LEARNING OUTCOMES

At the end of the chapter the reader will be able to:

• outline the relevant physiological changes that occur during pregnancy
  
• list acute illnesses and deaths associated with pregnancy
  
• discuss the monitoring of the critically ill pregnant woman

INTRODUCTION

Maternal deaths are extremely rare in the UK. The maternal mortality for 2003–5, calculated from all maternal deaths directly or indirectly due to pregnancy, was 14 per 100 000 maternities (Confidential Enquiry into Maternal and Child Health [CEMACH] – Lewis 2007). Studies have shown that the care of critically ill patients in the UK is suboptimal (McQuillan et al. 1998); deficiencies in care are related to the failure to recognise and treat abnormalities in the patient’s airway, breathing or circulation, common causes for cardiorespiratory arrest (Resuscitation Council UK 2006). These deficiencies are also present in the care of pregnant patients and a leading factor in maternal deaths (Grady et al. 2007). CEMACH recognises these deficiencies and makes recommendations for the early recognition and management of severely ill pregnant women and impending maternal collapse.

Assessing and monitoring the critically ill pregnant woman can be challenging. This is, in part, related to the physiological changes that occur during pregnancy and because priorities of care extend not only to the patient but also to the care of the unborn fetus.

The acutely ill pregnant woman must be approached using a systematic ABCDE assessment as outlined in previous chapters, but modifications will be required. These modifications can by made only when the practitioner has a sound understanding of the physiological changes associated with pregnancy.

As with all specialist areas of acute care, expert advice should be summoned at the earliest opportunity. This has been highlighted as a common failure in managing the pregnant patient (Lewis 2007). In many cases effective resuscitation of the mother, which is the leading priority, is often the best way to optimise fetal outcome (Resuscitation Council UK 2006). Early advice and assistance should be summoned from obstetricians, midwives and paediatric staff, in addition to emergency teams. Dynamic and effective communication through these teams is essential in improving outcome.

The aim of this chapter is to understand the monitoring of the critically ill, pregnant woman. Emergency delivery of the child, both perinatal and postnatal, has not been discussed because it is beyond the scope of this chapter and book.

RELEVANT PHYSIOLOGICAL CHANGES THAT OCCUR DURING PREGNANCY

Pregnancy is a period of enormous physiological change mediated by the endocrine and paracrine systems and the physical effects of the uteroplacental unit (Hayes and Arulkumaran 2006).

Airway Changes

Increased mucosal oedema may be present in the airways, possibly as a result of increased total body water. Nasal congestion may also occur.

Changes Associated with Breathing

Functional residual capacity (FRC) is reduced (Adam and Osborne 2005) as a direct result of the gravid uterus, causing displacement of the diaphragm and intra-abdominal organs. FRC reduction may be as much as 20%, reducing significantly further in the supine patient. A decrease in FRC compromises gas exchange and reduces oxygen reserve, meaning that a patient will become hypoxaemic more quickly if breathing becomes compromised.

The basal respiratory rate is usually increased as a compensatory mechanism for a reduction in FRC and as a result of the stimulant effects of increased circulating progesterone (Bayliss and Millhorn 1992). Minute ventilation may increase by up to 50% through a combination of increased respiratory rate and to a lesser extent tidal volume; this results in a respiratory alkalosis. Oxygen consumption will increase because of fetal requirements and the increased work of breathing.

Changes Associated with Circulation

Circulating volume begins to increase in early pregnancy and can increase by up to 50% approaching term (Silversides and Coleman 2007). This, combined with the metabolic demands of the fetal–placental unit, causes an increase in cardiac output which may also be up to 50% (Adam and Osborne 2005). Hormonal changes influence vascular tone and vascular resistance falls: the increase in cardiac output may not be sufficient to compensate for this decrease, so blood pressure, and in particular diastolic pressure, may be lower than normal. Venous pressure increases as uterine size increases which may cause gravitational oedema (Hayes and Arulkumaran 2006).

Placental Blood Flow and Caval Compression

The uteroplacental circulation is a pressure-dependent system with no independent autoregulation (Adam and Osborne 2005). Fetal blood supply can be severely impaired by poor maternal blood flow/pressure. From early pregnancy the gravid uterus can compress the inferior vena cava, with a resultant decrease in right heart preload, reducing cardiac output and placental blood flow. This appears to be particularly evident in the supine position. Aortic compression may also occur but appears to be to a lesser extent.

