Preop Evaluation, Risk Assessment and Anesthesia – Flashcards

Unlock all answers in this set

Unlock answers
question
How common are problems with anesthesia?
answer
Although all types of anesthesia involve some risk, major side effects and complications from anesthesia are uncommon. (Mortality<0.3%)
question
Preoperative Evaluation For Anesthetic Risk is
answer
Difficult to assess precisely.
question
Perioperative complications
answer
are often multifactorial: Concurrent Disease Complexity of the Procedure Drug Interactions Adverse Effects of Anesthesia
question
Preoperative Evaluation
answer
Preoperative H & P usually done by primary care provider or surgeon. Anesthesia team often meets patient for first time 1 hour or less prior to surgery.
question
purpose of preoperative evaluation
answer
"The purpose of a preoperative evaluation is *not* to 'clear' patients for elective surgery, but rather to evaluate and, if necessary, implement measures to prepare higher risk patients for surgery."
question
goal of preoperative evaluation
answer
understand the risk associated with the particular type of surgery planned and relate this risk to the patient's underlying acute and chronic medical problems."
question
Physical Classification System
answer
see Anesthesia powpt slides 6 & 7 one question on test
question
Preoperative Evaluation Must review...
answer
Previous experience with anesthesia HPI Concurrent Diseases Exercise Tolerance Social History (Drugs, Alcohol, Tobacco) Family History
question
Previous experience with anesthesia
answer
Allergies Delayed awakening Prolonged paralysis from neuromuscular blockers Jaundice
question
concurrent diseases
answer
DM Coagulopathy Hepatic or Renal Dysfunction Cardiorespiratory Dysfunction
question
Smoking Cessation
answer
Cessation 2 months prior to surgery decreases the risk for postoperative pulmonary complications. Cessation of smoking within 2 weeks of surgery may paradoxically increase the risk of pulmonary complications.
question
Preoperative Evaluation Exam
answer
Focus on CV system, lungs, and upper airway Airways, head and neck - factors which may interfere with intubation Peripheral venous sites
question
Focus on CV system, lungs, and upper airway
answer
HR BP - supine and standing Auscultation - murmurs, carotid bruits, abnormal resp
question
Airways, head and neck - factors which may interfere with intubation
answer
Fat or short neck - Visibility of uvula and soft palate? Limited TMJ mobility
question
Peripheral venous sites
answer
particularly if regional block
question
Obstructive Sleep Apnea (OSA)
answer
Characterized by repeated complete or partial collapse of the pharyngeal airway during sleep, causing cessation of airflow (apnea) or shallow breathing (hypopnea). Affects 4% and 2% of middle-aged men and women, respectively (more than asthma).
question
OSA and surgery/anesthesia
answer
Shown to significantly increase postoperative complication rates, increase the need for intensive care intervention, and prolong hospital stays.
question
Preoperative Evaluation Obstructive Sleep Apnea
answer
Screening (Standard on all Mayo Pre-op) - Scored Polysomnography recommended for high risk patients.
question
Screening (Standard on all Mayo Pre-op) - Scored
answer
Neck Circumference Hypertension Do you Snore? Do you gasp, choke, snort when sleeping?
question
OSA precautions during and after surgery
answer
Close attention to airway management is required and regional anesthesia should be used whenever possible. Postoperative pain management should minimize the use of opioids and other sedatives. Pulse oximetry - Postoperative CPAP therapy.
question
Preoperative Evaluation Concurrent Drug Therapy
answer
increased or decreased Anesthestic requirements increased CV response to sympathomimetics and anesthetics decreased Peripheral sympathetic activity, depressant reaction to anesthetics may be augmented
question
increased or decreased Anesthestic requirements
answer
Smoking Alcohol
question
increased CV response to sympathomimetics and anesthetics
answer
TCA's
question
decreased Peripheral sympathetic activity, depressant reaction to anesthetics may be augmented
answer
Antihypertensives Antiarrhythmics.
question
Preoperative Evaluation Laboratory Tests determined by
answer
H and P (Results may alter management)
question
Preoperative Evaluation Laboratory Tests for healthy people
answer
Healthy ♂ < 40 may require none. ♀ only hgb.
question
Preoperative Evaluation Laboratory Tests
answer
PT, PTT - anticoagulants or hx suggests coagulopathy Hgb/CBC - concerns regarding blood loss ECG - ♂ >40 or ♀ >50 + Interm to High Risk Surg CXR - Symptoms or exam suggest lung or CV disease.
question
Preoperative Cardiac Assessment
answer
Noninvasive stress testing rarely helpful. Most patients - optimal medical management as good as surgical revascularization. Functional capacity is important in assessing risk.
