Assessment of neurological injury due to circulatory arrest during profound hypothermia. An experimental study in vertebrates.

To investigate brain changes in induced deep core hypothermia (15 degrees C) with circulatory arrest, five groups of neonatal pigs were subjected to cardiopulmonary bypass (CPB), with circulatory arrest (CA) periods varying from 70-120 min. The parameters analysed were: 1. Histology and electron microscopy of the brain six hours post-CPB, 2. Creatinophosphokinase (CPK) from cerebrospinal fluid (CSF), 3. Vasointestinal neuropeptide (VIP) and 7B2 specific neuropeptide both in plasma and brain tissue. The earliest morphological changes were seen after 90 min CA and were highly significant after 120 min arrest. These changes involved mainly the Purkinje cells of the interior half of the cerebellum with vacuolation in their cytoplasm. A rise in CPK in CSF occurred in all piglet-groups. The differences among the various groups were highly significant at 2 and 5 h post-CPB. (P < 0.05). Statistically significant differences were not exhibited among the various groups both in serum and brain tissue total mean values of VIP and 7B2 neuropeptides. We suggest that 1. The cerebellar region is the most sensitive where ischemic lesions attain their maximal severity and extent; the frequency and pattern of selective vulnerability of the cerebellum may be related primarily to its pattern of blood supply 2. The maximum time of CA without histopathological sequelae should not exceed 70 min.

Postoperative myocardial damage in patients with coronary artery disease undergoing major non cardiac surgery.

A prospective study was carried out in a group of 50 patients with coronary artery disease, presenting for major non-cardiac surgery, to investigate the timing and incidence of further perioperative myocardial damage. A standardised anaesthetic was used. A standard 12-lead ECG was taken immediately before surgery and at 24, 48, and 72 hr after the start of anaesthesia. Blood samples were taken immediately preoperatively and at 6, 24, 48, and 72 hr after anaesthesia for total CK and CK-MB assay. Thirty-three patients (66%) showed ECG evidence suggestive of further infarction, and of these, two (4%) died in the immediate perioperative period. The first ECG change occurred in 27/31 (87%) by 24 hr, in 3/31 (10%) by 48 hr, and 1/31 (3%) by 72 hr. Twenty-nine patients (58%) including the two deaths showed CK-MB enzyme changes. The first elevation in CK-MB was nil at 6 hr and 72 hr, with 23/27 (85%) at 24 hr, and 4/27 (15%) at 48 hr. In 22/50 (44%) ECG and enzymes were correlative. Goldman and Cooperman risk indices were calculated for each patient. The Cooperman risk index was superior to the Goldman scale in the correlation of observed with predicted myocardial morbidity. Patients with ECG changes only before surgery were just as liable to further myocardial damage as those patients with ECG changes and a documented history of a previous infarct and/or symptoms. Myocardial damage is maximal in the first 24 hr after surgery, and may not be adequately predicted by current risk indices.

Early postoperative myocardial morbidity in patients with coronary artery disease undergoing major non-cardiac surgery: correlation with perioperative ischaemia.

As a part of a study assessing early postoperative myocardial morbidity in 50 patients with active coronary artery disease undergoing major non-cardiac surgery, the ECG was monitored continuously for 24 hr after the onset of anaesthesia, using a frequency modulated (FM) Holter monitor. Concurrent automated blood pressure and pulse were measured non-invasively at three-minute intervals during anaesthesia and subsequently at five-minute intervals. Thirty patients were monitored with two-site ECG recordings, from modified V1 and V5 (Group A). Twenty patients had seventeen-site ECG monitoring, multiplexing a four by four array of precordial electrodes onto one channel of the frequency modulated recorder (Group B). Tapes were analyzed for noise, supraventricular and ventricular dysrythmias, runs of tachy- and bradycardia, and ST segment changes. These data were correlated with serial standard 12-lead ECGs and CK-MB assay in the 72 hr after surgery. Seven tapes from Group A could not be analyzed. Change (greater than 1 mm) on ST monitoring from both Groups A (14/23), B (14/20), correlated with serial 12-lead ECG and/or CK-MB changes. The majority of first ST change 19/28 (70%) occurred after anaesthesia. In 14/28 (50%) ST change occurred during episodes of tachycardia and elevated blood pressure (greater than 20% above baseline). Nine patients (9/23) in Group A had no ST change; however, six had serial 12-lead ECG and/or CK-MB changes. Six patients (6/20) in Group B had no ST changes, and none of these patients had any change of serial 12-lead ECGs or CK-MB assay. No patient complained of chest pain during the Holter monitoring period. Continual monitoring of heart rate and blood pressure and accurate ST monitoring are essential to detect and treat perioperative myocardial ischemia. A multiple-lead precordial system is substantially more sensitive than traditional two-lead ECG holter monitoring in detecting myocardial ischaemia.

A comparison of cellulose acetate immunofixation with polyacrylamide gel electrophoresis for the detection of oligoclonal bands in unconcentrated cerebrospinal fluid.

Two methods of electrophoresis for the detection of oligoclonal bands in unconcentrated CSF were compared. A sample of 98 routine CSFs yielded 18 positives by polyacrylamide gel electrophoresis (PAGE) while cellulose acetate electrophoresis with immunofixation (CAIF) gave 13 positives (72% of the PAGE findings). Despite the loss of sensitivity the cellulose acetate electrophoresis was easier to interpret and more suited to a routine hospital laboratory.

A pilot study of the effect of Gemfibrozil on some haematological parameters.

In a double-blind 13 week study the effects of Gemfibrozil were compared with placebo. Gemfibrozil was given to 10 patients with evidence of severe atherosclerosis; four similar patients acted as controls. As expected, in the treated group, total cholesterol and triglycerides decreased significantly and HDL cholesterol increased. The Fibrinogen did not change although the ESR increased markedly and the heparin neutralizing activity (HNA) of the plasma decreased (p = 0.01). The antithrombic activity increased. The change in the HNA correlated weakly to the total cholesterol both before and during treatment. These findings show that some of the effects of Gemfibrozil on atherosclerotic humans are similar to those of Clofibrate but others are different.

Detection limits for protein after electrophoresis on cellulose acetate.

The detection limits for protein, when stained with nigrosine after electrophoresis on cellulose acetate, was studied and shown to be: albumin, 3-0 ng; transferrin, 0.8 ng; and Bence-Jones protein, 0.8 ng. This was less than one-hundredth of the previously reported levels. Immunofixation, although useful for identification, did not lower the detection limit for Bence-Jones protein.

Comparison of three automated methods of serum tirglyceride analysis.

Two new automated methods for serum triglyceride analysis are described and compared with each other and with an established chemical method. They are a chemical method requiring no glycerol blank correction and a commercially available fully enzymatic method requiring no prior lipid extraction. Both methods had higher quality control precision and faster sampling rates than the established method. Comparison of duplicate analyses of a random series of serum samples by all three methods gave a closer correlation between the new methods than between either and the conventional method.