Peri-operative Flashcards
Discuss the general anesthetic procedure
Pre-oxygenate patient using oxygen mask -> administer IV induction medication -> brief-bag-mask ventilation -> endotracheal intubation
Discuss the indications for endotracheal intubation
5 Ps
- Patent airway
- Protect against aspiration
- Positive pressure ventilation
- Pulmonary toilet (suction)
- Pharmacologic administration
- Hemodynamic Instability
Discuss the airway management equipment
STABLES
- Suction
- Tape
- Airway for bag-mask ventilation
- Bag mask and oxygen
- Laryngoscope
- Endotracheal tube with stylet (7-8 men, 6-7 women, age/4+4 for children)
- Syringes for medication
Discuss the procedure for bag-mask ventilation
- most important airway management tool Indications - hypoventilation - severe hypoxia Contraindications - prolonged or high pressure BMV contraindicated for patient with full stomach Procedure - sniffing position: cervical flexion with atlanto-occipital extension - C to secure mask on face - E to secure and lift jaw Troubleshooting - suction - chin lift and jaw thrust - oral or nasal airway
Discuss the procedure for endotracheal intubation
Preparation - prepare all equipment - ensure O2 source and monitors available - apply monitoring - position in sniffing position - pre-oxygenate - administer induction medication Intubate - introduce laryngoscope to sweep tongue and insert posterior to vallecula - raise handle to visualize cords - place tube 1-2cm below cords and inflate cuff Confirm Placement - tube visualized - detection of CO2 on end tidal CO2 between 30-35 - auscultation of lungs - Observed chest rise - Condensation on ET tube - refilling resevoir on bag
Discuss laryngeal mask airway
Indication
- when general anesthesia required but ETT is not
- rescue when intubation and bag-mask fail
- assistive device
Absolute Contraindications
- ventilation requiring high pressure (>20) [obesity, lung disease]
- high risk for aspiration
Relative Contraindications
- patient with mass in airway
- patient position for surgery is not supine
- surgery lasting >2-3hrs
Discuss the procedure for general anesthesia
- Pre-oxygenate with oxygen mask until expire oxygen >80%
- IV infusion of induction agent (propofol 1mg/kg) plus muscle relaxant and pain medication
- Wait until patient is under anesthesia (unresponsive, no reflexes/no blink reflex)
- Bag mask ventilate and administer muscle relaxant (rocurronium 1mg/kg - takes 90sec)
- Intubate and attach ETT to ventilator
Discuss the difficult airway algorithm
Known Difficulty Airway
- awake intubation
- if fail cancel case or use supra-glottic device (LMA) or regional anesthesia if possible
Unknown Difficult Airway and Fail
- bag mask valve
- if BMV successful then can attempt different airway (video-assisted, supra-glottic, fiberoptic)
- if fail second way then wait for anesthetic to wear off and cancel case
- if BMV unsuccessful then call for help, attempt supra-glottic airway, or emergency airway
Discuss the exam and investigations for hypovolemia
History - poor intake - excessive diuretic use - GI or blood loss Exam - tachycardia - Orthostatic hypotension - low JVP - dry mucous membrane - decreased skin tugor - low urine output (<0.5mL/kg/hr) Investigations - high urea to creatinine (10:1) - urine sodium <20mmol/L and fractional excretion Na <1% - fractional excretion urea <35% - increased urine osmolality - increased hematocrit - metabolic alkalosis in mild and metabolic acidosis in severe
Discuss the goals of IV fluid administration in anesthesia
- optimize pre-operative volume status
- compensate for losses
- normalize electrolyte status
- treat critical illness/events
Ways to Increase Speed - short IV catheter
- larger bore IV catheter
- high bag height
- pressurized device
Discuss types of IV crystalloids and replacement
Normal Saline: 0.9% normal saline D5W: 50g/L dextrose in water 2/3-1/3: 2/3 D5W and 1/3 NS - 33g/L glucose and 50mEq Na and Cl/L Ringer's Lactate: 130mEq Na, 109mEq Cl, plus small K, Ca and lactate Replacement - RL best for resuscitation - as 2/3 interstitial and 1/3 intravascular require 3:1 for replacement of blood loss - D5W goes 2/3 ICF and 1/3 ECF
Discuss general indications for specific IV fluids
Hypovolemia - NS or RL - D5W least effective as majority goes into intracellular fluid Cirrhosis with hypovolemia - albumin Dehydration (hypovolemia with hyponatremia) - hypotonic saline (0.2NS or 0.45NS) - D5W - done to move fluid into intracellular space Maintenace - 0.45NS, D5W - 2/3-1/3 - 0.45NS plus 20mEq/L of KCl added to replinish water and electrolytes Blood loss - NS or RL - pRBC
Discuss massive transfusion protocol
- Occurs when patient has lost entire blood volume within 24hrs
- Require 4units pRBC for each volume blood lost
- Give 1 FFP for every 2u
- Require frequent monitoring of CBC, electrolytes (Ca included), INR and fibrinogen
Discuss Complications following blood transfusion
