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3.24 > Lecture 19: Pharmacology of cough and breathing problems > Flashcards

Lecture 19: Pharmacology of cough and breathing problems Flashcards

1
Q

What happens with a cough?

A

Deep inspiration followed by a build up of intra-thoracic pressure against a closed glottis - glottis opens and you have a rapid expulsion of air and the sound

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2
Q

What are the receptors for a cough reflex?

A
  • Laryngeal and tracheobronchial
  • Diaphragm
  • Pleura
  • Oesophagus
  • Non myelinated c fibres
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3
Q

What is the cough centre?

A

Integration of afferent fibres in the medulla, separate to centres which control breathing

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4
Q

What are the afferent nerves of the cough reflex?

A
  • Ipsilateral vagus nerve
  • Glossopharyngeal, Phrenic
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5
Q

What are the efferent nerves of the cough reflex?

A
  • Phrenic and sponimotor nerves
  • Recurrent laryngeal
  • Vagal efferents to bronchial tree
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6
Q

What are the effector masculatures of the cough reflex?

A
  • Expiratory muscles
  • Diaphragm
  • Larynx
  • Bronchial smooth muscle
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7
Q

What is a productive cough?

A

Usually gets rid of secretions and foreign objects

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8
Q

What is an unprodcutive cough?

A

A dry cough that is persistent and served no useful purpose

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9
Q

What are common causes of persistent coughs?

A
  • Asthma
  • Rhinosinusitis (with post nasal drip)
  • oesophageal reflux (GERD)
  • Lung cancer
  • Chronic infections like TB and bronchitis
  • Medication - ACE inhibitors
  • Sleep apnea
  • Vocal cord dysfunction
  • COVID
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10
Q

What causes a wet cough?

A
  • Cold
  • Flu
  • Lung infection
  • Cystic fibrosis
  • COPD
  • Acute bronchitis
  • Bronchiectasis
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11
Q

How do you treat coughs above the larynx?

A
  • Application of a medication that forms a soothing coat over the inflamed membranous tissue - this is called a demulcent
  • Honey, thick sugar based syrups (with or without a central cough suppressant) and lozenges are useful for this purpose. Useful for about 30 minutes or so.
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12
Q

How do you treat coughs below the larynx?

A
  • Steam inhalation or water aerosol inhalations
  • Menthol, eucalyptus and benzoin tincture can help by stimulating the secretion of a thin layer of mucus to protect the inflamed area.
  • Menthol can block TRPV1 channels
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13
Q

What can suppress a cough centrally?

A

Opioids can suppress neauronal activity in the cough centre in the medulla

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14
Q

What opiods are used to suppress a cough?

A
  • Codeine and methadone
  • Dextromethorphan and pholcodeine
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15
Q

Describe codeine and methadone for suppressing coughs

A

Activates µ-opioid receptors. Methadone and diamorphine linctus is sometimes helpful to lung cancer patients – they can help with pain relief (analgesia) and better sleep (sedation).

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16
Q

Describe dextromethorphan and pholcodeine for suppressing coughs

A

act via o-opioid receptors. They are anti-tussive without offering pain relief. Dextromethorphan is common in OTC cough medicines.

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17
Q

Describe ATP as a key modulator of the cough reflex

A

ATP is released from damaged or inflamed cells and acts on specific receptors, cactivates the P2X3 and P2X2/3 receptors on sensory neurones within the airway mucosa. Activation of these receptors by ATP has been shown to enhance the cough reflex

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18
Q

What is mucus made up of?

A
  • Water (98%)
  • salts (1%)
  • mucin glycoproteins (0.5%)
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19
Q

What is the function of mucus?

A

Protective and clears foreign particles, trapped pathogens and lysed material from immune cells from the lungs

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20
Q

What is the role of bronchial cilia?

A

Play a key role in moving the mucus upwards and out of the lungs- so the mucus has to be the correct thickness

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21
Q

Name mucolytics

A

N-acetylcysteine (NAC) and carbocysteine

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22
Q

What do mucolytic do?

A

Break apart the di-sulphide bonds in the mucins. This decreases the viscosity of mucus.

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23
Q

What is dornase alpha?

A

Mucolytic enzyme - used in patients with cystic fibrosis

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24
Q

How does dornase alpha work?

A

Breaks down DNA polymers found in the thickened mucus and so makes it less viscous

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25
Q

What do expectorants do?

A

Expectorants such as guaifenesin encourage productive cough by stimulating secretion of mucus (more watery overall). Easier to clear.

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26
Q

What are the muco kinetic drugs and what do they do?

A

Beta 2 adrenoreceptor agonists - cilia beat faster

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27
Q

What are the muco regulators?

A
  • Anti muscarinics
  • Glucocorticoids
28
Q

What produces surfactants?

A

Type II pneumocytes

29
Q

What do surfactants do?

A

Lower surface tension on the alveolar surface- reduced inner pressure within the alveoli (and equalizes pressure between big and small alveoli)

Also prevents so much fluid coming from the capillaries into the lungs-kind of sealant.

30
Q

What would heppen without surfactants?

A

The small alveoli would collapse and gas exchange would be severely compromised.

31
Q

What is Infant Respiratory Distress syndrome?

