B4.054 Respiratory Failure

Question 1

definition of resp failure

Answer 1

patient loses ability to ventilate adequately or to provide sufficient oxygen to the blood and systemic organs

Question 2

significance of resp failure

Answer 2

one of most common reasons for ICU admission

>75% of patients require mechanical ventilation during their stay

Question 3

immediate interventions for respiratory failure

Answer 3

arterial blood gases drawn on room air
O2 is started/ nasal cannula
peripheral IV is started
CBC and chemistries drawn

Question 4

what drug reverses opiod overdoses

Answer 4

naloxone

Question 5

Type 1 resp failure

Answer 5

hypoxic

Question 6

what is a likely cause of hypoxic resp failure

Answer 6

low V/Q ratio (shunt)
intrapulmonary
poor oxygenation of blood through pulmonary capillaries

Question 7

what are possible sources of shunts?

Answer 7

blood
pus- pneumonia
water- CHF
atelectasis

Question 8

does shunting dramatically influence PaCO2?

Answer 8

no, much greater effect on PaO2

body can blow off extra CO2 pretty easily and maintain near normal

Question 9

does giving more O2 help PaO2 when a shunt is present?

Answer 9

no
good alveoli cant compensate for the bad due to the shape of oxygen binding curve
cant increase O2 content much

Question 10

type 2 resp failure

Answer 10

hypercapnic

Question 11

what is a likely cause of hypercapnic resp failure?

Answer 11

respiratory pump failure

always accompanied by resp acidosis when acute

Question 12

ratio of physiologic dead space to tidal volume

Answer 12

1/3

Question 13

2 basic mechanism of hypercapnic resp failure

Answer 13

1. decreased capacity (extrapulmonary) > decreased minute ventilation
2. increased load (pulmonary parenchymal or airway disorders) > increased dead space

Question 14

sources of decreased capacity

Answer 14

decreased central respiratory drive
neuromuscular disorders
thoracic cage disorders

Question 15

sources of increased load

Answer 15

increased resistive load
elastic load
increased VE demand

Question 16

is ventilation is halved

Answer 16

PaCO2 doubles

Question 17

if PaCO2 raises 10 mmHg

Answer 17

pH decreases 0.08 points

Question 18

alveolar ventilation equation

Answer 18

VA=(VT-VD)*RR

Question 19

type 3 resp failure

Answer 19

occurs in perioperative period when factors that reduce functional residual capacity combine with causes of increased closing volume to produce progressive atelectasis

Question 20

type 4 resp failure

Answer 20

ensues when circulation fails and resolves when shock is corrected

Question 21

why is the alveolar-arterial (A-a) gradient useful

Answer 21

distinguishes hypercapnic respiratory failure due to global respiratory failure from respiratory failure due to abnormal gas exchange from intrinsic lung disease

Question 22

normal A-a gradient

Answer 22

global hypoventilation

Question 23

widened A-a gradient

Answer 23

underlying lung disease (intrapulmonary shunt)

Question 24

indications for mechanical ventilation

Answer 24

1. airway protection for a patient with decreased level of consciousness
2. hypercapnic respiratory failure due to airway, chest wall, or respiratory muscle disease
3. hypoxic respiratory failure
4. circulatory failure, in which sedation and mechanical ventilation can decrease the oxygen cost of breath