What is the pathophysiology of variable decelerations?

What is the pathophysiology of variable decelerations?

Variable decelerations can be seen resulting from fetal movement if the fetus is premature. [4] In the term fetus, variable decelerations result from vagus nerve-mediated parasympathetic effects on the heart. There are several theories regarding the pathway that leads to this vagal stimulation.

What is the cause of variable decelerations?

Common causes of variable decelerations include vagal reflex triggered by head compression during pushing and cord compression such as that caused by short cord, nuchal cord, body entanglement, prolapsed cord, decreased amniotic fluid, and fetal descent.

What are the features of variable decelerations?

* Regard the following as concerning characteristics of variable decelerations: lasting more than 60 seconds; reduced baseline variability within the deceleration; failure to return to baseline; biphasic (W) shape; no shouldering.

What is a variable deceleration definition?

Variable deceleration. An abrupt* decrease in FHR below the baseline. The decrease is ≥15 bpm, lasting ≥15 secs and <2 minutes from onset to return to baseline. The onset, depth, and duration of variable decelerations commonly vary with successive uterine contractions.

What are recurrent variable decelerations?

Recurrent decelerations ( variable, early, or late ): Decelerations occur with > 50% of uterine contractions in any 20 minute segment. Prolonged deceleration : A decrease in FHR of > 15 beats per minute measured from the most recently determined baseline rate.

Which characteristics describe early decelerations?

Early decelerations in the FHR are associated with head compression as the fetus descends into the maternal pelvic outlet; they are not generally a concern during normal labor. An FHR finding of 126 beats per minute is normal and not a concern.

What do you do for variable decelerations?

Some nursing interventions include: turn mom onto her side, stop Picotin if infusing, administer 10 L of O2, maintain IV access, determine the Fetal Heart Rate variability, and contact doctor.

How do you read a Cardiotocography?

To interpret a CTG you need a structured method of assessing its various characteristics….The most popular structure can be remembered using the acronym DR C BRAVADO:

1. DR: Define risk.
2. C: Contractions.
3. BRa: Baseline rate.
4. V: Variability.
5. A: Accelerations.
6. D: Decelerations.
7. O: Overall impression.

What does marked variability indicate?

Marked variability in the baseline FHR is present when the amplitude exceeds 25 BPM. This pattern (sometimes called a saltatory pattern) suggests acute hypoxia or mechanical compression of the umbilical cord and is often seen during the second stage of labor.

What causes decreased variability?

Etiologies of decreased variability: Fetal metabolic acidosis [7], CNS depressants[8,9], fetal sleep cycles[10], congenital anomalies, prematurity [11,12], fetal tachycardia, preexisting neurologic abnormality [13], normal [14], betamethasone[15].

What do early decelerations mean?

Early deceleration is defined as a symmetrical decrease and return of fetal heart rate (FHR) that is associated with a uterine contraction.

What is the priority nursing intervention for recurrent variable decelerations?

Variable Decelerations Repositioning of the mother can relieve this compression if it is minor. However, if these decelerations continue, it could be a sign of more serious cord compression, and the nurse should administer oxygen, stop Oxytocin (Pitocin) if applicable, and check for vaginal cord prolapse.

What are the physiologic mechanisms of variable decelerations?

The physiologic mechanisms of variable decelerations †. The vagal reflex produced is probably caused by a combination of chemoreflex (earlier in the deceleration) and baroreflex (later). The variable deceleration is accompanied by an acidosis, primarily respiratory, and probably hypoxemia. Cord compression results in decreased umbilical blood flow.

What are the effects of intermittent variable decelerations?

Intermittent variable decelerations are usually benign and do not result in poor perinatal outcomes. Recurrent variable decelerations correlate with poor outcomes, including neonatal acidemia. The peripheral chemoreflex response to hypoxemia is a tailored response, so an increasing severity of hypoxemia leads to deeper decelerations.

What was the purpose of the variable deceleration study?

The physiologic mechanisms of variable decelerations Robert H. Ball, MD, and Julian T. Parer, MD, PhD San Francisco, California OBJECTIVES: The purpose of this study was to determine the cause and physiologic consequences of variable decelerations.

How is a variable deceleration related to contractions?

Early and late decelerations have some time schedule with contractions. However, variable accelerations may or may not be related to contractions. In order to be characterized as a variable deceleration, the decrease in the fetal heart rate must be at least 15 beats per minute (bpm) lower than the baseline heart rate.