Introduction to Critical Care
Daniel R. Margulies, MD, FACS
Director, Trauma and Surgical Critical Care
Department of Surgery, CSMC
C S
Los Angeles, California
Introduction to Critical Care
What’s so Special about the ICU?
Ventilators
 Hemodynamic Monitoring
 Vasoactive Drugs

“Applied Physiology”
Introduction to Critical Care
Basic Ventilator Management

Indications for Ventilation
 Inability
to Ventilate (high pCO2)
 COPD
 Inability
to Oxygenate (low pO2)
 ARDS
 Mixed
 common
Introduction to Critical Care
Intubation
Orotracheal
 Nasotracheal
 Cricothyrotomy
 Tracheostomy

Introduction to Critical Care
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!!

Introduction to Critical Care
Ventilator Changes

pO2: keep FiO2 <60%
 PEEP
 FiO2

pCO2
 TV
 Rate
Ventilator Changes
Introduction to Critical Care
pO2 = 380
 FiO2=100%
 What now?

Ventilator Changes
Introduction to Critical Care
Remember the “Rule of 7s”
 Each % change of FiO2 of 1 results in a
change of pO2 of 7

pO2 - 100
  FiO2 = ------------------7
Introduction to Critical Care
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

Introduction to Critical Care
After Extubation
Oxygen Mask
 Check ABG
 Cough / Deep Breathing
 Incentive Spirometer

Introduction to Critical Care
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.
Introduction to Critical Care
Causes
• Infection  sepsis
• Trauma  hemorrhagic shock
• Multiple transfusions
• Low flow state from any cause
• Aspiration pneumonia
• Acute pancreatitis
• Smoke inhalation
• and many more…..
Introduction to Critical Care
Levy G, Shabot MM, Hart M, et al: Transfusion associated noncardiogenic pulmonary edema. Transfusion 1986;26: 278.
Introduction to Critical Care
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
Introduction to Critical Care
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!
Introduction to Critical Care
Causes & Time of Death After Multiple Trauma
Introduction to Critical Care
New Ventilator Strategies - I
Goal: Reduce Alveolar distention
Marcy & Marini. Chest 1991;100:494
Introduction to Critical Care
New Ventilator Strategies
• Permissive hypercapnia
• Pressure controlled ventilation
• Pressure release ventilation
• Low volume pressure-limited ventilation
• Inverse ratio ventilation
• Prone ventilation
Introduction to Critical Care
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
Introduction to Critical Care
Prone Positioning
Stocker et al. Chest 1997;111:1008
Introduction to Critical Care
Extracorporeal CO2 Removal (ECCO2R)
Status: Ineffective
Guinard et al. Clin Invest Crit Care 1997;111:1000
Introduction to Critical Care
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
?
Introduction to Critical Care
Partial Liquid Ventilation
Leach et al. Crit Care Med 1993;21:1270.
Introduction to Critical Care
Partial Liquid Ventilation
PaO2
PaCO2
Status: Unproven
pH
Conventional Vent
Partial Liquid Vent
Introduction to Critical Care
New Pharmacologic Strategies
• Inhaled nitric oxide (NO)
• Surfactant replacement
• Ketoconazole
• Prostaglandin E1
• Non-steroidal anti-inflammatory agents
• High dose steroids (again)
Introduction to Critical Care
Pharmacologic Treatment of ARDS
Kollef & Schuster. NEJM 1995;332:27.
Introduction to Critical Care
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  SB perf + massive contamination
• SICU postop - hypotensive on vent
Introduction to Critical Care
4/5
Introduction to Critical Care
4/11
Introduction to Critical Care
Surgical ICU Management
• Hemodynamic/Swan-Ganz monitoring
• Volume resuscitation > 20L (sepsis)
• Triple antibiotics
• Dopamine, neosynepherine
• CT guided abscess drainage
• Repeat laparotomy & drainage
Introduction to Critical Care
4/13/
Introduction to Critical Care
Ventilator Management
• A/C volume vent  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
Introduction to Critical Care
4/20
Introduction to Critical Care
ARDS Management Principles



?
Brandstetter RD. Heart Lung 1997;26: 3-14
Introduction to Critical Care
ARDS Prognosis - Overall
Milberg at al. JAMA 1995;273:306.
Introduction to Critical Care
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!
Introduction to Critical Care
Hemodynamic Monitoring and
Vasoactive Drugs
SHOCK
Introduction to Critical Care
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
Introduction to Critical Care


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
Introduction to Critical Care
Pulmonary Artery Catheter
Introduction to Critical Care
Starling Curves
Introduction to Critical Care
Catheter Insertion Waveforms
Introduction to Critical Care
CONTROL OF CARDIAC OUTPUT
Introduction to Critical Care
CONTROL OF CARDIAC OUTPUT
Introduction to Critical Care
• 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
Introduction to Critical Care
• 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
Introduction to Critical Care
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
Introduction to Critical Care
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.
Introduction to Critical Care
Intensive Care Medicine

Ventilators
 ARDS
Hemodynamic Monitoring
 Vasoactive Drugs
