Chronobiology of labour pain perception: an observational study

BACKGROUND

Circadian variation may affect many biological and pharmacological phenomena.

METHODS

To assess circadian variations in labour pain perception, 222 consecutive nulliparous women with uncomplicated pregnancy, spontaneous labour, cervical dilatation (3-5 cm), ruptured membranes and normal fetal heart rate tracings were studied. Visual analogue pain scores (VAPS) were analysed and divided into four periods: night (1:01 a.m. to 7:00 a.m.), morning (7:01 a.m. to 1:00 p.m.), afternoon (1:01 p.m. to 7:00 p.m.) and evening (7:01 p.m. to 1:00 a.m.). VAPS were also compared between daytime (morning+afternoon) and nocturnal (evening+night) periods.

RESULTS

Daytime mean VAPS were lower than nocturnal scores [75.6 (15.1) vs 85.7 (14.1), P<0.0001]. VAPS were lower in the morning than in the afternoon, evening and night periods (anova, P<0.0001).

CONCLUSION

Labour pain perception appears to be chronobiological, and this might be taken into account when enrolling parturients in studies designed to assess or treat labour pain.

[Dural puncture in obstetric analgesia. Epidemiologic features and therapeutic management]

OBJECTIVE

To assess the time of occurrence, circumstances and presenting symptoms of unintentional dural puncture (UDP), the location and intensity of postdural puncture headaches (PDPH), and the efficacy of their treatment by epidural blood-patch (EBP).

STUDY DESIGN

Cohort study.

PATIENTS

Cases of UDP recorded over a 4-year period in an obstetric anaesthesia unit.

METHODS

The following variables were studied: maternal age, weight and height, hour of occurrence and number of puncture attempts, existence of reflux of cerebrospinal fluid (CSF) through the needle, experience of the practitioners, subsequent modalities of obstetrical analgesia, frequency of occurrence, clinical characteristics and therapeutic management of PDPH. In case of EBP, the amount of blood and the efficacy of the procedure were also recorded.

RESULTS

Twenty-one patients presented with UDP (0.66%). No reflux of CSF was identified in nine cases. Most UDP occurred at the first or second attempt, usually when performed by a practitioner poorly trained in epidural analgesia in obstetrics. The risk of UDP was higher during night-time work (risk ratio: 3.0; 95% confidence interval: 1.1-8.0; p = 0.04). Subsequent analgesia was provided via the epidural route in 19 cases, subarachnoidal route in one, and intravenous route in one case. PDPH did not develop in two patients. Three patients were given prophylactic EPB, and 16 received curative EBP. A second EBP was required 24 h later in seven patients. One patient developed meralgia paresthetica following EBP.

CONCLUSION

In parturients, UDP usually results in PDPH. A rapid and effective treatment is required, mainly EBP. Another EBP is eventually necessary in some patients.

Intravenous nicardipine for severe hypertension in pre-eclampsia--effects of an acute treatment on mother and foetus

OBJECTIVES

To assess the efficacy in lowering blood pressure, and the safety for mother and foetus of an acute nicardipine therapy in severe pre-eclampsia.

DESIGN

Prospective clinical study.

SETTING

One university hospital obstetric unit.

PATIENTS

Twenty consecutive adult pre-eclamptic patients with severe hypertension.

INTERVENTION

Nicardipine, 1 microgram/kg per min, was given intravenously to lower the mean arterial pressure (MAP) by at least 15%. Then, the dosage was reduced by 1/3, and the final dosage was determined to maintain MAP at 20-30% below the initial value, by increasing or decreasing the infusion rate by 0.5 mg/h.

MEASUREMENTS AND RESULTS

Maternal MAP and heart rate (HR) were assessed every 5 min for 1 h. Foetal HR (FHR) was recorded throughout the study period and assessed for Fischer score. Gestational age, Apgar scores, birth weight, capillary filling time and the duration of stay in the paediatric intensive care unit (ICU) were used to evaluate the short-term perinatal outcome. A 15-30% decrease in MAP occurred within 15-20 min in all patients. An increase in HR was noted, and two patients had severe tachycardia. Maternal side effects included flushing, headache, nausea and dizziness. FHR showed a transient decrease in acceleration episodes and occurrence of decelerations. No nicardipine-related foetal distress occurred. Four infants born during the study period did well at birth and had a good outcome.

