Problems not confined to obstetrics

VI 85 Problems not confined to obstetrics ALLER GIC R E A CT I O NS Patients may be mildly allergic to many substances and this may become better or worse during pregnancy Severe reactions, however, are rare on the labour ward Most severe reactions are either anaphylactic or anaphylactoid Anaphylactic reactions involve release of histamine and other inflammatory mediators from mast cells via cross-linkage of IgE molecules on the cell surface by the antigen molecule; this process requires prior exposure to the antigen Anaphylactoid reactions involve direct release of mediators from mast cells via interaction of molecules (e.g drugs) with the cell surface in a different way; this does not require prior exposure The difference is largely academic since the clinical presentation is identical Less commonly, direct complement activation may be involved Most severe reactions on the labour ward are caused by drugs, especially antibiotics, intravenous anaesthetic drugs (particularly suxamethonium) and oxytocin Some well-recognised cross-reactions exist, e.g up to 10% of individuals with true penicillin allergy are also allergic to cephalosporins Allergy to amide local anaesthetic drugs is rare but has been reported, as has allergy to preservatives used in local anaesthetic and other drug preparations Non-steroidal antiinflammatory drugs and paracetamol often cause rashes but these are usually mild following brief oral/rectal courses, although severe reactions have been reported following intravenous administration Reactions may also follow administration of gelatine intravenous fluids and blood Latex allergy has become an increasing problem amongst both medical staff and patients, driven by an increase in the wearing of gloves because of concern about transmission of blood-borne infection and the ubiquitous use of latex in home and work environments Latex allergy is more common in subjects with multiple exposures to latex such as medical or nursing staff, cleaners, those with neurological disease requiring repeated bladder catheterisation, e.g spina bifida, and those with allergy to certain foodstuffs, including avocados, bananas, kiwi fruit and chestnuts Finally, other conditions not primarily allergic may also present in a similar way, e.g amniotic fluid embolism Analgesia, Anaesthesia and Pregnancy: A Practical Guide Second Edition, ed Steve Yentis, Anne May and Surbhi Malhotra Published by Cambridge University Press ß Cambridge University Press 2007 85 Allergic reactions 205 Patients may have a history of previous allergic reactions to drugs or other substances, although many patients who give only a vague history are not truly allergic Problems/special considerations Features range from mild skin rashes to severe urticaria, hypotension, bronchospasm, abdominal pain, diarrhoea, a ‘feeling of impending doom’ and cardiovascular collapse Initial hypotension is largely related to profound vasodilation, which is followed by leakage of intravascular fluid into the interstitium Cardiac depression (thought to be caused by circulating inflammatory mediators) may also contribute to hypotension The cardiovascular effects are exacerbated by aortocaval compression Features usually occur within a few seconds or minutes of exposure to the allergen In Caesarean section in latex allergic subjects, anaphylaxis typically occurs 10–15 minutes after induction of anaesthesia and once surgery has started, since the most provocative stimulus is exposure via mucous membranes Since clinical features may develop at a time of great physiological change, e.g during Caesarean section or during/after delivery, it may be difficult to assess the situation and determine what has happened Administration of many different drugs together or within a short time is common and this may hinder the diagnosis (and is suspected of increasing the risk of a reaction) Management options Immediate management of severe reactions consists of intravenous adrenaline 100 mg boluses and fluids, with management of the airway and administration of oxygen Aortocaval compression must be avoided at all times Any potential for adrenaline to cause uteroplacental vasoconstriction and uterine hypotony is outweighed by the restoration of cardiac output Intravenous chlorphenamine 10 mg and hydrocortisone 200 mg may be given to reduce the effects of subsequent inflammatory mediator release For less severe reactions (e.g urticaria only), chlorphenamine alone may suffice In an acute reaction, blood should be taken for tryptase levels at and 6–24 hours The enzyme is normally present in mast cells and in miniscule amounts in the plasma; an increase in plasma concentration therefore represents mast cell degranulation (but does not distinguish between anaphylactic and anaphylactoid reactions) Immunoglobulin and complement levels may be suggestive, but not diagnostic, of an allergic response If a severe reaction is suspected, the patient should be referred for testing at least 4–6 weeks later; normally this will