# Lab case 388

46-year-old female patient presented with few episodes of vomiting. Her VBG showed the following:

PH = 7.55

pCO2 = 26 mmHg

# Lab case 387 Interpretation

Question 1:

pH = 7.357, that is within the normal range, towards the acidotic side.

HCO3 = 16.2, that is low. So, we have metabolic acidosis

Next, we need to calculate the compensation and the Anion Gap for this patient.

We use Winter’s formula to get the expected pCO2 that is:

Expected pCO2 = 1.5 x HCO3 +8 (+/- 2). That will give us expected pCO2 of 32.3 (30.3 – 34.3). Here, it can be mild respiratory component, or it is normal as the sample was venous. (We need to get an arterial sample to find out the correct answer for that).

Anion Gap = Na – (Cl+HCO3) = 11 (normal)

So, we have normal anion gap metabolic acidosis NAGMA.

Other abnormal findings:

Na = 127, that is moderate hyponatraemia. However, this patient had high glucose level. High glucose cause pseudohyponatraemia.

To calculate the corrected Na level we use the following formula.

Corrected Na = Measured Na + (Glucose – 5)/3 = 130 mmol/L. That puts Na level for this patient in the mild range.

Hyperkalaemia

Severe hypocalcaemia

High glucose (no ketones given, normal anion gap)

These biochemical features are consistent with multiple endocrine dysfunction:

Addison’s disease (low Na, high K, NAGMA)

Uncontrolled Diabetes (check ketones)

Hypocalcaemia

Check Thyroid function (very fast HR)

However, it is important to consider sepsis as a cause. (hypotension, tachycardia, diarrhoea. features on history are suggestive. However, lactate is normal

1. Examination Features:

(a) Source of infection – thorough head to toe examination, including ENT, chest, abdomen. CXR and UA immediately

(b) Severity of sepsis/ complications – GCS, perfusion, Urine output, Ileus,,, etc.

(c) Features of Addison’s – weight loss, hyperpigmentation

In general, some features of Addison’s include:

• Muscle weakness and fatigue
• Weight loss and decreased appetite
• Darkening of your skin (hyperpigmentation)
• Low blood pressure, even fainting
• Salt craving
• Low blood sugar (hypoglycemia)
• Nausea, diarrhea or vomiting
• Muscle or joint pains
• Irritability
• Depression
• Body hair loss or sexual dysfunction in women

(d) Features of hypocalcaemia

“CATS go numb”- Convulsions, Arrhythmias, Tetany and numbness/parasthesias in hands, feet, around mouth and lips.

• Petechiae, purpura
• Oral, perioral and acral paraesthesia (early symptom)
• Carpopedal and generalized tetany
• Latent tetany
• Trousseau’s sign
• Chvostek’s sign
• Tendon reflexes are hyperactive
• Life-threatening complications
• Laryngospasm, brochospasm
• Cardiac arrhythmias
• Effects on cardiac output
• Positive chronotropy
• Negative inotropy effect
• ECG – Intermittent QT prolongation – high risk of TdP

Chronic hypocalcaemia – poor dentition, cataracts, papilloedema, ectopic calcification, dementia

(e) Complications of Diabetes:

Retinopathy

Neuropathy

Renal impairment….. etc

1. Treatment Priorities

Full cardiac monitoring, serial ECG’s, defib pads applied

Resuscitation – as per surviving sepsis – fluids, antibiotics (source control), other – inotropes, monitor response to treatment

Replace Calcium – 10 mls of 10% Ca Gluconate IV

Steroids – hydrocortisone 200 mg IV

Insulin Infusion  (2-4 units/hr)- aim to correct ketoacidosis if present and correct glucose gradually over 2-4 hours

# Lab case 387

A 27-year-old female presented with fever, diarrhoea and feeling unwell for 3 days.  Her vitals showed the following:

Blood pressure = 102/50 mmHg

Pulse rate = 138/min

# Lab case 386

85 years old lady with history of COPD, brought to ED with low GCS after VF cardiac arrest followed by return of spontaneous circulation after 3 minutes of CPR and a single DC shock. Her VBG on arrival showed:

PH = 7.222

# Lab case 385 interpretation

Question 1:

PH = 7.344, that is mild acidaemia.

HCO3 = 18.4 mmol/L (less than 24). So, we have metabolic acidosis.

# Lab case 385

21-year-old girl with history of type I DM. Her BSL level at home was 37 mmol/L. So, she self-administered 10 units of Actrapid. She rechecked her BSL 1 hour later and it was 38 mmol/L so she decided to present to ED. On arrival to ED her VBG showed the following:

# Lab case 384 interpretation

Question 1

PH = 7.47 that is mild alkalaemia.
HCO3 = 39.2 accordingly we have metabolic alkalosis
Next compensation: expected PCO2 = 0.7 x HCO3 + 20 (range: +/- 5).
0.7 x 39.2 + 20 = 47.4 (Range 42.7 to 52.7).
PCO2 is 57, that is higher than the expected PCO2 so we have additional respiratory acidosis.

# Lab case 384

30 year-old-lady sent by her GP for increasing tiredness over the last few months. She has been under too much stress, due to increasing work demands and hers wedding planning.

Her blood gases (Venous) showed the following:

PH = 7.47

PCO2 = 57 mmHg

# Lab case 383 interpretation

Question 1:

Ph = 7.549, that is alkalaemia.

pCO2 = 24.1 mmHg, then it is respiratory alkalosis.

Next, we will calculate the compensation. From the story, the condition is acute. For acute respiratory alkalosis we expect HCO3 to drop by 2 for every 10 pCO2 less than 40.