The impact of continuous haemofiltration with high-volume fluid exchange during cardiopulmonary bypass surgery on the recovery of patients with impaired renal function: a pilot randomised trial.

BACKGROUND: There is widespread variability in clinical practice within cardiac surgery units worldwide on the use of haemofiltration. The clinical impact and safety of this modality is, however, unknown. OBJECTIVES: The primary pilot trial objectives were as follows: to assess the feasibility of randomising 60 patients with impaired kidney function undergoing on-pump coronary artery bypass graft (CABG) surgery within 6 months; to assess the suitability and reliability of our chosen outcome measures; to explore issues that may impact on recruitment into a definitive trial; and to undertake an exploratory economic evaluation. DESIGN: A pilot, single-centre, open-label randomised trial. SETTING: Liverpool Heart and Chest Hospital NHS Foundation Trust between November 2010 and March 2012. PARTICIPANTS: Men and women, aged > 18 years of age, undergoing on-pump CABG surgery, who had pre-operative impaired kidney function indicated by an estimated glomerular filtration rate (eGFR) of < 60 ml/minute adjusted for 1.73 m(2) of body surface area. INTERVENTIONS: Group 1: patients who received haemofiltration during bypass (experimental group). Group 2: patients who did not receive haemofiltration during bypass (control group). MAIN OUTCOME MEASURES: (1) Feasibility outcome measures: barriers to recruitment to a larger trial were documented as observations made during the recruitment period of the trial. Reliability of data collection methods was monitored using a 13-point case record form validation check for data entry against the patient clinical notes and the trial database. (2) The main clinical outcomes were frequency of intensive care unit (ICU) stay of duration > 3 days and the length of ICU stay days. (3) Other clinical outcomes were the need for postoperative haemofiltration in the ICU, mechanical ventilation time, hospital stay, composite of outcome of unfavourable perioperative events and eGFR values at 6 weeks' follow-up. (4) Secondary health economic feasibility outcomes. RESULTS: Recruitment into the pilot trial was from 21 November 2010 to 30 March 2012. Thirty-seven eligible patients were consented and successfully randomised into the trial arms (30%). The main issues impacting on recruitment were the high volume of off-pump CABG surgery within the centre; recruitment being restricted to research nurses' working hours of the week; issues arising associated with the screening process for identifying prospective eligible patients based on eGFR values; protocol deviations/treatment crossovers; and unexpected outbreaks of pandemic influenza and other infectious conditions. The data collection process was sufficiently robust, with few errors detected. The length of ICU stay days was deemed a suitable primary outcome. There was an overall trend towards reduction in the length of ICU stay for patients who were given intraoperative haemofiltration, more so for those with diabetes. The economic evaluation estimated that the incremental costs per person were £1744 lower for the intraoperative haemofiltration group, while the incremental benefits per person increased by 0.11. CONCLUSION: Given sufficient resources and broadening of the inclusion criteria, the recruitment into a larger multicentre trial is feasible and may demonstrate potential clinical and cost benefits of using intraoperative haemofiltration in this group of patients. However, owing to the small sample size in this pilot trial, no firm conclusions can be drawn from the findings at this stage. The outcomes of this pilot study are very encouraging and suggest that it is feasible to design a continuous superiority trial with the length of ICU stay days or time to tracheal extubation as the primary outcome measure, provided that guidelines for avoiding bias are implemented. An alternative primary outcome measure that avoids bias is mortality. The inclusion criteria should also be widened to include all cardiac surgery patients with impaired renal function. TRIAL REGISTRATION: ISRCTN49513454. FUNDING: This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 17, No. 49. See the HTA programme website for further project information.

Mechanism of development of aortic transection: a possible new angle.

