Lab Case 216 Interpretation

50 year old diabetic presents with abdominal pain and hiccups


Respiratory alkalaemia pH 7.538 pCO2 20

Compensation – Expected HCO3 = for every 10 decrease in CO2 HCO3 decreases by 2 =22mmol/l

AG= Na –(Cl+HCO) =20

Delta Ratio = Change in AG/Change in HCO3 = 1.1

The above VBG shows a mixed respiratory alkalaemia with an underlying metabolic acidaemia secondary to a HAGMA. There is a markedly elevated glucose and a mildly elevated lactate, with a normal creatinine and electrolytes.

In this clinical context the HAGMA is most likely due to an underlying DKA. However the ingestion of salicylates will give a similar picture – combined respiratory alkalosis and metabolic acidosis. A rare cause for respiratory alkalosis is persistent hiccupping.  In the context of DKA another cause of respiratory alkalosis is cerebral oedema, a complication of the treatment of DKA. The patients abdominal pain could also cause him to hyperventilate.

Causes of persistent hiccups:

1. CNS – CVA, Neoplasms, infections

2. Vagus and phrenic nerve irritation – goitre, neck cyst or tumours, TM foreign bodies, chest causes below

3. Thoracic – enlarged lymph nodes, infections, mediastinal tumours or infections, aortic aneurysm, MI, myocarditis

4. Metabolic – hyperglycaemia, hyponatraemia, hypocalcaemia, uraemia, hypocarbia, alcohol

5. Drugs – barbituates, benzo’s, methyldopa, dexamethasone, chemotherapy

6. Post op – gastric distention, neck traction, anaesthetic related, traction on viscera

7. Psychogenic – stress, conversion disorder, malingering, anorexia

Treatment of persistent hiccups

  • Treat underlying cause
  • Pharmacological treatment :

Chlorpromazine – only medication with FDA approval for treatment of persistent hiccups

Other drugs that can be used -gabapentin, metoclopramide, baclofen. Benzo’s should be avoided as they exacerbate hiccups

  • Non pharmacological treatment – vagal stimulation (carotid massage, ocular globe pressure, Valsalva), direct pharyngeal stimulation by oral or nasal catheter, direct uvula stimulation, C3-5 dermatome stimulation. Lots of other reported ways.
  • Surgical intervention in extreme cases with Phrenic nerve ablation