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10/9/2017
1
Leanna R. Miller, DNP, RN, CCRN-CMC, PCCN-CSC, CEN, CNRN, CMSRN, NP
Education Specialist
LRM Consulting
Nashville, TN
NO DISCLOSURES
Objectives
Identify the 5 criteria for the diagnosis of ARDS.
Discuss the common etiologies that lead to ARDS.
Describe the priorities in the management of patients with ARDS.
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diffuse lung injury resulting in
noncardiogenic pulmonary
edema due to increase in
capillary permeability
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• refractory hypoxemia
• diminished compliance
• diffuse infiltrates on chest x-ray
• normal PAOP
• PaO2 / FiO2 ratio < 200
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• Etiology
–shock
– trauma
– infections
– inhaled toxins
• Etiology
– aspiration
– near-drowning
– massive blood transfusions
– fat or amniotic fluid emboli
– pancreatitis
• Phase I & II
–subclinical respiratory distress
–ABGs (respiratory alkalosis)
–hyperventilating
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• Phase III
– established respiratory distress
– pulmonary shunt > 10% above baseline
– chest x-ray shows infiltrates
– crackles in lung bases
• Phase IV
–severe respiratory failure
– rising pCO2
– rising physiologic shunt
–white-out on chest x-ray
• Diagnosis
–history
–signs/symptoms
– labs (ABGs)
–x-ray
–hemodynamics
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• Treatment
–establish patent
airway
– restore arterial O2
level
• Mechanical Ventilation
– conventional with PEEP
–PC / IRV
–HFJV
–APRV
• Goals of mechanical ventilation in
ARDS are to:
–maintain oxygenation
– avoiding oxygen toxicity and the
complications of mechanical
ventilation
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• maintain oxygen saturation in the range of
85-90%
• aim of reducing the fraction of inspired
oxygen (FIO2) to less than 60% within the
first 24-48 hours
• usually requires the use of moderate-to-high
levels of PEEP
• experimental studies have shown that
mechanical ventilation may promote a type
of acute lung injury (ALI) termed ventilator-
associated lung injury
• protective ventilation strategies using low
tidal volumes and limited plateau pressures
improves survival when compared with
conventional tidal volumes and pressures
• ARDS Network study
– patients with ALI and ARDS were randomized to
mechanical ventilation
• tidal volume of 12 mL/kg of predicted body
weight and an inspiratory pressure of 50 cm
water or less
• tidal volume of 6 mL/kg and an inspiratory
pressure of 30 cm water or less
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• the study was stopped early after interim
analysis of 861 patients demonstrated that
subjects in the low-tidal-volume group had
a significantly lower mortality rate (31%
versus 39.8%)
• mechanical ventilation with a tidal
volume of 6 mL/kg predicted body
weight is recommended, with
adjustment of the tidal volume to
as low as 4 mL/kg if needed to limit
the inspiratory plateau pressure to
30 cm water or less
• increase the ventilator rate and
administer bicarbonate as needed
to maintain the pH at a near normal
level (7.3)
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• High-frequency ventilation uses low
tidal volumes and high respiratory
rates.
• diminishes alveolar distention
• compared to conventional ventilation in
adults demonstrates early improvement
in oxygenation but no improvement in
survival.
• Fluid Management
–maintain adequate perfusion
– isotonic solutions
– fluid restriction
–consider diuretics**Seeley (2013) Updates in the management
of acute lung injury: A focus on the overlap
between AKI and ARDS. Advances in
Chronic Kidney Disease, 20(1): 14-20.
• primary ARDS due to aspiration, pneumonia,
or inhalational injury treated with fluid
restriction
• secondary ARDS due to remote infection or
inflammation requires initial fluid and
potential vasoactive drug therapy
• essential in directing initial treatments to
stabilize the patient
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• Improve systemic O2Delivery
– modest volume expansion
– vasopressors/vasodilators
• Sedation
– control anxiety & physical activity
– may require addition of neuromuscular blocker
– suggestions:
• propofol
• versed
• Positioning
– “good lung” in dependent position
– both lungs are equally injured
– beneficial positions include:
• prone
• right lung down
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• 60-75% of patients with ARDS have
significantly improved oxygenation
when turned from the supine to the
prone position
• improvement in oxygenation is rapid
and often substantial enough to allow
reductions in FiO2 or level of CPAP
• Possible mechanisms for improvement
are:
– recruitment of dependent lung zones
– increased functional residual capacity (FRC)
– improved diaphragmatic excursion
– increased cardiac output
– improved ventilation-perfusion matching
• despite improved oxygenation with
the prone position, randomized
controlled trials of the prone
position in ARDS have not
demonstrated improved survival
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• Pharmacologic Therapy
– corticosteroids
– antimicrobials
– non - steroidal anti -inflammatory agents
– anti – pyretic
– “Star – Trek Meds”
• No drug has proved beneficial in the
prevention or management of acute
respiratory distress syndrome (ARDS).
