The use of labetalol for attenuation of the hypertensive response to endotracheal intubation in preeclampsia

The Risk for Neonatal Hypoglycemia and Bradycardia after Beta-Blocker Use during Pregnancy or Lactation: A Systematic Review and Meta-Analysis

Beta-blockers are often used during pregnancy to treat cardiovascular diseases. The described neonatal side effects of maternal beta-blocker use are hypoglycemia and bradycardia, but the evidence base for these is yet to be evaluated comprehensively. Hence, this systematic review and meta-analysis was performed to evaluate the potential increased risk for hypoglycemia and bradycardia in neonates exposed to beta-blockers in utero or during lactation. A systematic search of English-language human studies was conducted until 21 April 2021. Both observational studies and randomized controlled trials investigating hypoglycemia and/or bradycardia in neonates following beta-blocker exposure during pregnancy and lactation were included. All articles were screened by two authors independently and eligible studies were included. Pair-wise and proportion-based meta-analysis was conducted and the certainty of evidence (CoE) was performed by standard methodologies. Of the 1.043 screened articles, 55 were included in this systematic review. Our meta-analysis showed a probable risk of hypoglycemia (CoE—Moderate) and possible risk of bradycardia (CoE—Low) in neonates upon fetal beta-blocker exposure. Therefore, we suggest the monitoring of glucose levels in exposed neonates until 24 h after birth. Due to the limited clinical implication, monitoring of the heart rate could be considered for 24 h. We call for future studies to substantiate our findings.

Guidelines for the management of women with severe pre-eclampsia

OBJECTIVE

To provide national guidelines for the management of women with severe pre-eclampsia.

DESIGN

A consensus committee of 26 experts was formed. A formal conflict-of-interest (COI) policy was developed at the onset of the process and enforced throughout. The entire guidelines process was conducted independently of any industrial funding. The authors were advised to follow the principles of the Grading of Recommendations Assessment, Development and Evaluation (GRADE®) system to guide assessment of quality of evidence. The potential drawbacks of making strong recommendations in the presence of low-quality evidence were emphasised.

METHODS

The last SFAR and CNGOF guidelines on the management of women with severe pre-eclampsia were published in 2009. The literature is now sufficient for an update. The aim of this expert panel guidelines is to evaluate the impact of different aspects of the management of women with severe preeclampsia on maternal and neonatal morbidities separately. The experts studied questions within 7 domains. Each question was formulated according to the PICO (Patients Intervention Comparison Outcome) model and the evidence profiles were produced. An extensive literature review and recommendations were carried out and analysed according to the GRADE® methodology.

RESULTS

The SFAR/CNGOF experts panel provided 25 recommendations: 8 have a high level of evidence (GRADE 1+/-), 9 have a moderate level of evidence (GRADE 2+/-), and for 7 recommendations, the GRADE method could not be applied, resulting in expert opinions. No recommendation was provided for 3 questions. After one scoring round, strong agreement was reached between the experts for all the recommendations.

CONCLUSIONS

There was strong agreement among experts who made 25 recommendations to improve practices for the management of women with severe pre-eclampsia.

Pharmacological strategies to prevent haemodynamic changes after intubation in parturient women with hypertensive disorders of pregnancy: A network meta-analysis

Objective : This network meta-analysis (NMA) aimed to determine the relative efficacy and safety of pharmacological strategies used to mitigate haemodynamic instability by intubation for general anaesthesia in hypertensive parturient women undergoing caesarean section. Methods : We considered randomised controlled studies comparing the effects of pharmacological strategies used to alleviate haemodynamic instability during intubation in parturient women with hypertensive disorders of pregnancy. The primary endpoints were maximum blood pressure and heart rate after intubation, and secondary endpoints were the Apgar scores at 1 and 5 min. NMA allowed us to combine direct and indirect comparisons between strategies. Results : Twelve studies evaluating nine pharmacological strategies in 619 patients were included. According to the surface under the cumulative ranking curve, the maximal mean arterial pressure was lowest for high-dose remifentanil (99.4%) followed by nitroglycerin (73.6%) and labetalol (60.9%). The maximal heart rate was lowest for labetalol (99.9%) followed by high dose of remifentanil (81.2%) and fentanyl (61.6%). Apgar score at 1 min was higher with low-dose than with high-dose remifentanil (mean difference, 0.726; 95% confidence interval, 0.056 to 1.396; I2=0.0%). Conclusions : High-dose remifentanil produces minimum blood pressure changes, while labetalol is most effective in maintaining normal heart rate in parturient women with hypertensive disorders of pregnancy during caesarean section under general anaesthesia.

