Book of Medical Disorders in Pregnancy - Tintash

hours. The maximal effect takes 36 to 72
hours to develop, after initial
administration of the drug.
The clinical target in achieving
desired anticoagulant effect is to reduce
the prothrombin time or activity to about
20 per cent of normal control The effect
of these drugs can be reversed by
intravenous injection of 50 to 150 mg of
Vitamin K" given very slowly and no
more than 10 mg per minute. The
activity of Vitamin K dependent clotting
factors reaches to safe level within 4 to 8
hours. Oral anticoagulants cross the
placenta and may cause serious bleeding.
Warfarin is preferred over other
agents since it produce less side effects.
The initial dose is around 35 to 40 mg
followed by 10 mg, depending upon the
prothrombin time.
Fig 10.4: Shows embolism in place in
one of the lungs
Pulmonary embolism is the
second most common cause of maternal
death in pregnancy. This occurs when a
thrombus breaks free from the vein. It
enters into the pulmonary artery at the
141
time of right ventricular systole,
becomes impacted in its branch whose
lumen is narrow and the thrombus
cannot pass through it. The effect of the
embolism on the patient depends upon
the size of the embolus. The clinical
symptoms may be delayed until the
fourth or fifth week after delivery, when
the patient has returned home.
Etiology: The causes of pulmonary
embolism are the same as for deep
venous phlebothrombosis. Pulmonary
embolism is a recurrent disease. The
woman who has cine attack is liable to
have another within a few hours or day.
Pathology: Embolism can occur before
there is any sign of venous thrombosis.
Pulmonary infarction occurs when a
large clot is lodged in one of the main
branches of the pulmonary artery. This
clot comes from the femoral or iliac vein
in majority of cases, but in few cases it
may come from the pelvic veins.
The emulous can be lethal if half
of the lung capacity is affected, An
immense spasm of the unblocked
pulmonary arteries play an important
role in producing this fatal effect. Small
emboli do not produce infarction of
healthy lungs, therefore they go
unnoticed and the student may confuse
the clinical features with pleurisy or
pneumonia. However, multiple and
recurrent small emboli can result in
pulmonary hypertension if left untreated.
Pathophysiology of infraction:
The emboli can stop venous flow
from the pulmonary segment supplied by
these vessels. The alveoli continue to be
no rushed by the bronchial arteries
which carry oxygenated blood.