Monitoring in anesthesia Flashcards
what is monitoring
To watch & check a situation carefully for a period of time
what are the standards for basic anesthetic monitoring (2)
- standard I
- standard II
why do we monitor
Maintain normal patient physiology and homeostasis throughout the period of anesthesia
what does standard I state
it states that an anesthesia provider will be present with the patient throughout the anesthetic
what does standard II state
that the patients oxygenation, ventilation, circulation and temperature will be continually monitored
what is monitored during oxygenation (2)
- inspired oxygen
- blood oxygenation
how is oxygenation measured (2)
- hemoglobin saturation with a pulse oximeter
- observation of the skin
what is monitored during ventilation (2)
- qualitative clinical skills
- chest excursion
- auscultation of breath sounds (using a precordial or esophageal stethoscope)
- movement of the reservoir bag.
- Patients who are breathing spontaneously should be observed for signs of airway obstruction, including a tracheal tug, paradoxical chest movement, snoring, or upper airway sounds. - quantitative monitoring
- capnography ( CO2 concentration in exhaled breath)
how should mechanical ventilation be monitored
with an audible disconnet monitor
during ventilation how should tracheal intubation be verified (2)
- clinically
- by detection of exhaled CO2 (capnography)
how do you monitor circulation (3)
- ECG
- blood pressure measurement at least every 5 minutes
- continuous monitoring of peripheral circulation by:
- palpation
- auscultation
- plethysmography ( tool which measures changes in volume within an organ)
- arterial pressure
how do you monitor temperature
thermometry
what factors can interfere with the pulse oximeter (4)
- Shivering
– movement may make it difficult for the probe to pick up a signal. - Pulse volume
– the oximeter only detects pulsatile flow. When the blood pressure is low due to hypovolemic shock or the cardiac output is low or the patient has an arrhythmia, the pulse may be very weak and the oximeter may not be able to detect a signal. - Vasoconstriction
- it reduces blood flow to the peripheries. The oximeter may fail to detect a signal if the patient is very cold and peripherally vasoconstricted. - Carbon monoxide poisoning
- gives a falsely high saturation reading. Carbon monoxide binds very well to haemoglobin and displaces oxygen to form a bright red compound called carboxyhaemoglobin. This is misinterpreted by the oximeter as oxyhaemoglobin and the oximeter may read 100%, even though the true oxygen saturation is very low and the patient may be very hypoxic. This is only an issue in patients following smoke inhalation from a fire
A sudden increase in carbon dioxide production on a capnogram is the first warning sign for
malignant hyperthermia
A sudden drop in expired carbon dioxide on a capnogram is the first sign of what (2)
- pulmonary artery embolism
- air embolism
what does a capnograph do (4)
- can diagnose obstruction of the natural or artificial airways
- measures the expired CO2 conc
- helps determine whether tracheal or esophageal intubation was performed (if its normal looking )
- a sudden rise/ drop in expired CO2 can provide warning signs for certain conditions
what changes in CO2 elimination cause an increase in ETCO2 (4)
- hypoventilation
- rebreathing
- partial airway obstruction
- laparoscopy
what changes in CO2 production cause increase in ETCO2 (3)
- fever
- thyroid storm
- malignant hyperthermia
what changes in CO2 elimination cause a decrease in ETCO2 (3)
- hyperventilation
- hypoperfusion
- pulmonary embolism
what changes in CO2 production cause a decrease in ETCO2
hypothermia
what are the quantitative methods for assessing circulation (2)
- measurement of BP
- ECG
- rate
- rhythm
- ischemic changes
what are qualitative clinical signs of assessing circulation (3)
Assessment of:
- skin color and temperature
- the quality of a palpable pulse
- heart tones via an esophageal or precordial stethoscope
what should the correct BP cuff size be (2)
- width of the cuff should be 1.5 times limb diameter
- should occupy at least 2/3 of the arm.
what are 2 cuff sizes for adults :
- blue for most adult individuals (60-90Kg)
- red for morbid obese
why is selection of appropriate cuff size important
because a tight cuff leads to false high readings, while a Loose cuff gives false Low readings. (5)
what can cause BP reading errors (5)
- Pressure line is disconnected.
- Leakage from damaged cuff.
- Line is compressed (under someone’s foot or under a weal).
- Line contains water from washing!
- Monitor error: cuff cannot inflate due to infant or neonate limits.
during circulation what is more superior to the monitor
your clinal judgement
what must you check during circulation from time to time
check peripheral pulse volume every 10 minutes
- Radial A
- Dorsalis Pedis A
- Superficial Temporal A
palpation of the radial A indicates what
systolic BP> 90 mmHg
Palpation of Dorsalis Pedis A indicates what
systolic BP >80mmHG
Palpation of Superficial Temporal A indicates what
systolic BP > 80mmHg
how do you monitor invasive arterial blood pressure
arterial cannula
what is invasive ABP monitoring indicated in (5)
- major surgeries
- during deliberate hypotensive anesthesia
- during the use of inotropes
- cardiac surgery involving extreme hemodynamic changes/instability eg. pheochromocytoma
- repeated ABG sampling.
what information does the ECG provide (3)
(1) heart rate,
(2) cardiac rhythm
(3) information about possible myocardial ischemia (via ST segment analysis
what is the most common ECG used during anesthesia
5 electrode lead system
how do you clinically monitor temperature
with you hands
what tools can you use to monitor temperature (2)
nasopharyngeal and esophageal temperature probe
who should you especially avoid hypothermia in
pediatrics and geriatrics ( extremes of age)
why should you avoid hypothermia (6)
- Cardiac arrhythmias: VT & cardiac arrest.
- Myocardial depression.
- Delayed recovery (delays drug metabolism).
- Delayed enzymatic drug metabolism.
- Metabolic acidosis (tissue hypoperfusion → anerobic glycolysis → lactic acidosis) & hyperkalemia.
- Coagulopathy.
what are other ways of monitoring that can be done during anesthesia (6)
- Movement, facial expressions
- Nerve stimulators
- Gas monitoring
- Blood loss
- Urine output
- Cns awareness
what rules should you never forget during monitoring (5)
- Never start induction with a missing monitor: ECG, BP, SpO2.
- Never remove any monitors before extubation & recovery.
- NEVER ignore an alarm by the ventilator.
- ALWAYS remember that your clinical sense & judgement is better than & superior to any monitor.
- ALWAYS remember that there is NO such thing as “all monitors disconnected” → check that your pt is ALIVE!! Immediately check peripheral & carotid pulsations to make sure that your pt is not ARRESTED!! Once u have ensured pt safety reattach your monitors once again.
in summary how do you monitor the patient in OR (4)
The 4 basic monitors displayed on the screen:
1. ECG.
2. BP.
3. SpO2.
4. ± Capnogram (EtCO2).
what is the best monitor overall
a vigilant anesthetist