Effect on Neonatal Outcome of Pharmacological Interventions for Attenuation of the Maternal Haemodynamic Response to Tracheal Intubation: A Systematic Review

The primary aim of this systematic review was to assess the effect on neonatal outcome of pharmacological interventions used for attenuation of the haemodynamic response to tracheal intubation in patients undergoing caesarean Section under general anaesthesia. A systematic search of randomised controlled trials from 1990 to 2015 was conducted. The primary outcome measure was the Apgar score at five minutes and secondary outcomes were umbilical arterial blood gas parameters and neurological adaptive capacity scores. Twenty-seven randomised controlled trials (1,689 patients) were included in the qualitative synthesis. Only five studies using opioids (383 patients) and five studies using non-opioid analgesics (358 patients) were subjected to meta-analysis. The Apgar score at five minutes was significantly lower in neonates of opioid-treated mothers (mean difference: −0.29, 95% confidence interval −0.56 to −0.02, P-value=0.03) compared to mothers in the control group; the umbilical arterial pH was lower and there was a higher requirement for tactile stimulation in neonates. No difference was seen in Apgar scores of neonates of mothers administered non-opioid analgesics compared to placebo. No difference was observed in other parameters between opioid- or non-opioid-treated mothers. This review suggests that opioid interventions for attenuation of the haemodynamic response to tracheal intubation in pregnant patients under general anaesthesia affect neonatal Apgar scores at five minutes in neonates but the difference did not appear to be clinically meaningful. We were unable to demonstrate any difference in safety.

A Comparative Study of Intravenous Esmolol, Labetalol and Lignocaine in Low Doses for Attenuation of Sympathomimetic Responses to Laryngoscopy and Endotracheal Intubation

BACKGROUND

Direct layngoscopy and endotracheal intubation is a noxious stimuli and induces sympathomimetic responses. Although well tolerated in healthy subjects, it may impose life threatening arrhythmias, left ventricular failure or rupture of cerebral aneurysm in susceptible patients. Esmolol, Labetalol and Lignocaine attenuate these responses but are associated with side effects of bradycardia, hypotension etc. In lower doses, chances of these side effects are comparatively low. So we designed this prospective clinical trial to assess the efficacy of intravenous esmolol, labetalol and lignocaine in low doses for attenuation of sympathomimetic responses to endotracheal intubation.

MATERIALS AND METHODS

Seventy-five consenting patients of ASA physical status I or II of age range 20 to 60 years, scheduled for different general surgical procedures were randomly assigned to one of the three groups; group ES, group LB and group LG. Participants of group ES, group LB and group LG was given esmolol HCL 0.5 mg/Kg, labetalol HCL 0.25 mg/kg and lignocaine HCL 1 mg/Kg body weight respectively. Outcome variables were HR, SBP, DBP, MAP and RPP. These variables were recorded just after intubation and thereafter at 1,3,5, 7 and 10 minutes of intubation.

RESULTS

There was no statistically significant difference regarding the demographic characteristics of the groups. Heart rate and systolic blood pressure was lower throughout the study period in labetalol group. But the values of study parameters were always higher than the baseline in esmolol and lignocaine group. Values of mean arterial pressure was slightly higher in labetalol group but it was much higher in two other groups throughout the study period. Diastolic blood pressure was higher in all the groups. Values of rate pressure product was higher during intubation and at 1minute after intubation in labetalol group but thereafter it was always lower than baseline values.

CONCLUSION

Labetalol 0.25 mg Kg-1 is an effective and safe drug to be used for attenuation of sympathomimetic responses to endotracheal intubation. Esmolol 0.5 mg Kg-1 and lignocaine 1 mg Kg-1 are also effective to some extent and are safe.

Prevention of peri-induction hypertension in preeclamptic patients: a focused review

Many medications have been used to prevent the hypertensive response to the induction of general anesthesia and laryngoscopy in preeclamptic patients, with varying results. In this focused review, we summarize the available data and pharmacologic profiles of these drugs. Several different drug classes may be used safely; however, magnesium bolus, lidocaine, calcium channel antagonists other than nicardipine, and hydralazine are not recommended. Further research is warranted into the hemodynamic impact of varying the induction drug dose or combining different classes of drugs.

Diagnosis, evaluation, and management of the hypertensive disorders of pregnancy

OBJECTIVE

This guideline summarizes the quality of the evidence to date and provides a reasonable approach to the diagnosis, evaluation and treatment of the hypertensive disorders of pregnancy (HDP).

EVIDENCE

The literature reviewed included the previous Society of Obstetricians and Gynaecologists of Canada (SOGC) HDP guidelines from 2008 and their reference lists, and an update from 2006. Medline, Cochrane Database of Systematic Reviews (CDSR), Cochrane Central Registry of Controlled Trials (CCRCT) and Database of Abstracts and Reviews of Effects (DARE) were searched for literature published between January 2006 and March 2012. Articles were restricted to those published in French or English. Recommendations were evaluated using the criteria of the Canadian Task Force on Preventive Health Care and GRADE.

Attenuation of the pressor response to tracheal intubation in severe preeclampsia: relative efficacies of nitroglycerine infusion, sublingual nifedipine, and intravenous hydralazine

Background:

The pressor response to laryngoscopy is known to be exaggerated in patients with severe preeclampsia.

Objectives:

The aim of the present study was to compare the efficacies of continuous intravenous (IV) infusion of nitroglycerine, IV hydralazine, or sublingual nifedipine in modifying cardiovascular responses to endotracheal intubation, in women with severe preeclampsia undergoing cesarean delivery under general anesthesia.

