The effects of protamine overdose on coagulation parameters as measured by the thrombelastograph.

BACKGROUND AND OBJECTIVE: Protamine is routinely administered following cardiopulmonary bypass in order to neutralize the effects of heparin. An excess of protamine can contribute to coagulopathy, hence predisposing to bleeding with associated morbidity and mortality. Thromboelastography (TEG) is recognized as an invaluable bedside tool to detect coagulation parameters; however, the effects of protamine overdose on TEG parameters have not been fully established. METHODS: Forty-six patients undergoing cardiac surgery using cardiopulmonary bypass were recruited in the study. Following heparinization, the patient's blood heparin level was measured using Hepcon HMS. Incremental doses of protamine [at a protamine-to-Hepcon-derived heparin ratio (PHR) of 1:1, 2:1 and 3:1] were added to patients' blood samples in vitro and four TEG coagulation parameters, including R (time to clot initiation), K (clot kinetics), alpha (clot kinetics) and maximum amplitude (ultimate clot strength), were monitored. Statistical analysis was performed using NCSS software. RESULTS: Protamine caused dose-dependent worsening of coagulation parameters on TEG; K was significantly elevated, whereas alpha and maximum amplitude showed significant reduction (P < 0.001) compared with baseline at a PHR of 2:1 and 3:1, respectively. R was significantly prolonged compared with baseline (P < 0.001) at a PHR of 3:1. CONCLUSION: Protamine adversely affects clot initiation time, clot kinetics and platelet function in a dose-dependent manner, which can predispose to bleeding.

Does preoperative computed tomography reduce the risks associated with re-do cardiac surgery?

A best evidence topic was written according to the structured protocol. The question addressed was whether preoperative computed tomography (CT) scan reduces the risk associated with re-do cardiac surgery. A Medline search revealed 412 papers, of which seven were deemed relevant to the topic. We conclude that preoperative CT angiography using ECG-gated multi-detector scan enables excellent anatomical details of heart, aorta and previous grafts, and highlights high-risk cases due to adherent grafts or ventricle or aortic atherosclerosis. This allows for better risk stratification and change of surgical strategy to reduce the potential risk in patients coming for re-do cardiac surgery. According to published reports, high-risk CT-scan findings in these patients caused clinicians to cancel surgery in up to 13% of cases, while preventive surgical strategies including non-midline approach, peripheral vascular exposure or establishing cardiopulmonary bypass prior to re-sternotomy have been reported in over two-thirds of patients with significant reduction in the operative risk. The risk of damage to vital structures, including previous grafts, heart or larger vessels is generally reported fewer than 10%, with evidence of significantly lower incidence of intra-operative injuries in patients who had prior CT-scans compared to those who did not. Hence, adequate preoperative imaging using ECG-gated multi-slice CT is essential for optimum planning of re-do cardiac surgery.

Segmental mediolytic arteriopathy with post-transplant lymphoproliferative disorder of the lung: case report and review of the literature.

Segmental mediolytic arteriopathy (SMA) is an extremely rare condition of uncertain etiology causing degeneration of arterial media, intramural dissection or the rupture of aneurysms. It is recognized as a rare cause of fatal intra-abdominal bleeding. We report the first case of recurrent intra-abdominal bleeding secondary to SMA in a lung transplant patient, with a further complication of lymphoproliferative disease in the transplanted lung. We discuss the pathogenesis, clinical presentation, imaging characteristics and the complexities of management in this case.

Early experience with the Levitronix Centrimag device for extra-corporeal membrane oxygenation following lung transplantation.

Extra-corporeal membrane oxygenation (ECMO) is accepted as a salvage therapy to treat life-threatening complications following lung transplantation such as primary graft dysfunction, acute rejection or airway dehiscence. Levitronix Centrimag (Levitronix LLC, Waltham, MA) is a centrifugal pump that consists of a magnetically levitated bearing-less rotor designed to reduce blood friction. ECMO using the Levitronix Centrimag pump may be an ideal medium-term support for lung transplant recipients suffering these serious complications. We describe our early experience of using ECMO with Levitronix Centrimag device and the Hilite hollow fibre membrane oxygenator (Medos Hilite LT, Medos Medizintechnik AG) in three cases following lung transplantation. The device is technically easy to implant and manage with a low complication rate on minimal anticoagulation.

Alteration in transthoracic impedance following cardiac surgery.

