MEDICAL AND SURGICAL COMPLICATIONS DURING PREGNANCY

C H A P T E R 15 MEDICAL AND SURGICAL COMPLICATIONS DURING PREGNANCY CARDIOVASCULAR DISEASES CARDIAC ARREST Cardiac arrest is cessation of heart action. Ventricular standstill (asystole) and ventricular fibrillation are the immediate causes, but the underlying etiologies are most frequently acute myocardial hy-poxia or alteration in conduction or both. In obstetrics and gyne-cology, cardiac arrest occurs during induction of anesthesia and dur-ing operative surgery or instrumented delivery. Cardiovascular disease increases the risk of cardiac arrest, and hypoxia and hyper-tension are contributory causes. Cardiac arrest may follow shock, hypoventilation, airway obstruction, excessive anesthesia, drug ad-ministration or drug sensitivity, vasovagal reflex activity, myocar-dial infarction, air and amniotic fluid embolism, and heart block. Cardiac arrest occurs in 1:800 to 1:1000 operations and is apt to occur during minor surgical procedures as well as during major surgery. It occurs in 1:10,000 obstetric deliveries, usually opera-tive, complicated cases. Fortunately, it is possible to save at least 75% of patients when cardiac arrest occurs in the well-managed and well-equipped operating or delivery room. CARDIOPULMONARY RESUSCITATION (CPR) CPR is used for treatment of asphyxia or cardiac arrest (Fig. 15-1). Phase I: First Aid (Emergency Oxygenation of the Brain) Basic life support must be instituted within 3–4 min for optimal ef-fectiveness and to minimize permanent brain damage. Do not wait 423 Copyright 2001 The McGraw-Hill Companies. Click Here for Terms of Use. 424 BENSON & PERNOLL’S HANDBOOK OF OBSTETRICS AND GYNECOLOGY FIGURE 15-1. Technique of mouth-to-mouth insufflation. CHAPTER 15 MEDICAL AND SURGICAL COMPLICATIONS DURING PREGNANCY for confirmation of suspected cardiac arrest. Call for help, but do not stop preparations for immediate resuscitation. Step 1: Place patient supine on a firm surface (not a bed). Step 2: Determine whether the patient is breathing. If the patient is not breathing, take immediate steps to open the airway. In unconscious patients, the lax tongue may fall back-ward, blocking the airway. Tilt the head backward and maintain it in this hyperextended position. Keep the mandible displaced forward by pulling strongly at the an-gle of the jaw. If victim is not breathing continue with the following. Step 3: Clear mouth and pharynx of mucus, blood, vomitus, or for-eign material. Step 4: Separate lips and teeth to open oral airway. Step 5: If steps 2–4 fail to open airway, forcibly blow air through mouth (keeping nose closed) or nose (keeping mouth closed) and inflate the lungs 3–5 times. Watch for chest movement. If chest movement does not occur immediately and if pharyngeal or tracheal tubes are available, use them without delay. Tracheostomy may be necessary. Step 6: Feel the carotid artery for pulsations. a. If carotid pulsations are present Give lung inflation by mouth-to-mouth breathing (keep-ing patient’s nostrils closed) or mouth-to-nose breathing (keeping patient’s mouth closed) 12–15 times per min— allowing about 2 sec for inspiration and 3 sec for expi-ration—until spontaneous respirations return. Continue as long as the pulses remain palpable and previously di-lated pupils remain constricted. If pulsations cease, fol-low directions in step 6b. b. If carotid pulsations are absent Alternate cardiac compression (closed chest cardiac massage, Fig. 15-2) and pulmonary ventilation as in step 6a. Place the heel of one hand on the sternum just above the level of the xiphoid. With the heel of the other hand on top of it, apply firm vertical pressure sufficient to force the sternum about 4–5 cm (2 inches) downward (less in children) about 80–100 times/min. After 5 ster-nal compressions, alternate with 1 quick, deep lung in-flation. Repeat and continue this alternating procedure until it is possible to obtain additional assistance and more definitive care. Resuscitation must be continuous. Open heart massage should be attempted only in a hos-pital. When possible, obtain an ECG, but do not inter-rupt resuscitation to do so. 426 BENSON & PERNOLL’S HANDBOOK OF OBSTETRICS AND GYNECOLOGY FIGURE 15-2. Technique of external cardiac massage. Heavy circle in heart drawing shows area of application of force. Circles on supine figure show points of application of electrodes for defibrillation. Phase II: Restoration of Spontaneous Circulation Until spontaneous respiration and circulation are restored, there must be no interruption of artificial ventilation and cardiac massage while steps 7–13 are being carried out. The physician must make plans for the assistance of trained hospital personnel, cardiac mon-itoring and assisted ventilation equipment, a defibrillator, emer-gency drugs, and adequate laboratory facilities. Three basic ques-tions must now be considered. What is the underlying cause, and is it correctable? What is the nature of the cardiac arrest? What further measures will be necessary? Step 7: Provide for intubation, administration of 100% oxygen, and mechanically assisted ventilation. A cutdown for CHAPTER 15 MEDICAL AND SURGICAL COMPLICATIONS DURING PREGNANCY long-term IV therapy and monitoring should be esta-blished as soon as possible. Attach ECG leads and take the first of serial specimens for arterial blood gases and pH. Promote venous return and combat shock by elevat-ing legs, and give IV fluids as available and indicated. The use of firmly applied tourniquets or military anti-shock trousers (MAST suit) on the extremities may be of value to occlude arteries to reduce the size of the vascu-lar bed. Step 8: If a spontaneous effective heartbeat is not restored after 1–2 min of cardiac compression, have an assistant give epi-nephrine, 0.5–1 mg (0.5–1 mL of 1:10,000 aqueous solu-tion) IV every 5 min as indicated. Epinephrine may stim-ulate cardiac contractions and induce ventricular fibrillation that can then be treated by DC countershock (see step 11). Step 9: If the victim is pulseless for more than 10 min, give sodium bicarbonate solution, 1 mEq/kg IV, to combat im-pending metabolic acidosis. Repeat no more than one-half the initial dose every 10 min during cardiopulmonary re-suscitation until spontaneous circulation is restored. Mon-itoring of arterial blood gases and pH is required during bicarbonate treatment to prevent alkalosis and severe hy-perosmolar states. Step 10: If asystole and electromechanical dissociation persist, continue artificial respiration and external cardiac com-pression, epinephrine, and sodium bicarbonate. Monitor blood pH, gases, and electrolytes. Step 11: If ECG demonstrates ventricular fibrillation, maintain car-diac massage until just before giving an external defib-rillating DC shock of 200–300 J for 0.25 sec, with one pad-dle electrode firmly applied to the skin over the apex of the heart and the other just to the right of the upper sternum. Monitor with ECG. If cardiac function is not restored, re-sume massage and repeat shock at intervals of 1–3 min. Step 12: Thoracotomy and open heart massage may be considered (but only in a hospital) if cardiac function fails to return after all of the above measures have been used. Step 13: If cardiac, pulmonary, and central nervous system func-tions are restored, the patient should be observed carefully for shock and complications of the precipitating cause. HEART DISEASE Congenital heart disease is the principal cardiovascular problem complicating pregnancy in the United States. Rheumatic heart ... - tailieumienphi.vn