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108 Cards in this Set
- Front
- Back
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Three reasons for performing peripheral nerve blocks
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-anesthesia
-postop analgesia -diagnosis and tx of chronic pain syndromes |
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Recommendations regarding peripheral nerve block for paresthesias:
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if paresthesia occurs, don't inject LA -> increased chance of nerve damage
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sfx and complications of cervical plexus/interscalene blocks (x10)
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Temporary nerve palsies:
-Horner's syndrome -phrenic nerve block -brachial plexus block -RLN block Wrong location: -intravasc injection -epidural/spinal injection Other -LA tox -infection/bleeding/hematoma |
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Major risk unique to supraclavicular block
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PTX
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why are supraclavicular blocks more successful than axillary blocks?
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-supraclav can be performed with arm in any position
-nerves closer together in supraclav region than in axillary region |
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why are supraclav/interscalene blocks less preferred in pts with COPD?
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phrenic nerve block (relatively common) can result in dyspnea or respiratory insufficiency
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complex regional pain syndromes involving the arm are commonly treated by what kind of block?
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stellate ganglion block
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Bier block (IV regional anesthesia = IVRA)
1. how high is tourniquet inflated above SBP? 2. maximum duration? |
1. tourniquet = [100 mmHg > SBP] or 2-2.5x SBP
2. max duration = 1 hour |
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Contraindications to tourniquet on an extremity for a prolonged period (ie, for Bier block)?
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sickle cell
hypercoagulability neuropathy in involved extr infxn under tourniquet site vascular graft in extremity |
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Principle risk of IVRA (Bier block) and prevention?
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main risk
systemic toxicity from LA after tourniquet deflation prevention: tourniquet should not be deflated for 20-30 minutes following injection, even if surgery has ended (time for LA to be metabolized |
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See Baby Miller, figure 30-2, and explain each of the lines
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(see text)
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Which of the following increases ICP the most on a dose-related basis?
a. Ketamine b. BDZ c. Narcotics d. Inhalation agents |
**Inhalation agents** cause greatest increases in ICP
(2/2 potent cerebral vasodilation) |
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8x s/s of increased ICP
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-HA
-nausea/vomiting -HTN -bradycardia -AMS -abn breathing -szs -papilledema |
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Cushing's triad =
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-bradycardia
-HTN -increased ICP mech: incr ICP -> decr CPP -> incr MAP as body tries to incr CPP -> reflexive bradycardia |
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Given a pt with blood glucose 490, why would it be inadvisable to give a large IV bolus of insulin?
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cerebral edema
insulin bolus -> cellular uptake of glucose -> blood hypoosmolar relative to brain tissue -> influx of water into brain -> cerebral edema |
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why is air embolism more common in the following?
-surgeries w/ T-berg or reverse t-berg? -CS where uterus is externalized -LSC surgery? |
-tilted surgeries increase chance of air entrainment...craniotomies the worst b/c vessels tented open
-LSC: pressurized CO2 insufflation |
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Mgmt:
CO2 or air embolism |
-stop source of air
(irrigate field or stop insufflation; crani-> IJ pressure) -stop N2O to prevent expansion of air embolus -if possible, pt to LLD to move air to R heart (preventing PA occlusion) -if massive, central line to remove air with syringe -O2, fluids, CV meds - ie manage hypoxemia, dysrhythmia, hypoTN |
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for pts with carotid stenosis, at what level would you maintain PetCO2 and BP?
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PetCO2 and BP high (MAP = 70) to create a pressure head proximal to the stenosis
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What muscle relaxant contraindicated in the following pts?
-massive neuro injury -progressive neuromuscular dz -massive trauma -bedridden -hx of MH |
succinylcholine
upregulation of ACh receptors throughout muscle -> ↑↑↑ metabolism in response to stim -> rhabdo, hyperkalemia (->) cardiac arrest |
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what is autonomic hyperreflexia and what level of spinal injury is it associated with?
