Anaesthesia - Critical Care Flashcards
What is critical care?
The patient care for those suffering from organ failure
Where do we treat patients with single organ failure?
High dependency units
Where do we treat patients with multiple organ failure?
Intensive care units
What is respiratory failure?
A condition in which the respiratory system fails to maintain its main function, gas exchange
What is the clinical definition of respiratory failure?
PaO2 lower than 60mmHg
and/or
PaCO2 greater than 50mmHg
What is 60mmHg in kPa?
8 kPa
What is 50mmHg in kPa?
6.7 kPa
What are the two types of respiratory failure?
Respiratory Failure Type One
Respiratory Failure Type Two
What is type one respiratory failure?
It is defined as a PaO2 lower than 60mmHg with normal PaCO2
It is therefore oxygenation failure
Describe the pathophysiology behind type one respiratory failure
It occurs as a result of damage to lung tissue
This prevents adequate oxygenation of the blood; however, the remaining normal lung is still sufficient to excrete the carbon dioxide being produced
This is due to the fact that less functioning lung tissue is required for carbon dioxide excreter than is needed for oxygenation of the blood
Name four respiratory conditions associated with type one respiratory failure
Pulmonary Oedema
Pneumonia
Acute Respiratory Distress Syndrome
Chronic Pulmonary Fibrosing Alveolitis
What is type two respiratory failure?
It is defined as a PaO2 lower than 60mmHg with PaCO2 greater than 50mmHg
It is therefore oxygenation and ventilation failure
Describe the pathophysiology behind type two respiratory failure
It occurs as a result of reduced ventilatory effort resulting in the accumulation of carbon dioxide
Name five respiratory conditions associated with type two respiratory failure
COPD
Asthma
Guillain-Barre Syndrome
Cerebrovascular Disease
Opiate Overdose
What are six clinical features associated with respiratory failure?
Dyspnoea
Tachypnoea
Confusion
Tachycardia
Central Cyanosis
Pulmonary Hypertension
What are the three investigations used to diagnose respiratory failure?
Blood Tests
Arterial Blood Gas
Pulmonary Function Tests
Which two blood tests are used to diagnose respiratory failure? Why?
LFTs
U&Es
It may indicate the underlying cause of respiratory failure and identify any complications associated with it
How are arterial blood gases used to diagnose respiratory failure?
It measure oxygen and carbon dioxide levels
What are pulmonary function tests?
They are non-invasive tests that show how well the lungs are working
They specifically measure lung volume, capacity, rates of flow and gas exchange
How are pulmonary function tests used to diagnose respiratory failure?
They allow the underlying cause of respiratory failure to be identified
What does a normal FEV1 & FVC level indicate the underlying cause of respiratory failure is?
There are defects in respiratory control
What does a reduced FEV1: FVC level indicate the underlying cause of respiratory failure is?
Airflow obstruction
What does a decreased FEV1 & FVC level indicate the underlying cause of respiratory failure is?
Restrictive lung disease
In what two ways do we manage respiratory failure?
Oxygen Replacement Therapy
Ventilatory Support
What is the function of oxygen replacement therapy?
To maintain adequate tissue oxygenation
What PaO2 level and saturation level indicate adequate tissue oxygenation?
PaO2 - 60mmHg
Saturation - 90%
What respiratory failure classification is treated with oxygen therapy? How
Type one respiratory failure
It corrects hypoxemia
What are three forms of oxygen therapy?
Nasal Cannula
Hudson Face Mask
Non-Rebreather Face Mask
What percentage of oxygen is contained in room air?
21%
What percentage of oxygen is delivered by a nasal cannula?
30%
At what rate does a nasal cannula deliver oxygen?
2 - 4L per minute
What percentage of oxygen is delivered by a high flow nasal cannula?
40 - 60%
At what rate does a high flow nasal cannula deliver oxygen?
4 - 10L per minute
What percentage of oxygen is delivered by a Hudson face mask?
100%
At what rate does a Hudson face mask deliver oxygen?
60L per minute
What percentage of oxygen is delivered by a non-rebreather face mask?
60-80%
At what rate does a non-rebreather face mask deliver oxygen?
