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Acute Care_
Cardiovascular
Question | Answer |
---|---|
what is CO? | CO is the product of heart rate and stroke volume. CO (ml/min) = HR (beats/min) x SV (mls) |
what is SV determined by? | Preload that depends on Ventricular end diastolic volume and is govetrnd by the vo and pressure of blood returning to heart |
what are the common causes of inadequate ventricular preload? | hemorrhage, sepsis, anaphylaxix, raised intrathoracic pressure (severe asthma) |
Describe afterload: | load, resistance or "impedence" against which the ventri cl works |
what increases afterload? | valve stenosis, hypertension, high setemic vascular resistance, low intrthoracic pressure and ventricular dilation |
what is defined as the hearts's ability to perform work independently of pre- or afterload. Failure is ither dut to systolic dysfuntion or poor diastolic filling. | Myocardial contractility |
what circuit factor is as important as myocardial contractility in maintaining CO? | Peripheral vascular regulation that conducts venous capacitance accounts for ~ 70% of total blood volume, that can increase venous return by 30% from neurohormonal factors, systemic adrenergic, reninaldosterone, vasopressinergic, and steroid systems |
Name several features of reduced CO upon inspection: | Confusion, reduced UOP, delayed cap refill, peripheral cyanosis, pale cool limbs, |
what may be heard upon auscultation? | leaking heart valves, compensatory mechanisms (tachycard, increased SVR), hypovolemia= narrowing pulse pressure, sepsis = low diastolic bp |
what are the main diagnosis for emergency treatment? | hemorrhage, cordiac tampnade, massive pulmonary embolism |
what is the difference in treatment for Left sided heart failure and hypovolemia? | fluid restriction is meant to reduce the overall blood volume to prevent more fluid back up to the lungs in left sided heart failure vs fluid resuscitation for hemorrhage |
how do rate and rhythm affect CO? | keep K+ > 4.5 mmol/L, and Mg2+ > 1.2 mmol/L and withdraw arrhythmogenic drugs. (restore sinus rhythm and normal HR) treatment consider antiarrhythmic drugs and pacemaker |
what is assessed for in a fluid challenge? | in the absence of cardiac failulre a fluid challenge is given and assesses HR, BP, and chest Auscultation. A transient response indicates fluid resusitation, a sustained increase in CVP would risk pulmonary edema and should not receive fluid |
what is the next step in treatment of reduced CO if fluid resuscitaiton fails to achieve adequate circulation or precipitates cardiac failure? | inotropic or vasopressor drugs and mechanical ventricular support devices must be considered.```````````````````````````````````````````````````````````` |
describe the difference between oncotic and osmotic pressures: | osmotic deals with cellular ion pumps (extracellular for sodium and chloride, & Intracellular for Potassium and phosphate) while oncotic pressure deals with an albumin cycle in the ability of vascular plasma proteins to bind to water in circulation |
what factors cause critically ill patients to inability to maintain normal fluid volume? | dehydration and hyperglycemia cause ADH release = reduced UOP and causing water/sodium retent; renin angiotensis system; catecholamine release, inflammation increases vascular permeability= edema, impaired gas exchange |
Assessing fluid balance leads to choice of fluid between what types? | crystalloid, colloid, blood, bicarb, maintenance fluid, post major surgery, major hemorrhage, sepsis/septic shock, and head injury |
How do crystalloid solutions disperse in the intravascular system? | rapidly to other fluid compartments (ECF, ICF); large volumes may cause interstitial edema. hypertonics draw ICF water to ECF. Small fluid resuscitation vol and hypertonic osmotic effects may reduce cerebral edema for head trauma. |
How are colloid solutins dispersed? | large molecules dont easily diffuse out blood vessels/remain longer,pulling water/expands intravascular volume 4-5x crystalloid. Benefits hypoalbuminaemic pts, severe sepsis, ARDS. may induce clotting prob, allergic rxs, renal impairment |
why is blood given? | to maintain hemoglobin concentration of > 80 g/L or 8g/dl. |
Why is bicard given? | used to correct ph < 7.2, or metabolic acidosis due to renal or GI loss. |
what is the normal maintenance required for a euvolemic pt who cannot drink? | 2-3L water, 70-150mmol/L Na+, 40 mmol/L K+, = 1L of 0.9% Saline, 2L 5% dextrose with 20 mmol K+ added for each L 5% D. |
what is Hartman's solution? | for Hypernatremic pts use 5% dextrose, for hyponatremic pts use 0.9% Saline |
what is to be given for hypovolemia in Post surgical pts? | double the infusion rate from 1-1.5 ml/kg/hr to 2-3ml/kg/hr, maintain hemoglobin > 8 g/dl, or in cardiac pts >10 g/dl |
How does aggressive fluid resuscitation in major hemorrhage increase blood loss? | Dilutional coagulopathyacidosis and hypothermia. Blood is the ideal replacement fluid, but usually begins with 20-30 ml/kg Hartman's solution, 1-1.5 L Gelofusin(1-1.5L Vovulen) infusion rate determined by repeated assessment, inlcudes plasma/platelets |
what is monitored for sepsis and septic shock? | UOP, Lactate, fluid challenges |
what is treatment for elevated lactate and hypotension after initial 20-40 ml/kg Hartmans aliquots of .5 to 1 L? | CVP line, metrics of 8-12 mmHg, MAP >65 mmHG, UOP >0.5 ml/kg/hr and Svo2 > 70% |
what type of natremia aggravates brain edema? | a degree of nypernatremia is benficial and saline 0.9% is fecommended for fluid resuscitation. avoid 5% dextrose except in diabetes insipidus. |