Management of Acute Respiratory Distress Syndrome

2015 Winter Anesthesia Conference Management of Acute Respiratory Distress Syndrome Ronald Pearl, MD, PhD Professor and Chair Department of Anesthesi...
Author: Osborne Ward
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2015 Winter Anesthesia Conference

Management of Acute Respiratory Distress Syndrome Ronald Pearl, MD, PhD Professor and Chair Department of Anesthesiology Stanford University [email protected]

Disclosures • No financial disclosures

Learning Objectives • At the conclusion of the activity participants should be able to: – Discuss mechanisms of ventilator-associated lung injury and how appropriate ventilator management of the patient with ARDS can prevent such injury – Discuss fluid management of the patient with ARDS in the context of issues of systemic perfusion – Recognize complications associated with the use of high tidal volume, low PEEP ventilation in the operating room and the ICU

Intraoperative Ventilation in ARDS • Blum, Anesthesiology 2011; 115:75

U. Michigan database 2005-2009 8.7 ml/kg TV 5 cm PEEP FIO2 0.9 PIP ≈ 30 cm

Acute Respiratory Distress Syndrome • 23 year old woman involved in MVA – Bilateral chest contusions – Ruptured spleen – 15 units PRBC – Over next 2 days develops diffuse fever, tachycardia, bilateral infiltrates, hypoxemia on mechanical ventilation with 100% oxygen, increased bilirubin – What is the management and prognosis?

Acute Respiratory Distress Syndrome • 23 year old man involved in MVA – Bilateral chest contusions – Ruptured spleen – Massive transfusion in the ED – Over next 2 days develops diffuse fever, tachycardia, bilateral infiltrates, and hypoxemia – What is the management and prognosis?

ARDS • Which of the following interventions have been demonstrated to improve outcome in the patient with ARDS: – Tidal volume of 6 mL/kg – Fluid restriction – Pulmonary artery catheter monitoring – Inhaled nitric oxide – High dose steroids

ARDS • Ashbaugh, Lancet 1967;12;319 – 12 patients with tachypnea, hypoxemia, and decreased compliance following trauma, aspiration, or pulmonary infection – Improved oxygenation with PEEP – 60% mortality – Hyaline membrane formation on autopsy – “Adult respiratory distress syndrome”

American-European Consensus Conference (1994) • Acute lung injury – a syndrome of inflammation and increased permeability – cannot be explained by left atrial or pulmonary capillary hypertension – acute in onset and persistent

Acute Lung Injury and ARDS Timing

Chest Xray

Oxygenation

Acute

Bilateral infiltrates

PaO2/FIO2 < 300) at 6 hours (NNT = 3) – 27% vs. 54% transplanted

Effects of PEEP • Improved oxygenation – Decreased intrapulmonary shunting

• Decreased cardiac output – Decreased venous return – Increased PVR

• Variable effect on VALI – Decreased VALI due to prevention of cyclic collapse of alveoli – Increased VALI due to end-inspiratory overdistention of alveoli

How Should We Choose PEEP? • Patient develops severe ARDS – FiO2 0.80 – PEEP 14

• Will higher PEEP be of benefit?

Alveoli Study • Brower RG, N Engl J Med 2004;351:327 • Compared combinations of low PEEP/high FIO2 and high PEEP/low FIO2(n = 550) • PEEP: 9 ± 3.5 vs. 14.6 ± 3.6 • No difference in outcome

Meta-analysis of 3 trials

Briel, JAMA 2010;303:865

Intraoperative PEEP • Imberger, Cochrane Database Syst Rev 2010; CD007922. – 8 RCTs, 330 patients – Higher PaO2/FIO2 on POD 1 (+23) – Decreased postop atelectasis by CT scan – No significant effect on mortality (relative risk 0.95, 95% CI 0.14 to 6.39) – Mortality study would require 21,200 patients

Postoperative CPAP • Ferreyra, Ann Surg 2008; 247:617 – Meta-analysis of 9 RCT of postop CPAP – 34% decrease in postoperative pulmonary complications

How Do We Optimize Fluid Management? • • • • • • •

FiO2 0.80 PEEP 14 MAP 68 mm Hg CVP 8 mm Hg Urine output 15 ml/h Warm extremities with good capillary refill Should we place a PA catheter? Should we give fluid or dobutamine to optimize urine output?

Fluid Therapy and ALI • ARDSnet, NEJM 2006;354:2213 – 1000 patients with ALI – Randomized to CVP vs. PAC – Randomized to fluid restriction vs. liberal fluid strategy

Fluid Management Decisions • ARDSnet, NEJM 2006;354:2564 – First priority was management of hypotension – Fluid management then dependent upon two factors • Adequate urine output (≥ 0.5 ml/kg/h) • Presence of ineffective circulation –PAC group: CI < 2.5 L/min/m2 –CVP group: Cold, mottled extremities with slow capillary refill (> 2 seconds)

Target CVP Range Effective circulation with UOP ≥ 0.5 ml/kg/h

Effective circulation with UOP < 0.5 ml/kg/h

Ineffective circulation

Liberal

10-14

14-15

15-18

Conservative

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