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ARTICLES: Eelco F.M. Wijdicks, Alejandro A. Rabinstein, Edward M. Manno, and John D. Atkinson Pronouncing brain death: Contemporary practice and safety of the apnea test Neurology 2008; 71: 1240-1244 [Abstract] [Full text] [PDF]

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Pronouncing brain death: Contemporary practice and safety of the apnea test

Joseph S. Jeret   (14 December 2008)

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Eelco F.M. Wijdicks   (14 December 2008)

Pronouncing brain death: Contemporary practice and safety of the apnea test 14 December 2008
Joseph S. Jeret, Mercy Medical Center 220 Maple Avenue, Suite 101, Rockville Centre, NY 11570 Send Correspondence to journal: Re: Pronouncing brain death: Contemporary practice and safety of the apnea test BrainsRus2{at}aol.com Joseph S. Jeret	I read with interest the article by Wijdicks et al. describing the need to abort apnea testing in only 3% of patients examined. [1] An additional 7% did not undergo apnea testing due to medical instability as judged by the examining physician although precise criteria and blood pressure cut-offs are not specified. Their description of hemodynamic instability is somewhat unclear: "Hypotension was defined as a new blood pressure decrease to less than 90 mm Hg." This suggests an absolute blood pressure cut-off. The authors then mention that the test "was aborted when progressive hypotension or hypoxemia occurred in the minutes after disconnection," which is vague and suggests some unspecified relative drop in these parameters. Their approach to patients with baseline systolic blood pressure below 90 mm Hg is also not specified. We conducted a large study of apnea testing and used the same technique as Wijdicks et al. We found that 39% of patients developed marked hypotension (defined as at least 15% drop in mean arterial pressure) or need for vasopressor manipulation during the test. [2] Wijdicks et al. do not mention how frequently vasopressors were adjusted during their apnea testing. One difference between the two studies is that all of the patients in the Wijdicks study were on vasopressors or inotropes. In our study, 87% were on inotropes and 42% on vasopressors. We also found that the use of dopamine and vasopressin was not significantly different between the patients with stable blood pressure and hypotension.[2] Wijdicks has previously opined that "hypotension develops during apnea testing in certain patients who otherwise fulfill the clinical criteria of brain death."[3] The most recent study was an opportunity to determine precise guidelines to delineate the significance of the often seen hypotension and guide future apnea testing. Their article does not fully address this. Precise numerical cut-offs are necessary to guide safe performance of apnea testing. References 1. Wijdicks EFM, Rabinstein AA, Manno EM, Atkinson JD. Pronouncing brain death. Contemporary practice and safety of the apnea test. Neurology 2008; 71:1240-1244. 2. Jeret JS, Benjamin JL. Risk of hypotension during apnea testing. Arch Neurol 1994; 51:595-599. 3. Wijdicks EFM. In search of a safe apnea test in brain death: Is the procedure really more dangerous than we think (letter). Arch Neurol 1995; 52:338. Disclosure: The author reports no disclosures.
Reply from the author 14 December 2008
Eelco F.M. Wijdicks, Mayo Clinic College of Medicine, Department of Neurology and Division of Critical Care Neurology 200 First Street SW, Rochester, MN 55905 Send Correspondence to journal: Re: Reply from the author wijde{at}mayo.edu Eelco F.M. Wijdicks	Dr. Jeret urges obtaining precise cut-offs in order to properly conduct safe apnea testing. We are investigating definitive cut-offs yet good predictors are difficult to establish because apnea tests are performed in patients under different circumstances(e.g., polytrauma vs destructive ganglionic hematoma). When hypotension or de-oxygenation occurs, it appears rapidly after disconnection from the ventilator and we have not waited for critical values to appear. The high incidence of hypotension (40%) in Jeret's 1990-1992 study of 70 apnea tests is notable. Strict adherence to preconditions for the apnea test using the 1995 AAN guidelines---and mostly neurointensivists performing the declaration of brain death---may have explained the low incidence of hypotension (7%) in our contemporary study of over 200 patients. Reference 4. Practice parameters for determining brain death in adults (summary statement): report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology 1995;45:1012–1014. Disclosure: The author reports no disclosures.