With respect to pregnancy,

a)  indicate how the following variables change in the third trimester (either increase or decrease or no change)

Variable

Direction of change

Systolic blood pressure

 

Diastolic blood pressure

 

Heart rate

 

Blood volume

 

Haematocrit

 

Tidal volume

 

pH

 

PCO2

PO2

Bicarbonate

b)  List 4 conditions specific to pregnancy which may result in right or left heart failure or both.

c) Outline the major differences in approach to cardiopulmonary resuscitation in pregnancy as compared to the non pregnant adult.

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College Answer

a)  indicate how the following variables change in the third trimester (either increase or decrease or no change)

Variable

Direction of change

Systolic blood pressure

Decrease

Diastolic blood pressure

Decrease

Heart rate

Increase

Blood volume

Increase

Haematocrit

Mild decrease

Tidal volume

Increase

pH

No change

PCO2

Decrease

PO2

Increase

Bicarbonate

Decrease

b)  List 4 conditions specific to pregnancy which may result in right or left heart failure or both.

Peripartum cardiomyopathy Pulmonary thromboembolism Amniotic fluid embolism Preclampsia
Tocolytic pulmonary oedema

c) Outline the major differences in approach to cardiopulmonary resuscitation in pregnancy as compared to the non pregnant adult.

1) CPR in left lateral position
2) Consideration of emergency Caesar

Discussion

This question closely resembles Question 16 from the second paper of 2010.

In summary:

a)

Question a) specifically refers to Table 64.1 on page 685. A summary of the normal physiological changes in pregnancy can be found elsewhere.

b) is perfect as a list. Amniotic fluid embolism actually causes right heart failure at first, and then turns into LV failure. In fact, it would be even more perfect as a table:

This works best as a table. In fact, in Sliwa et al (2010) there is an even better table (Table 3. p.772)

Left-dominant Right-dominant
  • Pre-eclampsia
  • Eclampsia
  • Tocolytic therapy
  • Peripartum cardiomyopathy
  • Pituitary apoplexy
    (Sheehan's syndrome)
  • Worsening of pre-existing
    rheumatic MR
  • Pre-existing idiopathic dilated cardiomyopathy (IDC) unmasked by pregnancy
  • Massive PE
  • Aminotic fluid embolism
  • Worsening of pre-existing rheumatic TR

Potentially bi-ventricular:

  • Pre-existing unrecognized congenital heart disease
  • Pregnancy-associated myocardial infarction

c) is well discussed in the chapter on cardiac arrest in the pregnant patient. In short:

Keep in mind the following alternative causes of arrest:

  • Amniotic fluid embolism
  • Hypertensive disorder of pregnancy (with ensuing cardiac failure)
  • Seizures (with ensuing hypoxia and arrest)
  • Haemorrhage from liver rupture
  • Haemorrhage from uterine rupture

Issues which complicate the pregnant arrest and peri-arrest scenario:

  • Difficult intubation
  • Increased risk of aspiration (the stomach just doent't empty)
  • Venous return is impaired by the gravid uterus
  • Systemic oxygen consumption is increased
  • Cardiac output and circulating volume are greater; decompensation occurs later.

Manually displace the uterus to the left (off the aorta and vena cava)

  • Manually displace the uterus to the left (off the aorta and vena cava)
  • Add a left lateral tilt (the ideal angle is unknown, and is thought to be between 15° and 30°)
  • Biaxillary defibrillator pad placement
  • Prepare for an emergency perimortem caesarian.

To the college answer  I might add that the emergency caesarian should be considered after 4 minutes of CPR, as per the ILCOR guidelines. The weirdly specific 27° pelvis tilt mentioned by the college can get you reaching for a protractor. It probably comes from the old AHA guidelines (these days the guideline-makers for the ECC and AHA no longer recommend the left lateral tilt (see the 2015 AHA update and the 2015 ECC guidelines).A left lateral tilt may compromise effective CPR, but is still recommended by the ARC Guideline 11.10  (2011) "Special Circumstances". Presumably, once the ARC get around to it, their guidelines will fall in line with international consensus. The 27° figure comes from Rees and Willis (1998), who got physicians to perform CPR on specially modified mannequins at different degrees of tilt. The authors found that the 27 degrees was the  angle at which safe positioning and compression efficacy were at optimal compromise. Chest compression force was not too badly affected (80% of the force of compressions with the patient in a supine position), and the patient was unlikely to roll off the bed at this angle.

References

References

Einav, Sharon, Nechama Kaufman, and Hen Y. Sela. "Maternal cardiac arrest and perimortem caesarean delivery: evidence or expert-based?." Resuscitation 83.10 (2012): 1191-1200.

Morris Jr, John A., et al. "Infant survival after cesarean section for trauma." Annals of surgery 223.5 (1996): 481.

Beckett, V. A., P. Sharpe, and M. Knight. "CAPS—A UKOSS STUDY OF CARDIAC ARREST IN PREGNANCY AND THE USE OF PERI-MORTEM CAESAREAN SECTION. IMPLICATIONS FOR THE EMERGENCY DEPARTMENT." Emergency Medicine Journal 32.12 (2015): 995-995.

Elkady, A. A. "Peri-mortem Caesarean Section Delivery: A Literature Review and Comprehensive Overview." Enliven: Gynecol Obstet 2.3 (2015): 005.

Campbell, Tabitha A., and Tracy G. Sanson. "Cardiac arrest and pregnancy." Journal of emergencies, trauma, and shock 2.1 (2009): 34.

Katz, Vern L., Deborah J. Dotters, and William Droegemueller. "Perimortem cesarean delivery." Obstetrics & Gynecology 68.4 (1986): 571-576.

Manner, Richard L. "Court-Ordered Surgery for the Protection of a Viable Fetus:, 247 6a. 8b, 274 SE 2d 457 (1981)." (1982).