Surgical Critical Care and Emergency Surgery. Группа авторов

heart failure?Adaptive myocyte remodeling.Volume overload of the ventricle.Cell loss secondary to increased oxygen demand.Impaired ventricular wall relaxation.Change of ventricle from elliptical to globular.Diastolic heart failure stems from incomplete relaxation of the ventricle. Three pathophysiologic pathways include impaired ventricular wall relaxation, as left atrial pressure exceeds left ventricular pressure causing pulmonary edema; increased stiffness of the ventricle secondary to increased wall thickness and decreased internal diameter often seen with poorly controlled hypertension; excess collagen deposition as myofibrils are laid in parallel secondary to ischemia, as seen with MI, impairing contractility. The pathophysiology of systolic failure involves adaptive myocyte remodeling, as occurs with CAD, changing ventricular shape resulting in an increasingly overloaded ventricle with decreasing contractility resulting in cell loss due to increased oxygen demand and eventual change of the ventricle from elliptical to globular.Answer: DZile MR, Baicu CF and Gaasch WH . Diastolic heart failure – abnormalities in active relaxation and passive stiffness of the left ventricle. NEJM. 2004; 350: 1953–1959.

      13 You are utilizing central venous pressure monitoring to guide resuscitation of a patient with a 60% TBSA burn injury in your ICU. Which of the following components of the CVP waveform represents isovolumic contraction?c wavex descenta wavey descentv waveCVP Waveform componentMechanical eventa waveAtrial contractionc waveIsovolumic contractionv waveSystolic filling of the atriumx descentAtrial relaxation, systolic collapsey descentEarly diastolic filling, diastolic collapseAnswer: AMagder S . Central venous pressure: a useful but not so simple measurement. Crit Care Med. 2006; 34: 2224–2227.

      14 Which component of the cardiac cycle is represented by the answer given above?Early diastoleEarly systoleEnd diastoleMid‐systoleEnd systoleThe a wave occurs from right atrial contraction increasing venous pressure. Right ventricular contraction displaces the tricuspid valve into the right atrium, represented by the c wave. With the emptying of right ventricle, the right atrium relaxes and begins to fill, represented by the x descent. The v wave demonstrates the filled right atrium with increased atrial pressure. Finally, the y descent shows right ventricular filling as the tricuspid valve opens.CVP Waveform componentCardiac cycle eventa waveEnd diastolec waveEarly systolev waveLate systolex descentMid‐systoley descentEarly diastoleAnswer: BMagder S . Central venous pressure: a useful but not so simple measurement. Crit Care Med. 2006; 34: 2224–2227.

      15 Which of the following is NOT a physiologic effect of minimally invasive left ventricular assist device?Decreased left ventricular end diastolic pressure.Decreased left ventricular wall tension.Increased diastolic pressure.Increased mean arterial pressure.Increased pulmonary capillary pressure.A minimally invasive left ventricular assist device is a miniature axial pump that allows blood to be aspirated from the left ventricle into the cannula component of the pump and expelled above the aortic valve into the ascending aorta. The device has been used for support in high‐risk percutaneous coronary intervention as well as cardiogenic shock. The device works to unload the left ventricle reducing left ventricular end diastolic pressure and wall tension. This allows for decreased oxygen demand. Furthermore, it increased mean arterial pressure, diastolic pressure, and cardiac output, thereby improving both systemic and coronary blood flow. Finally, it decreases pulmonary capillary pressure and thereby right ventricular afterload.Answer: EBurzotta F, Trani C, Doshi S, et al. Impella ventricular support in clinical practice: collaborative viewpoint from a European expert user group. Int J Cardiol. 2015; 201: 684–691.

      16 Which of the following is a physiologic impact of intra‐aortic balloon pumps during systole?Increased systolic blood pressure.Decreased pre‐systolic aortic pressure.Increase in the isometric phase of left ventricular contraction.Increased left ventricular wall tension.Decreased left ventricular ejection fraction.The intra‐aortic balloon pump follows the principle of counterpulsation i.e. inflation during diastole with deflation during systole. The physiologic impacts during the systolic phase include a decrease in aortic systolic pressure as well pre‐systolic (end‐diastolic) aortic pressure both of which contribute to decreased afterload by 10% and 30%, respectively; decrease in the isometric phase of left ventricular contraction, thereby reducing myocardial oxygen consumption; decreased left ventricular wall tension by 20%; increased left ventricular ejection fraction by up to 30%.Answer: BParissis H, Graham V, Lampridis S, et al. IABP: history‐evolution‐pathophysiology‐indications: what we need to know. J Cardiothorac Surg. 2016; 11(1): 122.

