verification of the arterial pressure, general resuscitation can begin, and more specific treatment can be undertaken to manage shock. If the patient is unresponsive to these measures, bedside ultrasound can then be performed to ascertain more detail regarding the mechanism(s) and etio...
Ultrasound simulation allows students to virtually explore internal anatomy by producing accurate... more 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.
Left atrial pressure and its surrogate, pulmonary capillary wedge pressure (PCWP), are important ... more 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. 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). 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 c...
Intraoperative transoesophageal echocardiography is increasingly used for guiding intraoperative ... more 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. 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. 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). 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.
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