involve skin tests (prick testing +intradermal testing) Further tests may be performed on plasma (e.g radioallergoabsorbent test (RAST) looking for concentrations of specific antibody, e.g to latex) or occasionally basophils or other cellular components, if skin testing is not diagnostic The patient should be advised to obtain a ‘Medi-alert’ bracelet and given written details of all the drugs tested 206 Section – Pregnancy and the results, in case she should require a subsequent anaesthetic A copy of the letter should also be sent to her general practitioner It is important that mothers with a previous history of severe allergic reactions are identified antenatally Wherever possible, the previous anaesthetic record should be obtained and a plan for her care documented Management of the known allergic case includes a general state of readiness and awareness as well as the obvious avoidance of any known allergens Latex allergic patients may be identified from the history in most cases by asking about food allergies and skin reactions after exposure, e.g rubber gloves, condoms, etc If patients have had a previous severe reaction where the allergen is unknown, pretreatment with H1- and H2-antagonists + steroids should be considered, although whether this should be routinely done if the allergen is known and can be avoided is controversial Routine screening of all women by using skin or blood testing is generally not indicated, since precautions should be taken on the basis of a strong history even if testing produces negative results Key points • In severe allergic reactions, immediate management is with oxygen, adrenaline and intravenous fluids • Hydrocortisone and chlorphenamine are second-line drugs • Blood should be taken for mast cell tryptase levels as early as possible • Subsequent testing should include skin testing • Latex allergy is an increasingly common problem FURTHER READING Dakin MJ, Yentis SM Latex allergy: a strategy for management Anaesthesia 1998; 53: 774–81 Fisher MM, Bowey CJ Intradermal compared with prick testing in the diagnosis of anaesthetic allergy Br J Anaesth 1997; 79: 59–63 Mertes PM, Laxenaire MC Allergic reactions occurring during anaesthesia Eur J Anaesthesiol 2002; 19: 240–62 86 C A R D I O V A S C UL A R D I S E A S E Cardiac disease is the second most common cause of maternal death in the UK after psychiatric causes The spectrum of pre-existing cardiac disease affecting pregnant women has changed in the UK as rheumatic heart disease has become less common (though it is still a major problem in other parts of the world) and congenital heart disease more common, partly related to the improved survival of girls with congenital heart disease who undergo surgery during infancy and childhood 86 Cardiovascular disease 207 The most common acquired heart disease in the UK is ischaemic heart disease Possible epidemiological factors include an increased prevalence of risk factors, e.g smoking amongst younger women, increased age and obesity Problems/special considerations Although different sorts of cardiac disease require different management, there are general principles that are applicable to this heterogeneous group Many of these have been highlighted in recent Reports on Confidential Enquiries into Maternal Deaths/Maternal and Child Health, which have found the following: • There is a general failure fully to understand the impact of the normal physiological changes of pregnancy on pre-existing cardiovascular pathology (see Chapter 11, Physiology of pregnancy; p 27) • Management of women with cardiac disease is often undertaken by inappropriately experienced medical staff Consultants should be involved in management from early pregnancy onwards and should be prepared to seek advice from (and if necessary to refer patients onwards to) specialist cardiological units • There may be failure to carry out essential investigations such as chest radiography, whereas the radiation risks to the fetus are minimal but the information gained from the investigation may be life saving • There may be failure to communicate with other specialties involved in a woman’s care and failure to organise clear written plans for management of labour and delivery • The severity of the mother’s condition may be underestimated, either because of the above or because symptoms are mild or absent, or because they are mistaken for those of pregnancy Management options The pregnant woman with cardiac disease, whether congenital or acquired, should be seen as early as possible in her pregnancy Ideally she should be seen for preconceptual counselling when her risks (Table 86.1) and those of her baby can be fully discussed A full history and examination should be performed during the first trimester of pregnancy, and baseline cardiological investigations should be arranged These may include electrocardiography, chest X-ray, echocardiography and possibly cardiac catheterisation Severity of cardiac disease is frequently assessed by using the New York Heart Association (NYHA) classification, which