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Anatomy: Spinal cord injury T7 or above
Stimulus: Cutaneous, visceral (bladder), proprioceptive, below the level of the lesion Etiology: Spinal reflex which is normally inhibited by descending feedback Result: HTN followed by overzealous vagal response (brady, heart block, vasodilation) |
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what is the supine hypoTN syndrome and how can it be avoided
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3T pregnant woman:
supine position -> gravid uterus re/in aortocaval compression -> hypoTN -> nausea, dizziness prevent by lying to the side, lateral manual displacement |
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pregnant women - 6 wks postpart can show prolonged response from which paralytic?
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succinylcholine
occurs 2/2 decreased plasma concentration of pseudocholinesterase |
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If GA required for CS, describe steps to securing the airway
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-RSI + immediate ETI (all pts at risk of aspiration)
RSI: -oral bicitra, preox, cricoid pressure, IV anesthetic + NMBD -NO MASK, straight to DL with ETI and inflation of cuff |
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in term pregnant patients, what happens to the following physiologic parameters?
PaCO2 Hgb FRC TV |
PaCO2 - decr 2/2 incr frequency
Hgb - decr 2/2 physiologic hemodilution FRC - decr 2/2 cephalad mvmt of diaphragm TV - incr 2/2 progesterone and incr VCO2 |
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2x anesthetic agents that cause uterine relaxation + situations in which desirable?
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2x: vapor, NTG
situations: attempting to deliver baby/placenta; can cause atony |
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What is HELLP syndrome?
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variant of severe pre-x
Hemolysis Elevated Liver enzymes Low Platelets proposed mech: (?placental abn?) -> hepatic inflammation -> abn coag cascade -> MHA (->) coagulopathy |
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PreX commonly treated with Mg.
This can lead to prolongation of the effects of what anesthetic drugs? |
non-depol NMBD
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Which pts are more likely to have PPH and should therefore have T+C with incr IV access? (x)
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ATONY most common cause of PPH -> what causes atony?
-multi gestation -big baby Others -previa (vasa/placenta) -abruption -hx of uterine surgery -coagulopathy |
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DDX:
Intraop CS, sudden drop in PetCO2, BP, SpO2 |
-Hge
-air embolism -AFE -PE -low CO state |
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If a 2T pt presents for emergency appendectomy, what should she be told about teratogenicity of anesthetics and chances of PTL?
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single exposure to anesthetic agents not assoc with teratogenicity or PTL
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incidence of major hemolytic txf reaction from one unit of bank blood for:
a. untested blood b. type specific blood c. crossmatched blood |
Risk: 1/
a. 100 b. 1000 c. 10K - 35K |
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60yo F PMHx obesity, renal failure, OA undergoing difficult repeat THA under GA
Preop labs Hgb 10.5, BUN 59, Cr 3, K 3.8 Pt's blood loss requires 1U autologous blood -> is this pt at risk of major transfusion? |
"patient must still be crossmatched on the day of surgery for his autologous unit, which then must be checked on the day of surgery. Error is always possible."
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What solutions (x2) can be used to dilute pRBCs to decrease viscosity before infusion?
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NS/normosol
Theoretically, cannot use LR because ppts with citrate in banked blood. NN says in his lecture that there is so much CPDA in blood relative to Ca in LR that this makes no difference. |
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If a pt gets 3U of O-neg blood, should they get their type or continue to get O-neg? Why?
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Stick with O-neg
Switching could cause intravascular hemolysis of type-specific blood 2/2 anti-A and anti-B Abs in O-neg |
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a. most common adverse txf reaction?
b.other types x2? |
a. febrile transfusion reaction (1/100-200)
b. allergic - fever, pruritus, urticaria hemolytic - chills, lumbar/sternal pain, fever, dyspnea, hyponatremia, hematuria, petechiae |
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txf effects of 2,3-DPG and effects on O2Hgb dissoc curve?
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banked RBCs have lower levels of 2,3-DPG
2,3-DPG normally shifts curve to R -> lower Hgb-O2 affinity -> improved O2 delivery to tissues therefore banked blood shifts O2Hgb curve to R -> more difficult to release O2 to tissues |
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Which banked product results in the greatest drop in pt's Ca2+ level?
