Respiratory medicine

Mark A Rodrigues and Emily R McCall-Smith

Outline

Station 3.1: Acute exacerbation of asthma

Station 3.3: Community-acquired pneumonia (CAP)

Station 3.4: Hospital-acquired pneumonia

Station 3.1: Acute exacerbation of asthma

You are the junior doctor working in the emergency department. You are asked urgently to review Mr Cannon, a 23-year-old asthmatic, who has presented with breathlessness and wheeze.

Patient Details

Name:	Russell Cannon
DOB:	21/03/91
Hospital Number:	2103914532
Weight:	65 kg
Height:	1.6 m
Consultant:	Dr Roy
Hospital/Ward:	WGH Ward 4
Current Medications:	Salbutamol (100 micrograms/metered dose) 2 puffs INH PRN
Allergies:	None known
Admission date:	22/10/14

Initial differential diagnosis of acute dyspnoea

Respiratory: Asthma, pneumothorax, PE, pneumonia

Cardiac: MI, pulmonary oedema, cardiac tamponade, valvular pathology, e.g. aortic stenosis

Complications of an acute exacerbation of asthma

Pneumothorax

Respiratory failure/arrest

Hypokalaemia (from salbutamol treatment)

Right heart failure (chronic asthma)

Asthma initial management summary

Resuscitate using an ABCDE approach

Initial Assessment

Airway

Assess patency of the airway. Can you hear any added airway noises?

‘The patient is maintaining their airway and no stridor is audible.’

No additional airway support is required at present, but remember the patient could deteriorate quickly.

Breathing

Check respiratory rate and oxygen saturations

Look at the work of breathing: nasal flaring, use of accessory muscles. Is the patient able to complete sentences? Often patients with respiratory distress fix their rib cage and shoulder girdle by supporting themselves on straight arms and grasping the sides of the bed

Perform a respiratory exam, particularly assessing for chest wall movement, air entry into the lungs, and additional sounds (crackles or wheeze) on auscultation. Also look for signs of a pneumothorax by assessing the percussion note. Tracheal deviation, displacement of the apex beat away from the side of the pneumothorax and haemodynamic instability are clinical findings indicating a pneumothorax is under tension. This is a medical emergency, requiring urgent needle decompression

‘RR 35/min, oxygen saturations are 89% on room air. The patient is using his accessory muscles and unable to speak in full sentences. On auscultation, there is symmetrical chest wall movement, lung fields are resonant throughout, with reduced air entry at the base of the lungs, and a widespread bilateral polyphonic wheeze.’

You start the patient on high-flow oxygen via a non-rebreather mask (to maintain saturations between 94% and 98%). You prescribe 5 mg of salbutamol to be nebulized with oxygen.

Prescribe (see Figs 3.1 and 3.2)

Bronchodilator, e.g. SALBUTAMOL 5 mg NEB (driven with oxygen) STAT

High-flow OXYGEN, e.g. OXYGEN 15 L/min via NON-REBREATHER MASK

Figure 3.1

Figure 3.2

Circulation

Assess haemodynamic status by measuring pulse, blood pressure, and capillary refill time. A tachycardia indicates worsening asthma, whereas a bradycardia can be a pre-terminal event

Perform a cardiovascular exam, as breathlessness may be due to a cardiovascular cause such as aortic stenosis or left heart failure

Obtain IV access and take bloods

Consider commencing IV fluids, particularly if there is evidence of shock

‘The patient’s heart rate is 134 bpm, with a BP of 145/95 mmHg and CRT of 2 seconds. There is no evidence of heart failure or valvular disease on cardiovascular exam.’

No cardiovascular support is required at present.

Disability

Assess the patient’s GCS or AVPU level–are they becoming exhausted? Check the blood sugar

‘The patient is GCS 15 (E4, M6, V5). His blood sugar is 4.8 mmol/L.’

When describing a GCS score to a senior, always divide it into the separate categories (e.g. E3, M4, V4)–this allows them to get a more accurate picture.

