Common Intraop Problems Flashcards
Hypoxemia
PaO2
V/Q mismatch - hypoxemia
most common pathophysiologic cause of hypoxemia
results from decreased alveolar ventilation in respect to perfusion
ex) shunts, pneumonia, PE, pulmonary edema
Improper placement of tube - hypoxemia
endobronchial, esophageal, oropharyngeal
oxygen supply - hypoxemia
equipment failure or high altitude
alveolar hypoventilation - hypoxemia
COPD, asthma, bronchitis drug overdose neuromuscular abnormality (MG, Guillan Barre)
Intrapulmonary shunting - hypoxemia
- decreased ventilation in perfused lung regions -> shunting of venous blood without being oxygenated
- O2 therapy unable to improve PaO2
Diffusion Abnormality - hypoxemia
impaired transfer of O2
- sarcoidosis, ILD
decreased O2 carrying capacity
Bronchospasm
Causes:
- preexisting reactive airway disease
- manipulation of airway
- ETT with inadequate anesthesia
- ETT with bronchial stimulation
- histamine release, anaphylaxis, pulmonary edema
Investigations of bronchospasm
examine ETT, check positioning - look for wheezing - capnograph - high peak pressure RULE OUT: PTX, PE, pulmonary edema
Management of Bronchospasm
increase FiO2 increase anesthetic depth increase expiratory time and decrease RR give albuterol, epi for anaphylaxis hydrocortisonefor long term
Hypotension
MAP
Decreased preload - hypotension
low blood volume (hemorrhage, fluid loss)
decreased venous return -> position
Tamponade, PTX, compression by surgeon, excessive PEEP
Decreased afterload - hypotension
sepsis, vasodilating drugs (anesthetics)
anaphylaxis reaction, neuro injury
Decreased contractility - hypotension
MI, arrhythmias, CHF, anesthetic effect, electrolyte abnormalities
Hypertension
BP > 140/90 or MAP >20-25% from baseline - examine BP cuff, artline, IV - review events thus far - check for hypoxia and hypercarbia - check anesthetic level Tx: anti-hypertensives (beta-blockers, vasodilators)
Primary HTN
No known cause (70-95%)
Secondary HTN
- pain/surgical stimuli (inadequate anesthesia), ETT stimulation
- hypercarbia, hypoxia, hypervolemia, hyperthermia
- intracranial pathology
- endocrine problems
- alcohol withdrawal
- malignant hyperthermia
Timing of HTN
prior to induction -> withdrawal from medications
post-induction -> laryngoscopy, ETT stim, improper placement, pain
during case -> pain control, hypercarbia, pneumoperitoneum, fluid overload, bladder distention, drugs
Hypercarbia
increased CO2 levels (blood gas or ETCO2)
- examine pulse ox
- vent settings and CO2 absorber
- consider ABG
- assist breathing or increase minute ventilation
Increased CO2 production - hypercarbia
malignant hyperthermia
sepsis
fever/shivering
thyrotoxicosis
Decreased CO2 elimination - hypercarbia
reduced minute ventilation
increased dead space
drug effects
Timing of hypercarbia
Start of case -> ETT placement, vent settings, oversedation
Post-induction -> malignant hyperthermia, vent settings, thyrotoxicosis, CO2 absorber
During Emergence -> inadequate reversal, residual narcotics, hypoglycemia, electrolyte disturbances
Hypocarbia
decreased CO2 levels (ABG, ETCO2)
check circuit, check BP, HR, SpO2
check vent settings
Tx underlying cause
Causes - hypocarbia
Hyperventilation - decreased metabolic rate
PE, Air embolus, cardiac arrest, ETT problems
High peak airway pressures
circuit probelms, ETT problem, drug induced, decreased pulmonary compliance
Tx: check tubes, hand ventilate, FiO2 of 100%, auscultate, suction, consider paralysis
Oliguria
urine production
DDx for oliguria
Prerenal - intravascular fluid depletion
Renal - lack of perfusion, renal damage
Postrenal - obstruction
MI
damage to heart muscle from imbalance of myocardial O2 supply and demand
- atherosclerosis, aneurysm, artery spasm, aortic stenosis, blood viscosity, embolus
Investigations for MI
Lead II - most sensitive for arrhythmia Lead V5 - most sensitive for ischemia detection - together, detect 90% of events ST-depression -> subendocardial ST-elevation -> transmural T-wave inversion and Q-waves check TEE and cardiac enzymes
Tx for MI intraop
Goal: maintain acceptable balance of O2 supply and demand
- maintain BP and 100% FiO2
- confirm placement of leads
- notify surgeon
- consider reducing anesthetic, beta-blockers
- consider fluid therapy, anticoagulation, inotropic agents to support contractility
Bradycardia
heart rate anticholinergics
unstable -> FiO2 of 100%, abort anesthetic, CPR or pacing
Tx: underlying cause
DDx of Bradycardia
altered pulse formation (vagal tone) drugs (beta-blockers, Ca-blockers, cholinergics, narcotics) pathology (thyroid, sick sinus syndrome) MI surgical/anesthesia stimuli reflex bradycardia
Tachycardia
heart rate > 100 bpm ensure adequate oxygenation and ventilation verify ECG placements assess BP or artline volume status, depth of anesthesia Tx: underlying cause
Tachycardia and hypertension
pain/light anesthesia hypovolemia, hypercapnia, hypoxia Drugs Electrolyte abnormalities MI Endorcrine abnormalities Bladder distention
Tachycardia and hypotension
anemia, CHF, valvular heart disease
PTX, immune stuff
MI, sepsis, PE
Delayed Emergence
check for residual neuromuscular blockade check for hypoxia or hypercarbia check glucose/electrolytes consider narcotic reversal (naloxone) consider benzo reversal (flumazenil) check body temp and neuro status
DDx for delayed emergence
residual drug effects Neuro complications metabolic complications Respiratory failure CV collapse hypothermia sepsis
