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Anatomy and Physiology Pearls

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By Dan Zauski 4 min read

Airway Innervation

airway airway

Alpha 1 Antitrypsin Deficiency

  • Made in liver and stops enzyme alveolar elastase
  • Deficiency causes destruction of pulmonary connective tissue resulting in panlobular emphysema

Anticholinergic / Cholinergic Syndromes

Anticholinergic

  • Antimuscarinic use (scopolamine)
  • Minimal temp inc, dry mouth, delirium, dry skin, midriasis
  • Tx: Physostigmine (only one that can cross BBB)

Cholinergic

  • Organophosphates, nerve agents, nicotine poisoning, cholinesterase inhibitor OD (myasthenia pts)
  • Tx: Antimuscarininc drugs such as atropine, if resp compromise intubate and wait for acetylcholine level to come down (no way to reverse nicotinic receptor issue)

Autonomic Hyperreflexia

  • Stimulation of sympathetic nervous system below level of spinal cord injury (bladder catheter etc)
  • Causes HTN emergency due to lack of inhibitory reflexes below injury and bradycardia
  • Tx: Deepen anesthetic or use rapid acting vasodilators
  • GA and spinal best anesthetic choice

Bicarbonate

bicarb

  • Hyperosmolar, hypervolemia, hypernatremia, together cause inc ICP
  • Left shift from bicarb on oxyhgb curve lasts up to 8 hrs dec PaO2
  • Dec ionized calcium
    • Need to replace calcium with bicarb admin

  • Administer Bicarbonate only in nongap acidosis such as renal tube acidosis, hyperk, diarrhea, enterocutaneous fistula. Consider bicarb in lactic acidosis if ph< 7.1 Minimal research to back this up. Rta type 1 is related to Ehler danlos, uti, sickle. RTA type 2 with rickets. RTA type 4 seen with urinary obstruction, immunosuppressants, kidney rejection. Also seen with many meds like diuretics and ace. Symptoms are high potassium and low bicarb.

  • Probably not beneficial in cardiac surgery
  • Bicarb is not shown to dec PVR, improve response to pressors, or inc CO

Cerebral Blood Flow

cerebral blood flow

CO2 Curve

co2 curve

Bohr Effect

  • CO2 and decreased pH cause erythrocytes to release O2

Haldane Effect

  • O2 causes the erythrocyte to release CO2

Coagulation Cascade

coagulation cascade

Electrolye Review

Calcium

  • Parathyroid Hormone
    • Inc Ca release from bones (osteoclast)
    • Inc renal reabsorption
    • Inc Vit D3 activation (VitD comes from skin and is made into D3 in liver and activated in kidney)
    • Inc Ca reabsorption in intestines
  • Calcitonin
    • Dec Ca release from bones
  • Bisphosphonates
    • Treatment for hypercalcemia
  • Secondary hyperPTH
    • Caused by decreased kidney function and or decreased Vit D3

Potassium

  • Shift into Cell:
    • Insulin (Na/K/ATPase)
    • Aldosterone (Conn syndrome causes hypokalemia)
    • Beta Agonist
    • Alkalosis
  • Shift Out
    • Dec Insulin (DM)
    • Addisons (Dec aldosterone)
    • Beta Blockade
    • Acidosis (Dec fx of Na/K/ATPase)
    • Exercise (cell lysis)

Heart Failure Review

Diastolic

  • Preserved EF
  • Pressure work
  • Hypertrophy
  • Want nl preload, nsr, and dec afterload to help dec tissue remodel
  • Give beta and calcium channel blockers
  • Norepi for pressor

Systolic

  • Dec EF
  • Volume work
  • Dilated
  • Want nl preload, nsr, and dec afterload due to weak ventricle
  • Give inotropes and vasodilators

High Altitude Physiology Review

  • Cerebral edema: hypoxia and vascular dilation

  • Pulmonary edema: hypoxia causes vasoconstriction which inc capillary pressure: right heart failure eventually

  • Tx with Acetazolamide to acidify the blood and inc ventilation (Carbonic anhydrase inhibitor)
  • Nifedipine to stop vasoconstriction in lungs