Aortic transection injury is a frequently fatal injury secondary to sudden deceleration. To date magnitude of deceleration is the only factor known to influence the development of an aortic transection injury. We hypothesise that different 3D geometries of the aortic arch in healthy young adult patients as a possible predisposing factor for transection injuries when undergoing sudden deceleration. We extend this to hypothesise that the direction of deceleration may be important as well. In addition we hypothesise that the stage in the cardiac cycle, which determines central aortic blood pressure, when the deceleration occurs as an important factor. We utilise known engineering principles such as Newton's second Law of motion, moment of inertia, law of Laplace, and the theory of superposition to explain our hypothesis. We present limited data to demonstrate the wide variation in aortic arch 3D geometry to explain the possible an individual's variable susceptibility to transection injuries via the principle of moment of inertia. Engineering principles suggest that 3D aortic arch geometry, direction of deceleration and stage in the cardiac cycle, in addition to the magnitude of deceleration are potentially important factors in predisposing certain individuals in a given situation to aortic transaction injuries.

Open and closed chest extrathoracic cannulation for cardiopulmonary bypass and extracorporeal life support: methods, indications, and outcomes.

Extrathoracic cannulation to establish cardiopulmonary bypass has been widely applied in recent years and includes: (a) repeat surgery, (b) minimally invasive surgery, and (c) cases with diseased vessels such as porcelain, aneurysmal, and dissecting aorta. In addition, the success and relative ease of peripheral cannulation, among other technological advances, has permitted the development of closed chest extracorporeal life support, in the form of cardiopulmonary support and extracorporeal membrane oxygenation. With this development have come applications for cardiopulmonary bypass based support outside the traditional cardiac theatre setting, including emergency circulatory support for patients in cardiogenic shock and respiratory support for patients with severely impaired gas exchange. This review summarises the approach to extrathoracic cannulation for the generalist.

Effect of training on patient outcomes following lobectomy.

BACKGROUND: Little is known about the effect of surgical training on outcomes in thoracic surgery. The impact of surgeon training on outcomes following lung resection was examined, focusing on lobectomy as a marker operation. METHODS: 328 consecutive patients who underwent lobectomy at our institution between 1 October 2001 and 30 June 2003 were studied. Data were collected prospectively during the patient's admission as part of routine clinical practice and validated by a designated audit officer. Patient characteristics and postoperative outcomes were compared between trainee led and consultant led operations. RESULTS: In 115 cases (35.1%) the operation was performed by a trainee thoracic surgeon as the first operator. There were no significant differences in patient characteristics between the two groups. In-hospital mortality was similar for operations led by trainees and consultants (3.5% and 2.8%, respectively; p > 0.99). Outcomes in the two groups did not differ significantly with respect to respiratory, cardiovascular, renal, neurological, chest infection, bleeding, and gastrointestinal complications. Survival rates at 1 year were 82.6% for procedures led by trainees compared with 81.7% for procedures led by consultants (p = 0.83). CONCLUSIONS: With appropriate supervision, trainee thoracic surgeons can perform lobectomies safely without compromising short or intermediate term patient outcome.

Early discharge following coronary bypass surgery: is it safe?

