1–25

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Part 2 Cases 1–25

Case 1

History

A 25-year-old man, with no significant past medical history, presents to the emergency department with a 2-day history of fever, productive cough and worsening breathlessness.

Examination

He is hot and flushed with a temperature of 39.3°C. He does not appear distressed but is using accessory muscles of respiration. There is diminished chest expansion on the left with dullness to percussion, bronchial breathing and coarse crackles in the left lower zone posteriorly.

Pulse	104 beats/min
Respiratory rate	28 breaths/min
Blood pressure	118/70 mmHg
SaO₂ (room air)	89%

Arterial blood gas		On room air
23/7/2006
Unit no.: 00654545
ID: John Simpson		Normal
H⁺	31.8 nmol/L	(35–45)
pH	7.50	(7.35–7.45)
PCO_2d	3.74 kPa (4.7–6.0)
PCO_2d	28.1 mmHg	(35–45)
PO₂	7.68 kPa	(> 10.6)
PO₂	57.8 mmHg	(> 80)
Bicarb	23.9 mmol/L	(22–28)
BE	−0.5 mmol/L	(–2–+2)
SPO₂	88.7%	(> 98%)
Lactate	1.2	(0.4–1.5)
K	3.7 mmol/L	(3.5–5)
Na	138 mmol/L	(135–145)
Cl	99 mmol/L	(95–105)
iCa⁺	1.2 mmol/L	(1–1.25)
Hb	15 g/dL	(13–18)
Glucose	5.4 mmol/L	(3.5–5.5)

Questions

1. a) Describe his gas exchange.

b) Describe his acid–base status.

2. Should the patient receive supplemental O₂?

3. Is pulse oximetry a suitable alternative to repeated ABG monitoring in this case?

Case 2

History

A 34-year-old morbidly obese female with a body mass index of 49 has an ABG sample taken as part of her preoperative assessment for weight reduction surgery.

Apart from morbid obesity and type 2 diabetes, she is otherwise well and has no respiratory symptoms.

Arterial blood gas		On air
14/01/2005
Unit no.: 55392088
ID: Marcella Plantagenet
		Normal
H⁺	45 nmol/L	(35–45)
pH	7.35	(7.35–7.45)
PCO₂	7.3 kPa	(4.7–6.0)
PCO₂	54.8 mmHg	(35–45)
PO₂	9.6 kPa	(> 10.6)
PO₂	72.2 mmHg	(> 80)
Bicarb	29 mmol/L	(22–28)
BE	+3.8	(−2−+2)
SPO₂	96%	(> 98%)
Lactate	1	(0.4 – 1.5)
K	4.7 mmol/L	(3.5–5)
Na	134 mmol/L	(135–145)
Cl	102 mmol/L	(95–105)
iCa⁺	1.2 mmol/L	(1–1.25)
Hb	13 g/dL	(13–18)
Glucose	9 mmol/L	(3.5–5.5)

Questions

1. a) Describe her gas exchange.

b) Describe her acid–base status.

2. What is the most likely diagnosis?

Case 3

History

A 24-year-old female nursing student attends hospital complaining of sudden-onset breathlessness. She flew to the UK from Australia the previous day and is very concerned she may have a pulmonary embolism. She has no pleuritic pain, haemoptysis or leg swelling, no past history of lung disease or deep-vein thrombosis and is a non-smoker.

Examination

She appears anxious and distressed. Her respiratory rate is elevated but chest examination is unremarkable and there are no clinical signs of deep-vein thrombosis. A chest X-ray reveals no abnormalities.

Pulse	88 beats/min
Respiratory rate	22 breaths/min
Blood pressure	124/76 mmHg
SaO₂ (room air)	95%

23/7/2006
Unit no.: 00654545
ID: Jill Royds
		Normal
H⁺	31.2 nmol/L	(35–45)
pH	7.51	(7.35–7.45)
PCO₂	3.90 kPa	(4.7–6.0)
PCO₂	29.3 mmHg	(35–45)
PO₂	10.3 kPa	(> 10.6)
PO₂	77.0 mmHg	(> 80)
Bicarb	25.0 mmol/L	(22–28)
BE	+0.7 mmol/L	(−2−+2)
SpO₂	93.7%	(> 98%)
Lactate	1.0	(0.4 – 1.5)
K	4.3 mmol/L	(3.5–5)
Na	141 mmol/L	(135–145)
Cl	101 mmol/L	(95–105)
iCa⁺	1.2 mmol/L	(1–1.25)
Hb	13 g/dL	(13–18)
Glucose	4.6 mmol/L	(3.5–5.5)

Questions

1. a) Describe her gas exchange.

b) Describe her acid–base status.

2. What is the likeliest diagnosis?

Case 4

History

A 78-year-old male on a surgical ward is found unresponsive, having returned, a few hours previously, from a complicated open cholecystectomy.

Review of his charts reveals he has received three 10 mg injections of morphine since returning to the ward, in addition to the morphine delivered by his patient-controlled analgesia device.

Examination

The patient is unresponsive with shallow respirations and bilateral pinpoint pupils.

