Simon Barry Cardiff November 2015 NIV Simon Barry Cardiff November 2015

NIV What is it? How does it work? What is the evidence? What are we doing in Wales? The future

Respiratory Failure Oxygenation Failure PaO2 <8 KPa Ventilation Failure PaCO2 > 6 KPa CPAP + oxygen Ventilation

Ventilation Invasive Non-invasive Tracheostomy ETT Positive Negative Pressure Volume Iron lung Cuirasse

NIV mechanisms How does NIV (usually at night) improve daytime gases and symptoms? Hill (1993): 1. increase ventilatory sensitivity to CO2 during spontaneous breathing 2. Rest respiratory muscles and increase their strength and endurance 3. Improve pulmonary mechanics by increasing compliance and lung volumes

Mechanisms of improvement in respiratory failure in patients with restrictive disease treated with NIV Nickol et al Thorax 2005 N= 20 (12 neuromuscular, 8 kyphoscoliosis) Improvement in daytime PCO2 at D5 and 3M associated with increased hypercapnoic ventilatory response No change in inspiratory muscle strength inc diaphragmatic twitch, lung function or chest wall compliance

Effect of NIV on hypercapnic ventilatory response (HCVR) in patients with neuromuscular weakness (open circles) and kyphoscoliosis (closed triangles). Nichol et al thorax 2005

Ventillatory Failure Caused by inadequate alveolar ventilation

Alveolar hypoventilation VA = VE-VD VE = minute ventilation VD = dead space ventilation VE = tidal volume (VT) x RR

Clinical examples VT RR VD Opiate overdose Pulmonary fibrosis COPD

Important physiological effects of NIV Correction of acidosis (Henderson Hasslebach) pH ~ HCO3/PCO2 Improvement in oxygenation (Alveolar gas equation) PAO2 ~ FiO2 – PCO2/0.8

When to Use NIV Acute ventilatory failure (excellent evidence for COPD) Chronic ventilatory failure (neuromuscular, obesity, chest wall) Sleep apnoea uncontrolled by CPAP Early extubation ITU

NIV in AECOPD- the evidence Multicentre RCT ward based NIV Inclusion COPD, pH<7.35, PCO2>6 NIV vs standard therapy in acute type 2 RF N= 236 Intubation 27% vs 15% p=0.02 In hospital mortality 20% vs 10% p=0.05 Improvements in pH, RR and dyspnoea Plant et al Lancet 2000; 355:1931-5

AECOPD pH<7.2 pH<7.3 pH<7.35 Plant et al Lancet 2000; 355:1931-5 AECOPD Controlled oxygen Target sats 88-92% Repeat ABG pH<7.2 50% need intubation Despite NIV pH<7.3 50% will deteriorate Without NIV pH<7.35 80% will recover with Standard therapy NNT 10 to prevent 1 intubation NIV on HDU NIV on ward

NIV in chronic COPD N=144 NIV + LTOT vs LTOT FEV1 25%, BMI 25, PCO2 7.4 Pressures 13/5 Slight improvement survival Worse QOL

Survival in MND: NIV vs control Median survival 219 vs 171 days N=41 Bourke et al Lancet Neurology 2006

Quality of Life in MND: NIV vs control Bourke et al Lancet Neurology 2006

Trends in survival in Duchenne MD Eagle et al Neuromusc Dis 2002

Disease Categories in Europe Eurovent Lloyd Owen 2002

NIV in Wales All wales NIV meetings Acute NIV guidelines Chronic NIV guidelines Variability in nurse specialist support Variability in ward based NIV/NIVunit

The Future All Wales database for NIV patients Virtual clinics HB agreement for adequate respiratory nurse support Support for level respiratory units in larger hospitals

NIV Pearls Early recognition: Acute ventilatory failure is a medical emergency Early use of NIV and rapid escalation of pressures Staff training The interface