Carbon Monoxide and the Rad-57 Jeremy T. Cushman, MD, MS, EMT-P Monroe County EMS Medical Director Division of Prehospital Medicine, URMC CO-Related Deaths in 2000 What is it? Carbon Monoxide (CO) is a colorless and odorless gas. It is poisonous to people and animals, because it displaces oxygen in the blood. It is produced by the incomplete burning of solid, liquid, and gaseous fuels. Appliances fueled with natural gas, liquefied petroleum (LP gas), oil, kerosene, coal, or wood may produce CO. Burning charcoal and running combustion engines (cars, motorcycles, generators, etc) produce CO. How much causes symptoms? Normal Hemoglobin • Normal oxygenation of the tetrameric (ie. 4 subunits) hemoglobin molecule. • As it goes from (deoxy)hemoglobin to oxyhemoglobin the color changes from blue, as in venous blood, then to pink, as in arterial blood. Carboxyhemoglobin • Here carbon monoxide (CO) enters the picture, and through its very high affinity for hemoglobin, displaces the oxygen from the hemoglobin. • This prevents oxygen being carried to the tissues and organs of the body. • Carboxyhemoglobin is reddish in color. Normal Physiology • Oxygen is carried from the lungs by the blood hemoglobin to the tissues, here the beating heart is shown, and normal healthy oxidative metabolism goes on. CO Poisoning • During Carbon Monoxide poisoning, CO is carried from the lungs by the blood hemoglobin to the tissues, preventing oxygen from being carried, and blocking normal oxidative metabolism. Symptoms of CO Poisoning SpCO Level Clinical Manifestations >5% Mild headache 10% Mild headache, shortness of breath with exertion 10-20% Moderate headache, shortness of breath 20-30% Worsening headache, nausea, dizziness, fatigue Severe headache, vomiting, vertigo, altered 30-40% judgment 40-50% Confusion, syncope, tachycardia 50-60% Seizures, shock, apnea, coma Caveat… Symptoms DO NOT always correlate with the SpCO level If symptomatic, and exposed to CO, the patient should be transported to the hospital for definitive determination REGARDLESS of the CO level read by the Rad-57 The Rad-57 Noninvasive measurement of both SpO2 (pulse oximetry) and SpCO (pulse CO- oximetry) DOES NOT REPLACE A GOOD ASSESSMENT Indications Two settings for its use: Screening patients for suspected exposure Screening emergency services personnel during rehabilitation We’ll first concentrate on the use of the device, then the specific protocol for each setting. Using the Rad-57 1. Connect the sensor cable to the Patient Cable Connector of the oximeter. Make sure the connection is secure and the cable is not twisted, sliced, or frayed. 2. Remove any substances (nail polish, paint, etc) on the patient’s second, third, or fourth digit that may interfere with the transmission of light between the sensor’s light source and photo detector. Sensor Placement 3. Attach the sensor to the patient, applying it to the index (second), middle (third), or ring (fourth) digits. Only these digits can be accurately used by the CO-Oximiter. SENSOR PLACEMENT IS VERY IMPORTANT When possible, use ring (fourth) finger, non- dominant hand. Insert finger until the tip of finger hits the STOP Block. Sensor should not rotate or shift freely on finger. LED’s (red light) should pass through mid- nail, not cuticle. There is a top and bottom, cable should be on top (nail side). Turning the device on 4. Press the Power button ON. POWER Press to turn ON. Press and HOLD to turn OFF. BATTERY INDICATOR 4 Green LED’s. Each represents 25% battery life. Use only Alkaline batteries. Self-Test 4. The machine will go through a self-test procedure: POWER ON: SENSOR ON FINGER All LED’s light up. Calibration mode begins Spinning zeroes 0 - 0 – 0. Completed in 20 second (avg.) DO NOT move sensor during calibration. Acquires reading and displays. DISPLAY Defaults to pulse rate and oxygen saturation reading. “PI” bar graph displays strength of arterial perfusion. Initial Display Oxygen Saturation on top in Red Pulse Rate on bottom in Green Green PI scale, indicates strength of arterial pulse Low SIQ LED indicates poor signal quality Press SpCO to display % carboxyhemoglobin Press “Bell” to silence alarms Measuring SpCO PRESS ORANGE SPCO BUTTON Display will toggle to CO mode for 10 seconds Carboxyhemoglobin reading in % on top “CO” displayed on bottom confirming mode ALWAYS confirm high readings by taking several measurements on DIFFERENT fingers and average Real-time SpCO indicator continuously reads SpCO Green: 1-9% Orange: 10-19% Red: 20% and above Important Notes! The device is not approved for use in patients weighing less than 30 kg (66 lbs) When examining multiple patients, turn the device OFF then ON to recalibrate between patients. Failure to do so could give you incorrect readings!!! Alarms Alarm indicator When violated, audible alarm will sound, parameter will flash Preset at factory: Sa02 (oxygen saturation) Low: 90% High: none Pulse Rate Low: 50 High: 140 SpCO (carboxyhemoglobin) Low: none Alarm silence High: 10% To adjust alarms: Press “Mode/Enter” twice Press “Next” key to scroll through parameters Use up and down keys to adjust Reverts to Factory settings after turned off. Care and Cleaning Once monitoring is complete, remove the sensor from the patient and turn the device off. Wipe the sensor and device with a soft cloth dampened with mild soap and water. Never submerge the sensor or the monitoring device. The Low SIQ Indicator… If the device indicates a “Low SIQ,” this refers to a low signal IQ and flashes when the SpO2 and SpCO measurements may be compromised. If this occurs: Reassess the patient. Check the sensor to ensure it is properly applied to the patient and inserted into the Rad-57 device. Determine if an extreme change in the patient’s physiology and blood flow at the monitoring site has occurred (e.g. an inflated blood pressure cuff, tourniquet, severe hypotension, hypothermia, or cardiac arrest). After completing this check, if the “Low SIQ” indication occurs frequently or continuously, you cannot rely on the device for either SpO2 or SpCO levels. The Perfusion Index… The Perfusion Index (PI) is