NCE Flashcards
↑PVR
Hypoxia
Low FiO2 < 30%
Acidosis ↓pH ↑H+
Hypercarbia ↑CO2
PEEP ↑ITP or airway pressures
Mechanical ventilation
Light anesthesia/pain
Surgical stress SNS stimulation
Vasoconstrictors
HPV response to atelectasis
Trendelenburg
Nitrous oxide N2O
Desflurane & Ketamine
Hypothermia
↓PVR
Hyperoxia ↑PaO2
↑FiO2 100%
Alkalosis ↑pH ↓H+
Hypocarbia ↓CO2
Hyperventilation
No PEEP ↓ITP
Low airway pressures
Spontaneous ventilation
Deep anesthesia
Vasodilators iNO, NTG, PDEi, PGE1, PGI2, CCBs, ACEi
Pulmonary Vascular Resistance
PVR = [(Mean PAP - PAOP) / CO] x 80
Normal 150-250 dynes/sec/cm
Acidosis
↑CBF ↑ICP
↑P50 (R shift)
↑SNS tone ↑dysrhythmias risk ↓contractility
↑PVR
Hyperkalemia
Anion Gap
= Na+ - (Cl¯ - HCO3¯)
Normal 8-12 mEq/L
When to calculate the anion gap?
Metabolic acidosis
Metabolic Acidosis
Normal AG Causes
HARDUP
Loss HCO3¯ or ECF dilution
NS hyperchloremia
Hypoaldosteronism
Acetazolamide
Renal tubular necrosis
Diarrhea
Uretosigmoid fistula
Pancreatic fistula
Metabolic Acidosis
Elevated AG Causes
MUDPILES
> 12 mEq/L
Methanol
Uremia
Diabetic ketoacidosis
Paraldehyde
Isoniazid
Lactate ↓DO2, sepsis, cyanide poisoning
Ethanol or ethylene glycol
Salicylates inhibit the Krebs cycle
Alkalosis
↓CBF ↓ICP
↓P50 (L shift)
↓coronary blood flow
↑dysrhythmias risk
↓PVR
Hypokalemia
↑ionized Ca2+
Metabolic Alkalosis
Causes
Loops diuretics
Vomiting
Antacids
Hyperaldosteronism
Oxyhemoglobin Curve
Left Shift
Alkalosis ↑pH ↓H+
Hypocarbia ↓CO2
↓2,3 DPG
Hypothermia
Fetal/Met/CO Hgb
Lungs
HaLdane
Oxyhemoglobin Curve
Right Shift
Acidosis ↓pH ↑H+
Hypocarbia ↑CO2
↑2,3 DPG
Hyperthermia
Tissues
Bohr O2 offloading
PAO2
Alveolar O2 partial pressure
= FiO2 x (760 - 47 mmHg) - [PaCO2 / RQ]
CO2 Production
200 mL/min
O2 Consumption
250 mL/min
OR
3.5 mL/kg/min
How does body temperature affect O2 consumption?
Direct correlation
↓core body temperature ↓O2 consumption
Every 1°C ↓5-7%
Acute Hypercarbia
↑CO2 10 mmHg > 40 ↓pH 0.08
Chronic Hypercarbia
↑CO2 10 mmHg > 40 ↓pH 0.03
Hypoxia Causes:
- Hypoxic mixture
- Hypoventilation
- Diffusion limitation
- V/Q mismatch
- Shunt
↓FiO2
Normal A-a gradient
+FiO2
Hypoxemic mixture
O2 pipeline failure
High altitude
Hypoventilation
Normal A-a gradient
+FiO2
Opioid overdose
Residual anesthetic agent or NMB
Neuromuscular disease
Obesity hypoventilation
V/Q Mismatch
Most common hypoxemia cause***
↑A-a gradient
+FiO2
COPD
OLV
Impaired HPV
Embolism - air, gas, amniotic fluid
Diffusion Impairment
↑A-a gradient
+ FiO2
Pulmonary fibrosis
Emphysema
Intestitial lung disease
Shunt
↑A-a gradient
FiO2 does NOT help
Atelectasis
Pneumonia
Bronchial intubation
Intercardiac shunt
Anatomic shunt
What inhibits HPV?
