Board Prep Flashcards
Decreased ETCO2
Hypothermia Hypothyroidism Increased Dead Space (COPD) Hyperventilation Decreased Cardiac Output Decreased CO2 production Circuit leak or Occlusion Pulmonary Embolism (air, thrombus, gas, fat, marrow, amniotic) Increased muscle relaxation Increased depth of anesthesia Surgical manipulation of the heart or thoracic vessels Wedging of the PA Catheter
Increased ETCO2
Increased CO2 production (MH, thyrotoxicosis, hyperthyroidism) Hyperthermia Shivering or convulsions Sepsis Rebreathing (valve prolapse, failed CO2 absorber) Hypoventilation Depression of the respiratory center Reduction of ventilation Increased or improving Cardiac Output Right to left intracardiac shunt Excessive catecholamine production Administration of blood or bicarbonate Release of aortic clamp/arterial clamp or tourniquet Glucose in the IV fluid Parenteral hyperalimentation CO2 insufflation Subcutaneous epinephrine injection
Minimal to zero ETCO2 or Sudden Drop
Equipment Malfunction ETT disconnect, obstruction, or total occlusion Bronchospasm No Cardiac Output Cardiac Arrest Bilateral PTX Massive PE Esophageal intubation Application of PEEP Cricoid pressure occluding tip of ETT Sudden, severe hypotension
Determining source of decreased ETCO2
Call for help
Assess vital signs
Feel for a pulse
Take patient off ventilator and handbag listening for breath sounds
EKG interpretation
Rhythm Regularity P wave (2.5 mm long and high) (Best viewed in Lead II) PR interval (No longer than 0.2 seconds) Q wave QRS complex (up to 0.12 seconds) (R & R prime in V1 = RBBB, R & R prime in V6 = LBBB) ST segment (V5 most sensitive lead) T wave Axis
ASA recommendations for preoperative EKG
Age >50 yo (good for one year if 50-69, good for 6 months if >69)
History of cardiovascular disease or HTN (mandatory if changes in symptoms)
History of DM (required if >40 yo or has had DM >10 years)
Central nervous system disease
Standard ASA Monitors
Oxygenation (pulse ox)
Ventilation (ETCO2, respiratory volumes, disconnect alarms)
Circulation (EKG, blood pressure, HR - every 5 minutes)
Temperature
Indications for arterial line
Continuous real time blood pressure monitoring
Planned pharmacological or mechanical cardiovascular manipulation
Repeated blood sampling (ABG, Hgb, Glucose)
Failure of indirect BP measurement
Supplementary diagnostic information from the arterial waveform (PPV)
Patient with end organ disease
Patient with large fluid shifts
Arterial line complications
Distal ischemia (thrombosis, proximal emboli) Pseudoaneurysm AV fistula Hemorrhage Hematoma Infection Skin necrosis Peripheral neuropathy Misinterpretation of data Cerebral air embolism from retrograde flow from flushing
Indications for central line
CVP monitoring Transvenous cardiac pacing Pulmonary Artery Catheter Temporary hemodialysis Drug administration (vasoactive, hyperalimentation, chemotherapy, prolonged antibx) Rapid infusion of fluids Major surgery with large fluid shifts Aspiration of a venous air embolus Inadequate peripheral access Sampling site for repeated blood testing
PA Catheter measurements
Cardiac Output and Index (CO/CI) Pulmonary Artery Pressure (PAP) Central Venous Pressure (CVP) Calculation of oxygen delivery Assessment of cardiac work Mixed Venous Oxygen Saturation (MVO2) Pulmonary Capillary Wedge Pressure (PCWP) Systemic Vascular Resistance (SVR)
Indications for PA Catheter
Cardiac (CHF, low EF, left sided valvular dz, CABG, aortic cross clamp)
Pulmonary (COPD, ARDS)
Complex fluid management (shock, burns, acute renal failure)
High risk obstetrical care (eclampsia, placental abruption)
Neurological (sitting craniotomy, venous air embolus)
