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Antenatal anaesthetic assessment of the pregnant woman
OBSTETRIC ANAESTHESIA
Antenatal anaesthetic assessment of the pregnant woman
Learning objectives After reading this article you should be able to: identify patients who are most likely to benefit from antenatal anaesthetic assessment and a clear management plan initiate investigations for a pregnant woman with significant cardiac or respiratory disease describe the anaesthetic assessment of the obese patient for labour and delivery.
Rosamunde Burns Vicki Clark
Abstract
respiratory or neurological disease and are at high-risk of decompensating in pregnancy. Acquiring background information from past notes, X-rays and scans, or GP letters before seeing the patient, will guide management decisions. The co-morbidity dictates the physical examination in addition to the areas of importance to anaesthetists, that is the airway, venous access and the back. The airway assessment should be carried out as normal, but this may need repeated in labour as oedema may worsen Mallampatti scores. A change in voice or recent onset of hoarseness in the pre-eclamptic is a warning sign of laryngeal oedema. Some patients are referred because their venous access is difficult, especially if they have been intravenous drug abusers in
While complex cases are usually seen at the obstetric anaesthetic clinic, all anaesthetists should be competent in making an anaesthetic assessment of the antenatal patient. Pregnant women can present to any hospital as emergencies and they may need to be anaesthetized for either non-obstetric surgery or for labour and delivery by non-specialists. The routine anaesthetic assessment of the pregnant woman is described in addition to the assessment and management of the more common challenges these patients can present to the anaesthetist.
Keywords High-risk obstetric patients; multidisciplinary teamworking; obstetric anaesthetic clinics
Introduction In an ideal world all parturients should have an antenatal anaesthetic assessment, but the potential numbers and the unpredictability of the speciality make this impractical. Obstetric anaesthetists are usually asked to see the more complex patients and this role is expanding due to more co-morbidity in pregnant women, a rising caesarean section rate, and increasing obesity. The Association of Anaesthetists’ Guidelines for Obstetric Services set out that a system should be in place to allow the anaesthetist to have sufficient notice of high-risk cases (Table 1) and that tertiary referral centres should have a formal obstetric anaesthetic clinic. The referral should be done early so that appropriate investigations can be instigated and other specialists involved if necessary. However, many patients continue to be seen on an ad hoc basis or as emergencies and therefore all anaesthetists have to be competent in performing an anaesthetic assessment of the parturient.
Criteria for referral to anaesthetic clinic
Neurological History of brain surgery Myopathy Multiple sclerosis Stroke Spina bifida
Loco motor Scoliosis Achondroplasia Back surgery/injury
History and examination
Haematological Those on low-molecularweight heparin Haemoglobinopathy Coagulation disorders
Other Women who refuse blood Placenta accreta Uterine fibroids Previous epidural problems Previous anaesthetic problems Learning difficulties Needle phobia Body mass index (BMI) of 35e40: attach alert sticker and give epidural leaflet. No clinic appointment. BMI >40: please refer to anaesthetic clinic
Cardiac Respiratory Arrhythmias Severe asthma Congenital heart disease Cystic fibrosis Coronary heart disease Cardiac surgery
As well as the routine anaesthetic questions, those symptoms relevant to the referral have to be elicited. Of particular concern would be the woman who did not have normal exercise tolerance pre-pregnancy as these women may have significant cardiac,
Rosamunde Burns MBChB FRCA is a Consultant Obstetric Anaesthetist at the Simpson Centre for Reproductive Health, Edinburgh, UK. Conflicts of interest: none declared. Vicki Clark MBChB FRCA is a Consultant Obstetric Anaesthetist at the Simpson Centre for Reproductive Health, Edinburgh, UK. Conflicts of interest: none declared.
ANAESTHESIA AND INTENSIVE CARE MEDICINE 11:7
Table 1
255
Ó 2010 Elsevier Ltd. All rights reserved.
