Knut S. Andersen

Rewarming from accidental hypothermia by extracorporeal circulation. A retrospective study

OBJECTIVE Twenty-six patients with accidental hypothermia combined with circulatory arrest or severe circulatory failure were rewarmed to normothermia by use of extracorporeal circulation (ECC). The aim of the present study was to evaluate our results. PATIENTS AND METHODS The treatment of six female and 20 male patients (median age: 26.7 years; range 1.9--76.3 years) rewarmed in the period 1987--2000 was evaluated retrospectively. Hypothermia was related to immersion/submersion in cold water (n=17), avalanche (n=1) or prolonged exposure to cold surroundings (n=8). Prior to admission, the trachea was intubated and cardiopulmonary resuscitation (CPR) initiated in all patients with cardiorespiratory arrest (n=22), whereas in those with respiration/circulation (n=4) only oxygen therapy via a face mask was given. RESULTS Nineteen of the 26 patients were weaned off ECC whereas seven died because of refractory respiratory and/or cardiac failure. Eight of the 19 successfully weaned patients were discharged from hospital after a median of 10 days. One patient died 3 days after circulatory arrest (complete atrioventricular block) resulting in severe cerebral injury. The remaining ten patients died following 1--2 days due to severe hypoxic brain injury (n=5), cerebral bleeding (n=1) or irreversible cardiopulmonary insufficiency (n=4). Based on the reports from the site of accident, two groups of patients were identified: the asphyxia group (n=15) (submersions (n=14); avalanche accident (n=1)) and the non-asphyxia group (n=11) (patients immersed or exposed to cold environment). Seven intact survivors discharged from hospital belonged to the non-asphyxia group whereas one with a severe neurological deficit was identified within the asphyxia group. CONCLUSION Patients with non-asphyxiated deep accidental hypothermia have a reasonable prognosis and should be rewarmed before further therapeutic decisions are made. In contrast, drowned patients with secondary hypothermia have a very poor prognosis. The treatment protocol under such conditions should be the subject for further discussion.

Surgical treatment of spontaneous pneumothorax by wedge resection without pleurodesis or pleurectomy

OBJECTIVE Evaluation of wedge resection of the lung without pleurodesis or pleurectomy as a method of surgical treatment for spontaneous pneumothorax in terms of complications, recurrence rate and postoperative complaints. METHODS Retrospective study of 132 operations for spontaneous pneumothorax in 120 patients (84 men and 36 women: mean age 34 years, range 14-77) performed between 1974 and 1993. The mean observation time was 84 months (range 6-229) and a 100% follow-up rate of all survivors (97%) was achieved. RESULTS The indications for surgery were recurrent pneumothorax (52%), persisting air leak during first episode (45%), or hemothorax (3%). Perioperative findings were single bullous disease (86%), 2-3 bullae (6%), diffuse bullous disease (5%) and no bullous disease in 3% of the cases. The overall complication rate was 16% (30-day mortality 1%, reoperation for postoperative bleeding 2%, bronchopneumonia 8%, new pneumothorax during hospital stay 5%). The late recurrence rate (operated lung) was 5%. All recurrences were successfully treated by drainage (n = 3), exsufflation (n = 1) or observation only (n = 3). Reoperation was not necessary. Thirty-seven percent of the patients had postoperative complaints which they associated with the operation. CONCLUSION Lung resection without pleurodesis or pleurectomy is a simple, safe and effective method of the surgical treatment of spontaneous pneumothorax in terms of complications and recurrence rate in patients with limited bullous disease.

Comparison of the centrifugal and roller pump in elective coronary artery bypass surgery—a prospective, randomized study with special emphasis upon platelet activation

Objective—Evaluation of the centrifugal pump vs roller pump concerning effects upon platelet function, hemolysis and clinical outcome in elective coronary artery bypass surgery. Design—Thirty‐four patients were randomized to centrifugal or roller pump. Platelet activation was studied by flow cytometry before, during and up to 3 days after bypass. Results—Duration of bypass, ischemic period, peripheral anastomoses, hospital stay and mortality did not differ. In roller pump patients, platelet aggregates increased by 250% between end of bypass and 3 h postoperatively (p < 0.001). A secondary, fivefold increase in number of platelet aggregates was found on the 3rd postoperative day (p < 0.001). In the centrifugal pump group, these changes were not significant. Hemolysis increased (20%) at end of bypass and 3 h postoperatively (p < 0.005), and decreased to preoperative levels the next day without group difference. Conclusion—Platelet aggregation was significantly increased in roller compared with centrifugal pump patients, indicating higher susceptibility to postoperative thrombotic complications with the roller pump. Otherwise, there was no clinical evidence for superiority of the centrifugal pump.

Dilation of the internal mammary artery by external papaverine application to the pedicle--an improved method.

