Mechanical Ventilation Handout - allenho

Mechanical Ventilation Handout - allenho -...

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Principles of Mechanical  Ventilation David M. Lieberman, MD Allen S. Ho, MD Surgery ICU Service Stanford University Medical Center September 25, 2006 The Basics
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Origins of mechanical ventilation Origins of mechanical ventilation Negative-pressure ventilators  (“iron lungs”) Non-invasive ventilation first used  in Boston Children’s Hospital in  1928 Used extensively during polio  outbreaks in 1940s – 1950s Positive-pressure ventilators Invasive ventilation first used at  Massachusetts General Hospital in  1955 Now the modern standard of  mechanical ventilation The era of intensive care medicine began with positive-pressure ventilation The iron lung created negative pressure in abdomen  as well as the chest, decreasing cardiac output. Iron lung polio ward at Rancho Los Amigos Hospital in  1953.
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Outline Outline Theory Ventilation vs. Oxygenation Pressure Cycling vs. Volume Cycling Modes Ventilator Settings Indications to intubate Indications to extubate Management algorithim FAQs
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Principles (1): Ventilation Principles (1): Ventilation The goal of ventilation is to facilitate CO release and maintain normal P a CO 2 Minute ventilation (V E ) Total amount of gas exhaled/min. V E  = (RR) x (T V ) V E  comprised of 2 factors V A  = alveolar ventilation V D  = dead space ventilation V D /V T  = 0.33 V E  regulated  by  brain  stem,  responding to pH and P a CO 2 Ventilation in context of ICU Increased CO 2  production fever, sepsis, injury, overfeeding Increased V D atelectasis,   lung  injury,  ARDS,  pulmonary embolism V/Q  Matching.    Zone  1  demonstrates  dead-space  ventilation   (ventilation without perfusion).   Zone 2  demonstrates normal perfusion.   Zone 3  demonstrates  shunting  (perfusion without ventilation).
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Principles (2): Oxygenation Principles (2): Oxygenation The primary goal of oxygenation is to maximize O 2  delivery to blood (P a O 2 ) Alveolar-arterial O 2  gradient  (P A O – P a O 2 ) Equilibrium between oxygen in  blood and oxygen in alveoli A-a gradient measures efficiency of  oxygenation P a O 2  partially depends on   ventilation but more on V/Q  matching Oxygenation in context of ICU V/Q mismatching Patient position (supine) Airway pressure, pulmonary  parenchymal disease, small- airway disease Adjustments:  FiO 2  and PEEP V/Q  Matching.    Zone  1  demonstrates  dead-space  ventilation   (ventilation without perfusion).   Zone 2  demonstrates normal perfusion.   Zone 3  demonstrates  shunting  (perfusion without ventilation).
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Pressure ventilation vs. volume ventilation Pressure ventilation vs. volume ventilation
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This note was uploaded on 12/21/2011 for the course STEP 1 taught by Professor Dr.aslam during the Fall '11 term at Montgomery College.

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Mechanical Ventilation Handout - allenho -...

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