Joyce Johnsrud, PGY-2

ACD 09.22.14

Case

*~60 yo woman presents in septic shock from pyelonephritis. Initially gets volume resuscitated, abx, and norepinephrine at 10 but doing ok on RA.

Imaging

On admission

*Hospital day 2 develops respiratory distress, so you get a CXR…

Hosp day 2 worsening SOA 7.23/34/53 on RA

HCO3 14; lactate 4.6

*Diagnosis?

*PaO2/FiO2 ratio?

7.23/34/53 on RA

*PaO2/FiO2 ratio?

*53 / 0.21 = 252

*Diagnosis?

* Acute Respiratory Distress Syndrome

*(more on this later)

HD 2, later that p.m., after diuresis

7.25/45/45 on 5L O2 NC HCO3 19

HD3 interval intubation

HD3 ABG 7.2/47/41 on 32/320/12/100

HD3 prone ABG 7.26/40/135 on 32/300/12/100

HCO3 23; Peak pressure 60

HD5 a.m. CXR

Diagnosis of new findings on this CXR?

HD5 a.m. CXR

Penumomediastinum

09/14

Acute respiratory distress syndrome

Berlin Criteria

*Acute Onset in setting of predisposing condition

*Bilateral infiltrates

*No evidence of left heart failure or fluid overload

*PaO2/FiO2 ≤ 300 mm Hg

*Mild PaO2/FiO2 200 to ≤ 300 mm Hg

*Moderate PaO2/FiO2 100 to ≤ 200 mm Hg

*Severe PaO2/FiO2 ≤ 100 mm Hg

Lung Protective Ventilation in ARDS* Initial VT = 8 mL/kg PBW at PEEP 5 cm H2O, FiO2 to achieve SpO2

88-95%

* Reduce VT by 1 mL/kg every 2 hours until at goal

* Then measure Ppl. If Ppl > 30 cm H2O, decrease VT by 1 mL/kg until at goal or VT = 4 mL/kg

* Respiratory acidosis

* If pH =7.15-7.30, increase RR until pH > 7.30 or RR = 35 bpm

* If pH < 7.15, increase RR to 35 bpm. If pH is still < 7.15, increase VT

by 1 mL/kg until pH > 7.15

* Permissive hypercapnia PaCO2 60-70 mm Hg and pH 7.2-7.25 safe for most patients

*Goals

*VT = 6 mL/kg PBW

*Ppl ≤ 30 cm H2O

*SpO2 = 88-95%

*pH = 7.30-7.45

Decreases Mortality and duration on vent

What about when that doesn’t work?

*Prone positioning

*Inhaled Nitric Oxide

*High Frequency Oscillatory Ventilation

*Extracorporeal membrane oxygenation

What about when that doesn’t work?

*Prone positioning- Physiology* Improves gas exchange, reduces V/Q mismatch

* Pleural pressure

* Supine: overinflation of the ventral alveoli and atelectasis of the dorsal alveoli which is exaggerated ARDS

* Prone: reduction in difference between the dorsal and ventral pleural pressures leading to more homogeneous ventilation

*Compression

* Supine: heart compresses the medial posterior lung and diaphragm compresses the posterior-caudal lung parenchyma worsening dependent lung collapse

* Prone: heart becomes dependent and diaphragm displaced, decreasing medial posterior compression, also improving cardiac output through increases in RV preload, decreased RV afterload due to recruitment and reduction in hypoxic pulmonary vasoconstriction

* Perfusion

Prone positioning*PROSEVA

* Guérin C, Reignier J, Richard JC, et al. Prone positioning in severe acute respiratory distress syndrome. N Engl J Med 2013; 368:2159.