Spasm of the internal mammary artery (IMA) during coronary bypass grafting may cause inadequate graft flow and makes accurate placement of sutures difficult. In addition, IMAs with poor intraoperative flow rates are more likely to occlude. In this study three methods for spasm prevention were compared in 51 patients undergoing coronary bypass surgery. In group 1, IMA pedicles were covered with a sponge soaked with papaverine solution (0.8 mg/ml of papaverine in 0.9% saline) and left intact distally, thus allowing continuous blood flow until used for bypass. In group 2, the IMAs were divided and clamped distally and the pedicle tucked into a papaverine-soaked sponge. In group 3, the IMAs were also divided distally, clamped, and placed under the upper sternum submerged in papaverine solution (0.8 mg/ml) inside a surgical glove. Free flow from the IMA was higher in group 3 than in groups 1 and 2 (60 ml/min vs. 44 and 30, respectively, P < 0.03). Morphometric measurements disclosed a larger luminal area and less folding of the internal elastic lamina in group 3 compared with groups 1 and 2 (0.73 mm2 vs 0.33 and 0.37, respectively, P < 0.03). Submersion in papaverine solution thus provides better procurement of IMA grafts than storage of the pedicle in a papaverine-soaked sponge.

Intraaortic counterpulsation during cardiopulmonary bypass impairs distal organ perfusion.

BACKGROUND Recent studies have focused on the use of fixed-rate intraaortic balloon pumping (IABP) during cardiopulmonary bypass (CPB) to achieve pulsatile flow. Because application of an IABP catheter may represent a functional obstruction within the descending aorta, we explored the effect of IABP-pulsed CPB-perfusion with special attention to perfusion above and below the IABP balloon. METHODS Sixteen animals received an IABP catheter that remained turned off position (NP group, n = 8) or was switched to an automatic mode of 80 beats/min during CPB (PP group, n = 8). Flow-data and pressure-data were obtained above and below the IABP balloon. Tissue perfusion was evaluated by microspheres. RESULTS IABP-pulsed CPB-perfusion, as assessed at 30 minutes on CPB, increased proximal mean aortic pressure (p < 0.05) and carotid artery blood flow (p < 0.001), but decreased distal mean aortic pressure (p < 0.001). The decrease of distal mean aortic pressure in the PP group was associated with a 75 % decrease (p < 0.001) of renal tissue perfusion. During nonpulsed perfusion the respective variables remained essentially unchanged compared with pre-CPB levels. CONCLUSIONS Using IABP as a surrogate to achieve pulsatile perfusion during CPB contributes significantly to lowered aortic pressure in the distal portion of aorta and impaired tissue perfusion of the kidneys. The results are focusing on effects that may contribute to organ dysfunction and acute kidney injury. Consequently, assessment of perfusion pressure distal to the balloon should be addressed whenever IABP is used during CPB.

Long-term prognostic value of cardiac troponin I and T versus creatine kinase-MB mass after cardiac surgery in low-risk patients with stable symptoms.

The long-term prognostic value of elevated cardiac biomarkers after elective cardiac surgery is not clear. The recent guidelines for diagnosing perioperative infarcts have advocated the use of similar thresholds for creatine kinase-MB (CK-MB) mass and the cardiac troponins. However, few previous data are available comparing these biomarkers after cardiac surgery, and it is not clear whether postoperative elevations of the troponins can be treated the same as elevations of CK-MB. We sought to compare the prognostic value of the cardiac troponins versus the CK-MB mass after elective cardiac surgery in low-risk patients with stable symptoms. A total of 204 consecutive patients undergoing cardiac surgery were included in the final analysis. Blood samples were drawn just before and 1 to 3 and 4 to 8 hours after the procedure, and every morning for 3 days thereafter. Patients with elevated baseline values were excluded. Using a cutoff value of 5 times the reference, patients with high and low values (controls) of CK-MB mass, cardiac troponin T (cTnT) and cardiac troponin I (cTnI) were compared. The median follow-up time was 92 months. None developed new Q-waves on the electrocardiogram. The incidence of the composite end point of all-cause mortality, readmission for acute coronary syndrome, and target vessel revascularization in the high CK-MB group was 41.2% compared to 21.8% in the controls (p = 0.004). The corresponding values for cTnT were 33.3% and 20.4% (p = 0.075) and for cTnI were 27.0% and 34.6% (p = 0.237). The p value in the isolated coronary artery bypass grafting subgroup (n = 156) was p = 0.043 for CK-MB, p = 0.137 for cTnT, and p = 0.795 for cTnI. High CK-MB (p = 0.001), ejection fraction (p = 0.002), and body mass index (p = 0.010) were the only variables independently related to reduced event-free survival. No such relation was found for high cTnT and cTnI. In conclusion, CK-MB was superior to the cardiac troponins (values > or =5 times the reference) in predicting long-term event-free survival after elective cardiac surgery in low-risk patients with stable symptoms undergoing coronary artery bypass grafting and/or valve surgery.

