Acute Respiratory Distress Syndrome(ARDS)
The Extreme
Sue A. Ravenscraft, MDPulmonary, Sleep, and Critical Care
Park Nicollet/Methodist HospitalClinical Professor of Medicine
University of Minnesota Medical School
The Case
ECMO
Management of ARDS• Mechanical Ventilation strategies• Prone Ventilation• Novel/Adjunctive Therapy
Case
19 year old female college student• Lives in the dormitory• Healthy, non-smoker• No recent travel, trauma, exposures• Influenza vaccine current
Emergency Department1 day of dry cough/emesis
T = 99.3, Sat 97% Lungs: left base
• Influenza negative• Azithromycin
Urgent Care (Day 2)Fever with persistent cough,
appetite Physical exam:
Temp: 39.2, RR 32, HR 144, BP 108/82, 93% on RAModerately dehydrated and febrile wbc 5.8
2 L IV SalineIM CeftriaxoneΔ oral Levofloxacin
ED/Admission (Day 3)Continued cough and emesis with
diarrhea, fever and chest pain
Temp 100.8, 169/87, HR 128, RR 18 O2 96 % (3 L/min)
Creat 2.3Given fluids, Ceftriaxone,
azithromycinAdmitted to Medicine floor
Admission CXR
RETTachypneic (rr=60) and O2 sats
40%. Patient complaining of dyspnea, chest pain with coughing and deep inspiration
2130 0000 0434 0445
BP 127/72 126/79 158/87
HR 118 108 137 138
Temp 98.6 99.1 99.7
Resp 48 40 69
O2 94% 93% 60% 79%
RET Temp 99.7, HR 137, BP 158/87, RR 68, O2
60%Alert in severe distress, speaking in 1 word phrasesLungs: coarse BS, breath sounds
• Moved to ICU • Non-invasive
ventilation (BiPAP)
7.38/36/45/20
ICU• Increased work of breathing continues on high flow oxygen • Intubated
A/P:Respiratory failure with ARDS and
bilateral pneumonia• Low tidal volume: VT 380, RR 24, PEEP 10, FiO2 90%• Nebulized Epoprostenol (Flolan™)• Bronchoscopy when stable• Consult Nephrology and ID
Berlin Definition of ARDS 2012(JAMA 2012; 307:2526)
• Symptoms within 1 week of clinical insult, or new or worsening symptoms during week
• Bilateral opacities consistent with pulmonary edema on CXR/CT Opacities not be explained by pleural effusions, lobar collapse, or pulmonary nodules
• No underlying cardiac failure or fluid overload• Measured PaO2/FiO2 on PEEP ≥ 5 cm H20
Mild: > 200 mmHg ≤ 300 mmHgModerate: > 100 mmHg ≤ 200 mmHgSevere: ≤ 100 mmHg
pH: 7.38/36.2/ 45.5/20.8 Oxymizer 15L (delivers between 65-75% FiO2)Pa02/Fi02: 65 mmHg
Incidence: ARDS inpatient 15-19 years of age: 16 per 10,000 persons-years
ARDS: Etiology
Common causes: (> 60 identified)• Sepsis *• Aspiration *• Pneumonia *• Severe trauma• Massive Transfusion• Transfusion related acute lung injury (TRALI)• Lung and hematopoietic stem cell transplant• Drug and alcohol
Risk factors: Genetic determinants, cigarette smoking, cardiopulmonary bypass, pneumonectomy, acute pancreatitis, obesity, and near drowning
ARDS: Definition Disease of the lung parenchyma that leads
to impaired gas exchange. It is associated with pulmonary cytokine release, impaired endothelial barriers, loss of surfactant, fluid accumulation in the alveoli and, later, fibrotic changes.
