The febrile parturient: choice of anesthesia

Krzysztof M Kuczkowski
2002 Southern African Journal of Anaesthesia and Analgesia  
The febrile parturient: choice of anesthesia ture and temperature control mechanisms that constantly adjust body temperature, to maintain this level. Fever is defined as an increase in core body temperature above 38 ºC, which is secondary to an increase in the hypothalamic set point. 1, 3 The human body temperature rarely exceeds 41ºC. Normal circadian fluctuation in body temperature with increase in the evening and decrease in the morning continues even in febrile patients. 4 Under normal
more » ... 4 Under normal circumstances, core body temperature is tightly regulated, with a variation of approximately 0.5ºC. While it is uncertain as to the benefits of fever, there are suggestions that the increased body temperature aids in the activation of the host immune response with augmentation of bactericidal, phagocytic and chemotactic properties of polymorphonuclear leukocytes. The negative aspects of fever include increased basal metabolic rate and increased cardiac demand. FEVER: INTERACTION WITH PREGNANCY Physiologic changes of pregnancy include an increase in the maternal basal metabolic rate. 5 Maternal body temperature in labor is also significantly affected by the degree of physical activity and intensity of uterine contractions. Pain associ- INTRODUCTION Fever is a common clinical problem in labor and delivery suites -worldwide. The febrile parturient presents a unique diagnostic dilemma and therapeutic challenge to both an obstetrician and an anesthesiologist involved in her care. Fever can result from a variety of infectious microorganisms, tissue trauma, malignancy, drug administration, endocrine and immunological disorders. However, infection is by far the most common cause of fever in the parturient. 1, 2 The infectious etiology of fever in a parturient may be pregnancy specific, such as chorioamnionitis, or not specific to pregnancy, such as urinary tract infection. The risk to the mother and the fetus is significantly increased in pregnancy complicated by infection and fever. The diverse clinical manifestations of various infectious disorders combined with the unique anesthetic implications of pregnancy may result in life-threatening complications and significantly impact upon the practice of obstetric anesthesia. The diagnosis of infection in pregnancy often raises questions about the safety of neuraxial anesthesia in febrile patients. Despite this concern, and lack of universal guidelines, it has now been well established that the presence of infection and fever in labor does not always contraindicate the administration of regional anesthesia. 2 The decision whether to administer regional anesthesia or not in a febrile parturient should be based on an individual risk-to-benefit ratio. FEVER: DEFINITION AND PATHOPHYSIOLOGY In humans normal body function depends on a relatively constant body temperature, which is regulated by hypothalamus. The balance between heat production and heat loss to the environment determines human body temperature. 3 The core temperature is usually 0.5 ºC higher than the oral temperature. There is a circadian fluctuation in temperature with the nadir at 6 a.m. and the peak at 8 p.m. In females there is a monthly cycle, in which the temperature increases at the time of ovulation and falls back to baseline at the onset of menstruation. The normal core body temperature in adults ranges from 36 to 38 ºC. 3 The human body has a set point tempera-
doi:10.1080/22201173.2002.10872979 fatcat:gbf6gusx75d7dfheqvtyonmtd4