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FFP
high levels of CPDA citrate, which is a Ca binder, to prevent clotting inside the unit |
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normovolemic hemodilution
a. what is it? b. indications c. contraindications |
a. at the start of a case with anticipated blood loss, draw off pt's blood for later replacement and replace with crystalloid/colloid to Hct 27-33%
b. indications: - difficult blood type to crossmatch -refusal of non-autologous blood -large rapid blood loss anticipated (elective procedure) c. contraindications -sickle cell disease -major organ dz where O2 carrying capacity can't be compromised |
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TRALI
a. what is it? b. mgmt |
a. RDS usually >=6h after txf 2/2 noncardiogenic pulm edema; most common cause of txf-related fatality
b. mgmt -stop blood product -support hemodynamics -CXR/CBC -notify blood bank |
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therapy for hemolytic reaction
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-stop txf
-send blood and sample of pt's blood back to bank -IVFs (support BP) titrated to UOP (prevent renal failure) -monitor for hyperK -monitor renal fnc and coag profile (rationale?) |
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when arterial pH < 7.1, effects on myocardial contractility and SNS?
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decr myocardial contractility
incr catecholamine release |
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describe mech by which low pH causes a change in ventilation?
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low pH (incr H+) -> incr H2CO3 -> incr CO2 -> central chemoreceptors -> increased TV and f -> incr MV
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Could a patient mechanically ventilated to achieve normal minute ventilation develop respiratory acidosis?
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-nonfunctional inspiratory valve
-exhausted CO2 scrubber -pulmonary disease with increased dead space ventilation |
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Describe fx of hyperventilation on electrolytes
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hypoK (2/2 bicarb-K exchange)
hypoCa (tetany) |
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effects of hypervent on the following:
a. cerebral vessel diameter b. coronary vessel diameter c. O2-Hgb dissoc curve |
-cerebral vasoconstriction
-coronary vasoconstriction -L shifted O2Hgb dissoc curve |
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how much does pH change for acute alteration of 10mmHg in PCO2?
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PaCO2 INCR -> 0.8 mmHg drop in pH
PaCO2 DECR -> 0.5 mmHg rise in pH |
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Formula for A-a gradient?
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(A-a) = PAO2 - PaO2
PAO2 = FiO2(PB-PH2O) - PaCO2/RQ |
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How do heparin, sample temp, and air bubbles affect ABG measurements?
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heparin can decr pH
cold sample -> decr PO2/PCO2 but nml HCO3 --HIGHER pH in the pt (who is cold) than in the sample (which must be warmed to 37C for testing) air bubbles -> inaccuracy in PO2/PCO2 measurements |
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disadvantages of acute postop pain?
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htn/tachycardia -> myocardial ischemia
splinting -> atelectasis, hypoxemia tachycardia |
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advantages of PCA
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-more immediate pain relief
-less total drug dose -less sedation -fewer nocturnal disturbances (better sleep) -improved pt satisfaction |
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effect of neuraxial opioids on respiration (and mechanisms)?
ie, early and late effects |
early depression: systemic absorption
delayed depression: cephalad spread of opioid in CSF highly lipid-soluble opioids (fentanyl) less likely to cause resp depression than morphine |
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advantages of neuraxial anesthesia
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-excellent analgesia
-faster mobilization -fewer pulm complications -(decr CV and infectious complications) -improved sleep quality |
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psych disturbances assoc w chronic pain?
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depression, anxiety, (hostility)
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neurolytic blocks with phenol or alcohol should only be used in what population?
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Ca pts with unrelenting pain who have life expectancy of months-weeks
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How does a TENS unit (for spinal cord stimulation) work?
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direct activation of ascending fibers in the dorsal columns by a pacemaker-like pulse generator helps relieve chronic pain.
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Complex regional pain syndromes:
give the two types, and the tx options available for both |
CRPS Type I: persistent pain with sympathetic dysfunction occurs without an identifiable nerve injury (eg after severe ankle sprain)
Tx: LA block of SNS, physiotherapy, TENS, IV guanethadine or phentolamine ----- CRPS Type II: persistent pain after identifiable nerve injury (eg GSW to brachial plexus) Tx: LA blocks of SNS |
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most cardiac depressant volatile?
