Answers:

Question 1

PH = 7.47 so we have alkalaemia

PCO2 = 27, the primary process is Respiratory Alkalosis.

Then we need to check for compensation… From the presentation, the condition looks acute.  For acute respiratory alkalosis, HCO3 drops by 2 for every 10 that PCO2 less than 40.

 Expected HCO3 = 24 – {(40 – PCO2)/ 10} x 2. Accordingly expected HCO3 = 24 – {(40 – 27)/10 x 2 = 21.4.

21.4 is greater than 16, do we have additional metabolic acidosis.

With metabolic acidosis we need to calculate the anion gap. That is: Na – ( Cl + HCO3 ) = 22.  So it is high anion gap metabolic acidosis.

Anion gap should be corrected to the level of Albumin.

 Corrected anion gap = measured anion gap + {0.25 x (40 – Albumin level)}. So, corrected anion gap = 25.25

Next step is to calculate the delta ratio. That is (AG – 12)/ (24-HCO3), so we have (25-12)/ (24- 16) = 16. So we have a pure high anion gap metabolic acidosis (ratio between 0.8 – 2 = HAGMA).

So we have Acute respiratory alkalosis associated with high anion gap metabolic acidosis.

After interpreting blood gases we need to create a differential diagnosis.

For Respiratory Alkalosis, we follow the mnemonic (CHAMPS).

 C = CNS causes

 H = Hypoxia (pulmonary causes).

 A = Anxiety or Pain

 M = Mechanical ventilation

  S = Salicylate or sepsis.

 From the history above, the patient is hypoxic. So pulmonary causes are on the top of the list (pneumonia).

For HAGMA we follow the mnemonic (CAT MUDPILES) or for practical reasons we can use (Left Total Knee Replacement).

 L = Lactate

 T = Toxin

 K = Ketones

 R = Renal.

 Lactate was elevated, slightly elevated urea, Glucose level was normal, Toxin (very unlikely).

High lactate represent poor tissue perfusion which is systemic in this case due to a shock state.

This patient has Septic shock (sepsis induced hypotension) secondary to pneumonia.

Question 2,

management of the case.

We have a very unwell old lady from a nursing home with septic shock secondary to pneumonia.

 Being an elderly woman from a nursing home we need to establish ceiling of care for her.

 For septic shock. We follow the goals of sepsis management.

1. Early recognition and intervention.

Patient is unwell, she needs to be moved to a resuscitation bed with full monitoring capacity.

• Appropriate broad spectrum antibiotics (within 1 hour)
• Aggressive haemodynamic resuscitation with fluids (start with crystalloids up to 30 ml/kg).
• Monitoring for:
• Blood pressure (aim for MAP> 65) – preferably through artline
• Lactate clearance
• Urine output (aim for > 0.5 ml/kg/hr)
• CVP (aim for 8-12)

 This patient has high CURB – 65 score (5), mortality rate around 27%. She is already hypoxic; her condition is expected to get worse next day before it starts to get better. This patient needs admission to ICU (If she is for full management). 5