The use of the iSTAT portable analyzer in patients undergoing cardiopulmonary bypass

Objective. To evaluate the utility of the iSTAT blood analyzer, a bedside device for hematocrit, sodium, potassium, and glucose measurement during cardiopulmonary bypass (CPB).Methods. Forty patients scheduled for elective CPB were evaluated prospectively. In addition to using the iSTAT analyzer, blood samples were analyzed at four time points: following induction of anesthetic, 10 min. after initiation of CPB, 60 min. after initiation of CPB, and following heparin neutralization by protamine. Blood glucose concentration was measured by the hospital laboratory using a Kodak Analyzer and by a glucose meter, electrolytes were evaluated by the Kodak Analyzer and BGE (a device which is commonly used for satellite laboratory determinations of electrolyte and blood gas results), and hematocrit samples were measured by the hospital laboratory using an NE 8,000 and a centrifuge. The means and standard deviations of the differences between the methods were calculated.Results. The hematocrit values determined by the iSTAT machine, when adjusted for the level of total protein (according to manufacturer's directions), differed from the laboratory values by 0.53 = 1.46 percentage points. An alternative to measuring total protein and making the adjustment is simply adding 1 % to the hematocrit in the pre-CPB period and 3% on-CPB or post-CPB, which we found to yield values that differed from the laboratory by 0.52 ± 1.42 percentage points. For all four tests (hematocrit, sodium, potassium, and glucose) the iSTAT had a similar relationship to the laboratory values as did the other commonly used means (centrifuge, BGE, and glucose meter) of clinical evaluation.Conclusion. In summary, we found that in patients undergoing CPB, the iSTAT values agreed sufficiently well with standard laboratory values and that the iSTAT instrument can be relied upon for bedside measurements.Presented in part at the Annual Meeting of the Society of Cardiovascular Anesthesiologists, Philadelphia, PA, May 1995, and at the 70th meeting of the IARS, Washington DC, March 1996. Supported in part by a grant by iSTAT Corporation.     

Biphasic action of intravenous ethanol on dog exocrine pancreatic secretion

The effect of a 20-min intravenous infusion of 1 g/kg of ethanol on a 15% (w/w) solution in isotonic saline on pancreatic secretion was determined in six conscious Beagle dogs provided with Thomas cannulae. Ethanol was given on a background of a prolonged infusion of 0.5 CU/kg/hr of secretin alone or secretin plus either different doses of cerulein (12.5–200 ng/kg/hr), 3 μg/kg/hr of pentagastrin, or 200 μg/kg/hr bethanechol. Intravenous ethanol had a biphasic action on pancreatic secretion: inhibition during the first 40 min followed by stimulation. When compared to control experiments with intravenous infusion of saline, the inhibition was statistically significant only for volume and bicarbonate output against a background of pentagastrin and for protein output against a background of bethanechol. We propose that alcohol inhibits acetylcholine-mediated protein secretion. We delayed stimulatory effect of ethanol was statistically significant for both ecobolic (protein output) and hydralatic (water and bicarbonate) secretion during infusion of secretin plus 12.5–25 ng/kg/hr cerulein, but not with doses of 50 ng/kg/hr. Although the plateau of secretion before alcohol was roughly similar in the experiments using cerulein and bethanechol, ethanol inhibited protein output and had no effect on bicarbonate output during stimulation with bethanechol Therefore, the effects of alcohol on pancreatic secretion are influenced by both the type of stimulation and its intensity (dosage).     

Erythropoiesis and renal transplant pregnancy

OBJECTIVE: To examine erythropoiesis in renal transplant pregnancies. METHODS: Retrospective cohort study of 30 renal transplant cases and 30 age, smoking and parity-matched healthy controls with normal index pregnancy. Retrospective chart review and assay of frozen antenatal serum (for serum erythropoietin concentration [serum EPO]), transferrin receptor protein [TfR], ferritin, folate and B12) were performed. The linear regression equation for normal pregnancy controls was used to calculate predicted [serum EPO] and the observed/predicted (O/P) log [serum EPO] was plotted. The relationship between [serum EPO] and haemoglobin (Hb) among transplant cases was considered to be different from that among controls if the slope of the O/P log [serum EPO] versus Hb regression was significantly different from zero. RESULTS: The transplant (14 cadaveric) to conception interval was (median [range]) 33.5 [4, 189] months. Immunosuppressants were azathioprine (n = 25), cyclosporine (n = 22) and/or prednisone (n = 25). Cases were more often primiparous (20 vs. 7 [controls]; p = 0.01), had pre-existent hypertension (20 vs. 0 [controls]; p < 0.001), developed new/increased hypertension or pre-eclampsia (28 vs. 0 [controls]; p < 0.001) and an antenatal rise in creatinine (14 vs. 2 [controls]; p < 0.001). In early pregnancy, cases had similar EPO (15.2 [2.6, 84.6] vs. 15.7 [6.4, 41.0] [controls] U/L) but lower Hb (101 [65, 129] vs. 116 [106, 150] g/L; p < 0.001). Twenty-two (73%) cases had Hb < 100 g/L (vs. 4 [controls]; p < 0.0001); Hb was comparable at 6 wk postpartum. With advancing gestational age (GA), Hb remained stable and serum EPO increased in both groups. The slope of the O/P log [serum EPO] versus Hb for transplant cases was significantly different from zero within both the 17-28 wk (slope +/- SEM: 0.010 +/- 0.002; p < 0.0001) and the 29-42 wk GA categories (0.006 +/- 0.003; p = 0.02). Cases showed smaller rises in serum TfR (change 481 [- 1471, 2780]) vs. 1119 [- 698, 4195] [controls] ng/mL; p = 0.005). CONCLUSIONS: Anaemia frequently complicates renal transplant pregnancies, in which serum EPO is inappropriately low and the rate of erythropoiesis blunted.     