although originally described for heart failure is a useful overall measure of severity: • NYHA I: no limitation of physical activity and no objective evidence of cardiovascular disease • NHYA II: slight limitation of normal physical activity and objective evidence of minimal disease 208 Section – Pregnancy Table 86.1 Risk of death or severe morbidity resulting from certain cardiac lesions in pregnancy Low risk (mortality 0.1–1.0%) • Most repaired lesions • Uncomplicated left-to-right shunts • Mitral valve prolapse; bicuspid aortic valve; aortic regurgitation; mitral regurgitation; pulmonary stenosis; pulmonary regurgitation Intermediate risk (mortality 1–5%) • Metal valves • Single ventricles • Systemic right ventricle; switch procedure • Unrepaired cyanotic lesions • Mitral stenosis; aortic stensosis; severe pulmonary stenosis High risk (mortality 5–30%) • NYHA III or IV • Severe systemic ventricular dysfunction • Severe aortic stenosis • Marfan’s syndrome with aortic valve lesion or aortic dilatation • Pulmonary hypertension (N.B mortality 30–50%) • NYHA III: marked limitation of physical activity and objective evidence of moderately severe disease • NYHA IV: severe limitation of activity including symptoms at rest and objective evidence of severe disease Women with cardiovascular disease graded NYHA I and II usually tolerate the physiological changes of pregnancy well, though it should be remembered that certain conditions (e.g mitral and aortic stenosis, pulmonary hypertension and complex lesions) may be dangerous even in the absence of symptoms Consideration should be given to the appropriate place for both subsequent antenatal management and delivery Referral to a local teaching hospital with facilities for cardiac surgery may be indicated, and in some cases it may be in the woman’s best interests to be referred to a supraregional unit Routine antenatal care is not adequate for women with cardiac disease Antenatal appointments need to be more frequent; there must be clear communication with the general practitioner and the community midwife and also with the woman herself, who should receive instructions about symptoms that demand immediate medical attention Serial investigations and careful documentation of symptoms 86 Cardiovascular disease 209 should alert medical staff to any deterioration in cardiac health, and it may be useful to admit women with cardiac disease for 24–48 hours towards the end of the second trimester of pregnancy in order to repeat investigations and arrange multidisciplinary review Women require careful monitoring for development of pre-eclampsia, since it may be poorly tolerated in the presence of cardiac disease Elective admission to hospital in the third or even second trimester may be useful to ensure the mother can rest, with due attention to antithrombotic prophylaxis and regular assessments Continuous oxygen therapy may also be given if required As a general rule, operative delivery should only be carried out if indicated for obstetric reasons or deteriorating maternal condition, and not just because the mother has cardiac disease Regional analgesia and anaesthesia can be safely provided for the majority of women with cardiac disease, even in those with fixed cardiac output (although this is more controversial), although this may be precluded by anticoagulation in certain cases Analgesia and anaesthesia should only be carried out in units familiar with the management of such high-risk patients The risk of endocarditis should be remembered and antibiotics given as appropriate The puerperium is a time of high risk for many women with cardiac disease, and vigilance should be maintained The mother with cardiac disease should be nursed on the delivery suite or high-dependency unit until all medical staff involved in her care agree that she can be safely returned to the general postnatal ward Haemodynamic parameters have usually returned to normal within 3–5 days but may take longer in severe cases, and rarely may never return to pre-pregnancy values Key points • Women with cardiovascular disease should be identified and assessed early in pregnancy, and referred to specialist units when necessary • Good communication between specialties is mandatory • Clear management plans should be written • Vigilance should be maintained into the puerperium FURTHER READING Dob DP, Yentis SM UK Registry of High-risk Obstetric Anaesthesia: report on cardiorespiratory disease Int J Obstet Anesth 2001; 10: 267–72 European Society of Cardiology Task Force Expert consensus document on management of cardiovascular diseases during pregnancy Eur Heart J 2003; 24: 761–81 Siu SC, Sermer M, Colman JM, et al Prospective multicenter study of pregnancy outcomes in women with heart disease Circulation 2001; 104: 515–21 Thorne SA Pregnancy in heart disease Heart 2004; 90: 450–6 210 87 Section – Pregnancy AR R H Y T H M I AS During pregnancy there is an increased incidence of both benign arrhythmias and arrhythmias associated with cardiac disease If the abnormal rhythm