Acute LVF and Pulmonary oedema Flashcards
Pathophysiology of acute LVF + pulmonary oedema?
Left ventricle is unable to adequately move blood through the left side of the heart and out into the body
Causes a backlog of blood that increases the amount of blood stuck in the left atrium, pulmonary veins and lungs
As the vessels in these areas are engorged with blood due to the increased volume and pressure they are unable to reabsorb fluid from the surrounding tissues - causes pulmonary oedema
Lung tissues and alveoli become full of interstitial fluid
Interferes with the normal gas exchange in the lungs, causing SOB, oxygen desaturation and other signs and symptoms
Risk factors for Acute LFV
Iatrogenic !! (eg aggressive IV fluid in frail elderly patients with impaired left ventricular function)
Sepsis
MI
Arrhythmias
Acute LVF typically presents with?
Rapid onset breathlessness
Exacerbated by lying flat and improves on sitting up
Acute LVF causes a type 1 respiratory failure (low oxygen without an increase in CO2 in the blood)
Symptoms of acute LVF and pulmonary oedema?
- Shortness of breath
- Looking and feeling unwell
- Cough (frothy white/pink sputum)
Examination findings with acute LVF and pulmonary oedema?
- Increase respiratory rate
- Reduced oxygen saturations
- Tachycardia
- 3rdHeart Sound
- Bilateral basal crackles (sounding “wet”) on auscultation
- Hypotension in severe cases (cardiogenic shock)
There may also be signs and symptoms related tounderlying cause, for example:
- Chest pain in ACS
- Fever in sepsis
- Palpitations in arrhythmias
If they also haveright sided heart failureyou could find:
- RaisedJugular Venous Pressure (JVP)(a backlog on the right side of the heart leading to an engorged jugular vein in the neck)
- Peripheral oedema (ankles, legs, sacrum)
TIP: When you are on the wards and a nurse asks you to review a patient that has just started desaturating ask yourself how much fluid that patient has been given and whether they might not be able to process that much. For example, an 85 year old lady with chronic kidney disease and aortic stenosis is prescribed 2 litres of fluid over 4 hours and then starts to drop her oxygen saturations. This is a common scenario and a dose of IV furosemide can often work like magic to clear some fluid and ease their breathing.
tom tip
Investigations for acute LVF?
- History
- Clinical Examination
- ECG (to look for ischaemia and arrhythmias)
- Arterial Blood Gas (ABG)
- Chest Xray
- Bloods (routine bloods for infection, kidney function,BNPand considertroponinif suspecting MI)
If the clinical presentation is acute LVF then treat before having the diagnosis confirmed by BNP or echo. Without treatment they can deteriorate before getting the investigations.
BNP blood test will show?
B-type Natriuretic Peptide (BNP)is a hormone that is released from the heartventricleswhen the cardiac muscle (myocardium) is stretched beyond the normal range. Finding a high result indicates the heart is overloaded (with blood) beyond its normal capacity to pump effectively.
The action of BNP is to relax the smooth muscle in blood vessels. This reduces thesystemic vascular resistancemaking it easier for the heart to pump blood through the system. BNP also acts on the kidneys as a diuretic to promote the excretion of more water in the urine. This reduces the circulating volume helping to improve the function of the heart.
Testing for BNP issensitive but notspecific.This means that when negative it is useful inruling outheart failure, but when positive result can have other causes. Other causes of a raised BNP include:
- Tachycardia
- Sepsis
- Pulmonary embolism
- Renal impairment
- COPD
Echocardiography (echo) will show?
This is useful in assessing the function of the left ventricle and any structural abnormalities in the heart. The main measure of the left ventricular function is theejection fraction.
This is the percentage of the blood in the left ventricle is squeezed out with eachventricular contraction, An ejection fractionabove 50% is considered normal.
Chest xray findings include?
Cardiomegaly on a chest xray is defined as acardiothoracic ratioofmore than 0.5. This is when the diameter of the widest part of the heart (the wides part of thecardiac silhouette) is more than half the diameter of the widest part of thelung fields.
Upper lobevenous diversion. Usually when standing erect the lower lobe veins contain more blood and the upper lobe veins remain relatively small. In LVF there is such a back-pressure that the upper lobe veins also fill with blood and become engorged (referred to asupper lobe diversion). This is visible as increased prominence and diameter of the upper lobe vessels on a chest xray.
Fluid leaking from oedematous lung tissue causes additional xray findings of:
- Bilateralpleural effusions
- Fluid ininterlobar fissures
- Fluid in the septal lines (Kerley lines*)
mnemonic for acute LVF treatment?
Pour SOD
Pour away (stop) their IV fluids
Sit up
Oxygen
Diuretics
Sit the patient upright. When lying flat the fluid in the lungs spreads to a larger area. When upright gravity takes it to the bases leaving the upper lungs clear for better gas exchange.
Oxygen if their oxygen saturations are falling (<95%). As always be cautious in patients with COPD.
Diuretics(e.g. IVfurosemide40mg stat). This reduces the circulating volume and means the heart is less overloaded allowing it to pump more effectively. This is like taking your backpack off when on a hike – it allows you to walk more easily.
Monitor fluid balance.Measuring fluid intake, urine output, U&E bloods and daily body weight is essential to balance their fluid input and output.
Other options apart from Pour SOD to consider in severe acute pulmonary oedema or cardiogenic shock (not routinely used) include?
IV opiates (eg morphine, act as vasodilators but are not routinely recommended)
Non-invasive ventilation (NIV). Continuous Positive Airway Pressure (CPAP) - involves using a tight fitting mask to forcefully blow air into their lungs. this helps to open the airways and alveoli to improve gas exchange. if NIV does not work they may beed full intubation and ventilation.
“inotropes” for example NA. inotropes strengthen the force of heart contractions and improve heart failure, however they need close titration and monitoring, so by this point you would need to send the patient to the local coronary care unit/high dependency unit/ICU.