Haematological Changes

Red cell volume increases but this is diluted by the increase in plasma volume creating a dilutional reduction in haemoglobin. The white blood cell count increases, although the platelet count remains fairly constant. An increase in clotting factors creates a hypercoagulable state. The dilution picture also results in a reduced colloid osmotic pressure which contributes further to the development of oedema (Bothamley and Boyle 2009).

Changes Associated with Disability (Neurological Function)

Cerebral blood flow remains unchanged during pregnancy (Silversides and Coleman 2007). Hyperglycaemia and glycosuria may occur although this can be related to gestational diabetes which affects 3–10% of pregnancies (Miller et al. 2008)

Changes Associated with Exposure

There is an obvious increase in body mass index (BMI) in pregnancy. Total body weight may increase by up to 17% (Silversides and Coleman 2007). Breast size increases significantly in preparation for lactation. The accumulation of body water and increases in venous pressure contribute to gravitational oedema.

Gastro-oesophageal reflux is almost universal in pregnancy and gastric and intestinal motility is reduced (Hayes and Arulkumaran 2006).

ACUTE ILLNESSES AND DEATHS ASSOCIATED WITH PREGNANCY

A considerable number of pregnancies are complicated by acute illness processes some of which are related to the physiological changes outlined above. Acute illness can lead to maternal death. CEMACH (Lewis 2007) defines the causes of maternal death as direct, indirect, late or coincidental and this is illustrated in Table 16.1.

Table 16.1 Causes of maternal death in the UK

Reproduced from Lewis (2007), with the permission of the Centre for Maternal and Child Enquiries.

Causes of direct maternal death from 1985 to 2005 were related to (in order of prevalence) the following.

Thrombosis/Thromboembolism

Thromboembolic disease is a very common condition in pregnancy, increasing the risk almost sixfold over the non-pregnant patient (Adam and Osborne 2005). It occurs as a result of venous stasis and the haematological changes outlined above. A thrombus may form, commonly in the deep veins of the legs, and emboli from this clot may ‘break off’ and occlude blood flow to vital areas, in particular the pulmonary circulation, which can cause hypoxia and cardiac arrest. Treatment is preventive; appropriate prophylaxis should be weighed against the risk of complications, and started accordingly (Bourjeily et al. 2010). The National Institute for Health and Clinical Excellence (2010) recommends that pharmacological prophylaxis should be offered to hospitalised women who are pregnant if certain other risk factors are present:

• Expected to have significantly reduced mobility for 3 or more days
  
• Critical care admission
  
• Dehydration
  
• Excess blood loss or blood transfusion
  
• Obesity (pre-pregnancy or early pregnancy BMI >30)
  
• One or more significant medical comorbidities
  
• Pregnancy-related risk factors (such as hyperemesis gravidarum, multiple pregnancy or pre-eclampsia).

It is important to emphasise that pharmacological management of venous thromboembolus should go hand in hand with other preventive measure such as graduated compression stockings and improving mobility.

Pre-Eclampsia/Eclampsia

Pre-eclampsia can be defined as pregnancy-induced hypertension in association with proteinuria or oedema (Grady et al. 2007). It occurs in 2-8% of pregnancies (Magpie Trial Collaborative Group 2002) and 1 in 10 pregnant women develops partial signs or symptoms, The aetiology of pre-eclampsia is not entirely understood but is thought to be related to placental hypoperfusion and endothelial cell injury. It may present during the latter half of pregnancy, intrapartum or postpartum (Adam and Osborne 2005). Pre-eclampsia is classified as mild or severe and may lead to multiple organ dysfunction if not managed appropriately. Pre-eclampsia is a progressive disorder that can be arrested only by delivery of the fetus (Adam and Osborne 2005); immediate management is based on prompt control of hypertension, meticulous fluid management, seizure prevention and safe delivery of the child.

Eclampsia is defined as the occurrence of one or more convulsions superimposed on pre-eclampsia. The management of both conditions should involve senior multi-specialty, multidisciplinary staff working to a standardised pattern of management guidelines (Grady et al. 2007)

Haemorrhage

Massive blood loss, defined as blood loss of more than 1000–1500 ml, as a leading cause of maternal mortality is usually related to peri-/postpartum loss rather than loss associated with first trimester bleeding (Grady et al. 2007). First trimester bleeding may be related to ectopic pregnancy and this should be considered where vaginal blood loss is observed with associated abdominal pain in early pregnancy. The management of massive haemorrhage is aimed at fluid resuscitation with surgical correction of bleeding. Correction of coagulation will also be required in line with massive blood transfusion protocol.