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halothane
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effects of iso/des/sevo on:
a. BP/HR b. breathing |
a. Decr BP -> reflex incr HR
b. rapid shallow breathing |
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4x effects of vapor on resp system,
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1. decr VT incr f -> rapid shallow breahting
2. decr bronchial VSMC tone 3. inhibits HPV 4. vapor = bronchial irritants (can re/in cough, breath holding, spasm) (des > iso > halo >> sevo) |
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define MAC of a gas
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minimum alveolar concentration
concentration (in vol%) of a gas in the alveolus at which 50% of healthy volunteers remain immobile to surgical stimulus |
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name some situations where the pt is volume down before surgery
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-trauma
-vomiting/diarrhea/bowel prep -chronic HTN -diuretics -sepsis -elderly |
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physical signs of hypovolemia
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-decr BP/reflex tach
-orthostasis -oliguria -skin/membrane changes |
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give reasons why pts need more fluids when under GA?
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1. deficit (NPO status)
2. maintenance rate (baseline needs) 3. insensible losses 4. surgical blood loss though "third spacing" is frequently cited, this is a myth; see Jacob et al, Best Prac Res Clin Anesth. 23 (2009). |
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Type, screen and crossmatch
What is each one, and what good for? |
TYPE: pt's blood with commercial plasma
Tests for ABO group/Rh status SCREEN: pt's plasma with commercial blood Tests for pt Abs to blood group Ags CROSSMATCH: pt's plasma with donor blood tests for minor antigen incompatibility and Abs |
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incidence of selected txf complications (1/...)
febrile rxn Hep B HTLV WNV HCV HIV acute hemolytic rxn |
incidence of selected txf complications (1/...)
febrile rxn 100-200 Hep B 220K HTLV 640K WNV 1M HCV 1.6M HIV 1.8M acute hemolytic rxn 10K-35K (but 1/20 fatal) |
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massive txf results in lower levels fo these coagulation components x5:
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fibrinogen
plts fV, fVIII Ca2 |
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why can a pt develop tachyphylaxis with ephedrine use?
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ephedrine -> incr release of catechol stores -> can deplete
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effects of B agonist on CV system x3
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incr HR
incr contractility incr RAAS |
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why esmolol v propranolol in...
1. OR generally? 2. asthmatics? |
1. esmolol - fast on, fast off
2. asthmatics esmolol - B1 selective propranolol - B1/B2 (->) bronchospasm in asthmatics |
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newborns:
a. why do they get cold faster? b. mechanisms for heating? |
a. larger SA/weight ratio than adults
b. thermogenesis (brown fat), moving extrems, crying |
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why are infants more rapidly induced via facemask than adults?
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higher VA/FRC ratio (= greater minute ventilation per unit of FRC) -> faster increase in FA/Fi
also, reduced solubility in tissue/blood -> vapor equilibrates more rapidly |
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what is caudal anesthesia?
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like a single shot spinal anesthetic, but needle introduced thru sacral hiatus
provides INFRAUMBILICAL anesthesia |
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caudal anesthesia: why easier in kids?
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techniically easier to locate sacral hiatus in adults
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why is O2 sat maintained around 90% for preemies?
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decr incidence of retinopathy of prematurity
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what equipment is necessary for prolonged intubation of an infant?
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smaller OETT (? uncuffed) to avoid subglottic stenosis
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2 reasons why kids desat more rapidly than adults?
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-higher VO2 (6mL/kg/min)
-smaller O2 reserves (decr TLC/kg) |
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MH
a. occurs in response to ... b. mech c. results |
a. SUX, vapor
b. genetic variant? -> (drug) -> ↑↑↑↑ skeletal muscle metabolism -> ↑↑↑↑ VO2 -> body can't meet demand or clear waste products c. tachycardia, hypercarbia, acidosis, hyperthermia (late) |
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what is the aldrete score?
