Objective assessment of technical skills in cardiac surgery.

OBJECTIVE: Reduced training time combined with no rigorous assessment for technical skills makes it difficult for trainees to monitor their competence. We have developed an objective bench-top assessment of technical skills at a level commensurate with a junior registrar in cardiac surgery. METHODS: Forty cardiothoracic surgeons were recruited for the study, consisting of 12 junior trainees (year 1-3), 15 senior trainees (year 4-6) and 13 consultants. The assessment consisted of four key tasks on standardised bench-top models: aortic root cannulation, vein-graft to aorta anastomosis, vein-graft to Left Anterior Descending (LAD) anastomosis and femoral triangle dissection. An expert surgeon was present at each station to provide passive assistance and rate performance on a validated global rating scale giving rise to a total possible score of 40. Three expert surgeons repeated the ratings retrospectively, using blinded video recordings. Data analysis employed non-parametric tests. RESULTS: Both live and video scores differentiated significantly between performances of all groups of surgeons for all four stations (P < 0.01) (median live and video score for LAD; Junior 19,17; Senior 29,22; Consultant 36,28). Correlations between live and blinded rating were high (r = 0.67-0.84; P < 0.001) as was inter-rater reliability between the three expert video raters (alpha = 0.81). CONCLUSIONS: The use of bench-top tasks to differentiate between cardiac surgeons of differing technical abilities has been validated for the first time. Furthermore, it is unnecessary to perform post-hoc video rating to obtain objective data. These measures can provide formative feedback for surgeons-in-training and lead to the development of a competency-based technical skills curriculum.     

Non-invasive measurements of cardiac output after cardiac surgery

Canadian Journal of Anesthesia/Journal canadien d'anesthésie -     

Transoesophageal echocardiography is unreliable for cardiac output assessment after cardiac surgery compared with thermodilution

This randomised, single-blind, double-control study compared and established prospectively the best transoesophageal echocardiography methods for determining cardiac output in patients after cardiac surgery. Thirty patients undergoing coronary artery bypass grafting were included. Measurements were taken postoperatively, after stabilisation in the intensive care unit. Cardiac output was determined by transoesophageal echocardiography in randomised order through the aortic, mitral, and pulmonary valves, right and left ventricular outflow tracts, transgastric surface areas of the left ventricle and left ventricle two-dimensional volumes (Simpson's rules). 'Eyeball guessing' was done off-line. The best results were transaortic measurements using the triangular shape assumption of valve opening, but some values deviated considerably, and none of these approaches reached the limit of agreement set at 30% when compared to thermodilution. Eyeball guessing was comparable to the best transoesophageal echocardiography measurements. We conclude that transoesophageal echocardiography is an unreliable tool for determination of cardiac output in intensive care after cardiac surgery.     

Exercise assessment in infants after cardiac transplantation

BACKGROUND: Few data describe exercise performance after cardiac transplantation during infancy. The aim of this study was to compare the cardiorespiratory response to exercise in healthy subjects with that of subjects who had undergone heart transplantation during infancy to treat hypoplastic left heart syndrome. METHODS: Subjects (24 heart transplant recipients and 25 healthy controls) exercised on a treadmill using pediatric ramp protocols. We measured heart rate (HR), blood pressure, and metabolic data. Median age at transplantation was 20 days (range, 4 to 97 days). Age of recipients at exercise testing was 9.7 +/- 2.3 years and in healthy subjects was 10.5 +/- 1.4 years (p=not significant [NS]). RESULTS: Exercise duration was similar in both groups (10.3 +/- 2.0 minutes in recipients vs 11.1 +/- 1.5 minutes in healthy subjects, (p=NS). Heart rate at rest was greater in recipients (94 +/- 15 beats per minute [bpm] vs 85 +/- 11 bpm, p=0.02). Peak HR also was less in the recipient group (158 +/- 15 bpm vs 189 +/- 12 bpm, p <0.001). Peak oxygen consumption was 14% less in the recipients (32.3 +/- 5.6 ml/kg/min vs 36.8 +/- 5.5 ml/kg/min, p <0.01). Ventilatory anaerobic threshold was decreased in recipients, 27.6 +/- 9.6 vs 32.8 +/- 6.0, p <0.05. Respiratory exchange ratio at peak exercise was equal in both groups (1.06 +/- 0.06 vs 1.06 +/- 0.08). Oxygen pulse index did not differ significantly, 5.5 +/- 1.1 ml/beat/m2 in recipients and 6.1 +/- 1.7 ml/beat/m2 in healthy subjects (p=NS). CONCLUSIONS: Overall, children who undergo cardiac transplantation in infancy have exercise capacities within the normal range. These recipients have a decreased heart rate reserve that may account for the differences in peak oxygen consumption when compared with healthy subjects.     

