SERUM IONIZED CALCIUM CHANGES FOLLOWING CITRATED BLOOD TRANSFUSION IN ANAESTHETIZED MAN

Transcription

1 Brit. J. Anaesth. (1971), 43, 1108 SERUM IONIZED CALCIUM CHANGES FOLLOWING CITRATED BLOOD TRANSFUSION IN ANAESTHETIZED MAN BY J. E. HlNKLE AND L. H. COOPERMAN SUMMARY We measured the serum ionized calcium concentration in six patients who received ACD blood infusions during general anaesthesia and found the average decrease to be 0.5 mg/100 ml after 500 ml of blood and 0.6 mg/100 ml after 1000 ml of blood. However, the ion concentration increased a mean of 0.3 mg/100 ml 10 minutes following complete infusion of the blood. We also studied the effect of Pa^ on ionized calcium level in six patients under general anaesthesia who did not receive blood intraoperatively and found that the ion concentration varied directly with the Pa OO 2- An equation for a regression line relating Pa OO 2 and calcium ion concentration was derived. During anaesthesia and operation several interactions might be expected to alter radically ionized calcium levels, perhaps to the patient's detriment. One such change occurs with hypoventilation and hyperventilation for, in vitro at least, there is a direct relationship between Paoo 2 and ionized calcium (Pittinger, 1970). Another change might appear when citrated blood is infused, the excess citrate binding and decreasing ionized calcium (Bunker, 1966). The recent introduction of an electrode specifically sensitive to the ion has facilitated the measurement of this physiologically active portion of serum calcium (Moore, 1970). Using the electrode we have measured the alteration in ionized calcium occurring with blood transfusion and with changes in ventilation during anaesthesia and operation in man. METHOD Group A. We studied six patients of physical status I, II, or III, who were to undergo general anaesthesia and would receive intra-operatively whole blood stored in acid-citrate-dextrose solution. Their ages ranged from 24 to 75 years. Five patients underwent major abdominal procedures and one patient had a thoracotomy. All received a combination of narcotic and tranquillizer and a belladonna derivative as premedication; nitrous oxide, oxygen, tubocurarine and supplemental Innovar,* fluroxene, or enflurane (Ethrane) were used as anaes- * Fentanyl 0.05 mg/ml with droperidol 2.5 mg/ml. thetic agents. Intra-operative monitoring included nasopharyngeal temperature and direct arterial pressure via a 20-gauge short plastic catheter placed in the radial artery. Five minutes before the blood transfusion was started, control blood samples for arterial bloodgases, serum ionized and total calcium, protein, sodium and potassium were drawn. Thereafter, samples were drawn immediately after administration of every unit (approximately 500 ml) of blood and 10 minutes after complete infusion of the last unit. Surgery and anaesthesia were usually terminated shortly after the last sample was drawn. According to the needs of the patient, the time taken for infusion of any single unit varied from 15 to 37 minutes, except in one patient where two units were infused rapidly and simultaneously to replace blood lost acutely. In every case die consecutive units of blood were given in immediate succession, and during sampling no fluid other than blood was given. Body temperature fall was minimized as much as possible by wanning the administered blood. Samples for ionized calcium determination were drawn anaerobically into a plastic 20-ml syringe and immediately transferred via a 19-gauge needle JAMES E. HINKLE, M.D.; LEE H. COOPERMAN, M.D.; Department of Anesthesia, University of Pennsylvania, Philadelphia, Pennsylvania 19104, U.S.A. This work was supported in part by USPHS Research Training Grant 5-T10-GM and USPHS Research Grant 5-P01-GM