Amniotic Fluid Embolism

Amniotic fluid embolism (AFE) occurs when amniotic fluid, normally contained in utero enters the maternal circulation. This exposure is not uncommon (De Jong and Fausett 2003), and the maternal predisposition to react to the exposure creates the clinical syndrome (Grady et al. 2007). The response to the exposure is unpredictable and may be related to the constituents or volume of the fluid entering the circulation. Signs and symptoms are related to the respiratory and cardiovascular systems. Clark et al. (1995) contend that AFE closely resembles an anaphylactic reaction in response to fetal debris rather than an embolic event, and propose the term ‘anaphylactoid syndrome of pregnancy’.

Ectopic Pregnancy

Ectopic pregnancy occurs if a fertilised ovum is implanted outside the uterine cavity (Watkins 2010) because a fallopian tube fails in its normal action of transporting the ovum into the uterus (Alexander et al. 2006). Tubal rupture can occur and the products of conception are expelled into the peritoneal cavity. Haemorrhage occurs from the tubal placental site (Alexander et al. 2006), resulting in hypovolaemic shock. Fluid resuscitation is required with urgent surgical intervention to arrest bleeding.

Miscarriage

Miscarriage is very common, occurring in 25% of pregnancies (Drife and Magowan 2004). Acute illness after a miscarriage may be related to intrauterine haemorrhage or sepsis from retained products of conception.

Liver Dysfunction

HELLP syndrome (haemolysis, elevated liver enzymes and low platelets) can occur antenatally and may be related to pre-eclampsia, although pre-eclampsia does not always have to be present for it to occur (Adam and Osborne 2005). It occurs in predominantly white, multiparous women aged >25 and is the most common cause of severe liver disease in pregnancy (Cetin 2006). HELLP syndrome includes the clinical signs outlined above and is considered to be a variant presentation of pre-eclampsia; endothelial cell injury, haemolysis and platelets consumption are thought to be the causative factors. Treatment is aimed at early delivery and supportive care

Acute fatty liver in pregnancy is an uncommon but potentially fatal complication of pregnancy that results in microvesicular fat deposition in the liver, causing severe liver dysfunction (McNulty 2004). The aetiology of the condition is not entirely clear. Supportive care and expeditious delivery are essential to optimal maternal–fetal outcomes and remain as the mainstay treatment (Ko and Yoshida 2006).

Acute Illness Presentation Association with Indirect Causes

The most common cause for maternal death from indirect causes is related to cardiac disease, either acquired or congenital (Lewis 2007). This includes myocardial infarction, ischaemic heart disease, aortic dissection and pulmonary hypertension. All the above conditions will, in most cases, present physiological indication of deterioration before a terminal event.

MONITORING THE CRITICALLY ILL PREGNANT PATIENT

Assessing and Monitoring the Acutely Unwell Pregnant Patient

The Resuscitation Council UK (2006) recommend that clinical staff should follow the ABCDE approach when assessing (and treating) critically ill patients. This will help to ensure that critical illness is promptly identified and appropriately managed (Jevon 2010). The fundamental principles of this framework are outlined in Chapter 1. However, the approach should be undertaken with consideration of the physiological changes associated with pregnancy and uteroplacental circulation. The process is outlined below.

Airway

The airway should be assessed using a look-and-listen approach. This includes inspection for signs of obstruction/abnormality. Nasal congestion may affect voice sounds but if a patient is talking the airway is patent. Be aware that the changes in respiratory physiology, in particular diaphragmatic splinting from the gravid uterus, will give rise to an increase in respiratory rate and breathlessness may well occur, particularly on exertion. Airway sounds, such as stridor, wheeze, gurgling or any stertorous breathing, are abnormal signs and require immediate treatment. In any case of partial airway obstruction high-flow oxygen should be delivered at the earliest opportunity; oxygen administration in the acutely unwell patient is discussed in depth in Chapter 1. As with any airway abnormality help should be summoned immediately from those with advanced airway skills. Simple manoeuvres such as head tilt/chin lift and/or jaw thrust are applicable to the pregnant patient; oropharyngeal airways may be of use if the tongue is the cause of obstruction; the use of nasopharyngeal airways may be limited by the presence of nasal congestion. As pregnancy progresses difficulties in endotracheal intubation and bag–valve–mask ventilation should be anticipated (Walls and Murphy 2008), reinforcing the requirement for senior support.