Comparison of continuous cardiac output measurements in patients after cardiac surgery

OBJECTIVE: To investigate in a direct comparison accuracy and precision of continuous cardiac output measurements assessed by continuous pulmonary artery thermodilution technique (TDCCO), continuous pulse contour analysis (PCCO), and noninvasive partial CO(2)-rebreathing technique (NICO) in patients after coronary artery bypass grafting (CABG) during the postoperative period. DESIGN: Prospective, controlled clinical study. SETTING: University hospital. PARTICIPANTS: Twenty-two patients undergoing elective CABG surgery. INTERVENTIONS: Hemodynamic measurements were performed after admission to the ICU and in sequence every 2 hours during the subsequent 6-hour period. Simultaneously, cardiac output (CO) was measured using a TDCCO, PCCO, and NICO. After the continuous cardiac output measurements were read, bolus thermodilution-derived cardiac output was obtained from thermodilution curves detected in the pulmonary artery (TDBCO(pa)). Four intermittent consecutive boli consisting of 10 mL of ice-cold saline were randomly injected over the ventilatory cycle. MEASUREMENTS AND MAIN RESULTS: The comparison between the continuous cardiac output measurement methods TDCCO versus PCCO showed a bias of -0.12 L/min, between TDCCO versus NICO -0.17 L/min, and between PCCO versus NICO -0.44 L/min. The comparison to the reference technique between TDBCO(pa) versus TDCCO revealed a bias of -0.28 L/min, between TDBCO(pa) versus PCCO -0.40 L/min, and between TDBCO(pa) versus NICO -0.64 L/min. CONCLUSIONS: The results of this clinical investigation show agreement between TDCCO and PCCO to satisfy clinical requirements in a setting of postoperative patients after cardiac surgery. In contrast, the NICO monitor is of very limited use in these patients.     

Delayed thoracic closure after cardiac surgery in infants

We report 4 cases of delayed thoracic closure after cardiac surgery in infants: 3 cases with transposition of the great arteries and one with hypoplastic left heart syndrome. Sternal and skin closure in the primary operation sometimes causes haemodynamic cardiac compression. Postoperative correction of haemodynamic and haemostatic functions are allowed by delayed sternal and skin closure. No complications were encountered.     

Management of low cardiac output syndrome after cardiac surgery using enoximone

This case report describes the use of enoximone, a potent phosphodiesterase F-IV inhibitor with inotropic and vasodilator actions, to treat low output syndrome after cardiac surgery. The reduced cardiac output was unresponsive to a combination of inotropic drugs and intra-aortic balloon counterpulsation was contraindicated. Cardiac output was increased dramatically by enoximone, but systemic vascular resistance and perfusion pressure remained low until the addition of metaraminol.     

Thermodilution cardiac output measurement in infants and small children following intracardiac surgery

A modified catheter has been used in conjunction with a thermodilution cardiac output computer for postoperative assessment of cardiac function in infants and children.Because of the small amount of fluid required for each determination and the simplicity of the technique, serial measurements can be done safely.Its use has a contributed to the early detection of low output states. It has also proven to be a useful tool for estimating the optimal heart rate in each patient and for assessing the effectiveness of therapeutic measures.     