Causes of Hypernatremia
Inadequate intake of fluid
Renal loss of hypotonic fluid (diuretics, DI, intrinsic renal disease)
Extrarenal (nonrenal loss of H20)
Primary Na gain (hypertonic tube feeds or fluids)
Clinical features of Hypernatremia
Altered mental status Lethargy Confusion Coma Seizures Pleural effusion Ascites Peripheral edema Heart Failure Thirst Nausea and Vomiting Neuromuscular irritability
Treatment of Hypernatremia
Determine volume status (diuresis if hypervolemic) (Free H2O deficit = {(plasma Na/140)-1} x kg x 0.6, replace half of water deficit in first 24 hours, then remainder over 2-3 days, use 5% dextrose in water or 0.45% NaCl)
Rate of Na correction should not exceed 0.5 mEq/L per hour
Treatment of Central Diabetes Insipidus
DDAVP (IV 2-4 mcg)(Nasal Spray 10-40 mcg)
Low Na Diet
Low dose thiazide diuretic
Carbamazepine (enhances vasopressin secretion)
NSAIDs
Treatment of Nephrogenic Diabetes Insipidus
Treat underlying cause
Treat symptomatic polyuria (Low Na diet, thiazide diuretic)
Causes of hypovolemic hyponatremia
Non renal (GI losses, integumentary losses, third spacing, cerebral salt wasting)
Renal (Diuretics, osmotic diuresis, hypoaldosteronism, salt wasting nephropathy, post obstructive diuresis, non-oliguric acute tubular necrosis, acute and chronic renal failure)
Causes of euvolemic hyponatremia
Polydipsia (psychogenic, exercise induced, medications)
Administration of hypotonic IV fluids
Beer potomania
SIADH (neurologic, pulmonary disease, malignant tumors, major surgery, pharmacologic)
Causes of hypervolemic hyponatremia
Renal (acute or chronic failure) Non renal (heart failure, hepatic cirrhosis, nephrotic syndrome) Redistributive hyponatremia (hyperglycemia, mannitol) Pseudohyponatremia (hyperlipidemia, hyperproteinemia, glycine solutions) Endocrine disorders (adrenal insufficiency, hypothyroidism)
Causes of hyperkalemia
Pseudohyperkalemia (hemolysis, prolonged use of tourniquet, marked leukocytosis)
Endogenous K (tumor lysis, rhabdomyolysis, exercise induced, burns)
Exogenous K (increased intake, transfusions)
Renal (insufficiency, chronic failure, oliguria, nephropathy)
Acidosis (metabolic raises K 0.7/0.1 pH, resp raises K 0.1/0.1 pH, diabetic ketoacidosis)
Drugs (succinylcholine, Beta blocker, digitalis, ACEI, heparin, cyclosporine,
spironolactone, amiloride, triamterene)
Endocrine (primary adrenal insufficiency, pseudohypoaldosteronism)
Hyperkalemic periodic paralysis (excitement, cold, fasting, stress, infection, GA)
Chronic hyperkalemia (decreased renal excretion)
Clinical features of hyperkalemia
Weakness, tingling, parathesias Flaccid paralysis Hypoventilation Cardiac toxicity (increased T waves, flattened P wave, AV conduction delay, QRS widening, v fib/flutter)
Treatment of hyperkalemia
Non emergent (reduce K intake, increase K output, IV loop and thiazide diuretics,
consider dialysis)
Emergent (calcium chloride centrally or calcium gluconate peripherally, sodium bicarb,
D50 plus insulin, albuterol)
Causes of hypokalemia
Redistribution of K into cells Metabolic alkalosis (decrease K 0.3/0.1 pH) Medications (insulin, epi and selective beta2 agonists) Hypokalemic periodic paralysis Potassium depletion Decreased dietary intake Extra renal (diarrhea, laxatives, intestinal bypass or fistula, vomiting and gastric suction) Renal (diuretics, steroids, PCN derivatives, renal tubular acidosis, diabetic keto, mineralocorticoid excess - hyperaldosteronism)
Clinical features of hypokalemia
Non cardiac (fatigue, myalgia, weakness, constipation, polydipsia and polyuria,
hypoventilation, paralysis)
Cardiac (arrhythmias, a fib, PVCs, flattening T waves, prominent U waves, ST depression,