OBSTETRIC ANAESTHESIA
the past, or because they are needle-phobic. These patients are known to be at high risk and should be seen on admission to the labour ward when venous access should be secured exclusively by the anaesthetists. Where there are no peripheral veins visible, ultrasound identification is helpful and central venous access may be required. Examination of the back is usually performed in anticipation of regional anaesthesia and note made of ease or difficulty of palpation of the lumbar spinous processes, the presence or not of scoliosis, scars, hairy patches etc.
hypertensive response to laryngoscopy must be obtunded as this can cause myocardial ischaemia or cerebral bleed. Senior help should be sought. Obesity There is an ever-increasing number of pregnant women whose body mass index (BMI) is over 40 kg/m2. If indicated by the clinical history some of these patients may require an ECG in the antenatal period as some will be at risk of ischaemic heart disease. If the ECG is abnormal, referral to a cardiologist and an echocardiogram is indicated. The obese parturient is at increased risk of sleep apnoea.1 If symptoms suggestive of sleep apnoea are present, an urgent sleep study should be arranged as treatment with continuous positive airway pressure ventilation can reduce maternal hypoxia. Peripheral venous access may be impossible and central access indicated. If the upper arm is too big for conventional blood pressure cuffs, arterial line insertion should be discussed. The obese parturient has an increased risk of operative delivery which can be facilitated with an epidural top-up.3 Therefore early epidural insertion is advocated in this group as there is also an increased likelihood of difficult insertion and re-siting. General anaesthesia in this group can be challenging and should be avoided if at all possible, but is occasionally necessary if attempts at regional anaesthesia have failed. The intubation may be difficult and if predicted, requires an awake fibre-optic intubation. Both the obstetrician and the patient have to be made aware that in these circumstances, maternal safety is paramount and therefore it may not always be possible to provide category 1 caesarean section in the appropriate time frame. A stay in the high-dependency unit following delivery may be necessary for observations as postpartum haemorrhage and hypoxia are higher in this group.
Investigations Additional investigations depend on the co-morbidity. A cardiac patient will require an electrocardiogram (ECG) and usually an echocardiogram. A patient with severe asthma, cystic fibrosis or thoracic kyphoscoliosis will need pulmonary function tests and arterial blood gases if the oxygen saturation is abnormal. If clinically indicated, a chest X-ray may be helpful in severe cardiac or respiratory disease. An magnetic resonance imaging scan can identify spinal cord abnormalities, for example in spina bifida or neurofibromatosis, but many such investigations will have already been performed prior to the pregnancy and the patient should be asked to secure copies or her investigations from her GP/hospital.
Referral to other specialists The obstetric anaesthetist will often take on the role of the obstetric physician in centres where the latter do not exist with the aim of optimizing the patient’s condition in preparation for labour and delivery. However, the anaesthetist must refer on to other specialists if necessary, for example the cardiologists, respiratory physicians, neurologists, neurosurgeons etc. In very complex cases, multidisciplinary case conferences are undertaken.
Cardiac disease Cardiac disease is now the leading cause of maternal mortality overall. Congenital heart disease, ischaemic heart disease and hypertrophic cardiomyopathy are the commonest conditions seen. Occasionally rheumatic heart disease is seen in the immigrant population. Cardiac patients should be seen with the cardiologist and an echocardiogram performed, which can be repeated during the pregnancy if cardiac status is likely to deteriorate. Most of these patients should aim to achieve vaginal delivery and an epidural is recommended to reduce the sympathetic response to pain with invasive blood pressure monitoring. Should caesarean section be necessary, an incremental epidural technique or a combined spinal/epidural technique with a small spinal component can be used.4 If the patient has severe aortic stenosis or left ventricular failure, a general anaesthetic may be necessary. High-dependency care potentially in coronary care after delivery is indicated.
Examples of specific high-risk patients Patients at risk of haemorrhage Patients with placental abnormalities particularly placenta accreta1 are at increased risk of major haemorrhage and need to be seen in advance of their caesarean and told of the need for general anaesthesia, invasive monitoring and the possibility of transfusion and intensive care. Cell salvage and interventional radiology if available should be also mentioned. Women who refuse blood products also need to be seen before delivery2 and consent obtained for the alternative treatments that may be acceptable, for example erythropoietin, recombinant factor VIIa and cell salvage. A frank discussion on the possibility of death, and its impact on the family, as a result of these decisions if haemorrhage occurs is also necessary.