Nosocomial infections in infants and children after cardiac surgery

Objective  To identify the incidence, characteristics and risk factors of nosocomial infections (NIs) in infants and children undergoing open heart surgery, a prospective observational study. Methods  One hundred consecutive infants and children < 2 yrs of age undergoing open heart surgery (OHS) between March 2007 and December 2007 were included in the study. Samples for blood, endotracheal and urine culture were drawn daily during intensive care unit (ICU) stay. Cultures from endotracheal tube, central venous catheter, arterial cannula, chest tube, urinary catheter and other invasive lines were also obtained. Centers for Disease Control and Prevention criteria were used for defining NIs. A number of possible risk factors predisposing to NI were analyzed. Results  32% patients developed NI. The NI rate was 49%. Common NIs were bloodstream infection (19%), respiratory tract infection (17%), catheter site infection (7%) and urinary tract infection (6%). Common pathogens were Acinetobacter (22.5%), Pseudomonas aeruginosa (20.4%), Klebsiella pneumoniae (16.3%) and Staphylococcus aureus (12.2%). Major risk factors for NI were length of ICU stay (p < 0.001), duration of intubation (p < 0.001), reintubation (p < 0.001), duration of central venous catheterization (p = 0.001), preoperative congestive heart failure (p = 0.002), tracheostomy (p = 0.003), duration of preoperative stay (p = 0.01), blood transfusion (p = 0.01), preoperative balloon atrial septostomy (p = 0.02), duration of surgery (p = 0.03), surgical complexity score (p = 0.03) and hypothermia (p = 0.03). The mortality rate was 11% with significant association between NI and death (p = 0.002). Conclusion  NIs develop frequently in infants and children after OHS. This study may serve as a reference point for further development and implementation of interventions aimed at reducing NI rates and improving patient outcome.     

Monitoring of cardiac output by thermodilution after open-heart surgery.

One hundred twenty-five separate cardiac output determinations were obtained after open-heart surgery in 10 patients by simultaneous use of thermodilution and dye-dilution techniques. Mean thermodilution cardiac output was 1.6 per cent greater than mean dye-dilution cardiac output (5.24 versus 5.16 L. per minute). Reproducibility of thermodilution cardiac output (coefficient of variation, 8.6 per cent) was superior to that of dye-dilution cardiac output (coefficient of variation, 12.3 per cent) for outputs ranging from 2.5 to 8.7 L. per minute (p less than 0.001). Linear regression analysis revealed a correlation showing that COtd = 0.86 COdye + 0.80 (r = 0.9, p less than 0.001) and indicating a similarity between thermodilution and dye-dilution output figures except in extremely low output states. In such cases, thermodilution cardiac output becomes progressively larger than dye-dilution cardiac output. The results indicate that thermodilution cardiac output is a valid method for determining cardiac output in the rapidly changing clinical setting following cardiopulmonary bypass. Clinical applications of this technique include evaluation of the efficacy of inotropic agents, effectiveness of intra-aortic balloon counterpulsation, and status of the low output syndrome postoperatively. Routine use in patients with Class III or IV cardiac disease appears justified.     

外源性肺泡表面活性物质在婴儿心脏直视术后的应用

目的　评价外源性肺泡表面活性物质 ( PS)治疗婴儿体外循环后肺损伤的疗效。　方法　选择 7例术后反复撤机失败 ,依赖机械通气 ,胸部 X线片显示大片肺不张和 /或肺间质透亮度降低的婴儿 (年龄 0 .4 9± 0 .82岁 ,体重 4 .87± 2 .18kg) ,在至少 1次撤机失败后经气管内插管应用 PS,初始量按 10 0 mg/kg给药 ,12小时后重复 1次。分别在初始量后 4、6、12、2 4、4 8和 72小时测定氧合指数 ( OI)、动脉血氧饱和度 ( Sa O2 )和动脉血二氧化碳分压 ( Pa CO2 ) ,记录自主呼吸潮气量、胸部 X线片变化以及呼吸机应用时间。　结果　 PS使用 4小时后 OI、Sa O2 显著升高 ,2 4小时后增幅最大 ,分别为给药前的 34.7%和 6 .6 % ;Pa CO2 在给药 4小时后显著降低 ,6小时后最大降幅为 2 2 .8% ( P<0 .0 5 ,0 .0 1)。用药后患者最大自主呼吸潮气量、胸部 X线片明显改善 ,拔管成功率 85 .7%。　结论　外源性 PS替代治疗能显著改善婴儿心脏直视术后肺功能 ,并有效缩短机械通气时间     