prolonged QT, prolonged PR, widening QRS)
Treatment of hypokalemia
Correct underlying disorder
Asymptomatic or minor (oral K, encourage K rich diet)
Cardiac manifestations or severe (IV K ideally through central access)
Address possible hypomagnesemia
Causes of hypocalcemia
Parathyroid hormone deficiency Vitamin D deficiency Hyperphosphatemia (renal failure, tumor lysis, rhabdomyolysis) Renal failure Citrate toxicity Acute alkalemia Post cardiopulmonary bypass Acute pancreatitis
Clinical features of hypocalcemia
Cardiovascular (dysrrhythmias, QT prolongation, heart failure, hypotension, impaired beta
adrenergic action)
Neuromuscular (tetany, muscle spasm, papilledema, seizure, weakness, fatigue,
paresthesias, irritability, mental status changes)
Respiratory (apnea, laryngeal spasm, bronchospasm)
Psychiatric (anxiety, dementia, depression, psychosis)
Treatment of hypocalcemia
IV calcium Magnesium Correct metabolic and/or respiratory alkalosis Oral calcium or oral vitamin D Avoid hyperventilation Avoid bicarbonate
Causes of hypercalcemia
Malignancy (vast majority) Hyperparathyroidism Vitamin D intoxication Sarcoidosis Hyperthyroidism Immobilization Thiazide diuretics and lithium
Clinical features of hypercalcemia
Lethargy
Anorexia
Nausea
Polyuria
Neuromuscular (weakness, depression, impaired memory, emotional lability, lethargy,
stupor, coma)
Cardiovascular (hypertension, dysrhythmias, widening QRS, short QT, heart block, arrest)
Propofol infusion syndrome
More common in critically ill children Cardiomyopathy Rhabdomyolysis Severe metabolic acidosis Hyperkalemia Hepatomegaly Lipemia Renal Failure
Hypoxemia (pathophysiologic mechanism)
Decreased inspired oxygen (failure of anesthesia machine, disconnection, gas pressure
failure, crossing of tanks, etc)
Hypoventilation (esophageal intubation, ETT kinking, blockage, herniated or ruptured
cuff, right main stem intubation, respiratory depression)
Impaired diffusion
VQ mismatch
Right to left shunt (PFO, TOF)
Intrapulmonary derangements
Hypoxemia (structural anatomic)
Alveoli (pulmonary edema, acute lung injury, ARDS, pulmonary hemorrhage, PNA)
Interstitium (pulmonary fibrosis, viral PNA, allergic alveolitis)
Heart and pulmonary vasculature (PE, intracardiac or intrapulm shunt, CHF)
Airways (asthma, COPD, mucus plugging, right main stem intubation)
Pleura (PTX, pleural effusion)
Intraoperative Acute Hypoxia
Check color of patient
Check for a pulse
Check vital signs
Check for ETCO2
Take off ventilator and hand bag with 100% FIO2
Call for help
Check O2 monitor, peak airway pressure, and capnograph waveform
Listen to chest for bilateral breath sounds and chest rise
Evaluate ETT
Listen for wheezing
Bronchospasm - deepen anesthetic with volatile or give epi
Chest xray
Tension PTX
Presentation Unilateral absence of breath sounds Tracheal deviation Unexplainable hypotension Distended neck veins Treatment Find 2nd intercostal space Find midclavicular line Insert 14 gauge angiocath over top of the rib Listen for decompressive air rush Leave angiocath in place Place chest tube
Causes of hypercarbia
Increased production of CO2 Tourniquet release Aortic cross clamp release MH Sepsis Thyrotoxicosis Fever Decreased removal of CO2 Hypoventilation Airway Obstruction Increased Dead Space Rebreathing of CO2 due to mechanical malfunction Iatrogenic Sodium Bicarb administration Increased CO2 during laparoscopic procedure
Indications for Intubation
Mechanical Function Respiratory Rate >35 Vital capacity <15 ml/kg adult Vital capacity <10 ml/kg child Negative inspiratory force less than 20-25 cm H2O Gas Exchange Function PaO2 <60 on FiO2 of 50% A-a gradient >350 on FiO2 of 100% PaCO2 >55 Dead Space Ventilation/Tidal Volume (Vd/Vt) ration >0.6 Unstable Vital Signs Inability to protect airway
