Production of prostacyclin and thromboxane during cesarean section.

The effect of cesarean section on the production of the antiaggregatory prostacyclin and proaggregatory thromboxane A2 was studied in 12 women by measuring the stable metabolites of prostacyclin and thromboxane A2, 6-ketoprostaglandin F1 alpha and thromboxane B2, respectively, from serial maternal blood samples collected before, during, and after the operation. The plasma 6-keto-prostaglandin F1 alpha concentration was similar to the initial concentrations before the start of anesthesia (mean 121.6 +/- SE 11.5 pg/ml), at the time of skin incision (148.0 +/- 21.0 pg/ml), and at delivery of the infant (136.3 +/- 11.2 pg/ml), but was elevated at the end of the operation (454.8 +/- 56.2 pg/ml) (P less than .001) and one hour later (233.1 +/- 39.5 pg/ml) (P less than .01). These increases were similar whether the patients were operated on under general (N = 6) or epidural (N = 6) anesthesia. The serum thromboxane B2 concentration did not change, indicating no influence of cesarean section on the capacity of the platelets to produce thromboxane B2 during spontaneous clotting. The increased output of prostacyclin may originate from the myometrium and/or intrauterine tissues, which are manipulated during cesarean section. The increased output may play a role in preventing thromboembolic complications during and after cesarean section.

The effect of parturition on umbilical blood plasma levels of norepinephrine.

The norepinephrine concentration in 77 umbilical, arterial, and venous plasma samples, and in 31 simultaneous maternal plasma samples, was measured. The mean (+/- SEM) of 8.7 +/- 1.9 ng/ml in the umbilical artery was higher (P less than .001) than that of 3.6 +/- 0.9 ng/ml in the umbilical vein. In paired fetal-maternal venous samples the norepinephrine concentration of 3.8 +/- 1.7 ng/ml in the fetus was higher (P less than .05) than that of 0.3 +/- 0.1 ng/ml in the mother. Among the different types of vaginal deliveries the umbilical arterial norepinephrine concentrations were: 5.8 +/- 2.1 ng/ml in uncomplicated vaginal deliveries; 16.4 +/- 2.1 ng/ml in breech deliveries (P less than .05 as compared with uncomplicated vaginal deliveries); 8.8 +/- 2.5 ng/ml in vacuum extraction deliveries; and 0.8 +/- 0.3 ng/ml and 11.3 +/- 7.7 ng/ml in twin A and twin B deliveries, respectively. All these values were higher (P less than .001) than those after elective cesarean section, except that for twin A, which was lower (P less than .01) than that for twin B, indicating that labor and vaginal delivery induced activation of the fetal sympathoadrenal system.

The influence of maternal oxygen inhalation on human placental and umbilical venous blood flow.

The effect of maternal short-term inhalation of oxygen (51/min) on intervillous (IVBF) and umbilical vein blood flow (UVBF) was studied in 22 cases during the third trimester of pregnancy. The maternal paO2 levels increased significantly (P less than 0.001) after O2 inhalation. The mean IVBF level was 190 +/- 66 (SD) ml/min per 100 ml of the intervillous space before inhalation and 125 +/- 58 ml afterwards, the decrease being significant (P less than 0.01). UVBF maintained its original level after O2 inhalation. The human fetus seems not to compensate for alterations in oxygen delivery and reduced IVBF after maternal oxygen inhalation, by means of changes in UVBF.

Circulatory changes during and after surgical anesthesia in hypertensive patients treated with clonidine, methyldopa and reserpine.

The cardiovascular changes in 27 hypertensive patients belonging to WHO classes I-II and treated with either clonidine, methyldopa or reserpine during thiopentone-N2O-O2-relaxant-analgesic anesthesia were studied. The variations in systolic and diastolic blood pressure and heart rate during induction of anesthesia and surgery did not differ according to the antihypertensive drug with which the patient was treated. Hypokalemia was found to be the most common postoperative complication in all study groups. The results suggest that the selection of antihypertensive drug does not form a risk factor when hypertensive patients are being prepared for anesthesia and surgery.

Ephedrine and phenylephrine for avoiding maternal hypotension due to spinal anaesthesia for caesarean section. Effects on uteroplacental and fetal haemodynamics.