Haematological disease The majority of haematology patients referred to the anaesthetist will have coagulation issues due to low-molecular-weight heparin (LMWH) administration for pro-thrombotic risk like previous deep venous thrombosis and conditions such as, Factor V Leiden, protein C deficiency etc. Regional anaesthesia is not contra-indicated in these women but the timing of their LMWH is important, for example at least 12 hours must elapse between enoxaparin and a regional block if the patient is on a prophylactic dose and at least 24 hours if she is on a therapeutic dose. As part of the anaesthetic
Pre-eclampsia Patients with pre-eclampsia are oedematous and should have their airway, back and veins assessed as oedema can make access to all of these difficult. They can also have abnormal clotting and liver profiles (HELLP syndrome ¼ Haemolysis, Elevated Liver enzymes and Low Platelets), which may rule out regional anaesthesia. General anaesthesia in these women is challenging as they may be difficult to intubate and the
ANAESTHESIA AND INTENSIVE CARE MEDICINE 11:7
256
Ó 2010 Elsevier Ltd. All rights reserved.
OBSTETRIC ANAESTHESIA
assessment, she should be counselled on (i) the need to omit the next dose of the LMWH if she believes that labour has commenced, (ii) the use of a remifentanil patient-controlled analgesia technique in the event of recent LMWH administration and (iii) general anaesthesia if operative intervention is required. Similar rules apply for patients with thrombocytopenia although the threshold for withholding regional anaesthesia is controversial. Backs Many patients with chronic backache seek consultation with the anaesthetist for reassurance that regional anaesthesia will not worsen their backache. Patients who have had disc surgery in the relevant lumbar area can be told that epidural insertion may be difficult, there is an increased risk of accidental dural puncture and unilateral or patchy block. However spinal anaesthesia is usually straight forward. Regional anaesthesia is relatively contra-indicated in patients who have undergone metal instrumentation for scoliosis correction due to the small but devastating risk of infection. Those still keen on regional analgesia must be informed, in addition, of the risks common to those with disc surgery. Patients with spina bifida need to be referred early so that the anatomy of the defect can be defined to determine the risk of regional anaesthesia.5
Figure 1 Alert sticker for front of patient’s notes.
Follow-up Follow-up is important in complex cases so that the outcome can be improved for future potential pregnancies for that individual and also to build up departmental expertise of unusual conditions. A
Anaesthetic problems Patients with familial disorders, for example pseudocholinesterase deficiency and malignant hyperpyrexia, need early referral for adequate investigation. If these conditions cannot be ruled out, then general anaesthesia should be avoided and an early epidural is indicated. Mothers with complaints or issues about their analgesia/anaesthesia in her current or previous pregnancy should also be seen by a consultant anaesthetist.
REFERENCES 1 Prevention and management of postpartum haemorrhage. Royal College of Obstetricians and Gynaeclogists Greentop guideline no 52. Nov 2009. www.rcog.org.uk 2 The Seventh Report on Confidential Enquires into Maternal Deaths in the United Kingdom. In: Lewis G, ed. The Confidential Enquiry into Maternal and Child Health (CEMACH). Saving mothers’ lives: reviewing maternal deaths to make motherhood safer e 2003e2005. London: CEMACH, 2007. 3 Saravanakumar, Rao SG, Cooper GM. Obesity and obstetric anaesthesia. Anaesthesia 2006 Jan; 61: 36e48. 4 Ioscovich AM, Goldszmidt E, Fadeev AV, Grisanu-Granovsky S, Halpern SH. Peripartum anesthetic management of patients with aortic valve stenosis: a retrospective literature review. Int J Obstet Anesth 2009; 18: 379e86. 5 Kreeger RN, Hilvano A. Anesthetic options for the parturient with a neural tube defect. Anesthesiol Clin 2005; 43: 65e80.
Rarer disorders No article can comprehensively cover all conditions that may present to the anaesthetist and a good reference textbook is essential in every anaesthetic department (see recommended Further reading).
The management plan Once the anaesthetic management plan has been formulated, this needs to be communicated to the patient and the multidisciplinary team. There should be an ‘alert’ system in place for patients who have had antenatal anaesthetic assessment to make all staff aware when the patient is admitted. In our hospital we place a sticker on the front of the notes (Figure 1).
ANAESTHESIA AND INTENSIVE CARE MEDICINE 11:7
FURTHER READING Gambling David R, Joanne Douglas M, McKay Robert SF. Obstetric anesthesia and uncommon disorders. 2nd edn. Cambridge University Press, 2008.