Patients and Methods:

A total of 120 patients undergoing cesarean delivery were randomly divided into 3 groups, each receiving one of the following drugs before intubation: 5 µg/min nitroglycerine administered by continuous IV infusion (Group NTG, n = 40); a 10-mg capsule of nifedipine deposited sublingually (Group NIF, n = 40); or 5–10 mg hydralazine intravenously (Group H, n = 40). Heart rate (HR), systolic arterial pressure (SAP), diastolic arterial pressure (DAP), and mean arterial pressure (MAP) were simultaneously recorded in the mother at pre-induction, pre-intubation, and at 1, 3, 5, and 10 min after intubation.

Results:

In contrast to those in group NIF and group H, the patients in group NTG showed no significant increases in HR, SAP, DAP, or MAP after intubation, compared to baseline. The incidence of hypotension was significantly greater in group NIF than in group H or group NTG [15 (37. 5%) vs. 8 (20%) vs. 5 (12. 5%) respectively, P = 0. 025].

Conclusions:

In patients with severe preeclampsia undergoing cesarean delivery, a continuous IV infusion of nitroglycerine was able to attenuate the cardiovascular response to intubation to a greater extent than the use of sublingual nifedipine or IV hydralazine, without significant adverse effects on the newborn.

Comparison of esmolol and labetalol, in low doses, for attenuation of sympathomimetic response to laryngoscopy and intubation

Objective:

The present study compared the efficacy of esmolol and labetalol, in low doses, for attenuation of sympathomimetic response to laryngoscopy and intubation.

Design:

Prospective, randomized, placebo controlled, double-blinded study.

Setting:

Operation room.

Patients and Methods:

75 ASA physical status I and II adult patients, aged 18-45 years undergoing elective surgical procedures, requiring general anesthesia and orotracheal intubation.

Interventions:

Patients were allocated to any of the three groups (25 each)-Group C (control)10 ml 0.9% saline i.v. Group E (esmolol) 0.5 mg/kg diluted with 0.9% saline to 10 ml i.v. Group L (labetalol) 0.25 mg/kg diluted with 0.9% saline to 10 ml i.v. In the control group 10 ml of 0.9% saline was given both at 2 and 5 min prior to intubation. In the esmolol group 0.5 mg/kg of esmolol (diluted with 0.9% saline to 10 ml) was given 2 min prior and 10 ml of 0.9% saline 5 min prior to intubation. In the labetalol group 10 ml of 0.9% saline was administered 2 min prior and 0.25 mg/kg of labetalol (diluted with 0.9% saline to 10 ml) 5 min prior to intubation. All the patients were subjected to the same standard anesthetic technique.

Measurements:

Heart rate (HR), systolic blood pressure (SBP) and diastolic blood pressure (DBP) were recorded prior to induction, at time of intubation and 1, 3, 5, and 10 min after intubation. Mean arterial pressure (MAP) and rate pressure product (RPP) were calculated. Abnormal ECG changes were also recorded.

Results:

Compared to placebo and esmolol (0.5 mg/kg), labetalol (0.25 mg/kg) significantly attenuated the rise in heart rate, systolic blood pressure, and RPP during laryngoscopy and intubation. However, the difference was not statistically significant among the values for DBP and MAP.

Conclusion:

In lower doses, labetalol (0.25 mg/kg) is a better agent than esmolol (0.5 mg/kg) in attenuating the sympathomimetic response to laryngoscopy and intubation.

Therapeutics and anaesthesia

Many aspects of hypertension care outside pregnancy may be applied in pregnancy, but little information is available on which to base decision-making. It would seem reasonable to continue previous dietary salt restriction and physical activity in women with pre-existing (and controlled) hypertension, encourage a heart-healthy diet in all women with a hypertension disorder of pregnancy, and take patient preference into account when deciding on place of care. Although bed rest has become a key part of obstetric practice and for care of women with a hypertension disorder of pregnancy, in particular, the evidence is lacking to support this practice. This may also increase thromboembolic risk. Antihypertensive treatment is strongly advised for women with severe hypertension. The most common agents are parenteral labetalol, hydralazine, or oral nifedipine capsules. Clinicians should familiarise themselves with multiple agents. Until the role of antihypertensive treatment for non-severe hypertension in pregnancy is clarified by ongoing research, clinicians should explicitly state an individual patient's blood pressure goal, which could reasonably be anywhere between 130/80 and 155/105 mmHg. Labetalol and methyldopa are used most commonly. Breastfeeding should be encouraged. Many risk factors for hypertension (e.g. obesity), as well as hospitalisation and pre-eclampsia, all increase the thromboembolic risk for pregnant women, and care providers should consider thromboprophylaxis in the appropriate setting. Finally, anaesthetists play a critical role in the management of women with a hypertension disorder of pregnancy, and should be involved earlier rather than later in the course of their care.

Pharmacotherapeutic options for the treatment of preeclampsia

PURPOSE

Pharmacotherapeutic options for the treatment of preeclampsia are reviewed.

