Respiratory Failure

Dr Svitlana ZheleznaClinical Teaching Fellow

UHCW NHS Trustsvitlana.zhelezna@uhcw.nhs.uk

2013/2014 academic year

Learning objectives:

Describe the clinical features, potential causes and management of respiratory failure

List indications/contraindications/complications of non invasive ventilation and understand its set up and monitoring

Definition:

Acute respiratory failure occurs when pulmonary system is no longer able to

meet the metabolic demands of the body

Type 1 Respiratory Failure Hypoxaemic

pO2 < 8 kPa ON AIR pCO2 < 6.0 kPa

Type 2 Respiratory FailureHypercapnic

pO2 < 8 kPa ON AIR pCO2 > 6.0 kPa

Clinical signs:

1. Respiratory compensation Tachypnoea Accessory muscles Recession Nasal flaring

2. Sympathetic stimulation HR BP (early) sweating

3. Tissue hypoxia Altered mental state HR and BP (late signs)

4. Haemoglobin desaturation:

(SpO2 < 90%)

Case 1 70 year old man referred to A&E by his GP PC: SOB and productive cough 4/7 HPC: gradual onset over 4-6/12 but worse over the last

3-4 days. SH: smoking 30 pack years.

O/E: O2 sats are 91% on air, RR 26, temp 37.8, BP 130/75, HR 89. Pt’s chest shows widespread bilateral wheeze throughout, reduced air entry LLL.

1. List your differential diagnosis and investigation tests.2. What would be your initial management of this patient?

ABG:

pH 7.31

pO2 8.4 kPa (on 6L O2)pCO2 5.9 kPa, HCO3- 21 mmol/l

Lac 3.1

What is your interpretation?

Initial management:

Investigations: ABG FBC, U&E, LFTs Peak flow CXR ECG Sputum and Blood

culture Urine dip, Urine

Microscopy

Treatment: A-E - Sepsis! Oxygen – high flow

initially, considercontrolled to aim O2Sat88-92% when stable

Nebulised bronchodilators

Steroids Antibiotics Fluids

COPD – Background:

Definition: COPD is predominantly caused by smoking and is characterised by airflow obstruction that: is not fully reversible and is usually progressive in the long term

COPD acute exacerbations: Increasing dyspnoeaIncreasing sputum volumeIncreasing sputum purulence (change in character)

Differentiating COPD from asthma

Clinical features COPD Asthma

Smoker or ex-smoker Nearly all Possibly

Symptoms under age 35 Rare Often

Chronic productive cough Common Uncommon

Breathlessness Persistent and progressive Variable/Intermittent

Night time waking with breathlessness and or wheeze

Uncommon Common

Significant diurnal or day to day variability of symptoms

Uncommon Common

Asthma – Background:

More than one of the following symptoms: Wheeze, cough, difficulty breathing, frequent and

recurrent chest tightness, worse at night and in the early morning;

Occur in response to, or are worse after, exercise or other triggers,

Personal/ Family history of atopic disorder and/or asthma

Widespread wheeze heard on auscultation History of improvement in symptoms or lung

function in response to adequate therapy.

Severe Asthma LIFE THREATENING PEF <33% best or predicted SpO2 <92% PaO2 <8 kPa normal PaCO2 (4.6-6.0

kPa) silent chest cyanosis poor respiratory effort arrhythmia exhaustion, altered

conscious level BP low

NEAR FATAL Raised PaCO2 and/or

requiring mechanical ventilation with raised inflation pressures

Criteria for Referral to ITU

Refer any patient: requiring ventilatory support with acute severe or life threatening asthma, failing to respond to therapy, evidenced by:

- deteriorating PEF

- persisting or worsening hypoxia

- hypercapnea

- ABG analysis showing low pH

- exhaustion, feeble respiration

- drowsiness, confusion, altered conscious state

- respiratory arrest

Case 2 17 y.o. female student PC: severe SOB, can not speak in full sentences HPC: woke up at 4 am feeling SOB and started

coughing, her housemate called ambulance PMH: too breathless to give O/E: Pt agitated, wide spread audible wheeze bilaterally,

poor chest expansion, using accessory muscles, HR 100, BP 130/85, T 36,6, O2 sat 93%

What would be your differential diagnosis and initial management?