Breathing

Breathing respiratory assessment should occur as outlined in Chapter 3. The patient’s general appearance may be one of anxiety or exhaustion, or she may be unresponsive. Hypoxia and hypercapnia can alter mental state, and confusion/delirium may be present (Higgins and Guest 2008). Respiratory rate, pattern and chest excursion should be recorded. Changes in respiratory rate can be the most important early clinical manifestation of critical illness (Goldhill et al. 1999); however, respiratory rate can be altered in pregnancy and should be reviewed in comparison to previous recordings.

The decrease in FRC and increased metabolic demands reduce oxygen reserve, which may herald more rapid respiratory decompensation than observed in the non-pregnant patient. Thus airway and/or breathing problems must be recognised immediately and experienced assistance summoned at the earliest opportunity. High-concentration oxygen supplementation will be indicated, to optimise delivery to the maternal and fetal cells. Able patients with respiratory compromise tend to position themselves to maximise lung expansion, in many cases an orthopnoeic position. This may cause further diaphragmatic splinting in the pregnant patient. Likewise the supine position will further reduce FRC. Patients should be asked what position eases any distress and assisted accordingly. The effects of the right lateral position on caval blood flow and cardiac output must be considered.

Pulse oximetry can aid respiratory assessment; however, this does not provide information on haemoglobin concentration, oxygen delivery to the tissues or ventilatory function, so a patient may have normal oxygen saturations yet still be hypoxic (Higgins 2005). Pulse oximetry can, however, provide a useful ‘trend view’ of oxygenation, response to therapy and indication of deterioration and is thus indicated in any acutely unwell patient.

Arterial blood gas (ABG) analysis provides valuable information about a patient’s respiratory and metabolic function (Allen 2005) and is discussed in depth in Chapter 3. It may be performed as a one-off or serial investigation in monitoring the pregnant patient. Measured values will guide therapy, e.g. oxygen delivery or ventilatory support. Other useful parameters, such as blood acidity/alkalinity, haemoglobin concentration and electrolyte levels, may also guide other aspects of patient management. In the unstable patient arterial cannulation is of benefit for serial analysis and haemodynamic monitoring (Grady et al. 2007).

Circulation

Assessment of circulation should be performed as outlined in Chapter 1. When assessing circulation note that oedema may be present. The dilutional anaemia of pregnancy may influence the patient’s colour, giving a paler look than normal; however, this should be considered against other vital signs.

Capillary refill time (CRT) may be normal or increased due to a decrease in vascular resistance and increase in circulating volume. The fingers and the lower limbs may be oedematous, the soft tissues may become tense and the digital vessels may throb (Nihoyannopoulus 2007).

As a result of increases in circulating volume and cardiac output fluid loss may be difficult to detect until a significant amount of fluid has been lost. Insensible fluid losses may increase and certain specific complications of pregnancy such as hyperemesis gravidarum (severe vomiting during pregnancy) may influence hydration state. Thus, the practitioner must be aware that dehydration may be evident despite clinical presentation suggesting otherwise. Jugular venous pressure may be increased (Nihoyannopoulus 2007) but may be related to increases in intrathoracic pressure rather than circulatory overload.

Bleeding during pregnancy is common and loss may be obvious or concealed; per vagina losses should be assessed and the duration of any bleeding noted.

Pulse rates may be higher than those of non-pregnant patients yet persistent tachycardia is an abnormal sign and warrants further investigation. Pulse rate irregularity is again an abnormal sign and may indicate underlying cardiac dysfunction or electrolyte imbalance. In both cases, electrocardiogram rhythm analysis and diagnostic 12-lead ECG are required. Many pregnant patients experience palpitations, and premature atrial and ventricular contractions, and these are usually benign (Nihoyannopoulus 2007). However, any arrhythmias together with adverse signs, such as changes in blood pressure, changes in level of consciousness, chest pain or signs of heart failure, warrant urgent medical assessment.

Blood pressure should be recorded using appropriate cuff size; the increase in BMI associated with pregnancy may mean that a larger cuff should be used. Quinn (1994) suggests that automated blood pressure machines may underestimate pregnant women’s blood pressure by as much as 30 mmHg. Manual aneroid machines are recommended as a non-invasive technique in any acutely unwell patient. Blood pressure changes that occur during pregnancy are generally monitored throughout gestation, so ‘normal pregnant values’ should be available for the particular patient to allow comparison. Hypertension in pregnancy may be related to pre-eclampsia and, although certain definitions exist with regard to elevated blood pressure levels (Magpie Trial Collaborative Group 2003), any hypertension or episodes must be reported to senior specialist staff at the earliest opportunity.

