Respiratory System Flashcards
Anatomy of upper and lower respiratory tracts
Upper
Nasal turbinates Nares Epiglottis Larynx Oesophagus
Lower
Trachea Carina Primary bronchus Bronchiole Lower lobe Diaphragm
Anatomy of lower respiratory tract
Trachea
Cartilage rings Primary bronchus Root of lung Visceral pleura Cartilage plates Secondary bronchus Tertiary bronchi Smaller bronchi Bronchioles Terminal bronchiole Respiratory bronchiole Alveoli
Anatomy of terminal airways and alveoli
Microscopic air tube
Microscopic blood vessels
Capillaries
Alveoli
Breathing and respiratory
External respiration- is what we call breathing - this occurs in the lungs where oxygen diffuses into the blood and carbon dioxide diffuses into the alveolar air
Internal respiratory occurs in the metabolising tissues, where oxygen diffuses out of the blood into the tissues and carbon dioxide diffuses out of the cells and into the blood
Respiratory processes
Neural control - respiratory centres in the brain control inspiration rate and death
Ventilation - air entry to lungs
Perfusion - blood supply to the lungs
Diffusion - oxygen tea spot to RBCs
Why do we need oxygen
Oxidative phosphorylation:
- adenosine triphosphate (ATP) is the universal energy source of cells to facilitate all chemical processes in cells
- ATP is produced through a series of chemical reactions in the inner compartments of mitochondria, the final stages of which require oxygen
The body presses 90 seconds supply of ATP therefore it is necessary to breathe continuously in order to supply enough oxygen for the on going generation of ATP
Tissue viability in anoxia
Brain cell death= 4-5 mins
Myocardium = 5 mins
Kidneys and liver = 10 mins
Skeletal muscle= 2 hours
Anatomical differences
As compared to an adult a child has
A relatively large occiput = flexion of the neck can cause partial obstruction
A relatively large tongue = potential for obstruction
Changing dentition over time = no teeth/ milk teeth/ adult teeth/ loose teeth can be inhaled
Obligatory nose breathers under 6 months of age, risk of apnoea with nasal blockage
Anatomical differences
Narrow nasal passage= smaller airways = greater resistance to airflow, exacerbated by any secretions
Frequently enlarged tonsils/ adenoids= increased resistance to airflow and potential obstruction
Sharp angle between orophayrnx and glottis = enables young babies to breath and feed at the same time
Anatomical differences
Smaller airways diameter= any obstruction/ inflammation causes greater resistance to flow and so more sever distress ( infants are extremely vulnerable to atelectasis and exploratory wheeze)
Airway walls that are less rigid = tendency to collapse when in distress giving greater resistance to air flow
Thicker alveoli walls at birth = decreases the efficiency of gas exchange
Anatomical differences
Fewer alveolar numbers (alveolar clusters develop over the first 8 years of life) less efficient gas exchange
Ribs that are more horizontal = lessening the chest wall movement and tidal volume
Rib cartilage that is more compliant = less outward recoil and tidal volume
Weaker intercostal muscles = less able to lift the rib cage up and forward and so tidal volume decreases
Surfactant
Action of surfactant
- reduces water surface tension
- prevents collapse on expiration
Produced by type 2 alveolar pneumocystis
- 22-24 weeks production begins
- 32-36 weeks sufficient concentration present
Production of surfactant is induced by
- glucocorticoids eg cortisol
- catechilamines eg adrenaline
Acute respiratory failure
An acute clinical situation in which alveolar ventilation fails to maintain arterial blood gasses at physiological values
NB there may be acute respiratory failure on top of existing chronic respiratory failure
Cause of acute respiratory failure
Drug overdose, spinal cord injuries, stroke
Trauma, injury affecting ribs and or lungs
Infection, pneumonia, croup, epiglottitis, bronchiole ‘tis
Airway obstruction, foreign body, asthma, allergic reaction
Burns inhalation of hot or corrosive fumes
Vulnerability to respiratory tract infections in children
At birth
- immunologically immature
- has benefit of placental transfer of maternal IgG and IgA
First six months
-anatomical risk eg narrower bronchial tree
-environmental risk include
Exposure to tobacco smoke
Formula feeding- on immunological advantages
Child care/siblings - infection
Poor socio-economic status and housing
Vulnerability persists, but to a lesser degree during first 7-8years of life
Clinical assessment of ARF
Clinical signs and symptoms of ARF include
Confusion, sleeping and loss of consciousness
Dyspnoea- subject sensation of difficult or laboured breathing air hunger, shortness of breath, feeling like you can’t get enough air
Cyanosis- bluish colour on your skin, lips, and fingernails
Increased work of breathing
Clinical assessment of ARF
Signs of increase work of breathing include
Tachypnoea
Intercostal and subcostal recession
Use of accessory muscles
Wheezing
Tachycardia
Sweating
Head bobbing, nasal flaring and grunting in young babies
Cyanosis
Blueness of the skin and mucous membranes caused by excessive deoxygenation of Hb in the capillaries
Immediate management
Aims of immediate management are
Restore effective alveolar ventilation by
- supplemental O2
- optimal position of patient
- remove any visible airway obstruction
- intubation
Identify and treat underlying cause
Instigate mechanical ventilation if clinically indicated - will require ITU admission
Summary
Children are susceptible to respiratory problems due to their unique anatomy
Additionally children are vulnerable to RTI due to their immature immune system
Assessment of a child for signs and symptoms of respiratory distress is an important skill for all nurses to develop , as well as identifying when to instigate interventions
What is asthma
Asthma is a long term condition that results in inflammation and episodic narrowing of the lower airways
This narrowing of airways results in an increased resistance to airflow, and this gives rise to symptoms that include breathlessness, tightness in the chest, coughing and wheezing