Volatiles MAC > 1.5
Hypoxia
Alkalosis ↑pH ↓H+ ↓CO2
Hypocarbia/hyperventilation
Vasodilators - PDEi or SNP
Vasoconstrictors
Excessive PEEP ↑VT
Hypervolemia LAP > 25
Hemodilution
Hypothermia
SpO2:PaO2
SpO2 80 : PaO2 50 mmHg
70 : 40
60 : 30
Soda Lime Reaction
CO2 + H2O → H2CO3 (carbonic acid)
H2CO3 + 2NaOH (sodium hydroxide) → Na2CO3 (sodium carbonate) + H2O + heat
Na2CO3 + Ca(OH)2 → CaCO3 (calcium carbonate) + 2NaOH
Soda Limb
Absorption Capacity
26L CO2 per 100g absorbent
How does soda lime neutralize CO2?
NaOH = weak base
CO2 = acid
KOH
Potassium hydroxide
Dessication → CO & compound A
Amsorb
Ca(OH)2
No CO
NO compound A
Expensive $$$
Low absorptive capacity
Only able to absorb 10.6L CO2 per 100g
Baralyme
Removed from the market
Sevo + baralyme → increased breathing circuit fire risk
Dead Space
Vd 2 mL/kg or 150 mL
1 Atmosphere
Patm
760 mmHg
760 Torr
1 bar
100 kPa
1,033 cmH2O
A - a Gradient
PAO2 - PaO2
Normal < 15 mmHg
What ↑A-a Gradient?
Shunt
V/Q mismatch
Diffusion defect
Aging
Vasodilators
R → L shunt
Trachea
Begins at C5
Ends at T4-5
Carina
T4-5
Angle of Louis
Pneumocytes
Type 1 provide gas exchange surface
Type 2 produce surfactant & type 1
Tracheobronchial Functional Airway Divisions
Conducting zone = trachea, bronchi, & bronchioles 0-4
Transitional zone = respiratory bronchioles 17
Respiratory zone = alveolar ducts & alveolar sacs 20-23
Reynolds Number
Re = (Density x Velocity x Diameter) / Viscosity
Laminar flow [viscosity] < 2,000
Transitional 2,000-4,000
Turbulent [density] > 4,000
Dynamic Compliance
Cdyn = VT / (PIP - PEEP)
Static Compliance
Cstat = VT / (Pplat - PEEP)
Normal 35-100 mL/cmH2O
↑PIP + Normal Pplat
↑resistance OR ↑inspiratory flow rate
Kinked ETT
Endotracheal tube cuff herniation
Bronchospasm Bronchial secretions
Airway compression
Foreign body aspiration
↑PIP & ↑Pplat
↓total lung compliance OR ↑VT
Endobronchial intubation
Pulmonary edema
Pleural effusion
Tension pneumo
Atelectasis
Chest wall edema
Abdominal insufflation
Ascites
Tburg
Inadequate muscle relaxation
Volatile Anesthetics MOA
Unconsciousness
Cerebral cortex
Thalamus
RAS
Volatile Anesthetics MOA
Amnesia
Amygdala
Hippocampus
Volatile Anesthetics MOA
Autonomic Effects
Pons
Medulla
Volatile Anesthetics MOA
Analgesia
Spinothalamic tract
Volatile Anesthetics MOA
Immobility
Spinal cord ventral horn
Where the upper & lower motor neurons synapse
Mapleson A
Spontaneous ventilation
> FGF 0 = APL <
Mapleson D
Controlled ventilation
0 APL = FGF <
Mapleson E
Ayre T-piece
No reservoir bag or APL
= FGF <
Mapleson F
Jackson-Rees
No APL
0 = FGF <
Opioid MOA
Pre-synaptic ↓Ca2+ release
Post-synaptic ↑K+ hyperpolarizes the cell membrane ↓RMP
Mu 1
Supraspinal & spinal analgesia
Bradycardia
Euphoria
Low abuse potential
Miosis
Hypothermia
Urinary retention
Mu 2
Spinal analgesia