question
Reducing The Risk of Perioperative Cardiac Events
answer
Beta Blockers Alpha-2 Blocker Nitrates Statins Aspirin
question
Beta Blockers
answer
Proven benefit in patients with risk factors, abnormal cardiac testing, or known disease.
question
beta blocker selection, use
answer
Use cardioselective agents (atenolol, metoprolol, etc.) Best to begin 2-4 weeks before surgery. Titrate to target HR to 55-65 as BP tolerates (>100 systolic).
question
Alpha-2 Blocker
answer
Blocker (Clonidine) if don't tolerate BB. (proven)
question
Nitrates
answer
No proven benefit. May cause hypotension
question
Statins
answer
In addition to lipid lowering, statins reduce vascular inflammation and stabilize plaque. Evidence shows that they reduce cardiovascular risk in patients undergoing vascular procedures. Benefit regardless of cardiac risk factors.
question
statin use
answer
Ideally started a couple weeks before, but still beneficial right before.
question
Aspirin
answer
Discontinuation in 2° prevention CAD - 3x increases events Discontinuation coronary stents - 90x increases events Increases surgical bleeding ~20% In most cases, it should be continued; must weigh the risks of cessation vs bleeding risks.
question
Antithrombotic or Anticoagulant Therapy
answer
Management depends on original indication for therapy, comorbid conditions, and bleeding risk of procedure.
question
Antithrombotic or Anticoagulant Therapy - Common strategies: low bleeding risk procedure
answer
Warfarin - cont. adjust INR to low end of range Continue antiplatelet agents
question
Antithrombotic or Anticoagulant Therapy - common strategies high bleeding risk/low thrombotic risk
answer
Discontinue warfarin 3-5 days before. Restart immediately post procedure (stable surgically). Consider IV heparin 24-48 hours after surgery.
question
Antithrombotic or Anticoagulant Therapy - High bleeding-risk procedure/high thrombotic risk
answer
Discontinue warfarin 3-5 days before. IV heparin or SQ LMWH when INR subtherapeutic. Surgery when INR<1.5 (Stop heparin 6 hrs or LMWH 24 hours before the procedure) Restart heparin and warfarin as soon as safe from surgical standpoint, stop heparin when INR therapeutic.
question
Perioperative Management of Diabetic Medications
answer
Oral agents held the morning of surgery Short acting insulin held the morning of surgery These are resumed when diet is resumed ½ to 2/3 of long acting insulin given on day of surgery Many patients will require insulin drip during major surgeries.
question
Presumed HPA Suppression
answer
20 mg of prednisone a day for > 3 weeks. Evening/bedtime dose of prednisone for more than a few weeks. Cushingoid appearance. Such patients do not need testing to evaluate their HPA function, but should be treated like any patient with secondary adrenal insufficiency
question
patient with secondary adrenal insufficiency
answer
wearing of a medical alert bracelet or necklace, carrying an emergency medical information card, and, arguably, a preloaded 1-mL syringe containing 4 mg dexamethasone phosphate to inject in emergencies.
question
4 METS
answer
slide 22
question
cardiac risk assessment
answer
slide 21
question
Intermediate/Uncertain Risk HPA Suppression
answer
10 to 20 mg of prednisone per day for > 3 weeks Less than 10 mg of prednisone or its equivalent per day, providing that it is not taken as a single bedtime dose for more than a few weeks
question
If withdrawal from glucocorticoids is otherwise indicated
answer
gradual reduction in dose is appropriate for these patients with an intermediate or uncertain risk of HPA suppression. Such patients do not need to be tested for HPA functional reserve unless abrupt discontinuation is being considered or the patient is facing an acute stress such as surgery
question
HPA Suppression Unlikely
answer
A patient who has received any dose of glucocorticoid for less than three weeks. Patients treated with alternate-day glucocorticoid therapy.
question
Corticosteroid coverage for surgery in patients taking exogenous corticosteroids - Minor procedures or surgery under local anesthesia (inguinal hernia repair)
answer
Usual morning steroid dose. No extra supplementation is necessary.
question
Corticosteroid coverage for surgery in patients taking exogenous corticosteroids - Moderate surgical stress (total joint replacement)
answer
Usual morning steroid dose. Give 50 mg hydrocortisone intravenously just before the procedure and 25 mg of hydrocortisone every 8 hours for 24 hours. Resume usual dose thereafter.
question
Corticosteroid coverage for surgery in patients taking exogenous corticosteroids - Major surgical stress (cardiac bypass)
answer
Usual am steroid dose. Give 100mg of intravenous hydrocortisone before induction of anesthesia, and 50mg every 8 hours for 24 hours. Taper dose by half per day to maintenance level.