Pulse rate	90 beats/min
Respiratory rate	5 breaths/min
Blood pressure	98/64 mmHg
SaO₂	99%
BM	5.6 mmol/l

Arterial blood gas		On 28% O₂
18/09/2006
Unit no.: 6799986
ID: Henry Spasek
		Normal
H⁺	65.4 nmol/L	(35–45)
pH	7.18	(7.35–7.45)
PCO₂	8.2 kPa	(4.7–6.0)
PCO₂	62 mmHg	(35–45)
PO₂	11.76 kPa	(> 10.6)
PO₂	87 mmHg	(> 80)
Bicarb	22.4 mmol/L	(22–28)
BE	−1.5 mmol/L	(−2−+2)
SPO₂	99.8%	(> 98%)
Lactate	1	(0.4–1.5)
K	4.4 mmol/L	(3.5–5)
Na	137 mmol/L	(135–145)
Cl	103 mmol/L	(95–105)
iCa⁺	1.16 mmol/L	(1–1.25)
Hb	11 g/dL	(13–18)
Glucose	3.9 mmol/L	(3.5–5.5)

Questions

1. a) Describe his gas exchange.

Describe his acid–base status.

2. What is the most likely diagnosis?

3. What treatment does this patient require?

Case 5

History

A 75-year-old man is brought into the emergency department by his family. He is extremely short of breath and struggling to speak.

Following a conversation with his family it emerges that he has a long history of chronic obstructive pulmonary disease.

Over the last 3 days his breathing has worsened considerably and he has expectorated increased volumes of sputum.

Examination

The patient is struggling for breath and appears extremely distressed. He exhibits signs of chest hyperinflation and is breathing through pursed lips. Breath sounds are generally diminished but there are no added sounds.

Pulse	120 beats/min
Respiratory rate	26 breaths/min
Blood pressure	150/80 mmHg
Temperature	36°C
SaO₂%	81%

Arterial blood gas		On air
10/07/2005
Unit no.: 77655349
ID: Joseph Spielman
		Normal
H⁺	39.5 nmol/L	(35–45)
pH	7.40	(7.35–7.45)
PCO₂	4.9 kPa	(4.7–6.0)
PCO₂	36 mmHg	(35–45)
PO₂	5.8 kPa	(> 10.6)
PO₂	44 mmHg	(> 80)
Bicarb	23 mmol/L	(22–28)
BE	−1.2 mmol/L	(−2−+2)
SPO₂	80%	(> 98%)
Lactate	1.0	(0.4–1.5)
K	4.1 mmol/L	(3.5–5)
Na	137 mmol/L	(135–145)
Cl	99 mmol/L	(95–105)
iCa⁺	1.1 mmol/L	(1–1.25)
Hb	16.5 g/dL	(13–18)
Glucose	3.8 mmol/L	(3.5–5.5)

Questions

1. a) Describe his gas exchange.

b) Describe his acid–base status.

2. Should you provide him with oxygen?

Case 6

History

The patient from the previous case is treated in the emergency department with nebulised bronchodilators, oral prednisolone and antibiotics. He is then transferred to a respiratory ward where he is administered 28% oxygen by a fixed concentration mask. Despite this, his SaO₂ (as measured by pulse oximetry) increases only marginally and there is no improvement in his symptoms.

Examination

Examination findings in the chest are unchanged but he now appears exhausted and slightly confused.

Pulse	120 beats/min
Respiratory rate	16 breaths/min
Blood pressure	120/80 mmHg
SaO₂	83% (on 28% O₂)
Temperature	36°C

A repeat ABG is performed (6 hours after the first ABG).

Arterial blood gas		On 28% O₂
11/07/2005
Unit no.: 77655349
ID: Joseph Spielman
		Normal
H⁺	51.4 nmol/L	(35–45)
pH	7.29	(7.35–7.45)
PCO₂	6.9 kPa	(4.7–6.0)
PCO₂	52 mmHg	(35–45)
PO₂	6.4 kPa	(> 10.6)
PO₂	48 mmHg	(> 80)
Bicarb	24 mmol/L	(22–28)
BE	−0.9 mmol/L	(−2−+2)
SPO₂	84%	(> 98%)
Lactate	1.0	(0.4–1.5)
K	4.0 mmol/L	(3.5–5)
Na	137 mmol/L	(135–145)
Cl	99 mmol/L	(95–105)
iCa⁺	1.1 mmol/L	(1–1.25)
Hb	16.5 g/dL	(13–18)
Glucose	4.2 mmol/L	(3.5–5.5)

Questions

1. a) Describe his gas exchange.

b) Describe his acid–base status.

2. Should his oxygen now be stopped?

Case 7

History

A 77-year-old woman is admitted to the stroke ward with right-sided weakness, visual disturbance and slurred speech. She is commenced on nasogastric feeding due to swallowing problems but has a large vomit 24 hours later. She initially appears well but over the next few hours develops worsening breathing difficulties.

Examination

She is agitated, distressed and pyrexial. A dull percussion note and coarse crackles are evident at both lung bases. Other than acute confusion, neurological findings are unchanged from admission.

