Question

49 years severe COPD, who is on 4 liters nasal cannula home oxygen with pulse oximetry and who has OSA on BiPAP at night. Patient’s medical history is CAD (coronary artery disease), DM2, HTN, HLD, history of tobacco use. Last night, her oxygen saturation dropped to the mid 60’s and has used her nebulizer with albuterol and albuterol MDI about 30 times in the past 24 hours. She has a productive cough, shortness of breath, use of accessory muscles and is wheezing, the sputum is thick white. The patient then decided to come to the emergency room. Once the patient was in the ED, she became obtunded and the following laboratory results were obtained:

Ht: 6 feet 1 inch

WBC: 10.2                                            7.26/>80/102/37.9/7.9/95% on 70% High flow aerosol mask

RBC 4.51

Hgb 13.8

Hct 42.5%

Platelets: 135

Na: 134

K: 3.9

Total CO2: 38

BUN: 27

Creatinine: 1.0

Glucose: 130

1-Calculate the A-a gradient? Based on the result of the A-a gradient, what does it tell you about your patient?

2-Make specific recommendations for treatment of this patient

Answer 1

1-Calculate the A-a gradient? Based on the result of the A-a gradient, what does it tell you about your patient?

Given patient ABG values- PH-7.26/PaO2-80/ PaCO2-102/37.9/7.9/ spo2 -95% on 70% High flow aerosol mask

A-a gradient = PAO2 - PaO2

PAO2 = ( FiO2 * (Patm - PH20)) - (PaCO2 / 0.8)

PAO2 = ( FiO2 * (760 - 47)) - (PaCO2 / 0.8) ,here Patm and PH2O are constant values 760 and 47 respectively.

PAO2 = ( 0.7* (760 - 47)) - (102 / 0.8)=499.1-127.5=371.6mmhg

A-a gradient = PAO2 - PaO2=371.6mmhg-80mmhg=291.6mmhg

Normal A-a gradientfor for a 49 year old patient =(Age in years/4)+4=16.25mmhg.

Here this patients A-a gradient is very high indicating severe hypoxemia related to the exacebration of COPD.

Recommendations for this patient treatment:

Aims on washing out of Co2 and treating hypoxia.

Sugggest to keep the patient on Non invasive ventilation(BIPAP) with a settings of IPAP 14 to EPAP 8 and FIO2-70%.

Abg to be repeated after an hour of NIV application and adjust the settings accordingly if not improving with pco2,need to consult physician for the need of invasive ventilation.

Nebulizations should be continued as per physician recomendation.

continous monitoring of saturation is recomended to keep saturation above 92%.