The effects of i.v. vasopressors on Doppler velocimetry of the maternal uterine and placental arcuate arteries and the fetal umbilical, renal and middle cerebral arteries were studied during spinal anaesthesia in 19 healthy parturients undergoing elective caesarean section. Fetal myocardial function was investigated at the same time by M-mode echocardiography. The patients were randomized into two groups, to be given either ephedrine or phenylephrine as a prophylactic infusion supplemented with minor boluses if systolic arterial pressure decreased by more than 10 mmHg from the control value. Both the vasopressors restored maternal arterial pressure effectively. The ephedrine group showed no significant differences in any of the Doppler velocimetry recordings relative to the baseline values, but during the phenylephrine infusion the blood flow velocity waveform indices for the uterine and placental arcuate arteries increased significantly and vascular resistance decreased significantly in the fetal renal arteries. Healthy fetuses seem to tolerate these changes in uteroplacental circulation well, however, since the Apgar scores for the newborns and the acid-base values in the umbilical cord were within the normal range in both groups. The results suggest that some caution is required when selecting the specific vasopressor agent, the dosage and the mode of administration for the treatment of maternal hypotension secondary to spinal anaesthesia for caesarean section.

The effects of ephedrine and etilefrine on uterine and fetal blood flow and on fetal myocardial function during spinal anaesthesia for caesarean section.

The effects of two vasopressors, ephedrine and etilefrine, on blood flow in maternal uterine, fetal umbilical, middle cerebral and renal arteries and on fetal myocardial function were studied by colour Doppler and M-mode echocardiography techniques during spinal anaesthesia for caesarean section. There were 7 healthy pregnant women in each treatment group. The vascular resistance of maternal uterine arteries increased significantly after both of the vasopressors while the vascular resistance of the umbilical artery remained unchanged. Ephedrine decreased the blood velocity waveform indices in the fetal middle cerebral and renal arteries, increased fetal right ventricular contractility and decreased left ventricular inner end-diastolic dimension. Fetal heart rate was unchanged. Etilefrine caused no detectable changes in fetal haemodynamics or in fetal myocardial function. These findings demonstrate that vasopressors administered for the treatment of minor maternal arterial pressure fall produce vasoconstriction in the uterine circulation during spinal anaesthesia, yet healthy fetuses seem to tolerate these haemodynamic alterations well. On the other hand, ephedrine caused changes in fetal myocardial function and in the vascular resistance of fetal middle cerebral and renal arteries, which demonstrates the potential modifying effect of vasoactive drug given to the mother on fetal haemodynamics.

Uteroplacental haemodynamics during spinal anaesthesia for caesarean section with two types of uterine displacement.

The effects of two types of uterine displacement, on uterine and umbilical artery blood flow waveforms were investigated in 22 healthy parturients undergoing elective caesarean section. Displacement was accomplished with either a wedge under the right hip or a mechanical displacer plus 5 degrees left lateral tilt of the operating table. The first 14 patients were assigned randomly into one of the two displacement methods and the left (underlying) uterine and umbilical artery blood flow waveforms were recorded. In a further 8 patients the displacer was used and flow velocity waveforms for both the right and left uterine arteries and the umbilical artery were recorded. Arterial resistance was expressed in terms of the pulsatility index (PI). There were no significant changes in Doppler velocimetry recordings after preloading in either group, but blood flow velocity waveform indices for the underlying left uterine artery increased significantly (P < 0.001) following spinal anaesthesia when the mechanical device was used. This finding indicates increased vascular resistance in the left uterine artery and is probably due to mechanical compression. A wedge as a method for displacing the gravid uterus seems preferable since its use had no effect on the blood flow indices. The unaltered umbilical artery index values in the groups suggest a great tolerance of minor changes in maternal uterine circulation on the part of the fetus.

Parturients' assessment of water blocks, pethidine, nitrous oxide, paracervical and epidural blocks in labour.

This prospective study evaluated the extent to which the analgesic procedures available resulted in efficient pain relief in 833 Finnish parturients. Their pain ratings were recorded according to their own assessment of pain intensity during labour before and after pain management and according to their total pain experience recalled on the third day after delivery. Only regional blocks significantly diminished pain scores during labour and a striking decrease in pain level (P < 0.0001) was maintained until the second stage by epidural analgesia (EDA) alone. The EDA-group consisted mainly of the primiparous (71%) with induced (17%) and most painful deliveries. After delivery 60% of parturients in this group recalled labour pain as being very severe or intolerable. This was partly due to delays in receiving epidural blockade and partly due to the parturient's reticence in requesting analgesia. Pain relief was rated as excellent or good by 94% of the EDA group but by only 50% of the remaining patients.

The effect of segmental epidural analgesia on maternal growth hormone, insulin, glucose and free fatty acids during labour.

The maternal plasma HGH, insulin, glucose and FFA levels were determined during the course of induced labours in 28 healthy mothers. Every second patient was given segmental epidural analgesia for pain relief during the first stage of labour (epidural) group). The others acted as a control group. HGH did not change significantly during the labour in either group. Insulin decreased during the first stage of labour in both groups. This decrease was more pronounced and statistically almost significant in the control group. Thereafter the insulin increased in both groups. Glucose levels did not change during the first stage, but at the moment of delivery they were significantly higher than the initial levels in both groups. FFA levels became raised in both groups during labour, reaching a peak at the moment of delivery. The results are discussed in relation to stress and effectiveness of pain relief during the first stage of labour.