Indications for Extubation (subjective)
Subjective Resolution of acute disease Adequate cough Awake, alert, following commands Cooperative GCS >13 No sedation Sustained hand grip Sustained head lift >5 seconds Able to tolerate spontaneous ventilation Acceptable electrolytes Able to protect airway Clear oropharynx Adequate pain control Minimal end expiratory concentration of inhaled anesthetics
Indications for Extubation (objective)
Objective Vital Signs RR <30-35 Stable BP HR <140 Afebrile Gas Exchange PaO2 >60 PaCO2 <55 PaO2/FiO2 >150-300 Alveolar arterial PaO2 gradient <350 on 100% oxygen Maintenance of normal pH Mechanical FVC >10-15 ml/kg FEV1 >10 ml/kg TV >4-6 ml/kg Negative Inspiratory Force >20 VC >15 ml/kg Dead Space ventilation/Tidal Volume (Vd/Vt) <0.6 Rapid Shallow Breathing Index (RSBI) (f/Vt) <60-100 breaths/min Adequate hemoglobin No significant respiratory acidosis
Difficult Airway Algorithm
Look up Diagram
Pathological States that Predispose to Difficult Intubations
Congenital
Pierre-Robin (micrognathia, macroglossia, cleft palate)
Treacher-Collins (mandibular hypoplasia)
Down’s (macroglossia, atlantoaxial instability)
Kippel-Feil (restricted neck movement secondary to cervical vertebrae fusion)
Infection
Croup
Ludwigs angina
Abscess
Arthritis
Rheumatoid
Ankylosing spondylitis
Benign tumors
Malignancy
Injury (facial, cervical, laryngeal, tracheal, burns)
Diabetes
Scleroderma
Obesity
Pregnancy
Acromegaly
Anatomic abnormalities (micrognathia, limited jaw motion)
Criteria to Predict Difficult Airway
History (previous difficult, burns, edema, bleeding, airway stenosis, GERD, poor dentition,
radiation treatments)
Physical
General (obesity, cervical collar, traction device, external trauma, respiratory difficulty)
Patency of nares
Mouth opening (less than two finger breadths)
Teeth (prominent incisors, overbite, loose teeth)
Palate (high, narrow mouth)
Tongue
Prognathism
Thyromental distance <6cm
Neck (short and thick, limited extension, limited flexion)
Specific tests
Mallampati score of 3 or higher
Laryngoscopic grades III or IV
Radiographic assessments
Diabetic predictors (positive prayer sign - gap between palms)
Pediatric Airway - Differences
Larger occiput
Hypertrophied tonsil and adenoid tissue
More cephalad larynx (C2-3 premature, C3-4 infant, C4-5 adult)
More narrow and shorter epiglottis, angled into airway
Tongue larger in proportion to oral cavity
Cricoid cartilage is narrowest area (vocal cords in adult)
Obligate nasal breathers
Pediatric ETT selection
Uncuffed: Internal diameter (mm) = (16+age)/4
Pediatric Physiology - Pulmonary
Prone to peri-operative hypoxemia
High closing volumes
High MV/FRC ratio
Leads to rapid uptake of volatile
Faster inhalational induction (also greater cardiac output per kg)
Lower blood gas partition coefficient
Pliable rib cage
Diaphragm primary contributor to ventilation
If increased O2 demand
Increases RR
Increase respiratory excursion by diaphragmatic contraction
Leads to negative intra-thoracic pressure and retractions
Inefficient form of ventilation with high energy expense
Pediatric fluid maintenance and fluid deficit
Maintenance
4 ml/kg/hr for 1st 10 kg
2 ml/kg/hr for 2nd 10 kg
1 ml/kg/hr for each remaining kg
Deficit
Estimated = estimated hourly maintenance x number of hours NPO
Estimated Blood Volume
Premature 90 ml/kg Full term 85 ml/kg Infant 80 ml/kg Child 75 ml/kg Adult 70 (male) and 65 (female) ml/kg
NPO guidelines
