The question "What is the normal range of CPR?" is unclear. CPR typically refers to cardiopulmonary resuscitation, a procedure performed in emergencies, and doesn't have a "normal range" in the way a medical test result might. However, if the question is about the cardiotocography pulsatility ratio (CPR) used in assessing fetal well-being, then we can discuss thresholds used to identify abnormal values. It's important to note that CPR in this context is a ratio used during fetal monitoring, not the emergency procedure of cardiopulmonary resuscitation. This response assumes the query concerns cardiotocography pulsatility ratio (CPR) in fetal monitoring.
Understanding the Cardiotocography Pulsatility Ratio (CPR)
The cardiotocography pulsatility ratio (CPR) is used to evaluate blood flow in the fetus. It's calculated using Doppler ultrasound to measure blood flow in the umbilical artery and middle cerebral artery. An abnormal CPR might indicate fetal distress.
Defining Abnormal CPR Thresholds
Various studies have different definitions for what constitutes an abnormal CPR. The reference indicates:
- Ratio <1
- Ratio <1.08
These are used in terms of multiples of the median (MoM) or based on centiles. Therefore, we cannot define a normal CPR range without knowing more about the specific study's parameters.
Factors Affecting Interpretation
- Gestational Age: Normal values for Doppler studies, including CPR, can change with gestational age.
- Underlying Conditions: Maternal conditions (e.g., hypertension, diabetes) can influence fetal blood flow and CPR values.