*Multicenter, prospective, RCT of 466 patients with severe ARDS (PaO2/FiO2 <150 mmHg, FiO2 ≥0.6, PEEP ≥5 cm H2O) on low tidal volume mechanical ventilation

* Prone-positioning sessions of at least 16 hours vs supine Prone Supine

28-day mortality: 16% vs 33% [HR 0.39, 95% CI 0.25-0.63; p <0.001]

90-day mortality: 24% vs 41% [HR 0.44, 95% CI 0.29-0.67; p <0.001]

Ventilator Free days/28 days: 14 days

vs 10 days [p<0.001]

Successful extubation at 90 days: 81%

vs 65% [HR 0.45, 95% CI 0.29-0.70; p<0.001]

Pneumothorax: 6.3% vs 5.7% [HR 0.89, 95% CI 0.39-2.02]

Outcome:

Prone positioning*Limitations:

*1434 patients screened, 858 not eligible based on exclusion criteria

*Exclusion criteria lengthy

Prone positioning

•Use of NIV inhaled nitric oxide or almitrine bismesylate, or extracorporeal membrane oxygenation (ECMO) before inclusion.

Prone positioning*Limitations:

*1434 patients screened, 858 not eligible based on exclusion criteria

*Exclusion criteria lengthy

*Despite randomization, patients in supine group had higher SOFA scores, required more pressors and NM blocking agents

*Study site staff had extensive experience with prone ventilation

*Labor intensive, nutritional and nursing challenges

*Suggests mortality benefit of early, high-dose prone ventilation in a select population of severe ARDS who fail to improve with standard-of-care supine low tidal volume ventilation strategies when applied early after intubation but needs further validation

Inhaled Nitric Oxide

*Selective pulmonary vasodilator

*Increase flow to areas of high dead space ventilation

*Increase in arterial oxygenation is temporary- 1 to 4 days

*No assoc’d mortality benefit

*Adverse effects:

*Methemoglobinemia- rare

*Renal dysfunction (relative risk 1.59, 95% CI 1.17 to 2.16)

*Reserved for use in refractory hypoxemia

Supportive Care

*Sedation with daily wake up protocol

*Oral care

*Nutrition

*Elevated HOB

*DVT ppx

*GI ppx

Supportive Care*Fluid balance* Wiedemann, HP et al. Comparison of two fluid-management strategies in

acute lung injury. N Engl J Med. 2006;354(24):2564. NHLBI ARDS Clinical Trials Network

Conservative group Liberal group

Targeted CVP <4 mmHg or a pulmonary artery occlusion pressure (PAOP) <8 mmHg

Targeted CVP of 10 to 14 mmHg or a PAOP of 14 to 18 mmHg

Mean cumulative fluid balance was -136 mL

Mean cumulative fluid balance was +6992 mL

Ventilator free days 15 days

vs 12 days

ICU free days 13 days vs 11 days

60 day mortality rate unchanged

Supportive Care*Steroid therapy

*Early severe ARDS PaO2/FiO2 < 200 mm Hg on PEEP 5

* IV methylprednisolone 1 mg/kg/day x14 days; taper over next 14 days and discontinue

*Fibrinoproliferative phase of ARDS

* Risk of irreversible pulmonary fibrosis

*Occurs 7-14 days after onset

* IV methylprednisolone 2 mg/kg/day x14 days; 1 mg/kg/day x7 days; taper and discontinue at 2 wks post-extubation

*Risk of worsening glycemic control and prolonged neuromuscular weakness

References

*Guérin C, Reignier J, Richard JC, et al. Prone positioning in severe acute respiratory distress syndrome. N Engl J Med 2013; 368:2159.

*Wiedemann HP, Wheeler AP, Bernard GR, Thompson BT, Hayden D, deBoisblanc B, Connors AF Jr, Hite RD, Harabin AL. Comparison of two fluid-management strategies in acute lung injury. N Engl J Med 2006;354(24):2564.

*ARDS Network www.ardsnet.org

*uptodate.com

*Marino, Paul L. The ICU Book: Fourth Edition. New York: Lippincott, 2014.