Care Lecture 2: ARDS and Pneumothorax

gas exchange

the availability of hemoglobin and its ability to carry oxygen from alveoli to cells for metabolism and to carry carbon dioxide produced by cellular metabolism from cells to alveoli to be eliminated

ventilation

movement of air in and out of the lungs; the lung's ability to expand and retract

oxygenation

the process of delivering oxygen to the blood

hypoxemia

deficient amount of oxygen in the blood; low partial pressure oxygen (PaO2); reduced O2 levels in arterial blood

hypoxia

lack of O2; insufficient O2 to cells

-O2: breathe in O2 to alveolar level & capillaries

-CO2: breathe out CO2/cellular waste

what happens to O2 and CO2 during oxygenation?

alveolar capillary membrane

gas exchange structure that contains the alveoli and the capillaries surrounding the alveoli; central component of gas exchange in lungs

negative pressure

what type of pressure pulls in the oxygen from the air?

high concentration --> low concentration

what direction does oxygen flow in?

ischemia or cell death

what happens to the body when oxygen is not released into circulation?

-↑ RR (due to lack of oxygen)

-↓ O2 sat

-↑ HR

-cyanosis and pallor

-clubbing

-adventitious lung sounds

what physical changes would you anticipate seeing in your patients that exhibit impaired ventilation/gas exchange disorders?

body may be able to get O2 it needs, but if there is not enough to reach hemoglobin capacity & give blood to rest of the body = gas exchange problem

how can gas exchange affect/impair the hematological system?

acute respiratory distress syndrome (ARDS)

a sudden and progressive form of acute respiratory failure in which the alveolar-capillary membrane becomes damaged and more permeable to intravascular fluid

begin to fill w/ fluid --> can't retract and expand correctly

what happens to alveoli in acute respiratory distress syndrome (ARDS)?

ABGs

measures the balance of oxygen and carbon dioxide in your blood to see how well your lungs are working; shows us the adequacy of oxygenation and ventilation

-pH

-PaO2

-PaCO2

-HCO3

-SaO2

what are the usual components of an ABG?

PaO2

component of an ABG that measures the pressure of oxygen dissolved in your blood; helps show how well oxygen moves from your lungs to your bloodstream

80-100 mmHg

what is the normal range of PaO2?

PaCO2

component of the ABG that is the measure of carbon dioxide within arterial blood; often serves as a marker of sufficient alveolar ventilation within the lungs

35-45 mmHg

what is the normal range of PaCO2?

HCO3

component of the ABG that measures the calculated concentration of bicarbonate in arterial blood

22-27 mEq/L

what is the normal range of HCO3?

pH

component of the ABG that measures the acid-base balance of the blood

7.35-7.45

what is the normal range of pH on an ABG?

SaO2

component of the ABG that represents oxygen saturation

92-100%

what is the normal range of SaO2 on an ABG?

> 400

what is a normal PaO2/ FiO2 (P/F) ratio?

PaO2 remains the same despite FiO2 being increased

in someone with moderate-severe acute respiratory distress syndrome (ARDS), what is true of the relationship between PaO2 and FiO2?

-dyspnea

-refractory hypoxemia

-↓ lung compliance

-diffuse pulmonary infiltrates

when alveoli fill with fluid, what might this lead to in the body?

tidal volume

the amount of air someone breathes in and out in one breath

sepsis = most common cause

what is the most common cause of acute respiratory distress syndrome (ARDS)?

can be direct or indirect

**direct = pathogen comes in contact w lungs; indirect = ARDS develops d/t problem somewhere else in the body

what is true about injury causing acute respiratory distress syndrome (ARDS)?

-aspiration

-viral/bacterial pneumonia

-sepsis

-chest trauma

-embolism

-near-drowning

-oxygen toxicity

what are some direct lung injuries that can lead to acute respiratory distress syndrome (ARDS)?

-sepsis (gram-negative)

-severe massive trauma

-acute pancreatitis

-anaphylaxis

-multiple blood transfusions

-narcotic drug overdose

-severe head injury

-shock states

what are some indirect lung injuries that can lead to acute respiratory distress syndrome (ARDS)?

surfactant

substance that maintains alveolar stability and prevents alveolar collapse

alveoli = unstable & collapse (atelectasis)

what happens in the body when surfactant is decreased or becomes inactivated?

refractory hypoxemia

a classic sign of acute respiratory distress syndrome (ARDS) which occurs when a patient's condition does not improve despite higher concentrations of O2; underlying cause is a change in the compliance of the lungs

-mild dyspnea, tachypnea

-cough

-restlessness

-lungs = normal or fine, scattered crackles

-mild hypoxemia

-respiratory alkalosis

-CXR = normal/minimal interstitial infiltrates

what are some clinical manifestations during the mild stages of acute respiratory distress syndrome (ARDS)?

-dyspnea

-restlessness

-↑ RR w/ accessory muscle use

-↑ HR

-nasal flaring

-diaphoresis

-cyanosis & pallor

-scattered/diffuse crackles & rhonchi

-CXR shows diffuse infiltrates (white out or white lung)

what are some clinical manifestations during the moderate-severe stages of acute respiratory distress syndrome (ARDS)?

beginning of ARDS = ↑ RR --> as ARDS progresses, RR will ↓ as respiratory muscles weaken

on a ventilated patient with acute respiratory distress syndrome (ARDS), what is true of their respiratory rate?

