1. Simon Barry Cardiff November 2015
NIV
Simon Barry
Cardiff November 2015

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

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

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

6. 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

7. 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

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

9. Ventillatory Failure
Caused by inadequate alveolar ventilation

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

11. Clinical examples VT RR VD
Opiate
overdose
Pulmonary
fibrosis
COPD

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

13. 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

14. 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

15. 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

16. 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

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

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

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

21. Disease Categories in Europe
Eurovent
Lloyd Owen 2002

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

27. 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

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