10-15L per minute
What are the mechanisms in which ventilation can be supported?
Non-Invasive Respiratory Support
Invasive Respiratory Support
What is non-invasive respiratory support?
It is ventilatory support via a face mask – without tracheal intubation
How does a non-invasive respiratory support work?
It applies pressure to the patients’ airways, thus maintaining patency and reducing their work of breathing
What type of respiratory failure is treated with non-invasive respiratory support?
Mild to moderate type two respiratory failure, particularly those affected with associated COPD
What is invasive respiratory support?
It is ventilatory support via endotracheal tube intubation
What is an endotracheal tube?
An endotracheal tube is a plastic tube that is inserted through the mouth into the trachea
It is then connected to a ventilator, which delivers oxygen to the lungs
How does invasive respiratory support work?
The endotracheal tube consists of an air-inflated balloon, which forms a seal in the patient’s upper airways
This allows all gas to enter straight into the patient’s lungs and providing protection to the airway
What type of respiratory failure is treated with invasive respiratory support?
Severe type two respiratory failure, particularly those with persistent hypoxemia despite receiving maximum oxygen therapy and hypercapnia with impairment of conscious level
What are the four complications of respiratory failure?
Nosocomial Pneumonia
Heart Failure
Arrythmia
Pericarditis
What is acute heart failure?
It is a condition in which the cardiovascular system fails to pump sufficient quantities of blood to meet the physiological demands of the body
This causes a backflow of blood, resulting in increased blood volumes in the left atrium, pulmonary veins and lungs.
What are the two classifications of acute heart failure?
Systolic Heart Failure (HFrEF)
Diastolic Heart Failure (HFpEF)
What is systolic heart failure?
It is inability of the ventricle to contract normally
How is the cardiac output and ejection fraction affected by systolic heart failure?
CO - decreased
Ejection fraction - <40%
What are the four causes of systolic heart failure?
Ischaemic heart disease
Dilated cardiomyopathy
Myocarditis
Arrhythmias
What is diastolic heart failure?
It is inability of the ventricle to relax normally, resulting in decreased volumes of blood filling the ventricles
How is ejection fraction affected by diastolic heart failure?
Ejection fraction - > 50%
What is diastolic heart failure progress into?
It commonly progresses into systolic heart failure
What are the four causes of diastolic heart failure?
Hypertrophic obstructive cardiomyopathy
Restrictive cardiomyopathy
Cardiac tamponade
Constrictive pericarditis
What is high output heart failure?
This refers to a situation where a ‘normal’ heart is unable to pump enough blood to meet the metabolic needs of the body
What are the five causes of high output heart failure?
Anaemia
Paget’s disease
Pregnancy
Thyrotoxicosis
Thiamine deficiency
What two drugs cause heart failure?
Verapamil
Diltiazem
What is the most common cause of heart failure?
Ischaemic heart disease
What are the six symptoms of acute heart failure?
Dyspnoea on Exertion
Cough with White/Pink Sputum
Orthopnoea
Paroxysmal Nocturnal Dyspnoea
Peripheral Oedema
Ascites
What are the five signs of acute heart failure on examination?
Tachycardia
Tachypnoea
3rd Heart Sound
Bilateral Basal Cracks
Increased JVP
What two clinical features indicate right sided heart failure?
Increased JVP
Peripheral oedema
What scoring system is used to diagnose acute heart failure?
Framingham Criteria for Congestive Heart Failure
What ‘Framingham Criteria for Congestive Heart Failure’ score indicates a diagnosis of heart failure?
2 major criteria
OR
1 major criterion and 2 minor criteria
What are the five major criteria of the ‘Framingham Criteria for Congestive Heart Failure’ ?
PAINS
Paroxysmal Nocturnal Dyspnoea
Acute Pulmonary Oedema
Increased Heart Size/
Increased Central Venous Pressure
Neck Vein Dilatation
S3 Gallop
What are the four minor criteria of the ‘Framingham Criteria for Congestive Heart Failure’ ?
PAIN
Pleural Effusion
Ankle Oedema (Bilateral)
Increased Heart Rate, which is greater than 120bpm
Nocturnal Cough
What are the three investigations used to diagnose acute heart failure?
