WK 9- Respiratory Emergencies

Question 1

What are the tests used to address severity of pneumonia (acronym)

Answer 1

CURB-65 and smartcop

Question 2

What is curb-65

Answer 2

• Confusions
• Urea
• RR greater than 30
• BP → low
• Aged over 65
=Each ‘YES’ answer receives 1 point
1= Out pt 
2= In pt 
3-5= ICU

Question 3

What is the conduction zone

Answer 3

• Conduction zone extend to the terminal bronchioles→ lead air to the gas exchanging region of lung but contain no alveoli
• Anatomical dead space of the conduction zone is 150ml
• Roles of conducting zone include conduction, warming and humidifying air, cleansing the air that is breathed in

Question 4

What is the respiratory zone

Answer 4

• includes the respiratory bronchioles, alveolar ducts, alveoli → GAS EXCHANGE
• Pulmonary ventilation leads to internal respiration (cellular respiration; occurring inside the cell)

Question 5

How does ventilation vary in the lungs

Answer 5

-Ventilation does not occur equally throughout lung→ ventilation decreases from lower to upper regions of the lung due to the bottom of the lungs alveolar wall has higher compliance = more stretchy → can inflate more → air travels path of least resistance hence ventilation increases as head toward bottom of lung

Question 6

How does blood flow vary in the lungs

Answer 6

Also, normally, blood flow decreases from base to apex (less blood flow at the top of the lung)→ due to gravity→ more blood flow down the bottom of the lung means better alveolar gas exchange

Question 7

What is the ventilation perfusion ration

Answer 7

• The ventilation-perfusion ratio is expressed as (VA/) ̇Q ̇ where VA is alveolar ventilation and Q ̇ is blood flow
• When (VA ) ̇ is normal for a given alveolus and Q ̇is also normal for same alveolus then the ventilation-perfusion ratio is said to be normal (0.8)

Question 8

What happens if ventilation is compromised in the lungs

Answer 8

When (VA ) ̇ = 0, but there is still perfusion (Q ̇) of the alveolus, the ventilation-perfusion ratio is zero (as it would be 0/Q which will equal 0)

Question 9

What happens if perfusion is compromised in the lungs

Answer 9

When there is adequate (VA ) ̇ but zero Q ̇ then the ratio is infinity (Va/0= infinite)

Question 10

How does oxygen diffuse from alveoli into capillaries

Answer 10

Differences in partial pressure of O2 create a gradient that causes oxygen to move via diffusion from the alveoli to the capillaries and into the tissues
-ie. partial pressure in alveolus is 104mmHg and at the arterial end the PO2 in the capillary is 40mmHg, this causes o2 to move from high pressure to low pressure so O2 will move into the capillary

Question 11

What happens if the pressure in the alveolar pressure becomes greater than capillary blood pressure (not in terms of O2 but in terms of BP)

Answer 11

alveolar air pressure on outside compresses them → if alveolar air pressure > capillary BP → capillaries close = no blood flow
-Therefore anytime lung alveolar pressure becomes greater than capillary blood pressure → capillaries close and there is no blood flow

Question 12

What are the different zones of flow in the lungs

Answer 12

Zone 1: no blood flow during all portions of cardiac cycle
-Total alveolar capillary pressure in that area of lung never rises higher than alveolar pressure during any part of cardiac cycle (capillary is squashed by alveolar)
-Blood flow in zone 1 only occurs under abnormal conditions ie when pulmonary systolic arterial pressure is too low, there is increased arterial pressure
Zone 2: intermittent blood flow
-During peaks of pulmonary arterial pressure there is blood flow → because systolic pressure is greater than alveolar air pressure
-Diastolic pressure is less than alveolar air pressure → no blood flow during diastole
Zone 3: continuous blood flow
-Alveolar capillary pressure remains greater than alveolar air pressure during entire cardiac cycle → continuous blood flow

Question 13

What zones does a normal lung have

Answer 13

2 and 3

Question 14

How is respiration controlled

Answer 14

-controlled by several neurons on the brainstem
1. Dorsal respiratory group → located in the dorsal portion of the medulla → mainly causes INSPIRATION
2. Ventral respiratory group → located in the ventrolateral part of the medulla → mainly causes EXPIRATION
3. Pontine respiratory group → located dorsally in the superior portion of the pons → mainly controls rate and depth of breathing
o Pneumotaxic centre
o Apneustic centres

Question 15

What can affect gas exchange in the blood

Answer 15

• Obstruction to airflow –> COPD, tumour, pneumonia
• Impairment of diffusion across alveolar capillary membrane –> ie fibrosis or consolidation increasing thickness
• Loss of surface area–> ie atelactasis

Question 16

What us dyspoea

Answer 16

• Dyspnoea:

• State of mental anguish associated with inability to ventilate enough to satisfy demand for air
• Associated with:
  1. Abnormality of resp gases; hypercapnia>hypoxia
  2. Amount of work of resp muscles
  3. State of mind