Aetiology of asthma
Asthma is thought to arise as a result of a combination of genetic sesceptibility and early exposure to environmental-allergens
Around 60% of all asthma cases are hereditary- if a person has a parent with asthma, they are 3 to 6 times more likely to develop asthma than someone who does not have a parent with asthma
Stops- asthma is often found as part of a triad of eczema, asthma and hay fever. And this is referred to as atopy this runs in families
Three key features of asthma
Asthma is chronic respiratory condition leading to
Airway inflammation
- medium and small airways
- mucosal oedema and mucus secretion
Intermittent airflow obstruction
-airway smooth muscle contraction/ construction
Bronchial hyper-responsiveness to triggers
-smoke, pets, exercise, weather, infections, dust, mould, pollen, emotions
Asthma
Environmental factors-genetic predisposition
Bronchial inflammation
Bronchial hyper/reactivity and trigger factors
Oedema
Bronchi constriction
Increased mucus production
Airways narrowing
Cough, wheeze, breathlessness, tightness I gotta the chest
Pathology of asthma
Hyperinflated alveoli
Constricted smooth muscles
Degranulation of mast cells
Mucus accumulation
Thick mucus plugs
Features in chronic asthma and
In long term asthma the flow long airway remodelling or change in the airways are seen
. Fibrosis
.increased number and size of mucous- producing cells
.hypertrophy of smooth muscle and increased vascularisation
When these are present they are markers of persistent symptoms and resistance to treatment
Making a diagnosis of asthma
Asthma is a clinical diagnosis starting with the history and examination
A single wheezy episode is not asthma
Reaching a diagnosis can take weeks, months or every years, particularly in a young child
During this time the child may have a trial of treatment and test to help arrive at a diagnosis
This can be frustrating and worrying time for parents
Features suggestive of asthma
Persistent/ recurrent symptoms that include nocturnal cough, wheeze, cough, breathlessness
Symptom-free intervals
Coughing after exercise and or with crying/ laughing
Variable reduction of airway function e.g measured by peak exploratory flow
Family history of atopy/ asthma
Good response to asthma drug treatment
Potential trigger factors
Acute asthmatic episodes may be triggered by
Viral infections
Inhaled allergens e.g house dust mite, car dander
Environmental pollution
Exercise
Specific foods
Psychological stress
Wheezing
Wheezing is defined as
A continuous, high pitched musical sound coming from the chest it must be distinguished from other respiratory sounds
In general the earlier the onset of wheeze, the better the prognosis
Asthma attack
The sudden onset of breathing difficulty is described as an asthma attack
During such an attack breathing becomes increasingly difficult, the child can become tried due to the work of breathing
They may given an account of having benefited from their in healers or from exhaling through pursed lips
The child may also describe their chest as feeling tight
Acute asthma getting worse
Look out for the child who
Can’t complete sentences in one breath
Is too breathless to talk
Is tiring
Is using their accessory muscles
Has a low pulse oximetry reading
Is breathing very fast
- 40/minute in under 5 years
- 50/minute in under 5s
Has a fast heart rate
- 120/minute in under 5years
- 130/minute in 2-5 years old
Has a low peak flow
-50% of predicted best
Peak flow
A simple measurement of how quickly you can blow air out of your lungs
A rate of flow not volume of air
Measured in litres per minute L/min
Important in monitoring asthma, ideally as part of an individualised action plan flagging when to seek a medication review
It is probably less helpful in an acute attack as technique may be suboptimal and it may exacerbate the attack
Peak exploratory vs high in children
Taller the child the high the peak flow of
Pharmacotherapeutics
Relievers:
Used to rapidly reverse bronchi construction and associated symptoms
Preventers
Take daily on a long term basis to control presistent asthma
Emergency drinks
Used in for severe life threatening asthma
The treatment of asthma
Medications are designed to interfere with the various areas of the pathology seen in asthma
Smooth muscle contraction
Inflammation
Children with a high probability of asthma are started on a diagnostic trial of treatment
The recommended guideline for children adopts a stepwise approach
Step wise approach
Regular prevention
-very low dose ICS
Initial add on preventers
- very low dose ICS
- add inhaled LABA
Additional add on therapies
- no response to LABA-stop LABA and increase does of ICS to low does
- if benefit from LABA but control still inadequate
- continue LABA and increase ICS to low does
- If Benidorm from LABA but control still inadequate
- continue LABA and ICS and consider trial of other therapy
High dose therapies
- consider trials of
- increasing inhaled corticosteroids up to medium does
- addition of a fourth drug- SLow release Theophilline
Questions
Will my child grow out of it
- boys are more likely than girls to grow out of asthma
- children with asthma, particularly of severe asthma, never outgrow it
Does avoidance of allergens reduce the severity of asthma
- where there is a history of symptom exacerbation or testing shows sensitisation to an allergen then yes
Does smoking cause asthma
-second hand slime is well know to cause asthma
Breasting and asthma
- breastfeeding is associated with a reduced risk of developing childhood asthma
Summary
A chronic inflammatory disorder of the airways
The inflammation leads to wheezing, breathlessness, tightness in the chest, cough
Widespread but variable obstruction to airflow
Increase in bronchial sensitivity
Many cellular elements play a role: mast cells, eosinphils, T- cells, macrophages, neutrophils and epithelial cells
Pharmacotherapeutic management needs regular review for optimum control
Lesson summary
An understanding of normal anatomy and
