Summary Student nurse and registered nurse study guide notes to critical care nursing.
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Critical care course nursing
Instelling
Critical Care Course Nursing
Designed to Improve your confidence in your nursing care, written simply and to the point, this eye pleasing guide is to help your knowledge and confidence in your chosen profession on the shop floor. From some one who's been there and felt so completely lost and now I'm a nurse educator!
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Respiratory Anatomy The Lungs
Right- 3 lobes. Upper middle and lower
The system that’s gets oxygen in to the body, and carbon dioxide
Left- 2 lobes. Upper and lower
out.
Made of elasticated tissue enabling stretch and recoil. Each lung
is surrounded by 2 layers called pleura. Pleural fluid lies between
the 2 layers to stop friction and enable expansion.
The patient breaths in through the nose and mouth were the
air is warmed, filtered and moistened. It then passes along the
trachea and down into the lungs. Air enters the lungs via the L
and R bronchus, moves through the bronchioles and at the end
enters the alveoli. At the alveoli gas is exchanged, oxygen is
taken into the blood and carbon dioxide is removed and is
breathed out.
We don’t have to think about breathing, it’s natural and
unconscious, it happens when were awake or asleep.
Nasal cavity (Nose, Mouth and Pharynx) were air is warmed
moistened and filtered via cilia hairs.
Larynx (voice box) provides passage of air between pharynx and
trachea where it is further warmed, moistened and filtered.
Trachea Contains C shaped rings placed one on top of the other, The control of respiration falls to the respiratory centre in the
made of cartilage ensuring trachea stays open, branches at the brain.
carina into right and left main bronchus Cells in the PONS and upper MEDULLA are sensitive to the
Bronchi R and L, Right- 3 branches. Left- 2 branches presence of CO2 in the blood. When CO2 starts to build up, it is
detected by chemoreceptors in the walls of the aorta and
Bronchioles Smaller branches of the bronchus carotid arteries as the blood comes out of the heart. A message
is then sent to the respiratory centre. The respiratory centre
Alveoli Sacs, a single layer of cells thick. Each alveoli lies next to
sends impulses down both the phrenic nerve (to diaphragm) and
a capillary, enabling exchange of co2 and o2.
thoracic nerves (at the intercostal muscles) and these muscles
contract.
The contracting rib muscles push your ribcage up and out and
the contacting diaphragm moves down. This makes the space
inside the chest (the thoracic cavity) much bigger, air pressure
decreases inside creating a vacuum causing air to rush in via the
top end (nose and mouth), filing the lungs and all its parts,
ending in the alveoli… then the respiratory centre stops making
the muscles contract. This causes the muscles of the ribs and
diaphragm to relax.
The ribcage moving out and up, the diaphragm moving down,
creating the big space and the reduced pressure allows the air
to rush in….IN….Inspiration.
The Ribcage moving in and down, the diaphragm moving up
again, smaller space, bigger pressure…Expiration.
,Gas Exchange the different organs and tissues.
The blood reaches the narrow capillaries around the organs,
Exchange of gases between the lungs and the blood stream is RBCs release the O2; here it diffuses through capillary walls
called EXTERNAL respiration. into body tissues, known as INTERNAL respiration. CO2
diffuses from tissues into RBC and plasma. Deoxygenated blood
Oxygen needs to get into the blood stream and co2 needs to get is carried back to the lungs.
out of the blood stream. This takes place at the alveoli.
There are 3 things we need for adequate respiration both
In the lungs at the alveoli, o2 is exchanged for co2 via… external and internal,
external respiration.
O2 diffuses (moves from somewhere where its high in Ventilation, Diffusion and Perfusion.
concentration to somewhere where its low in concentration)
Ventilation is the process by which air moves in and out of the
from the alveoli, that’s just breathed in fresh gas, to the
lungs.
capillary that contains blood that’s has had all its 02 used up
around the body. It has come back to the lungs to pick up more. Diffusion is the spontaneous movement of gases, without the
use of any energy or effort by the body, between the gas in the
alveoli and the blood in the capillaries in the lungs. Moving from
a high concentration to a low concentration because the body
likes balance.
Perfusion is the process by which the cardiovascular system
pumps blood throughout the lungs.
A problem with any of the above will cause gas exchange to be
impaired. Known as a VQ mismatch.
V- ventilation-air that reaches alveoli
Imagine a road (blood vessel) with taxis (haemoglobin), the Q-perfusion- blood that reaches alveoli
taxi rank (the lungs), the taxi picks up a person (O2 molecule) You can have all the oxygen you need but if there’s no blood to
takes them to all the places they need to go, the pub the carry it =impaired gas exchange
shops, the school etc (kidneys, brain, liver etc) then it comes
back empty to Likewise you can have the best blood transport system in the
the taxi rank to land but if no oxygen arrives to be carried= gas exchange
pick up a new Impaired.
person/
passenger…. And
that first
passenger left
there drinks
carton and empty
crisp packet
(CO2 molecule) in
the taxi…. So the
taxi will put
them in the bin
back at base.