Long-Term Prognostic Value of Creatine Kinase-Myocardial Band Mass after Cardiac Surgery in Low-Risk Patients with Stable Angina

Objectives: The long-term prognostic value (>5 years) of elevated cardiac biomarkers after elective cardiac surgery is not clear. Most previous studies have included high-risk, unstable patients. The aim of this study was to determine the prognostic value of creatine kinase-myocardial band (CK-MB) mass after elective cardiac surgery in low-risk patients with stable angina. Methods: A total of 230 consecutive patients undergoing cardiac surgery were included in the final analysis. Blood samples were drawn just before and 1–3 and 4–8 h after the procedure, and every morning thereafter for 3 days. Using a cutoff value of 5 times the reference, 100 patients (43.6%) had peak CK-MB mass values ≥25 μg/l, and 130 patients had values <25 μg/l (defined as controls). No patient developed new Q waves on ECG. The median follow-up time was 95 months. Results: All-cause mortality and readmission for acute coronary syndromes were more frequent in the high-CK-MB group (30.0 vs. 17.9%, p = 0.022), as was target vessel revascularization (20.6 vs. 5.4%). Comparing the quartiles of peak CK-MB values in a Kaplan-Meier survival plot, event-free survival for the upper quartile (n = 60) was 68.3%, and for the lower quartile (n = 55), it was 83.6% (p = 0.046). In a multivariate logistic regression analysis, high CK-MB and ejection fraction were the only variables independently related to reduced event-free survival. Conclusions: CK-MB values ≥5 times the reference after elective cardiac surgery are associated with reduced long-term event-free survival.

Does infarct size influence loss of embolised 15-μm microspheres from ischaemic myocardium?

Andersen KS, Vik-Mo H. Stangeland L. Does infarct size influence loss of embolised 15-μm microspheres from ischaemic myocardium? Scand J Clin Lab Invest 1986; 46: 71-79.The relationship between myocardial infarct size and loss of 15-μm microspheres from ischaemic tissue was investigated in anaesthetized cats. Radioactive microspheres were injected in the left atrium before and 5 h after left anterior descending coronary artery occlusion. Left ventricular hypoperfused zone (HZ) averaged 36.6% and infarct size (IS) 31.6%. Thus, 86% of HZ evolved into necrosis. Preocclusion blood flow was lower in ischaemic (1.62 ml/min per g) compared with non-ischaemic myocardium (2.09, p=0.002). indicating 22% microsphere loss. In ischaemic subendocardium, oedema (3.7%) could account for the apparent loss. In ischaemic subepicardium, oedema was less pronounced and 18% physical sphere loss occurred. Subepicardial loss increased in proportion to IS and IS/HZ ratio -(r2 = 0.71; p < 0.005). Non-entrapment of 15-μm spheres in ...

Myocardial blood flow conditions at re-perfusion following acute ischaemia

The purpose of this study was to investigate the effect of re-perfusion upon distribution of radioactive microspheres in ischaemic myocardium. Ten anaesthetized cats were given 15-micron microspheres prior to left anterior coronary artery occlusion, at 1 h of occlusion, and after 1 h of subsequent re-perfusion. Pre-occlusion blood flow estimates were lower in tissue which had been ischaemic compared with nonischaemic regions in the same heart (1.44 versus 1.87 ml X min-1 X g-1, p less than 0.001), corresponding to 23% apparent loss. Loss also occurred in ischaemic right ventricular tissue (32%). In left ventricular ischaemic endocardium, apparent loss was due to development of oedema. Oedema was also significant in epicardial ischaemic tissue. Correction for oedema eliminated two-fifths of the loss, while three-fifths was due to physical loss. Oedema increased linearly with the level of re-perfusion. During re-perfusion, myocardial blood flow in previously ischaemic tissue was inhomogeneously distributed and, on average, 28% lower than in non-ischaemic myocardium. The 15-micron spheres appeared to pass through capillaries in the ischaemic subepicardium, but this process was not enhanced by reperfusion.

Effect of practolol on blood flow distribution in the myocardium during acute regional ischaemia in cats

The β-adrenergic blocking agent practolol was given to 11 cats with acute coronary artery ligation, and regional myocardial tissue blood flow was measured by the distribution of 15 μm labelled microspheres. Practolol reduced heart rate and cardiac contractility, but left ventricular end-diastolic pressure rose in eight animals. In three animals, however, the haemodynamics were essentially unchanged and these are referred to as non-responders. No changes in regional myocardial blood flow were observed after practolol administration, either in ischaemic, border or normal areas of the left ventricle. This indicates less serious imbalance between oxygen demand and delivery in ischaemic tissue. There was no endocardial/epicardial redistribution of tissue flow. Practolol did not appear to improve coronary perfusion, and beneficial clinical effects of practolol are therefore probably related to reduction of myocardial oxygen demands.