It is an early indicator of airway or respiratory compromise

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Transcript It is an early indicator of airway or respiratory compromise

Monitoring The Emergency Patient
( Emergency Medicine Resident)
-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
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.
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)
-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)
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
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
-Interference with transfer through nail bed (ex: synthetic nail)
-Alterations in Hb (ex: severe anemia or abnormal Hb)
-Carboxyhemoglobin (COHb) gives falsely high reading
-Methhemoglobin (MetHb) gives a low saturation when it is high and vice
-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
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
-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
-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)
Number of patient days reDisadvantages:Reduction in rate of harm by
quired to reach 80% chance
the use
of capnography
of identifying
a reduction in
-Misleading CO2 readings
occur with ingestion
of carbonated
beverages(ex: Pepsi),antacids or with esophageal intubation after
1 per 1000 days
bag or mask ventilation 50% reduction
1 per
1000 days
20% reduction
is falsely elevated after
injection of sodium bicarbonate
ce of deaths or serious
associated with airway
1 per 1000 days
10% reduction
3 million
1 per 2000 days
20% reduction
1.4 million
raphy useful in the identification of correct placement of a tube in the trachea?
phy to be useful in reducing harm associated with airway incidents in Intensive Care, it should be able to
ct placement of a tube in the trachea and confirm incorrect placement of a tube in the oesophagus with an
exceeds clinical examination. The options for tube placement and capnographic confirmation are shown in
nography at intubation: Diagnostic possibilities
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
• 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 (<4 mm Hg CO2)
to tan (4-15mm Hg CO2) to yellow (>20 mm Hg CO2) DEPENDING ON CO2
- The indicator is inserted between the ETT and the ventilator bag
-Remember: YELLOW
(Correct intubation and tube is in the trachea)
Disadvantage:It is not sufficiently accurate to give quantitative measurements
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
-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
-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