Masimo Rainbow SET(®) Radical-7 “Pulse CO-Oximeter” Accurately Measures COHb When SaO2 Greater Than 85%

Carbon Monoxide (CO) is a gas produced by the combustion of carbon-containing fuels or the inadequate ventilation of natural gas. Once CO is in the bloodstream with a strong bond with hemoglobin, it prevents oxygen from reaching tissues. CO by itself is undetectable by humans, but is often suspected when car exhaust is smelled or when mercaptan is smelled in a natural gas leak.

Exposure to CO is the leading cause of death by poisoning in industrialized countries, and is more likely to go undetected in the case of a malfunctioning furnace or in the case of a failed ventilation system. Still, the CO poisoning presents a constellation of symptoms that mimic other illnesses. As a result, as many as half of all patients with CO illness may be misdiagnosed when presenting to emergency departments — delaying treatment and even returning vulnerable patients and their families to potentially lethal environments. Patients with prolonged and untreated CO exposure have long-term side effects and increased risk for cardiac complications. If untreated, CO exposure may damage the cardiac, neurological, metabolic, pulmonary and renal systems of the body.

The Masimo Rainbow SET(®) Radical-7 “pulse CO-oximeter” uses multiwavelength technology to obtain carboxyhemoglobin (COHb) levels in the blood that previously required blood sampling and laboratory analysis. Innovative noninvasive sensor technology uses more than 7 wavelengths of light to acquire blood constituent data based on light absorption. Advanced signal processing algorithms and unique adaptive filters work together to isolate, identify and quantify various hemoglobin species. Blood measurement results are then displayed numerically.

The Masimo Rainbow SET(®) Radical-7 “pulse CO-oximeter” measures:

Total Hemoglobin (SpHb®)
Oxygen Content (SpOC™)
Carboxyhemoglobin (SpCO®)
Methemoglobin (SpMet®)
Plus: Masimo SET measurements of Oxygen Saturation (SpO2), Pulse Rate (PR), Perfusion Index (PI), and Pleth Variability Index (PVI®)

Researchers in October 2013 published a research study on the accuracy of the Masimo Rainbow SET(®) Radical-7 “pulse CO-oximeter in the medical journal Anesthesia & Analgesia. Twelve healthy, nonsmoking, adult volunteers were fitted with two standard pulse-oximeter finger probes and two Rainbow probes for COHb detection. A radial arterial catheter was placed for blood sampling during three interventions:

(1) increasing hypoxemia in incremental steps with arterial oxygen saturations (SaO2) of 100% to 80%;

(2) normoxia with incremental increases in %COHb to 12%; and

(3) elevated COHb combined with hypoxemia with SaO2 of 100% to 80%.

Pulse-oximeter (SpCO) readings were compared with simultaneous arterial blood values at the various increments of hypoxemia and carboxyhemoglobinemia (≈25 samples per subject). Researchers reported the pulse CO-oximeter performance was analyzed by calculating the mean bias (SpCO – %COHb), standard deviation of the bias (precision), and the root-mean-square error (A(rms)).

The Masimo Rainbow SET(®) Radical-7 accurately detected hypoxemia with both normal and elevated levels of COHb.

Bias mean ± SD:

0.44% ± 1.69% at %COHb <4% -0.29% ± 1.64% at %COHb ≥4% P < 0.0001, and A(rms) 1.74% vs 1.67%). COHb was accurately detected during normoxia and moderate hypoxia

Bias mean ± SD:

-0.98 ± 2.6 at SaO2 ≥95%,

-0.7 ± 4.0 at SaO2 <95% P = 0.60, and A(rms) 2.8% vs 4.0%) When SaO2 decreased below approximately 85%, the Masimo Rainbow SET(®) Radical-7 pulse CO-oximeter always gave low signal quality errors and did not report SpCO values. Researchers concluded that in health volunteers, the Masimo Rainbow SET(®) Radical-7 pulse CO-oximeter accurately detects hypoxemia with both low and elevated COHb levels, and accurately detects COHb, but only reads SpCO when SaO2 is more than approximately 85%. See also …
Masimo Rainbow SET(®) Radical-7 pulse CO-oximeter About Page …

Feiner JR, Rollins MD, Sall JW, Eilers H, Au P, Bickler PE. Accuracy of carboxyhemoglobin detection by pulse CO-oximetry during hypoxemia. Anesth Analg. 2013 Oct;117(4):847-58.

Medical Monitors USA
Masimo Rainbow Radical-7 Monitor Color Screen 2,795 on Jan. 16, 2014
Masimo Radical-7 9500 Touchscreen Handheld Color Screen 2,795 on Jan. 16, 2014

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