Case Conference: Respiratory Failure Andrew M. Luks, MD Medicine 536 Introduction to Critical Care Medicine January 7, 2014

Case 1 46 year-old woman presented to the ED with a one week history of fevers, myalgias, headaches and nausea She had been seen the previous day in ER with similar complaints: –Nasal swab for influenza performed –Sent home on oseltamivir and acetaminophen

Case 1: Other History Past Medical History: –HIV (last CD4 count 63) –Prior history of crack lung Social History: –Lives with daughter; previously homeless –Daily cocaine use; (+) tobacco use Medications: –Antiretroviral therapy –TMP/SMX (Opportunistic infection prophylaxis) TMP/SMX: Trimethoprim / Sulfamethoxazole

Case 1: ED Presentation Vitals: T 35.4°C, BP 90/59, HR 127, RR 40 S p O 2 : 88% on non-rebreather mask Exam: –Ill-appearing; accessory muscle use –Crackles on lung exam bilaterally –Holosystolic murmur; neck veins normal –No peripheral edema Basic Labs: –WBC 2.6, Hematocrit 28% –Chem panel: BUN 15; Creatinine 1.1

Case 1 What studies would you order next?

Case 1: Her Arterial Blood Gas pH 7.46 PCO 2 23 PO 2 86 HCO 3 17 Base Deficit: 5.4 Done while on a non- rebreather mask (unknown F I O 2 ) How would you interpret the ABG?

Case 1: Chest Radiograph

Case 1 What is your differential diagnosis?

DDx: Hypoxemia and Diffuse Bilateral Opacities Cardiogenic pulmonary edema ARDS Acute interstitial pneumonitis Multilobar pneumonia Viral pneumonia Pneumocystis pneumonia Acute eosinophilic pneumonia Diffuse alveolar hemorrhage Acute hypersensitivity pneumonitis Cocaine-induced lung injury

Case 1 What additional diagnostic studies would you consider? What can you do to manage her respiratory failure?

Case 1: Other Laboratory Studies Troponin < 0.04 ng/mL Lactate 1.1 mmol/L Urine toxicology screen: positive for cocaine and opiates Urinalysis: –3+ occult blood –9-30 Red blood cells –2+ protein Sputum Gram’s stain: 4+ gram positive cocci

Case 1: What Happened Next

Case 1: Post-Intubation Chest Radiograph

Case 1 What should we do with the ventilator now? Her P a O 2 is only 65 mm Hg on an F I O 2 of 0.8 and a PEEP of 5

Case 1: Outcome

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Case 2 45 year-old man presents to the ED complaining of difficult swallowing and muffled speech for the past day Past Medical History: None Social History: active IV drug user (skin- popping); Non-smoker Review of Systems: denies dyspnea, fever, chills but notes problems with diplopia for the past day

Case 2: ED Presentation Vitals: T 37.2°C HR 90 BP 111/87 RR 11 Oxygen saturation: 88% breathing air Exam: –Difficulty keeping eyes open –Answers all questions appropriately, follows commands –Drooling; muffled speech –Lung and cardiac exam unremarkable –No lower extremity edema Vital Capacity: 40% predicted

Case 2: Skin Exam

Case 2 What studies would you order next?

Case 2: Arterial Blood Gas While Breathing Air pH 7.28 PCO 2 55 PO 2 71 HCO 3 28 Base Excess 2.8 How would you interpret the ABG?

Case 2: Chest Radiograph

Case 2 What should you do to manage his hypoxemia?

Why Does The Patient Have Ventilatory Failure? LoadAbility Decreased Drive Muscular Disorder Chest Wall Problem Peripheral Nerve Problem Source: Schmidt and Hall 1992 Increased V E Low Compliance High Resistive Load

Case 2 Should you intubate the patient or can you use non-invasive ventilation?

Signs of Bulbar Dysfunction Drooling / oral accumulation of saliva Weak cough Absent or impaired gag Nasal tonality to speech Cough / choke with food Nasal regurgitation These are often an indication for intubation

Contraindications to Non- invasive Ventilation Inability to protect airway or clear secretions Non-respiratory organ failure Facial surgery, trauma or deformity High aspiration risk Prolonged duration of support anticipated Recent esophageal surgery

Case 2: Diagnosis ?

Case 3 30 year-old man found unresponsive at home by his roommate The medics arrive and move to intubate the patient for altered mental status and absent gag reflex He is has a difficult airway and requires 3 attempts before intubation is successful He is transported to the HMC ED where he has an S p O 2 of 90% on F I O 2 1.0

Case 3: Chest Radiograph

Case 3: Arterial Blood Gas On F I O In The ICU pH 7.02 PCO 2 72 PO 2 55 HCO 3 18 Base Deficit 14.9 How would you interpret the ABG?

Case 3 Does hypoventilation explain all of his hypoxemia? Does he need to be on lung protective ventilation?

Case 3 How much shunt does this patient have?

Case 3 The patient is on a PEEP of 5 cm H 2 O with an F I O 2 of 1.0. Will raising the PEEP help his oxygenation?

The End Questions?