Heart rate and cardiac output after atropine in anaesthetised infants and children

Purpose

Heart rate is considered to be a major determinant of cardiac output in infants and small children but the relationships between age, heart, rate and cardiac output in humans have never been clearly established. This study was designed to determine the change in cardiac output following atropine iv to anaesthetised infants and small children. Methods: Following-,Institutional Ethics Committee approval and written-informed consent, 20 ASA l or ll unpremeditated patients aged from 1 to 36 mo were studied. Anaesthesia was induced with 5 mg · kg^?1 thiopentone, 2 μg · kg^?1 fentanyl and maintained with halothane 0.5% in nitrous oxide 66% in oxygen. Vecuronium, 0.1 mg · kg^?1 was used to provide muscular relaxation. Cardiac output was measured by non-invasive transthoracic blind continuous-wave Doppler echocardiography before and after the administration of 0.02 mg·kg^?1 atropine iv.

Resulits

Atropine increased both heart rate and cardiac index by 31.1 ± 12.8% and 29.4 ± 17.3% respectively (P < 0.05). The cardiac index before atropine was 5.1 ± 1.2 L.min^?1m^?2 and the increase after atropine varied widely from 1,4 to 52.1%. Although atropine did not alter the overall stroke index the recorded changes ranged from -20.8 to + 18.0%. There was no association between age and either cardiac index or % change in cardiac index after atropine. However, there was a positive but weak correlation between percentage change in heart rate and cardiac output (r²=0.46).

Conclusion

Atropine causes a variable increase in cardiac output in infants and children aged between 1 and 36 mo. The change in cardiac,output, considering the limits of the transthoracic echocardiography methodology, suggests that this is related to the increase in heart rate but is not dependent of age.     

Safety of ketorolac in neonates and infants after cardiac surgery

BACKGROUND: Ketorolac is an injectable nonsteroidal anti-inflammatory drug that is often used as a transitional short-term analgesic to treat moderate pain and to decrease opioid use. There is a paucity of literature documenting the safety of using ketorolac in neonates and infants after cardiac surgery. METHODS: A retrospective chart review was performed which identified all patients <6 months of age who received ketorolac after cardiac surgery. Patients' demographic, surgical, and dosing data were collected. A Student's t-test was used to identify significant differences in renal and hematologic laboratory values at baseline and at 48 h of treatment. RESULTS: A total of 53 children <6 months of age received at least one dose of ketorolac after cardiac surgery. Eleven of 53 children (21%) were <1 month of age. The blood urea nitrogen/serum creatinine (SCr) levels increased from baseline at 48 h of therapy in all infants, but stayed within normal limits. The largest increase in SCr level from baseline on any day of ketorolac therapy was 26 micromol x l(-1) (0.3 mg x dl(-1)) which occurred in two neonates. Four patients (three infants and one neonate) had minor episodes of bleeding while being treated with ketorolac. There were no clinically significant changes in hemoglobin, hematocrit or platelet count. None of these episodes caused hemodynamic instability nor required transfusion of blood products. CONCLUSIONS: Ketorolac was used safely in neonates and infants who have had cardiac surgery at our institution. Ketorolac was not associated with any adverse hematologic or renal effects. Prospective investigation is warranted to further assess the safety and effectiveness of ketorolac in this patient population.     

Measurement of cardiac output after cardiac surgery by a new transesophageal Doppler device

