Pulmonary oedema associated with beta 2-sympathomimetic treatment of premature labour

Betamethasone use and risk factors for pulmonary edema during the perinatal period: a single-center retrospective cohort study in Japan

Background

A few studies have reported that maternal administration of antenatal corticosteroids increased the risk of pulmonary edema (PE). However, despite the increasing usage rate of betamethasone as antenatal corticosteroid, maternal administration of betamethasone as a risk factor for PE has not been well studied. This study aimed to evaluate how maternal backgrounds and complications, tocolytic agents, and betamethasone affect the incidence of PE during the perinatal period and determine the risk factor for PE.

Methods

This was a single-center retrospective cohort study in Kurashiki, Japan. The study subjects were patients who had been admitted to our hospital for perinatal management including pregnancy, delivery and puerperium between 2017 and 2020. The primary outcome measure was defined as the incidence of PE during hospitalization. First, in all study subjects, Cox proportional hazards model was used to determine the risk factor for PE during the perinatal period. Next, using propensity score matching, we divided the patients into the betamethasone and betamethasone-free groups and examined the association between betamethasone use and the incidence of PE with Cox proportional hazards model.

Results

During the study period, 4919 cases were hospitalized, and there were 16 PE cases (0.3%). In all analyzed subjects, the occurrence of PE was significantly associated with preeclampsia (hazard ratio 16.8, 95% confidence intervals (CI) 5.39–52.7, P < 0.001) and the combined use of the tocolytic agents such as ritodrine hydrochloride and magnesium sulfate, and betamethasone (hazard ratio 11.3, 95% CI 2.66–48.1, P = 0.001). In contrast, after propensity score matching, no statistically significant difference was found between the betamethasone and betamethasone-free groups in the incidence of PE (hazard ratio 3.19, 95% CI 0.67–15.3, P = 0.145).

Conclusions

A combined use of tocolytic agents and antenatal corticosteroids such as betamethasone may be an independent risk factor for PE during the perinatal period. On the other hand, betamethasone use alone may not be associated with the incidence of PE. When tocolytic agents and betamethasone are administrated to pregnant women, it is important to pay attention to the appearance of maternal respiratory symptoms.

Association between total dose of ritodrine hydrochloride and pulmonary oedema in twin pregnancy: a retrospective cohort study in Japan

OBJECTIVE

Pulmonary oedema is recognised as a severe side effect of ritodrine hydrochloride. Recently, the number of twin pregnancies has been increasing. Few studies have reported the association between total dose of ritodrine hydrochloride prior to delivery and pulmonary oedema in twin pregnancy. We aimed to examine this association and determine the optimal cut-off threshold of total ritodrine hydrochloride dose to predict the incidence of pulmonary oedema in twin pregnancy based on obstetric records.

DESIGN

Retrospective cohort study.

SETTING

Yamanashi Prefectural Central Hospital, Japan.

PARTICIPANTS

Two hundred and twenty-six women with twin pregnancy who delivered at Yamanashi Prefectural Central Hospital between September 2009 and November 2016.

METHODS

The obstetric records of the participants were analysed. We defined 1 unit of ritodrine hydrochloride as 72 mg per 24 hours continuous transfusion at 50 µg/min to calculate the dose of ritodrine used for tocolysis.

OUTCOME MEASURES

Multivariable logistic regression analysis was performed to examine the association between total dose of ritodrine hydrochloride used for threatened preterm labour and pulmonary oedema, while controlling for potential confounding factors. Then, a receiver-operating characteristic curve was used to determine the optimal cut-off of total ritodrine dose to predict pulmonary oedema incidence.

RESULTS

Mean maternal age was 32 (range, 18-46) years; 143 participants were nulliparous (63.3%), 109 had (48.2%) term deliveries and 194 (85.8%) had caesarean deliveries. The overall incidence of pulmonary oedema was 13.7% (31/226). Multivariable analysis showed that the total dose of ritodrine was significantly associated with pulmonary oedema (adjusted OR 1.02; 95% CI 1.004 to 1.03). The best cut-off point to predict the incidence of pulmonary oedema was 26 units (1872 mg) (sensitivity, 61.3%; specificity, 87.8%).

