1 / 14

CARDIAC SEQUELAE OF IAH / ACS Michael L. Cheatham, MD, FACS, FCCM

Pulmonary  PIP, Paw  Qsp/Qt, Vd/Vt  compliance atelectasis hypoxia hypercarbia. CNS  ICP  CPP. Cardiovascular hypovolemia  venous return  CO  SVR  PAOP, CVP. Thoracoabdominal elevated diaphragm  intrathoracic pressure IVC distortion  wall compliance

Download Presentation

CARDIAC SEQUELAE OF IAH / ACS Michael L. Cheatham, MD, FACS, FCCM

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Pulmonary •  PIP, Paw •  Qsp/Qt, Vd/Vt •  compliance • atelectasis • hypoxia • hypercarbia • CNS •  ICP •  CPP • Cardiovascular • hypovolemia •  venous return •  CO •  SVR •  PAOP, CVP • Thoracoabdominal • elevated diaphragm •  intrathoracic pressure • IVC distortion •  wall compliance •  abd wall blood flow • Hepatic •  portal blood flow •  lactate clearance • Renal •  renal blood flow •  UOP •  GFR • Gastrointestinal •  celiac / SMA blood flow •  mucosal blood flow CARDIAC SEQUELAE OF IAH / ACS Michael L. Cheatham, MD, FACS, FCCM Director, Surgical Intensive Care Units Orlando Regional Medical Center Orlando, Florida, USA

  2. SETTING THE STAGE FOR IAH / ACS • Preload, contractility, afterload, and oxygen transport are commonly abnormal in the critically ill • Subsequent development of sepsis, shock, or acute lung injury can further worsen cardiac function • Inadequate resuscitation and failure to restore cellular oxygen delivery leads to • Ischemia • Anaerobic metabolism • Multiple organ dysfunction syndrome (MODS) • Death

  3. THE IMPACT OF ITP AND IAP • Elevated intra-thoracic (ITP) and intra-abdominal pressure (IAP) causes • Cephalad deviation of the diaphragm • Cardiac compression • Pulmonary compression • Can have marked effects on preload, contractility, afterload, and oxygen transport

  4. OBJECTIVES • To discuss the pathophysiologic impact of ITP and IAP on • Preload • Contractility • Afterload • Oxygen Transport • To consider the therapeutic interventions necessary to correct cardiac dysfunction

  5. PRELOAD • Adequate intravascular volume is essential • Loss of intravascular volume may be either • Absolute • Hemorrhage • Third-space fluid losses • Relative • Mechanical obstruction to blood flow • Anatomic • Pressure-induced • Thrombosis

  6. PRELOAD • Cephalad elevation of the diaphragm • Induces narrowing of the inferior vena cava (IVC) • Reduces blood return to the heart • Elevated IAP • Compresses the IVC • Limits blood return from below the diaphragm • Causes lower extremity and pelvic blood pooling • Promotes both genital and lower extremity edema • Places patient at risk for deep venous thrombosis • Such changes may occur with an IAP of 10 mmHg

  7. PRELOAD • Inadequate venous return decreases cardiac output (CO) through decreased stroke volume (SV) • CO reduction is proportional to volume status • Hypovolemic patients sustain CO reductions at lower levels of IAP than do normovolemic patients • Hypervolemic patients demonstrate increased venous return in the presence of elevated IAP • Volume resuscitation can overcome both the anatomic and pressure-related restrictions to venous return restoring SV and CO

  8. CONTRACTILITY • Diaphragmatic elevation and direct cardiac / pulmonary compression • Reduces biventricular preload • Elevates pulmonary artery pressures • Elevates pulmonary vascular resistance • In response, the thin-walled right ventricle dilates • Interventricular septum may bulge into the left ventricular chamber, impeding left ventricular function and decreasing cardiac output • May result in systemic hypotension, worsening right coronary artery blood flow

  9. CONTRACTILITY • At a time when right ventricular function is essential to maintaining CO • Right ventricular ejection fraction decreases • Right ventricular wall tension increases • Myocardial oxygen demand increases • Subendocardial ischemia may occur • Right ventricular dysfunction can become severe resulting in left ventricular failure due to "ventricular interdependence"

  10. CONTRACTILITY • Volume resuscitation and inotropic support will improve biventricular contractility at mild to moderate levels of IAH • Restores preload • Improves ventricular function • Increases coronary perfusion pressure • The cardiac dysfunction of severe IAH and ACS can only be reversed by decompressive laparotomy • Delayed intervention may prove to be futile

  11. AFTERLOAD • Generally increases to compensate for reduced venous return and falling SV • Elevated ITP and IAP pathologically • Increases systemic vascular resistance through direct compressive effects on the aorta and systemic vasculature • Increases pulmonary vascular resistance through compression of the pulmonary parenchyma

  12. AFTERLOAD • Poorly tolerated by patients with • Inadequate intravascular volume • Marginal cardiac contractility / prior dysfunction • Acute lung injury requiring PEEP • Preload augmentation appears to initially ameliorate the increased afterload • Decompressive laparotomy is most effective for reducing vascular resistance to appropriate levels

  13. OXYGEN TRANSPORT • Cellular delivery of oxygen is essential to avoiding multiple organ dysfunction • Efficient oxygen delivery requires appropriate • Preload • Contractility • Afterload • Alveolar oxygenation • Interventions aimed at reducing ITP and IAP are essential to improving oxygen delivery and transport balance

  14. CONCLUSIONS • Cardiovascular dysfunction plays a major role in the organ dysfunction and failure that characterizes IAH/ACS • Optimal cardiac function is essential to avoiding multiple organ dysfunction and improving outcome • Preload, contractility, afterload, and oxygen transport balance are all interrelated • Correction of one component frequently mandates treatment of all

More Related