Maternal and fetal effects of epidural analgesia during labour.

We can state that an effective pain relief during labour, like epidural analgesia, is indicated and it prevents or modifies the pain-induced harmful effects on mother and the fetus. Maternal and fetal ACTH or BE response in labour are not altered, but the increase of maternal cortisol secretion is reduced, thus probably suggesting a lesser maternal stress, to which also point the changes of PRL. Epidural analgesia prevents harmful maternal metabolic changes like hyperventilation, hypocapnia, metabolic acidosis and lactic acid accumulation. These beneficial effects are also reflected in a better fetal and neonatal condition. Carbohydrate and fat metabolism, on the contrary, seem not to be significantly changed by epidural analgesia. Epidural analgesia is beneficial also by reducing the pain induced catecholamine release, and by improving the intervillous blood flow, especially in pre-eclamptic parturients.

The effect of segmental epidural analgesia on maternal and foetal acid-base balance, lactate, serum potassium and creatine phosphokinase during labour.

Maternal and foetal acid-base balance, PaO2, lactate, potassium and creatine phosphokinase (CPK) were studied during the course of 28 induced labours. Every second mother received segmental epidural analgesia during the first stage of labour (epidural group), while the remaining mothers (who were given pethidine for pain relief, if necessary) acted as a control group. In the epidural group the patients had only minimal changes in acid-base balance and lactate concentration during the first stage. During the second stage lactate concentration increased. In the control group, on the other hand, the acid-base balance showed signs of hyperventilation and lactic acid accumulation during the first stage. The potassium changes were quite minimal and were not significantly different between the groups. The CPK level did not change during labour, but 2 and 4 h after delivery it was significantly elevated in both groups. The foetal acid-base balance, potassium, lactate and PaO2 values revealed no differences between the groups at any time. The CPK level in umbilical venous blood was significantly higher in the epidural group.

Subarachnoid block after a "top-up" dose during continuous segmental epidural analgesia in labour. A case report.

We describe a case of spinal block which developed after a second "top-up" of local anaesthetic during segmental epidural analgesia in labour. The incidence of similar cases is reviewed. The importance of aspiration and the injection of a "test" dose before every "top-up" is stressed.

Laryngeal oedema as an obstetric anaesthesia complication: case reports.

Three cases of laryngeal oedema leading to endotracheal intubation difficulties in obstetric anaesthesia are described. The first case occurred immediately postpartum in a patient who developed a swollen face from strenuous bearing down efforts in the second stage of labour. The other two cases were patients with severe preeclampsia including marked generalized oedema. The possibility of the occurrence of laryngeal oedema with resultant endotracheal intubation difficulties in obstetrics should be remembered when endotracheal intubation is considered to avoid the hazard of acid aspiration. The authors prefer the use of regional anaesthetic techniques (if not contraindicated) in obstetrics, and emphasize the use of prophylactic methods to minimize the risk of acid aspiration in connection with general anaesthesia, particularly where endotracheal intubation may be difficult.

The intensity of labor pain in grand multiparas.

BACKGROUND: The purpose of the current study was to investigate differences in pain experiences and requirements for pain control in parturients with different birth experience. Previous studies have shown that the labor pain experience is significantly less intense in multiparas than in primiparas and requirements for analgesic treatment have therefore been assumed to be minimal in this group. METHODS: The pain experience during labor was assessed by 70 consecutive grand multiparas (a minimum of five previous deliveries) compared to that of primiparous (n=70) and II-V parous women (n=70). Pain intensity was repeatedly assessed on a pain intensity scale (0-10) according to the progress of cervical dilatation at the first and second stage of labor. RESULTS: During the latent phase of cervical dilatation (0-3 cm) grand multiparas had a median pain score of 3 compared to 4 in II-V paras and 6 in primiparas (p<0.001). At the end of the first stage and during the second stage the intensity of pain in grand multiparas was significantly higher compared to that in primiparas (median scores 7 to 8 vs 6 to 7, p<0.05). Epidural blocks were administered to 40% of primiparas, 3% of II-V paras and to no grand multiparas (p<0.0001). Twenty-one percent of grand multiparas rated their pain as intolerable (pain scores 9-10) during the second stage compared to 10% of primiparas (p<0.05%). On the third day after delivery, 47% of grand multiparas regarded their analgesia insufficient. CONCLUSIONS: The majority of parturients, including grand multiparas, suffered from intense pain during labor. After delivery, a significant number of grand multiparas felt that they had received insufficient pain relief.