question
Local anesthetics
answer
Block the conduction of nerve impulses in the peripheral nerves or spinal cord. Anesthetize a particular part or region of the body
question
local anesthetic uses
answer
Surgery on the skin and subcutaneous tissues, ears, eyes, joints, or pelvis.
question
Neuroaxial Anesthesia
answer
Spinal Anesthesia Epidural anesthesia Both carry small risk of epidural hematoma (can't be on anticoagulants or antithrombotics.)
question
Spinal Anesthesia
answer
Local anesthetics or opioids are injected into the subarachnoid space using a needle or catheter.
question
Epidural anesthesia
answer
Local anesthetics or opioids are injected into the epidural space using a needle or catheter.
question
General anesthetics
answer
Block cortical neuronal activity underlying consciousness and all sensation. Used to prevent consciousness during major surgical procedures. Produce loss of consciousness and amnesia and thereby prevent the anesthetized patient from recalling the surgical procedure.
question
Local Anesthetics MOA
answer
Reversible inhibition of action potential conduction by binding to the sodium channel and decreasing the nerve membrane permeability to sodium. Binds to the cytoplasmic side of the sodium channel protein. Prolongs the inactivation state of the sodium channel. Action potentials cannot propagate along the neuronal fiber and sensory input is lost
question
all local anesthetics are
answer
weak bases
question
only form of local anesthetic that can penetrate neuronal membranes to reach binding sites on the internal surface of sodium channels.
answer
noninonized
question
ionization and local anesthesia - what's the issue?
answer
Inflammation and acidosis decrease the pH of tissues, thereby increasing the ionization of local anesthetics. For this reason, local anesthetics are less effective in the presence of these conditions, requiring larger doses.
question
local anesthetic with long duration of action
answer
Etidocaine
question
lidocaine
answer
local anesthetic short duration of action
question
lidocaine uses
answer
Epidural, infiltration, nerve block, and spinal anesthesia. Dermal, laryngeal, and oral.
question
General Anesthetics - advantages (in ideal circumstances)
answer
Asleep Amnesia Absence of movement Analgesia Does not suppress protective reflexes, respiratory, or cardiovascular function. Rapid onset; rapid and safe emergence. No allergies or side effects. Cheap and easy to administer.
question
General Anesthetics - Induction
answer
stages I - IV
question
stage I
answer
neurons in the spinal cord are prevented from firing and analgesia and conscious sedation occurs.
question
stage II
answer
inhibition of firing in small inhibitory neurons can cause paradoxical excitation, although with modern balanced anesthesia this stage is often not observed.
question
stage III*
answer
is the goal of surgical anesthesia with suppression of the reticular-activating system, loss of consciousness, and inhibition of spinal reflexes (muscle relaxation)*
question
stage IV
answer
can lead to cardiovascular collapse, is noted by depression of the respiratory and vasomotor nuclei in the brainstem. (AVOID)
question
Inhalational Anesthetics
answer
Diethyl ether
question
Diethyl ether
answer
no longer used in developed countries, because it has a slow rate of induction, causes considerable postoperative nausea and vomiting, and is highly flammable
question
Cyclopropane
answer
also abandoned, because of its explosive nature and its tendency to cause cardiac arrhythmias. (Hmmm, doesn't sound explosive.)
question
potency of inhalational anesthetics
answer
expressed in terms of the inspired concentration of the anesthetic required to produce anesthesia in half of the subjects. This is called the minimal alveolar concentration (MAC).
question
minimal alveolar concentration (MAC)
answer
Defined as no movement with painful stimulation (incision).
question
Nitrous Oxide
answer
Gaseous anesthetic - Colorless, odorless, unflammable. Cannot produce surgical anesthesia by itself. Reduces the MAC for halogenated anesthetics in combo.
question
nitric oxide pharmicokinetics
answer
Extremely fast absorption and elimination Rapid induction and recovery from anesthesia
question
nitric oxide uses
answer
Has good analgesic properties. For procedures that do not require unconsciousness.
question
nitric oxide contraindications
answer
head injury, preexisting increased intracranial pressure, tumor. N2O can raise intracranial pressure.
question
Halothane
answer
Most potent volatile anesthetic Very soluble in blood and adipose Prolonged emergence
question
complications with halothane
answer
Cardiac depressant --Dose dependant --Sensitizes myocardium to epinephrine Halothane Hepatitis --1/10,000 cases (~50% fatal) --Immune mediated reaction to metabolite Malignant Hyperthermia
question
Malignant Hyperthermia
answer
Sustained muscle contractions. Dramatic increase in oxygen consumption (hypoxemia). Increased body temperature.