CONCLUSIONS

Acute nicardipine therapy can induce severe maternal tachycardia. No severe foetal or neonatal adverse effects occurred. This dose scheme requires comparison with alternative therapeutic options.

Increased risk of unintentional dural puncture in night-time obstetric epidural anesthesia

PURPOSE

To evaluate the experience of the operator and the time of epidural anesthesia as factors contributing to unintentional dural puncture (UDP).

METHODS

In a prospective analysis of recorded cases of UDP the following variables were recorded: maternal height, weight, and weight gain, type of personnel providing epidural analgesia, number of attempts, and hour of the epidural procedure. Work time was divided into day-time (8 AM to 7 PM) and night-time (7 PM to 8 AM), according to the change of coverage of the delivery suite. Night-time was divided into first (7 PM to midnight) and second parts (midnight to 8 AM). Relative risk was used to compare the incidence of UDP among different work-times.

RESULTS

A total of 1489 consecutive epidural procedures were considered. The incidence of dural puncture was 0.8% (12 cases). The relative risk was higher for night-time than day-time (risk ratio 6.33; 95% confidence interval, 1.39 to 28.80; P = 0.006). Seven cases were caused by three operators with poor expertise, and five by two skilled obstetric anesthesiologists.

CONCLUSION

Operator experience and hour of procedure appear to be two important risk factors of UDP The increased risk of UDP in night-work could result from human factors such as fatigue, sleep deprivation or interruption.

[Pressure-controlled mechanical ventilation: a simplified titration method of the extrinsic positive expiratory pressure]

OBJECTIVES

Extrinsic positive end-expiratory pressure (PEEPe) may improve gas distribution within the lungs, induce alveolar recruitment or, conversely, produce pulmonary overdistension, and modify the respiratory impedance. Under pressure-controlled mechanical ventilation (PCV) this phenomenon modifies the minute ventilation and the dynamic compliance of the respiratory system (Crs,dyn). This study was aimed to assess the incidence of a significant gain in Crs,dyn under the effect of PEEPe during PCV.

STUDY DESIGN

Prospective, open, descriptive, case series study.

PATIENTS

Surgical intensive care unit patients, under sedation, neuromuscular blockade and PCV because of severe hypoxaemia (ARDS or acute lung injury).

METHODS

Four incremental levels of PEEPe (4 to 16 cmH2O) of 30 minute duration were applied. Crs,dyn, and PaO2/FIO2 were recorded at the end of each level of PEEPe. The resulting gain in Crs,dyn was calculated and considered as significant if it was greater than the upper limit of confidence (at 99.8%) of the statistical distribution of all the recorded gains.

RESULTS

Thirty patients were included, median and extreme values (within brackets) of PaO2/FIO2 of 117 [53-230] and Crs,dyn without PEEPe of 29 [14.3-46.8] mL.cmH2O-1. Among the 120 recorded gains, a gain in Crs,dyn was found significant at least once in 15 tests of PEEPe out of 30. Within the two groups of patients, the increase in PaO2/FIO2 with incremental PEEPe was similar. The levels of PEEPe producing the greatest increase in Crs,dyn were not correlated with the increase in PaO2/FIO2.

CONCLUSION

In 50% of the studied patients a significant gain in Crs,dyn was found, allowing a less traumatic PCV. These results suggest the clinical usefulness of this method of titration of PEEPe, which requires neither specific devices nor a disconnection of the patient.

Severe preeclampsia superimposed on polyarteritis nodosa

A patient with a history of drug abuse and histologically diagnosed hepatitis B-related polyarteritis nodosa was admitted for severe hypertension. After a cesarean section because of worsening of her clinical status with severe proteinuria and edema, she improved dramatically. No sign of acute polyarteritis nodosa occurred.

[Severe preeclampsia. Principal management modalities before patient transfer]

Preeclampsia is relatively frequent during pregnancy. The occurrence of complications implies referral to a specialized center for optimal care of both mother and fetus. The transfer of these patients is very critical with risk of worsening the mother's status. Management before referral aims to stabilize material clinical status, requiring precise clinical assessment, treatment of severe hypertension or pulmonary edema, and prevention or treatment of eclampsia. The management of oliguria and the tracheal intubation are associated with specific problems. Fetal wellbeing is assessed before and during emergency treatments of maternal disorders.