2 SERUM IONIZED CALCIUM CHANGES FOLLOWING TRANSFUSION 1109 into a glass Vacutainer without anticoagulant. With the Vacutainer completely filled with blood and remaining sealed, the samples were centrifuged after clotting had taken place. One ml of serum was withdrawn anaerobically into a tuberculin syringe for use in the Orion Model Calcium Activity Flow-Thru system and the Model 801 Digital ph/mv meter. Using the remaining serum we determined total calcium with Instrumentation Laboratories Model 153 atomic absorption spectrophotometer, total protein with the Bausch and Lomb serum protein meter and sodium and potassium with the Instrumentation Laboratories Model 143 Flame photometer. We also used the Instrumentation Laboratories Model 113-S2 ph/blood gas analyzer for measuring Pao2, Pa C o2 and ph. All measurements were made in duplicate, with reference standards used before and after each pair of measurements. Values given are the mean. Group B. Six candidates for peripheral or lower abdominal surgery under general anaesthesia were chosen to show the relationship between Pac O 2 and serum ionized calcium concentration. They were assigned physical status I or II, and their ages ranged from 26 to 74 years. Premedication consisted of various combinations of narcotic, sedative or ataractic drugs and a belladonna derivative. Because the general anaesthetic technique and fluid infusion were more easily controlled in this group, all patients received induction dose of thiopentone via an intravenous infusion of 5 per cent dextrose and water. Intubation of the trachea was accomplished with the aid of a paralyzing dose of suxamethonium or tubocurarine, and anaesthesia was maintained with 70 per cent nitrous oxide, 30 per cent oxygen, tubocurarine, and narcotic. Blood samples were taken from a 21-gauge needle in the radial artery. All patients were mechanically hyperventilated while end-tidal carbon dioxide was monitored by the Godart Capnograph. We added carbon dioxide to the inspired gas via a flowmeter on the anaesthetic machine to reach end-tidal carbon dioxide plateaux of 3, 4, 5.5, and 7 per cent. In three patients we progressed from the low to the high end of the spectrum and moved in the opposite direction in the other three patients. Fifteen minutes of steady-state anaesthesia were maintained at the first plateau prior to obtaining a complete set of blood-gases and a sample for determination of ionized serum calcium, collected as described previously. Three minutes later another set of samples for Paco2, ph and ionized calcium were drawn to demonstrate that the patient had stabilized at the first plateau. From 3 to 10 minutes were needed to reach the next plateau after which 4 minutes elapsed before samples were drawn as described above. To illustrate whether ionized calcium changes continued after the last plateau was reached, duplicate samples again were taken 3 minutes apart. Blood-gases, serum ionized calcium and total calcium concentrations, and serum total protein were measured as they were in group A. Serum sodium and potassium were not measured. Temperature and oxygenation of all patients was kept constant, and no one received more than 750 ml of 5 per cent dextrose and water during the time of blood sampling. RESULTS Figure 1 illustrates the change in ionized calcium in mg/100 ml of serum for group A. In every patient it decreased markedly with infusion of 500 ml of ACD blood and further decreased in the four who received at least 1000 ml. After patient No. 3 received a second 1000 ml rapidly, his ionized calcium fell even further although an un- a? X 5-as J 0 M 2 ' 2 E-Q5 g-o- 6 z i" 07 C O.9 V PT. 1 *Pt2 Opt3 A pt.4 Pt.5 Pt ' ACD BLOOD TRANSFUSED ml * 10 mln Post-Trans FIG. 1 Changes in serum ionized calcium concentration with transfusion of ACD blood and 10 minutes following completion of transfusion in six anaesthetized patients.

