500 likes | 879 Vues
Daniel R. Margulies, MD, FACS Director, Trauma and Surgical Critical Care Department of Surgery, CSMC. S. C. Los Angeles, California. Introduction to Critical Care. What’s so Special about the ICU?. Ventilators Hemodynamic Monitoring Vasoactive Drugs “Applied Physiology”.
E N D
Daniel R. Margulies, MD, FACS Director, Trauma and Surgical Critical Care Department of Surgery, CSMC S C Los Angeles, California Introduction to Critical Care
What’s so Special about the ICU? • Ventilators • Hemodynamic Monitoring • Vasoactive Drugs “Applied Physiology”
Basic Ventilator Management • Indications for Ventilation • Inability to Ventilate (high pCO2) • COPD • Inability to Oxygenate (low pO2) • ARDS • Mixed • common
Intubation • Orotracheal • Nasotracheal • Cricothyrotomy • Tracheostomy
Ventilator Orders • Initial Ventilator Orders : Volume cycled • FiO2 • Rate • Mode (AC, SIMV, PC, PS, CPAP) • PEEP • TV • Consider NG tube, art line, restraints • Check the CXR!!
Ventilator Changes • pO2: keep FiO2 <60% • PEEP • FiO2 • pCO2 • TV • Rate
Ventilator Changes • pO2 = 380 • FiO2=100% • What now?
Ventilator Changes • Remember the “Rule of 7s” • Each % change of FiO2 of 1 results in a change of pO2 of 7 pO2 - 100 • FiO2 = ------------------- 7
Weaning • PaO2 >60 on FiO2 < 0.5 with PEEP <5 • Minute vent <10 L/min • NIF more negative than -20 • VC >800 mL • TV >300 mL • Use T-piece or CPAP with PS
After Extubation • Oxygen Mask • Check ABG • Cough / Deep Breathing • Incentive Spirometer
ARDS 1. Impaired Oxygenation: PaO2/FiO2 ratio < 200 (normal > 450) 2. Bilateral pulmonary infiltrates on CXR 3. PCW < 18 (no CHF) ARDS is an acute clinical illness characterized by severe hypoxemia and bilateral infiltrates on chest X-ray in the absence of pulmonary edema.
Causes • Infection èsepsis • Trauma èhemorrhagic shock • Multiple transfusions • Low flow state from any cause • Aspiration pneumonia • Acute pancreatitis • Smoke inhalation • and many more…..
Levy G, Shabot MM, Hart M, et al: Transfusion associated non-cardiogenic pulmonary edema. Transfusion 1986;26: 278. Levy G, Shabot MM, Hart M, et al: Transfusion associated non-cardiogenic pulmonary edema. Transfusion 1986;26: 278.
Pathophysiology • Large alveolar surface area = 70 m2 (skin = 1.7 m2) • Lung sensitive to noxious stimuli - inhaled and circulating • Lung receives entire cardiac output every minute • Affected by multiple inflammatory mediators and cells
Cells Inflammatory Mediators • Thromboxane A2 • Prostacyclin • Leukotrienes • Platelet-activating factor (PAF) • Bradykinin • C3a, C5a • Tumor necrosis factor • IL-1, IL-6 • Elastase, Collagenase • Oxygen free radicals • Leucocytes • Macrophages • Monocytes • Endothelial cells • Mast cells • Bosophils • Fibroblasts • Platelets Nothing New…... Still can’t do anything about ‘em!
New Ventilator Strategies - I Goal: Reduce Alveolar distention Marcy & Marini. Chest 1991;100:494
New Ventilator Strategies • Permissive hypercapnia • Pressure controlled ventilation • Pressure release ventilation • Low volume pressure-limited ventilation • Inverse ratio ventilation • Prone ventilation
Permissive Hypercapnia Tolerate mild to moderate respiratory acidosis (elevated PCO2) in order to reduce airway pressures. • Lower tidal volumes • Lower respiratory rates • Lower peak and mean airway pressures
Prone Positioning Stocker et al. Chest 1997;111:1008
Extracorporeal CO2 Removal (ECCO2R) Status: Ineffective Guinard et al. Clin Invest Crit Care 1997;111:1000
ý ý ý ý ? Other New Ventilator Strategies • High frequency ventilation (>60/min) • High Positive End-Expiratory Pressure (PEEP) ventilation • Extra-corporeal membrane oxygenation (ECMO) • Extra-Corporeal CO2 Removal (ECCOR) • Partial Liquid Ventilation
Partial Liquid Ventilation Leach et al. Crit Care Med 1993;21:1270.