Exposure

Examine the abdomen, check the temperature, and remember to check the legs for any sign of a DVT

‘The patient’s abdomen is soft and non-tender, and there is no evidence of DVT. He is apyrexial.’

Initial Investigations

Ask one of your colleagues, if available, to perform the ABG or request the CXR while you continue your assessment (see Table 3.1).

Table 3.1

Assessment of severity of asthma

Moderate	Acute severe	Life threatening
Increasing symptoms	Any one of:	Acute severe asthma+any one of:
Peak expiratory flow 50–75% of best or predicted	Peak expiratory flow 33–50% of best or predicted	Peak expiratory flow<33% of best or predicted
No features of acute severe asthma	Respiratory rate≥25/min	Oxygen saturations<92%
	Heart rate≥110/min	PaO₂<8 kPa
	Unable to complete sentences in one breath	Normal PaCO₂ (4.6–6 kPa)
	Unable to perform peak flow	Silent chest
		Cyanosis
		Poor respiratory effort
		Arrhythmia
		Exhaustion, altered conscious level

ABG: Perform if (a) the SpO₂ is<92% or (b) if there are any features of life-threatening asthma. Patients are likely to be hypoxic. The PaCO₂ is likely to be low (due to hyperventilation), causing a respiratory alkalosis (low H⁺/high pH). However, if a patient becomes exhausted, their respiratory rate will reduce, and the PaCO₂ will go from low to normal to high (indicating a near-fatal exacerbation)

Bloods: Check Hb (for anaemia), U&Es (for dehydration and to monitor potassium when giving salbutamol), WCC, CRP±blood cultures (for evidence of infection). Theophylline levels if on aminophylline

Peak flow: This helps measure the severity of an asthma attack (Table 3.1), as well as the response to treatment. It is most useful if measured as a percentage of a patient’s previous best, but it can also be measured as a percentage of predicted (which is based on height, sex and age)

ECG: Arrhythmias can be a sign of a life-threatening attack (or if not a clear asthma history, could be an alternative diagnosis)

CXR is indicated if:

there are any life-threatening features of asthma

there is another diagnosis suspected, e.g. pneumothorax

bacterial infection is suspected

failure to respond to treatment

prior to CPAP/BiPAP/intubation

‘The patient’s peak flow is 40% of his usual best. ABG on air shows hypoxaemia and a respiratory alkalosis (PaO₂7 kPa, PaCO₂3.1 kPA, H⁺28 nmol/L (pH 7.55), and HCO₃20.3 mmol/L). CXR shows hyperinflation. The lungs are clear, no pneumothorax. ECG shows sinus tachycardia. Bloods are normal.’

Table 3.2

Mr Cannon’s blood and ABG results

Initial Management [1]

Oxygen: Should be given to all hypoxic patients. Aim for saturations of 94–98%

Salbutamol: 5 mg nebulized with oxygen should be given as soon as possible. These can then be given ‘back-to-back’, i.e. every 10 minutes if the initial response is poor. Only consider IV beta-2 agonists for those who are unable to undergo inhaled therapy

Ipratropium bromide: 500 micrograms every 4–6 hours, nebulized, if the attack is severe or life-threatening or if there is a poor response to nebulized salbutamol

Corticosteroids: 40 mg prednisolone (oral) or 200 mg hydrocortisone (IV) if unable to swallow. Corticosteroids should be given in all cases of acute asthma. Oral corticosteroids are as effective as IV corticosteroids if the patient can absorb them. Continue for at least 5 days or until recovery

Antibiotics: Only required if there is any evidence of an infection (pyrexia, crackles on auscultation/consolidation on CXR, or raised WCC/CRP)

Review medications: May need to stop drugs such as beta-blockers and sedatives.