SUMMARY

Risk factors for the development of preeclampsia include microvascular diseases, such as diabetes mellitus; vascular and connective tissue disorders; hypertension; antiphospholipid antibody syndrome; and nephropathy. Several pathophysiological factors contribute to the development of the preeclamptic state, including vasospasm onset, coagulation system activation, increased inflammatory response, and ischemia. The specific agents used for the treatment of preeclampsia are dependent on a number of factors including symptom severity, maternal or fetal compromise, the progression to eclampsia, gestational period, and cervical status. The diagnosis of preeclampsia beyond the gestation period of 38 weeks requires delivery. The presence of maternal compromise or eclampsia at gestation greater than 20 weeks also necessitates delivery. In cases of chronic or mild hypertension, oral methyldopa may be administered on an outpatient basis. Intravenous hydralazine is a commonly administered arteriolar vasodilator that is effective for hypertensive emergencies associated with pregnancies. The most common adverse effect of hydralazine administration is unpredictable hypotension. Labetalol decreases heart rate and may be preferred because of a lack of reflex tachycardia, hypotension, or increased intracranial pressure. However, the drug of choice for the prevention and control of maternal seizures in patients with severe preeclampsia or eclampsia during the peripartum period is i.v. magnesium sulfate. Therapeutic serum magnesium levels cause cerebral vasodilation, thereby reversing the ischemia produced by cerebral vasospasm during an eclamptic episode. The results of one study indicated that women receiving magnesium sulfate therapy had a 58% lower risk of eclampsia than placebo.

CONCLUSION

Magnesium sulfate remains the drug of choice for the prevention and treatment of preeclampsia. Alternative antihypertensive agents may provide additional benefit in the management of hypertension for preeclamptic patients.

Maternal morbidity, mortality, and risk assessment

Maternal deaths in developed countries continue to decline and are rare. Maternal mortality statistics are essentially similar in the United States and United Kingdom. However, the situation is completely different in developing countries, where maternal mortality exceeds 0.5 million every year. This article not only assesses morbidity risks in some of the leading causes of maternal death but also highlights strategies to minimize the risks and to prevent maternal morbidity and mortality.

Pre-eclampsia: fluids, drugs, and anesthetic management

Severe pre-eclampsia is a complex disease, which taxes the expertise of even the most experienced obstetric anesthesiologist. The treatment should focus on stabilization of blood pressure, optimization of fluid status, and prevention of convulsions. Neuraxial blocks for labor and delivery offer many benefits to the mother and her infant. For cesarean section, there is unequivocal evidence of superiority of neuraxial anesthesia over general anesthesia. If general anesthesia is needed, careful preanesthetic preparation and meticulous airway management is essential. The successful and safe peripartum management of the pre-eclamptic patient and her infant is a team effort among the anesthesiologist, obstetrician, and neonatologist.

Haemodynamic responses to laryngoscopy and intubation in patients with pregnancy-induced hypertension: effect of intravenous esmolol with or without lidocaine

The pressor response is known to be exaggerated in patients with pregnancy-induced hypertension, which can result in increased morbidity and mortality in both mother and newborn. Various pharmacological agents have been used before induction in an attempt to attenuate the adrenergic response but with varying degree of success. Esmolol, an ultra short-acting cardioselective beta-blocker with rapid onset and short elimination half-life, is an attractive choice for attenuating the adrenergic response in pregnant patients. In a prospective, randomised double blind study we evaluated the efficacy of two bolus doses of esmolol with or without lidocaine, in patients with pregnancy-induced hypertension. Eighty such patients undergoing lower segmental caesarean section were randomly divided into four groups and received the following study drugs before intubation: group I, esmolol 1 mg.kg(-1); group II, esmolol 2 mg.kg(-1); group III, esmolol 1 mg.kg(-1) and lidocaine 1.5 mg.kg(-1); and group IV, esmolol 2 mg.kg(-1) and lidocaine 1.5 mg.kg(-1). In groups II, III and IV, the changes in maternal heart rate, systolic blood pressure and mean arterial pressure in response to laryngoscopy and intubation were attenuated to a comparable degree (P > 0.05). No adverse effects were noticed in mother or baby. We conclude that esmolol 1 mg.kg(-1) with lidocaine 1.5 mg.kg(-1) is effective in attenuating the adrenergic responses to laryngoscopy and intubation in patients with pregnancy-induced hypertension.

Anaesthesia and analgesia for the critically ill parturient

Anaesthetic and analgesic techniques in the critically ill are determined largely by the nature of the presenting illness. The commonest conditions likely to present as life-threatening emergencies are pre-eclampsia, obstetric haemorrhage, cardiac disease and severe sepsis. Issues dictating choice of anaesthetic technique are the patient's ability to maintain her airway, coagulation status, intravascular volume and haemodynamic dependence upon sympathetic drive, and requirements for ventilatory support and intensive care. Fetal well-being is an issue in the antepartum period, uteroplacental blood flow should be maintained and hypotension avoided. Maternal survival takes priority, however, and occasionally general anaesthetic techniques must be used which lead to neonatal respiratory depression and requirement for ventilatory support. Anaesthesia itself is associated with known hazards. The risks of each technique must be balanced against possible benefits in the context of the presenting illness.

