To the Editor:
We read with interest the study by Brull and Silverman . They have elegantly used videotape analysis to identify the T1-3-induced baseline shift in the thumb position as a mechanism that may explain why visual assessment of the train-of-four ratio (T4/T1) tends to overestimate the measured ratio, i.e., to underestimate the residual fade during recovery from neuromuscular block. In their opinion, their findings help to explain also some other phenomena noted during neuromuscular monitoring.
We think that the findings of Brull and Silverman explain why the use of a spring attached to the thumb (thus preventing the baseline shift) can increase the reliability of clinical assessment of fade as originally suggested by Foldes  and later confirmed by us .
Brull and Silverman conclude their article by stating that "visual assessment alone may be inadequate even in the most experienced hands" and that "other means of assuring adequate neuromuscular recovery should be included."
We certainly agree with them and advocate a more widespread use of this "spring method" as a simple, inexpensive, and fairly effective improvement in clinical assessment of neuromuscular recovery.
T. Tammisto, MD*
K. Wirtavuori, MD dagger
*Department of Anaesthesia and dagger Children's Hospital, Helsinki University Central Hospital, FIN-00290 Helsinki, Finland
K. Linko, MD
The Deaconess Hospital, FIN-00530 Helsinki, Finland
1. Brull SJ, Silverman DG. Real time versus slow-motion train-of-four monitoring: a theory to explain the inaccuracy of visual assessment. Anesth Analg 1995;80:548-51.
2. Foldes FF. Clinical pharmacology and clinical use of muscle relaxants. Anaesthesiol Reanim 1984;9:75-88.
3. Tammisto T, Wirtavuori K, Linko K. Assessment of neuromuscular block: comparison of three clinical methods and evoked electromyography. Eur J Anaesth 1988;5:1-8.