Prescribe (see Figs 3.1 and 3.2)

Corticosteroids, e.g. PREDNISOLONE 40 mg oral STAT

Bronchodilators, e.g. IPRATROPIUM BROMIDE 500 micrograms NEB (driven with oxygen) STAT and SALBUTAMOL 5 mg NEB (driven with oxygen) STAT

Remember to involve you senior early. They may consider giving a single dose of IV magnesium sulfate in a life-threatening or near-fatal attack, or in patients who have not made a good response to nebulized salbutamol.

Involve HDU/ITU early on. Severe asthmatics may end up needing intubation

IV aminophylline is occasionally given by senior doctors. This may be considered in patients who have a severe or life-threatening attack, and have responded poorly to initial treatment. Theophylline levels should be checked if the patient is already on theophylline or aminophylline, as it has a narrow therapeutic index.

Reassessment

Repeat the ABCDE process

Peak flow should be repeated at 15 and 30 minutes

ABGs should be repeated within 30 minutes if there is a poor response to treatment

Titrate oxygen to the saturations and ABG results

‘The patient is starting to improve. Airway is patent and RR is now 20/min. Oxygen saturations are now 95% on 2 L of nasal cannula oxygen. There is still expiratory wheeze; however, air entry has improved. HR is 118 bpm and BP is 120/80 mmHg. Peak flow is now 60% of predicted. Repeat ABG on 2 L oxygen shows PaO₂15 kPa, PaCO₂3.8 kPA, H⁺30 nmol/L (pH 7.52), and HCO₃23.1 mmol/L.’

Table 3.3

Mr Cannon’s repeat ABG

Parameter	Value	Normal range (units)
pH	7.52	7.35–7.45
H⁺	30 nmol/L	35–45 (nmol/L)
PaO₂	15 kPa on 2 L of nasal cannula oxygen	>10 (kPa) on air
PaCO₂	3.8 kPa	4.7–6.0 (kPa)
HCO₃	23.1 mmol/L	22–26 (mmol/L)

Side effects of salbutamol include tremor, tachycardia and hypokalaemia. Keep an eye on the U&Es and replace potassium with slow IV fluids if required.

Definitive Management

Ideally patients should be admitted under a respiratory specialist rather than to a general ward

Aim to identify the trigger that precipitated the asthma attack

Continue regular nebulized therapy initially, e.g. salbutamol 5 mg every 4 hours±ipratropium bromide 500 micrograms every 6 hours

After 24 hours, consider changing nebulized salbutamol to inhaled salbutamol, and adding in high-dose inhaled corticosteroid

Continue 40 mg of prednisolone for at least 5 days. The dose does not need to be tapered down, unless the patient is on maintenance corticosteroid treatment or has been on corticosteroid treatment for>3 weeks

Prescribe ongoing oxygen requirement, e.g. 2 L/min via nasal cannulae

Don’t forget to prescribe DVT prophylaxis as long as there are no contraindications

Patients can be discharged when they are no longer requiring nebulized therapy, and when the beta-2-agonist therapy can be stretched to every 4 hours

Prior to discharge the PEFR should be>75% of best/predicted, with<25% diurnal variation

Patients should be discharged with a personal self-management asthma plan and their inhaler technique should be assessed

After discharge, patients should be reviewed by an asthma-specialist within 30 days.

Prescribe (see Figs 3.1 and 3.2)

Bronchodilators, e.g. SALBUTAMOL 5 mg NEB (driven with oxygen or air) 2 HOURLY

IPRATROPIUM BROMIDE 500 micrograms NEB (driven with oxygen or air) 6 HOURLY

Corticosteroids, e.g. PREDNISOLONE 40 mg OD ORAL for 5 DAYS

Thrombopophalaxis, e.g. FONDAPARINUX 2.5 mg SC OD

OXYGEN, e.g. OXYGEN 2 L/min via NASAL CANNULAE

STOP

High-flow oxygen

Handing over the Patient

‘Mr Cannon is a 23-year-old gentleman who presented this evening with a life-threatening exacerbation of asthma.

He was acutely breathless, with a RR 35/min, saturations of 89% on air, widespread wheeze in the lung field, and poor basal lung entry. He has been treated with oxygen, 2×5 mg salbutamol nebulizers back to back, ipratropium bromide, and prednisolone, and is responding well.