ARDS may occur within 1 week of a known clinical insult or new/worsening resp symptoms

what are some diagnostic findings in acute respiratory distress syndrome (ARDS) regarding timing?

bilateral opacities --> not explained by effusions, lobar/lung collapse, or nodules

what are some diagnostic findings in acute respiratory distress syndrome (ARDS) regarding a chest x-ray?

FiO2

the amount of oxygen in inspired air that is composed of oxygen; the concentration of oxygen in the air we breathe (ex: supplemental oxygen that you are giving the patient)

PaO2/FIO2 ratio > 200 to ≤ 300

describe the P/F ratio in mild acute respiratory distress syndrome (ARDS) with PEEP or CPAP being ≥ 5 cm H2O

PaO2/FIO2 ratio 100 to ≤ 200

describe the P/F ratio in moderate acute respiratory distress syndrome (ARDS) with PEEP or CPAP being ≥ 5 cm H2O

PaO2/FIO2 ratio < 100

describe the P/F ratio in severe acute respiratory distress syndrome (ARDS) with PEEP or CPAP being ≥ 5 cm H2O

1. injury/exudative phase

2. reparative/proliferative phase

3. fibrotic phase

what are the 3 phases of acute respiratory distress syndrome (ARDS)?

within 1-7 days after initial insult to lung/host

when does the injury/exudative phase of acute respiratory distress syndrome (ARDS) occur?

damage to alveolar-capillary membrane

↓

fluid crosses A-C membrane

↓

fluid enters alveolar space

↓

neutrophils rush to the scene d/t damage

↓

heightened inflammatory response

describe the pathophysiology of the injury/exudative phase of acute respiratory distress syndrome (ARDS)

-pulmonary edema

-V/Q mismatch

-atelectasis

-↓ lung compliance

-↑ RR

-↓ tidal volume (VT)

-respiratory alkalosis

-hypoventilation

neutrophils that rush to the lung during the injury/exudative phase of acute respiratory distress syndrome (ARDS) lead to what changes in the body?

they must generate ↑ airway pressures to inflate "stiff" lungs

why will someone with acute respiratory distress syndrome (ARDS) have an increased work of breathing?

1-2 weeks after insult to lung

when does the reparative/proliferation phase of acute respiratory distress syndrome (ARDS) occur?

neutrophils, monocytes, lymphocytes, fibroblasts = inflammatory response

what increases during the reparative/proliferation phase of acute respiratory distress syndrome (ARDS)?

tissue becomes dense and fibrous

what happens to tissue during the reparative/proliferation phase of acute respiratory distress syndrome (ARDS)?

-↑ pulmonary vascular resistance

-pulmonary HTN

-↓ lung compliance

-↑ airway resistance

-hypoxemia worsens

what changes might occur in the body during the reparative/proliferation phase of acute respiratory distress syndrome (ARDS)?

-persists = widespread fibrosis

-stops = lesions will often resolve

what is true of fibrosis during the reparative/proliferation phase of acute respiratory distress syndrome (ARDS) if the reparative phase persists vs if it stops?

when diseased lung is replaced by dense, fibrous tissue

when is the proliferative phase of acute respiratory distress syndrome (ARDS) complete?

2-3 weeks after insult (chronic/late phase)

when does the fibrotic phase of acute respiratory distress syndrome (ARDS) occur?

lung = completely remodeled by collagenous & fibrous tissues

for those who never fully recover from acute respiratory distress syndrome (ARDS) occur and remain in the fibrotic stage, what is true of the lung?

↓ surface area = hypoxemia continues

what is true of the surface area of the lung in someone in the fibrotic stage of acute respiratory distress syndrome (ARDS)?

pulmonary HTN

what is a common clinical manifestation that occurs during the fibrotic stage of acute respiratory distress syndrome (ARDS)?

refractory hypoxemia = hallmark sign

what is the hallmark characteristic of acute respiratory distress syndrome (ARDS)?

PEEP (positive end expiratory pressure)

a ventilator setting that increases the volume of air left in the lungs at the end of a normal expiration; helps open up ("recruit") collapsed alveoli

-normal = usually 5 cm H2O

-ARDS = around 10-20 cm H2O

what is a "normal" PEEP? what is a PEEP for acute respiratory distress syndrome (ARDS)?

too high of PEEP --> ↑ pressure on blood vessel --> vessel collapses to stop or slow down perfusion = ↓ venous return & ↓ CO

a PEEP that is too high can have what effect on venous return and CO?

-↓ venous return to right side of heart

-↓ preload

-↓ CO

-↓ BP

-↓ kidney function (↓ urine output)

what are some complications of a PEEP level that is too high?

can draw ABGs frequently

why is an ART line beneficial for a mechanically ventilated patient?

