W2 Respiratory Flashcards
- Respiration:
gas exchange between the atmospheric air and the blood and between the blood and the cells of the body.
- Ventilation:
the movement of air, in and out the lungs. (Normal alveolar ventilation 4L/min)
- Perfusion:
is the blood that flows through the vascular system, delivering oxygen and nutrients to organs and tissues. Pulmonary perfusion is blood that flows through the pulmonary vasculature, reaching the alveoli for the transfer of gases. (Norm cap perfusion 5/min. V/Q ratio = 0.8
- Diffusion:
the exchange of gas molecules from areas of high concentration to low concentration.
- Dead space:
is the space of the brachial tree that does not participate in gas exchange due to a high volume of gas and under perfusion. Alveolar dead space the area in the lungs that is under perfused and does not participate in gas exchange. Can be impacted by positioning, respiratory diseases (Emphysema), Positive airway pressure (CPAP), PE, Hypotension.
- Orthopnoea:
increased WOB when lying down.
- Non Invasive ventilation:
Delivers positive pressure breaths to a spontaneously breathing patient, increasing the patient’s breath size via a non-invasive device.
- Invasive mechanical ventilation:
The patient is assisted to breathe by an artificial airway which is connected to a mechanical device, which is used to assist or replace spontaneous breathing. Used on patients who are unable to maintain own airway (absent gag reflex, GCS), inadequate breathing rate/pattern and inability to sustain bodies oxygen demands with supplemental oxygen. (Respiratory failure, acute lung injury, asthma, COPD, pneumothorax, PE, pneumonia, acute respiratory distress syndrome).
Continuous Positive Airway Pressure:
CPAP is a type of ventilator support for spontaneously breathing patients. CPAP reduces the work of breath on inspiration, promoting gas exchange by reducing hypoxia. CPAP can be delivered through non-invasive or addition to invasive ventilation. Commonly used for Pulmonary Oedema, atelectasis, COPD, asthma, apnoea, respiratory failure type 1)
- Bi level Positive Airway Pressure
BiPAP involves two levels of positive airway pressures. A higher pressure is delivered on inspiration and lower pressure on expiration, ideally controlling lung expansion. Commonly used when CPAP not tolerated, COPD & Asthma to eliminate Co2, obstructive sleep apnoea, neurologic/neuromuscular disorders, weening off mechanical ventilation.
Normal ABG Ranges
pH:
Pco2:
HCO3:
pH: 7.35-7.45 (Acid < > Base)
Pco2: 35- 45 (Base < > Acid)
HCO3: 22- 26 (Acid < > Base)
What causes respiratory acidosis?
1) Alveolar hypoventilation- insufficient ventilation leading to hypercapnia. (Lower respiratory tract infections, ARDS, acute lung injury, neuromuscular disorder, respiratory failure).
2) Alveolar hyperventilation- (Anxiety, stress, DKA, COPD, asthma, pain).
3) Mechanical ventilation inadequate- under or over ventilate
4) Inadequate perfusion- as a result of hypovolaemia, PE, heart failure
How does the body compensate for Respiratory Acidosis? (signs)
o Rate and Depth of breathing increases- (breath of the excess Co2)
o Use of accessory muscles
o Increased heart rate (increase blood flow to the lungs)
o Vasoconstriction (depending on cause/shunts blood away from the under ventilated lung region)
o Patient cyanotic, confused, anxious, lethargy/sleepy.
Define Respiratory failure:
• ARF is a syndrome in which the respiratory system fails to carry out adequate gas exchange. This can involve one or both of the gases, oxygenation or/and carbon dioxide expulsion.
Characteristics of Type 1 Respiratory failure and what is it caused by?
(Hypoxaemic)
- Characterised by low oxygen levels in blood with no increase in Pco2
- Low/normal PCo2 levels
- Mismatch between ventilation and perfusion
- Causes: pneumonia, pulmonary oedema, atelectasis, acute lung injury
Characteristics of Type 2 Respiratory failure and what is it caused by?
