Comp Exam III Flashcards
Drug and dose to treat post-op shivering
Meperidine (Demerol)
25mg IV
Primary cause of post-op shivering
Pre-operative Hypothermia
Post-op MI is the strongest predictor of what?
Preoperative cardiac morbidity
MH: 4 early signs
Unexplained increase in ETCO2
Muscle RIgidity
Tachycardia
Increased Temp
Respiratory: 4 effects/goals of PEEP
Increased FRC by preventing alveolar collapse
Decreased atelectasis and subsequent intrapulmonary shunt
Minimize atelectotrauma
Optimize pulmonary compliance
How does Preoxygenation affect oxygen reserve time
Provides a patient with roughly 5-8 mins of oxygen reserve
Up to 90% of FRC (2L) is filled with oxygen
Normal O2 demand is around 200-250 ml/min
Respiratory: effects of volatile agents
Dose-Dependent depression of ventilation
Decreased TV (Causes decreased MV)
Increased RR
Resp. drive response to hypoxemia is abolished at MAC >1
NS contents
Equal parts NS and Cl (154 mmol/L each)
Osmolarity 308 (Isotonic)
pH: 4.5-7
Intraop Monitoring: 1 twitch (TOF monitoring)
Single pulse delivered at 1-0.1 HZ (Every 1-10 seconds)
Each Stimuli lasts .2msec
Positioning for a nephrectomy
Lateral flexed position
Axillary roll is placed beneath the dependent upper chest to minimize risk of brachial plexus injury
This position is associated with adverse respiratory and circulatory effects
ASA Standard Monitoring
NIBP Cuff
Temp
EKG
SPO2
Most commonly injured nerve in Lithotomy position
Common Peroneal (Fibular)
Trendelenburg positioning effects on the lungs
Decreased FRC
Decreased Lung Compliance
Significant Atelectasis
Increased peak airway pressure (Can lead to barotrauma)
What NMB causes Histamine release?
Succinylcholine
Atracurium
Mivacurium
Gantacurium
Low-Dose Dopamine Dose
0.5-3 mcg/kg/min
Low-Dose Dopamine Effects
stimulates D1 receptors; causes vasodilation of renal vasculature/promotes diuresis
Moderate Dose Dopamine
moderate doses (3-10 mcg/kg/min)
Moderate Dopamine Effects
stimulates beta-1 receptors; causes inc. myocardial contractility, HR, SBP, and CO
High Dose Dopamine
high dose (10-20 mcg/kg/min)
High Dose Dopamine Effects
stimulates alpha-1 receptors; inc. PVR and dec. renal blood flow
most commonly injured nerves during patient positioning
ulnar nerve and brachial plexus
-due to arms out > 90º or falling off armboard (more of a concern in deep trendelenburg)
what patient position is directly associated with increased intraocular AND intracranial pressure
Steep Trendelenburg
lithotomy position: common procedures and physiological effect
-commonly used for GYN, urology, and rectal procedures
-dec. FRC/lung compliance
-inc. venous return and CO when raising legs
recovery from NMBs: head lift time
At least 5 seconds
cardiovascular: effects of volatile agents
-dec. BP
-dec. SVR (except halothane)
-dec. CO (except isoflurane and minimally by desflurane)
-cardiac protective effects via ischemic preconditioning
-N2O has no cardiovascular effects!
