MEDICAL AND SURGICAL COMPLICATIONS DURING PREGNANCY ppt

423

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

15

MEDICAL AND

SURGICAL COMPLICATIONS

DURING PREGNANCY

CHAPTER

Copyright 2001 The McGraw-Hill Companies. Click Here for Terms of Use.

BENSON & PERNOLL’S

424 HANDBOOK OF OBSTETRICS AND GYNECOLOGY

FIGURE 15-1. Technique of mouth-to-mouth insufflation.

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.

CHAPTER 15

MEDICAL AND SURGICAL COMPLICATIONS DURING PREGNANCY 425

BENSON & PERNOLL’S

426 HANDBOOK OF OBSTETRICS AND GYNECOLOGY

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

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.

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

CHAPTER 15

MEDICAL AND SURGICAL COMPLICATIONS DURING PREGNANCY 427

BENSON & PERNOLL’S

428 HANDBOOK OF OBSTETRICS AND GYNECOLOGY

disease is less a problem today than 40 years ago because of better

rheumatic fever prophylaxis, improved health care, and advances

in cardiovascular surgery. Syphilitic carditis has all but disappeared

in pregnancy. Women with collagen disorders (e.g., Marfan’s syn￾drome) or those with prosthetic heart valves are prone to cardiac

problems during pregnancy. Reported incidences of heart disease

vary from 0.5% to 2% of obstetric patients but probably are lower

in the general population because only referral centers are likely to

report their experience. Manifestations of coronary heart disease are

rare during pregnancy. Similarly, pericardial disorders are very in￾frequently seen. Hypertrophic obstructive or nonobstructive car￾diomyopathy in pregnancy is rarely complicated by pregnancy and

delivery.

Heart disease is a major cause of maternal death, but maternal

and perinatal mortality rates are only slightly increased if the dis￾ability is minimal.

FUNCTIONAL CLASSIFICATION

OF HEART DISEASE

For practical purposes, the functional capacity of the heart is the

best single measurement of cardiopulmonary status.

Class I: Ordinary physical activity causes no discomfort.

Class II: Ordinary activity causes discomfort and slight

disability.

Class III: Less than ordinary activity causes discomfort or

disability; patient is barely compensated.

Class IV: Patient decompensated; any physical activity causes

acute distress.

Eighty percent of obstetric patients with heart disease have le￾sions that do not interfere seriously with their activities (classes I

and II) and usually do well. About 85% of deaths ascribed to heart

disease complicating pregnancy occur in patients with class III or

IV lesions (20% of all pregnant patients with heart disease). Nev￾ertheless, much can still be done to improve the prognosis for the

mother and infant in these unfavorable circumstances.

PATHOLOGIC PHYSIOLOGY

The effects of pregnancy on certain circulatory and respiratory func￾tions are reviewed in Chapter 4. Understanding gestational cardio￾vascular and hemodynamic adaptations is key in preventing or man￾aging cardiac complications during pregnancy.