3 1110 BRITISH JOURNAL OF ANAESTHESIA Patient No ml blood in 2 1 TABLE I (GROUP A) Effect of ACD blood on ionized calcium concentration. Paco 2 (mmhg) Blood PH Ionized (mg/looml) Actual change in (mg/100 ml) Expected change in based only on change in Paoo 2 (mg/100 ml) explained rise appeared after the fifth unit. Ten minutes following completion of the transfusion, the values for calcium ion increased impressively towards the control value in all but patient No. 3 where the measurement could not be made. The ionized calcium content of the transfused blood itself was immeasurably low. From the data shown in table I, we calculated that the ionized calcium level fell by a mean of 0.5 mg/100 ml (SE 0.05) immediately following infusion of 500 ml of blood and a mean 0.6 mg/100 ml (SE 0.07) following 1000 ml of blood. Ten minutes after transfusion was completed the ionized calcium level increased by a mean of 0.3 mg/100 ml (SE 0.04). Serum total calcium, protein, sodium and potassium were observed not to change significantly in any patient. With group B, as shown in table II, blood ph changed in each patient according to the change in Paco2, there being a direct relationship between ionized calcium and Paoo 2 (Pittinger, 1970). In four patients ionized calcium did not vary significantly while the Pa C o2 was held constant at the first and last plateaux. In patients 1 and 6 the calcium determinations varied beyond the 95 per cent confidence limits ( mg/100 ml) of the electrode measurement (Moore, 1969) when the Pa C02 was at its highest level; the cause of this is undetermined. In figure 2 we have plotted change in ionized calcium measured in mg/100 ml of serum as a function of change in Pa 002 in mm Hg. The regression line showing the relationship between our variables was derived by the Hewlett-Packard 9125A Calculator Plotter, the slope being 0.01%, the y intercept , and the correlation coefficient Therefore, we were able to estimate what change in ionized calcium could be expected as a result of Pac O 2 change in group A by using the equation y = X The expected changes are recorded in table I. We found no significant change in serum protein or total calcium with change in

4 SERUM IONIZED CALCIUM CHANGES FOLLOWING TRANSFUSION 1111 TABLE II (GROUP B) Effect of Paco* on ionized calcium concentration. Patient Paco 2 Ionized Ca + + No. (mmhg) Blood ph (mg/100 ml) CHANGE IN PoCOzmm Hg FIG. 2 Regression line showing relationship between change in Paco 2 and change in ionized calcium concentration during general anaesthesia. DISCUSSION From the data accumulated in the study of these twelve patients under general anaesthesia, two physiological processes are apparent. First, in contrast to the opinion of Perkins, Thacher and Rolfs (1965), transfusion of citrated bank blood decreases the concentration of calcium ion in the serum, and when the units of blood are given in rapid succession the ionized calcium can be depleted to extremely low levels. However, within 10 minutes the ion concentration rose toward that measured prior to the blood infusion. Killen and associates (1969) found a similar sequence of events in their study involving rapid infusion of ACD solution into dogs. Parenthetically, one patient not included in our series, was found to have an ionized calcium of only 1.4 mg/100 ml after transfusion of approximately 30 units of blood in 3 hours. Second, the ionized calcium concentration can be raised or lowered by similarly changing the Pa C0 2 of the anaesthetized patient. Pittinger (1970) demonstrated this phenomenon in vitro and similarly derived the equation for a regression line relating ionized calcium and ph. Presumably, our results in group B reflect a shift from protein bound to ionized calcium with a fall in ph as Pco 2 rises (Bunker, 1966). However, in group A changes in blood ph are inconsistent with changes in ionized calcium or Pa OO 2 and, therefore, are assumed to be the result of the combined effects of these changes plus the acidity of stored blood (Bunker, 1966). By comparing the actual change in ionized calcium in group A with the changes expected on the basis of Pa C 02 change, it is impressive to see how potent citrated blood can be in binding the calcium ion. Equally impressive is the quick rise of the ion concentration toward the control level after blood infusion has ceased. Since the calcium ion is involved in such processes as excitation conduction, membrane phenomena, muscle contraction and relaxation, blood clotting, and enzyme activation (Oreskes et al., 1968), it is important to realize what factors can alter its concentration, particularly during anaesthesia. The Flow-Thru calcium electrode supplies a practical and adequate means of measuring calcium ion level. A wide variety of studies, such as the effect of heparin, muscle relaxants, antibiotics,

