Effect of Diabetes Mellitus on Spinal Block Criteria During Cesarean Section

Regional anaesthetic techniques are now the most frequently used type of anaesthetic used for caesarean deliveries. They have a better safety profile than general anaesthesia in the pregnant woman. The choice of whether to use a spinal, epidural or combined spinal-epidural technique will depend on patient and surgical factors.

Although spinal (subarachnoid or intrathecal) anaesthesia is generally regarded as one of the most reliable types of regional block methods, the possibility of failure has long been recognized.

Most experienced practitioners would consider the incidence of failure with spinal anaesthesia to be extremely low, perhaps less than 1%. However, a figure as high as 17% has been quoted from an American teaching hospital, yet most of the failures were judged to be 'avoidable Spinal anaesthesia (SA) is a frequently used anaesthetic technique, and success rates and patient satisfaction are generally high. However, there are numerous reports of failed SA (FSA), and published failure rates in large series of SA range from 0.46% to 17%. The reasons most commonly provided to explain failure are technical problems, errors of judgement with respect to pharmacological factors, such as inadequate dose of local anaesthetic (LA), and inadequate positioning of the patient. . Proposed mechanisms for inadequate block despite correct dosing and injection technique are maldistribution , variability in the anatomy of the lumbar subarachnoid space, inadvertent subdural or epidural injection, and resistance to the effects of LA.

Successful spinal anaesthesia requires the deposition of the correct dose of the correct drug in the CSF that is in free continuity with the spinal cord and cauda equina, and that there are no barriers, either physiological, biochemical or mechanical, to prevent the normal anticipated action of the drug in the spinal cord. Gestational diabetes mellitus (GDM) refers to any degree of glucose intolerance with onset or first recognition during pregnancy. It occurs in 2-9% of all pregnancies and accounts for 90% of cases of diabetes mellitus complicating pregnancy. A1C is routinely measured approximately every 3 months in individuals with diabetes to assess the mean glucose concentration. The erythrocyte life span is ∼120 days. Thus, the 3-month interval between tests of A1C reflects the mean blood glucose over the preceding weeks to months. Hence, the rate of change of A1C in pregnancy reflects the glycemic control over the past few weeks Hoppe et al. declared diabetes mellitus (DM)as a possible cause of SA failure in a case series consisting four obstetric patients.

two possible factors may be important for quality and level of SA inpatients with DM. First is neuropathy and second is possible changes in composition of CSF such as density or volume secondary to hyperglicemia in blood and CSF .So the investigators hypothesized that DM could affect the success of SA