The generalizability of trial data; a comparison of beta-blocker trial participants with a prospective cohort of women taking beta-blockers in pregnancy

OBJECTIVE

To evaluate the generalizability of randomized controlled trial (RCT) data to obstetric practice, using the example of beta-blocker therapy.

STUDY DESIGN

Descriptive comparison of characteristics of participants, interventions, and outcomes assessed between a meta-analysis of trials of beta-blocker therapy in pregnancy, and a prospective cohort of beta-blocker exposed callers to Motherisk, a Teratology Information Service.

RESULTS

72 women (cohort) and 34 trials with 2474 participants (meta-analysis) were compared. The generalizability of trials was limited by an inadequate description of maternal demographics and indications for beta-blockers, and a focus on the effectiveness of beta-blockers as antihypertensives rather than on reproductive risks.

CONCLUSIONS

Some of these limitations could be rectified. Others cannot, such as evaluation of teratogenicity (for ethical reasons) or all indications for a drug (for practical reasons). Reference to observational literature is, and will likely remain, necessary to address the 'harm' side of the therapeutic equation in pregnancy.

Pre-eclampsia

Pre-eclampsia is associated with significant morbidity and mortality for mother and baby, but it resolves completely post partum. Despite a steady reduction in maternal mortality from the disorder in more developed countries, it remains one of the most common reasons for a woman to die during pregnancy. The disorder starts with a placental trigger followed by a maternal systemic response. Because both this systemic response and the woman's reaction to it are inconsistent, the clinical presentation varies in time and substance, with many different organ systems affected. With the increasing understanding of the disease process, there have been advances in management, such as antihypertensive therapy, magnesium sulphate, and fluid restriction.

Severe pre-eclampsia and eclampsia

The mainstay of the management of severe pre-eclampsia is early referral, stabilization of the mother with antihypertensive therapy and anticonvulsants if required, full assessment of the mother and the baby, and delivery on the best day in the best way. It is to be remembered that delivery is the long-term cure, but most women get worse after delivery and most maternal deaths occur postpartum. It is important that doctors have the training to be aware of the dangers of this condition, guidelines to follow and senior support. Lowering blood pressure has been associated with a reduction in the mortality from cerebrovascular accident and early use of antihypertensive agents is beneficial to both mother and baby. The main cause of death is now pulmonary oedema, with renal failure a rare complication. It is important that, after delivery, vigilance is maintained and fluid replacement is given with care. It is better to 'run them dry' than to give fluid replacement that may encourage pulmonary oedema. Followup is required with counselling about what has happened and the prospects of recurrence.

Risks and benefits of beta-receptor blockers for pregnancy hypertension: overview of the randomized trials

OBJECTIVE

Examine the benefits/risks of beta-blockers for pregnancy hypertension.

STUDY DESIGN

Meta-analysis of relevant trials identified by comprehensive literature review (1966-97).

RESULTS

Included were 30 trials for pregnancy hypertension, and four others for perinatal outcomes only. For mild chronic hypertension treated throughout pregnancy (n=2 trials), oral beta-blockers (compared with no therapy) were associated with an inconsistent increase in small for gestational age (SGA) infants (OR 2.46 [1.02, 5.92]). For mild-moderate 'late-onset' pregnancy hypertension (i.e. either chronic treated only late in pregnancy, or pregnancy-induced) (n=8 trials), oral beta-blockers (compared with no therapy) were associated with a decrease in severe hypertension (OR 0.27 [0.16, 0.451), borderline decrease in development of proteinuria (OR 0.69 [0.48, 1.02]), decrease in RDS (OR 0.33 [0.13, 0.85]), but a borderline increase in SGA infants (OR 1.47 [0.96, 2.26]). Beta-blockers were equivalent to other agents (n=15 trials). For severe 'late-onset' pregnancy hypertension (n=5 trials), i.v. labetalol produced less maternal hypotension (OR 0.13 [0.03, 0.71]) and fewer cesareans (OR 0.23 [0.13, 0.63]) than i.v. hydralazine/diazoxide.

CONCLUSIONS

It is not clear that the benefits outweigh the risks when beta-blockers are used to treat mild to moderate chronic or pregnancy-induced hypertension, given the unknown overall effect on perinatal outcomes. For severe 'late-onset' pregnancy hypertension, i.v. labetalol is safer than i.v. hydralazine or diazoxide.

Hypertension in pregnancy: new recommendations for management

Hypertension in pregnancy is a frequent complication that has substantial adverse perinatal outcomes. Hypertension may be preexisting (chronic) essential or secondary hypertension; a second entity is pregnancy induced (gestational hypertension, preeclampsia). Recent advances have identified newer markers for pregnancy hypertension: several potential candidate genes may explain the apparent family inheritance of preeclampsia, and some thrombophilic markers have been associated with the condition. Management options for mild to moderate hypertension include a short hospital stay to exclude ongoing severe hypertension and to ascertain fetal well-being. Outpatient care with appropriate maternal and fetal surveillance, including umbilical artery doppler velocimetry, is recommended for better perinatal outcomes. Acute care for severe hypertension includes the use of magnesium sulfate to prevent eclampsia and antihypertensive medication. Expeditious delivery is recommended when the maternal or fetal states cannot be stabilized. Follow-up after delivery allows the uncovering of any other coexisting hypertensive or cardiovascular disorder.