Pulse	92 beats/min
Respiratory rate	28 breaths/min
Blood pressure	112/65 mmHg
SaO₂ (60% O₂)	92%

Arterial blood gas		On 60% O₂
23/7/2006
Unit no.: 00654545
ID: Mary Waters
		Normal
H⁺	38.8 nmol/L	(35–45)
pH	7.41	(7.35–7.45)
PCO₂	4.43 kPa	(4.7–6.0)
PCO₂	33.2 mmHg	(35-45)
PO₂	8.67 kPa	(> 10.6)
PO₂	65.0 mmHg	(> 80)
Bicarb	21.2 mmol/L	(22–28)
BE	−2.8 mmol/L	(−2−+2)
SPO₂	92.7%	(> 98%)
Lactate	1.6	(0.4–1.5)
K	4.0 mmol/L	(3.5–5)
Na	144 mmol/L	(135–145)
Cl	103 mmol/L	(95–105)
iCa⁺	1.2 mmol/L	(1–1.25)
Hb	13 g/dL	(13–18)
Glucose	6.6 mmol/L	(3.5–5.5)

Questions

1. a) Describe her gas exchange.

b) Describe her acid–base status.

2. What is the most likely diagnosis?

3. Is her condition mild, moderate or severe?

Case 8

History

A 68-year-old man with chronic obstructive pulmonary disease is referred to hospital by his doctor with a short history of increased breathlessness and reduced effort tolerance. He is normally capable of walking around 500 metres but now has difficulty dressing and is breathless at rest.

Examination

He is lucid, alert and mildly distressed. He is using accessory muscles of respiration and breathing through pursed lips. Chest examination reveals features of hyperinflation, generally diminished breath sounds and scattered rhonchi (wheeze).

Pulse	96 beats/min
Respiratory rate	24 breaths/min
Blood pressure	138/82 mmHg
SaO₂ (room air)	78%

Arterial blood gas		On air
23/7/2006
Unit no.: 00654545
ID: Hamish Roy
		Normal
H⁺	43.2 nmol/L	(35–45)
pH	7.36	(7.35–7.45)
PCO₂	7.20 kPa	(4.7–6.0)
PCO₂	54.1 mmHg	(35–45)
PO₂	5.3 kPa	(> 10.6)
PO₂	40 mmHg	(> 80)
Bicarb	30.6 mmol/L	(22–28)
BE	+4.9 mmol/L	(−2−+2)
SPO₂	75.2%	(> 98%)
Lactate	1.2	(0.4–1.5)
K	3.7 mmol/L	(3.5–5)
Na	144 mmol/L	(135–145)
Cl	102 mmol/L	(95–105)
iCa⁺	1.2 mmol/L	(1–1.25)
Hb	16 g/dL	(13–18)
Glucose	4.9 mmol/L	(3.5–5.5)

Questions

1. a) Describe his gas exchange.

b) Describe his acid–base status.

2. Which one of the following ABG values is most likely to have changed significantly in the past 24 hours: pH, PCO₂, PO₂ or HCO₃?

3. Which two of the above ABG values indicate the need for caution when providing O₂ therapy?

Case 9

History

The patient from the previous case is treated with nebulised bronchodilators, oral prednisolone and 60% O₂ by face mask. His oxygen saturations improve significantly but when he is reviewed 1 hour later, his condition has deteriorated and he is unable to provide a history.

Examination

He is drowsy and barely rousable. He no longer appears to be in respiratory distress and his respiratory rate has fallen to 14 breaths/min. Chest examination is unchanged from previously.

Pulse	88 beats/min
Respiratory rate	14 breaths/min
Blood pressure	132/80 mmHg
SaO₂ (room air)	96%

Arterial blood gas		On 60% O₂
23/7/2006
Unit no.: 00654545
ID: Hamish Roy
		Normal
H⁺	50.8 nmol/L	(35–45)
pH	7.29	(7.35–7.45)
PCO₂	8.7 kPa	(4.7–6.0)
PCO₂	65.3 mmHg	(35–45)
PO₂	11.2 kPa	(> 10.6)
PO₂	84.0 mmHg	(> 80)
Bicarb	30.3 mmol/L	(24–30)
BE	+4.7 mmol/L	(−2−+2)
SPO₂	96.2%	(> 98%)
Lactate	1.2	(0.4–1.5)
K	3.6 mmol/L	(3.5–5)
Na	144 mmol/L	(135–145)
Cl	102 mmol/L	(95–105)
iCa⁺	1.2 mmol/L	(1–1.25)
Hb	16 g/dL	(13–18)
Glucose	5.0 mmol/L	(3.5–5.5)

Questions

1. a) Describe his gas exchange.

b) Describe his acid–base status.

2. What has been the cause of his deterioration?

Case 10

History

A 21-year-old woman presents to the emergency department with a 6-hour history of worsening breathlessness and wheeze. She has a past history of asthma with two previous exacerbations requiring hospital admission. She now feels very breathless and is obtaining no relief from her salbutamol inhaler.

Examination

She is tachypnoeic at 30 breaths/min, is using her accessory muscles of respiration and only just managing to speak in full sentences.

Auscultation of her chest reveals widespread polyphonic wheeze.

