To the Editor:—

We read with interest the letter by Crites and Ramanathan 1in which they described a case of acute hypoglycemia after combined spinal–epidural analgesia in a parturient with diet-controlled diabetes mellitus.

We were surprised that the authors considered the test dose to be negative. An increase in maternal heart rate of greater than 10 beats/min (in this case, from 110 to 138 beats/min) during a 2-min period after an epinephrine-containing test dose is exactly the criteria Pietro et al.  2used to define a positive result. The signs and symptoms experienced by the patient may have been caused by the inadvertent intravenous injection of lidocaine.

We agree that the onset of effective regional analgesia often is associated with decreases in heart rate and blood pressure reflecting a decrease in maternal catecholamine concentration. 3,4The authors speculate that the sudden reductions in catecholamine and cortisol concentrations was what produced the hypoglycemia. However, they noted no change in the patient’s pulse or blood pressure after combined spinal–epidural analgesia. In our unit, we have used combined spinal–epidural analgesia in more than 11,000 patients and have not yet seen a similar complication.

Finally, we suggest that it is inappropriate to use 5% dextrose to treat severe, symptomatic hypoglycemia. Dextrose at 10% can be infused peripherally, or a higher concentration can be infused centrally. 5 

Crites J, Ramanathan J: Acute hypoglycemia following combined spinal-epidural anesthesia (CSE) in a parturient with diabetes mellitus. A nesthesiology 2000; 93: 591–2
Pietro C-R, Lingaraju N: Tests to evaluate intravenous placement of epidural catheters in labouring women: A prospective clinical study. Anesth Analg 1998; 86: 985–8
Cascio M, Pygon B, Bernett C, Ramanathan S: Labour analgesia with intrathecal fentanyl decreases maternal stress. Can J Anaesth 1997; 44: 605–9
Shenan A, Cooke V, Llyod-Jones F, Morgam BM, De Swiet M: Blood pressure changes during labour and whilst ambulating with combined spinal epidural analgesia. Br J Obstet Gynaecol, 1995; 102: 192–7
British National Formulary, 40th edition. British Medical Association, Royal Pharmaceutical Society of Great Britain, 2000, pp 325