A 64-year-old female patient is admitted to ICU following lung volume reduction surgery for bullous emphysematous lung disease. She is an ex-smoker with 40 pack year history, with a background history of hypertension and cor pulmonale. She was extubated post-procedure, prior to ICU admission. Her medications include amlodipine, frusemide, and bronchodilators. The following blood gas analysis was done on day 2 post-operative.
|Parameter||Patient Value||Adult Normal Range|
|pH||7.40||7.35 – 7.45|
|pO2||57 mmHg (7.6 kPa)|
|pCO2||64.0 mmHg (8.5 kPa)*||35.0 – 45.0 (4.6 – 6.0)|
|Bicarbonate||39.0 mmol/L*||22.0 – 26.0|
|Base Excess||12.3 mmol/L*||-2.0 – +2.0|
|Lactate||0.8 mmol/L||0.5 – 1.6|
|Sodium||134 mmol/L*||135 – 145|
|Potassium||4.4 mmol/L||3.5 – 5.0|
|Chloride||101 mmol/L||95 – 105|
|Glucose||7.7 mmol/L*||3.5 – 6.0|
Let us dissect these results systematically:
So. This is a double disorder, a metabolic alkalosis as well as a respiratory acidosis. This heavy smoker has just had some of her gas exchange surface removed, and is under the effects of opiates following surgery, which explains this underwhelming respiratory performance. The metabolic alkalosis could be explained by some degree of chronic renal adaptation to hypercapnia, as well as the effects of long-term frusemide therapy.