• Hemoglobin
– 12 to 15 gm / dL
– factors decreasing offloading:
• hypophosphatemia
• alkalosis
• hypothermia
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• Nutritional Support
– often overlooked in ARDS
– ingredients required:
• stress amino acid
• trace elements
• omega 3 / omega 6
– Oxepa or Impact
• patients who required mechanical
ventilation within 48 hours of
developing acute lung injury
received either trophic or full
enteral feeding for the first 6 days
• Initial lower-volume trophic enteral
feeding did not improve
– ventilator-free days
– 60-day mortality
– infectious complications
– it was associated with less
gastrointestinal intolerance
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• Other Therapeutics
– nitric oxide
– surfactant
–ECMOa
– partial liquid ventilation
a Michaels, et al (2013) Adult refractory hypoxemic ARDS treated with ECMO,
American Journal of Surgery. 205(5): 492-498.
Extracorporeal Membrane Oxygenation
(ECMO)• Description
– type of cardiopulmonary
bypass
– CO2 removal; O2 replacement
– ventilated (lower VT, FiO2, &
PEEP)
Extracorporeal Membrane Oxygenation
(ECMO)
• Complications
– technical difficulties
– cannula malposition
– hemorrhage
– sepsis
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• ECMO appeared to improve survival in
patients with H1N1-associated ARDS
who could not be oxygenated with
conventional mechanical ventilation
• randomized controlled trial that
compared partial liquid with
conventional mechanical ventilation
– partial liquid ventilation resulted in
increased morbidity
• pneumothoraces
• hypotension
• hypoxemic episodes
– trend toward higher mortality
Case Study
48 - year old alcoholic with GI bleed & pancreatitis
severe epigastric pain, acute abdomen
ultrasound confirms enlarged, edematous pancreas
hemodynamically unstable
refractory hypoxemia
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Case Study
HR 130
BP 80 / 50 / 62
Case Study
HR 130
BP 80 / 50 / 62
CI 2.2
PAP 15 / 8 / 10
PAOP / CVP 2 / 1
Case Study
PVRI 290
SVRI 2218
SVI 28
LVSWI/RVSWI 22.8 / 2.6
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Case Study
ABGs (.70 FiO2)
pH 7.38
pCO2 45
pO2 50
SaO2 .83
HCO3 27
SvO2 60%
Case Study
PaO2 / FiO2 Ratio (P/F)
• 50 / .70
• 71
Normal = > 300
ALI = < 250
ARDS = < 200
Case Study
Laboratory Values
Na 150
Cl 96
Hgb / Hct 12.1 / 36.3
CO2 26
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Case Study
Anion Gap
• Na – (CO2 + Cl)
• 150 – (96 + 26)
• 28
(Normal = 12 – 15)
PEEP can DOI2 WOB VOI2 triggers inflammatory
response
maldistributed blood flow VOI2
ideal Hgb is 12
DOI2 until
VOI2 plateaus
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Case Study
DOI2 = CI ( 1.38 x Hgb x SaO2) 10
2.2 X 1.38 X 12.1 X 0.83 x 10
305 mL/min/m2
(normal = 360 - 600 mL/min/m2)
Case Study
VOI2 = CI X 1.38 X Hgb X (SaO2 - SvO2) X 10
2.2 x 1.38 x 12.1 x (.83 - .60) x 10
84 mL/min/m2
(Normal 220 - 290 mL/min/m2)
In Summary
• 6 P’s of ARDS Management
–Pathophysiology
–Prevention
–Positive Pressure Ventilation
–Perfusion
–Pharmacology
–Positioning
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