>RCP – Gravidology for the Emergency Physician

Gravidology for the Emergency Physician

Resident Clinical Pearl – April 2017

Luke Taylor, PGY1 iFMEM, Dalhousie University, Saint John, New Brunswick

Reviewed by Dr. David Lewis

 

 

Many adaptations take place in the gravid female, the end goal of each being to provide optimal growth for the fetus, as well as to protect the mother from the potential risks of labour and delivery. It is very important to understand these changes when assessing an unwell pregnant patient in the ED.


Vital Signs:

 

BP: Blood pressure falls earlier in pregnancy with nadir in second trimester (mean ~105/60 mmHg). In the third trimester BP increases and may reach pre pregnancy levels at term. BP is related to a reduction in SVR and multiple hormonal influences that are not fully understood.

 

HR: CO=HRxSV. The increase in CO is attributed mainly to the increase in circulating volume (30-50% above baseline). HR increases by 15-20 beats/min over non pregnant females.

*Supine position in the gravid female can lower CO by 20-30% due to a reduction in venous return which reduces stroke volume.

 

RR: State of relative hyperventilation. NO change in RR, however there is an increase in tidal volume resulting in a 50% increase in minute ventilation. Increased O2 consumption and demand with hypersensitivity to chances in CO2.

*60-70% of women experience a sensation of dyspnea during pregnancy

 

 


Diagnostic Imaging and ECG:

 

Must ensure imaging is necessary for management and explain risks well.

** 1 rad increases the risk of childhood malignancy by 1.5-2x above baseline.

 

CXR: Minimal changes to CXR in normal pregnancy but may have; prominence of the pulmonary vasculature and elevation of the diaphragm.

 

PoCUS: FAST doesn’t perform well in pregnant patient. Small amount of physiologic free fluid in the pelvis (posterior, lower portion of uterus), all else should be considered pathologic. Physiologic hydronephrosis and hydroureter (mostly R-sided).

 

CT-A: When required to r/o PE, capable of being completed at very low rad (below teratogen cut off, CT of 1-3rad is under the teratogenic cutoff of 5-10rad = 10,000 cxr or 10x CT chest

 

ECG: Various changes occur, may include ST and T wave changes, and presence of Q waves. The heart is rotated toward the left, resulting in a 15 to 20º left axis deviation. Marked variation in chamber volumes, especially left atrial enlargement. This can lead to stretching of the cardiac conduction pathways and predisposes to alterations in cardiac rhythm.

 

 


Routine Laboratory Tests:

 

CBC: Physiologic Anemia – Increased retention of Na and H2O (6-8L) leading to volume expansion combined with a slightly smaller increase in red cell mass.

Leukocytosis – Due to physiologic stress from the pregnancy itself, creates a new reference range from 9000, to as high as 25000 in healthy pregnant females (often predominately neutrophils)

 

PTT: Various processes result in 20% reduction of PTT and a hypercoagulable state (also helps to protect from hemorrhage during labour).

 

Urinalysis: Very common to have 1-3+ leukocytes, presence of blood, as well as ketones on point of care testing. Not considered pathologic unless Nitrite positive.

 

Creatinine: Pre-eclamptic patients may have a creatinine in the normal range, but have a drastic reduction in GFR (40%).

 

B-HCG: Every female of childbearing years should be considered to: Be pregnant, RH-, and have an ectopic until proven otherwise. Draw a beta HCG on every critically ill or injured women of childbearing years regardless of reported LMP.

 


ACLS:

 

Remember, most features are the same as when resuscitating a non-pregnant patient.

Some things to remember:

 

Higher risk of aspiration – Progesterone relaxes gastroesophageal sphincters and prolongs transit times throughout the intestinal tract. = Careful bag mask ventilation, do not overdo it.

Left uterine displacement (LUD)– While patient supine to provide best chest compressions possible

Medications and Dosages– Remain the same in pregnancy, vasopressors like epinephrine should still be used despite effect on uterus perfusion

Defibrillation OK-  Fetus is not effected by defibrillation, low risk of arc if fetal monitors in place, do not delay.

Four minute rule– For patients whose uterus is at or above the umbilicus, prepare for cesarean delivery if no ROSC by 4mins. ** In a case series of 38 perimortem cesarean delivery (PMCDs), 12 of 20 women for whom maternal outcome was recorded had ROSC immediately after delivery.

Etiology:  Must continue to think broadly, however common reasons for maternal cardiac arrest are: bleeding, heart failure, amniotic fluid embolism (AFE), and sepsis. Common maternal conditions that can lead to cardiac arrest are: preeclampsia/eclampsia, cerebrovascular events, complications from anesthesia, and thrombosis/thromboembolism.

 


REFERENCES

Cardiac Arrest in Pregnancy – A Scientific Statement From the American Heart Association

Up To Date – Respiratory Tract Changes in Pregnancy

Merk Manual – Physiology of Preganacy

https://radiopaedia.org/cases/chest-x-ray-in-normal-pregnancy