Management

Critical Care in Obstetrics

Even though the basic principles of intensive care have role in management of obstetrics' patients, but they do have special challenges due to involvement of two lives and changes in maternal physiology

"CAD is uncommon in reproductive-aged women, but myocardial infarction has occurred because of the excessive hemodynamic stress of pregnancy. Management of CAD in a pregnant patient is similar to that for a non-pregnant patient" - Dr Sharad Srivastava Senior Consultant and HOD Department of Anaesthesia Fortis La Femme New Delhi

In spite of great advances in the medical field and improved quality of healthcare available in our country, the maternal mortality in India is very high (437 deaths per 1, 00,000 live births). Anemia, haemorrhage sepsis and toxemia of pregnancy are the most common causes of nearly 80,000 deaths a year in India, which can be prevented with better obstetric care. Recently, specialised obstetric intensive care units have been established for such purpose. However, this concept is yet to gain stronghold in our country. Due to lack of awareness and regular antenatal check-ups, the critically ill patients are referred late, and often in a moribund condition with multiple-organ failure. Hence, the role of intensive care in providing support to failing organs becomes critical. In the ICU, the basic line of treatment involves treatment of shock, correction of anemia and control of infection. Even though the basic principles of intensive care have role in management of obstetrics' patients but they do have special challenges due to involvement of two lives and changes in maternal physiology. Some features of such a specialised care required during pregnancy are:

Intubation & Mechanical Ventilation

Due to fluid retention in pregnancy, there is swelling of mucosa of naso-oropharyngeal tract. This may lead to mucosal injury and bleeding during intubation and suction. Also, endotracheal intubation must be performed quickly because pregnant patients have lower oxygen reserves because of the decrease in Functional Residual Capacity (FRC) of lung. Ventilate pregnant patients to maintain their PaCO2 at approximately 30 mm Hg, the normal level during pregnancy. Avoid respiratory alkalosis because it may decrease uterine blood flow and, hence, foetal oxygenation.

Haemorrhagic Shock

In obstetrics, hemorrhagic shock is the commonest life-threatening condition. But, it is also the easiest to manage. Its common causes are placental abruption, placenta praevia, uterine rupture, postpartum haemorrhage primarily due to uterine atony and cervical or vaginal lacerations. The management requires immediate resuscitative measures, including administration of oxygen, intravenous volume replacement with fluids, plasma expanders, blood and its components. In ante-partum haemorrhage, once the patient is stable, immediately perform an abdominal ultrasound to categorically diagnose the cause of uterine bleeding. Foetal monitoring should be performed.

In post-partum haemorrhage, uterine atony can be treated with uterine massage, intramuscular administration of methylergonovine (0.2 mg), and intravenous oxytocin infusion. The next step is prostaglandin administration.

Prostaglandins increase myometrial intracellular free calcium concentrations and enhance the activity of other oxytocic agents.

If medical management fails, ligation and embolisation of the internal iliac or uterine artery has been used to control obstetric haemorrhage. Surgical exploration to repair lacerations and decrease blood loss by arterial ligation or hysterectomy may be required as a life-saving measure. Transcatheter arterial embolisation has been a recognised method of haemorrhage control and has been used successfully in the control of postpartum haemorrhage.

Pregnant patients in shock may require insertion of a pulmonary artery catheter. In normal pregnancy, the cardiac output increases as much as 30-50 per cent compared to pre-pregnancy levels, but the cardiac filling pressures are unchanged.

For sedation, meperidine and fentanyl are commonly used. Benzodiazepines may be used, but these may have depressive effects on foetal respiration. A patient who is critically ill and in shock requires vasoactive drugs. Ephedrine, which has both beta-2 properties and alpha-1 agonist properties, is known to increase uterine blood flow and maternal blood pressure. It is the vasoactive drug of choice to treat hypotension in pregnant patients.

Septic Shock

Septic shock may occur during pregnancy because of overwhelming infection caused by Gram-negative bacteria, viruses or fungi. Gram-negative bacteria such as Escherichia coli, Klebsiella species, Pseudomonas aeruginosa and Serratia species cause most cases of septic shock. The micro-organisms produce endotoxins that activate complement. The causes of septic shock are septic abortion, chorioamnionic and postpartum infections, pyelonephritis and respiratory tract infections.

Treatment requires immediate resuscitation, adequate tissue oxygenation, identification of the underlying cause of septic shock and treatment with anti-microbial therapy. Cultures of sputum, blood and urine are sent prior to antibiotic administration. A usual combination used often is penicillin, aminoglycoside and clindamycin or metronidazole. An alternate combination is a second or third-generation cephalosporin combined with metronidazole. Piperacillin-tazobactam is another combination that provides fairly comprehensive coverage for an intra-abdominal source of sepsis.