Clear liquids: 2 hours Breast milk: 4 hours Formula: 6 hours Nonhuman milk: 6 hours Meal with fat: 8 hours
Risk Factors for Fetal Distress
Maternal Diabetes Pregnancy induced hypertension Previous stillbirth Infection Substance abuse C-section General anesthesia Chronic HTN Previous Rh sensitization Bleeding in 2nd or 3rd trimester Fetal Post term or preterm Poly or oligohydramnios Known fetal anomalies Abnormal fetal lie Non reassuring FHT Meconium stained amniotic fluid
Dyspnea - Differential Diagnosis
Obstruction to flow (asthma, emphysema, bronchitis, stenosis, malacia)
Resistance to lung expansion (fibrosis, restrictive disease
Resistance to chest expansion (pleural thickening, kyphoscoliosis, obesity, mass)
Weakness of pump (polio, neuromuscular disease)
PTX
Increased respiratory drive (hypoxemia, metabolic acidosis)
Psychological (anxiety, depression)
Dyspnea - Treatment Plan
Reduce the sense of effort Improve muscle function Decrease respiratory drive Alter CNS function Exercise training and pulmonary rehab
Tachypnea - Causes
Airway obstruction (extra or intra thoracic)
Anxiety/pain
Acute circulatory failure (CHF, cardiomyopathy)
Intrapulmonary (COPD, restrictive disease, asthma, aspiration, atelectasis, edema, PTX,
PE, pHTN)
Disease of chest wall or musculature (polio, MG)
Systemic Disease (sepsis, acidosis, hypoxia, shock, fever, MH, infection,
hypophosphatemia)
Excessive post exercise oxygen consumption
Hypermetabolic state
Hyperthyroidism
Wheezing - Differential Diagnosis
Bronchospasm Asthma COPD Tracheobronchitis Restrictive Pulmonary Disease RA associated bronchiolitis Extrinsic compression Intrinsic compression CHF PE Mechanical obstruction of ETT Inadequate depth of anesthesia Endobronchial intubation Pulmonary aspiration and edema PTX
Bronchospasm - Differential Diagnosis
Kinked ETT Solidified secretion or blood Pulmonary Edema Tension PTX Aspiration Pneumonitis PE Endobronchial intubation Persistent cough or strain Negative Pressure Expiration
Bronchospasm - Intraoperative Treatment
100% oxygen Deepen anesthetic Albuterol IV or SQ epinephrine Consider IV magnesium
Laryngospasm complications
Hypoxia
Noncardiogenic pulmonary edema
Cardiac arrest
Laryngospasm treatment plan
100% oxygen Remove irritating factor Jaw thrust Positive pressure ventilation Increase depth of anesthesia IV or topical lidocaine Call for help Succinylcholine (10-50 mg IV, IM, or SL) Attempt intubation
Stridor differential diagnosis
Inspiratory: upper airway obstruction
Expiratory: lower airway obstruction
Biphasic: mid tracheal lesion
Stridor treatment plan
Evaluate Rule out need for emergent intubation History Physical exam Chest Xray ABG Flexible bronchoscopy Consider ENT consult Oxygen - facemask Head up position Nebulized racemic epinephrine IV Dexamethasone (4-8 mg every 8-12 hours) Heliox
OSA - AHI index (Apena-hypoapnea)
Average number of apneas and hypoapneas per hour
Mild OSA: AHI 5-15
Moderate OSA: AHI 16-30
Severe OSA: AHI >30
OSA - Peri operative concerns
Increased risk for difficult intubation Post-operative hypoxemia Post-operative airway obstruction Myocardial Ischemia Arrhythmia Death
One Lung Ventilation - Indications
Absolute
Isolation to prevent spillage (infection, hemorrhage)
Control of ventilation (bronchopleural fistula, surgical opening of conducting airway,
cyst, tracheobronchial tree disruption, life threatening hypoxemia from unilateral
airway disease)
Unilateral bronchopulmonary lavage
Relative
Surgical exposure (thoracic aortic aneurysm, pneumonectomy, upper lobectomy,
mediastinal exposure, thoracoscopy, middle and lower lobectomies, esophageal
resection, thoracic spine surgery)
Severe hypoxemia from unilateral lung disease