الفهرس 
Hypertensive Emergencies in PregnancyOnly 14 pages are availabe for public view
 |  | from | 32 |  |  |
| | | from | 32 | | |
Abstract
H
ypertension is one of the most important chronic medical conditions affecting approximately one billion people worldwide (Lloyd-Jones et al., 2010). It is defined by the 7th Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7) as Blood Pressure above 140/90 mm Hg for most and above 130/80 mm Hg for diabetics and chronic kidney disease patients (Egan et al., 2010).
Hypertensive disorders in pregnancy (HDP) are associated with severe maternal obstetric complications and are a leading contributor to maternal mortality (Berg et al., 2010). Furthermore, HDP lead to preterm delivery, fetal intrauterine growth restriction, low birth weight and perinatal death. Hence, promoting quality services and enhancing communication among the providers who provide health care to pregnant women, including obstetricians, family practice physician, emergency department physicians, midwives, anesthesiologists, nurses and others became mandatory (Roberts et al., 2003).
Hypertensive emergency (crisis) is characterized by a severe elevation in blood pressure (> 180/120 mm Hg) complicated by evidence of impending or progressive target organ dysfunction, manifested by clinical sequelae or diagnostic test abnormalities. It requires immediate intervention with parenteral therapy and admission to a monitored setting (Chobanian et al., 2003).
A pregnant patient could experience a hypertensive emergency as sequelae of:
Pregnancy itself (eclampsia/severe pre-eclampsia), essential hypertension, renal disease such as: pyelonephritis, glomerulonephritis, systemic lupus erythematosus, renal artery stenosis, drugs either due to abrupt withdrawal of a centrally acting α2-adrenergic agonist (clonidine, methyldopa) or Phencyclidine, cocaine or other sympathomimetic drug intoxication, or interaction with monoamine oxidase inhibitors, endocrinal disease such as: pheochromocytoma, primary aldosteronism, glucocorticoid excess, renin-secreting tumors, thyrotoxic crisis, and finally, central nervous system disorders such as: cerebrovascular accidents (infarction/hemorrhage) and head injury (Polgreen et al., 2015).
The American College of Obstetrician and Gynecologists have classified the hypertensive disorders of pregnancy into the following four categories:
1. Pre-eclampsia is defined as the triad of hypertension, proteinuria and generalized edema, developing after the 20th week of gestation.
2. Chronic hypertension is the presence of sustained hypertension prior to pregnancy and continuing throughout the pregnancy.
3. Superimposed pre-eclampsia implies the development of increased blood pressure, proteinuria, and/or edema in a gravida with chronic hypertension.
4. Transient gestational hypertension refers to development of hypertension without proteinuria or edema in a previously normotensive gravida followed by return to normotension within 10 days postpartum.
Before any procedure is undertaken, it is mandatory to optimize the condition of the patient and to decide whether this patient needs ICU admission or not. BP should be controlled, primary medical cause of this crisis should be treated and proper monitoring should be initiated. Choice of analgesia will depend on obstetrical situation, the status of the patient and the condition of the fetus (if still in utero).
In preeclampsia and eclampsia, the use of continuous lumbar epidural analgesia is widely accepted and recommended, unless contraindicated. While planning for general anesthesia, the major hazards are difficulties in airway maintenance, excessive and aggregated response to laryngoscope and endotracheal intubation, interaction of anesthetic drugs with drugs used by obstetrician particularly magnesium sulphate (Parthasarathy et al., 2013).
The cardiovascular changes due to extubation could be as severe as pressor responses to intubation. At this moment, neither narcotics due to their respiratory depressant effects nor Magnesium Sulphate due to its neuromuscular blocking properties are likely to be ideal. The idea of extubating these patients in the deeper planes should be addressed very carefully due to high potential for airway management difficulties and aspiration (Zubair, 1996).
The delivery of the fetus and placenta is the treatment in many conditions, but the full recovery may take 10 days to 2 weeks. The airway management may be more difficult in the postoperative period due to the worsened laryngeal edema situation. Respiratory embarrassment may be severe and airway maintenance may be impossible without an endotracheal tube. The antihypertensive drugs should be continued in the postoperative period as long as indicated. It is very important to keep these patients pain free with good analgesia. Epidural analgesia is an ideal choice, if epidural catheter is in place. These patients should be closely and maximally monitored (both invasively and non-invasively) in the Intensive Care Unit at least for the first 24 hours (Magee et al., 2005).