a relative assessment of perfusion at the monitoring site. PI is displayed on a 10 segment LED bar on the right of the display ranging from <0.1% (very weak perfusion) to >5% (strong perfusion). The PI is shown as a “bouncing bar” indicator, where the peak of the bar coincides with the peak of an arterial pulsation. The highest LED will remain lit continuously to allow a PI level to be viewed. If evidence of low perfusion (<1%) is frequently displayed, find a better perfusion monitoring site and be sure the sensor is placed properly and there are no substances on the finger that could impede the emitter and photodetector. Very high ambient light situations can also produce falsely low PI. Should a low PI be persistent after these measures, review the procedure for “Low SIQ”. If a low PI still persists you cannot rely on the device for either SpO2 or SpCO levels. Cyanide and Methemeglobinemia Cyanide toxicity and methemoglobinemia cannot be readily determined by this device. The CO-Oximeter should be used in addition to clinical judgment and a normal reading in the setting of a patient with severe respiratory distress or cyanosis should not rule out a significant oxygen-transfer deficit (cyanide, met- hemoglobinemia, sulfhemoglobinemia, or profound anemia) requiring aggressive airway management and high-flow oxygen. Always treat the patient first and not the reading on the CO- Oximeter. Special note for Fire Personnel Unlike your gas meters, the RAD-57 is not intrinsically safe and should not be used in the presence of flammable substances! What to do with the numbers… The CO-Oximeter may be used on any patient greater than 30 kg where there is a concern for carbon monoxide exposure. For the non-rehabilitation scene, the following protocol applies Using Pulse CO-Oximetry The SpCO reading is to be used as a screening measure. Definitive carboxyhemoglobin determinations are performed via blood draw in the hospital setting. Any patient with suspected carbon monoxide poisoning should receive oxygen by a non-rebreather mask until their CO level can be determined. Any patient with airway compromise, respiratory distress, or symptoms of significant carbon monoxide poisoning (nausea, vomiting, loss of judgment, chest pain, dizziness, muscle weakness, or a change in mental status) should be treated according to the MLREMS Standards of Care and transported with high-flow oxygen to an emergency department regardless of the SpCO reading. Important Note! Pregnant women are at high risk in carbon monoxide exposure. The fetus is highly susceptible and the SpCO may be 10-15% higher than maternal readings. All pregnant women with possible CO exposure should be transported to the emergency department for evaluation. Who goes to the hospital? Any patient with a SpCO reading >12%, even if without symptoms, should be transported with high-flow oxygen to an emergency department. Any patient with a SpCO reading >25%, even if without symptoms, MUST be transported with high-flow oxygen to an emergency department. Who can appropriately not be transported? Patients with carbon monoxide exposure and SpCO <25% may be treated and released provided the following conditions are met: The patient is asymptomatic. The patient exhibits no signs of respiratory distress, and pulse oximeter reading is above 92%. The SpCO must be below 5% in non-smokers, and 10% in smokers. The lungs are clear on auscultation. There are no other significant burn or traumatic injuries. Both the pulse oximetry and the CO levels must be documented. The patient has medical decision making capacity per the MLREMS Refusal of Care Policy. Documentation Use of the Rad-57 and serially recorded SpCO levels should be documented accordingly in the Prehospital Care report. It cannot be emphasized enough that the patient’s clinical presentation is what should drive routine medical care and not the SpCO level observed. If there is ever doubt regarding the patient’s disposition, provide high flow oxygen and transport to the hospital for evaluation. Use in the Rehabilitation Sector When available, the use of pulse CO- oximetry is a valuable adjunct to assessment during rehabilitation. The use of hand-held pulse co-oximetry devices is optional, and not required for Incident Rehabilitation. Use in the Rehabilitation Sector The SpCO reading is to be used as a screening measure. Definitive carboxyhemoglobin determinations are performed via blood draw in the hospital setting. Any patient with complaints of chest pain, shortness of breath, or altered mental status should receive oxygen by a non-rebreather mask and moved to the Treatment Area, regardless of SpCO reading. Use in the Rehabilitation Sector If SpCO <5% and vital signs are within normal limits, the provider is encouraged to drink at least 16 ounces of fluid and may return to manpower/staging after a minimum of 10 minutes rest. If SpCO ≥5% and <12%, the responder may breathe ambient air and may not leave the rehabilitation area until their CO level is below 5%. If SpCO ≥12% the responder should be moved to the Treatment Area and receive high-flow oxygen until the SpCO is <5%. If SpCO ≥25%, the responder will be moved to the Treatment Area and transported with high-flow oxygen to an emergency department. Documentation Documentation of SpCO levels can be made on the rehabilitation log. Responders moved to the treatment area should have values recorded on the prehospital care report. Hyperbarics? The Monroe-Livingston Region does not have the services of a hyperbaric chamber, often used for treating life-threatening CO poisoning. All unstable patients with suspected CO poisoning should be transported to the nearest appropriate local facility for stabilization and serum carboxyhemoglobin determination. Conclusions The Rad-57 is an important device to be used in the evaluation of patients with suspected CO poisoning. Proper use of the device is imperative to assure adequate readings. Readings provided by the device should NEVER override clinical assessment – treat the patient, not the CO-oximeter!
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