CONCLUSION

Our results suggest that consideration of the total dose of ritodrine hydrochloride is helpful in the management of patients with threatened preterm labour in twin pregnancy.

Risk factors for pulmonary edema in triplet pregnancies

OBJECTIVE

Multiple gestations are known to be at increased risk for pulmonary edema. Our objective was to characterize this morbidity in a cohort of triplet pregnancies.

STUDY DESIGN

Charts from triplet pregnancies managed by the Georgetown University Hospital Maternal-Fetal Medicine service were abstracted for demographic information and complications. Cases who developed pulmonary edema were compared with those who did not using Fisher exact test, chi(2) and Student's t-test with p <0.05 considered significant.

RESULTS

Of 66 triplet pregnancies with complete records, 15 (22.7%) were complicated by pulmonary edema. Patients developing this condition were more likely to be receiving magnesium sulfate therapy than those who did not [14/15 (93.3%) vs 32/51 (62.7%) p=0.049]. There was no difference between patients developing pulmonary edema and those who did not in terms of maternal age (mean+/-SD: 34.5+/-6.8 vs 34+/-4.3 years, p=0.8) or gestational age at delivery (33.3+/-2.3 vs 32.8+/-3.5 weeks, p=0.6), but the former group had smaller babies than the latter (1739+/- 369 vs 1891+/-538 g, p=0.04). Among the patients treated with magnesium sulfate, those who developed the more severe form of pulmonary edema were more likely than those who did not to have been treated for pre-eclampsia than preterm labor (6/10 (60%) vs 7/33 (21.2%), p=0.04).

CONCLUSIONS

Pulmonary edema is a common complication of triplet pregnancy. Patients receiving magnesium sulfate, having pre-eclampsia or fetal growth restriction are at increased risk for pulmonary edema, particularly in its worst clinical presentation.

A randomized comparison of nifedipine and ritodrine for suppression of preterm labor

OBJECTIVES

To compare the efficacy and safety of nifedipine and ritodrine in preventing preterm labor, and to evaluate maternal side effects and neonatal outcome.

STUDY DESIGN

Non-blind, randomized controlled trial

RESULTS

A randomized trial of 102 pregnant women with gestational ages under 34 weeks, including 24 with twin pregnancies and 45 on betasympathicomimetic drugs, who had regular uterine contractions with either observed cervical changes or preterm rupture of membranes. After stratification women were randomly assigned to receive either ritodrine intravenously or nifedipine orally. Fifty-five women were randomized to the nifedipine group and 47 to the ritodrine group. As expected, both groups were comparable in terms of several entry variables, including mean gestational age, ruptured membranes, treatment with tocolytic drugs, cervical examination, contraction frequency, age, and twin gestation. Delivery of women in the nifedipine group was delayed for 48 h, 7 days, and until 34 weeks gestation in 33 (60%), 26 (47%) and 21(38%) cases, respectively, compared with 31 (66%), 21(45%) and 11(23%) women in the ritodrine group (no significant difference). Maternal side effects were significantly less common in the nifedipine group than in the ritodrine group, however after 7 days of therapy there was no difference between the two groups. Neonatal outcome was similar in the two groups, with four neonatal deaths in the nifedipine and five in the ritodrine group.

CONCLUSIONS

Nifedipine seems to be as effective as ritodrine in the treatment of preterm labor and is associated with less frequent side effects.

Acute, reversible left ventricular dysfunction in status asthmaticus

Three cases of rapidly reversible severe myocardial depression are described in patients with status asthmaticus. Initial echocardiograms obtained within 1 day of hospital admission revealed global left ventricular hypokinesis with ejection fractions of 11 to 34%. Follow-up echocardiograms obtained only 3 to 8 days later revealed marked improvement of left ventricular function. Possible mechanisms responsible for the observed rapidly reversible myocardial depression and the clinical implications of this finding are discussed.