Anaesthesia for caesarean section in a patient with recent subarachnoid haemorrhage and severe pre-eclampsia

Subarachnoid haemorrhage is a leading 'indirect' cause of maternal death in the UK. We describe the case of a 43-year-old woman who presented with headache, photophobia and neck stiffness of sudden onset at 32 weeks' gestation. Cerebral computed tomography demonstrated subarachnoid blood in the cisterns around the midbrain, and oral nimodipine was started to prevent vasospasm. Preparations were made for endovascular coil embolisation in the event of identification of a posterior circulation aneurysm. However, angiography under general anaesthesia failed to reveal any vascular abnormality. On emergence from anaesthesia, headache persisted, and over the next 24 h severe pre-eclampsia developed. Magnesium sulphate was started, and urgent Caesarean section performed under general anaesthesia without incident. The rationale for the neuroradiological, obstetric and anaesthetic management is discussed.

Anesthetic management of preeclampsia/eclampsia

Preeclampsia/eclampsia affects only a small proportion of all pregnancies, yet accounts for much of the obstetric morbidity and mortality seen in the USA and UK. A full understanding of preeclampsia/eclampsia, its variable presentation and complex pathophysiology allows the consulting anesthesiologist to optimize a plan for anesthetic management of the afflicted patient.

Changes in maternal middle cerebral artery blood flow velocity associated with general anesthesia in severe preeclampsia

In women with severe preeclampsia, significant increases in mean arterial pressures (MAP) are common after rapid induction of general anesthesia (GA) and tracheal intubation. The objectives of this prospective study were to assess the effects of the rapid induction-intubation technique on middle cerebral artery (MCA) flow velocity in severe preeclampsia and to examine the correlation between mean MCA flow velocity (Vm) and MAP. Eight women with severe preeclampsia (study group) and six normotensive women at term (control group) scheduled to undergo cesarean section under GA were studied. Before induction, patients in the study group received i.v. labetalol in divided doses to lower diastolic pressures to <100 mm Hg. Anesthesia was induced with pentothal 4-5 mg/kg, followed by succinylcholine 1.5 mg/kg to facilitate tracheal intubation. A transcranial Doppler was used to measure Vm. Both Vm and MAP were recorded before induction and every minute for 6 min after intubation. In the study group, after the administration of labetalol, MAP decreased from 129 +/- 9 to 113 +/- 9 mm Hg (P < 0.05), and Vm decreased from 59 +/- 11 to 54 +/- 10 cm/s (P < 0.05). After intubation, MAP increased from 113 +/- 9 to 134 +/- 5 mm Hg (P < 0.001), and Vm increased from 54 +/- 10 to 70 +/- 10 cm/s (P < 0.001). In the control group, while MAP increased significantly from 89 +/- 6 to 96 +/- 4 mm Hg (P < 0.05) after intubation, the concurrent increase in Vm from 49 +/- 5 to 54 +/- 7 cm/s was not significant. There was a significant positive pooled correlation between Vm and MAP (r = 0.5, P < 0.0006) in the study group but not in the control group (r = 0.24). After induction and intubation, both Vm and MAP values were significantly increased in the study group patients at all observation points compared with the control group patients. The findings indicate that Vm increases significantly after rapid-sequence induction of GA and tracheal intubation in women with severe preeclampsia, and there seems to be a direct relationship between MAP and Vm.

IMPLICATIONS

In women with severe preeclampsia, rapid-sequence induction of general anesthesia and tracheal intubation can cause severe hypertension. Our results indicate that the increase in blood pressure is associated with a significant increase in maternal cerebral blood flow velocity and that there is a significant correlation between these two variables.

Modern management of eclampsia

Eclampsia, the occurrence of a seizure in association with pre-eclampsia, remains an important cause of maternal mortality and morbidity. Despite being recognised since antiquity, consistent management practices are still lacking. Given that the aim of good care is to prevent seizures, it is disappointing that in the majority of cases the first eclamptic convulsion occurs after admission to hospital. This indicates that either the women who are likely to have a convulsion were not identified accurately, or the treatment given was ineffective. The answer to poor management of eclampsia lies in better education and training of all obstetricians, anaesthetists, midwives, and general practitioners in the diagnosis and treatment of severe pre-eclampsia and eclampsia. Protocols for the management of fluid balance, antihypertensive and anticonvulsant therapies should be available and reviewed regularly. The universal adoption of such guidelines in all obstetric units would substantially reduce elements of substandard care which have repeatedly been identified in the triennial reports of the confidential enquiries into maternal deaths in the UK.

Perioperative management of intra-partum seizure

A young nulliparous woman previously diagnosed with pregnancy-induced hypertension suffered a seizure during active first stage labour. Pre-seizure blood pressure was borderline high but she did not fulfill other criteria for preeclampsia. She underwent emergency caesarean section for presumed eclampsia. Postoperatively, she deteriorated neurologically. CT scan showed an intracranial haemorrhage requiring neurosurgical intervention. The similarities of presentation of a primary cerebrovascular event and eclampsia following an intra-partum seizure made the differential diagnosis difficult.

