i

CORRESPONDENCE

ETHYLENE GLYCOL POISONING To the Editor: Palmer et al (Am J Med 1989; 87: 91-92) recently described cranial nerve deficit as a clue to the diagnosis of ethylene glycol toxicity, and reviewed the differential diagnosis of anuric acute renal failure. I would call attention to two pertinent observations, in addition to the excellent discussion provided by the authors, First, clinicians should be aware that a small percentage of cases of acute tubular necrosis (ATN) will present with anuria. Since ATN occurs far more commonly than the other disorders that lead to anuric acute renal failure, this atypical presentation will still contribute significantly to the overall incidence of anuria. The reference cited by the authors in their review of the differential diagnosis includes ATN [I]; in fact, Dr. Narins emphasizes this point in his teaching. Second, I recommend the practice of irrigating the urinary bladder with 50 to 100 mL of saline, centrifuging the irrigant, and examining the sediment for calcium oxalate crystals when examining an anuric patient who may have ingested toxins. This approach permits at least a qualitative “urinalysis” in the case of a patient who is producing no urine. It also increases the chance of detecting crystalluria in any given patient with ethylene glycol poisoning, for, in my experience, as well as in the cases described by Palmer et al, the classic observation of massive crystalluria [2] may be lacking. In one instance I found several calcium oxalate crystals in the bladder washings from a comatose, anuric patient with an elevated anion gap who proved to have ingested a lethal dose of ethylene glycol. This enabled immediate institution of specific (albeit ultimately unsuccessful) therapy. Thousand

DAVID A. GOODKIN, M.D. Oaks, California 91360

1. Rudnick MR, Basti CP, Elfinbein IB. Narins RG: The differential diagnosis of acute renal failure. In: Brenner BM, Lazarus MJ, eds. Acute renal failure. Phlladelphia: WB Saunders, 1983; 176-222. 2. Parry MF. Wallach R: Ethylene glycol poisoning. Am J Med 1974; 57: 143-150. Submitted

September

8. 1989. and accepted October 2, 1989

84), “clinical determination of futility is ambiguous because estimates of treatment success are clouded by disagreements of language, statistical uncertainty, and To the Editor: George et al (Am J Med 1989; 87: social prejudices.” Obviously, if mortality is considered the end28-34) suggest a pre-arrest morbidity (PAM) index for predicting point, CPR is futile if there is no the likelihood of survival after car- chance of survival. We agree with diopulmonary resuscitation Dr. Burnside that severity of illness (CPR). The notion, I gather, is that scales, such as the PAM Index, will undoubtedly not identify a subset if we could predict who will survive CPR and who will not, we could that has a “zero” likelihood of surof then avoid the effort, cost, and pos- vival. However, identification sible family anguish caused by a futhose patients who have an extile effort. tremely Zow likelihood of survival is helpful. For some patients, resusciHow accurate should such a predictor be? The authors numeritation attempts under circumcally expressed the PAM Index at stances of such low probability a level for which there were no sur- may not be in the best interest of the patient and/or the patient’s vivors, which is certainly acceptably stringent. Or is it? Were the family. The “accuracy” of the PAM InPAM Index to be widely adopted, of course the predictability would dex is obviously subject to question be constant. There would be no and we do not propose that PAM survivors since there would be no scoring be the sole determinant in attempts. Similarly, there would “do-not-resuscitate” decisions. also be no improvement in the fu“Quality” issues-the “clinical ture. The authors take refuge in judgment” and experience of rebetter statistics: “. . . if patients in sponsible physicians and multiple our series with a PAM score greater social issues-will clearly continue than 8 (n = 24) had not received to impact significantly on the deciCPR, the short-term survival rate sion process. Our study (Am J Med would have been 30% (34 of 116) 1989; 87: 28-34) demonstrates that with no change in hospital mortalia multivariate approach such as ty.” the PAM Index improves evaluation of the probability of survival in The adoption of this model would also imply that there is no patients who are at risk for cardiac arrest and is a useful additional value to an unsuccessful CPR. Might there not be value to the tool in this complicated decision staff, almost always residents who process. are learning? Might there not be Death is an inevitable process for value to some families who yearn to us all. Although physicians ultiknow that “everything possible was mately cannot prevent death, done”? Might there not also be the hopefully we can improve our abilivalue of the unprecedented survi- ty to recognize impending mortality and turn our efforts toward provor whose successful resuscitation yields some clue to improving the viding succor for patients and their technique? families in their final hours. By so JOHN W. BURNSIDE, M.D. doing, we can greatly ease the financial and emotional burdens University of Texas Southwestern Medical School that we otherwise place on patients Dallas, Texas and their families who put their trust in us. SubmItted July 28, 1989, and accepted October 24,

PREmARRESTMORBIDITY INDEX IN PREDICTION OF SURVIVAL AFTER CARDIOPULMONARY RESUSCITATION

1989

The Reply: Dr. Burnside’s question-At what apparent probability should a therapy be considered futile?-is clearly essential in clinical decisionmaking. As recently stated by Lantos et al (Am J Med 1989; 87: 81February

1990

The American

W. BARTON CAMPBELL, M.D. ALFRED L. GEORGE, Jr., M.D. BENJAMIN P. FOLK, III, M.D. PAMELA L. CRECELIUS, R.N. Saint Thomas Hospital Nashville, Tennessee Journal

of Medicine

Volume

88

201