      17 Which of the following is an expected cardiovascular change during pregnancy?Decreased heart rate.Decreased cardiac output.Increased peripheral vascular resistance.Decreased ventricular distension.Decreased systemic vascular resistance.Pregnancy results in increased heart rate, increased cardiac output, decreased peripheral vascular resistance, increased ventricular distension, and decreased systemic vascular resistance.Answer: EHill CC and Pickinpaugh J . Physiologic changes in pregnancy. Surg Clin N Am. 2008; 88: 391–401.

      18 Which of the following is a mechanism by which vasodilators improve cardiac function in acute decompensated heart failure?Increased ventricular preload.Decreased stroke volume.Increased ventricular afterload.Increased cardiac output.Increased ventricular filling pressure.The pathophysiology of acute heart failure involves increased myocardial oxygen demand with increased ventricular filling pressures, low cardiac output, and increased systemic vascular resistance. Nitroprusside and nitroglycerin remain two of the most potent vasodilators used in therapy. Nitrogylcerin is a venodilator working to decrease preload, decrease afterload, and myocardial oxygen demand. Nitroprusside is an arterial and venous dilator decreasing preload, afterload, myocardial oxygen demand as well as increasing stroke volume and cardiac output.Answer: DCarlson MD and Eckman PM . Review of vasodilators in acute decompensated heart failure: the old and new. J Card Fail 2013; 19(7): 478–493.

      19 Which of the following is an expected effect of increased intrapleural pressure from positive pressure ventilation?Increased venous return.Increased aortic pressure.Baroreceptor dampening.Increased systemic vascular resistance.Increased preload.With positive pressure ventilation, increased intrapleural pressure results in initially increased aortic pressure causing compensatory reduction in systemic vascular resistance and left ventricular afterload by activated baroreceptors, thereby increasing cardiac output. Positive pressure additionally decreases venous return and, therefore, preload.Answer: BAlviar CL, Miller PE, McAreavey D, et al. Positive pressure ventilation in the cardiac intensive care unit. J Am Coll Cardiol. 2018; 72: 1532–1553.

      20 A 70‐year‐old woman in a motor vehicle collision undergoes a splenectomy for Grade IV laceration and receives four units of whole blood in the OR but arrives in the ICU tachycardiac and hypotensive. Point of care hemoglobin is 14.3 mg/dL 2 hours post‐transfusion. Her abdomen was left open and minimal output is coming from her negative pressure abdominal dressing. She has multiple rib fractures and a radius fracture. Which of the following therapies would promote end‐organ perfusion?Decrease vasoactive drug doses (decrease peripheral vascular resistance).Increase sedation and pain medications to decrease her heart rate.Increase end‐diastolic volume with volume resuscitation.Increase contractility with positive inotrope.Increase end‐systolic volume.This patient has evidence of blunt chest trauma with multiple rib fractures and tachycardia. While she could have hypovolemic shock from her splenic injury and intraoperative blood loss, she remains hypotensive despite transfusions with a hemoglobin of 14.3 mg/dL making this less likely and no evidence of ongoing bleeding from her abdomen. This makes it less likely that further volume resuscitation with blood or crystalloid would be helpful. Blunt cardiac injury can occur with blunt chest trauma and is initially screened for with EKG and troponin assessment, followed by an echocardiogram. Blunt cardiac injury may be improved with positive inotropic medications.Decreasing vasoactive drug doses would worsen hypotension and worsen end‐organ perfusion. Vasopressors are often used in supportive treatment for blunt cardiac injury and may need to be increased to promote end‐organ perfusion. Increasing sedation and pain medications may improve her tachycardia but would worsen her hypotension and end‐organ perfusion. Increasing end‐systolic volume would decrease her stroke volume and cardiac output further, worsening her end‐organ perfusion.Remember: Answer: DLevick JR. An Introduction to Cardiovascular Physiology. Butterworth and Co., London, 2013.Clancy K, Velopulos C, Bilaniuk JW, et al. Screening for blunt cardiac injury: An Eastern Association for the Surgery of Trauma practice management guideline. J Trauma Acute Care Surg. 2012; 73 5: S301–S306.

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