Pulse	115 beats/min
Blood pressure	120/80 mmHg
SpO₂	96% (room air)
Peak expiratory flow	160 L/s (predicted = 400 L/s)

Arterial blood gas		On air
12/11/2005
Unit no.: 12639943
ID: Jessica Goldman
		Normal
H⁺	42 nmol/L	(35–45)
pH	7.38	(7.35–7.45)
PCO₂	5.8 kPa	(4.7–6.0)
PCO₂	43 mmHg	(35–45)
PO₂	10.2 kPa	(> 10.6)
PO₂	76 mmHg	(> 80)
Bicarb	24 mmol/L	(22–28)
BE	−1.3 mmol/L	(−2_+2)
SaO₂	96%	(> 98%)
Lactate	1	(0.4 – 1.5)
K	4.0 mmol/L	(3.5–5)
Na	140 mmol/L	(135–145)
Cl	99 mmol/L	(95–105)
iCa⁺	1.12 mmol/L	(1–1.25)
Hb	13.0 g/dL	(11.5–15.5)
Glucose	5 mmol/L	(3.5–5.5)

Questions

1. a) Describe her gas exchange.

b) Describe her acid–base status.

2. Which of the above ABG values gives the greatest cause for concern?

3. How would you classify the severity of this asthma attack?

Case 11

History

A 23-year-old woman presents to the emergency department with a painful ankle, following a simple trip. While being examined by the emergency department doctor she becomes extremely agitated and upset. Despite a normal ankle X-ray and extensive reassurance by the emergency department staff, she refuses to believe that her ankle is not broken and starts crying. While leaving the department, she develops a clutching sensation in her chest, shortness of breath and a tingling sensation in her hands and around her mouth. She reports that she feels unable to take a deep breath.

Examination

The patient appears frightened and extremely distressed. Other than tachypnoea and a mild sinus tachycardia, cardiorespiratory examination is unremarkable. Electrocardiogram, chest X-ray and peak flow measurements are all normal.

Pulse	96 beats/min
Respiratory rate	36 breaths/min
Blood pressure	130/80 mmHg
SpO₂	100%

Arterial blood gas		On air
12/11/2006
Unit no.: 12534943
ID: Trinny Farqhuar
		Normal
H⁺	29 nmol/L	(35–45)
pH	7.53	(7.35–7.45)
PCO₂	3.14 kPa	(4.7–6.0)
PCO₂	24 mmHg	(35–45)
PO₂	14.3 kPa	(> 10.6)
PO₂	108 mmHg	(> 80)
Bicarb	24 mmol/L	(22–28)
BE	−1.8 mmol/L	(−2−+2)
SaO₂	99%	(> 98%)
Lactate	1	(0.4–1.5)
K	3.5 mmol/L	(3.5–5)
Na	140 mmol/L	(135–145)
Cl	99 mmol/L	(95–105)
iCa⁺	0.9 mmol/L	(1–1.25)
Hb	12.0 g/dL	(11.5–15.5)
Glucose	5 mmol/L	(3.5–5.5)

Questions

1. a) Describe her gas exchange.

b) Describe her acid–base status.

2. Are there any other abnormalities?

3. What is the likely diagnosis?

Case 12

History

A 40-year-old male is pulled from a house fire and brought to the emergency department in the early hours of the morning. The paramedics estimate he is likely to have been trapped in a smoke-filled room for up to 20 minutes prior to rescue.

Examination

The patient is heavily contaminated with soot and smells strongly of smoke. Fortunately he has not sustained any thermal injuries. He appears to be confused and has just vomited.

Baseline observations are normal, with an oxygen saturation of 99% on 15 L O₂ by mask.

Arterial blood gas		On 15 L O₂by mask
10/08/2005
Unit no.: 77634566
ID: Robert Jones
		Normal
H⁺	44 nmol/L	(35–45)
pH	7.36	(7.35–7.45)
PCO₂	4.5 kPa	(4.7–6.0)
PCO₂	34 mmHg	(35–45)
PO₂	47 kPa	(> 10.6)
PO₂	353 mmHg	(> 80)
Bicarb	18 mmol/L	(22–28)
BE	−5.5 mmol/L	(−2−+2)
SPO₂	100%	(> 98%)
Lactate	2	(0.4–1.5)
K	3.6 mmol/L	(3.5–5)
Na	145 mmol/L	(135–145)
Cl	103 mmol/L	(95–105)
iCa⁺	1.1 mmol/L	(1–1.25)
Hb	14 g/dL	(13–18)
Glucose	4 mmol/L	(3.5–5.5)
Carbon monoxide assay
CO	40%	(non-smokers < 3%)
		(smokers < 10%)

Questions

1. a) Describe his gas exchange.

b) Describe his acid–base status.

2. What is the most likely diagnosis?

3. Which of the values provided is falsely high: PaO₂, SaO₂ or Hb?

Case 13

History

A 79-year-old female has just been admitted to the general surgical ward to have a large bowel tumour surgically removed.

The tumour was discovered at colonoscopy after she presented to her doctor with a six month history of rectal bleeding.

On admission she appears to be severely short of breath and extremely tired. Further questioning reveals that her rectal blood loss has been no greater than usual.