Q
Each alveolar lining is 1 cell in thickness, it’s a very small
membrane to pass through gas exchange happens very quickly.
Every alveolus is surrounded by a capillary. The co2 leaves the
capillary and enters the alveoli to be breathed out during So what might cause impairment in ventilation or perfusion?
exhalation. The o2 passes from the alveoli into the capillary, Ventilation: Perfusion:
-something wrong with the breathing -something wrong with the blood side
binds to haemoglobin in the red blood cells. From the capillary,
side Hypovolaemia, sepsis, bleeding, shock,
the oxygenated blood passes through the pulmonary veins and Infection or fluid in the alveoli preventing the blood getting to the
into the left side of the heart. The blood then leaves the heart decreasing the space for exchange lungs…… perfusion
Collapsed alveoli (atelectasis)
via the aorta to be pumped around the body using oxygen at all decreasing surface area….. Ventilation
,Respiratory Assessment Signs of tracheal deviation
Look for any; scars/wounds, look for chest symmetry are both
sides equal or does one side rise and the other doesn’t…
Airway assessment- indicative that one lung isn't moving therefore no air entry.
What is the position of the patient, are they slumped in the
“Hey how are you?” bed?
If they answer by talking, the airway is patent as air needs to Palpate:
pass over the vocal chords to produce a voice. Feel for the tracheal position in the middle
Breathing assessment- Feel for the chest expansion, does it feel the same on each side
or again is one side rising more than the other? (place hands on,
thumbs together... do they move apart)
And this is what we look for:
Percussion:
Inspect:
Between each rib, lay the middle finger of one hand and tap
Respiratory rate- how many times you breathe in a minute. with the opposite hands middle finger, what do you hear? What
is the percussion note?
Quite simply done by watching the chest rise and fall in 1 whole
minute and making a note of that number. Resonant-normal
Dullness- increased tissue density (consolidation, fluid, tumor,
A normal respiratory rate is about 12 to 20 breaths per
collapse)
minute, any less the patients not breathing enough, any more Stony dullness (pleural effusion)
the patient is breathing too much. Hyper resonance (airy like a drum, e.g. pneumothorax)
Breathing not enough -hypoventilation Auscultate::
Listen for the quality of breath sounds;
Breathing too much -hyperventilation
-Vesicular is normal
-Bronchial is harsh associated with consolidation
Skin colour- just look at your patient with your eyes. Look for
-Listen to the volume
central or peripheral cyanosis.
Quiet may indicate reduced air entry from, consolidation, collapse
or pleural effusion.
Use of Accessory muscles- tell us that our patient is struggling
-Are there any added sounds?
to breath. Normally if you watch a person breath, it’s a steady
Like a wheeze from asthma or COPD. Coarse crackles indicating
rise and fall of the chest. If you witness your patients fluid overload, pneumonia, bronchiectasis. Or a fine crackle from
breathing and their stomach is moving up and down or their pulmonary fibrosis.
neck is strained, there's something wrong, gas exchange is
impaired so they're using all their might to drag air in. Pulse oximetry- a peg on the finger with a red light inside
making a number up to 100% (the peg uses a type of light
Sputum assessment- colour, thickness, amount. Coughing is a source called “light emitting diodes” (LED), oxygenated
reflex to clear out the lungs, if our patients expectorate (cough haemoglobin will have a different
up sputum) there's a reason, the body's trying to get rid of light length than deoxygenated
something that shouldn’t be there. haemoglobin. The sats probe senses
Red/bloody- ? blood bleeding, Foamy white – may come the ones with the oxygen and
trauma, tumours ulcers in from earlier-phase pulmo- displays it as a percentage).
the respiratory tract. Is it nary oedema. Depending on the patients past
inflammation?
Frothy pink – may indicate medical history, we like the
Greenish- infection more severe pulmonary saturations to be above 94%,
oedema. however if the patient has a
Brownish – chronic bronchi-
tis greenish/yellowish/ Clear – pulmonary embolism pre-existing lung condition,
brown); chronic pneumonia (clear to frothy); COPD parameters may be variable for
(whitish-brown); tuberculo- chronic obstructive pulmo- example, anything above 89%.
sis; lung cancer. nary disease (clear to grey);
viral respiratory infection Investigations:
Yellow, yellowish purulent – (clear to whitish and some-
containing pus. Infection, or times a hint of yellow); XRAY
improving bronchitis. asthma (thick and white to
yellowish). Bloods- Hb, haematocrit, infection
A white, milky, or opaque
(mucoid) appearance likeli- Thick sputum can be an markers
hood is of a viral infection or indication of dehydration.
allergy (even asthma...thick Arterial Blood Gas analysis
sputum).
