Makindo Medical Notes.com

Related Subjects: Atropine |Acute Anaphylaxis |Basic Life Support |Advanced Life Support |Adrenaline/Epinephrine |Acute Hypotension |Cardiogenic shock |Distributive Shock |Hypovolaemic or Haemorrhagic Shock |Obstructive Shock |Septic Shock and Sepsis |Shock (General Assessment) |Toxic Shock Syndrome |Non invasive ventilation (NIV) |Intubation and Mechanical Ventilation |Critical illness neuromuscular weakness |Multiple Organ Dysfunction Syndrome

In acute coronary syndromes PCI, thrombolysis, or other interventions may be needed. Patients and their myocardium can be instantly revived when the coronary artery reperfuses

About

• This is a peri-arrest perilous state and demands rapid action and senior help if an active approach is indicated
• The primary problem is cardiac output. The question is why
• A simple bedside echo to exclude tamponade, access LV and valves is invaluable
• ST elevation or new LBBB demands reperfusion strategy - Primary PCI preferred

Introduction

• Shock is not a diagnosis but a clinical syndrome of organ hypoperfusion
• Cardiogenic shock is when the aetiology is primarily cardiac
• Shock makes shock worse ! There is an inexorable decline unless urgent remedial intervention
• Make sure it is not misdiagnosed RV infarction needing filling or a tamponade needing draining

Causes

• Myocardial disease
  • ischaemic cardiomyopathy
  • Myocardial infarction - classically Anterior STEMI or NSTEMI
  • Myocarditis
  • Cardiomyopathy 
• Valve failure
  • Endocarditis
  • Acute MR
  • Acute VSD
  • Aortic regurgitation
• Toxins
  • Verapamil overdose
  • Excess Beta blocker and other negative inotropes
• Congenital heart disease
  • Neonates and infants
• Arrhythmias
  • Ventricular tachycardia
  • Fast Atrial fibrillation
  • Heart block

Stages

Clinical

• Hypotension BP < 90/60 mmHg, poor thready central pulse, cold peripheries, obtunded
• AF, Dependent Oedema and Dyspnoea
• Raised JVP which may rise in Inspiration - Kussmaul's sign
• S3, Ascites , ankle oedema, hepatomegaly
• Tension PTX : reduced breath sounds, Resonant, trachea shifted away
• Tamponade: Raised JVP, faint heart sounds, globular heart on CXR, small complexes on ECG

Investigations

• FBC : treat anaemia Hb < 90 g/L Transfuse slowly with diuretics
• U&E: ↑ Creatinine ↑ K ↑ lactate
• LFTs: ↑ AST with hepatic ischaemia
• ECG - may be low voltage, ST elevation, new LBBB, True posterior MI
• Urgent Echo - LV dysfunction, assess valve integrity. Discuss with on call cardiologist.
• ABG: hypoxia, acidosis
• CT / MRI are useful to exclude constrictive pericarditis

Management:

• Mortality is about 70% unless there is any easily remedial treatable cause eg Large MI and angioplasty and reestablishment of coronary perfusion
• Oxygen 15 l/min if non-COPD otherwise 28-35% and reassess after ABG
• Chest pain and ST elevation should receive Diamorphine 2.5-5 mg slow IV or Morphine 2.5-5 mg slow IV and STEMI protocol referring Primary PCI and urgent thrombolysis is PCI not possible
• Arrhythmias management - If fast AF then (and not on Digoxin) then give Digoxin 500 mcg stat slow iv infusion or consider Amiodarone 300 mg over 1 hour by a large bore or central cannula. Beware of other antiarrhythmics as most are negatively inotropic. Amiodarone as described for VT. If there is no rapid improvement with any tachyarrhythmia then synchronised DC cardioversion. Anticoagulate after if indicated. Summon anaesthetic help.
• Look for a globular heart on CXR. Get an urgent echocardiogram which will usually involve cardiologists. Needle pericardiocentesis for a tamponade. Traditionally needle with 3 ways tap for fluid drainage inserted to the left of the xiphisternum and directed towards the left shoulder constantly aspirating. Need ECG monitoring and defibrillator standing by. Aspirate fluid in the pericardial space. If stabilised talk to cardiac surgeons.
• A central line or even more useful a Swan-Ganz may be useful if it can be placed quickly and without worsening the perilous state of the patient. Placing a patient's head down for 30 minutes in an open busy ward with an agitated hypoxic patient does not often improve the outcome or necessarily add value. If it can be done slickly by an experienced operator and aseptically then consider it. Best done on the HDU or in a dedicated area on the CCU and by those who are experienced at monitoring. It is important not just to be guided solely by the pulmonary wedge pressure (equivalent to left atrial filling pressure) when other evidence contradicts. A value under 15 mmHg suggests a fluid challenge.
• Urinary catheter is useful to give a very surrogate measure of cardiac output and renal perfusion.
• If there is a suggestion of hypovolaemia then a fluid challenge may be useful. Pulmonary embolism and RV infarction can benefit from some additional filling. The skill is a frequent reassessment of all physiology. Plasma expander 100 ml aliquots given over 10-15 mins and reassess.
• Renal dose Dopamine 2-5 mcg/kg/min iv but there is no evidence base for this.
• Inotrope: The drug of first choice is adrenaline (short term) as it has inotropic and vasoconstrictor effects, the latter predominating at higher doses. An arterial line should be used to monitor BP. Adrenaline should be infused via a central venous catheter
• Intraaortic balloon pumping can greatly improve cardiac output and is useful as a bridge to revascularisation or valve repair. It is however not indicated for acute aortic regurgitation. See article. An Intra-aortic balloon pump (IABP) is inserted via the femoral artery and advanced to just below the aortic arch at the branch of the left subclavian artery. The balloon is set up to inflate with diastole and deflate with systole. This improves cerebral and coronary perfusion. Remember most coronary perfusion is in the diastole.