Current observations are RR 20/min, SpO₂ 95% on 2 L of O₂. HR is 118/min and BP is 120/80 mmHg. Peak flow is 60% of predicted, and ABG shows a respiratory alkalosis. He has been reviewed by the HDU registrar who is happy with ward level management at present.

He is being transferred to the ward on 2-hourly salbutamol nebulizers and 6- hourly ipratropium. CXR shows hyperexpanded lungs, and bloods are normal. Please could you review him in one hour and check his peak flow again within 30 minutes.’

Features of a near fatal attack of asthma

Raised PaCO₂

Patient requiring mechanical ventilation

Bradycardia

Station 3.2: Exacerbation of COPD

You are the junior doctor working in the medical assessment unit. Your next patient is Mrs Johnson, an acutely breathless 67-year-old lady with a history of COPD. She normally controls this with inhalers alone, and has no home nebulizers or long-term oxygen therapy. She says she is more breathless and wheezy but her sputum has not changed in colour.

Patient Details

Name:	Mary Johnson
DOB:	13/09/47
Hospital Number:	1309476374
Weight:	78 kg
Height:	1.55 m
Consultant:	Dr Jones
Hospital/Ward:	WGH Ward 4
Current Medications:	Salbutamol (100 micrograms/metered dose) 2 puffs INH PRN
Allergies:	None known
Admission date:	19/10/14

Initial differential diagnosis of acute breathlessness and wheeze

Respiratory: Exacerbation of COPD, exacerbation of asthma, acute viral or bacterial bronchitis

Cardiac: Acute left ventricular failure

Other: Anaphylaxis, inhaled foreign body

Long-term complications of COPD

Non-infective exacerbation of COPD

Infective exacerbation of COPD

Initial Assessment

Airway

Assess patency of the airway

‘The airway is patent.’

No additional airway support is currently required.

Breathing

Assess respiratory rate, oxygen saturations, work of breathing and evidence of tiring. Percuss carefully, particularly to exclude pneumothoraces (increased risk in COPD, especially bullous emphysema). Auscultate for air entry, wheeze and crepitations

‘RR 30/min, oxygen saturations are 82% on 2 L oxygen, with increased work of breathing. Resonant lung fields. There is good bilateral air entry with widespread inspiratory wheeze. No crepitations.’

You give oxygen via a Venturi mask and nebulized salbutamol and ipratropium. You also perform an arterial blood gas.

COPD Exacerbation Management [2]

Resuscitate using an approach

Oxygen & ABGs

Bronchodilators

Corticosteroids

Antibiotics and fluids (if indicated)

Prescribe (see Figs 3.3 and 3.4)

Bronchodilators, e.g. SALBUTAMOL 5 mg NEB (driven with oxygen) STAT and IPRATROPIUM BROMIDE 500 micrograms NEB (driven with oxygen) STAT

Controlled OXYGEN, e.g. 60% via VENTURI MASK

Figure 3.3

Figure 3.4

Circulation

Assess haemodynamic stability by measuring pulse, blood pressure, capillary refill time (centrally and peripherally)

Perform a cardiovascular exam, looking at the JVP and listening to the lung bases for evidence of heart failure, and assessing the heart sounds for evidence of valvular disease, all of which can cause dyspnoea

‘HR 84 bpm, BP 122/74 mmHg. Mrs Johnson has warm peripheries with a CRT<2 seconds. She has good volume peripheral pulses. CV exam reveals normal HS, no murmurs, and no evidence of heart failure.’

Secure IV access and take bloods.

Disability

Assess her conscious level, using AVPU (is the patient Alert? If not, do they respond to Verbal or Painful stimuli? Or are they Unresponsive?) or GCS. Check glucose levels.

‘She is alert but finding it difficult to speak in sentences. Her blood sugar is 9.5 mmol/L.’

