Pulm Parenchymal Disease and Failure Flashcards
What structures make up the conducting zone
Trachea
Extra and intrapulmonary bronchi
Bronchioles (non-respiratory, terminal)
*Not respiratory bronchioles
What structures make up the respiratory zone
Respiratory bronchioles
Alveolar ducts
Alveolar sacs
Alveoli
How many alveoli in lungs
70 million (100 alveolar sacs per duct, 30 alveoli per sac)
about 500-1000 square feet
what type of pneumocytes work as being stem cells to replace alveoli
Type 2- as type 1 get damaged, type 2 proliferate and the area gets chunkier
How might inflammation affect the alveoli
1) from the airway
2) from the blood
thin, flat cells that primarily function in gas exchange by covering most of the alveolar surface
type 1 pneumocytes
cuboidal cells that produce and secrete surfactant, a substance that reduces surface tension in the alveoli, preventing them from collapsing
type 2 pneumocytes
What is the consequence of airway and alveolar flooding from lung disease
-surfactant loss
-stiff lungs
-Increased WOB
-Increased O2 consumption
What are the consequences of disease in the respiratory zone
1) Airway and alveolar flooding: surfactant loss, stiff lungs, increased work of breathing, Increased o2 consumption
2) Hypoxemia: O2 debt, respiratory failure
3) Systemic inflammation: thrombosis, organ dysfunction, leaky vessels
What are the clinical signs of respiratory zone disease
1) Restrictive pattern (rapid and shallow)
2) Crackles: fine (high pitched) or course (low pitched)
3) Dull to absent bronchovesicular lung sounds (if cant open to form crackles)
4) Hypoxemia
5) Respiratory fatigue
6) Systemic illness
7) Fever
What are you hearing with crackles in respiratory zone disease
airways popping open
fine/smaller airway = high pitched
course = low pitched
What are causes of respiratory zone disease
Vascular (bleeding, clotting, BP): hemorrhage, PTE
Infection: aspiration pneumonia
Toxin: anti-coagulation rodenticide, smoke, toxic gas
Trauma: strangulation, contusion, drowning
Anatomic: lung lobe torsion, airway obstruction
Metabolic: ?
Neoplastic: infiltrative, metastatic
Inflammatiory: ALO, ARDS, anaphylaxis
Degenerative: ??
How can you assess for pulmonary hemorrhage
PT/PTT - coagulation analyzer
Platelet count
How can you assess for pneumonia bedside
do a lung POCUS -> occurs right middle
How can you assess for strangulation NCPE
lung pocus (bilateral Cd)
How can you assess for anticoagulant rodenticide
PT/PTT
How can you assess for ALI or ARDS bedside
Echo
Thoracic Rads/CT
How do you determine platelet count
1) 100x objective
2) Count number of platelets in 10 fields of monolayer
3) Platelet number x 15,000 = platelet count
want about 10 platelets per high powered field
What are 2 differential diagnoses for bilateral wet lungs in the caudodorsal and perihilar lung regions
Cardiogenic pulmonary edema
NOn cardiogenic pulmonary edema
tell by Ao:LA ratio
.What typically causes ARDS
triggered by something else: trauma, pancreatitis, pneumonia, sepsis, shock etc.
WHat might cause pulmonary edema *
1) High pressure edema
-Left CHF (Cardiogenic)
-Fluid overload
2) Increased permeability edema
-ALI/ARDS
-Inhaled toxins
-Barotrauma
3) Mixed Cause
-Neurogenic (head trauma, seizures, electrocution)
4) Negative pressure (airway obstruction)
5) Re-expansion edema from chronic atelectasis
what neurogenic causes can cause pulmonary edema
head trauma
seizures
electrocution
What is the typical onset of ARDS
<72 hours
ARDS causes what on ultrasound
wet lungs - lots of B lines
ARDS causes what
1) Pulmonary capillary leak - bilateral diffuse infiltrates
2) Hypoxemia: P/F <200-300
3) Diffuse pulmonary inflammation: TTW, BAL
What other diagnostics are important in gauging how bad pulmonary disease is
SpO2
Arterial blood gas (what about venous)
Thoracic radiographs
Thoracic CT
the amount of O2 dissolved in plasma
SpO2
What is a normal PaO2 for an animal receiving supplemental oxygen
PaO2 = FiO2 x 5
How do you assess hypoxemia in a patient receiving supplemental oxygen
PF ratio = PaO2 / FiO2
FiO2 needs a decimal
What is a normal P/F ratio
500
What does P/F ratio mean
500= normal
<300= not great
<200 = really bad
<100 = terrible
How do you assess hypoxemia in a patient breathing room air
Aa gradient
should be <10
Does hypoxemia from hypoventilation have a normal Aa gradient
Yes <10
How do you characterize elevated Aa gradient indiciating hypoxemia from lung pathology
Mild: 10-20
Moderate: 20-30
Severe >30
normal is <10
How do you calculate A-a gradient
PAO2 - PaO2
PAO2 = FiO2 [Pb-Ph2o] - (PaCO2)/R
PaO2 = given on the blood gas
T/F: Co2 diffuses more easily than O2
true
What are the indications for mechanical ventilation **
1) Severe hypoxemia despite O2 supplementation
PaO2 <60mmHg
SpO2 <90%
2) Severe hypoventilation despite therapy
PaCO2 >60mmHg
3) Respiratory fatigue
4) Severe hemodynamic compromise
If giving O2 supplementation, what values of hypoxemia indicate you should start mechanical ventilation
PaO2 <60 mmHg
SpO2 <90%
What hypoventilation value should you start mechanical ventilation despite therapy
PaCO2 >60mmHg
With lots of edema, why might flow by oxygen do anything
without surfactant, the animal wont even open up their alveoli
When doing positive pressure ventilation, what should the Positive end expiratory pressure (PEEP) be?
5-10 cm H20
-Prevent alveolar and small airway collapse
-Recruit collapsed alveoli
-Helps pop open alveoli and keeps the alveoli open (even when exhaling)
What value should PEEP be
5-10 cmH20
Animals that have to go on positive pressure ventilation have a bettr outcome if ventilated for
hypoventilation vs pulmonary disease
ex:
(57%), pulmonary contusions (40%), aspiration pneumonia (30%), ARDS (8%)