A

IRDS occurs soon after birth, is associated with breathing difficulties, blue colouration of the baby and extended periods of breathing cessation (apnoea).

32
Q

What happens in IRDS?

A

Alveoli collapse leaving larger spaces that get filled with cellular debris. This Diffuse Alveolar Damage (DAD) - layer of dead cells, proteins and surfactant on the surface of the alveoli (so-called hyaline membranes).
Gaseous exchange is severely compromised.

33
Q

What are the treatment options for IRDS?

A
  • Pre-treatment of the mother before she gives birth with glucocorticoids can enhance surfactant secretion and prevent many cases.
  • Treatment with 40% oxygen therapy, mechanical ventilation, fluids and artificial surfactants are used to combat the symptoms.
  • Artificial surfactants for intratracheal application include: colfosceril palmitate, poractant-α and beractant
34
Q

What is apnoea?

A

Stopping breathing

35
Q

What is dyspnoea?

A

Difficulty breathing

36
Q

What are the two types of apnoea?

A
  • Obstructive
  • Central
37
Q

What is obstructive apnoea?

A

collapsible airways, narrow airways.

38
Q

What is central apnoea?

A

neurological misfunction/imbalance no inspiration.

39
Q

What can prolonged apnoea lead to?

A

impair brain oxygenation.

40
Q

What are the risks of untreated sleep apnoea?

A
  • Depression
  • Diabtetes
  • Heart failure
  • High blood pressure
  • Concentration and memory problems
41
Q

What are the devices used to hold airways open?

A
  • Mandibular advancement devices (MADs).
  • CPAP (continuous positive airway pressure)
42
Q

What are analeptics?

A

Respiratory stimulants

43
Q

Name respiratory stimulants

A
  • Doxapram (Carotid)
  • Aminophylline (central effect on the NTS)
44
Q

What are favoured over respiratory stimulants in most clinical trauma situations?

A

Mechanical ventilators

45
Q

What can be used to stimulate breathing especially after fainting?

A

Irritant vapours (such as ammonia)

46
Q

What can be used as a respiratory stimulant for preterm neonates.

A

Aminiphylline

47
Q

What drug has moderate benefit for central sleep apnoea?

A

Acetazolamide

48
Q

What are the causes of chronic dyspnoea?

A
  • cardiovascular disease,
  • pulmonary disease, COPD, pulmonary
  • hypertension, pulmonary embolism.
  • Interstitial lung disease
  • psychogenic dyspnoea (anxiety)
  • deconditioning/obesity
  • anaemia
49
Q

What are the CV problems linked to dyspnoea?

A
  • Heart failure
  • Pulmonary hypertension
  • Pulmonary embolism
50
Q

What is forward heart failure?

A

Heart is too weak to perfuse the lungs

51
Q

What is back heart failure?

A

increased pulmonary venous pressure and movement of fluid into the air spaces of the lungs (pulmonary oedema)

52
Q

What is pulmonary hypertension?

A

narrowing of the arteries going to the lungs- less perfusion and right sided heart failure

53
Q

What is pulmonary embolism?

A

block of the vessels in the lungs

53
Q

What is pulmonary embolism?

A

block of the vessels in the lungs

54
Q

What does left ventricular failure cause?

A

Back pressure and fluid build up in the lungs

55
Q

What is pulmonary edema?

A

Build up of fluid in the air sacs

56
Q

What is the treatment for Acute, significant pulmonary oedema?

A

Oxygen

57
Q

What is the treatment for heart failure?

A

Diuretics (e.g. furosemide) help reduce the oedema and vasodilators.
Longer term ACE inhibitors are then used to reduce the load on the heart.

58
Q

What are the treatments for embolism?

A

Acute pharmaceutical treatment includes oxygen, thrombolysis and anticoagulation.

59
Q

What is type 1 respiratory failure?

A

Low oxygen in the blood - hypoxemia. It is assossicated with damage to lung tissue which prevents adequate oxygenation of the blood. However, the remaining normal lung is still sufficient to excrete carbon dioxide.

60
Q

What disease are type 1 respiratoty failure?

A
  • Pneumonia
  • Acute respiratory distress syndrome
  • Pulmonary fibrosis
  • Pulmonary hypertension.
61
Q

How do you treat type 1 respiratory failure?

A

High oxygen therapy 85-95%

62
Q

What is type II respiratory failure?

A

Alveolar ventilation is insufficient to excrete the carbon dioxide being produced. It affects the lung as a whole.

63
Q

What disorders are type II respiratory failure?

A
  • COPD
  • Severe asthma
64
Q

What are the characteristics of type II respiratory failure?

A
  • Normal/low PO2 (or > 60mmHg)
  • high PCO2 (hypercapnia) (>50mmHg).
  • respiratory acidosis (pH <7.35)
65
Q

How do you treat type II respiratory failure?

A

Low concentration O2 therapy (24-28%)

66
Q

Why do you not use high oxygenation in type II respiratory failure?

A

It can worsen the condition by suppressing the body’s drive to breathe. drive to breathe is based on the levels of CO2 in the blood, not the level of oxygen. When high levels of oxygen are given, the body may perceive that there is enough oxygen and reduce the drive to breathe. This can cause the CO2 levels in the blood to rise, leading to further respiratory distress.

3.24 (28 decks)

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