Pulse	100 beats/min
Blood pressure	100/80 mmHg
Respiratory rate	24 breaths/min
SaO₂% (on air)	100%

Arterial blood gas		On air
06/06/2005
Unit no.: 943778
ID: Ethyl Swainson
		Normal
H⁺	32.3 nmol/L	(35–45)
pH	7.49	(7.35–7.45)
PCO₂	3.31 kPa	(4.7–6.0)
PCO₂	25 mmHg	(35–45)
PO₂	11.9 kPa	(> 10.6)
PO₂	89 mmHg	(> 80)
Bicarb	22 mmol/L	(22–28)
BE	−2 mmol/L	(−2−+2)
SPO₂	99.8%	(> 98%)
Lactate	1	(0.4–1.5)
K	3.8 mmol/L	(3.5–5)
Na	138 mmol/L	(135–145)
Cl	96 mmol/L	(95–105)
iCa⁺	1.17 mmol/L	(1–1.25)
Hb	6.8 g/dL	(13–18)
Glucose	3.9 mmol/L	(3.5–5.5)

Questions

1. a) Describe her gas exchange?

b) Describe her acid-base state?

2. What is the most likely cause of her breathlessness?

3. What would be the most effective way of improving O₂ delivery to her tissues?

Case 14

History

A 78-year-old woman is admitted to the emergency department with sudden-onset, generalised, severe, abdominal pain. She describes the pain as being colicky with no particular radiation. She does not complain of any alteration in her bowel habit, and has not vomited. Her only medical history is that of atrial fibrillation, for which she takes aspirin and digoxin.

Examination

On examination, the patient is haemodynamically stable with warm, well-perfused peripheries. Despite severe abdominal discomfort, abdominal examination is relatively unremarkable: the abdomen is soft in all four quadrants and is only tender on deep palpation. No hernias or aneurysms are palpable and rectal examination is unremarkable.

An abdominal and erect chest X-ray are taken and found to be normal.

During the course of the examination her clinical condition deteriorates and she is moved to the resuscitation area.

Arterial blood gas		On 10 L O₂by mask
10/08/2006
Unit no.: 7734211
ID: Susan Ulrik
		Normal
H⁺	52.5nmol/L	(35–45)
pH	7.28	(7.35–7.45)
PCO₂	4.39 kPa	(4.7–6.0)
PCO₂	33 mmHg	(35–45)
PO₂	28.6 kPa	(> 10.6)
PO₂	215 mmHg	(> 80)
Bicarb	16.2 mmol/L	(22–28)
BE	−10.4 mmol/L	(−2−+2)
SPO₂	99.8%	(> 98%)
Lactate	3.2	(0.4–1.5)
K	4.6 mmol/L	(3.5–5)
Na	135 mmol/L	(135–145)
Cl	96 mmol/L	(95–105)
iCa⁺	1.16 mmol/L	(1–1.25)
Hb	12 g/dL	(13–18)
Glucose	3.8 mmol/L	(3.5–5.5)

Questions

1. a) Describe her gas exchange.

b) Describe her acid–base status.

2. What is the most likely diagnosis?

Case 15

History

A 35-year-old woman with type 1 diabetes is brought to the emergency department by ambulance after being found in her house severely unwell. Following a discussion with her partner it emerges she has not been eating for the past few days due to a vomiting illness and, as a precaution, has also been omitting her insulin.

Examination

On examination, she appears drowsy and peripherally shut-down, with very dry mucous membranes. Her breath smells of acetone and her respirations are deep and sighing.

Pulse	130 beats/min
Blood pressure	100/60 mmHg
Respiratory rate	26 breaths/min
BM (blood glucose)	> 25 mmoL/L

Physical examination of her chest and abdomen is unremarkable.

Arterial blood gas		On 10 L O₂by mask
27/02/2005
Unit no.: 77735566
ID: Isla Tanner
		Normal
H⁺	88.9 nmol/L	(35–45)
pH	7.05	(7.35–7.45)
PCO₂	1.5 kPa	(4.7–6.0)
PCO₂	11 mmHg	(35–45)
PO₂	28.4 kPa	(> 10.6)
PO₂	187 mmHg	(> 80)
Bicarb	6.0 mmol/L	(24–30)
BE	−25.2 mmol/L	(−2−+2)
SPO₂	99.8%	(> 98%)
Lactate	1	(0.4–1.5)
K	4.6 mmol/L	(3.5–5)
Na	141 mmol/L	(135–145)
Cl	96 mmol/L	(95–105)
iCa⁺	1.25 mmol/L	(1–1.25)
Hb	12 g/dL	(13–18)
Glucose	35 mmol/L	(3.5–5.5)

Questions

1. a) Describe her gas exchange.

b) Describe her acid–base status.

2. Calculate the anion gap.

3. What is the most likely diagnosis?

Case 16

History

A 37-year-old well-known local vagrant is brought into the department unconscious. He was found near a bottle of vodka and a half-empty bottle of what appears to be methanol. It is unclear if he has drunk any of the contents.

Examination

The patient is unkempt with a significantly reduced conscious level (Glasgow coma scale score = 9). There are no apparent focal neurological abnormalities.