Evaluation of maternal fluid dynamics during tocolytic therapy with ritodrine hydrochloride and magnesium sulfate

OBJECTIVE

The purpose of the study was to observe and compare the effects of ritodrine hydrochloride and magnesium sulfate on maternal fluid dynamics.

STUDY DESIGN

Fourteen women in preterm labor were prospectively studied during tocolytic therapy with either ritodrine hydrochloride or magnesium sulfate. The cardiovascular and renal effects of a pretreatment crystalloid infusion were compared with those observed during tocolytic therapy. Profile analysis and repeated measures of variance were used to analyze the data.

RESULTS

Ritodrine hydrochloride was associated with decreased colloid osmotic pressure, hematocrit, and serum proteins and increased maternal and fetal heart rates. Arginine vasopressin levels increased during the first 2 hours of therapy, then returned to baseline. Sodium excretion was reduced and there was marked fluid retention. Intravenous magnesium sulfate also resulted in a reduction of colloid osmotic pressure, but hematocrit, serum protein concentration, arginine vasopressin, maternal and fetal heart rates, and mean arterial pressure were minimally affected. Sodium excretion increased to a maximum at 6 to 8 hours of treatment, then returned to baseline. A positive fluid balance was also noted in magnesium sulfate-treated patients but to a lesser degree than with ritodrine.

CONCLUSIONS

Sodium retention appears to be the primary cause of plasma volume expansion in ritodrine-treated patients, whereas volume expansion during magnesium sulfate therapy is probably related to intravenous overhydration. In the absence of risk factors for pulmonary capillary membrane injury, available evidence supports volume overload as the principal mechanism for pulmonary edema during tocolytic therapy.

The actions of tulobuterol on isolated preparations of gravid human myometrium

1. The effects of tulobuterol (Abbott 54173) on the contractile force developed by electrically stimulated strips of gravid (gestation 36-40 weeks) human uterine muscle were compared with those of isoprenaline and adrenalin. 2. Isoprenaline produced inhibition of electrically evoked contractions of myometrium from 12 of 17 women at concentrations at or below 1 mumol/L (range 0.001-1 mumol/L). It enhanced contractions at concentrations of 10-50 mumol/L. In tissues from the remaining five women isoprenaline produced neither inhibitory nor excitatory effects. Adrenalin (0.1-50 mumol/L) was found to enhance contractile force in a concentration-dependent manner (EC50 = 0.30 mumol/L). 3. In the presence of metoprolol (0.3 mumol/L), a selective antagonist at beta 1-adrenoceptors, the isoprenaline concentration-response relationship was shifted to the left, indicating that beta 1-adrenoceptors are present and that they mediate excitation in the human uterus. 4. In contrast tulobuterol (in neither the presence nor absence of metoprolol), in the same concentration range as isoprenaline and adrenalin, (0.001-50 mumol/L) was found to have no effect on the electrically evoked contraction of gravid human uterine muscle strips.

Controlled trial of hydration and bed rest versus bed rest alone in the evaluation of preterm uterine contractions

Patients who are seen with uterine contractions but without documented change in cervical dilation or effacement are often treated with intravenous hydration before the initiation of intravenous tocolytic therapy. This is done with the intention of stopping uterine activity in patients with false preterm labor. A prospective randomized study was conducted to evaluate the effect of hydration on preterm uterine contractions in patients without proved preterm labor. A total of 28 patients were treated with bed rest and an intravenous bolus and subsequent continuous infusion of 5% dextrose in lactated Ringer's solution. A control group of 20 patients were treated with bed rest alone. Uterine activity and arrest of uterine contractions were compared between the two groups. Contractions stopped in 54% of the patients treated with hydration, whereas contractions stopped in 40% of the patients in the control group. This difference was not statistically significant. As a crossover study, those in the control group with contractions that continued after the initial observation period were subsequently treated with intravenous fluids. Only one patient in this group stopped contracting. Of all patients whose contractions with either therapy, 18% eventually were delivered of preterm infants. This included 20% of the hydration group and 14% of the control group. The use of hydration as a pretherapy indicator to differentiate true preterm labor from false preterm labor could not be supported by this study. In addition, patients whose contractions stopped with either hydration or bed rest are at increased risk of subsequent preterm delivery.