-infection (sepsis)

-VAP

-O2 toxicity

-pulmonary emboli or fibrosis

-barotrauma

-↓ CO

-dysrhythmias

-anemia

-DIC

-hypermetabolic state

what are some complications associated with acute respiratory distress syndrome (ARDS)?

barotrauma

occurs when fragile alveoli are overdistended with excess pressure during mechanical ventilation; results in alveolar air escaping from ruptured alveoli

-PaO2: 60 mmHg or higher

-adequate lung ventilation/patent airway

-SaO2 greater than 90%

-clear lungs on auscultation

what are some nursing management goals for a patient with acute respiratory distress syndrome (ARDS)?

-supplemental O2

-mechanical ventilation

-positioning strategies

-ET suctioning

-fluid management

-coughing/deep breathing

-hemodynamic monitoring

-wedge pressures

-vasopressors

what are some possible nursing interventions for acute respiratory distress syndrome (ARDS)?

ventilator-associated pneumonia (VAP)

a health care-acquired infection that develops in a person requiring invasive mechanical ventilation (via endotracheal intubation or tracheotomy tube)

blood is diverted from GI to resp. system to help meet body's demand for O2

why are patients with acute respiratory distress syndrome (ARDS) at an increased risk of stress ulcers?

IV fluids or medications

what can be done to correct decreased CO?

to correct hypoxemia

what is the primary goal of O2 therapy?

1. O2 administration

2. mechanical ventilation

3. low tidal volume ventilation

4. permissive hypercapnia

5. PEEP

6. prone positioning

7. ECMO

what is included in best practices for care of the patient with acute respiratory distress syndrome (ARDS)?

permissive hypercapnia

elevated arterial PaCO2 that results from hypoventilation of mechanically ventilated patients that is aimed at reducing ventilator-associated lung injury

low tidal volume = ↓ risk for volutrauma & barotrauma

**volutrauma = damage in alveoli & movement of fluids/protein into alveolar spaces

why are patients with acute respiratory distress syndrome (ARDS) ventilated with a low tidal volume?

-supine = fluid pools in dependent regions of lung d/t gravity --> atelectasis

-prone = alveoli in posterior lung are given opportunity to reexpand

**prone position = ↓ amount of O2/PEEP needed in order to get patient's PaO2 up

why is prone positioning vs supine better for patients with acute respiratory distress syndrome (ARDS)?

more positive pressure ventilation/PEEP = less CO

what is the relationship between PEEP and CO?

preload

volume of blood in ventricles at end of diastole

afterload

the force or resistance against which the heart pumps; ability of the heart to push the blood out to all the systems

contractility

the ability of the heart to be able to pump

-inotropics/vasopressors (maintain BP)

-dopamine

-dobutamine (manage low BP)

-norepinephrine

-diuretics

-IV fluids

-sedation/analgesia

-neuromuscular blockers

what is involved in drug therapy for acute respiratory distress syndrome (ARDS)?

pneumothorax

condition that is caused by air entering the pleural cavity; results in a partial or a complete lung collapse

negative = between visceral pleura (surrounding lung) & parietal pleura (lining chest cavity)

what kind of pressure should normally be in the lung?

positive pressure

what kind of pressure is in the lung for a patient with a pneumothorax?

air in pleural space ↑ = lung volume ↓

what is the relationship between air in the pleural space and lung volume?

1. open pneumothorax

2. closed pneumothorax

how can a pneumothorax be classified?

open pneumothorax

type of pneumothorax in which air is entering through an opening in the chest wall

closed pneumothorax

type of pneumothorax in which there is no associated external wound; air enters pleural cavity from internal airways; no opening in chest wall

mild tachycardia/dyspnea

what are some clinical manifestations of a "small" pneumothorax?

-shallow, rapid respirations

-dyspnea ("air hunger")

-O2 desaturation

-no breath sounds over affected area

-CXR = show air or fluid in pleural space

-↓ lung volume

what are some clinical manifestations of a "large" pneumothorax?

1. spontaneous

2. iatrogenic

3. tension

what are the 3 types of pneumothorax?

spontaneous pneumothorax

type of pneumothorax that typically occurs due to the rupture of small blebs (air-filled sacs) on the surface of the lung, allowing air to leak into the pleural space

-smoking = ↑ bleb formation

-tall and thin stature

-male

-family hx

-past hx of spontaneous pneumothorax

**blebs can occur in healthy, young people or from lung disease

what are some common risk factors related to a spontaneous pneumothorax?

iatrogenic pneumothorax

type of pneumothorax that can occur due to laceration or puncture of the lung during medical procedures; can be attributed to excessive mechanical ventilation pressures, tearing during insertion of gastric tube, etc.

tension pneumothorax

type of pneumothorax that occurs when air enters the pleural space but cannot escape

accumulation of air in pleural space

↓

elevated intrapleural pressures

↓

compression of lung on affected side

↓

pressure on heart & vessels, pushing them away from affected side

↓

mediastinum shifts toward unaffected side, compressing "good" lung

↓

compromises oxygenation & perfusion

↓

venous return & CO decline

describe what happens in the body in someone who has a tension pneumothorax

open or closed

tension pneumothorax may result from what kind of pneumothorax?