Shiro Oku

Comparison of the in vitro caffeine-halothane contracture test with the Ca-induced Ca release rate test in patients suspected of having malignant hyperthermia susceptibility.

AbstractPurpose. We compared the results of the in vitro caffeine-halothane contracture test (CHCT) according to the protocols of the North American Malignant Hyperthermia Group (NAMHG) and the European Malignant Hyperthermia Group (EMHG) with the Ca-induced Ca release (CICR) rate test in the same patients with suspected malignant hyper thermia (MH). Methods. Five normal controls and 16 patients suspected of having MH susceptibility were studied. Muscle biopsies were usually obtained from the musculus vastus lateralis. Diagnostic cutoff points and procedures for CHCT protocols were as described in the original and renewal versions of NAMHG and EMHGs. The CICR rate test was performed according to the protocol reported by Endo et al. Results. All five normal controls and two patients with abortive MH, two with postoperative hyperthermia, and three with high serum creatine kinase levels were normal in the three tests. Three patients with MH reactions and one patient with a history of masseter spasm were classified as MH positive according to NAMHG criteria and MH susceptible and MH equivocal according to EMHG criteria. There were five cases with discordant results between the CHCT and CICR rate tests. Conclusion. We propose that muscle biopsy for diagnosis of MH susceptibility should combine the CHCT with the CICR rate test, which may identify the defective site of Ca release channels.

A new leak test for specifying malfunctions in the exhalation and inhalation check valve.

problem exists that there is fractional extraction of epinephrine in forearm tissues in the range of 25%-50% (1,2). Measurement of norepinephrine concentrations from the antecubital vein is also subject to the influence of local factors that both add and remove norepinephrine from forearm tissues. Accordingly, we acknowledge that the pulmonary artery is the best sampling site for measuring epinephrine concentrations.and that arterial measurements provide a good alternative. However, the medical condition of our patient population did not ethically justify the use of either pulmonary or radial arterial catheters, so antecubital venous sampling was used instead. In taking this limitation into consideration, we wish to emphasize that we evaluated the percentage of change of both epinephrine and norepinephrine concentrations in response to a standardized stimulus (tracheal intubation) and measured the within-patient serial changes of both catecholamines over a very short period ( 4 0 min). We observed that the changes in catecholamine concentrations paralleled the cardiovascular response in both the control and experimental groups, suggesting a reasonably reliable reflection of the body‘s response to stress. Reflecting on our study design, we concur with the recently expressed opinion of Dr. Herd that “epinephrine is not secreted from organs other than the adrenal medulla. Accordingly, few assumptions need to be made concerning the pattern of epinephrine levels in the forearm venous blood” (1). Donald R. Miller, MD Raymond J. Martineau, MD Kathryn Hull, RN Department of Anaesthesia