INTRODUCTION: Haemodynamically significant ventricular tachyarrhythmias are a frequent complication in the immediate post-operative period after cardiac surgery. Successful cardioversion depends on delivery of sufficient current, which in turn is dependent on transthoracic impedance (TTI). However, it is uncertain if there is a change in TTI immediately following cardiac surgery using cardiopulmonary bypass (CPB). METHODS: TTI was measured on 40 patients undergoing first time isolated cardiac surgery using CPB. TTI was recorded at 30 kHz using Bodystat Multiscan 5000 equipment before operation (with and without a positive end-expiratory pressure (PEEP) of 5 cm of H(2)O) and then at 1, 4 and 24 h after the operation. Data was analyzed to determine the relationship between pre- and post-operative variables and TTI values. RESULTS: Mean pre-operative TTI was 54.5+/-10.55 ohms without PEEP and 61.8+/-15.4 ohms on a PEEP of 5 cm of H(2)O. TTI dropped significantly (p<0.001) after the operation to 47.2+/-10.6 ohms at 1 h, 42.6+/-10.2 ohms at 4 h and 41.8+/-10.4 ohms at 24 h. A positive correlation was noted between duration of operation and TTI change at 1 h (r=0.38; p=0.016). There was no significant correlation between the duration of bypass and change in TTI. CONCLUSION: TTI decreases by more than 30% in the immediate post-operative period following cardiac surgery. This state may favour defibrillation at lower energy levels.

Extracorporeal membrane oxygenator as a bridge to successful surgical repair of bronchopleural fistula following bilateral sequential lung transplantation: a case report and review of literature.

BACKGROUND: Lung transplantation (LTx) is widely accepted as a therapeutic option for end-stage respiratory failure in cystic fibrosis. However, airway complications remain a major cause of morbidity and mortality in these patients, serious airway complications like bronchopleural fistula (BPF) are rare, and their management is very difficult. CASE PRESENTATION: A 47-year-old man with end-stage respiratory failure due to cystic fibrosis underwent bilateral sequential lung transplantation. Severe post-operative bleeding occurred due to dense intrapleural adhesions of the native lungs. He was re-explored and packed leading to satisfactory haemostasis. He developed a bronchopleural fistula on the 14th post-operative day. The fistula was successfully repaired using pericardial and intercostal vascular flaps with veno-venous extracorporeal membrane oxygenator (VV-ECMO) support. Subsequently his recovery was uneventful. CONCLUSION: The combination of pedicled intercostal and pericardial flaps provide adequate vascular tissue for sealing a large BPF following LTx. Veno-venous ECMO allows a feasible bridge to recovery.

Clinical outcomes in coronary artery bypass graft surgery: comparison of off-pump and on-pump techniques.

BACKGROUND: A consecutive series of patients undergoing first-time coronary artery bypass graft (CABG) surgery were analyzed and the impact of off-pump surgery was evaluated. METHODS: From January 1, 2000 to December 31, 2000, 367 patients underwent isolated first-time CABG surgery. One hundred and twenty underwent off-pump CABG (Group A, 32.7%) and 247 underwent conventional on-pump CABG (Group B, 67.3%). Five patients were converted during operation and were included in Group A. The pre-operative characteristics, intra-operative details, and post-operative course were analyzed in the two groups. All patients were followed up between 11 and 23 months (median 18 months) after operation by telephone interviews or questionnaire survey. RESULTS: Early mortality was 2.1% (group A, 0.83%; group B, 2.83%), with the difference not being statistically significant. The incidence of post-op stroke (group A, 1.66%; group B, 3.66%), renal failure (group A, 2.5%; group B, 5.66%), and gastrointestinal complications (group A, 1.66%; group B, 1.21%) was likewise not significantly different in the two groups. However, the patients in group A had a statistically significant lower incidence of low cardiac-output (group A 13.3%; group B 29.5%; p = 0.002), atrial fibrillation (group A 11.66%; group B 30.36%; p<0.001), blood product transfusion (group A 39.66%; group B 89.87%; p<0.001), time on ventilator (group A, 5.96 hrs; group B, 10.31 hrs; p<0.001), and post-op hospital stay (group A, 7.79 days; group B, 9.81 days, p<0.001). Medium-term results (recurrence of angina, late mortality, cardiovascular events, and need for revascularization) were similar in the two groups. CONCLUSIONS: Off-pump CABG results in a decreased incidence of complications in the immediate post-op period with comparable results in the medium term.