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## Cardiac Output, Stroke Volume, and Heart Rate In order to understand the hemodynamics of infants and children, it's important to understand the relationships among cardiac output (CO), heart rate (HR), and stroke volume (SV) as the child grows and cardiac size increases: - **Newborn:** - CO...

## Cardiac Output, Stroke Volume, and Heart Rate In order to understand the hemodynamics of infants and children, it's important to understand the relationships among cardiac output (CO), heart rate (HR), and stroke volume (SV) as the child grows and cardiac size increases: - **Newborn:** - CO - 800/mL/min - SV - 5 ml. - HR - 145 - **6 months:** - CO - 1000-1600 mL/min - SV - 10 ml. - HR - 120 - **12 months:** - CO - 1400 mL/min - SV - 13 ml. - HR - 115 - **4 years:** - CO - 2300 ml./min - SV - 26 ml. - HR - 105 - **8 years:** - CO - 3500 mL/min - SV - 42 mL. - HR - 83 - **10 years:** - CO - 4000 mL/min - SV - 50 mL - HR - 75 - **15 years (adult levels)** - CO - 5000 to 6000 ml./min - SV - 85 mL - HR - 70 ## Pulse Oximetry Pulse oximetry, continuous or intermittent, utilizes an external oximeter that attaches to the child's foot, toe, or finger (depending on age) to indirectly estimate arterial oxygen saturation (SPO2), the percentage of hemoglobin that is saturated with oxygen. The oximeter also usually attaches to a machine that emits a beep with each heartbeat and indicates the current heart rate and BP. The oximeter uses light waves to determine oxygen saturation (SPO2). Oxygen saturation should be maintained >95% although some patients with cardiovascular or pulmonary disorders may have lower SPO2. Results may be compromised by impaired circulation, excessive light, poor positioning, and fingernail polish. If SPO2 falls, the oximeter should be repositioned, as incorrect position is a common cause of inaccurate readings. Oximetry is often used post-surgically and when patients are on mechanical ventilation. Oximeters do not provide information about carbon dioxide levels and