5 min
Your Daily Meds - 3 December, 2021 Your Daily Meds
-
- Education
Good morning and welcome to your Friday dose of Your Daily Meds.
Bonus Review: Can substances pass freely from blood into the CSF?
Answer: Nah. There is a barrier to diffusion of most polar molecules. Naturally, this is called the blood-CSF barrier. In this case, the barrier is due to the tight junctions between the epithelial cells (ependyma) of the choroid plexus. The endothelial cells in the capillaries of the choroid plexus have gaps allowing small molecules to pass between and cross the capillary wall.
Paeds Question:
Which of the following is NOT one of the primary mechanisms by which foetal lung fluid is cleared at the time of birth?
* Reduction of fluid secretion in the lungs
* Expulsion of lung fluid as the foetal chest is compressed during labour
* Lymphatic resorption of lung fluid
* Resorption of lung fluid via capillaries
* Reduced foetal urine output prior to labour
Have a think.
Scroll for the chat.
Case:
A 34-year-old woman, currently at 37 weeks’ gestation in her second pregnancy is reviewed in clinic.
She reports headache, some visual disturbances and epigastric pain, although there has been no vomiting.
On examination, she is hypertensive to 165/115 mmHg, has a tender abdomen worst over the right upper quadrant and is seen to have brisk reflexes.
Which of the following is most suitable to administer given this woman’s clinical presentation?
* Phenytoin
* Sodium valproate
* Magnesium sulphate
* Calcium gluconate
* Cephazolin
Have a think.
Scroll for the chat.
He’s Got Fluid:
The foetal lung acts as a secretory organ prior to birth, with approximately 100-150 mL/kg body weight of fluid being produced in the lungs of the normal foetus. This foetal lung fluid, along with foetal urine, are the primary contributors to amniotic fluid volume. Lung fluid is cleared during the time of birth by several mechanisms, including:
* Reduction of fluid secretion in the lungs
* Expulsion of lung fluid as the foetal chest is compressed during labour
* Resorption of lung fluid via lung interstitium into pulmonary lymphatics and capillaries
Of these, resorption is the main mechanism by which lung fluid is cleared and a failure of this mechanism can lead to transient tachypnoea of the newborn.
So a reduction of foetal urine output prior to labour is not one of the primary mechanisms by which foetal lung fluid is cleared at the time of birth.
Pre-Nasty:
Key to answering this question is recognising the pregnant woman with signs of preeclampsia with severe features.
This is evidenced by headache and visual changes, symptoms of central nervous system dysfunction, epigastric pain and right upper quadrant tenderness, potential signs of hepatic abnormality of HELLP (Haemolysis, Elevated Liver enzymes, Low Platelets) syndrome of severe preeclampsia, and brisk reflexes, potentially foreshadowing the seizures of eclampsia.
Nasty.
Given the features of severe disease in this woman, delivery must occur to minimise the risks of maternal and foetal complications, such as cerebral haemorrhage, hepatic rupture, renal failure, pulmonary oedema, seizure, bleeding of thrombocytopaenia, placental abruption or intra-uterine growth restriction.
Of the options listed, magnesium sulphate is the most appropriate medication to administer as it has been shown to reduce the risk of eclampsia, and may be administered intravenously.
Phenytoin and sodium valproate are other medications used for seizure prophylaxis, but are inferior to magnesium sulphate in this particular obstetric context.
Calcium gluconate may be used to treat magnesium toxicity in the context of seizure prophylaxis with magnesium sulphate.
Cephazolin is used as intrapartum antibiotic therapy in those mothers positive for commensal group B streptococcus infection and hypersensitive to penicillins to prevent neonatal streptococcus disease.
Bonus: What is the difference between the blood-CSF barrier and the blood-brain barrier?
Answer in Monday’s dose.
Closing:
Thank you
Good morning and welcome to your Friday dose of Your Daily Meds.
Bonus Review: Can substances pass freely from blood into the CSF?
Answer: Nah. There is a barrier to diffusion of most polar molecules. Naturally, this is called the blood-CSF barrier. In this case, the barrier is due to the tight junctions between the epithelial cells (ependyma) of the choroid plexus. The endothelial cells in the capillaries of the choroid plexus have gaps allowing small molecules to pass between and cross the capillary wall.
Paeds Question:
Which of the following is NOT one of the primary mechanisms by which foetal lung fluid is cleared at the time of birth?
* Reduction of fluid secretion in the lungs
* Expulsion of lung fluid as the foetal chest is compressed during labour
* Lymphatic resorption of lung fluid
* Resorption of lung fluid via capillaries
* Reduced foetal urine output prior to labour
Have a think.
Scroll for the chat.
Case:
A 34-year-old woman, currently at 37 weeks’ gestation in her second pregnancy is reviewed in clinic.
She reports headache, some visual disturbances and epigastric pain, although there has been no vomiting.
On examination, she is hypertensive to 165/115 mmHg, has a tender abdomen worst over the right upper quadrant and is seen to have brisk reflexes.
Which of the following is most suitable to administer given this woman’s clinical presentation?
* Phenytoin
* Sodium valproate
* Magnesium sulphate
* Calcium gluconate
* Cephazolin
Have a think.
Scroll for the chat.
He’s Got Fluid:
The foetal lung acts as a secretory organ prior to birth, with approximately 100-150 mL/kg body weight of fluid being produced in the lungs of the normal foetus. This foetal lung fluid, along with foetal urine, are the primary contributors to amniotic fluid volume. Lung fluid is cleared during the time of birth by several mechanisms, including:
* Reduction of fluid secretion in the lungs
* Expulsion of lung fluid as the foetal chest is compressed during labour
* Resorption of lung fluid via lung interstitium into pulmonary lymphatics and capillaries
Of these, resorption is the main mechanism by which lung fluid is cleared and a failure of this mechanism can lead to transient tachypnoea of the newborn.
So a reduction of foetal urine output prior to labour is not one of the primary mechanisms by which foetal lung fluid is cleared at the time of birth.
Pre-Nasty:
Key to answering this question is recognising the pregnant woman with signs of preeclampsia with severe features.
This is evidenced by headache and visual changes, symptoms of central nervous system dysfunction, epigastric pain and right upper quadrant tenderness, potential signs of hepatic abnormality of HELLP (Haemolysis, Elevated Liver enzymes, Low Platelets) syndrome of severe preeclampsia, and brisk reflexes, potentially foreshadowing the seizures of eclampsia.
Nasty.
Given the features of severe disease in this woman, delivery must occur to minimise the risks of maternal and foetal complications, such as cerebral haemorrhage, hepatic rupture, renal failure, pulmonary oedema, seizure, bleeding of thrombocytopaenia, placental abruption or intra-uterine growth restriction.
Of the options listed, magnesium sulphate is the most appropriate medication to administer as it has been shown to reduce the risk of eclampsia, and may be administered intravenously.
Phenytoin and sodium valproate are other medications used for seizure prophylaxis, but are inferior to magnesium sulphate in this particular obstetric context.
Calcium gluconate may be used to treat magnesium toxicity in the context of seizure prophylaxis with magnesium sulphate.
Cephazolin is used as intrapartum antibiotic therapy in those mothers positive for commensal group B streptococcus infection and hypersensitive to penicillins to prevent neonatal streptococcus disease.
Bonus: What is the difference between the blood-CSF barrier and the blood-brain barrier?
Answer in Monday’s dose.
Closing:
Thank you
5 min