(hypoxaemic/Hypercapnic)
- Characterised by high PaCo2 and low oxygen levels in blood
- Causes: alveolar hypoventilation (inadequate gas exchange), COPD, asthma, apnoea, acute lung injury, neuromuscular disorders (decreased respiratory drive).
what are the clinical manifestations of respiratory failure?
Patients often present
1) tachypneic, shallow breathing/small tidal volume,
2) tachycardic
3) confused/ anxious
4) Cool and clammy
5) cyanotic
what assessment would are required when a patient presents with respiratory failure?
- A-D assessment
- Respiratory rate and pattern (pursed lip breathing)
- Tidal volume
- Skin colour (cyanosis)
- GCS
A patient presents with clinical manifestations of Respiratory failure. what diagnostic testing would you is required?
- Continuous monitoring of oxygen saturation (pulse oximetry and ABGs)
- Chest X ray,
- Capnography (end tidal co2 monitoring)
- Microbiological cultures
- Monitor patient’s response to supplemental oxygen/ventilator support
(Titration of respiratory support is guided by patient comfort and compliance to ventilator mode, ABG, SPo2)
What nursing care is required for a patient with Respiratory Failure?
Treat primary cause
Maintaining adequate gas exchange through Oxygen support, CPAP, and BiPAP
Preventing complications of mechanical ventilation
what are the complications of Mechanical Ventilation and how can nurses prevent this?
o VAP → Oral care, peptic ulcer prophylaxis, positioning, subglottic suctioning, early weening.
o Alveolar rupture/pneumothorax → Careful monitoring of tidal volume and airway pressure
o Dislodgment, disconnection, leaks → ensure secure, cuff pressure assessment, circuit checks
o Injury from inadequate heat/moisture → Humidified oxygen to keep airway moist.
o Decreased cardiac output (due to increased venous resistance/intravascular pressure)
o Oxygen toxicity → close monitoring of oxygen saturation
What is the oxyhaemoglobin dissociation curve
describes the relationship between available oxygen and oxygen bind to haemoglobin
what does a shift to the left on the oxyhaemoglobin dissociation curve indicate?
Increased Infinity for Oxygen (Hb binds to O2 more readily) 1. Increased pH (alkalotic) 2. Low Co2 3. Low temperature Eg. Hypothermic state uses more oxygen
what does a shift to the right on the oxyhaemoglobin dissociation curve indicate?
Decreased Infinity for Oxygen (Hb releases O2 more readily),
1. Decreased pH
2. Increased Co2
3. Increased Temperature
Eg. Increased lactic acid released from tissues during exercise, infection, fever
Describe what is meant by the oxygen cascade?
- Describes the process of declining oxygen tension from the atmosphere to the cellular level/mitochondria. Oxygen has a partial pressure which is determined by the prevailing environment. Oxygen makes up 21% of inspired air and at the beginning of insertion has a partial pressure of 160mmHg. As oxygen moves down the respiratory tract, Po2 decreased due to residual air/fluid/pus in the lungs and by the time it reaches the alveolar, Po2 is 100mmHg. Because the pressure of oxygen in pulmonary arterial blood supply is lower being Po2 40mmHg, there is a transfer of oxygen across the alveolar membrane into the blood where there is a low o2 concentration, commonly known as diffusion. Oxygen binds to haemoglobin and travels to the tissues which have a P02 40mmHg and the same diffusion process occurs.
Factors that influence the transfer of oxygen from the alveolar to the blood stream:
ventilation perfusion mismatch, increased dead space, right to left shunt (cardiac shunt that allows blood to flow from the right side to the left side without being oxygenated, decreased cardiac output
Factors that influence the amount of oxygen in the blood stream:
oxygen carrying capacity of the haemoglobin, percentage of haemoglobin saturated, cardiac output
