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Slide 2 Dr Bronwyn Avard, July 2010 Slide 3 To understand the basic physiology of shock To understand the pharmacodynamics and pharmacokinetics of vasoactive drugs used in ICU To know the indications for the administration of different inotropes and vasopressors in the critically ill patient To know the complications of administering these vasoactive drugs, and relevant patient care issues Slide 4 Please complete pre-test before progressing with learning package. Click on this link : http://www.surveymonkey.com/s/vasoactivepretest Slide 5 SHOCK Slide 6 Cardiac output = stroke volume x heart rate amount of blood ejected from the ventricle in systole depends on : - preload - afterload - contractility Slide 7 Cardiac output = stroke volume x heart rate Preload = end-diastolic ventricular volume Afterload = resistance against which ventricle contracting Contractility = strength of muscle activity Cardiac index = cardiac output / BSA Slide 8 Oxygen delivery = cardiac output x arterial oxygen content stroke volume x heart rate preload afterload contractility [haemoglobin] x SaO 2 Slide 9 Blood pressure = cardiac output x systemic vascular resistance Slide 10 Slide 11 Hypovolaemic Cardiogenic Distributive / vasodilatory Obstructive Slide 12 Slide 13 Inotropes Vasopressors Slide 14 global oxygen delivery cardiac output arterial oxygen content mean arterial pressure cardiac output systemic vascular resistance Slide 15 Slide 16 Adrenaline Noradrenaline Dobutamine (Dopamine) Metaraminol Phenylephrine Ephedrine Slide 17 aka ephinephrine Low dose = heart rate & contractility High dose = vasoconstriction Slide 18 Adrenaline infusion 0.01mcg/kg/minute HR 110 bpm MAP 70mmHg Warm peripherally Infusion increases to 0.03mcg/kg/minute HR now 150bpm MAP now 65mmHg Cool peripherally WHY? Slide 19 As heart rate rises, less time available for cardiac filling, hence stroke rate falls MAP falls rather than rising as you would have expected Slide 20 aka norepinephrine Low doses = mainly HR & SV High doses = mainly vasoconstriction Slide 21 Nordrenaline infusion 0.05mcg/kg/minute MAP 55mmHg Warm peripherally As infusion increases Cool peripherally Lactate rising WHY? Slide 22 Vasoconstriction caused by higher dose noradrenaline redistributes blood flow to essential organs Even though MAP rises, splanchnic perfusion falls & rising lactate can indicate gut ischaemia Slide 23 Acts on both beta 1 and 2 receptors Net effects are Increased contractility Increased heart rate Mild vasodilation Effect on MAP variable and not always predictable may increase or decrease Slide 24 76 year old woman post NSTEMI HR 84bpm MAP 64mmHg Cool peripherally Begun on dobutamine 7.5mcg/kg/minute MAP falls to 60mmHg WHAT WOULD YOU DO? Slide 25 She was probably vasoconstricted prior to infusion. Beginning dobutamine caused vasodilatation hence MAP fell. Fluid bolus or noradrenaline would be appropriate. Slide 26 mcg/kg/min = rate (mL/h) x concentration (mcg/mL) weight (kg) x 60 Slide 27 mcg/kg/min = rate (mL/h) x concentration (mcg/mL) Weight (kg) x 60 You are caring for a 60 year old man, weighing approximately 90kg, admitted after a non-ST elevation myocardial infarction. He is receiving adrenaline at 5mL/h. The 100mL bag has 8mg adrenaline in it. What dose of adrenaline is he receiving ? (in mcg/kg/min) Slide 28 ANSWER : 0.07 mcg/kg/min Slide 29 mcg/kg/min = rate (mL/h) x concentration (mcg/mL) weight (kg) x 60 mcg/min = concentration (mg/mL) x 1000 x rate (ml/h) 60 Slide 30 mcg/min = concentration (mg/mL) x 1000 x rate (mL/h) 60 You are looking after a 25 year old woman who has been admitted with sepsis. She has 6mg noradrenaline in 100mL bag of normal saline, which is running at 5mL/hour. How many mcg/minute is she receiving? Slide 31 ANSWER : 5mcg/min This is why we use the concentration of 6mg/100mL as the mL/h equals mcg/min (she was on 5mL/h noradrenaline) Slide 32 Adrenaline Noradrenaline Ephedrine Metaraminol Phenylephrine Slide 33 Inotropes : Milrinone Levosimenden Vasopressor : Vasopressin Slide 34 Slide 35 Accurate measurement of vital signs & invasive blood pressure Check vasoactive drugs at start of shift Ideally administered centrally Labelling critical Change bag every 24 hours Slide 36 Local necrosis with extravasation Tachycardia & arrhythmias Increased myocardial oxygen consumption Ischaemia of gut &/or extremities Slide 37 Slide 38 Slide 39 Click on this link to complete the post-test : http://www.surveymonkey.com/s/vasoactiveposttest Slide 40