PaO2 PaCO2 pH Partial Liquid Ventilation Status: Unproven Conventional Vent Partial Liquid Vent
New Pharmacologic Strategies • Inhaled nitric oxide (NO) • Surfactant replacement • Ketoconazole • Prostaglandin E1 • Non-steroidal anti-inflammatory agents • High dose steroids (again)
Pharmacologic Treatment of ARDS Kollef & Schuster. NEJM 1995;332:27.
How the SICU Does It Patient R.N. • 31 y/o female • 2 days S/P laparoscopic GYN procedure • Found hypotensive, febrile on ward • CT abdomen - fluid collections & air • OR ð SB perf + massive contamination • SICU postop - hypotensive on vent
Surgical ICU Management • Hemodynamic/Swan-Ganz monitoring • Volume resuscitation > 20L (sepsis) • Triple antibiotics • Dopamine, neosynepherine • CT guided abscess drainage • Repeat laparotomy & drainage
Ventilator Management • A/C volume vent ð Pressure Control vent • Inverse Ratio ventilation • Paralysis & sedation > 10 days • Permissive hypercapnia • High PEEP (as required) 15 cm H2O • High FiO2 (as required) 100% ~ 7 days • Tracheostomy
ü ? ARDS Management Principles ü ü Brandstetter RD. Heart Lung 1997;26: 3-14
ARDS Prognosis - Overall Milberg at al. JAMA 1995;273:306.
The News on ARDS in Summary The good news is……. The prognosis and survival for ARDS is improving! The bad news is……. WE’RE NOT EXACTLY SURE WHY!
SHOCK A state in which tissue perfusion and/or nutrient uptake fails to meet the body's metabolic needs. Shock can occur with low, high or normal cardiac output. • Cardiogenic • Hypovolemic • Septic • Neurogenic • Cardiac compressive
CONTROL OF CARDIAC OUTPUT • PRELOAD • left ventricular end diastolic pressure • AFTERLOAD • pressure against which the left ventricle • must eject blood • HEART RATE • CONTRACTILITY • strength of left ventricular contraction
CONTROL OF CARDIAC OUTPUT • Normal Hemodynamic Parameters : • MAP - 70-110 mmHg • SVR - 900-1200 dynes/cm square • PVR - 80-120 dynes/cm square • CO - 4-7 L/min
CONTROL OF CARDIAC OUTPUT • Normal Hemodynamic Parameters : • DO2 - 700-1400 ml/O2/square meter • VO2 - 180-280 ml/O2/square meter • O2 extraction - 20-30% • Qs/Qt - 3-5% • Ca O2 - 16-22 vol% • Cv O2 - 12-16 vol%
Hemodynamic Parameters • SVR = ( MAP - RAp/ CO ) x 80 - systemic vascular resistance • PVR = ( PAP - PAOP/ CO ) x 80 - pulmonary vascular resistance • CO = VO2 / ( CaO2 - CvO2 ) - cardiac output • DO2 = CO x Ca O2 x 10 - Oxygen delivery • MAP = mean arterial pressure, PAP = pulmonary artery pressure, RAp = central venous pressure ( RA pressure ), PAOP = pulmonary artery occlusion pressure )
Hemodynamic Parameters • VO2 = ( Ca O2 - Cv O2 ) x CO x10 - Oxygen consumption • Ca O2 = ( 1.39 x Hb x SaO2 ) + ( 0.003 x PaO2 ) - Arterial O2 content • Cv O2 = ( 1.39 x Hb x SvO2 ) + ( 0.003 x PvO2 ) - Venous O2 content • O2 extraction = VO2 / DO2 • Qs/Qt = ( PA-a O2 ) / ( PA-a O2 ) / ( Ca-v O2 ) - Shunt fraction • Pa O2 = partial arterial oxygen pressure.
Intensive Care Medicine • Ventilators • ARDS • Hemodynamic Monitoring • Vasoactive Drugs