causes haemodynamic instability, there is potential for fetal compromise and treatment should be instituted Problems/special considerations • Sinus tachycardia is normal during pregnancy Superimposed supraventricular ectopic beats occur commonly, particularly in association with caffeine and alcohol consumption, and may cause palpitations and anxiety Underlying organic disease is extremely unlikely in these women, and they should be reassured and given advice about avoiding likely precipitators of the arrhythmia • Paroxysmal supraventricular tachycardia is more common in pregnancy and rarely indicates underlying organic disease Palpitations, dizziness and syncope may occur, and although attacks may terminate spontaneously with rest, persistent tachycardia should be treated acutely with either suitable antiarrhythmic agents (adenosine or verapamil) or with DC cardioversion In persistent cases, His bundle studies and subsequent ablation of abnormal conduction pathways may be indicated, although it is usual to wait until after delivery for such management • Atrial fibrillation is usually associated with mitral valve disease and less commonly with cardiomyopathy The major risks from atrial fibrillation in pregnancy are thromboembolic disease and pulmonary oedema Prophylactic anticoagulants should be used, and it may be necessary to consider full anticoagulation in some situations, such as during and immediately following DC cardioversion Pregnancy does not alter medical management of atrial fibrillation It is particularly important to confirm that therapeutic plasma levels of antiarrhythmic agents are achieved throughout the pregnancy • Ventricular ectopic beats are relatively common during pregnancy and may be either asymptomatic or noticed by the patient as palpitations No treatment is necessary other than reassurance that there is no sinister underlying cause • Ventricular tachycardia or fibrillation may occur in association with severe organic cardiac disease, such as myocardial infarction In such situations, pregnancy is of secondary concern, since the arrhythmia is usually life threatening, and the primary goal of treatment is termination of the arrhythmia by whatever means is effective • Conduction disorders require referral for cardiological opinion, since some cardiologists recommend aggressive management (permanent pacing) of even first-degree heart block during pregnancy, although this is disputed 87 Arrhythmias 211 Management options In general, pregnant women with cardiac arrhythmias should be assessed and treated in the same way as those who are not pregnant During an acute episode, it is especially important to avoid aortocaval compression since this will exacerbate any circulatory embarrassment All commonly used antiarrhythmics cross the placenta (and indeed may be administered to the mother to treat a fetal arrhythmia) There are published case reports of the use of most antiarrhythmic drugs during pregnancy but few welldesigned controlled studies Previous anxieties that b-blocking drugs caused intrauterine growth retardation appear to have been largely discounted, but maternal b-blockade may cause fetal bradycardia and make interpretation of the fetal heart rate trace difficult Consensus opinion recommends using the smallest dose of the most well-established drug that will achieve a therapeutic effect If DC cardioversion is performed during pregnancy, it is important to safeguard the airway and to remember the risks of aortocaval compression In practice, this means using rapid sequence induction of general anaesthesia and tracheal intubation, together with uterine displacement off the great vessels for women in the second half of pregnancy Prophylactic anticoagulation should be considered during and after DC cardioversion because of the increased risk of thromboembolic disease during pregnancy Agents that are associated with increased heart rate (e.g oxytocin, ephedrine) should be avoided, or used very cautiously if needed, in women at risk of tachyarrhythmias Key points • No antiarrhythmic drug is considered completely safe for use in pregnancy, but any cardiac arrhythmia compromising haemodynamic stability requires urgent treatment • Use of older and well-established antiarrhythmics is generally recommended for firstline management, but newer drugs should not be withheld if other means are unsuccessful • Relief of aortocaval compression is essential FURTHER READING Ferrero S, Colombo BM, Ragni N Maternal arrhythmias during pregnancy Arch Gynecol Obstet 2004; 269: 244–53 Gowda RM, Khan IA, Mehta NJ, Vasavada BC, Sacchi TJ Cardiac arrhythmias in pregnancy: clinical and therapeutic considerations Int J Cardiol 2003; 88: 129–33 Lewis N, Dob DP, Yentis SM UK Registry of High-risk Obstetric Anaesthesia: arrhythmias, cardiomyopathy, aortic stenosis, transposition of the great arteries and Marfan’s syndrome Int J Obstet Anesth 2003; 12: 28–34 212 Section – Pregnancy 88 PU L MO N A RY OE DE MA The pregnant mother may be at increased risk of developing pulmonary oedema because