Care of the patient with severe pregnancy induced hypertension

Pregnancy induced hypertension remains the largest cause of maternal death in the UK. This is often related to inadequate or incorrect care. Recent randomised studies have enabled evidenced based clinical practice to be directed to the management of this condition. This allows a logical stepwise management structure to be developed in each hospital to make sure all women at risk get the best care available. This starts with comprehensive antenatal care with close collaboration between all professionals involved, early referral to an outpatient daycare unit if hypertension develops or is suspected, early use of antihypertensive therapy to control blood pressure once the diastolic is persistently above 100 mmHg, the use of magnesium sulphate to control convulsions, delivery on the best day in the best way and careful fluid management after delivery. Postnatal care should also contain risk assessment to allow directed counseling to the women concerning subsequent pregnancies.

Controlling the hemodynamic response to laryngoscopy and endotracheal intubation

The hemodynamic response to the stress of laryngoscopy and endotracheal intubation does not present a problem for most patients. However, patients with cardiovascular or cerebral disease may be at increased risk of morbidity and mortality from the tachycardia and hypertension resulting from this stress. These hemodynamic effects gained notice after the introduction and use of muscle relaxants, such as curare and succinylcholine, for endotracheal intubation at the time of anesthesia induction. A variety of anesthetic techniques and drugs are available to control the hemodynamic response to laryngoscopy and intubation. The method or drug of choice depends on many factors, including the urgency and length of surgery, choice of anesthetic technique, route of administration, medical condition of the patient, and individual preference. The possible solutions number as many as the medications and techniques available and depend on the individual patient and anesthesia care provider. This paper reviews these medications and techniques to guide the clinician in choosing the best methods.

Use of glucagon to treat neonatal low-output congestive heart failure after maternal labetalol therapy

Labetalol is used to treat hypertensive crisis in women with preeclampsia. Glucagon was used as a nonselective beta-adrenergic agonist to treat a preterm infant with symptomatic beta-blockade caused by maternal labetalol therapy.

Effects of labetalol on uterine blood flow and cardiovascular hemodynamics in the hypertensive gravid baboon

OBJECTIVE

The purpose of this study was to investigate the effects of labetalol on uterine blood flow and cardiovascular parameters in acutely instrumented, hypertensive gravid baboons.

STUDY DESIGN

During the latter half of pregnancy six gravid baboons were acutely instrumented, with ultrasonic flow probes placed on ipsilateral, external iliac, and uterine arteries and a flow-directed pulmonary artery catheter in the pulmonary artery. After a stable arterial pressure baseline was obtained, norepinephrine was infused to increase mean arterial pressure by at least 20%. A 20-minute hypertensive steady state was obtained. Labetalol at 0.5 and 1.0 mg/kg was randomly infused, followed by a 2.0 mg/kg dose, each over 1 minute. A 20-minute recovery period followed every labetalol infusion, allowing the hypertensive steady state to reestablish. External iliac and uterine blood flow measurements were continuously recorded during the baseline and experimental trials. Mean arterial blood pressure, heart rate, pulmonary artery and capillary wedge pressure, central venous pressure, and cardiac output were obtained at 5, 10, and 15 minutes during each steady state and after each labetalol infusion.

RESULTS

Labetalol at all dosages significantly reduced the mean arterial pressure and the systemic vascular resistance at 1.0 and 2.0 mg/kg. External iliac blood flow was not consistently significantly reduced; however, uterine blood flow was significantly reduced after the 1.0 and 2.0 mg/kg labetalol dosages (p < 0.05). Although uterine vascular resistance tended to increase after the 1.0 and 2.0 mg/kg doses, statistical significance was not achieved.

CONCLUSION

Low-dose labetalol (0.5 mg/kg) significantly reduces the pharmacologic hypertensive gravid baboon's mean arterial blood pressure without adversely affecting uterine blood flow.

Nifedipine attenuates the hypertensive response to tracheal intubation in pregnancy-induced hypertension

Thirty women with pregnancy-induced hypertension (PIH) scheduled for Caesarean section under general anaesthesia were studied to evaluate the efficacy of sublingual nifedipine in attenuating the pressor response to laryngoscopy and tracheal intubation. The patients were randomly given either the contents of a nifedipine capsule 10 mg or placebo sublingually 20 min before induction of anaesthesia. Blood pressure and heart rate were recorded at various time intervals. There was a decrease in mean arterial blood pressure (MAP) after pretreatment with nifedipine (P < 0.01). The increase in MAP during laryngoscopy and intubation was higher in the control group compared with nifedipine pretreatment group (P < 0.01). During laryngoscopy and intubation, MAP decreased by 3 mmHg in the nifedipine pretreatment group, while there was an increase of 14 mmHg in the control group. Heart rate increased in both the groups during the laryngoscopy and tracheal intubation (P < 0.01) but the increase was higher in the nifedipine group than in the control group (P < 0.05). Neonatal Apgar scores in both the groups were comparable. These results suggest that sublingual nifedipine is effective in attenuating the hypertensive response to laryngoscopy and intubation but not the tachycardiac response in parturients with PIH.

