Clinical Monitoring Flashcards
EEG recording produced by
Synchronous depolarization of cell bodies and dendrites as chemical activity is converted to electrical activity
EEG pattern for anesthesia (general and deep)
General: Theta, slower, higher amplitude
Deep: Delta, wider, loopy sleep waves
General anesthesia produces _____ changes on EEG
Dose-dependent
Most common patient perceptions of awareness under anesthesia (5)
- Sounds and conversation (89-100%)
- Sensation of paralysis (85%)
- Anxiety and panic
- Helplessness and powerlessness
- Pain (39%)
Least common patient perceptions of awareness under anesthesia (3)
- Visual perceptions
- Intubation
- Feeling operation without pain
BIS number ranges (normal, general anesthesia, values more likely to have recall)
- Range from 0-100
- General anesthesia: 40-60
- More likely to have recall: >70
Anesthetic technique effect on SSEPs, how to change your anesthetic when they’re used
- IV agents have less effect than inhaled agents
- Propofol/narcotic gtt, no paralysis
- 0.5-1 MAC inhaled agent if cannot do TIVA
Normal ICP in adults
5-15 mmHg, lower in infants/children
MAP calculation
SBP + 2xDBP / 3
Upper arm BP vs down arm
Upper arm=10mmHg lower than down arm
Calf/ankle BP vs arm
Calf/ankle approximately 5mmHg lower than arm
Normal PA pressure
15-30/4-12
Normal PA Wedge pressure
4-12
PA catheter should reside where?
West Zone III of lung
- Bulk of pulmonary blood flow
- Direct communication between right heart and pulmonary pressures and left intraventricular pressures
Mixed venous O2 saturation (SvO2) measures (and normal value)
- Percentage of SaO2 after tissue extraction
- Reflects overall tissue utilization of O2, tissue perfusion, CO
- Alteration in SaO2 will cause alteration in SvO2
- Normal value 5-77%
Oxyhemoglobin dissociation curve
Relationship between plasma O2 and Hgb saturation
-Reflects changing affinity of O2 to Hgb
Right shift of oxyhgb dissociation curve
Decreased affinity so O2 is released to the tissues
-Caused by hypercapnia, fever, acidosis, elevated 2,3DPG
Left shift of oxyhgb dissociation curve
Increased affinity of O2 to Hgb = higher saturation for given PaO2
-Caused by hypocapnia, hypothermia, alkalosis, decreased 2,3DPG
SpO2 50%=PaO2 ____
SpO2 60%
SpO2 90%
50% = PaO2 27 mmHg 60% = PaO2 30 mmHg 90% = PaO2 60 mmHg
End Tidal CO2 Monitoring
Estimates PaCO2 and evaluates ventilation and dead space
Possible causes for increasing baseline on ETCO2
- Defective exhalation valve
- Rebreathing of previously exhaled CO2
- Exhausted CO2 absorber
Possible causes for gradual increase in ETCO2
- Hypoventilation
- Increased metabolism (fever, pain, shivering)
- Partial airway obstruction
- Absorption of CO2 from exogenous source (Lap surg)
Possible causes of suddenly elevated ETCO2
- Tourniquet release
- Bicarb administration
- Reperfusion during vascular grafting
- Malignant hyperthermia
Possible causes for decreasing ETCO2
- Cardiopulmonary arrest
- Pulmonary embolism
- Sudden hypotension, massive blood loss
- Cardiopulmonary bypass
Possible cause of Low ETCO2 with good plateau
- Hyperventilation
- Hypothermia
- Dead space ventilation
Possible causes of low ETCO2 without plateau
- Partially kinked ETT
- Bronchospasm
- Mucous plugging
- Poor sampling techniques
Possible causes of sudden ETCO2 decrease to near 0
- Leak in system
- ETT in hypopharynx or cuff leak
- Poorly fitting anesthetic mask
- Partial disconnect from ventilator circuit
Possible causes of loss of ETCO2
- Airway disconnection
- Dislodged ETT, esophageal intubation
- Totally obstructed/kinked ETT
- Complete ventilator malfunction
- Air embolism
- Best place to hear breath and heart tones with precordial
- Best place to listen at induction/emergence
Apex of heart
- 5th left intercostal space at midclavicular line just below left nipple
- Induction/emergence: suprasternal notch, best for airway monitoring