Blood Tests
Echocardiogram (ECHO)
Chest X-Ray (CXR)
What two blood tests are used to diagnose heart failure?
BNP blood test
Sodium
What is BNP?
A hormone that is released from the heart ventricles when the myocardium is stretched beyond normal range
What is the function of BNP?
It relaxes the smooth muscles in blood vessels, which reduces the systemic vascular resistance and makes it easier for the heart to pump blood
It acts on the kidneys to promote the excretion of water in urine, which reduces circulating volume and improves cardiac function
What BNP result indicates heart failure? Why?
Elevated
This indicates that the heart is overloaded beyond its normal capacity to pump effectively
What investigation is conducted after a high BNP result to confirm heart failure?
ECHO
What sodium level indicates heart failure?
Decreased
What do ECHO scans assess?
They are used to assess cardiac function, allowing measurement of the LV ejection fraction
What is the LV ejection fraction?
This is the percentage of blood in the ventricle that is pumped out with each ventricular contraction
What is a normal LV ejection fraction?
50-80%
What LV ejection fraction indicates mild HF?
40-50%
What LV ejection fraction indicates moderate HF?
30-40%
What LV ejection fraction indicates severe HF?
< 30%
What five signs indicate heart failure on a CXR?
Alveolar Oedema
Kerley B Lines
Cardiomegaly
Dilated Upper Lobe Vessels
Pleural Effusion
What are the two ways in which we manage heart failure conservatively?
We advise patients to sit upright
We administer oxygen in patients with saturation level less than 95%
Why do we advise heart failure patients to sit upright?
This is due to the fact that when lying flat, the fluid in the lung’s spreads to larger area
However, when sitting upright, gravity results in the movement of fluid to the base of the lung, leaving the upper lungs clear for gas exchange
In which patients do we take caution in administrating oxygen to?
COPD patients
What are the three pharmacological management options for heart failure?
Diuretics
Vasopressors
Inotropes
What diuretic is used to treat heart failure?
Furosemide
How do diuretics work to treat heart failure?
They reduce the circulating volume and therefore allow the heart to pump more effectively
What two vasopressors are used to treat heart failure?
Metaraminol
Noradrenaline
What is the first line vasopressor drug?
Noradrenaline
How do vasopressors work to treat heart failure?
They are drugs involved in the contraction of blood vessels to raise blood pressure
They improve cardiac function by reducing preload and increasing afterload
What two inotropes are used to treat heart failure?
Adrenaline
Dobutamine
How do inotropes work to treat heart failure?
They are drugs that strengthen the force of heart contractions
When do we administer inotropes for heart failure?
They are only administered in high dependency and intensive care units
This is because they require close monitoring
What drug is contraindicated in heart failure?
Pioglitazone
How do we proceed if pharmacological management of acute heart failure fails?
CPAP
What is an arterial line?
It is a catheter inserted into an artery
What are the two functions of an arterial line?
Blood pressure measurement
To allow regular blood sampling
What is a central line?
It s a catheter inserted into a central vein
What four veins are used for central lines?
IJV
Subclavian vein
Axillary vein
Femoral vein
What are the two functions of central lines?
To allow the administration of highly potent drugs directly into central circulation
To allow regular blood sampling
What are the two main classifications of fluid resuscitation products?
Colloid
Crystalloid
What are colloids?
They are solutions that consist of large osmotically active molecules
List five colloid fluid examples
Albumin
Dextran,
Hydroxyethyl starch
Haemaccel
Gelofusine
What are crystalloids?
They are solutions that consist of small osmotically active molecules
List five crystalloid fluid examples
Plasmalyte 148
0.9% saline sodium chloride
Packed red cells
Hartmann’s solution
5% dextrose solution
What is more commonly prescribed - colloid, crystalloid?
Crystalloid
What is the first line fluid used in resuscitation?
Plasmalyte 148
What volume of fluid is given in healthy patients at one time?
500mls
What volume of fluid is given at one time in individuals at increased risk of fluid overload, such as those with chronic heart failure, etc?
250mls
When is a referral advised during fluid resuscitation?
In cases where 30ml/kg doesn’t relieve fluid resuscitation