Zinc replenishment reduces esophageal cell proliferation and N- nitrosomethylbenzylamine (NMBA)-induced esophageal tumor incidence in zinc-deficient rats

Previous work has shown that sustained increased and decreased cell proliferation, induced by dietary zinc deficiency and caloric restriction respectively, influence the course of N- nitrosomethylbenzylamine (NMBA)-induced esophageal carcinogenesis in rats. The present study considered whether the increased cell proliferation and esophageal tumor incidence induced by zinc deficiency are reversed upon zinc replenishment. Weanling rats were maintained initially on a deficient diet containing 4 p.p.m. zinc. After 5 weeks, carcinogen-treated animals were given six intragastric doses of NMBA (2 mg/kg twice weekly). Controls were untreated. After the second NMBA dose, the rats were divided into three dietary groups. One group was continued on the deficient diet, while the other two groups were switched to diets containing either 75 or 200 p.p.m. zinc, with half of the members in each group fed ad libitum and half pair-fed with deficient rats. NMBA-untreated controls were similarly replenished. At various time points, esophageal cell proliferation was assessed in five animals from each group by immunohistochemical detection of cells in S phase, with in vivo 5-bromo-2'deoxyuridine labeling. At 11 weeks after the first dose, esophageal tumor incidence was greatly reduced, from 100% in the deficient group to 26 and 14% respectively in the replenished groups fed ad libitum 75 and 200 p.p.m. zinc and to 14 and 11% respectively in the replenished groups pair-fed 75 and 200 p.p.m. zinc. In addition, the number of tumors per esophagus was reduced from 9.93 +/- 4.25 in deficient rats, to a range of 0.11 +/- 0.31-0.30 +/- 0.54 in replenished animals. Following zinc replenishment, esophageal cell proliferation, as measured by labeling index (LI), the number of labeled cells and the total number of cells, was markedly decreased in NMBA-untreated and -treated esophagi as compared with those in corresponding deficient esophagi. Thus, the esophageal cell proliferation induced by zinc deficiency is reversed by zinc replenishment and replenished animals have a markedly lower incidence of esophageal tumors.      

Breast cancer in a 6-year-old child

A 6-year-old girl presented for a second opinion with a 1-year history of an enlarging soft tissue mass just lateral to the right areola. She had been seen by a pediatric surgeon elsewhere who reassured the parents that the lesion was benign. Ultrasound scan showed a 1.5- x 1.5-cm cystic structure adjacent to the right breast bud. Excisional biopsy results showed secretory ductal adenocarcinoma. Modified radical mastectomy with axillary node dissection was performed. All 11 nodes were negative for metastatic disease. She is now disease free 3 years after diagnosis. Estrogen-progesterone receptors were negative, as was screening for BCR 1 and 2. This is the first report of cytogenetics showing an abnormal cell line with a reciprocal translocation between 12p and 15q. Although breast cancer is extremely rare in children, a history of a painless, enlarging, firm breast mass should raise concern about possible neoplastic disease. Cystic appearance on ultrasound scan caused by the pseudocapsule around the tumor may be a marker for secretory carcinoma. Histological evaluation of all suspicious masses should be obtained. Because of the risk of local recurrence and axillary metastases, the authors recommend modified radical mastectomy with axillary node dissection for children with secretory carcinoma of the breast.     

Carotid duplex imaging: variation and validation

BACKGROUND: Duplex imaging is increasingly used as the only investigation before carotid endarterectomy, but many different criteria exist in the literature for the detection of a severe (70-99 per cent) carotid stenosis. This study aimed to investigate current practice in carotid duplex imaging in Great Britain and Ireland. METHODS: A postal questionnaire was sent to 86 vascular surgical units. RESULTS: The median number of scans performed per year was 450 (range 60-4500). Thirty-six per cent of units who responded used peak systolic : end diastolic velocity ratio to calculate carotid stenosis. Overall, nine different major duplex criteria were used to grade carotid stenosis in 14 different systems of percentage bands. Only 51 per cent of units verified their duplex criteria against angiography. Eighteen per cent of units used two or more different types of duplex scanner and applied the same diagnostic criteria to each machine. CONCLUSION: A wide variation in diagnostic duplex criteria and methods of grading stenosis exists among vascular units. Internal validation is not performed routinely. Standardization of duplex criteria would ensure greater consistency, but would not replace the need for validation of results within each unit.