Saline Infusion, Acidosis, and the Stewart Approach Article Supports

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Anesthesiology 2000; 92:624 0 2000 American Society of Anesthesiologists, Inc Lippincon Williams & Wilkins, Inc. Saline Infusion, Acidosis, and the Stewart Approach Downloaded from http://pubs.asahq.org/anesthesiology/article-pdf/92/2/624/403535/0000542-200002000-00054.pdf by guest on 27 September 2021 To the Editor:-The report by Scheingraber et al.’ highlights the David A. Story, M.B.B.S.(Hon), B.M.Sci(Hon), F.A.N.Z.C.A. phenomenon of acidemia after infusion of 0.9%)saline in the peri- Staff Anaesthetist operative period. The accompanying editorial’ discusses several Department of Anaesthesia relevant points; however, we are disappointed that neither the [email protected] article nor the editorial addresses the central issue of the relative Frank Liskaser, M.B.B.S., F.A.N.Z.C.A. merits of the Stewart approachg in describing acid- base physiology Staff Anaesthetist and pathophysiology. Department of Anaesthesia Compared with the Henderson-Hasselbalch approach, the Stewart Rinaldo Bellorno, M.B.B.S., M.D., F.R.A.C.P. approach has a number of appealing features. (1) The control of Associate Professor acid- base and water homeostasis can be explained in terms of both Intensivist and Director of Research sodium and chloride regulation. (2) Acid-base status is partly con- Department of Intensive Care trolled by a number of plasma electrolytes, notably sodium and chlo- Austin and Repatriation Medical Centre ride. These electrolytes can be manipulated in the clinical setting to Austin Hospital Heidelberg optimize acid-base status. (3) The factors controlling acid- base status Melbourne, Victoria 3084, Australia are independent. Criticisms of the Henderson-Haselbalch approach include a lack of independence between carbon dioxide and bicarbonate.4 (4) The Henderson-Hasselbalch approach does not allow assess- References ment of nonvolatile buffers, whereas the Stewart approach explicitly 1. Scheingraher S, Rehm M, Sehmisch C, Finsterer U: Rapid saline includes assessment of weak acids.4 infusion produces hyperchloremic acidosis in patients undergoing Comparison of the Stewart and Henderson-Hasselbalch approaches gynecologic surgery. ANES1’HESIOI.OGY 1999; 90: 1265-70 is complicated by the fact that both approaches adequately describe 2. Prough DS, Bidani A: Hyperchloremic metabolic acidosis is a the acid- base end point, as Scheingraber et al. demonstrate.’ Further predictable consequence of intraoperative infusion of 0.9%saline (ed- study is required to determine which approach better describes the itorial). ANESTHESIOLOGY1999; 90: 1247-9 mechanisms of acid- base physiology. 3. Stewart PA: Modem quantitative acid-base chemistry. Can Previous animal studies5 have suggested that the alkalinizing J Physiol Pharmacol 1983; 61:1444-61 effect of lactate-containing solutions in acute resuscitation is time 4. Fencl V, Leith DE: Stewart’s quantitative acid-base chemistry: dependent, which underscores the concept of lactate as a strong Applications in biology and medicine. Respir Physiol 1993; 91: ion. The removal of lactate from the circulation will increase the 1-16 strong ion difference and reduce acidosis.3 This effect may be 5. Traverso LW, Lee WP, Langford MJ: Fluid resuscitation after an supplemented by further increases in the strong ion difference otherwise fatal hemorrhage: I Crystalloid solutions. J Trauma 1986; associated with lactate metabolism”; in contrast, added chloride 261168-75 6. White SA, Goldhill DR: Is Hartmann’s the solution? Anaesthesia ions appear to persist longer in the circulation. Subsequently, a 1997; 521422-7. smaller strong ion difference is maintained along with greater acidosis, as seen in the report by Scheingraber et al.‘ (Accepted for publication September 2.3, 1999.1

AnesthesioIoLy 2000; 92624-5 0 2000 American Society of Anesthesiologists, Inc. Lippincott Williams & Wiurins, Inc. Article Supports Findings of Previous Comparison

To the Editor:-The article by Scheingraber et al.’ supports the find- administration of “unusually large volumes of saline.”’ The study was, ings of a previous comparison of saline with a balanced salt solution in fact, a randomized-controlledcomparison of saline with a balanced carried out by McFarlane and Lee in 1994.’ The accompanying editorial salt solution, both of which were administered at 15 ml . kg-’ . h-’. by Prough and Bidani described this study as a clinical report of the This rate of administration was half the rate used by Scheingraber et