Arterial blood gas		On air
10/07/2006
Unit no.: 35477899
ID: Gary Souness
		Normal
H⁺	63.3 nmol/L	(35–45)
pH	7.20	(7.35–7.45)
PCO₂	3.3 kPa	(4.7–6.0)
PCO₂	25 mmHg	(35–45)
PO₂	12.8 kPa	(> 10.6)
PO₂	96 mmHg	(> 80)
Bicarb	9.5 mmol/L	(22–28)
BE	−16.2 mmol/L	(−2−+2)
SPO₂	97.8%	(> 98%)
Lactate	1.3	(0.4–1.5)
K	4.5 mmol/L	(3.5–5)
Na	136 mmol/L	(135–145)
Cl	99 mmol/L	(95–105)
iCa⁺	1.1 mmol/L	(1–1.25)
Hb	13.5 g/dL	(13–18)
Glucose	3.8 mmol/L	(3.5–5.5)

Questions

1. a) Describe his gas exchange.

b) Describe his acid–base status.

2. What is the anion gap?

3. Is the acid–base status consistent with methanol ingestion?

Case 17

History

A 52-year-old man is being investigated on the urology ward for recurrent renal stones. He also complains of mild fatigue and lethargy. There is no history of gastrointestinal disturbance and he is not on any regular medications.

Examination

The patient is well and clinical examination reveals no abnormalities.

As part of the investigations an ABG is obtained.

Arterial blood gas		On air
23/04/2006
Unit no.: 27634943
ID: Roger Parry
		Normal
H⁺	43 nmol/L	(35–45)
pH	7.37	(7.35–7.45)
PCO₂	4.2 kPa	(4.7–6.0)
PCO₂	31.5 mmHg	(35–45)
PO₂	13.2 kPa	(> 10.6)
PO₂	99.0 mmHg	(>80)
Bicarb	18 mmol/L	(22–28)
BE	−7 mmol/L	(−2−+2)
SPO₂	99%	(> 98%)
Lactate	1	(0.4–1.5)
K	3.0 mmol/L	(3.5–5)
Na	137 mmol/L	(135–145)
Cl	109 mmol/L	(95–105)
iCa⁺	1.0 mmol/L	(1–1.25)
Hb	13.0 g/dL	(11.5–15.5)
Glucose	4 mmol/L	(3.5–5.5)

Questions

1. a) Describe his gas exchange.

b) Describe his acid–base status.

2. Calculate the anion gap.

3. What is the likeliest diagnosis?

Case 18

History

An 18-year-old is admitted to the toxicology unit having taken a large overdose of an unknown substance 5 hours earlier. She complains of nausea and a high-pitched noise in her ears.

Examination

On examination, she is mildly confused. Her respirations are increased in both rate and depth. Examination is otherwise unremarkable.

Pulse	100 beats/min
Respiratory rate	26 breaths/min
Blood pressure	132/100 mmHg
Temperature	37.6°C
O₂%	99%

Arterial blood gas		On air
10/09/2006
Unit no.: 27634943
ID: Libby Farqhuar
		Normal
H⁺	38.8 nmol/L	(35–45)
pH	7.41	(7.35–7.45)
PCO₂	3.01 kPa	(4.7–6.0)
PCO₂	22.6 mmHg	(35–45)
PO₂	14.1 kPa	(> 10.6)
PO₂	97.5 mmHg	(> 80)
Bicarb	17.6 mmol/L	(22–28)
BE	−8.3 mmol/L	(−2−+2)
SPO₂	99%	(> 98%)
Lactate	1.4	(0.4–1.5)
K	3.6 mmol/L	(3.5–5)
Na	140 mmol/L	(135–145)
Cl	99 mmol/L	(95–105)
iCa⁺	1.2 mmol/L	(1–1.25)
Hb	13.0 g/dL	(11.5–15.5)
Glucose	5 mmol/L	(3.5–5.5)

Questions

1. a) Describe her gas exchange.

b) Describe her acid–base status.

2. Calculate the anion gap.

3. What substance is she most likely to have taken?

Case 19

History

A 24 year old man is brought to hospital by his family after becoming unwell at home. They report that he has no history of significant medical illness but has recently been undergoing tests for progressive fatigue and weight loss. Over the last few days he has become increasingly weak and lethargic and has also complained of muscle cramps. They became alarmed today when he appeared drowsy and disoriented.

Examination

The patient appears listless and confused. He has cool peripheries and poor capillary refill. He is afebrile and there is no rash, lymphadenopathy or meningism. Abdominal examination is unremarkable and there are no focal chest or neurological signs.

Pulse	120 beats/min
Respiratory rate	25 breaths/min
Blood pressure	75/55 mmHg
Temperature	36.5°C
BM	2.9

Arterial blood gas		On air
10/08/2005
Unit no.: 456986793
ID: Rufus Wainwright
		Normal
H⁺	48 nmol/L	(35–45)
pH	7.32	(7.35–7.45)
PCO₂	3.3 kPa	(4.7–6.0)
PCO₂	24.8 mmHg	(35–45)
PO₂	13 kPa	(> 10.6)
PO₂	97 mmHg	(> 80)
Bicarb	13.4 mmol/L	(22–28)
BE	−13.9 mmol/L	(−2−+2)
SO₂	99%	(> 98%)
Lactate	3	(0.4–1.5)
K	5.6 mmol/L	(3.5–5)
Na	125 mmol/L	(135–145)
Cl	101 mmol/L	(95–105)
iCa⁺	1.2 mmol/L	(1–1.25)
Hb	13.0 g/dL	(13–18)
Glucose	2.5 mmol/L	(3.5–5.5)

Questions

1. a) Describe his gas exchange.

b) Describe his acid–base state?