, Basic arterial blood gas With inadequate breathing comes a rise in CO2 which is an acid
and will upset the pH (respiratory acidosis). Hyperventilating
will cause a fall in CO2 causing a respiratory alkalosis. We need
analysis to treat a rise in CO2 by increasing the rate and depth of
breathing. And to treat a fall in CO2 we need the patient to
Arterial blood gas analysis is essential in diagnosing and slow down their breathing taking deeper breaths.
managing oxygen status and acid-base balance of critically ill
NB. If the pH moves in the opposite direction from the PaC02.
people. It is fast and accurate, aids in diagnosis, guides
i.e. the pH goes down while the PaC02 goes up… it’s a
treatment and aids in ventilator management
respiratory acidosis.
Normal ranges: 4. Next look at if there's any metabolic causes
pH: 7.35 – 7.45
Looking at HC03 or BE. Comparing with the pH. If they are
PaCO2: 4.7 – 6.0 kPa || 35.2 – 45 mmHg
moving in the same direction as the pH, imbalance is metabolic in
PaO2: 10 – 13 kPa || 82.5 – 97.5 mmHg
origin.
HCO3–: 22 – 26 mEq/L
Base excess (BE): -2 to +2 mmol/L HCO3 (bicarbonate) - >26 =metabolic alkalosis <22 = metabolic acidosis
Lactate: 0.5-2.5 mmol/L
HCO3 an (antacid) falls when it has been used up in the blood
to ‘buffer’ (clean up) acids. It also will fall if the kidneys fail and
Analysis: can no longer create HC03.
1. Look at the Pa02 Base excess (BE) – A high base excess is another marker of
metabolic acidosis or alkalosis. > +2mmol/L indicates that there
PaO2 (partial pressure of oxygen) -should be >10 kPa when
is a higher than normal amount of HCO3, due to metabolic
oxygenating on room air in a healthy patient.
alkalosis or a compensated respiratory acidosis. A low base
If the patient is receiving oxygen their PaO2 should be excess < -2mmol/L indicates a lower than normal HCO3, due to
about 10kPa less than the % inspired concentration FiO2 (so a primary metabolic acidosis or compensated respiratory alkalosis.
patient on 40% would be expected to have a PaO2 of
5. Finally, looking for compensation or mixed causes.
approximately 30kPa).
Compare the PaC02 with the HC03, if they both go in the
If Pa02 is low (hypoxaemia) we can give oxygen therapy.
same direction, one of them is compensating to help the other
2. Is the blood acidic or alkali? out (then we need to look at the clinical picture to determine
which). But if they move opposite in direction, then the acidosis
Blood pH is the acidity or alkalinity of blood. It is the measure or alkalosis is mixed, its both metabolic and respiratory in cause.
of hydrogen ion concentration. The lower the pH the more
hydrogen ions, the more acidic. The higher the pH, the less Respiratory compensation for a metabolic disorder can
hydrogen ions the more alkalotic occur quickly by either increasing or decreasing alveolar
ventilation to blow off more CO2 (↑ pH) or retain more CO2
Normal blood pH is regulated between 7.35-7.45 known as the (↓ pH).
acid/Base balance (Base being the alkali part).
Metabolic compensation for a respiratory disorder however,
Acid base balance is the body’s mechanism to keep body fluids takes at least a few days to occur as it requires the kidneys to
close to a normal (neutral) pH, so it can function normally known either reduce HCO3– production (to decrease pH) or increase
as homeostasis. HCO3– production (to increase pH). As a result, if you see
Homeostasis- refers to the body’s ability to maintain a stable evidence of metabolic compensation for a respiratory disorder
internal environment despite external condition changes. As (e.g. increased HCO3-/base excess in a patient with COPD and
conditions change, the body compensates to maintain uniform CO2 retention) you can assume that the respiratory
conditions. Cells of the body will only survive outside of the derangement has been ongoing for at least a few days, if not
normal range of pH for a short time (hours). But pH <6.9 or more.
>7.8 survival is unlikely.
Other values:
After looking at pH and determining acidosis or alkalosis we need
to determine whether its respiratory or metabolic in cause. To Lactate– Rising lactate will indicate lack of oxygen in cells
determine this we look at CO2 and HCO3 Haematocrit (Hct)- The proportion of red blood cells in the
blood, it can help to be able to see how dilute your patient
3. Is pH imbalance due to respiratory causes?
is
PaCO2- >6.0 =acidosis <4.7 =alkalosis Various electrolytes
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