Book 4, case 1-Sickle cell and obstetrics Flashcards
Why do patients with sickle cell take hydroxyurea?
administered to reduce the number of sickle cell
crises via its ability to increase circulating fetal hemoglobin, which, in turn, reduces
the rate and extent of HbS sickling.
Pathophys of sickle cell:
Valine for glutamic acid in beta chains of hgb=HGb s. Hgb s molecules can polymerize making a sickled shape=hemolyiss and ischemic end organ injury
Why doesn’t sickling happen always in venous blood?
Even though HbS starts to polymerize at PO2 of 50 mmHg, this is time dependent-it transitions to lungs where oxygenation reverses that.
What is aplastic crisis? How do you treat it?
bone marrow suppression secondary to
infection (typically Parvovirus B 19) or folate deficiency leads to decreased red blood
cell production leading to a profound anemia. Treatment: correction of folate deficiency and admin of blood until bone marrow suppression resolves (4-7 days)
EValuation of sickle cell pt and a pregnant sickle cell pt at that:
Full H&P Questions about frequency of crisis INquire about hx of acute chestsyndrome Examine for signs of infxn evaluate volume status if SOB: CXR
What is an exchange transfusion, and would you do it in preggo sickle cell pts?
The procedure involves slowly removing the person’s blood and replacing it with fresh donor blood or plasma-nah, I wouldjust give a transfusion of leukocyte reduced hemoglobin S free red blood cells to achieve a Hct of 30% (leukocyte reduced)
If pt has low plt (82k for example) but is huge and possible difficult airway-and you wanna do regional-what are you going to do to prepare-exam wise?
I would evaluate the patient for signs of coagulopathy (bruising,
mucosal bleeding, bleeding at IV sites), make sure that there was not an unacceptable
downward trend in her platelet level, and judiciously provide fluids for volume
replacement (overaggressive fluid administration risks pulmonary and cerebral edema
in the setting of severe preeclampsia).
Postoperatively, I would ensure adequate platelet levels and allow for complete
resolution of motor and sensory function prior to removing the neuraxial catheter (to
allow for better detection of the change in motor or sensory function associated with
epidural or spinal hematoma formation). Following the removal of the catheter, I
would order hourly neuro-checks for 12 hours, to more quickly identify the signs and
symptoms of epidural or spinal hematoma
Shortly after achieving adequate levels with the epidural, the case begins and the
baby is quickly delivered. A few minutes after delivery, the mother complains of
difficulty breathing and then begins seizing. What do you think is going on?
The timing of her dyspnea and seizure, occurring shortly after delivery
of the baby, is consistent with amniotic fluid embolism. However, I would also
consider that her symptomatology might be the result of local anesthetic toxicity (this
possibility should be considered in any situation where a patient experiences an
altered mental state, neurologic symptoms, or cardiovascular instability following the
administration oflocal anesthetic for regional anesthesia), preeclampsia/eclampsia
(the increased capillary permeability associated with preeclampsia could lead to
pulmonary edema and dyspnea), or her sickle cell disease (vaso-occlusive crisis can
lead to dyspnea and/or seizures).
Signs and symptoms of amniotic fluid embolism?
The first or early phase consists of pulmonary hypertension (secondary to
pulmonary vasospasm), hypotension (secondary to right heart failure), hypoxia
(secondary to ventilation-perfusion mismatching), seizure, and cardiac arrest. For
those who survive the first phase, the second phase consists of left ventricular failure
IF you have to leave the catheter for a long time for some reason:
I would ensure that a sterile occlusive dressing
was placed over the catheter insertion site and assess the patient daily for signs or
symptoms of infection, such as fever, backache, headache, erythema, and tenderness
over the insertion site.
Nitrous oxide in sickle cell pt who recently had eye surgery:
So if you can’t supplement with nitrous in uterine atony, then what:
How long to avoid nitrous after eye surgery? How long to avoid nitrous after the other eye stuff?
NO.I would want to continue administering 100% oxygen to minimize the
amount of deoxygenated hemoglobin S, thereby reducing the risk of significant
sickling.
Secondly,this very soluble gas could result in the expansion of the intra-vitreal
bubble, leading to increased intra-ocular pressure, central retinal artery occlusion, and
retinal and/or optic nerve ischemia.
If you cant’ supplement with nitrous in uterine atony-reduce inhalational agent to less than 0.5%, administer 100% O2 and supplement with narcotics
Avoid nitrous for 7-45 days after eye surgery
Particularly dangerous with sulfur hexafluoride and perfluoropropane
Avoid for 15 minutes before intraocular gas
Avoid for 7-10 days after sulfur hexafluoride
Avoid for at least a month after perfluoropropane
What makes you nervous about nitrous post eye surgeries? Would you feel okay if the surgeon had used air?
B/c we are worried about nitrous oxide expansion of an intra-ocular bubble.
Nitrous oxide should be discontinued 15 minutes prior to the injection of intra-
vitreal gas for retinal detachment surgery.
Nitrous should be avoided for a variable amount of time depending on the type of
gas injected:
o Air - avoid nitrous oxide for 5 days
o Sulfur Hexafluoride - avoid nitrous oxide for 10 days
o Perfluoropropane - avoid nitrous oxide for at least 30 days
Is sickle cell disease associated with pulmonary hypertension?
YES
Bleeding continues and you institute the massive blood transfusion protocol.
You have given 5 units of PRBCs and 4 units of FFP. The patient’s blood
pressure drops to 78/44 mmHg and is not responsive to additional doses of
phenylephrine. What do you think is going on?
The most likely causes of her nonresponsive hypotension are
inadequate blood or fluid replacement and/or hypocalcemia secondary to massive
blood transfusion (the citrate preservative in blood products can chelate calcium
during massive blood transfusion). However, I would also be considering other
potential causative or contributory factors, such as: ( 1) myocardial depression from
acidosis or anesthesia; (2) magnesium toxicity (vasodilation and myocardial
depression); (3) right heart failure due to the pulmonary hypertension associated with
sickle cell lung disease; (4) transfusion reaction; and (5) pulmonary
thromboembolism.
Signs of citrate intoxication:
increased
central venous pressure, narrow pulse pressure, prolonged QT interval, flattened T
waves, widened QRS complexes, and increased intraventricular end-diastolic
pressure.