This is a prospective, single-arm, non-randomized, non-controlled single-center study for the evaluation of the Zynex CM-1600 in 20 healthy adults undergoing a manual blood loss of up to 500mL followed by an infusion of 1 liter of normal saline.

Inclusion Criteria:

• Participant must have the ability to understand the parameters of participation and provide written informed consent
• Male or female of any race
• Participant is adult 18 or older
• Participant must be willing and able to comply with study procedures and duration
• In the Principal Investigator's medical judgment, the participant is suitable for a blood draw of up to 500mL
• Participant must weigh at least 110 pounds

Exclusion Criteria:

• Any upper extremity amputation

• Females who are pregnant, who are trying to get pregnant, or have a urine test positive for pregnancy on the day of the study

• Participant has a heart condition that may interfere with the Zynex CM-1600 (e.g., pacemakers, defibrillator, irregular heartbeat, dextrocardia, etc.)

• Participant has been diagnosed with chronic fatigue syndrome (also known as chronic fatigue, immune dysfunction syndrome, or myalgic encephalomyelitis)

• Participant requires equipment and/or devices that may interfere with the Zynex CM-1600 (e.g., life-sustaining equipment, other monitoring devices, insulin pumps, or other implanted devices)

• Participant is taking coumadin (warfarin), heparin, or other prescription blood thinners for 7 or more days prior to blood draw

• Participant donated blood within 8 weeks prior to the study blood draw

• Participant has high or low blood pressure on the day of blood draw (high blood pressure is defined as systolic > 180 mmHg or diastolic > 100 mmHg; low blood pressure is defined as systolic < 100 mmHg or diastolic < 60 mmHg)

• Participant has symptoms of an active infection or a temperature ≥ 100 °F

• Female with hemoglobin levels of less than 12.1g/dL or male with hemoglobin levels of less than 13.8g/dL

• Participants with self-reported heart or cardiovascular conditions such as:

  • History of cardiovascular surgery
  • History of chest pain (angina)
  • Heart rhythms other than a normal sinus rhythm or respiratory sinus arrhythmia
  • History heart attack/myocardial infarction
  • Peripheral arterial disease
  • Carotid artery disease
  • Unexplained shortness of breath
  • Congestive heart failure (CHF)
  • History of stroke/transient ischemic attack
  • Myocardial ischemia
  • Cardiomyopathy
  • Dextrocardia

• Participants with clotting disorders such as:

  • Hemophilia
  • History of blood clots
  • History of bleeding problems
  • Bruises easily

• Self-reported health conditions as identified in the Health Assessment Form including:

  • Diabetes
  • Uncontrolled thyroid disease
  • Kidney disease / chronic renal impairment
  • History of seizures (except childhood febrile seizures)
  • Epilepsy
  • History of unexplained syncope
  • Recent history of frequent migraine headache within the last 2 months
  • Recent head injury within the last 2 months
  • History of cancer, with or without chemotherapy within the last 2 months

• Other known health conditions deemed unsuitable for participation by the PI when considered upon disclosure on health assessment form

Adverse events were collected during subject participation in the study and for 24hrs following (e.g., up to 48hrs)