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al.’ McFarlane and Lee studied 30 patients with a mean weight of G. B. Drummond, M.B., Ch.B., F.R.C.A. approximately 60 kg who were undergoing surgery that lasted approx- Department of Anaesthetics imately 200 min; therefore, the mean volume of fluid administered Royal Infirmary would be approximately 3 1, which cannot be considered “unusually Edinburgh, Scotland large.” Unfortunately, neither the title of this article nor the key words include the terms “randomizedcomparison,” “acidosis,”or “hyperchlo- References remia,” which may explain why the article was neglected. The report is completely substantiated by the subsequent article by Scheingraber 1. Scheingraber S, Rehm M, Sehmisch C, Finsterer U: Rapid saline Downloaded from http://pubs.asahq.org/anesthesiology/article-pdf/92/2/624/403535/0000542-200002000-00054.pdf by guest on 27 September 2021 infusion produces hyperchloremic acidosis in patients undergoing et d,’although the acidosis caused by the administration of the saline gynecologic surgery. ANESTHESIOLOGY1999; 90:1265-70 solution was less severe because the dose of saline was less. In addi- 2. McFarlane C, Lee A: A comparison of Plasmalyte 148 and 0.9?4 tion, McFarlane and LeeZreported that the plasma chloride values had saline for intra-operative fluid replacement. Anaesthesia 1994; returned to normal after 24 h. 49779 - 81 I agree wholeheartedly with the editorid comment’ that the Stewart 3. Prough DS, Bidani A: Hyperchloremic metabolic acidosis is a approach to acid- base balance contributes greatly to understandingthese predictable consequence of intraoperative infusion of 0.9% saline. phenomena, and that current thinking is often muddled, as shown by a ANESTHESOLOCY 1999; 90:1247-9 recent survey4 and the subsequent ~orrespondence.~Much of this debate, 4. White SA, Goldhill DR: Is Hartmann’s the solution? Anaesthesia regardless of whether it acknowledges previous studies, fails to properly 1997; 52:422-7 address the potential harm from hyperchloremia. Some argue that hyper- 5. Drummond GB: Is Hartmann’s the solution? (correspondence) chloremia is harmful,” whereas others, including the authors of the edi- Anaesthesia 1997; 52: 918-9 torial, consider that hyperchloremia is not harmful,’ but cite no support- 6. Russo MA: Dilutional acidosis: A nonentity?ANESTHESIOLOGY 1997; ing evidence. If hyperchloremia has important adverse effects, why have 87:1010 - 1 7. Williams EL, Hildebrand KL, McCormick SA, Redel MJ: The effect they not yet become apparent? A recent volunteer study suggests that of intravenous lacated Ringer’s solution versus 0.9% sodium chloride subjective mental changes can OCCLU more readily after sodium chloride solution on serum osmolality in human volunteers. Anesth Analg 1999; administration.‘ A prospective randomized study of clinical outcome may 88:999-1003 be justified because it is outcome rather than surrogate measures, such as biochemical values, that are of clinical importance. (Accepted for publication September 23, 1999.)

Anesthesiology 2000,92:625- 6 0 2000 American Society of Anesthesiologists, Inc Lippincott Williams & Wilkins, Inc. Avoiding Iatrogenic Hyperchloremic Acidosis-Call for a New Crystalloid Fluid

To the Editor:-Scheingraber et al.‘ have provided further evidence resuscitation. This avoidance may be more easily said than done; one that hyperchloremia causes acidosis and draw attention to this clinical consequence of massive resuscitation is increasing hyperkalemia problem. However, the authors suggest that iatrogenic hyperchlor- caused by the use of blood products. The hyperkalemia is of special emic acidosis may be benign. This may be true in relatively healthy concern if the patient is already in renal failure. Substituting 0.9%saline patients subjected to Limited hyperchloremic insults, because the hy- by the commercially available normochloremic fluids such as lactated perchloremia is corrected by the subsequent chloruresis. The concern Ringer’s injection, Normosol (Abbott), and Plasma-Lyte (Baxter) is is the effect of more severe hyperchloremia secondary to aggressive likely to compound the problem of hyperkalemia, because these fluids fluid resuscitation in acutely ill patients undergoing major trauma contain potassium. This situation is best exemplified by the the case surgery, burn debridements, vascular surgery, and liver transplanta- report where a patient undergoing bilateral nephrectomy for polycys- tion. In vascular surgery, lactic and carbonic acid load from the distal tic kidney disease required 20 I normal saline, along with blood products4 segment may be superimposed on the iatrogenic hyperchloremic aci- One means of avoiding hyperchloremia and hyperkalemia is to use a dosis at the time of unclamping the aorta. fluid with the following composition: Nat = 140 mEq/l, C1- = 100 Animal studies suggest that hyperchloremia causes renal vasocon- mEq/l, and lactate or bicarbonate = 40 mEq/l. Currently, the only way striction‘.’ and its affect on other organ functions are not known. one can get such normochloremic- and potassium-free fluid is to have It is a matter of concern that hyperchloremia may be playing a the hospital pharmacy prepare it on request from the physician. contributory if not a major role in the pathogenesis of renal insuffi- Clearly, further studies are needed to better understand the patho- ciency or failure that may be frequently seen in patients requiring physiology of hyperchloremic metabolic acidosis in acutely ill patients. massive resuscitation. IJntil the safety of hyperchloremic acidosis is We think that until such data are available, the conservative and logical established, it seems prudent to avoid 0.9% saline during massive approach should be to avoid iatrogenic hyperchloremia. This is more

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