Page 25 - Journal of Special Operations Medicine - Spring 2016

Case 5: Healthy Woman During Active Labor one dose of epinephrine via the endotracheal tube. He
A healthy, normotensive (baseline BP, 115/75mmHg), was transported to a nearby Level I adult trauma cen-
34-year-old woman (71.67kg, 157.5cm) was admitted ter, where chest compressions were continued and a
to labor and delivery at 37.9 weeks’ gestation of her first DataOx device was applied to the patient’s index finger,
child. CRI measures were continuously recorded and revealing a CRI of 0.75 with active cardiopulmonary
averaged over approximately 10-minute periods (Figure resuscitation (CPR). CPR was briefly halted when the
5). The patient’s baseline average CRI was 0.83 and re- patient was transferred from the medics’ stretcher to a
mained at 0.83 after she received an epidural anesthetic gurney in the trauma bay. Since CRI is calculated in a
at around 137 minutes. She began active labor at 257 beat-to-beat fashion using a sliding 30-beat window,
minutes. After the onset of active labor, CRI showed an anticipated drop of CPR to 0 during approximately
slight elevation as the patient experienced more frequent 10 seconds of chest compression termination (i.e., no
and intense contractions. At 365 minutes, the patient perfusing rhythm) was buffered by previous CRI values,
experienced a 5-minute uterine contraction associated resulting in a transient drop in CRI to a low of 0.55.
with a reduction in CRI from 0.82 to 0.76. Immediately CRI returned to approximately 0.75 with continued ac-
following IV administration of 0.25mg terbutaline (a tive compressions (Figure 6). A FAST examination con-
β -adrenergic receptor agonist) as a tocolytic, the pa- firmed no cardiac activity. The patient was pronounced
2
tient’s HR increased (Figure 5, top panel); coincident BP dead within 5 minutes of arrival, and the DataOx device
fluctuations were between hypertensive (approximately was then removed. Unfortunately, when the patient was
130/75mmHg) and baseline levels. With terbutaline pronounced dead and CPR stopped, the data collection
administration, CRI initially decreased to 0.38 and re- device was immediately removed, preventing the dem-
mained low (>0.4) for the following 150 minutes. After onstration of CRI to 0.
4 hours of active pushing, the patient delivered a viable
male infant (3.38kg) via vaginal birth at 772 minutes, Figure 6 Continuous Compensatory Reserve Index values
with an estimated blood loss of 250mL. The CRI re- during 2.25 minutes of CPR in an asystolic man with a self-
turned to >0.7 as the patient recovered and underwent inflicted gunshot wound to the chest.
repair of a second-degree perineal laceration. There was
no postpartum hemorrhage or further complications.

Figure 5 Heart rate (top) and compensatory reserve (bottom)
measured during approximately 7 hours of labor.

CPR, cardiopulmonary resuscitation.

Case 7: Subject With Postural Orthostatic
Tachycardia Syndrome
The CRI was measured during a stand-to-supine dem-
onstration conducted on a 16-year-old girl who had
developed postural orthostatic tachycardia syndrome
Each bar represents approximately 10 minutes. Bar colors: green, Com- (POTS) 6 years earlier. Figure 7 shows her continuously
pensatory Reserve Index (CRI) >0.6; and yellow, CRI ≤0.6 and >0.3.
recorded HR (upper panel) and CRIs (lower panel). She
demonstrated a typical tachycardic response (average
Case 6: Patient Receiving HR, 120–125 bpm) when she was asked to stand qui-
Cardiopulmonary Resuscitation etly; her average CRI was 0.17. At 3 minutes, the subject
A 57-year-old man sustained a self-inflicted gunshot was instructed to assume a supine posture. Within 30
wound to the anterior chest. Medics arrived on scene seconds, the subject became clinically “normal,” with
within minutes and found the patient comatose (Glasgow an HR of 60 bpm and CRI >0.8. After 2.5 minutes in
Coma Scale score, 3) and asystolic. Chest compressions the supine posture, the subject stood up, resulting in im-
were initiated, and the patient was intubated and given mediate tachycardia and a drop in her CRI to nearly 0.2.

Machine Learning and Hemodynamic Instability 9