257
Ó 2010 Elsevier Ltd. All rights reserved.
Antenatal anaesthetic assessment of the pregnant woman
Learning objectives After reading this article you should be able to: identify patients who are most likely to benefit from antenatal anaesthetic assessment and a clear management plan initiate investigations for a pregnant woman with significant cardiac or respiratory disease describe the anaesthetic assessment of the obese patient for labour and delivery.
Rosamunde Burns Vicki Clark
Abstract
respiratory or neurological disease and are at high-risk of decompensating in pregnancy. Acquiring background information from past notes, X-rays and scans, or GP letters before seeing the patient, will guide management decisions. The co-morbidity dictates the physical examination in addition to the areas of importance to anaesthetists, that is the airway, venous access and the back. The airway assessment should be carried out as normal, but this may need repeated in labour as oedema may worsen Mallampatti scores. A change in voice or recent onset of hoarseness in the pre-eclamptic is a warning sign of laryngeal oedema. Some patients are referred because their venous access is difficult, especially if they have been intravenous drug abusers in
While complex cases are usually seen at the obstetric anaesthetic clinic, all anaesthetists should be competent in making an anaesthetic assessment of the antenatal patient. Pregnant women can present to any hospital as emergencies and they may need to be anaesthetized for either non-obstetric surgery or for labour and delivery by non-specialists. The routine anaesthetic assessment of the pregnant woman is described in addition to the assessment and management of the more common challenges these patients can present to the anaesthetist.
Keywords High-risk obstetric patients; multidisciplinary teamworking; obstetric anaesthetic clinics
Introduction In an ideal world all parturients should have an antenatal anaesthetic assessment, but the potential numbers and the unpredictability of the speciality make this impractical. Obstetric anaesthetists are usually asked to see the more complex patients and this role is expanding due to more co-morbidity in pregnant women, a rising caesarean section rate, and increasing obesity. The Association of Anaesthetists’ Guidelines for Obstetric Services set out that a system should be in place to allow the anaesthetist to have sufficient notice of high-risk cases (Table 1) and that tertiary referral centres should have a formal obstetric anaesthetic clinic. The referral should be done early so that appropriate investigations can be instigated and other specialists involved if necessary. However, many patients continue to be seen on an ad hoc basis or as emergencies and therefore all anaesthetists have to be competent in performing an anaesthetic assessment of the parturient.
Criteria for referral to anaesthetic clinic
Neurological History of brain surgery Myopathy Multiple sclerosis Stroke Spina bifida
Loco motor Scoliosis Achondroplasia Back surgery/injury
History and examination
Haematological Those on low-molecularweight heparin Haemoglobinopathy Coagulation disorders
Other Women who refuse blood Placenta accreta Uterine fibroids Previous epidural problems Previous anaesthetic problems Learning difficulties Needle phobia Body mass index (BMI) of 35e40: attach alert sticker and give epidural leaflet. No clinic appointment. BMI >40: please refer to anaesthetic clinic
Cardiac Respiratory Arrhythmias Severe asthma Congenital heart disease Cystic fibrosis Coronary heart disease Cardiac surgery
As well as the routine anaesthetic questions, those symptoms relevant to the referral have to be elicited. Of particular concern would be the woman who did not have normal exercise tolerance pre-pregnancy as these women may have significant cardiac,
Rosamunde Burns MBChB FRCA is a Consultant Obstetric Anaesthetist at the Simpson Centre for Reproductive Health, Edinburgh, UK. Conflicts of interest: none declared. Vicki Clark MBChB FRCA is a Consultant Obstetric Anaesthetist at the Simpson Centre for Reproductive Health, Edinburgh, UK. Conflicts of interest: none declared.
ANAESTHESIA AND INTENSIVE CARE MEDICINE 11:7
Table 1
255
Ó 2010 Elsevier Ltd. All rights reserved.
