VIVA QUESTIONS

Question 1

Define APO

Answer 1

An accumulation of fluid in the tissues of the lung and alveoli, forming a barrier to gas exchange

Question 2

What are the two main causes of APO?

Answer 2

1. Haemodynamic distubances (LVF), and

2. Increased capillary permeability

Question 3

What is the cause of Paroxysmal Noctural Dyspnoea?

Answer 3

Negative feedback system based upon hypoxia. Metabolism slows during sleep, HR slows, reduces myocardial force of contraction and CO. Exacerbates already hypoxic system. HR speeds up to compensate, further hypoxia, back pressure of blood in pulmonary system, cycle continues until person is woken with APO.

Question 4

Describe the pathphysiology of cardiogenic APO

Answer 4

LVF->ventricle stiffens->LV pressure increases->pressure back on atria and pulmonary circulation->pulmonary capillary pressure increased->fluid portion of blood forced into interstitium and alveoli->insufficient lymphatic drainage to cope->barrier to gas exchange, surfactant washout(decreased surface tension)->increased work of breathing

Question 5

List the symptoms of APO

Answer 5

SOB, pale, cyanotic, crackles/gurgles on auscl, tachycardic, hypertensive, decreased O2 sats, cardiac wheeze, ALOC

Question 6

Describe the management of APO

Answer 6

DRABC, posture (upright), high flow oxygen, monitor, GTN (systolic of 100 as a guide) per 5 mins, consider salbutamol for wheeze???

Question 7

Describe the action of GTN

Answer 7

Absorbed by mucosa into vascular system, metabolised by vascular smooth muscle to form nitric oxide, decreased intracellular Ca2+ lvls, smooth muscle relaxation and vasodilation, = decreased preload, afterload, reduced myocardial workload and oxygen demand

Question 8

WHy are phosphodiesterase inhibitors contraindicated in the use of GTN?

Answer 8

They inhibit the breakdown of cAMP and cGMP resulting kin elevated levels, potentiate the effect and duration of GTN

Question 9

List the 3 main cardiac causes of APO

Answer 9

CCF, LVF, mitral valve regurgitation

Question 10

List the 3 main non-cardiac causes of APO

Answer 10

ARDS, toxic inhalation, direct lung injury

Question 11

What is the difference between osmotic, oncotic, and hydrostatic pressure?

Answer 11

Osmotic refers to the pressure produced by a solution due to a differential of solute concentration, oncotic refers to the pressure exerted on a solution by proteins and hydrostatic pressure refers to the pressure exerted on a semi-permeable membrane by a solution

Question 12

What is oedema?

Answer 12

excess fluid in the interstitial space

Question 13

What are the 4 causes of oedema?

Answer 13

1. Increased hydrostatic pressure
2. decreased oncotic pressure
3. increased vascular permeability
4. lymphatic blockage

Question 14

What do the pneumonics COP, CHP, IFOP and IFHP mean?

Answer 14

COP = capillary oncotic pressure (protein levels)
CHP = capillary hydrostatic pressure (blood pressure)
IFOP = interstitial oncotic pressure (proteins in interstitium)
IFHP = interstitial hydrostatic pressure (lymphatic drainage)

Question 15

What are the two main physiological effects of APO, and what symptoms do they produce?

Answer 15

1. increased thickness of respiratory membrane = decreased gas exchange and hypoxemia,
2. Washout of surfactant = alveolar collapse, increased WOB, and V/Q mismatches

Question 16

WHy would a patient suffering APO become acidotic?

Answer 16

1. Decreased gas exchange = increased pCO2, low pH (respiratory acidosis)
2. increased anaerobic respiration of tissues because of hypoxia leads to lactic acid production (metabolic acidosis)

Question 17

What is capillary epithelium breakdown and what can cause it?

Answer 17

Breakdown of the capillary wall, and can be caused by toxic inhalation, aspiration, and inflammatory mediators

Question 18

Why would adrenaline be contraindicated in APO?

Answer 18

It would vasoconstrict peripheral vessels and increase HR and force of contraction, which would increase myocardial workload (increased hypoxia on heart) and increased hydrostatic pressures within pulmonary vessels.

Question 19

Define Anaphylaxis

Answer 19

A severe form of life threatening allergic reaction caused by repeated exposure to an antigen (usually a protein), resulting in systemic inflammatory response initiated by IgE mediated mast cell degranulation, causing hypotension, bronchospasm, and oedema

Question 20

What is an antigen?

Answer 20

Molecule capable of initiating an immune response

Question 21

What is an allergen?

Answer 21

Its an antigen capable of initiating a type 1 hypersensitivity response in atopic people (means they have a predisposition to having allergic reactions

Question 22

What are mast cells and how do they initiate an immune response?

Answer 22

Mast cells are bags of granules located in loose connective tissue which wen stimulated release inflammatory mediators such as histamine and basophils, which are granulocytes similar to mast cells.

Question 23

Explain what effect mast cell degranulation has on H1 and H2 receptors

Answer 23

Mast cell degranulation releases histamine which stimulates H1 receptors in the bronchial smooth muscle causing bronchoconstriction and increased vascular permeability leading to oedema, and H2 receptors in the stomach which release gastric acid

Question 24

List the clinical features of anaphylaxis

Answer 24

Bronchospasm, conjunctivitis, rhinitis, itching, angioedema, peripheral vasodilation

Question 25

List the symptoms of anaphylaxis

Answer 25

SOB, tachypnoea, hypotension, airway compromise, rash, nausea and vomiting

Question 26

Discuss the role of adrenaline in anaphylaxis

Answer 26

Adenaline has a positive inotropic, chromotropic, and dromotropic effect –> peripheral vasoconstriction, increased HR and FOC, bronchodilation, decreased mucous production, decreased mast cell degranulation

Question 27

What is the prehospital treatment of anaphylaxis?

Answer 27

DRABC, high flow oxygen, posture, adrenaline 10mcg/kg up to 0.5mg IM every 5 mins if required, IV fluids for adequate BP (adults only), clinical support early for paeds, transport and notify.