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Biomedical subjects

B Hanson

Publications and source records attributed to B Hanson.

At least 73 records · Page 4Linked to original sources
PubMed1979

Continuous mini-infusion of bupivacaine into the epidural space during labor. Part I: Radiographic visualization of the epidural catheters.

Two groups, each consisting of 20 parturients, were given a continuous infusion of 0.25 per cent bupivacaine into the epidural space for pain relief, after test and loading doses. The analgesic effect was registered during labor. After delivery the course of the catheters in the epidural space was investigated radiologically. In the first group long catheters (mean 16.5 cm from the skin surface) and in the second group short catheters (mean 10.5 cm) were used. The medial approach in the epidural space was varied between the first and second lumbar interspaces. The relationship between the position of the catheter tip and the degree of analgesia was also studied. In two mothers with fetus mortuus ante partum, the spread of a radiopaque dye solution was followed during labor. Through the force of gravity and the mothers position, the spread of solution covered three segments within 30 minutes. It was concluded, that slow infusion of local anesthetic solution gives satisfactory pain relief if the catheter is inserted into the first lumbar interspace to a depth of 10--12 cm from the skin surface ending close to the Th12 level. Gradual raising of the mother from the supine to the semirecumbent position and regular change of sides during mini-infusion is important for an even spread of the analgesic solution and analgasia.

Anesthesia, Epidural↗
PubMed1979

Continuous mini-infusion of bupivacaine into the epidural space during labor. Part II: Blood concentration of bupivacaine.

Mini-infusion of 0.25 per cent bupivacaine plain into the epidural space was used in 16 healthy women for pain relief during labor. After a loading dose, continuous administration was ensured by using an automatic pump at an infusion rate of 5 or 8 ml per hour. Maternal venous blood concentrations of bupivacaine were determined 20, 40, and 60 minutes after the loading dose. Further samples were taken hourly until delivery. Fetal blood concentrations were determined from fetal scalp blood during mini-infusion, and from umbilical venous blood at delivery. Maternal blood levels averaged 206 ng/ml. The maximum concentration (604 ng/ml) did not exceed 30 per cent of the toxic level. The blood concentration of bupivacaine did not tend to increase during the course of continuous infusion. Tachyphylaxis could not be detected statistically. The fetal blood concentration during blockade averaged 58 ng/ml, giving a feto-maternal ratio of 0.28. The neonatal-maternal ratio, calculated from the umbilical venous blood, was 0.32. With a shift of the acid-base status towards acidosis in the neonate, the ration of bupivacaine slightly increased. Absence of maternal hypotension as well as absence of fetal heart irregularities during infusion may be attributed to the low and stable blood concentration of bupivacaine. The mean Apgar score was 9.5 at one minute and 9.9 at five minutes. The maternal arterial acid-base balance at delivery was normal. The fetal acid-base status at delivery showed wide variation, without any relation to the Apgar score or the total dose of bupivacaine. It is concluded that continuous mini-infusion of bupivacaine by means of an automatic pump has advantages over intermittent administration.

Anesthesia, Epidural↗
PubMed1979

Continuous mini-infusion of bupivacaine into the epidural space during labor. Part III: A clinical study of 225 patients.

Obstetric analgesia was accomplished by segmental continuous blockade in 225 women. The technique involved automatic pump infusion of 0.25 per cent bupivacaine solution into the epidural space at a rate of 5 ml per hour after initial doses of 2 and 5 ml bupivacaine. If the analgesia was insufficient one or two single injections of 5 ml of bupivacaine were added. Statistical evaluation of the results could be carried out for 218 women, 158 of whom were nulliparae and 60 multiparae. Fully satisfactory analgesia was achieved in 96 per cent of the nulliparae and 88 per cent of the multiparae in the first stage of labor. In the second stage of labor 46 per cent of the mothers were given pudendal blockade to maintain statisfactory analgesia. The positioning of the patient in the first stage of labor from supine to semirecumbent was of importance to spread the analgesic agent caudally, to the sacral nerve roots, and to control the pain due to stretching of the vagina and perineum. In the total material 17 per cent of the neonates were delivered by vacuum extraction. When the infusion into the epidural space was started in early labor, the incidence of vacuum extraction was 9 per cent, as compared with 38 per cent when it was started at 6 cm cervical dilatation or later (p less than 0.01). 9.8 per cent of the neonates were delivered by cesarean section. Fetal head malposition occurred in 8.7 per cent. A drop in blood pressure was noted in 7 per cent of the women. The condition of the newborn was unaffected by the analgesia. The mini-infusion system minimized the risk for infection. The danger in case of accidental intravascular injection was reduced, due to slowly administered bupivacaine. At the maternity department this technique has created a positive attitude towards epidural blockade, as midwives and doctors have found it safe and easy.

Anesthesia, Epidural↗
PubMed1978

Fatal Rocky Mountain spotted fever.

Forty-four fatal cases of Rocky Mountain spotted fever (RMSF) occurring in 1974 were compared with 50 nonfatal cases of similar age, sex, date of onset, and place of occurrence. Diagnosis and initiation of treatment in fatal cases were substantially delayed compared with nonfatal cases. Several reasons for this delay were identified: (1) the rash appeared later in the course of illness in the fatal cases, often not until the patient was terminal, (2) a history of tick bite was less often obtained during life or obtained late in the clinical course in fatal cases, and (3) initial nonspecific symptoms or unexpected symptoms led to an initial diagnosis of more common diseases. Only two fatal cases were treated with either tetracycline or chloramphenicol before the sixth day of illness. Presumptive diagnosis of RMSF and initiation of tetracycline therapy before onset of rash may be necessary to reduce mortality.

Adolescent↗