OBJECTIVES: Assessment of hemodynamics by transesophageal Doppler devices (TDD) may be a less invasive alternative to the pulmonary artery catheter. In contrast to the TDD evaluated so far, a new monitor (HemoSonic100) measures both blood flow velocity and the diameter of the descending aorta. The aim of this study was to assess the accuracy of the cardiac output/index (CO/CI) measured by this device compared with the CO/CI measured by thermodilution. DESIGN: Prospective nonrandomized study. SETTING: Community hospital; university-based statistician. PARTICIPANTS: Twenty-two patients. INTERVENTIONS: Elective coronary artery bypass grafting and/or valve replacement/repair. MEASUREMENTS AND MAIN RESULTS: After routine cardiac surgery, CO/CI was determined in the intensive care unit by iced-water bolus (IWB), continuous cardiac index (CCI) assessment, and the TDD. Matched measurements were made with each patient at intervals of 30 minutes. Six percent of sets were incomplete because of failed signal detection by the TDD. Bland-Altman analysis revealed a mean bias of 0.23 L/min/m(2) for TDD and IWB. Mean bias for CCI and IWB was 0.11 L/min/m(2). The correlation between TDD and IWB (r(2) = 0.09) for cardiac index was found to be inferior to the correlation between CCI and IWB (r(2) = 0.65). Trend analysis between sequential measurements (T1-4: dTDD, dCCI, dIWB) showed a lower correlation between dTDD and dIWB (r(2) = 0.1) compared with the correlation between dCCI and dIWB (r(2) = 0.44). CONCLUSION: The transesophageal Doppler device (HemoSonic100) cannot be recommended as a sole method for monitoring cardiac output in patients after cardiac surgery.     

Postoperative intensive care in infants and children after cardiac surgery

Background The postoperative course of infants and children after open heart surgery is often complicated by cardiopulmonary insufficiency or low cardiac output. Methods From January 1989 to April 1992 441 infants and children with congenital heart disease underwent cardiac surgery. 128 of these patients (29%) required prolonged or extensive intensive care because of cardiopulmonary insufficiency or low cardiac output. Aortic cross clamp and cardiopulmonary bypass times were measured in all patients. In the postoperative period duration of mechanical ventilation, duration of intensive care, special monitoring and therapeutic strategies and clinical scores were documented. Results The overall mortality rate was 9.9%, the mortality rate in patients with postoperative cardiopulmonary insufficiency or low cardiac output was 34%. The mortality rate increased significantly up to 73% when the cardiopulmonary bypass time exceeded 200 min. Mean duration of intensive care of survivors (S) and nonsurvivors (NS) was 10.3±0.8 and 4.1±1.2 days, respectively (p<0.01), mean duration of mechanical ventilation was 7.1±0.5 (S) and 4.1±1.2 (NS) days, respectively (p<0.01). NS had a significantly higher degree of physiologic derangement assessed by the Acute Physiologic Score for Children and needed more monitoring and therapeutic interventions assessed by the Therapeutic Intervention Scoring System than S. Conclusion Complex cardiac surgery, a cardiopulmonary bypass time over 200 min, high catecholamine infusion rates combined with a persisting low mean arterial pressure are associated with a high postoperative mortality rate in infants and children with congenital heart defects.     

Comparison of enoximone versus tobutamine in the treatment of low cardiac output after cardiac surgery

Enoximone, a new cardiotonic agent not related to glycosides or catecholamines, has been suggested for treatment of low cardiac output syndromes occurring after cardiopulmonary bypass (CPB). The aim of the present study was to compare enoximone with dobutamine in the management of such cases. Twenty consecutive patients who had undergone cardiac surgery with CPB and who had a cardiac index (CI) less than 2.5 l.min-1.m-2, pulmonary capillary wedge pressure greater than 12 mmHg, and no renal failure, were randomly assigned to receive either enoximone (group E, n = 10) or dobutamine (group D, n = 10). The following parameters were monitored at baseline, 15, 30, 60, 90 min, 2, 6, 10 and 14 h: arterial, central venous, pulmonary arterial and capillary wedge pressures (PCWP), cardiac index (CI), stroke volume index (SVI), stroke work index (SWI), systemic (SVR) and pulmonary vascular resistances, as well as heart rate-pressure product (HRPP). Patients in group E were given a bolus of 0.5-1 mg.kg-1 enoximone over a 20 min period, followed by a continuous infusion of 2-20 micrograms.kg-1.min-1, depending on clinical response. In group D, patients were given 2.5 to 15 micrograms.kg-1.min-1 dobutamine according to clinical response. No other inotropic drug was used during the study period. The aim was to obtain an increase in CI greater than or equal to 30% at the end of the first hour of treatment. Excessive systemic hypotension with low SVR was treated with volume loading.(ABSTRACT TRUNCATED AT 250 WORDS)