5 1112 BRITISH JOURNAL OF ANAESTHESIA or other pharmacological agents on calcium ionization, need to be carried out in the anaesthetized patient. REFERENCES Bunker, J. P. (1966). Metabolic effects of blood transfusion. Anesthesiology, 27, 446. Killen, D. A., Gower, R. E., Grogan, E. L., and Collins, H. A. (1969). Course of plasma ionized calcium following rapid infusion of acid citrate dextrose solution. Surg. Forum, 20, 95. Moore, E. W. (1969). Studies with ion exchange calcium electrodes in biological fluids: some applications in biomedical research and clinical medicine; in Ion Selective Electrodes (ed. Durst, R. A.), p Washington: National Bureau of Standards Special Publication, 314, U.S. Department of Commerce. (1970). Ionized calcium in normal serum, ultrafiltrates, and whole blood determined by ion exchange electrodes. J. din. Invest., 49, 318. Oreskes, I., Hirsch, C, Douglas, K. S., and Kupfer, S. (1968). Measurement of ionized calcium in human plasma with a calcium selective electrode. Clirt. chim. Ada, 21, 303. Perkins, H. A., Thacher, C, and Rolfs, M. R. (1965). Measurement of calcium ion levels during massive transfusion of citrated blood. Bibl. haemat. (Basel), 23, Pittinger, C. B. (1970). ph and streptomycin influences upon ionic calcium in serum. Anesth. Analg. Curr. Res., 49, 540. VARIATIONS DES CONCENTRATIONS SERIQUES DE CALCIUM IONISE A LA SUITE DE TRANSFUSIONS DE SANG CITRATE, CHEZ DES SUJETS HUMAINS ANESTHESIES SOMMAIRE Nous avons mesure les concentrations seriques de calcium ionise chez six malades qui avaient recu des transfusions de sang citrate au cours d'une anesthisie generale et avons constate l'existence d'une diminution de 0,5 mg/100 ml, apres administration de 500 ml de sang et de 0,6 mg/100 ml, apres administration de 1000 ml de sang. Neanmoins, la concentration ionique s'est accrue en moyenne de 0,3 mg/100 ml pendant les 10 minutes ayant suivi la transfusion totale du sang. Nous avons egalement etudie les effets de la tension en CO 2, Paoo 2 sur le taux de calcium ionise, chez six malades soumis a une anesthesie generale et qui n'avaient pas fait Pobjet d'une transfusion en cours d'intervention. Nous avons constati que la concentration ionique evoluait en rapport direct avec Paco 2. On en a deduit une equation pour une ligne de regression reliant Paco 2 a la concentration en calcium ionique. VERANDERUNGEN DES IONISIERTEN KALZIUMS IM SERUM NACH TRANSFUSION VON ZITRATBLUT BEIM MENSCHEN WAHREND DER NARKOSE ZUSAMMENFASSUNG Wir haben bei sechs Patienten, die Infusionen von ACD- Blut wahrend einer allgemeinen Narkose erhielten, das ionisierte Kalzium im Serum gemessen. Es fand sich eine durchschnittliche Abnahme von 0,5 mg/100 ml nach 500 ml Blut und von 0,6 mg/100 ml nach 1000 ml Blut. Die Ionen-Konzentration stieg jedoch 10 Minuten nach Abschlufl der Bluttransfusion um durchschnittlich 0,3 mg/100 ml an. Wir utersuchten aufierdem die Wirkung von Pco 2 auf die Hohe des ionisierten Kalziums bei 6 Patienten in Allgemeinnarkose, die intraoperativ kein Blut erhielten und stellten fest, dafi die Ionen-Konzentration direkt mit dem Pco 2 variierte. Fur die Beziehung zwischen Pco 2 und Kalzium-Ionenkonzentration wurde eine Gleichung fur die Regressionslinie abgeleitet. CAMBIOS EN EL CALCIO IONIZADO DEL SUERO DESPUES DE TRANSFUSION DE SANGRE CITRATADA EN EL HOMBRE ANESTESIADO RESUMEN Hemos medido la concentracion de calcio ionizado en el suero de seis pacientes que recibieron infusiones de sangre ACD durante la anestesia general y encontramos que la disminucion media fue de 0,5 mg/100 ml despues de 500 ml de sangre y 0,6 mg/100 ml despues de 1000 ml de sangre. Sin embargo, la concentracion de iones aumento en una media de 0,3 mg/100 ml 10 minutos despues de terminar la infusion de sangre. Tambien hemos estudiado el efecto de la Paco 2 sobre el nivel de calcio ionizado en seis pacientes bajo anestesia general que no recibieron sangre intraoperatoriamente y encontramos que la concentracion ionica variaba directamente con la Paco.. Fue derivada una ecuacion para una linea de regresion que relaciona la Paco 2 y la concentracion de iones de calcio.