2. Are there any other abnormalities on the ABG?

3. What specific treatment does this patient require?

Case 20

History

An 87-year-old man has been found collapsed in the ward toilet. Cardiopulmonary resuscitation was commenced promptly, as no pulse or respiratory effort was detected, and has now been in progress for 12 minutes. He has a past medical history of ischaemic heart disease, dementia and chronic renal failure.

Examination

The patient has a Glasgow coma scale score of 3 and appears pale and mottled. The cardiac monitor reveals an agonal rhythm as shown below. No pulses are palpable and there is no respiratory effort. He is currently being ventilated by a bag and mask on 15 L/min of O₂.

Arterial blood gas		On 15 L O₂by bag mask
10/02/2004
Unit no.: 42333993
ID: David King
		Normal
H⁺	160 nmol/L	(35–45)
pH	6.8	(7.35–7.45)
PCO₂	4.8 kPa	(4.7–6.0)
PCO₂	36 mmHg	(35–45)
PO₂	32 kPa	(> 10.6)
PO₂	240 mmHg	(> 80)
Bicarb	3.8 mmol/L	(22–28)
BE	−20 mmol/L	(−2−+2)
SO₂	100%	(> 98%)
Lactate	9	(0.4–1.5)
K	4.5 mmol/L	(3.5–5)
Na	136 mmol/L	(135–145)
Cl	96 mmol/L	(95–105)
Ca⁺	1.1 mmol/L	(1–1.25)
Hb	14.0 g/dL	(13.5–18.5)
Glucose	4 mmol/L	(3.5–5.5)

Questions

1. a) Describe his gas exchange.

b) Describe his acid–base status.

2. What is his prognosis?

Case 21

History

A 59-year-old male with a history of alcohol excess presents to the emergency department with a 3-day history of severe upper abdominal pain. He now also feels very breathless. He admits to drinking up to 100 units of alcohol per week for the past few weeks.

Examination

The patient is in evident distress and appears very unwell. He is tachycardic (120 beats/min) and hypotensive (75/60 mmHg). There is marked epigastric tenderness.

A venous blood test taken on admission reveals a grossly elevated amylase (1890 U/ml) and C-reactive protein (274 mg/L). A chest X-ray on admission is shown in Figure 34.

Arterial blood gas		On 15 L O₂by mask with reservoir bag
10/08/2005
Unit no.: 45679393
ID: Daniel Carter
		Normal
H⁺	47 nmol/L	(35–45)
pH	7.33	(7.35–7.45)
PCO₂	3.24 kPa	(4.7–6.0)
PCO₂	24.3 mmHg	(35–45)
PO₂	10.8 kPa	(> 10.6)
PO₂	81 mmHg	(> 80)
Bicarb	14.9 mmol/L	(22–28)
BE	−11.8 mmol/L	(−2−+2)
SPO₂	99%	(> 98%)
Lactate	3.1	(0.4–1.5)
K	3.6 mmol/L	(3.5–5)
Na	141 mmol/L	(135–145)
Cl	96 mmol/L	(95–105)
iCa⁺	0.89 mmol/L	(1–1.25)
Hb	12.0 g/dL	(13.5–18.5)
Glucose	16 mmol/L	(3.5–5.5)

Questions

1. a) Describe his gas exchange.

b) Describe his acid–base status.

2. What is his approximate FiO₂?

3. What is the most likely diagnosis?

Case 22

History

A 35-year-old woman on a gynaecology ward develops a severe vomiting illness one day after elective sterilisation. She continues to vomit profusely for a further 3 days. Examination of her fluid balance chart reveals that she is failing to keep up with her fluid losses but has not been prescribed intravenous fluids.

Examination

The patient appears dehydrated with reduced skin turgor and dry mucous membranes.

Abdominal examination is unremarkable.

Pulse	100 beats/min
Respiratory rate	10 breaths/min
Blood pressure	160/100 mmHg
Temperature	36.6°C
O₂%	96%

Arterial blood gas		On air
23/08/2006
Unit no.: 27634943
ID: Jenny Alegranza
		Normal
H⁺	36 nmol/L	(35–45)
pH	7.44	(7.35–7.45)
PCO₂	6.4 kPa	(4.7–6.0)
PCO₂	48 mmHg	(35–45)
PO₂	11.1 kPa	(> 10.6)
PO₂	83 mmHg	(> 80)
Bicarb	32 mmol/L	(22–28)
BE	+4 mmol/L	(−2−+2)
SPO₂	96%	(> 98%)
Lactate	1	(0.4–1.5)
K	3.0 mmol/L	(3.5–5)
Na	133 mmol/L	(135–145)
Cl	91 mmol/L	(95–105)
iCa⁺	1.0 mmol/L	(1–1.25)
Hb	11.0 g/dL	(11.5–15.5)
Glucose	5 mmol/L	(3.5–5.5)

Questions

1. a) Describe her gas exchange.

b) Describe her acid–base status.