Pregnancy may influence the course of renal disease. Some women with intrinsic renal disease, particularly those with baseline azotemia and hypertension, suffer more rapid deterioration in renal function after gestation. The presence of hypertension greatly increases the likelihood of renal deterioration. Regional anesthesia is considered safe if coagulation parameters are normal (Bajwa et al., 2012). If GA is to be performed, rapid sequence induction and measures to decrease pressor response to intubation should be done. Among GA, total intravenous anesthesia is considered better (Bajwa et al., 2010).
In thyrotoxicosis, adequate preoperative preparation minimizes the risk for perioperative thyroid storm; when time permits, the goal is to make the patient euthyroid. In an emergency, the hyperthyroid patient can be prepared for surgery with oral propylthiouracil, an intravenous glucocorticoid, sodium iodide, and propranolol. The anesthesia provider should be prepared to treat perioperative thyroid storm. No prospective randomized studies have evaluated the efficacy or safety of various anesthetic techniques in patients with hyperthyroidism (Chestnut et al., 2014).
Early diagnosis of pheochromocytoma during pregnancy and adequate adrenergic receptor blockade are essential to optimize maternal and fetal safety. Phenoxybenzamine is used for preoperative preparation of the pregnant patient. If beta-adrenergic receptor blockade is necessary, metoprolol can be used unless specifically contraindicated. Cesarean delivery, with or without concurrent tumor resection, has been accomplished safely with general anesthesia, epidural anesthesia and combined epidural-general anesthesia. During surgery, short-acting, titratable cardiovascular medications are preferred. Monitoring and therapy should be directed toward optimization of preload, afterload, and cardiac contractility for a patient with rapid changes in circulating concentrations of catecholamines. Attention to detail is likely more important than the choice of specific medications (Chestnut et al., 2014).
Patients with classic aldosteronism present with hypertension, hypokalemia, and elevated urine potassium levels. The pharmacologic agents that are helpful in patients who are not pregnant, such as spironolactone and angiotensin-converting enzyme (ACE) inhibitors, are contraindicated in patients who are pregnant. Methyldopa, beta blockers, and calcium channel blockers have been used with variable outcomes (Shigematsu et al., 2009). Regional anesthesia or GA may be used safely as long as attention is paid to hemodynamic stability, volume status, glucose levels and electrolytes (Shaikh et al., 2012).
When Cushing syndrome occurs during pregnancy, it may be difficult to detect clinically. Regional anesthesia or GA can be conducted. For GA, consider awake fiberoptic intubation because there is a suspected difficult airway. Muscle weakness may reduce the required dose for neuromuscular blockade, and the use of peripheral nerve stimulator is essential. If regional anesthesia is planned, technical difficulties may be encountered (Gambling et al., 2011).
In cerebrovascular accidents, brain MRI is considered the gold standard for the diagnosis. A combined spinal-epidural technique with a small volume of CSF withdrawal may provide labor analgesia. Intracranial subdural hematoma formation after epidural anesthesia and subarachnoid hemorrhage (SAH) after spinal anesthesia have been reported several times (El-Refai, 2013).
A head CT scan is always indicated in all head-injured patients with a depressed level of consciousness (Desjardins, 2008). Intubation and assisted ventilation, sedation, bolus mannitol therapy, and administration of prophylactic phenytoin should be done to reduce ICP, even prior to CT scan (Tawfik et al., 2015). Modest short-term hyperventilation is used to reduce the dangerously raised ICP. In some cases, termination of pregnancy is indicated in order to save the mother. Providing anesthesia for such a patient is challenging. Pregnancy aggravates the preexisting difficulty in airway management of head trauma patients. Cervical spine injury must be ruled out. Hypoxia, hypercarbia, and stress response during tracheal intubation should be avoided to minimize the rise in ICP. Aspiration prophylaxis is recommended, and induction of anesthesia must be rapid -albeit smooth- with the potential benefit of adjuvant drugs; short-acting opioids, lidocaine, and esmolol (Tawfik et al., 2015).