• Cardiogenic shock: The major cause of cardiogenic shock is severe valvular disease.
• Peripartum cardiomyopathy: It is an idiopathic disorder that occurs during the last month of pregnancy and up to six months post-partum. The treatment consists of diuretics, vasodilators for afterload reduction, digoxin and careful follow-up.
• Coronary Artery Disease (CAD): It is uncommon in reproductive-aged women, but myocardial infarction has occurred because of the excessive hemodynamic stress of pregnancy. Management of CAD in a pregnant patient is similar to that for a non-pregnant patient.

Pregnancy-Induced hypertension

Pregnancy-Induced hypertension (PIH) is also called toxemia or pre-eclampsia. It occurs most often in young women with first pregnancy. It is more common in twin pregnancies, in women with chronic hypertension, pre-existing diabetes, and in women who had PIH in a previous pregnancy. Eclampsia is a severe form of PIH. HELLP syndrome, (which is an abbreviation of Haemolytic anemia Elevated Liver enzymes and Low Platelet count) is a complication of severe pre-eclampsia or eclampsia. HELLP syndrome is a group of physical changes including the breakdown of red blood cells, changes in the liver and low platelets (cells found in the blood that are needed to help the blood to clot in order to control bleeding). With high blood pressure, there is an increase in the resistance of blood vessels. This may hinder blood flow in many different organ systems in the expectant mother including the uterus.

Treatment for PIH may include bed rest, anti-hypertensive medications such as a-methyl dopamine, calcium channel blocker and a-adrenergic blockers. Diuretics have limited role. Magnesium sulfate is the drug of choice in eclampsia. In PIH, foetal monitoring is important to check the health of the mother and child and termination of pregnancy by induction or Lower Segment Caeserian Section (LSCS) may be recommended in patients not responding to conservative treatment.

Amniotic Fluid Embolism

Amniotic Fluid Embolism (AFE) is a catastrophic peripartum syndrome that manifests as a sudden onset of severe dyspnea, hypoxemia, haemodynamic collapse, coagulopathy and seizures.

The amniotic fluid and foetal product may initiate an anaphylactoid reaction, resulting in endogenous mediator release and causing hypotension, tachycardia, hypoxemia and seizures, pulmonary arterial vasospasm and transient pulmonary hypertension, left ventricular failure, decreased cardiac output, and hydrostatic pulmonary edema. The diagnosis of AFE is based on a characteristic clinical picture. The three main goals of treatment are:

• Oxygenation.
• Maintaining cardiac output and blood pressure.
• Correcting coagulopathy.

Pulmonary Embolism

The risk for developing Deep Venous Thrombosis (DVT) and Pulmonary Embolism (PE) increases markedly during the advanced stages of pregnancy and is greatest during postpartum. The signs and symptoms of PE are more problematic because dyspnea and tachypnea are common in pregnancy. Treatment is with intravenous unfractionated heparin, unless a high risk or contraindication to the use of any anticoagulants exists. Monitor and keep the activated partial thromboplastin time in the therapeutic range, which is 1.5-2 times the baseline value. Low Molecular Weight Heparin (LMWH), which does not cross the placenta, can be administered once a day and does not require monitoring. Warfarin should be avoided throughout pregnancy because it can cause embryopathy characterised by mental retardation, optic atrophy, cleft lip, cleft palate, cataracts and haemorrhage.

Vena cava filters (Greenfield, stainless steel or titanium, bird's nest, Simon-Nitinol) are positioned within the infra-renal inferior vena cava to trap thrombi arising from the lower extremities.

Pulmonary: Pregnant women are predisposed to few pulmonary problems such as aspiration of stomach contents, pulmonary edema, pneumonia and ARDS. Pulmonary edema is usually seen in PIH or is induced by drugs such as methyl ergometrine, prostaglandin and beta adrenergic agents.

Cardiopulmonary Resuscitation

The precipitating events for cardiac arrest in pregnancy include Amniotic Fluid Embolism (AFE), PE, cardiomyopathy, anaesthetic complications, myocardial infarction and magnesium overdose. Place pregnant patients in a left lateral tilt position to avoid supine hypotension. Advanced Cardiac Life Support (ACLS) is provided according to ACLS standard protocols.

Need-of-the-hour

Availability of specialised obstetric intensive care can go a long way in decreasing maternal mortality. However, educating women to avail these facilities is crucial for success of this goal. Medical disorders should be treated in the antenatal period itself by the appropriate specialties. Early recognition of the patient going downhill before one or multiple systems start failing is as important as good intensive care once this does occur. Mortality increases directly with the number of organs failed and hence prevention is more important than treatment after failure.

sharad.srivastava@fortishealthcare.com