ICU Day 5Nephrology: likely acute kidney injury in
setting of critical illness with subsequent transition to ATN• Creat 4.5• Oliguric• 5 kg in 24 hours• Multiple labs sent
Infectious Disease: Bilateral pneumonia/pneumonitis in immunocometent host• Serologies, cultures and bronchoscopy non-
diagnostic• Vancomycin, Pipracillin-Tazobactam/Levofloxacin
7.23/40/69/16Sat 93.9
VT 380 ml, FIO2 60%, PEEP 10 PaO2/FiO2: 116 (Moderate ARDS)
• Continues nebulized high-dose Epoprostenol (Flolan)
• Patient drops saturations with movement recovers quickly
• Anuric and started CRRT today
• Prone ventilation deferred due to CRRT
ICU Day 6
7.21/69/66/27 Sats 91.8%RR 24, FIO2 80%, PEEP 12, PC +25PaO2/FiO2: 83 (severe ARDS)
• Sats marginal with permissive hypercapnia.
• Bronchoscopy done with removal of thick secretions
• Proned
ICU Day 8
pH 7.30/50/122/24RR 24, VT 430 ml, FiO2
100%, PEEP 12, PC 33
Marginal improvement after proning; continues to be very difficult to ventilate and oxygenate
CRRT tolerated while prone
ICU Day 9
It Didn’t Work!
ICU Day 10• Worsened overnight• Intolerant of supine position• Sats in 70s with any
movement• Unable to transfer• U of MN contacted
and arranged for transport on ECMO
The Transport:One Chance
The Team:U of MN
Cardiac surgeon, Fellow
2 prefusionists
Transport paramedicsMethodist
ICU nurses, OR nurses, RT, Intensivist, Critical Care Fellow, Nephrologist, Cardiologist, Echo Tech
Catheters Placed
UMN: Day 3
• ECMO continues• Lung transplant
Considered• No improvement
Lung Transplant Consult: (Day 4)
Renal failure a significant contraindicationNeurologic status is not knownDiscussed poor prognosis and the general
survival data of lung transplant with patient’s family. Agreeable with lung transplant as a last option.
Median survival for single-lung recipients is 4.6 years. Median survival for double-lung recipients is 6.6 years
Lung Transplant evaluation
Decision made by transplant surgeon and pulmonologist on service to proceed with emergent listing for bilateral lung transplant
LAS score (Lung allocation score)May 2005
Reducing the number of deaths on lung transplant waiting list
Ensuring the efficient and equitable allocation of lungs to active transplant candidates
Assigns a score ranging from 0 to 100 to all candidates older than age 12. It is a weighted combination of the predicted risk of death during the following year on the waiting list and the predicted likelihood of survival during the first year following transplantation.
Higher lung allocation scores indicate the patient is more likely to benefit from a lung transplant.
UMN: Day 10
• Bilateral sequential lung transplantation with cardiopulmonary bypass support
• Chest closure (4 days afterwards)
• Tracheostomy (11 days afterwards)
EDDay 0
UCDay 2
AdmissionDay 3
RET
ICUDay 4
Transplantevaluation
UMN
ECMO(Day 10)
Dialysis Prone position
Lung Transplantation (Day 20)
Native Lung
Pathology: Diffuse alveolar damage
Follow-up: Present day
19 year-old, healthy, female with ARDS of unknown etiology despite extensive infectious, rheumatologic, and pulmonary workup. ECMO as bridge to BSLTx
Slow recovery requiring tracheostomy and rehab
Home 3 months after transplant
Kidney function did not return.Successful living related donor kidney transplant 5 months later
Now home and off dialysis
ECMO(Extracorporeal Membrane
Oxygenation)Mechanical devices to
temporarily support the failing heart or lungs• Cardiopulmonary bypass used in
OR for short term support• VA ECMO drains from RA or IJ
through membrane lung returned to femoral or subclavian artery (cardiac)
• VV ECMO drains from IVC through membrane lung returned to IJ (lung)
VV ECMO
VV ECMO
Cannulas are large (31 Fr)• Double lumen available• Flow 4-5 L/min
Minimal lung ventilation• Plateau pressure 20 cmH2O• FIO2 50%
Anticoagulated
ECMO: Does it work?75 matched pairs with H1N1 induced ARDS found
that referral and transfer to an ECMO center was associated with lower hospital mortality (23.7 versus 52.5 percent)
(JAMA. 2011;306(15):1659)
Efficacy and economic assessment of conventional ventilatory support versus extracorporeal membrane oxygenation for severe adult respiratory failure (CESAR): a multicentre randomised controlled trial.
