Mechanical Ventilation Flashcards
Oxygen delivery equation
DO2= cardiac output x arterial O2 Content
Reasons for oxygen delivery failure
hypotension, acidosis, coagulopathy
oxygen use equation
VO2=Cardiac output x O2a-O2v
The normal oxygen extraction ratio is
about 25%
heart has very high demand
The anesthesia goal of oxygen therapy is
to maintain oxygenation and ventilation
The oxygen therapy goal is
prevention and correction of hypoxemia and tissue hypoxia
Surgical patients have an
increased risk of hypoxemia & hypoxia
Hypoxemia is
deficiency of O2 in blood
Hypoxia is
O2 delivery to tissues not sufficient to meet metabolic demand
Types of hypoxia include
hypoxic, circulatory, hemic, demand, and histotoxic
Hypoxia signs and symptoms include
vasodilation, tachycardia, tachypnea, cyanosis, confusion, and lactic acidosis
Improving oxygenation in mechanically ventilated patients includes
treatment tailored to cause
utilizing increase VE, increased cardiac output, increased O2 carrying capacity, optimize V/Q relationship, decrease O2 consumption, increase FiO2
The nasal cannula (flow rates)
flow rates 1-6 L/min
FiO2 increases about 4% per L/min
Simple face masks (FiO2)
minimum 6L flow required to prevent rebreathing
FiO2 40-60%
Face masks with reservoirs
FiO2 60-100%
Venturi masks
have more precise FiO2 of 24-50%
have to set flow rate
Based off of Bernoulli’s theory
Oxygen toxicity occurs from
high FiO2 over long periods which can be harmful to lung tissue and cause
decreased ciliary movement, alveolar epithelial damage, and interstitial fibrosis
Oxygen toxicity is dependent upon
FiO2, duration, patient susceptibility
Safe levels of oxygen to prevent oxygen toxicity is
100% O2 for up to 10-20 hours
Oxygen toxicity occurs from
50-60% O2 for more than 24-72 hours
Absorption atelectasis occurs when
nitrogen is replaced by oxygen
under-ventilated alveoli have decreased volume- due to greater uptake of oxygen
increases pulmonary shunting
Induced hypoventilation occurs due to
Chronic CO2 retainers rely on hypoxic drive
peripheral chemoreceptors are triggered by hypoxemia
Increased O2 can lead to hypoventilation
Fire hazards can occur because
O2 supports combustion
use extreme caution with head and neck cases
Retinopathy occurs
with O2 therapy in neonates; it can lead to vascular proliferation, fibrosis, retinal detachment, and blindness