question
causes of malignant hyperthermia
answer
Halogenated anesthetics (halothane in particular), can precipitate malignant hyperthermia in genetically susceptible patients. Depolarizing neuromuscular blocking agents (succinylcholine) can also trigger this reaction.
question
Malignant Hyperthermia treatment
answer
Rapid cooling and administration of the skeletal muscle relaxant dantrolene (IV).
question
associated with the highest incidence.of malignant hyperthermia
answer
Malignant hyperthermia occurs in 1/15,000 (peds) to 1/50,000 (adults) cases. The combined use of halothane and succinylcholine is associated with the highest incidence.
question
inhaled anesthetic with no effect on CV system
answer
Sevoflurane
question
inhaled anesthetic with slow onset
answer
Halothane
question
inhaled anesthetic with more (20%) metabolized
answer
halothane
question
inhaled anesthetic that sensitizes the heart to catecholamines
answer
halothane
question
inhaled anesthetics that are hepatotoxic
answer
halothane Enflurane
question
inhaled anesthetic which is NOT metabolized at all
answer
nitric oxide
question
inhaled anesthetics?
answer
Nitrous oxide Desflurane Isoflurane Sevoflurane
question
IV Anesthetics
answer
Ultrashort-acting barbiturates (thiopental) Propofol Dissociative anesthetics (Ketamine) High-potency opioid anesthetics (fentanyl, alfentanil) Midazolam or lorazepam Etomidate
question
Ultrashort-acting barbiturates (thiopental)
answer
Poor analgesia Rapid onset, short duration Primary uses Induction of anesthesia Procedures of short duration
question
Propofol
answer
Preferred for 1-day surgical procedures because of rapid recovery. May cause hypotension
question
Dissociative anesthetics (Ketamine)
answer
During induction, patients feel dissociated from the environment (trancelike states).
question
Dissociative anesthetics (Ketamine) uses
answer
Allows patients, particularly children, to be awake and respond to commands yet endure painful stimuli Example: changing painful burn dressings
question
Dissociative anesthetics (Ketamine) adverse effects
answer
Increased heart rate, cardiac output, and arterial blood pressure Postoperative psychotic phenomena (hallucinations) Rarely used in adults because of this effect
question
High-potency opioid anesthetics (fentanyl, alfentanil)
answer
Used in cardiothoracic surgery to avoid the cardiac effects of many inhalation agents
question
Midazolam or lorazepam
answer
Used for procedures that require consciousness
question
Etomidate
answer
A short-acting Minimal cardiovascular effects, no histamine release Useful for patients with compromised cardiopulmonary function
question
parenteral anesthetics that are analgesic
answer
Fentanyl Ketamine
question
parenteral anesthetic causing amnesia
answer
Midazolam (Versed)
question
parenteral anesthetics causing respiratory depression
answer
Fentanyl Propofol Thiopental
question
parenteral anesthetic that causes post-anesthetic delirium and hallucinations
answer
Ketamine
question
Balanced anesthesia
answer
A combination of various anesthetic agents is used, each in small doses, to reduce the chance of significant side effects. This is now common practice.
question
patient experience with different forms of anesthesia
answer
IV anesthesia - Induction is rapid, smoother, and more pleasant for the patient. Inhalational anesthesia - Slower onset, vapors that may be unpleasant, and facemask delivery system. Hypnotic and opioid drugs are often administered IV to assist induction and anesthesia management.
question
To enhance beneficial therapeutic effects and reduce unwanted side effects,
answer
Balanced Anesthesia: Inhaled anesthetics IV anesthetics Narcotics Sedatives
question
opioids to sedate, decrease tension/anxiety and provide analgesia (NBD)
answer
morphine meperidine (demerol) fentanyl
question
barbiturates to sedate, decrease apprehension, with rapid induction (NBD)
answer
pentobarbitol secobarbitol thiopental
question
benzodiazapines to sedate, decrease apprehension, with rapid induction (NBD)
answer
diazepam (valium) lorazepam (ativan)
question
Phenothiazines effects and drugs (NBD)
answer
anti-emetic prochlorperazine promethazine
question
anticholinergics effects and drugs (NBD)
answer
Inhibition of secretions, vomiting, and laryngospasms atropine scopolamine glycopyrrolate
question
antiemetics for postoperative vomiting (NBD)
answer
droperidol hydroxyzine ondansetron
question
Polypharmacology
answer
may have 25 Different Medications in 1-3 hours!!!
question
The Anesthesia Machine
answer
oxygen Breathing circuit Ventilator Carbon dioxide absorber Suction Anesthetic agents Monitoring -airway -Breathing -circulation -drug
Get an explanation on any task
Get unstuck with the help of our AI assistant in seconds
New