ABG:

pH 7.46pO2 8.2 kPa (on 15L O2)pCO2 2.8 kPa, HCO3- 18 mmol/l

What is your interpretation?

Initial Management

Oxygen – high flow 15LNebulised bronchodilators Peak flowABGFBC, U&E, LFTs, Steroids

Case 3 76 year old male PC: SOB, 7/7 productive cough with phlegm PMH: known COPD, LTOT at home 2L for 16/24. On admission: RR 18, sats 85% on 2L oxygen,

HR 110, BP 134/68, temp 38.5. RLL crackles, but widespread wheeze throughout both lung fields.

The paramedics gave him 5ml salbutamol nebs and 100mg IV hydrocortisone an hour ago, he was given IV abx first dose, but he is not improving as yet, but become drowsy

What would be your management?

ABG: pH 7.23pO2 8.3kPapCO2 8.4kPa, HCO3- 24 mmol/lLac 4

Vitals:RR 12O2 Sats 90% on 4L oxygenHR 115BP 115/68

FBC:

Hb 16 g/dL

WCC: 18 × 109 /L

Neutrophils 80%

U&E:

Na 143 mmol/

K 4.6 mmol/L

Creat 120 μmol/L

Urea 8.2 mmol/L

What next?

Continue Nebulised Salbutamol

NIV (non-invasive ventilation)

NIV – non-invasive ventilation

Definition: Definition:

NIV is the delivery of mechanical NIV is the delivery of mechanical ventilation to the lungs using ventilation to the lungs using techniques that do not require an techniques that do not require an endotracheal airwayendotracheal airway

Types:

Continuous Positive Airway Pressure CPAP

Treating Hypoxia Type 1 RF

Bi-level Positive Airway Pressure (VPAP/Stellar)

Treating Hypercapnia Type 2 RF

Main goals of NIV

Correction of abnormalities in ABG’s (hypoxia and hypercapnia)

Maintaining alveolar ventilation and lung volume

Reduce the work of breathing Avoiding respiratory muscle fatigue

NIV does not correct underlying disorder or condition!

Medical conditions/Indications:

Acute exacerbation of COPD

(pH 7.26 – 7.35 or patients with NIV as ceiling of care and considered not suitable for HDU/ITU care)

Morbid Obesity / Severe OSA / Alveolar Hypoventilation Syndrome

Chronic Neuromuscular Disease Kyphoscoliosis / Chest wall deformity.

NIV contraindications: Respiratory arrest Undrained pneumothorax Impaired consciousness/confusion/aggressive

behaviour Chest wall trauma Uncontrolled vomiting/distended abdomen/

excessive secretions Facial trauma/surgery, burns or facial abnormalities

that are likely to cause difficulty with appropriate mask fit.

Recent upper abdominal surgery or intestinal obstruction.

Starting NIV: Locations:

HDU/ITU, Respiratory ward A+E resus (Not usually on a general ward – the nursing staff will not know how to deal with it)

Settings: • Should be prescribed by a consultant

Monitoring NIV:

Main actions:• Baseline ABG, RR, HR• Repeat ABG after one hour of starting• After every setting change, repeat ABG at 1 hour• Otherwise, every 4 hours, or if not well

Key points:• Aim minimum 6 hours treatment• Most people better by 24 hours on NIV• Weaning thereafter

Complications of NIV:

Pneumothorax, Decreased pre-load – may drop BP Increased risk of aspiration Face mask discomfort Anxiety + confusion

Key message

Common contributors to RF Type 1 (↓O2): Asthma and COPD Type 2 (↓O2 and ↑CO2): COPD and life

threatening asthma

NIV is effective in treating ↑CO2

Summary

worry if RR > 30/min (or < 8/min) unable to speak 1/2 sentence without pausing agitated, confused or comatose cyanosed or SpO2 < 90% deteriorating despite therapy

remember normal SpO2 does not mean severe ventilatory

problems are not present

Thank you!

Any questions?