1. Monitoring The Emergency Patient ABDULRAHMAN SINDI ( Emergency Medicine Resident)

2. PRESPECTIVE: -To Monitor means to measure or observe a physiologic parameter either continuously or intermittently -Monitoring devices provide a “snap shot in time” and a window into the clinical status of the patient, detecting deterioration,tracking improvement, or measuring the effectiveness of interventions. -Basic Monitoring modalities used in the practice of emergency medicine : Non invasive blood pressure monitoring Pulse Oximetry (oxygenation monitoring) End- Tidal Carbon Dioxide (ventilation monitoring) Fetal Monitoring Cerebral Function Monitoring

3. NONINVASIVE BLOOD PESSURE MEASUREMENT: There are 2 available devices for noninvasive BP monitoring :- 1-Cuff-type 2-Radial arterial noninvasive waveform analysis Advantages include:- -Time saving -Timed repetition of BP measurements -Continuous display of systolic,diastolic, pulse rate and mean BP 1-Cuff-type devices: -These devices use a detection system based on auscultatory, oscillometric or Doppler principles, in which the last 2 methods are the most accurate. -The mechanism: The cuff inflates deflates gradually while deflating it senses the pulse amplitude of oscillations (pulsations) transmitted my movement of the arterial wall under the cuff. An abrupt increase in oscillation signals an opening of the artery and increase in volume Systolic Pressure After that the oscillations increase to a peak then falls rapidly the point Where there is no longer alteration in the magnitude of oscillation Diastolic Pressure.

4. Disadvantages of cuff-type include difficulty to use in :- Obese patients Uncooperative moving patient Extremely high of low BP 2-Radial arterial non invasive wave form analysis (The Vasotrac): It is a newer method, that measures the radial artery BP and pulse rate every 12-15 beats and displays a radial pressure waveform. Advantages: accurate and comparable to invasive method. Disadvantages:- expensive and requires patient to remain still ( as the device requires 12-15 consecutive beats without movement to give the accurate measurement)

5. INVASIVE BLOOD PRESSURE MEASUREMENT: -This is the most accurate method of BP measurement -It is done through an intra arterial catheter which is transduced to an electronic display Disadvantages:- Although the risk of arterial injury or thrombosis is low, it is still present and can result in vascular compromise Indications to use invasive arterial catheter include:- 1-Extremely high (>250 mm Hg systolic) or low (<80 mm Hg systolic) BP 2-Patients requiring continous BP monitoring due to rapid fluctuations in BP (ex: rapid antihypertensive therapy with nitroprusside) 3-Impending shock states 4-Patients with anatomic abnormalities(ex: not suitable limb and morbidly obese patient) 5-Conditions where frequent arterial sampling is required

6. BLOOD GAS MONITORING: Devices used in blood gas monitoring include:- 1-Pulse oximetry 2-End –tidal carbon dioxide monitoring 1-Pulse Oximetry: -It measures arterial oxygen saturation(SpO2) -transmission oximetry is the most common type used -transmission oximetry is based on differences in optical transmission spectrum of oxygenated and deoxygenated Hb -It measures pulse variations in red and infrared light transmitted through a tissue bed Advantages:- -Safe -Easy to use -Reliable -Inexpensive Limitations of oximetry technology :- -Excessive movement -Poor perfusion and vasoconstriction (ex: shock and hypothermia) -Interference with transfer through nail bed (ex: synthetic nail) -Alterations in Hb (ex: severe anemia or abnormal Hb) 1-

7. -Carboxyhemoglobin (COHb) gives falsely high reading -Methhemoglobin (MetHb) gives a low saturation when it is high and vice versa -Higher incidence of error was detected with dark skinned people NOTE: Adequate oxygen saturation does not ensure adequate ventilation, particularly in patients with decreased level of consciousness ETco2 monitoring is required for assessment of ventilation 2-End-Tidal Carbon Dioxide Monitoring: The concentration of C02 in an exhaled breath is intrinsically linked to: tissue metabolism, systemic circulation, and ventilation Methods Used For Carbon Dioxide Monitoring:- Capnography -It is a graphic record represented asa a waveform, or capnogram of CO2 concentrations in respired gases during a respiratory cycle -It is also diagnostic for some disease as it gives characteristic wave forms -It is the earliest indicator of airway/respiratory compromise - ETco2 represents the maximum CO2 at the end of each tidal breath Advantages include:- -It provides continuous real-time breath-to-breath feed back on the clinical status of the patient

8. -The presence of normal capnogram indicates a patent airway and normal ETco2 levels indicate adequate ventilation -Along with visualizing tracheal rings on bronchoscopy,capnography is another gold standard to confirm intubation of the trachea -It is 100% sensitive and specific for confirmation of correct tube placement and it may be more sensitive than clinical assessment -It is an early indicator of airway or respiratory compromise -Helps assessing cardiac out put and effectiveness of CPR and is the earliest indicator of return of spontaneous circulation (ROSC) as it measures ETco2 -Helps Assessing response to treatment in patients with acute respiratory distress -Determine adequacy of ventilation in altered mental status patients -Assess ventilatory status in actively seizing patients -Helps to detect PE -Helps to detect metabolic acidosis, the more acidotic the lower HCO3 and the lower ETco2 and the higher the respiratory rate, so it can help differentiate DKA from non DKA patients ( in DKA patients there is metabolic acidosis, compensatory tachypnea and low ETco2)

9. Disadvantages:- -Misleading CO2 readings may occur with ingestion of carbonated beverages(ex: Pepsi),antacids or with esophageal intubation after bag or mask ventilation -ETco2 is falsely elevated after injection of sodium bicarbonate

11. Figure 3-1B : Shows prolongation of phase 2-3 that occurs with with obstructive lung disease. other causes are bronchospasm, kinked ETT or leaks in the breathing system Figure 3-1C: The slope of phase 3-4 can be increased by same previous obstructive factors and it could be a normal physiologic variation as in pregnancy Figure 3-1D: This slope can be prolonged and blend with expiratory phase in anatomic cuff leaks. Capnometry It is the quantitative measurement of ETco2 displayed as a number without a wave form

12. Colorimetric CO2 detectors -It uses color scales to estimate ranges of ETco2 -Its use is limited to confirmation of correct endotracheal intubation (ETT) placement and its continuous location in the trachea -Colorimetric CO2 detectors use PH-sensitive filter paper impregnated with metacresol purple which changes color from purple ( 20 mm Hg CO2) DEPENDING ON CO2 concentration - The indicator is inserted between the ETT and the ventilator bag -Remember: YELLOW YES (Correct intubation and tube is in the trachea) Disadvantage:- It is not sufficiently accurate to give quantitative measurements

13. Fetal Monitoring : -Obstetricians and gynecologists recommends fetal monitoring for 2-6 hours after abdominal trauma -Fetal monitoring is done in ED to detect fetal distress -Persistent fetal tachycardia, bradycardia, loss of baseline variability or decelerations following uterine contractions require urgent obstetric consultation -fetal monitoring is done by CTG and U/S -CTG is mostly unavailable in ED, so U/S is used to monitor fetal heart rate CEREBRAL FUNCTION MONITORING: -Bispectral index monitors (BIS) analyses and processes a patients EEG during sedation to produce a single number-the Bispectral index -This number ranging from 0 to 100 is used as an indicator for the depth of sedation, with 0 representing EEG silence and 100 a fully awake adult -The evidence of its reliability to reflect depth of sedation is conflicting -the threshold beyond which ventilatory compromise occurs has not been determined,further limiting the use of routine BIS monitoring for sedation in ED

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