Venous blood analysis should occur in any acute illness presentation; standard haematological and biochemical profiles should be requested. Liver function tests and clotting profiles are also indicated to identify any liver dysfunction.

Many cardiovascular problems are related to caval compression (Resuscitation Council UK 2006) and certain treatments may reduce this. The patient should be placed in the left lateral position and/or have gentle manual displacement of the gravid uterus to the left. This should be performed together with supportive measures such as high-flow oxygen delivery and fluid resuscitation (Resuscitation Council UK 2006)

Disability

The AVPU assessment tool (outlined in Chapter 6) provides a rapid assessment of the patient’s level of consciousness, and this should precede any more formalised tools such as the Glasgow Coma Scale. Blood glucose assessment should be undertaken at an early opportunity, not only to exclude hypoglycaemia but also to detect any gestational diabetes. Pupillary response to light and accommodation should also be assessed as outlined in Chapter 6. Alterations in levels of consciousness are an ominous sign; in particular if a score of P or U on the AVPU scale is evident, expert help should be summoned immediately. Confusion may be encephalopathic in origin and should alert the practitioner to liver dysfunction. The unconscious patient will normally need to be nursed in the lateral position to minimise the risk of soiling to the airway, particularly as gastro-oesophageal reflux is common; however, positioning the patient in the right lateral position may cause caval compression and should be avoided. The cause for any change in conscious level should be explored and history/charts noted to detect any reversible conditions. Convulsions, should they occur, may indicate eclampsia and immediate, expert assistance should be sought without delay.

Exposure

Exposure and overall assessment of the patient should occur as outlined in Chapter 1. Oedema may be noted throughout. Lower limbs must be assessed for any indication of thrombosis, redness, swelling or localised heat plus any pain/tenderness around the calf area should be noted. The patient should be assessed for signs of bleeding or fluid loss which will include concealed/obvious loss. ‘Dipstick’ urine analysis may indicate the presence of blood in the urine, indicating genitourinary trauma (Higgins 2008) or uterine blood loss. Glycosuria in pregnancy may indicate gestational diabetes, one of the most common medical conditions complicating pregnancy (Meltzer 2010), and blood glucose assessment should follow if glycosuria present. Proteinuria may indicate pre-eclampsia and should be reported immediately. The patient should be assessed for signs of liver dysfunction including jaundice, epigastric, right upper quadrant pain and evidence of ascites.

Cardiac Arrest During Pregnancy

Specific causes for cardiac arrest during pregnancy are outlined in Table 16.2; however, most are caused by the conditions outlined above, although many cardiovascular problems are caused by caval compression. In cardiac arrest standard principles of basic and advanced life support apply (Resuscitation Council UK 2006). However, obstetric and paediatric/neonatology staff should be summoned immediately as part of the emergency response team. During cardiac compressions a left lateral tilt >15° will relieve caval compression (Resuscitation Council UK 2006) improving right-sided venous return and optimising compressions. The patient will, however, require physical support in this position to maximise the efficacy of compressions, so wedges (e.g. Cardiff wedge) or firm pillows/spinal boards may be necessary. Left displacement of the uterus should also be performed and will be required together with lateral tilting. Cardiac compressions should be performed with a hand positioned one hand higher than normal to account for elevation of the diaphragm. Early endotracheal intubation is indicated to prevent aspiration.

Table 16.2 Specific causes for cardiac arrest during pregnancy

Adapted from Resuscitation Council UK (2006).

Caesarean section is indicated when initial resuscitation attempts fail because delivery of the fetus may improve maternal and fetal chances of survival (Resuscitation Council UK 2006), although this may be influenced by gestational age. This should occur within 5 minutes of the maternal cardiac arrest. This process requires considerable multidisciplinary and multi-specialty collaboration.

SCENARIOS

Scenario 1

Sarah, a 24-year-old woman, presents to A&E with abdominal and back pain and has experienced recent blood loss per vagina.

Your findings are as follows:

A – Airway is clear, Sarah is talking clearly and in sentences although very worried

B – Respiratory rate is 23, she looks rather pale and oxygen saturations are not picking up correctly

C – Sarah looks pale, CRT is 4 s, BP 100/70, pulse rate 115

D – Alert, but worried

E – Some lower abdominal tenderness. Sarah also states that she lost ‘quite a lot of blood’ from her vagina

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