Updated: 11/24/2017

Acute Respiratory Distress Syndrome (ARDS)

Topic
Review Topic
0
0
Questions
5
0
0
Evidence
5
0
0
Videos
2
Snapshot
  • A 46-year-old woman is admitted to the ICU with severe pancreatitis. During the first 24 hours of admission, severe hypoxemia that requires ventilatory support with high concentrations of inspired oxygen develop. On exam the patient has rhonchi and crackles bilaterally. An arterial blood gas collected at 60% FiO2 reveals pH 7.42, PCO2 35 mmHg, and PO2 108 mmHg.
Introduction
  • Defined as acute diffuse, inflammatory lung injury leading to increased vascular permeability, increased lung weight and loss of aerated lung tissue   
    • hyperactivation of coagulation and/or inflammation damages both type I and II pneumocytes
      • ↓ type II pneumocytes results in ↓ surfactant production
      • ↓ surfactant production results in low lung compliance and subsequent atelectasis
    • repair often results in interstitial fibrosis
  • Causes
    • infection
      • pneumonia
      • sepsis
        • typically gram-negative sepsis
    • aspiration
    • acute pancreatitis
    • trauma with shock
    • amniotic fluid embolism (rare)
    • uremia
Presentation
  • Symptoms
    • dyspnea
  • Physical exam
    • tachypnea
    • bilateral rales and decreased breath sounds
Evaluation
  • Arterial blood gas
    • severe hypoxemia on pulse oximetry and ABG
      • may not be responsive to 100% O2
      • atelectasis results in intrapulmonary shunting
  • Radiology
    • diffuse, bilateral alveolar infiltrates on CXR
    • ground glass opacities and consolidations on chest CT often with dependent lung predominence
  • Histology 
    • diffuse alveolar damage
    • protein-rich leakage (exudate) forming an intra-alveolar hyaline membrane
  • Severity graded on PaO2 / FiO2 ratio and required PEEP (see below)
Treatment
  • Respiratory support & treat underlying cause
    • Mechanical ventilation with low tidal volume (4-6 mL/kg ideal body weight) 
    • PEEP (positive end-expiratory pressure)
      • prevents airway collapse at end-expiration
      • recruits collapsed alveoli
        • increases FRC and decreases shunting
 

Please rate topic.

Average 4.9 of 8 Ratings

Thank you for rating! Please vote below and help us build the most advanced adaptive learning platform in medicine

The complexity of this topic is appropriate for?
How important is this topic for board examinations?
How important is this topic for clinical practice?
Questions (5)
Lab Values
Blood, Plasma, Serum Reference Range
ALT 8-20 U/L
Amylase, serum 25-125 U/L
AST 8-20 U/L
Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL
Calcium, serum (Ca2+) 8.4-10.2 mg/dL
Cholesterol, serum Rec: < 200 mg/dL
Cortisol, serum 0800 h: 5-23 μg/dL //1600 h:
3-15 μg/dL
2000 h: ≤ 50% of 0800 h
Creatine kinase, serum Male: 25-90 U/L
Female: 10-70 U/L
Creatinine, serum 0.6-1.2 mg/dL
Electrolytes, serum  
Sodium (Na+) 136-145 mEq/L
Chloride (Cl-) 95-105 mEq/L
Potassium (K+) 3.5-5.0 mEq/L
Bicarbonate (HCO3-) 22-28 mEq/L
Magnesium (Mg2+) 1.5-2.0 mEq/L
Estriol, total, serum (in pregnancy)  
24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL
28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL
Ferritin, serum Male: 15-200 ng/mL
Female: 12-150 ng/mL
Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL
Female: premenopause: 4-30 mIU/mL
midcycle peak: 10-90 mIU/mL
postmenopause: 40-250
pH 7.35-7.45
PCO2 33-45 mmHg
PO2 75-105 mmHg
Glucose, serum Fasting: 70-110 mg/dL
2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation Fasting: <5 ng/mL
Provocative stimuli: > 7ng/mL
Immunoglobulins, serum  
IgA 76-390 mg/dL
IgE 0-380 IU/mL
IgG 650-1500 mg/dL
IgM 40-345 mg/dL
Iron 50-170 μg/dL
Lactate dehydrogenase, serum 45-90 U/L
Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL
Female: follicular phase: 5-30 mIU/mL
midcycle: 75-150 mIU/mL
postmenopause 30-200 mIU/mL
Osmolality, serum 275-295 mOsmol/kd H2O
Parathyroid hormone, serume, N-terminal 230-630 pg/mL
Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L
Phosphorus (inorganic), serum 3.0-4.5 mg/dL
Prolactin, serum (hPRL) < 20 ng/mL
Proteins, serum  
Total (recumbent) 6.0-7.8 g/dL
Albumin 3.5-5.5 g/dL
Globulin 2.3-3.5 g/dL
Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL
Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h
Thyroxine (T4), serum 5-12 μg/dL
Triglycerides, serum 35-160 mg/dL
Triiodothyronine (T3), serum (RIA) 115-190 ng/dL
Triiodothyronine (T3) resin uptake 25%-35%
Urea nitrogen, serum 7-18 mg/dL
Uric acid, serum 3.0-8.2 mg/dL
Hematologic Reference Range
Bleeding time 2-7 minutes
Erythrocyte count Male: 4.3-5.9 million/mm3
Female: 3.5-5.5 million mm3
Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/h
Female: 0-20 mm/h
Hematocrit Male: 41%-53%
Female: 36%-46%
Hemoglobin A1c ≤ 6 %
Hemoglobin, blood Male: 13.5-17.5 g/dL
Female: 12.0-16.0 g/dL
Hemoglobin, plasma 1-4 mg/dL
Leukocyte count and differential  
Leukocyte count 4,500-11,000/mm3
Segmented neutrophils 54%-62%
Bands 3%-5%
Eosinophils 1%-3%
Basophils 0%-0.75%
Lymphocytes 25%-33%
Monocytes 3%-7%
Mean corpuscular hemoglobin 25.4-34.6 pg/cell
Mean corpuscular hemoglobin concentration 31%-36% Hb/cell
Mean corpuscular volume 80-100 μm3
Partial thromboplastin time (activated) 25-40 seconds
Platelet count 150,000-400,000/mm3
Prothrombin time 11-15 seconds
Reticulocyte count 0.5%-1.5% of red cells
Thrombin time < 2 seconds deviation from control
Volume  
Plasma Male: 25-43 mL/kg
Female: 28-45 mL/kg
Red cell Male: 20-36 mL/kg
Female: 19-31 mL/kg
Cerebrospinal Fluid Reference Range
Cell count 0-5/mm3
Chloride 118-132 mEq/L
Gamma globulin 3%-12% total proteins
Glucose 40-70 mg/dL
Pressure 70-180 mm H2O
Proteins, total < 40 mg/dL
Sweat Reference Range
Chloride 0-35 mmol/L
Urine  
Calcium 100-300 mg/24 h
Chloride Varies with intake
Creatinine clearance Male: 97-137 mL/min
Female: 88-128 mL/min
Estriol, total (in pregnancy)  
30 wks 6-18 mg/24 h
35 wks 9-28 mg/24 h
40 wks 13-42 mg/24 h
17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 h
Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total Male: 8-20 mg/24 h
Female: 6-15 mg/24 h
Osmolality 50-1400 mOsmol/kg H2O
Oxalate 8-40 μg/mL
Potassium Varies with diet
Proteins, total < 150 mg/24 h
Sodium Varies with diet
Uric acid Varies with diet
Body Mass Index (BMI) Adult: 19-25 kg/m2
Calculator

Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK

(M1.PL.23) A 45-year-old man arrives by ambulance to the emergency room after being involved in a very severe construction accident. The patient was found unconscious with a large metal spike protruding from his abdomen by a coworker who was unable to estimate the amount of time the patient went without medical aid. Upon arrival to the ER, the patient was unconscious and unresponsive. His vital signs are BP: 80/40, HR: 120 bpm, RR: 25 bpm, Temperature: 97.1 degrees, and SPO2: 99%.He is taken to the operating room to remove the foreign body and control the bleeding. Although both objectives were accomplished, the patient had an acute drop in his blood pressure during the surgery at which time ST elevations were noted in multiple leads. This resolved with adequate fluid resuscitation and numerous blood transfusions. The patient remained sedated after surgery and continued to have relatively stable vital signs until his third day in the intensive care unit, when he experiences an oxygen desaturation of 85% despite being on a respirator with 100% oxygen at 15 breaths/minute. On auscultation air entry is present bilaterally with the presence of crackles. A 2/6 systolic murmur is heard. Readings from a Swan-Ganz catheter display the following: central venous pressure (CVP): 4 mmHg, right ventricular pressure (RVP) 20/5 mmHg, pulmonary artery pressure (PAP): 20/5 mmHg. Pulmonary capillary wedge pressure (PCWP): 5 mm Hg. A chest x-ray is shown as Image A. The patient dies soon after this episode. What is the most likely direct cause of his death? Review Topic

QID: 104029
FIGURES:
1

Diffuse alveolar damage

38%

(3/8)

2

Ventricular septal defect

0%

(0/8)

3

Myocardial free wall rupture

12%

(1/8)

4

Papillary muscle rupture

50%

(4/8)

5

Myocardial reinfarction

0%

(0/8)

M1

Select Answer to see Preferred Response

PREFERRED RESPONSE 1

(M1.PL.96) A 48-year-old female suffers a traumatic brain injury while skiing in a remote area. Upon her arrival to the ER, she is severely hypoxemic and not responsive to O2 therapy. She is started on a mechanical ventilator and 2 days later upon auscultation, you note late inspiratory crackles. Which of the following is most likely normal in this patient? Review Topic

QID: 100899
1

Type I pneumocytes

9%

(1/11)

2

Type II pneumocytes

36%

(4/11)

3

Chest X-ray

0%

(0/11)

4

Alveolar-arterial gradient

9%

(1/11)

5

Left atrial pressure

36%

(4/11)

M1

Select Answer to see Preferred Response

PREFERRED RESPONSE 5

(M1.PL.112) A 58-year-old male is hospitalized after sustaining multiple fractures in a severe automobile accident. Soon after hospitalization, he develops respiratory distress with crackles present bilaterally on physical examination. The patient does not respond to mechanical ventilation and 100% oxygen and quickly dies due to respiratory insufficiency. Autopsy reveals heavy, red lungs and histology is shown in Image A. Which of the following is most likely to have been present in this patient shortly before death: Review Topic

QID: 100915
FIGURES:
1

Diaphragmatic hypertrophy

0%

(0/23)

2

Proliferation of bronchiolar mucous glands

0%

(0/23)

3

Interstitial edema

52%

(12/23)

4

Large pulmonary embolus

39%

(9/23)

5

Left apical bronchoalveolar carcinoma

0%

(0/23)

M1

Select Answer to see Preferred Response

PREFERRED RESPONSE 3
ARTICLES (5)
VIDEOS (2)
Topic COMMENTS (14)
Private Note