PH = 7.599 That is moderate alkalaemia (very close to the severe range – Moderate alkalaemia is PH between 7.5 – 7.6. Severe alkalaemia is PH > 7.6).
PCO2 = 22 mmHg, that is low. So we have respiratory alkalosis.
Next step is compensation.
42 year old alcoholic man, with type 2 DM. Presented with alcohol withdrawal symptoms. His blood gas (VBG) showed the following:
PH = 7.599
PCO2 = 22 mmHg
PH = 7.24 that is moderate acidaemia.
HCO3 = 16 mmol/L, so we have metabolic acidosis.
Next, we need to calculate the anion gap and the compensation.
54-year-old asthmatic patient presented with multiple episodes of vomiting. Her pulse-rate was 110 and blood pressure was 96/54. Her blood gases showed the following:
PH = 7.24
pCO2 = 33 mmHg
PH = 7.32 ( less than 7.35) so, we have mild acidaemia.
PCO2 = 48 mmHg ( on arterial blood gas > 40), so we have respiratory acidosis.
Next step, is to calculate the metabolic compensation. Since the condition is acute, we expect the HCO3 to increase by 1 for every 10 PCO2 above 40. Accordingly, expected HCO3 is 24.8. That is very close to 24. So there is no additional metabolic process.
Mild lactataemia which can be attributed to dehydration or salbutamol therapy. K = 3.4 (can be also related to salbutamol therapy).
Respiratory acidosis in asthma is a critical situation (severe/ life threatening asthma – even if the acidosis is mild).
This patient should be moved to a resuscitation bay, we should inform the emergency consultant and ICU team. Request the help of anaesthetic team for fast rapid intubation.
Start treatment immediately. (Hit it hard and hit it fast), our aim is to prevent intubating this patient.
- Continuous nebulized salbutamol and add nebulized ipratropium using 15L O2.
- Obtain 2 IV accesses and administer hydrocortisone immediately. The literature does not support the use of high dose corticosteroids in acute asthma. Hydrocortisone 50 mg 4 times a day for 48 hours, followed by oral prednisone, was as effective as 200 mg or 500 mg of hydrocortisone followed by high dose prednisone. The effective dose of oral prednisolone is between 30 mg and 50 mg daily. High doses of corticosteroids are associated with increased adverse effects, in particular mood disturbance and myopathy.
- Start IV magnesium in one line, (Rowe BH et al, Cochrane review)- MgSO4 for Treating Exacerbation of Acute Asthma in ED- 665 patients (7 trials). The conclusion was: MgSO4 would seem to have limited benefit in non-severe asthma and dramatic effect in the severe subgroup with NNT=3 ( preventing 1 admission in 3 cases). SO, use MgSO4 early in severe asthma.
- Start IV salbutamol in the other line
- Non invasive ventilation (CPAP vs BiPAP). Systemic review of 492 articles identified from the database search, the conclusion was more research is required. However, BiPAP had better effect on improving the work of breathing for patient with severe asthma.
Non-invasive ventilation in severe asthma help to:
- Reduce airways resistance
- Counter Atelectasis
- reduce work of breathing
- help to deliver medication to distal tubules
- reduce the cardiovascular impact of changes in intrapleural and intrathoracic pressure.
Ultimately, NIV in asthmatic patient help in the correction of PH and improves ventilation at a lower pressure than that needed for mechanical ventilation and it reduced the need for intubation.
- PEEP = 3-5 (Low)
- iPAP = 7-15
- High I:E ratio (1:5) with prolonged expiratory time
- Target RR < 25
If the above measures fail then we need to proceed to intubate this patient. For intubation, we use Ketamine as the sedating agent and the intubation should be performed by the most experienced doctor available.
Question 1 answer:
PH = 7.315, that is mild acidaemia.
pCO2 = 48 mmHg. For venous blood, pCO2 level up to 48 mmHg is considered normal (40 for arterial blood).
Volume = 15 ml. Still significant, Normal amount of synovial fluid in a knee joint is 0.5 to 4 mls. Knee joint can accommodate volume to about 100 ml.
32 year old man presented with right knee pain and swelling. He also complained of UTI that didn’t respond to Cephalexin and Augmentin. His Synovial fluid analysis revealed the following:
Volume of 25 ml is large, normal amount of synovial fluid in a knee joint is 0.5 to 4 ml. This indicates effusion. The knee joint is one of the largest joints in the body and it can accommodate around 100 ml of synovial fluids in cases of massive severe effusion.
That tells us that there is abnormal amount of fluid in the joint but it doesn’t help in detecting the cause.
30 year old man presented with right knee pain and swelling. Synovial fluid analysis revealed the following:
Volume 25 ml
Description: Turbid yellow