Exposure

Check the patient’s temperature. Expose the patient. Look for sources of infection, evidence of anaphylaxis (urticaria, erythema and oedema), and of a DVT

‘Mrs Johnson’s temperature is 36.9°C. The rest of the examination is normal.’

Initial Investigations

In contrast to asthma, peak flow is not useful in the management of acute COPD.

ABG: One of the most important investigations in an exacerbation of COPD. It allows assessment of the degree of oxygenation (PaO₂) and ventilation (PaCO₂). Check within 20 minutes of starting or changing flow of oxygen. Aim for a PaO₂>6.6 kPa and H⁺<55 (pH>7.25). If this is achieved, increase the oxygen to achieve PaO₂>7.5 kPa. Aim for oxygen saturations of 88–92%. If possible, compare to a baseline, e.g. clinic ABG result

CXR: To exclude other causes of dyspnoea, especially a pneumothorax. Look for areas of consolidation. This is a priority investigation and may need to be a portable CXR if the patient is not stable enough to go to the X-ray department

ECG: Look for evidence of a myocardial infarction or arrhythmias

Bloods: FBC, U&Es, CRP. Look for evidence of infection, check for anaemia, assess renal function. Theophylline levels if on aminophylline

Blood culture: If the patient is pyrexial

Sputum culture: If the patient has purulent sputum

‘ABG (on 2 L/min oxygen) PaO₂6.0 kPa, PaCO₂3.1 kPa, H⁺33 nmol/L (pH 7.48), HCO₃⁻26 mmol/L. WCC 8.6×10⁹/L. CRP is 12 mg/L. Renal function is normal. CXR shows hyperinflated lungs with coarsening of the background markings in keeping with COPD. No consolidation or pneumothorax. ECG: sinus rhythm.’

Table 3.4

Mrs Johnson’s blood test and ABG results

Parameter	Value	Normal range (units)
WCC	8.6×10⁹/L	4–11 (×10⁹/L)
Neutrophil	6×10⁹/L	2–7.5 (×10⁹/L)
Lymphocyte	3×10⁹/L	1.4–4 (×10⁹/L)
Platelet	220×10⁹/L	150–400 (×10⁹/L)
Haemoglobin	150 g/L	Men: 135–177 (g/L) Women: 115–155 (g/L)
CRP	12 mg/L	0–5 (mg/L)
Urea	4.5 mmol/L	2.5–6.7 (mmol/L)
Creatinine	112 μmol/L	79–118 (μmol/L)
eGFR	>60 mL/min	>60 (mL/min)
Sodium	140 mmol/L	135–146 (mmol/L)
Potassium	4.5 mmol/L	3.5–5.0 (mmol/L)
pH	7.48	7.35–7.45
PaO₂	6 kPa on air	>10 (kPa) on air
PaCO₂	3.1 kPa	4.7–6.0 (kPa)
HCO₃	26 mmol/L	22–26 (mmol/L)
H⁺	33 nmol/L	35–45 (nmol/L)

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Nov 18, 2017 | Posted by admin in PHARMACY | Comments Off

Airway

Breathing

Circulation

Disability

Exposure

Initial Management [1]

Airway

Breathing

Circulation

Disability

Exposure

Basicmedical Key

Fastest Basicmedical Insight Engine

Respiratory medicine

Respiratory medicine

Station 3.1: Acute exacerbation of asthma

Initial Assessment

Initial Investigations

Reassessment

Definitive Management

Handing over the Patient

Station 3.2: Exacerbation of COPD

Initial Assessment

Initial Investigations

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Basicmedical Key

Fastest Basicmedical Insight Engine

Respiratory medicine

Respiratory medicine

Station 3.1: Acute exacerbation of asthma

Initial Assessment

Airway

Breathing

Circulation

Disability

Exposure

Initial Investigations

Initial Management [1]

Reassessment

Definitive Management

Handing over the Patient

Station 3.2: Exacerbation of COPD

Initial Assessment

Airway

Breathing

Circulation

Disability

Exposure

Initial Investigations

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