OBJECTIVES: Early discharge has been proposed as a means of containing the escalating cost of health care in cardiac surgery. The aim of this study was to investigate whether shortening the length of hospital stay after coronary artery bypass surgery is safe and cost effective. METHODS: Patients (n=198) undergoing elective bypass surgery by two surgeons for a period of 12 months were prospectively entered into the study but not randomized. The anaesthetic and surgical treatments were identical in all patients with the exception that one of the surgeons used intermittent cold crystalloid cardioplegia ('normal discharge' group; n=119) and the other used intermittent ischaemia without cardioplegia ('early discharge' group; n=79). Previous to the study both surgeons discharged patients on the 7th-8th postoperative day. For the present study, one of the two surgeons adopted the new policy of discharging patients on the 4th postoperative day ('early discharge' group). The criteria for hospital discharge included: presence of sinus rhythm, absence of pyrexia and wound infection, normal routine blood tests, satisfactory chest X-ray and ECG and full mobility. RESULTS: The clinical characteristics were identical in the two groups. The number of grafts per patient was 2.8+/-0.8 and 3.2+/-1.0, and the total ischaemic time 47+/-13 and 46+/-14 min in the normal and early discharge groups, respectively (P=NS in each instance). In the normal discharge group the mean hospital stay was 7.7+/-3.3 days whereas in the early discharge group it was 4.7+/-2.0 days (P<0. 0001) with 73.5% of the patients being discharged within the first 4 days following surgery. The shortening of hospital stay resulted in a mean reduction of costs of pound750/patient. There was no operative mortality (<30 days following surgery) and the incidence of non-fatal perioperative complications were similar in the two groups, with the exception that the incidence of supraventricular arrhythmias was significantly higher in the normal discharge group than in the early discharge group (33% vs. 6.3% respectively; P<0. 0001). These rhythm abnormalities occurred within the first 4 days in 89% of patients following surgery and were the cause of readmission in only one patient in the normal discharge group. There were a total of ten (8.4%) readmissions in the normal discharge group and three (3.8%) in the early discharge group. CONCLUSION: Shortening the postoperative hospital stay to 4 days following elective coronary bypass surgery appears to be safe and can be a means of reducing the cost of care. This in turn may result in a greater availability of resources and in an effective way of reducing waiting lists.

Topical aprotinin in cardiac operations.

We performed a prospective, randomized, double-blind trial of topical aprotinin versus placebo in 100 patients undergoing cardiac operations with cardiopulmonary bypass. Fifty-five patients received aprotinin. Forty underwent coronary artery bypass grafting (CABG) and 15 valve replacement +/- CABG. Of 45 patients in the control group 38 underwent CABG and 7 valve replacement +/- CABG. Aprotinin (50 mL; 70 mg) or placebo was applied topically to the heart, pericardium, and mediastinum before sternal closure. There were five reentries for bleeding with a surgical site identified in four. Mean blood loss was significantly less in the aprotinin group (653 versus 903 mL; p = 0.002), and fewer aprotinin patients received blood as a volume expander (67.5% versus 88%; p = 0.03). In coronary patients alone when aspirin administration was continued until the day of operation there was no difference between treatment and placebo groups (768 versus 879 mL). When aspirin administration was discontinued 2 weeks before operation there was a significant difference (558 versus 884 mL; p = 0.016) as in the group overall. This provides the potential for intrapericardial instillation for patients with excessive postoperative bleeding.

Conduction velocities of corticospinal axons in the rat studied by recording cortical antidromic responses.

The rat corticospinal tract was stimulated at the medullary pyramid and at different levels in the spinal cord (segments C2/3, T2, T12) and responses were recorded from the surface of the cerebral cortex and extracellularly from individual cortical neurones. Irrespective of the site stimulated, the earliest surface and single unit responses had frequency-following and other characteristics which indicated they resulted from antidromic invasion of corticospinal neurones. Synaptically mediated discharges with longer latency were also evoked in cortical neurones other than corticospinal neurones. At least in part these discharges probably resulted from stimulus spread to the dorsal column-medial lemniscus pathway. Corticospinal neurones were almost all between 1.0 and 1.5 mm beneath the cortical surface while synaptically excited units were at all depths greater than 0.4 mm. By stimulating at two sites, estimates of conduction velocity were obtained for single corticospinal axons. For those reaching at least as far as T12, velocities caudal to the pyramid ranged from 5 to 19 m/s (mean 11.4 +/- 2.9 m/s; S.D.). Slow axons in the pyramid (antidromic latency greater than 2.5 ms) could rarely be excited from T12. By stimulating at three sites (pyramid, T2, T12) most axons reaching T12 were found to have similar conduction velocities in the 'cervical' (pyramid-T2) and 'thoracic' (T2-T12) cord. However, in 15% of the axons the 'thoracic' velocity was at least 25% less than the cervical. The results are discussed and related to those from previous investigations.