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criteria to determine release from PACU
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components of aldrete score x5
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activity (to cmd)
breathing circulation (SBP) consciousness O2 sat like APGAR, each category gets 0-2 points for certain responses... require 9/10 to be discharged |
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2x most common causes of post-op hypoxemia?
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atelectasis or hypoventilation
NB: -incr PCO2 can cause decr PAO2 (via alveolar gas eqn) -linear vent response to PCO2 blunted by vapor, drugs |
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most common cause of postop hypoTN?
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hypovolemia
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most common cause of postop HTN?
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pain
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most common cause of postop depressed consciousness?
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residual effect of vapor, opioids, sedative-hypnotics
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adverse fx of hypothermia postop (x4)
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-unpleasant shivering
-incr VO2 -coagulopathy (decr plt fnc and coag factor act) -decr drug metabolism NB: shivering may not be entirely mediated by cold; spinal cord recovers from anesthesia before brain |
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review O2 delivery devices (notebook p36)
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see notebook
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nerve(s) most likely to be injured in lateral position
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brachial plexus
peroneal nerve |
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nerve(s) most likely to be injured in seated position
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sciatic nerve
prevent with hip/knee flexion |
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nerve at greatest risk in lithotomy position
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peroneal nerve
(compression against stirrups) |
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nerve(s) most likely to be injured in any surgery
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ulnar nerve
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injuries most likely due to facemask application?
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1. study guide
-eyebrow loss -nasal bridge necrosis -bradycardia (2/2 oculocardiac reflex) -facial nerve injury could not corroborate any of the above in miller basics, miller, or barash. most common injury triply cited is corneal abrasion. |
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areas of skin x5 most likely to be affected by poor padding
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-occiput
-corner of nose/mouth (2/2 tubes) -medial epicondyles -inner knee -heel |
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what factors affect the...
a. dist/spread of epidural/spinal? (x3) b. duration of epidural/spinal? (x2) |
a.
baricity curvature of spine positioning in first few mins after injection b. vasoconstrictors LA agent |
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at what spinal level of block is decr BP expected to occur?
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T12
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at what spinal level of block is bradycardia expected to occur?
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T2?
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at what spinal level block might dyspnea begin?
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C6
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why is dyspnea almost guaranteed with C2 block?
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paralysis of phrenic nerve
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the patient who has hypoTN from neuraxial block is most likely to have ↓SBP > ↓DBP -- why?
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arterial vasodilation
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how should you size the BP cuff relative to pt's arm?
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two methods:
BP cuff width = 40% of circum of pt's arm BP cuff covers 2/3 of exposed space on limb b/t joints |
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how does the size of BP cuff affect reading if it is...
a. too small? b. too large? |
a. TOO SMALL -> overestimation (BP appears higher than it is)
b. TOO LARGE -> underestimation (BP appears lower than it is) |
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EKG: best lead for arryhthmia?
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Lead II
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Best EKG leads for ischemia
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V5 alone - sens 75%
V4/V5 - 90% II/V4/V5 - 96% |
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9x situations that alter accuracy of pulse oximetry
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-pt movement
-low flow states -ambient light -metallic nail polish -Hgb abnormality (carbodyxy-, met-) -R shifted O2-Hgb dissociation curve -dyes (methylene blue, others) -electrical activity -edema -obesity |
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DDX: sudden decr in ETCO2 (x4)
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-embolus
-hypoventilation -hypoTN/↓CO -disconnected vent |
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DDX: sudden incr in ETCO2?
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-incr VO2 (ie, hypermetabolic states: MH, thyroid storm)
-decr VA (hypoventilation) -incr FiCO2 -LSC surgery with CO2 insufflation |
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indications for A-line x2
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-continuous BP monitoring needed
-multiple lab draws |
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complications of Aline x5
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bleeding, infection, distal ischemia, thrombosis, nerve injury
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indications for central line (CVC) x4
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-blood volume estimation needed
-large vein access -difficult IV access -hyperalimentation |
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complications of central line x9
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-arterial puncture
-a/v/n injury -ptx -bleeding -infection -thoracic duct injury -dysrhythmia -atrial injury -wire loss -wire knotting |