Neuroleptic Malignant Syndrome

  • Dopamine Antagonist (1-3 days)
  • Very inc temp, drooling, palor, coma, dec reflex, unstable autonomic nervous system (inc/dec BP/HR)
  • Tx: Stop dopamine antagonist, give dopamine agonist (Bromocriptine, amantadine), IV fluid, cooling, benzos for agitation, Dantrolene for muscle relaxation

Oxyhemoglobin Dissociation Curve

oxyheme

Pain

Pain Pathway

  1. Tranduction: injury causes activation of fast A-Delta and slow C fibers. Substance P is released
    • Target Drugs: Local Anesthetic Cream, NSAIDs, Opioids
  2. Transmission: Signals travel towards the brain via the spinothalamic tract
    • Target Drugs: Local Anesthetic blockade
  3. Modulation: Within the substantia gelatinosa of the spinal cord
    1. Inhibition via the descending inhibitory pathway: 5HT and NE, effect inc with antidepressants
    2. Augmentation via central sensitization and wind up: Blocked by ketamine and precedex
    3. Secondary Hyperalgesia: Inc substance P, triple response of dilation, erythema, wheal
    4. Primary Hyperalgesia: PGE2 stimulates free nerve endings
      1. NSAIDs and Steroids block PGE2
      2. Tylenol may antagonise cannabinoid receptors or a possible COX 3 - Target Drugs: NMDA anatagonists, Neruaxial Opioids, Alpha-2 Agonists, SNRIs
  4. Perception
    • Target Drugs: General Anesthetics, Opioids, Alpha-2 Agonists

pain

Opiates

  • Mu1: classic opiate effects
  • Mu2 dependence, spinal analgesia
  • Mu3 Immunosuppression
  • Kappa: Dysphoria, hallucination, Antishiver
  • Delta: Itching

Renal Review

AKI

  1. Prerenal :
    1. Dec blood flow/oxygen d/t dec volume
    2. Burns
    3. Vomit
    4. Sepsis
    5. Renal artery stenosis/thrombosis
  2. Intrarenal :
    1. Glomerulonephritis
    2. HTN
    3. Pylo
    4. Acute Tubular Necrosis (ischemic, or medication/toxin)
  3. Post Renal
    1. Stones/obstruction

CKD

List of signs/symptoms:

Uremia, azotemia (inc nitrogen), edema, ascites, anemia (d/t dec erythropoietin), osteomalacia (dec vit D activation and inc phosphate retention)

Nephrotic Syndrome

  • Loss of proteins across kidney tubules: from chronic glomerulonephritis, amyloidosis
  • Causes dec osmotic pressure and profound edema

Respiratory Tests/Spirometry

Closing Volume

  • Volume at which dynamic airway compression occurs
  • Inc with age, obstructive disease, obesity, preggo

Closing Capacity

  • Closing Volume + Residual Volume
  • Normally in spontaneously ventilating pts FRC > CC so airways do not collapse
  • If FRC < CC airways collapse during normal tidal breathing leading to dec O2 sat, inc shunt
    • Tx with peep

Residual Volume

  • Not measured in spirometry
  • Increased in obstructive disease
  • Decreased in restrictive disease

Total Lung Capacity

  • Increased or normal in obstructive disease

Interpreting PFTs

pft

Serotonin Syndrome

Signs/Symptoms

  • Inc temp, inc reflex, drooling, coma, agitated, sweating

Causes

  • SSRI/SNRI especially with MAOI
  • Inc risk with: linezolid, methylene blue, lithium, fentanyl, stimulants like amphetamine, cipro, Erythromycin

Treatment

  • Cooling, IV fluids, paralysis/vent if temp uncontrolled 41C<, cyproheptadine, benzos

Thyroid Review

  • TRH – TSH – T4 – T3 (activated T4-T3 in cells)
    • Levothyroxine (T4)
  • Hyperthyroid Tx: Methimazole, Propylthiouracil (stops T4-T3), No amiodarone due Iodine
  • Thyroid Storm: Propranolol is best beta blocker (stops T4-T3) and PTU
Anesthesia, Anatomy
anatomy physiology
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