The hemodynamic effects of intubation during nitroglycerin infusion in severe preeclampsia

The effectiveness of intravenous nitroglycerin infusion in lowering maternal blood pressure and in blunting the hemodynamic responses to endotracheal intubation was evaluated in six primigravid women with severe preeclampsia. Monitoring consisted of continuous electrocardiogram monitoring, arterial cannulation, and flow-directed pulmonary arterial catheterization in each patient. All patients underwent oxytocin induction of labor and crystalloid and/or colloid expansion to produce a pulmonary capillary wedge pressure of 10 to 15 mm Hg and a colloid osmotic pressure of greater than 17 mm Hg. Intravenous nitroglycerin was administered before induction of general anesthesia. The hemodynamic effects associated with endotracheal intubation revealed a change in the heart rate from 104 +/- 10 to 133 +/- 17 beats/min, an increase in mean arterial pressure from 134 +/- 12 to 164 +/- 32 mm Hg, and an increase in systemic vascular resistance from 1262 +/- 342 to 1351 +/- 259 dynes-sec-cm-5 that was accompanied by a small change in the cardiac index from 4.5 +/- 1.2 to 4.5 +/- 0.9 L.min-1.m-2.

Labetalol. A reappraisal of its pharmacology, pharmacokinetics and therapeutic use in hypertension and ischaemic heart disease

Since labetalol was first reviewed in the Journal (1978), its scope of therapeutic use has expanded and become better defined. Labetalol is an adrenoceptor blocking drug with combined alpha- and beta-blocking properties. These result in a more favourable haemodynamic profile for labetalol compared with 'pure' beta-blockers or pure alpha-blockers, but also contribute to a wider range, but not an overall increased incidence, of adverse effects. The drug is effective and well-tolerated in patients with all grades of hypertension, but is of particular value in special subgroups such as Black patients, the elderly and patients with renal hypertension. While comparative studies are not extensive, available data show that the drug reduces blood pressure to a similar extent, and in a similar proportion of patients, as 'pure' beta-blockers such as propranolol, pure alpha-blockers such as prazosin, calcium antagonists (nifedipine, verapamil), and centrally acting drugs (clonidine and methyldopa). Labetalol is very effective in hypertensive pregnant women and in hypertensive crises, where it provides good control of blood pressure without serious adverse effects, and where few therapeutic options exist. Few controlled studies have investigated the use of labetalol in deliberate induction of hypotension or prevention of hypertension during anaesthesia, and also in patients with ischaemic heart disease. However, available evidence suggests a role for labetalol in these indications and further studies should aid in clarification of its efficacy in these areas. Thus, with its broad scope of therapeutic use in hypertension labetalol remains an important therapeutic option, and the drug may well find an additional place in the treatment of myocardial ischaemia if further evidence confirms encouraging preliminary findings.

Partial attenuation of hemodynamic responses to rapid sequence induction and intubation with labetalol

The effectiveness of labetalol (a combination nonselective beta and alpha-1-adrenergic receptor antagonist) in modifying hemodynamic responses associated with rapid sequence induction and tracheal intubation was evaluated. In a double-blind study, 24 ASA physical status I or II male patients scheduled for elective surgery were given either IV labetalol, 0.25 mg/kg (n = 8) or 0.75 mg/kg (n = 8), or a saline placebo (n = 8). Five minutes later, patients were given oxygen by mask and IV vecuronium, 0.01 mg/kg. Ten minutes after giving labetalol or placebo, cricoid pressure was applied and anesthesia was induced with IV sodium thiopental (4 mg/kg) and succinylcholine (1.5 mg/kg) 1 minute prior to intubation. The mean duration of laryngoscopy was 17 +/- 3 seconds. Prior to induction, the 0.25 mg/kg and 0.75 mg/kg doses of labetalol significantly (p less than 0.05) reduced mean arterial pressure by 4.4 +/- 1.9 and by 8.6 +/- 2.0 mmHg, respectively, but did not significantly alter heart rate or cardiac output. The 0.75 mg/kg dose of labetalol also significantly (p less than 0.05) decreased total peripheral resistance by 10.1 +/- 3.0%. Within 30 seconds after intubation, patients in all three groups exhibited increases in heart rate, mean arterial pressure, total peripheral resistance, and rate pressure product and a decrease in stroke volume. However, patients in the 0.25 and 0.75 mg/kg labetalol groups, compared to those in the placebo group, had significantly lower increases in peak heart rate (33 +/- 2 and 27 +/- 3 vs. 44 +/- 7 beats/minute), peak mean arterial pressure (38 +/- 6 and 38 +/- 7 vs. 58 +/- 7 mmHg), and peak rate pressure product (7,726 +/- 260 and 7,215 +/- 300 vs. 14,023 +/- 250 units). The results show that these doses of labetalol significantly blunt, but do not completely block, autonomic responses to rapid sequence induction and intubation.