The Lancet September 24, 2005; v. 366, n. 9491, pp. 1073-1074

The Lancet September 24, 2005; v. 366, n. 9491, pp. 1073-1074

Mark JS Heath a , Donald R Stanski b and Derrick J Pounder c

Using post-mortem blood samples taken as many as 2 days after death, Leonidas Koniaris and colleagues1 conclude that 43% of inmates undergoing lethal injection with 2 g intravenous thiopental had blood thiopental concentrations consistent with awareness.

Koniaris and colleagues do not present scientifically convincing data to justify their conclusion that so large a proportion of inmates have experienced awareness during lethal injection. Indeed, published and unpublished data, and clinical experience, contradict their conclusions.

It is widely accepted that concentrations of a drug in post-mortem blood might not reflect the concentrations present at the time of death because of post-mortem drug redistribution—ie, site-dependent and time-dependent changes in drug concentration that occur after death.2

These problems are particularly significant with thiopental, a highly lipophilic drug. Thiopental can take many minutes to reach equilibrium in highly perfused compartments, and longer in less well perfused tissues.3 When death ensues before equilibrium, as is the case during lethal injection, post-mortem passive diffusion from blood into tissues can cause thiopental concentrations in blood to decline. Results of studies on post-mortem drug diffusion effects suggest that this is a likely explanation for low concentrations of thiopental in blood sampled several hours to days after death. The absence of samples drawn in the first hours after death, the use of samples drawn from different anatomical sites, and the failure to characterise accurately the time between death and blood-drawing probably contributed to Koniaris and colleagues' flawed conclusions. Notably, Koniaris and colleagues have retracted three critical data points and recognise that they incorrectly estimated the times between autopsy and blood sampling in numerous cases (T Zimmers, written communications), eroding support for their statement that “[t]hiopental concentrations did not fall with increased time between execution and blood sample collection.” Our ongoing analysis of 45 lethal injections from Oklahoma, including 18 data points in which blood sampling occurred within 100 min of death, shows a rapid and time-dependent decline in thiopental concentrations, underscoring the pitfalls of neglecting post-mortem redistribution.

There are other flaws in the paper. Clinical studies have shown that 2 g thiopental, if effectively delivered, creates unconsciousness for longer than 10 min.4 Koniaris and colleagues have not provided an adequate description of how they defined thiopental blood concentrations that allow consciousness using publications by one of us (DRS).

They have, however, correctly reflected on well recognised technical issues that increase the risk of consciousness during lethal injection. These problems include, but are not limited to: unqualified individuals charged with achieving venous access, poor supervision of intravenous drug delivery systems, poor control over timing and sequence of drug delivery, and inclusion of drugs that are unnecessarily dangerous when given by unqualified people in an execution setting. These problems are completely avoidable and warrant, indeed demand, rectification.5

Post-mortem thiopental concentrations from blood drawn shortly after death can be quantitatively reliable and, in conjunction with autopsy and witness data, can provide evidence of a prisoner's potential risk of consciousness. Unfortunately, the data provided by Koniaris and colleagues do not support the conclusion that 43% of inmates undergoing lethal injection are at risk of awareness.

All authors have agreed to offer expert advice to the Oklahoma Federal Public Defender regarding lethal injection.

References

1. Koniaris L, Zimmers TA, Lubarsky DA, Sheldon JP. Inadequate anaesthesia in lethal injection for execution. Lancet 2005; 365: 1412-1414. Abstract | Full Text | Full-Text PDF (66 KB) | CrossRef

2. Pounder DJ. The nightmare of postmortem drug changes In: , Wecht CH, ed. Legal medicine. Salem: Buttersworth, 1993: 163-191.

3. Price HL. The uptake of thiopental by body tissues and its relation to the duration of narcosis. Clin Pharmacol Ther 1960; 1: 16-22.

4. Brodie B, Lester M, Papper P, et al. The fate of thiopental in man and a method for its estimation in biological material. J Pharmacol Exper Ther 1950; 98: 85-96.

5. Royal Commission on Capital Punishment. In: Royal Commission on Capital Punishment 1949–1953: report. London: HMSO, 1953: 257-261
http://www.bopcris.ac.uk/bopall/ref9738.html
(accessed Aug 8, 2005).

Affiliations

a. Department of Anesthesiology, Columbia University, 630 West 168th St, New York, NY 10032, USA Dr. Heath – mail: mh22@columbia.edu

b. Stanford University School of Medicine, Stanford, CA, USA
c. University of Dundee, Dundee, UK