2. What electrolyte abnormalities are present?

3. What treatment will correct the acid–base abnormality?

Case 23

History

An 8-week-old child is brought to the emergency department, with weight loss and projectile vomiting. The parents report that he had an uncomplicated delivery with no postpartum complications. He initially fed well, appeared to be thriving and gave no cause for concern but has deteriorated markedly over the past 2 weeks, vomiting all of his meals and now losing weight.

Examination

The child is agitated, crying and is malnourished. His mucous membranes are dry and on examination of his abdomen a small mass is found in the epigastrium.

Capillary blood gas		On air
05/10/2005
Unit no.: 28734943
ID: Richard Barter
		Normal
H⁺	29 nmol/L	(35–45)
pH	7.54	(7.35–7.45)
PCO₂	6.1 kPa	(4.7–6.0)
PCO₂	45.8 mmHg	(35–45)
PO₂	11.2 kPa	(> 10.6)
PO₂	80 mmHg	(> 80)
Bicarb	37.5 mmol/L	(22–28)
BE	+14 mmol/L	(−2–+2)
SaO₂	99%	(> 98%)
Lactate	1	(0.4–1.5)
K	2.5 mmol/L	(3.5–5)
Na	135 mmol/L	(135–145)
Cl	86 mmol/L	(95–105)
iCa⁺	1 mmol/L	(1–1.25)
Hb	18.0 g/dL	(13.5–18.5)

Questions

1. a) Describe his gas exchange.

b) Describe his acid–base status.

2. Considering the pH and HCO3: is the PaCO₂ higher or lower than you would expect?

3. What is the underlying diagnosis?

Case 24

History

A 36-year-old pregnant woman on the maternity ward complains of feeling short of breath. She has no other symptoms and no relevant past medical history.

Examination

On examination, the patient is heavily pregnant but appears otherwise well. Examination of her chest reveals no abnormalities.

Pulse	110 beats/min
Respiratory rate	20 breaths/min
Blood pressure	112/100 mmHg
Temperature	36.6°C
O₂%	99%

An ABG is performed.

Arterial blood gas		On air
18/08/2005
Unit no.: 27634943
ID: Julie Donaldson
		Normal
H⁺	35 nmol/L	(35–45)
pH	7.45	(7.35–7.45)
PCO₂	4.9 kPa	(4.7–6.0)
PCO₂	35 mmHg	(35–45)
PO₂	4.7 kPa	(> 10.6)
PO₂	35 mmHg	(35–45)
Bicarb	24.0 mmol/L	(24–30)
BE	2 mmol/L	(−2−+2)
SPO₂	74%	(> 98%)
Lactate	1	(0.4–1.5)
K	3.6 mmol/L	(3.5–5)
Na	138 mmol/L	(135–145)
Cl	104 mmol/L	(95–105)
iCa⁺	1.14 mmol/L	(1–1.25)
Hb	13.0 g/dL	(11.5–15.5)
Glucose	5 mmol/L	(3.5–5.5)

Questions

1. a) Describe her gas exchange.

b) Describe her acid–base status.

2. What is the most likely explanation for the low PaO₂?

Case 25

History

A 55-year-old woman on the orthopaedic ward complains of sudden-onset breathlessness and pain on the left-hand side of her chest. She underwent elective knee replacement surgery 4 days previously and has been immobile in bed since the operation. She is otherwise well with no relevant past medical history.

Examination

The patient appears well but slightly short of breath. Other than mild tachycardia and tachypnoea, examination of the cardiovascular and respiratory systems yields no positive findings and there is no clinical evidence of deep-vein thrombosis.

A chest X-ray reveals no abnormalities and an electrocardiogram shows only sinus tachycardia.

Pulse	98 beats/min
Respiratory rate	20 breaths/min
Blood pressure	160/100 mmHg
Temperature	36.6°C
O₂%	99%

Arterial blood gas		On air
10/08/2006
Unit no.: 27634943
ID: Jill Archerson
		Normal
H⁺	36 nmol/L (35–45)
pH	7.43	(7.35–7.45)
PCO₂	4.9 kPa	(4.7–6.0)
PCO₂	37 mmHg	(35–45)
PO₂	12.1 kPa	(> 10.6)
PO₂	91 mmHg	(> 80)
Bicarb	25.8 mmol/L	(22–28)
BE	−1.8 mmol/L	(−2−+2)
SPO₂	99%	(> 98%)
Lactate	1	(0.4–1.5)
K	3.8 mmol/L	(3.5–5)
Na	136 mmol/L	(135–145)
Cl	99 mmol/L	(95–105)
iCa⁺	1.2 mmol/L	(1–1.25)
Hb	10.0 g/dL	(11.5–15.5)
Glucose	5 mmol/L	(3.5–5.5)

Questions

1. a) Describe her gas exchange.

b) Describe her acid–base status.

2. What is the A–a gradient?

3. Does she require any further investigation?

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