Continuous epidural infusion of ketamine during labour

Abstract

Continuous epidural infusion of ketamine during labourTo the Editor: Naguib et al. reported the successful use of a small epidural dose of ketamine for postoperative analgesia.1 Systemic side effects, motor block, vasoplegia or respiratory depression were not observed. Knowing that ketamine is a safe drug for use during labour, a we decided to evaluate the usefulness of a continuous epidural infusion of ketamine for obstetrical pain relief. Four primiparae, ASA physical status I, requesting pain relief during normal early labour were studied. The study was approved by the University Committee and informed consent was obtained from each patient. In two cases an epidural catheter was inserted at the L3-L4 level. A bolus of 30 mg ketamine hydrochloride in IO ml saline was given, immediately followed by a continuous infusion of 30 mg ketamine/10 ml saline/hour. In the two other cases one catheter was inserted at the L~-L-z level and a second at L,-Ls. A solution of 30 mg ketamine in 3 ml saline was administered through the top catheter, immediately followed by a continuous infusion of 30 mg ketamined3 ml saline/hour. The second catheter was intended for use in the second and third stages of labour. Pain scores were obtained using a linear analogue pain scale. Blood pressure, heart rate and respiratory frequency were monitored.None of the patients reported adequate analgesia at any time during the study. The administration of local anaesthetics was necessary within 45 to 60 minutes, due to insufficient analgesia. Furthermore, all patients complained of blurred vision, felt unpleasant and had mood changes.Although we did not sludy a large number of patients, epidural ketamine does not seem to be appropriate for pain relief during labour. Analgesia appears to be insufficient and is accompanied by undesired systemic side effects which seem to be unrelated to the epidurally infused quantity of ketamine.

The epidural and intrathecal administration of ketamine

“…In 1987, Schneider and Diltoer [63], following the work of Naguib et al [85], decided to assess the effects of the epidural administration of ketamine in six first time mothers. The dose used was 30 mL of ketamine in 10 mL physiologic solution (as a bolus) and then 30 mg of ketamine in 10 mL of normal saline solution per hour continuously administered.…”

“…These are 1) the NMDA recognition site, 2) a glycine or coactivator binding site, 3) a magnesium binding site within the channel, 4) a phencyclidine site within the channel, 5) an inhibitory divalent action site that can bind Zn ++ , 6) a phosphorylation site where protein kinase C and adenosine 3´5´-cyclic monophosphate (cAMP)-dependent protein kinase can modulate the channel function, 7) a redox site, 8) an arachidonic acid site, and 9) a polyamine site. Furthermore, molecular cloning of the genes for the NMDA receptor as well as for the other EAA receptors has revealed that each receptor comprises a number of subunits, and that variability in the way these subunits combine may represent a molecular basis for functional diversity of the receptors [63].…”

Non‐opioid postoperative analgesia

“…Ketamine has also been used as an epidural or intrathecal drug for pain alleviation after surgery. The efficacy of ketamine administered in these ways is controversial, and there are several reports of unpleasant systemic side‐effects ( 96, 97). The neurotoxicity of ketamine is not yet clear, and further animal studies are needed.…”