Salbutamol in the 1980s. A reappraisal of its clinical efficacy

Salbutamol (albuterol) is a beta 2-selective adrenoceptor agonist which accounts for its pronounced bronchodilatory, cardiac, uterine and metabolic effects. During the intervening years since salbutamol was first reviewed in the Journal (1971), it has become extensively used in the treatment of reversible obstructive airways disease. Numerous studies in this disease (including severe acute, childhood and exercise-induced asthma) have confirmed the bronchodilatory efficacy of salbutamol, and it has been shown to be at least as effective as most of the currently available bronchodilators, if not more effective. The onset of maximum effect of salbutamol is dependent on the formulation used and the route by which it is administered. In most patients inhaled salbutamol is a first-line therapy, since it offers rapid bronchodilation, usually relieving bronchospasm within minutes. Although oral salbutamol has often proved to be less efficacious than the inhaled formulation, it still affords clinically significant bronchodilation, and it is particularly useful in those patients unable to coordinate the use of inhalers. Parenteral formulations of salbutamol are generally reserved for the treatment of severe attacks of bronchospasm and they are one of the treatments of choice in these life-threatening situations. Studies of the concomitant use of salbutamol and other agents such as anticholinergics, methylxanthines and beclomethasone dipropionate have usually shown a complementary response in the majority of patients, as might be expected from the different mechanisms of action of these groups of drugs. Salbutamol is generally well tolerated and any side effects observed are a predictable extension of its pharmacology. Since the frequency of side effects is dose related, and therefore dependent on the route of administration, it is not surprising that they are much more common following intravenous and oral rather than inhalation therapy. Tremor, tachycardia and hypokalaemia are the most frequently reported adverse effects. After nearly 20 years of use, salbutamol is well established as a 'first-choice' treatment in reversible obstructive airways disease. Indeed, throughout this time many new bronchodilatory agents have been studied but none have proved more effective. Clinical evaluation of salbutamol in the treatment of premature labour, hyperkalaemia and cardiac failure awaits further studies, although to date some encouraging results have been reported.

Asthma in pregnancy complicated by iatrogenic pulmonary oedema

We report a unique case of near fatal acute pulmonary oedema developing with intravenous ritodrine, given in an attempt to suppress premature labour. The novel aspect of the case is that the patient had also been treated in the previous week with high dose nebulized beta-agonists for an episode of acute severe asthma, demonstrating that this idiosyncratic reaction to beta-adrenergic agents only occurs with the intravenous route of administration. The management of acute severe asthma occurring in pregnancy is discussed with a review of previous literature regarding possible mechanisms of beta 2-agonist-induced pulmonary oedema.

Anaesthetic management and non-invasive monitoring for caesarean section in a patient with cardiomyopathy

This paper describes the anaesthetic management of a 29-year-old woman for an elective repeat Caesarean section. A diagnosis of peripartum cardiomyopathy (PPCM) had been made after her first delivery by Caesarean section three years earlier. Although the patient was currently asymptomatic, recent echocardiography demonstrated persistent left ventricular dilatation. The choice of haemodynamic monitors and the clinical significance of PPCM in this situation are discussed.

Maternal mortality from Mendelson's syndrome: an explanation?

There have been major changes in obstetric and anaesthetic practice since 1946, including the introduction of intravenous infusions, oxytocics, tocolytic drugs, and endotracheal intubation. Some of these may adversely affect pulmonary water balance, which is probably already altered by pregnancy. These changes may have contributed to the increased severity of Mendelson's syndrome in pregnancy and to some extent explain the failure of prophylaxis to reduce maternal deaths.