positioning: posterior fossa
craniotomy of the posterior skull
-can be done in prone or beach-chair position
-mayfield pins are used (causes acute inc. in BP when pins are positioned)
intraop monitoring: 10 physiologic effects of hypothermia
-cardiac arrhythmias and ischemia
-inc. PVR
-LEFT shift of Hgb-O2 saturation curve
-reversible coagulopathy (platelet dysfunction)
-inc. post-op protein catabolism and stress response
-altered mental status
-impaired renal function
-delayed drug metabolism
-impaired wound healing
-inc. risk of infection
lithotomy position: considerations when positioning and common complications
-flex legs 90º and abduct 30º at hip joint
-raise/lower legs at same time to avoid lumbar torsion
-common complications: common peroneal nerve injury and venous thrombosis due to obstructed venous drainage
Advantages of Rocuronium
-suitable alternative to succ for RSI
-no metabolism and eliminated primarily by liver–> no active metabolite
intraop monitoring: 6 causes of ETCO2 increase
-hypoventilation
-rebreathing of CO2
-iatrogenic administration of CO2 (ex. from lap insuflation)
-bicarbonate administration
-tourniquet release
-sepsis or other hyper metabolic conditions (fever, MH, thyroid storm)
LR Contents
-Na (130) > Cl (109) > lactate (28) > K (4) > Ca (1.4)
-osmolarity: 273 (isotonic)
-pH: 6-7.5
at what platelet count is transfusion indicated
-normal patients < 10,000-20,000
-thrombocytopenic patients < 50,000
-1 unit inc. platelet count by approx. 5,000-10,000
positioning: axillary roll
placed BELOW the axilla/armpit to protect brachial plexus
-supports the thorax and prevents compression of lower arm
IV fluids with transfusion
crystalloids or colloids can be infused simultaneously through a second IV line for volume replacement
succinylcholine side effects with defasciculating dose of NDNMB
helps prevent fasciculations and dec. post-op myalgias
pulse ox law
pulse oximetry is based on Lambert-beer law
Lambert-Beer Law
oxygenated and deoxygenated hemoglobin differ in their absorption of red and infrared light: oxyhemoglobin absorbs more infrared light (940nm) and deoxyhemoglobin absorbs more red light (660 nm)
5 Patient risk factors for positioning
-thin or morbidly obese
-dec. blood flow: vascular diseases (smoking) , ischemia, and hypotension
-advanced age (dec. mobility)
-diabetes
-long procedures
central line positioning
optimal location of catheter tip is just superior to or at junction of the superior vena cava and right atrium
most commonly injured nerve in lateral decubitis position
brachial plexus (protect w/ axillary roll!!)
-also radial and common peroneal
cardiovascular: effects of desflurane
rapid inc. in desflurane conc. can cause transient (but sometimes worrisome) inc. in HR, BP, and catecholamine levels
plasmalyte contents
-Na (140) > Cl (98) > acetate (27) > gluconate (23) > K (5) > Mg (1.5)
-osmolarity: 295 (isotonic)
-pH: 4-8 (7.4)
succinylcholine hyperkalemia
-serum potassium inc. by 0.5 mEq/L
-this can be catastrophic in pt’s with preexisting hyperkalemia: burn injury, massive trauma, severe chronic infection, and neurological disorder (stroke, Parkinson’s, etc., muscular denervation, muscular dystrophy)
Remifentanil Half-Life
approx. 3 minutes regardless of infusion duration (lacks context sensitivity)
How is remifentanil metabolized
Rapid degradation by plasma esterases
When are bite blocks required
needed in prone position to secure ETT or any surgery in which MEPs are monitored
Hypokalemia on an EKG
-inc. P wave height/peaked
-prolonged PR interval
-prolonged QT
-shorter and flattened or inverted T wave
-ST depression
-U waves
Describe this ECG
Hypokalemia
Describe this ECG
Normokalemia
Prone position risks
Post-op blindness (ischemic optic neuropathy)
prone position effects on ventilation
Improved ventilatory effect
increased FRC
Prone position cardiac effects
Decrease in Cardiac Output, venous return, and LV Compliance
4 Body heat loss routes
Radiation
Convection
Evaporation
Conduction
Which body heat loss route is most common
Radiation
Which body heat loss route is 2nd most common?
Conduction
How does the epinephrine dose change which receptor will be effected?
Small doses are going to agonize Beta 2
Medium Doses will agonize Beta 1
Large doses will agonize Alpha and Beta
Small Dose Epi
1-2 mcg/min
Small dose epi receptor
Beta 2 Agonist
Medium Dose EPi
4 mcg/min
Medium Dose Epi Receptor
Beta 1 Agonist
Large Dose EPi
10-20 mcg/min
Large Dose Epi Receptor
Alpha and Beta agonist
What can cause Pulse Oximetry interference?