OBSTETRIC ANAESTHESIA
the past, or because they are needle-phobic. These patients are known to be at high risk and should be seen on admission to the labour ward when venous access should be secured exclusively by the anaesthetists. Where there are no peripheral veins visible, ultrasound identification is helpful and central venous access may be required. Examination of the back is usually performed in anticipation of regional anaesthesia and note made of ease or difficulty of palpation of the lumbar spinous processes, the presence or not of scoliosis, scars, hairy patches etc.
hypertensive response to laryngoscopy must be obtunded as this can cause myocardial ischaemia or cerebral bleed. Senior help should be sought. Obesity There is an ever-increasing number of pregnant women whose body mass index (BMI) is over 40 kg/m2. If indicated by the clinical history some of these patients may require an ECG in the antenatal period as some will be at risk of ischaemic heart disease. If the ECG is abnormal, referral to a cardiologist and an echocardiogram is indicated. The obese parturient is at increased risk of sleep apnoea.1 If symptoms suggestive of sleep apnoea are present, an urgent sleep study should be arranged as treatment with continuous positive airway pressure ventilation can reduce maternal hypoxia. Peripheral venous access may be impossible and central access indicated. If the upper arm is too big for conventional blood pressure cuffs, arterial line insertion should be discussed. The obese parturient has an increased risk of operative delivery which can be facilitated with an epidural top-up.3 Therefore early epidural insertion is advocated in this group as there is also an increased likelihood of difficult insertion and re-siting. General anaesthesia in this group can be challenging and should be avoided if at all possible, but is occasionally necessary if attempts at regional anaesthesia have failed. The intubation may be difficult and if predicted, requires an awake fibre-optic intubation. Both the obstetrician and the patient have to be made aware that in these circumstances, maternal safety is paramount and therefore it may not always be possible to provide category 1 caesarean section in the appropriate time frame. A stay in the high-dependency unit following delivery may be necessary for observations as postpartum haemorrhage and hypoxia are higher in this group.
Investigations Additional investigations depend on the co-morbidity. A cardiac patient will require an electrocardiogram (ECG) and usually an echocardiogram. A patient with severe asthma, cystic fibrosis or thoracic kyphoscoliosis will need pulmonary function tests and arterial blood gases if the oxygen saturation is abnormal. If clinically indicated, a chest X-ray may be helpful in severe cardiac or respiratory disease. An magnetic resonance imaging scan can identify spinal cord abnormalities, for example in spina bifida or neurofibromatosis, but many such investigations will have already been performed prior to the pregnancy and the patient should be asked to secure copies or her investigations from her GP/hospital.
Referral to other specialists The obstetric anaesthetist will often take on the role of the obstetric physician in centres where the latter do not exist with the aim of optimizing the patient’s condition in preparation for labour and delivery. However, the anaesthetist must refer on to other specialists if necessary, for example the cardiologists, respiratory physicians, neurologists, neurosurgeons etc. In very complex cases, multidisciplinary case conferences are undertaken.
Cardiac disease Cardiac disease is now the leading cause of maternal mortality overall. Congenital heart disease, ischaemic heart disease and hypertrophic cardiomyopathy are the commonest conditions seen. Occasionally rheumatic heart disease is seen in the immigrant population. Cardiac patients should be seen with the cardiologist and an echocardiogram performed, which can be repeated during the pregnancy if cardiac status is likely to deteriorate. Most of these patients should aim to achieve vaginal delivery and an epidural is recommended to reduce the sympathetic response to pain with invasive blood pressure monitoring. Should caesarean section be necessary, an incremental epidural technique or a combined spinal/epidural technique with a small spinal component can be used.4 If the patient has severe aortic stenosis or left ventricular failure, a general anaesthetic may be necessary. High-dependency care potentially in coronary care after delivery is indicated.
Examples of specific high-risk patients Patients at risk of haemorrhage Patients with placental abnormalities particularly placenta accreta1 are at increased risk of major haemorrhage and need to be seen in advance of their caesarean and told of the need for general anaesthesia, invasive monitoring and the possibility of transfusion and intensive care. Cell salvage and interventional radiology if available should be also mentioned. Women who refuse blood products also need to be seen before delivery2 and consent obtained for the alternative treatments that may be acceptable, for example erythropoietin, recombinant factor VIIa and cell salvage. A frank discussion on the possibility of death, and its impact on the family, as a result of these decisions if haemorrhage occurs is also necessary.