her cardiac output and blood volume are increased considerably compared with pre-pregnancy values This increase is greater in the mother with multiple pregnancy Colloid osmotic pressure is also reduced in pregnancy Problems/special considerations • Acute pulmonary oedema in the pregnant woman may mimic an acute asthmatic attack Attempts to treat the latter will tend to exacerbate the former • There are multiple aetiologies of pulmonary oedema in pregnancy, but a careful history will usually provide a diagnosis of the underlying cause Pulmonary oedema may occur: (i) As a complication of coexisting cardiac disease (ii) Secondary to complications of pregnancy, e.g pre-eclampsia, major obstetric haemorrhage, intrauterine fetal death, amniotic fluid embolism, peripartum cardiomyopathy (iii) Secondary to aspiration of gastric contents (iv) Secondary to major sepsis (v) Following therapeutic or recreational drug administration, e.g b-adrenergic agonists, glucocorticoids, oxytocics, cocaine (vi) Following excessive administration of intravenous fluid • Hypoxaemia caused by oedema is exacerbated by the increased oxygen demand of pregnancy and the reduced functional residual capacity and oxygen reserve Management options Women who are known to be at increased risk of developing cardiac failure should receive antenatal and intrapartum care in an obstetric unit with high-dependency and intensive care facilities on site Pulse oximetry is particularly useful since a fall in saturation may be an early sign of pulmonary oedema Women receiving b-adrenergic agonists must have fluid balance and electrolytes monitored rigorously, and supplementary oxygen therapy should be considered Invasive monitoring of central venous pressure should be considered if regional analgesia or anaesthesia is used in a woman who has been receiving b-agonists Appropriate investigations should be performed, including chest radiography, since this carries negligible risk to the fetus In the absence of any obvious cause for cardiac failure, it is important to consider the use of illicit drugs Invasive cardiovascular monitoring will guide diagnosis and treatment, and the mother should be transferred to a high-dependency or intensive care unit at the earliest possible opportunity 89 Cardiomyopathy 213 Oxygen therapy is invariably beneficial Delivery of the fetus reduces oxygen demand and relieves the physical effect of the gravid uterus on the diaphragm and lungs Dexamethasone, given to improve neonatal respiratory function, may worsen fluid retention Key points • • • • 89 Pulmonary oedema is uncommon in pregnancy but may be fatal Chest radiography should not be withheld Delivery of the fetus may be indicated The mother should be managed in a high-dependency or intensive care unit CA R DI O M Y O PA T H Y Pregnant women may have a pre-existing cardiomyopathy or may develop cardiomyopathy of pregnancy (peripartum cardiomyopathy – PPCM) • The causes of pre-existing cardiomyopathy are diverse and include infection, systemic disease such as sarcoidosis, infiltrative disease such as amyloid, toxins such as alcohol and cocaine, ischaemic heart disease and congenital cardiomyopathies Of this group, the most commonly encountered in the antenatal clinic are the congenital hypertrophic obstructive cardiomyopathies (HOCMs) • The aetiology of PPCM is unknown but viral or autoimmune myocarditis, or an exaggerated response to the haemodynamic stresses of pregnancy, has been suggested The classic criteria for diagnosis of PPCM are: (i) Development of cardiac failure in the last month of pregnancy or within months of delivery (ii) Absence of other aetiology for cardiac failure (iii) Absence of cardiac disease prior to the last month of pregnancy It has been suggested that the definition should be extended to include cardiac failure developing within the third trimester of pregnancy for which no other cause can be found, and echocardiographical evidence of left ventricular dysfunction The incidence of PPCM is estimated to be in 3000 pregnancies Functionally, patients with HOCM have an obstructive cardiomyopathy, whilst those with PPCM have a dilated cardiomyopathy Problems/special considerations • Patients with obstructive cardiomyopathy have a hypertrophied left ventricle and interventricular septum Mitral regurgitation is often present Any factors that increase myocardial contractility (b-agonists, circulating catecholamines) ... fluid into the interstitium Cardiac depression (thought to be caused by circulating inflammatory mediators) may also contribute to hypotension The cardiovascular effects are exacerbated by aortocaval... 205 Patients may have a history of previous allergic reactions to drugs or other substances, although many patients who give only a vague history are not truly allergic Problems/ special considerations... of positive inotropes such as digoxin (and parenteral inotropes such as dopamine and dobutamine in the acute situation), oxygen and diuretics, vasodilators to reduce afterload (but not angiotensin-converting