Infection
- viral most common
Hemolysis
- Immediate reaction due to ABO incompatibility
- fever, chills, chest, or flank pain, hypoxemia, hypotension, ARF and FIC
- delayed reaction at 7-21d due to trace antibodies
Non-Hemolytic Febrile Reaction
- reaction to donor leukocyte antigens and antibodies
- fever, chills, N/V, headache, myalgia
Allergy
- react to proteins in blood
Immune System
- more commonly in immunocompromised individuals
Coagulopathy
- Dilution of coagulation factors and platelets when massive transfusion of pRBC
Transfusion Associated Circulatory Overload (TACO)
- congestive heart failure and acute pulmonary edema
Transfusion Related Acute Lung Injury
- result in Acute respiratory distress syndrome (hypoxemia, dyspnea, hypotension)
Hyperkalemia
- increase K concentration in blood
- peaked T waves, wide QRS, loss of p wave
Hypocalcemia
- citrate binds to calcium
- decreased myocardial contractility, hypotension, widened QRS and bleeding
Acid-Base Abnormalities
- metabolic acidosis: citric acid and lactic acid in stored blood
- metabolic alkalosis: hepatic metabolism of citric acid into bicarbonate
Discuss type, screen and crossmatch for blood products
Type
- confirms ABO and Rh blood groups
Screen
- takes 5-10 minutes which screen for presence of antibodies
Crossmatch
- taks 45 minutes and mixes blood together to determine if reaction occurs
Discuss the indications for blood products
- 1 unit is 280mL which should raise Hgb 10g/L
Patient Consent
Anemia: Acute or Chronic - acute anemia require transfusion
Trajectory of Active Uncontrolled Bleeding
Presence of CAD or CVD - limited compensatory mechanism so require Hgb >100
Evidence of Ischemia or Coagulopathy
Blood loss Exceed Estimated Acceptable Blood Loss - Acceptable blood loss = EBV (75mL/kg male, 65mL/kg female *kg) * [Pre-op Hgb - Transfusion Trigger Hgb]/Pre-op Hgb]
- usually <70 require transfusion
Discuss the indications for fresh frozen plasma, platelets, and cryoprecipitate
Fresh Frozen Plasma
- Factors 2/5/7/8/9/10/11 protein C/S, fibrinogen, anti-thrombin 3
- pre-op for those with coagulation disorders
- massive transfusion
- reversal of warfarin
Platelets
- Severe thrombocytopenia <10 in non-bleeding
- Mild 20-50 in bleeding
- Surgery with >500mL of bleeding and platelets <50
- patients with head injury or prior to neurosurgical procedure with platelets <100
- large volume pRBC (>6)
Cryoprecipitate
- factor 2/8/13, fibrinogen, von Willebrand Factor
- DIC
- Massive bleed with fibrinogen <1
Discuss the calculation for deficit losses
Estimate Hypovolemia
- Mild 3% (dry axilla and mucous membrane
- Moderate 6% (oliguria, othostatic hypotension, cool peripheries)
- Severe 9% (profound oliguria, CNS dysfunction)
Estimate Total Body Water
- Male 60% body weight
- Female 50% body weight
- Elderly 45% body weight
Calculation
- kgEstimate Total Body WaterEstimate Hypovolemia
- Replace first half in first 8hrs and second half in next 16hrs
Discuss volume control as a mode of ventilation
Indication
- used for patients with normal and constant lung volumes
Constant Features
- RR (end tidal CO2 to 35-45)
- Positive end-expiratory pressure (PEEP, >0)
- positive pressure in airway at end of expiration
- Tidal volume (VT =7mL/kg)
- volume of air moved in one breath
Advantage
- as VT is set ensures adequate ventilation and maintains PaCO2 and pH
Risk
- pressure needed to maintain VT may change leading to barotrauma
Discuss pressure control as a mode of ventilation
Indication
- abnormal lung compliances or where lung compliance may change (position)
Constant Features
- RR
- PEEP
- Peak Inspiratory Pressure (PIP) which is proportional to tidal volume/lung compliance and set to ideal tidal volume of 7mL/kg
- pressure in airway during inspiration
Advantage
- set pressure control preventing barotrauma
Disadvantage
- tidal volume may change per breath leading to either volume trauma or inadequate ventilation
Discuss synchronized intermittent mandatory control as a mode of ventilation
Indication
- weaning from volume control ventilation
Constant Features
- minimum tidal volume
- RR
- pressure support
Advantage
- if patient breaths on their own then machine delivers supporting pressure to help
- if do not breath machine will provide breath of minimum tidal volume
Discuss pressure support ventilation as a mode of ventilation
Indication - weaning patient off pressure control ventilation Constant Features - Minimum PIP - Minimum RR - Pressure support Advantages - if do not breath machine provides minimum inspired pressure
Discuss the criteria for extubation
- Underlying cause for initial intubation addressed
- No anticipated future need of intubation
- Hemodynamically stable
- Well oxygenated
- Respiratory effort based on end tidal CO2, visible chest rise
- Adequate level of consciousness (gagging, obeying command, moving limbs)
- Adequate muscle tone (squeeze hand, ability to lift head)