Bradycardia
Respiratory depression
Constipation
Physical dependence
Delta
Enkephalins
Supraspinal & spinal analgesia
Respiratory depression, physical dependence, urinary retention, & pruritis
Kappa
Dynorphins
Supraspinal & spinal analgesia
Miosis, diuresis, & hypoventilation
Agonist-antagonist MOA
Anti-shivering
Sedation, dysphoria, delirium, & hallucinations
AGM O2
- O2 pressure failure alarm
- O2 pressure failure device (failsafe)
- O2 flowmeter
- O2 flush valve
- Ventilator drive gas
EKG Normal Axis
-30° → +90°
Lead I +
aVF +
Poiseuille
= (π∙r^4∙∆P) / 8ηl
Stenosis
Anesthesia Management
Full, slow, & constricted
Maintain or ↑afterload
Aortic Stenosis
Normal aortic valve orifice 2.5-3.5 cm^2
SEVERE < 0.8 cm^2
Mitral Stenosis
Normal mitral valve orifice 4-6 cm^2
SEVERE < 1 cm^2
Insufficiency/Regurgitation
Anesthesia Management
Full, fast, & forward
AVOID bradycardia
Pulsus Parvus
Aortic stenosis → narrow PP & small amplitude
Pulsus Tradus
Aortic stenosis → slower systolic upstroke & delayed peak
Bisferiens Pulse
Aortic regurgitation → biphasic systolic peaks
Sharp upstroke & low DBP
Wide pulse pressure
Pulsus Alternans
Severe LV failure
Alternate ↑↓A-line waveform
Pulsus Paradoxus
Cardiac tamponade ↓SBP > 10 mmHg w/ inspiration
Thoracoaortic Aneurysm Classifications
Crawford
Most common classification system*
Crawford Type
- All or most descending thoracic aorta + only upper abdominal aorta
- All or most descending + most abdominal
- Only lower descending + most abdominal
- No descending + most abdominal
Aortic Dissection Classification
Stanford & DeBakey
Stanford
Type A - Ascending
Type B - Does not involve the ascending aorta
DeBakey
- Tear in ascending aorta + dissection along entire aorta B
- Tear in ascending aorta + dissection only in ascending aorta A
- Tear in proximal descending aorta D
a. Dissection limited to thoracic aorta
b. Dissection along thoracic & abdominal aorta
Antiarrhythmics 1a
Na+ channel blockers (phase 0)
Disopyramide
Norpace
Quinidine
Procainamide
Antiarrhythmics 1b
Na+ channel blockers (phase 0)
Lidocaine
Phenytoin
Mexiletine
Antiarrhythmics 1c
Na+ channel blockers (phase 0)
Flecainide
Propafenone
Moricizine
Antiarrhythmics 2
β blockers -olol
SA node phase 4
Antiarrhythmics 3
K+ ion channel blockers (phase 3)
Amiodarone
Sotalol
Ibutilide
DofetilideA
Antiarrhythmics 4
Ca2+ channel blockers (phase 2)
Verapamil
Nifedipine
Diltiazem
Nicardipine
Antiarrhythmics 5
OTHER
Adenosine
Atropine
Magnesium
Digoxin
Microshock
20-100 μA → V fib
MACROshock
1 mA = perception threshold
5 = max harmless current
10-20 = “let go” current
50 = pain or possible mechanical injury
100-300 mA → V fib
Line Isolation Monitor
Alarms when > 5 mA detected
1st fault
OR grounded
What is the maximum current leakage allowed in the OR?
10 μA