Methemoglobinemia
Methylene Blue dye use
Other artifacts
Methemoglobinemia effects on SpO2
Carbon Monoxide poisoning can result in methemoglobinemia, causing a false 85% reading on the SPO2 monitor
How does methylene blue affect SpO2 readings
Blue dye causes falsely low readings
What artifacts can affect SpO2
Excessive ambient light
Motion
Low perfusion
What 4 ECG Artifacts can simulate arrhythmias?
Patient or lead wire movement
Electrocautery use
60-hz interference from nearby alternating current devices
Faulty electrodes
What is a common cause of mainstem intubation?
Happens during patient positioning because increased head flexion causes increased tube depth
What does mainstem intubation present as?
Increased PIP
Decreased Saturation
No change in ETCO2
When must an arterial line be zeroed?
Any time the patient is moved if the patient is not moved in tandem
Where should an arterial line be zeroed?
At the body level that is being monitored:
ex. at ear level to measure cerebral/circle of willis Pressure
True or false: Transducer measurements in arterial lines are static
False
They drift over time.
Zeroing should be done regularly
Parkinson’s Comorbidities
HTN, ischemic heart disease, musculoskeletal disorders, HLD, and diabetes
(plus psychiatric comorbidities: depression, sleep disorders, cognitive impairment anxiety)
Medications contraindicated in Parkinson’s patients
Avoid metoclopramide/reglan, anti-dopaminergic drugs, and succinylcholine (more susceptible to hyperkalemia)
How do we check recovery from NMBs?
Sustained Tetany for 5 sec
Sustained head life for 5 sec
Inspiratory force (At least -25cm H2O)
Vital Capacity
Tidal Volume
What 11 things will LOWER MAC?
hypothermia
Hyperthermia
Elderly
Acute alcohol use
Anemia Hct<10
Hypoxia (PaO2<40)
Hypercarbia (PaCo2>95)
MAP <40
Hypercalcemia
Hyponatremia
All anesthetic drugs except ephedrine
Chronic Amphetamine use
Core Temp Monitoring Goals
Maintain temp >=36 C
What is the gold standard for Core temperature monitoring
Pulmonary Artery
Core Temp Locations
Pulmonary Artery Catheter
Distal Esophagus
Nasopharyngeal
Tympanic Membrane
What properties about desflurane would make it a good mask induction agent?
low solubility in blood and body tissue cause very rapid induction and emergence
What properties of Desflurane make it a bad induction agent?
pungency, airway irritation, and inc. airway resistance in children w/ reactive airway susceptibility (associated w/ more coughing, breath-holding, and laryngospasms)
Anticholinesterase (Like Neostigmine) side effects
SLUDGE BB
Salivation
Lacrimation
Urination
Defecation
GI Upset
Emesis
Bronchoconstriction
Bradycardia
4 Consequences of intra-op Hypothermia
Increased Cardiovascular morbidity
Increased risk of wound infection (Dec. temp 1.9C triples incidence of wound infection
increased risk of bleeding
Prolonged anesthesia recovery time
Considerations that must be taken into account for patients in NORA for MRI Procedures
-must exclude all ferromagnetic materials from magnet area
-all anesthesia equipment must be compatible with the scanner
-patients must be free of implants that could interact with the magnet (ex. pacemaker)
use and disadvantage of ECG monitoring filters
used to reduce “motion” artifact
-lead to distortion of the ST segment and may impede diagnosis of ischemia
train of four Hz
2 Hz (4 stimuli in 2 secs, each for a 200 microseconds/.2 msec duration)
increased resistance to succinylcholine occurs in what instances?
-myasthenia gravis (or any condition associated w/ fewer ACh receptors)
-dibucaine-resistant variant allele (or any pt w/ abnormal pseudocholinesterase genes)
succinylcholine termination of action
metabolized by pseudocholinesterase into succinylmonocholine in plasma and liver
MAC anesthetic requirements by age
dec. by 6% per decade of age
Which 2 leads are used for ECG ischemia detection
-mainly V5 (anterior and lateral wall ischemia)
-lead II (arrhythmias mainly, but also inferior wall ischemia)
4 consequences of shivering
Increased O2 consumption by 200%
Increased sympathetic activation
increased intracranial and intraocular pressure
Aggravate wounds from stretching