Question 17

What does the assessment of a resp pt include

appearance, history, examination, monitoring and investigation

Answer 17

-Determine the cause of respiratory distress and determine the severity
Appearance--> 
-Level of consciousness
-Sweating
-Agitation
-Cyanosis or pallor
-Urticaria or angiodema
-Position patient holds themselves to help airway or breathing
History-->
-Nature of symptoms
-Onset of symptoms
-Progression of symptoms
-Associated symptoms
-Treatment so far
-Previous episodes
-Other significant past history
 Examination-->
-Airway Patency – Stridor, Swelling, Injury
-Respiratory Rate
-Depth of Respirations
-Work of Breathing
-Auscultation – air entry, wheeze etc
-Percussion- dull sounds? → pneumonia
-Tracheal deviation, neck veins etc
-Signs of chronic disease
-Pulse and Blood Pressure
 Monitoring-->
-Pulse Oximetry→ reads the relationship between O2 stats and pO2→ normal O2 sats are around 97%, don’t want them to get below 90% (think of oxygen dissociation curve→ after 90%, Hb affinity for O2 decreases, making it harder for O2 to bind
-End Tidal CO2
-Standard Monitoring P / BP
Investigation--> 
-Chest X Ray
-Arterial Blood Gas (ABG)
-ECG
-Spirometry
-Sputum Culture
-Pathology

Question 18

What are the supportive airway tx available for airway emergencies

Answer 18

AIRWAY= 
Position of patient to maintain airway→
-Jaw thrust
-Chin lift→ do not do if suspected spinal injury 
-Head tilt
-Lying on side
-Basic intervention→
-use an Oropharyngeal Airway (OPA) or 
 Nasopharyngeal Airway (NPA)
-think about→ sizes, position, use, complications (ie. Do not use nasopharyngeal is suspected basal skull fracture)
-Advanced intervention→ 
-Endotracheal Tube (ETT), Laryngeal Mask (LMA), Surgical

Question 19

What are the supportive airway tx for resp distress

Answer 19

Airway
-think about→ sizes, position, use, complications
BREATHING=
-Increase Fi02 (fraction of inspired oxygen)
-Oxygen delivery systems-> oxygen masks

Question 20

What are the pro’s and con’s of and the flow rate of a nasal cannula

Answer 20

Flow Rate : 2-6 l/min
-Problems: Variable and poorly predictable FiO, high flow rates difficult to tolerate, dries nasal mucosa, uncomfortable at higher flow rates (> 4 l/min)
Advantages: Comfortable at low flow rates, Allow patient to eat and drink, Cheap, No rebreathing occurs

Question 21

What are the pro’s and con’s of and the flow rate of a hudson mask

Answer 21

Flow Rate : 4-15 l/min
Problem: Maximum FiO2 less than 0.7 with 15 l/min, Variable and poorly predictable FiO2, Poor humidification with high FiO2, Rebreathing occurs with FiO2 < 0.35 (O2 flow < 4l/min)
Advantages: Comfortable (usually), Cheap, Allow a large variation in target FiO2

Question 22

What are the pro’s and con’s of and the flow rate of a rebreather mask

Answer 22

Maximum FiO2 achievable with O2 15 l/min : < 0.85→ Have reservoir with a one way rubber flap valve to collect CO2
Problem: Care with flow rates, faulty valves and consequent rebreathing
Advantages: Maximal FiO2 with a simple mask

Question 23

What are the pro’s and con’s of and the flow rate of a venturi mask

Answer 23

FiO2 able to be varied from 0.24 - 0.60
-Operates via a venturi device entraining room air in an oxygen jet
-Concentration is varied by adjusting the O2 flow rate and the entrainment aperture size
Delivers high flow of known concentration gas
Problem: Unable to deliver FiO2 > 0.6, FiO2 fluctuates in severe dyspnoea with high inspiratory flow rates
Advantages: More predictable control of FiO2, Relatively fixed in performance in the absence of severe dyspnoea (extreme PIFR), No rebreathing, Reasonable humidification at low FiO2

Question 24

What are the definitive tx for anaphylaxis, pneumonia, tension pneumothorax, asthma

Answer 24

• Anaphylaxis= Adrenaline
• Asthma= Bronchodilators
• Pneumonia= Antibiotics
• Tension Pneumothorax= ICC

Question 25

What cautions are needed when administering oxygen

Answer 25

• oxygen toxicity
• use with Bleomycin(Pulmonary and CNS toxicity), Paraquat
• Chronic Airway Limitation (“Hypoxic Drive”)
• Physical risks–> ie risk of o2 tank explosion

Question 26

What is hypoxic drive

Answer 26

Variations in CO2 provide the main stimulus to breathe in normal patients. Some patients with COPD have a decreased sensitivity to CO2 levels secondary to chronic exposure to higher CO2 levels and hypoxia provides backup support for the respiratory drive. Oxygen given in sufficient amounts can remove the remaining chemical stimulus to respiration and has the potential to cause respiratory depression (remove resp drive)

Question 27

How do you differentiate between viral and bacterial pneumonia

Answer 27

• viral
- not as high of fever
- might not hear crackles
- no lobar consolidation → resonant on percussion instead of dull (bacterial)
- short duration
• bacterial
-risk of complications
-could’ve had a viral infection prior and now become bacterial
-will have a longer duration and be more severe
-fever, vomiting, chills, purulent mucus, myalgia

Question 28

What is the MOA of hydrocortisone

Answer 28

-Hydrocortisone is a corticosteroid receptor agonist-> interacts with basic transcription factors to increase expression of specific target genes–> The anti-inflammatory actions of corticosteroids are thought to involve lipocortins, phospholipase A2 inhibitory proteins which, through inhibition arachidonic acid, control the biosynthesis of prostaglandins and leukotrienes

Question 29

What is the MOA of salbutamol

Answer 29

-B2 agonist on smooth muscles–> will bind to the receptor and cause vasodilation and prevent recruitment of WBC decreasing inflamm response