Haematological disease The majority of haematology patients referred to the anaesthetist will have coagulation issues due to low-molecular-weight heparin (LMWH) administration for pro-thrombotic risk like previous deep venous thrombosis and conditions such as, Factor V Leiden, protein C deficiency etc. Regional anaesthesia is not contra-indicated in these women but the timing of their LMWH is important, for example at least 12 hours must elapse between enoxaparin and a regional block if the patient is on a prophylactic dose and at least 24 hours if she is on a therapeutic dose. As part of the anaesthetic
Pre-eclampsia Patients with pre-eclampsia are oedematous and should have their airway, back and veins assessed as oedema can make access to all of these difficult. They can also have abnormal clotting and liver profiles (HELLP syndrome ¼ Haemolysis, Elevated Liver enzymes and Low Platelets), which may rule out regional anaesthesia. General anaesthesia in these women is challenging as they may be difficult to intubate and the
ANAESTHESIA AND INTENSIVE CARE MEDICINE 11:7
256
Ó 2010 Elsevier Ltd. All rights reserved.
OBSTETRIC ANAESTHESIA
assessment, she should be counselled on (i) the need to omit the next dose of the LMWH if she believes that labour has commenced, (ii) the use of a remifentanil patient-controlled analgesia technique in the event of recent LMWH administration and (iii) general anaesthesia if operative intervention is required. Similar rules apply for patients with thrombocytopenia although the threshold for withholding regional anaesthesia is controversial. Backs Many patients with chronic backache seek consultation with the anaesthetist for reassurance that regional anaesthesia will not worsen their backache. Patients who have had disc surgery in the relevant lumbar area can be told that epidural insertion may be difficult, there is an increased risk of accidental dural puncture and unilateral or patchy block. However spinal anaesthesia is usually straight forward. Regional anaesthesia is relatively contra-indicated in patients who have undergone metal instrumentation for scoliosis correction due to the small but devastating risk of infection. Those still keen on regional analgesia must be informed, in addition, of the risks common to those with disc surgery. Patients with spina bifida need to be referred early so that the anatomy of the defect can be defined to determine the risk of regional anaesthesia.5
Figure 1 Alert sticker for front of patient’s notes.
Follow-up Follow-up is important in complex cases so that the outcome can be improved for future potential pregnancies for that individual and also to build up departmental expertise of unusual conditions. A
Anaesthetic problems Patients with familial disorders, for example pseudocholinesterase deficiency and malignant hyperpyrexia, need early referral for adequate investigation. If these conditions cannot be ruled out, then general anaesthesia should be avoided and an early epidural is indicated. Mothers with complaints or issues about their analgesia/anaesthesia in her current or previous pregnancy should also be seen by a consultant anaesthetist.
REFERENCES 1 Prevention and management of postpartum haemorrhage. Royal College of Obstetricians and Gynaeclogists Greentop guideline no 52. Nov 2009. www.rcog.org.uk 2 The Seventh Report on Confidential Enquires into Maternal Deaths in the United Kingdom. In: Lewis G, ed. The Confidential Enquiry into Maternal and Child Health (CEMACH). Saving mothers’ lives: reviewing maternal deaths to make motherhood safer e 2003e2005. London: CEMACH, 2007. 3 Saravanakumar, Rao SG, Cooper GM. Obesity and obstetric anaesthesia. Anaesthesia 2006 Jan; 61: 36e48. 4 Ioscovich AM, Goldszmidt E, Fadeev AV, Grisanu-Granovsky S, Halpern SH. Peripartum anesthetic management of patients with aortic valve stenosis: a retrospective literature review. Int J Obstet Anesth 2009; 18: 379e86. 5 Kreeger RN, Hilvano A. Anesthetic options for the parturient with a neural tube defect. Anesthesiol Clin 2005; 43: 65e80.
Rarer disorders No article can comprehensively cover all conditions that may present to the anaesthetist and a good reference textbook is essential in every anaesthetic department (see recommended Further reading).
The management plan Once the anaesthetic management plan has been formulated, this needs to be communicated to the patient and the multidisciplinary team. There should be an ‘alert’ system in place for patients who have had antenatal anaesthetic assessment to make all staff aware when the patient is admitted. In our hospital we place a sticker on the front of the notes (Figure 1).
ANAESTHESIA AND INTENSIVE CARE MEDICINE 11:7
FURTHER READING Gambling David R, Joanne Douglas M, McKay Robert SF. Obstetric anesthesia and uncommon disorders. 2nd edn. Cambridge University Press, 2008.
257
Ó 2010 Elsevier Ltd. All rights reserved.