(Lancet 2009;374(9698):1351)n=90 each groupECMO group 68 (75%) received ECMO
63% no disability at 6 monthsConventional group
47% no disability at 6 months
Mechanical Ventilation in ARDS
• High ventilating pressures cause ventilator induced lung injury
• Lung Protective Ventilation• Low VT improves mortality
• Meta-analysis 6 trails (n=1297)• 6 ml/kg vs 12 ml/kg• 28 day mortality 27% vs 37%
(Ann Intern Med 2009;157:566)
Mechanical Ventilation: ARDS
Low Tidal Volume VentilationSlowly drop VT to 6 ml/kg IBW and maintain Pplat ≤ 30 cmH2O
(Plateau)
Mechanical Ventilation: ARDS
Low Tidal Volume VentilationPermissive Hypercapnia• PaCO2 increases to keep pH ≥
7.25• PEEP to keep lung open and
minimize cyclic atelectasis (8-16 cmH20)
• Goal to drop FIO2 ≤ 60% before decreasing PEEP and increasing VT
• Consider recruitment maneuvers
ARDS: Prone Positioning
Improves ventilation/perfusion matching
Oxygenation and Proning
ARDS: Prone Positioning
Multicenter randomized trial• Prone > 16 hours/day vs supine
(n=230/group)
Severe ARDS PaO2/FIO2 <150 mmHg• Lung protective ventilation
– VT 6 ml/kg, Pplat < 30 cmH2O, pH > 7.2
– Ventilated < 36 hours• Primary endpoint 28 day
mortalityN Engl J Med. 2013;368(23):2159
N Engl J Med. 2013;368(23):2159
16% (p < 0.001)
38%28 Day mortality
ARDS: Adjunctive/Novel Therapy
Inhaled VasodilatorsSelectively dilate vessels in well ventilated lung zones and improve oxygenation by improved V/Q matching. Also improve pulmonary hypertension
ARDS: Inhaled Vasodilators
Inhaled Prostacyclin (Epoprostenol,Flolan™)• Nebulized in inspiratory line• Vary strength• No sophisticated equipment• Improves oxygenation, not mortality
ARDS: Inhaled Vasodilators
Nitric Oxide• Requires specialized system• Byproduct nitrogen dioxide highly toxic • oxygenation
ARDS: Adjunctive/Novel Therapy
Surfactant• Rationale: prevent atelectasis• No conclusive data in adults• Some positive data infants and
children
Antioxidants (dietary oils)• Rationale: reactive oxygen species
and partial depletion of antioxidant defense appear important in propagation of ARDS
• A few early trial promising• Recent trials negative, more ongoing
ARDS: Adjunctive/Novel Therapy
High Frequency Ventilation• Rationale: benefit of low VT ventilation
known• f > 60 and VT smaller than dead space • Used after 3 days of hypoxemia• Clinical expertise critical• Used in infants
ARDS: Adjunctive/Novel Therapy
Glucocorticoids (steroids)• Ongoing controversy: trials both
positive and neutral• Likely most helpful early and
should not be initiated after 14 days (after fibroproliferative phase of disease)
ARDS: Patient Outcome
Mortality ≅ 25-30%Psychiatric: PTSD, depression,
anxiety 30-60% at one yearPhysical: abnormal exercise
test 66% at 1 and 3 years Pulmonary: most patients 80%
predicted by 6 months
And to think we complained about hand hygiene!
Doctors without Borders: West Africa