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NIV Why? How?. Non Invasive Ventilation – a guide to difficult choices Dr Sanj Fernando.

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Presentation on theme: "NIV Why? How?. Non Invasive Ventilation – a guide to difficult choices Dr Sanj Fernando."— Presentation transcript:

1 Non Invasive Ventilation – a guide to difficult choices Dr Sanj Fernando

2 NIV Why? How?

3 Respiratory Failure Ventilation Failure Gas exchange Failure
Forces resisting ventilation > Forces of respiratory effort Ventllation failure Forces resisting ventilation: Elastic recoil of lungs Airway (+ tubing) resistance Intrinsic PEEP Intrinsic vs extrinsic PEEPi Absent in healthy lung Caused by Tachypnoea Airflow obstruction (small airway) Gas exchange failure Alveolar problem Stuff in the alveoli APO Pneumonia Decreased alveoli COPD Alveolar-Blood barrier problem Thickened barrier – connective tissue disorders Circulation problem VQ mismatch Blood problem Decreased oxygen content Anaemia Haemoglobinopathy (thalassaemia, methaemaglobinaemia) Red cell disorder (sickle cell) Decreased Alveolar function / Circulation problem

4 68 yo man arrives at 6:30 am Awoke with SOB, mild chest pain Sweaty +++ Smoker + previous MI RR=40 Tripod posture Sats = 91% on NRB

5 What are we trying to achieve with NIV?
Improve alveolar ventilation Reverse hypercarbia and acidosis Alveolar recruitment and increased FiO2 Reverse hypoxia Reduction in work of breathing Reduce respiratory muscle insufficiency Decrease metabolic demands Reduction in LV afterload and preload Improved cardiac function

6 CPAP vs PEEP vs IPAP vs BiPAP
PEEP=EPAP=CPAP + IPAP = BiPAP BPAP} BiPAP®} Bilevel => NIV <= CPAP = EPAP = PEEP BIPAP®} CPAP 1 pressure5-10cmH2O Prevent alveolar collapse Clear mucus Alveolar recruitment and splinting Oxygenate better Decrease Work of breathing Increase intrathoracic pressure (good – dec. cardiac work; bad – may drop BP) BiPAP 2 pressures IPAP = 10 EPAP = 5 = PEEP = CPAP 10-5 = 5 cmH2O = Pressure support Pressure support => important for improving ventillation Better ventillation Decrease CO2 Decrease acidosis If high CO2 – increase IPAP and PS If low O2 – increase EPAP and FiO2 Remember if you increase EPAP without increasing IPAP => decrease Pressure support and decrease ventillation

7 CPAP vs PEEP vs IPAP vs BiPAP
If high CO2 : increase IPAP and PS If low O2 : increase EPAP and FiO2 PEEP=EPAP=CPAP + IPAP = BiPAP BPAP} BiPAP®} Bilevel => NIV <= CPAP = EPAP = PEEP BIPAP®} CPAP 1 pressure5-10cmH2O Prevent alveolar collapse Clear mucus Alveolar recruitment and splinting Oxygenate better Decrease Work of breathing Increase intrathoracic pressure (good – dec. cardiac work; bad – may drop BP) BiPAP 2 pressures IPAP = 10 EPAP = 5 = PEEP = CPAP 10-5 = 5 cmH2O = Pressure support Pressure support => important for improving ventillation Better ventillation Decrease CO2 Decrease acidosis If high CO2 – increase IPAP and PS If low O2 – increase EPAP and FiO2 Remember if you increase EPAP without increasing IPAP => decrease Pressure support and decrease ventillation

8 Cardiogenic Pulmonary Oedema
CPAP BiPAP Movement of lung water into interstitium + surfactant production Provides no clear advantage May increase rate of MI Recruits alveoli Sufactant production Reverses hypoxia Decreases VQ mismatch Reduces preload and afterload and myocardial catecholamine release increase in elastic recoil due to lung water and decreased surfactant Barrier to alveolar gas exchange Optimal CPAP pressure ?10cm H2O

9 COPD BiPAP recommended Number needed to treat to prevent death – 10
Both CPAP to recruit alveoli and IPAP to improve ventilation and decrease respiratory muscle work are useful Optimal settings Inspiratory support – 5-15 cm H2O CPAP – 4-8 cm H2O Increase incrementally to aid recruitment FiO2 titrated to lowest level to prevent hypoxia Primarily an increase in resistance to airflow – causes PEEPi Number needed to treat to prevent death – 10 Number needed to treat to prevent intubation – 4 Ram FSF, Picott J, etal. Noninvasive positive pressure ventilation for treatment of respiratory failure due to exacerbations of chronic obstructive pulmonary disease. Cochrane database of Systematic reviews 2004

10 Asthma Similar to COPD CPAP well established to be of benefit
BiPAP has been shown to provide benefit but less well established Optimal settings CPAP – 5cm H2O in moderate to severe asthma BiPAP titrated settings over min FiO2 titrated to lowest level to prevent hypoxia

11 ARDS Little objective evidence High failure rate

12 Community Acquired pneumonia
Intensive Care Medicine Journal 184 consecutive patients March 2012 NIV is more helpful if underlying cardiorespiratory disease Abandon NIV if after 1 hr: Higher heart rate Lower PaO2/FiO2 Lower bicarb

13 NOT SURE! Prepare patient!!! Take time to get the right mask
Consider FiO2 needed Start at BiPap = 10/5 cm H2O or CPAP = 5 cm H2O Increase pressures by 2-3 cm H2O every 5-10m until satisfactory response – (max 15cm H2O)

14 68 yo man arrives at 6:30 am Awoke with SOB, mild chest pain Sweaty +++ Previous MI RR=40 Tripod posture Sats = 91% on NRB

15 CPAP At 5 cmH2O and FiO2= 25% O2 = 55 CO2 = 72

16 BiPAP I/E=12/6 FiO2 = 30% PaCO2= 72, PaO2 = 145 I/E=14/6 FiO2 = 24%

17 GETTING OFF NIV If patient condition improves markedly , NIV can be stopped abruptly Typical trial periods of 1 hr on 2 hrs off etc

18 When NOT to use NIV

19 Take home mesage If high CO2 : increase IPAP and PS If low O2 :
increase EPAP and FiO2 PEEP=EPAP=CPAP + IPAP = BiPAP BPAP} BiPAP®} Bilevel => NIV <= CPAP = EPAP = PEEP BIPAP®} CPAP 1 pressure5-10cmH2O Prevent alveolar collapse Clear mucus Alveolar recruitment and splinting Oxygenate better Decrease Work of breathing Increase intrathoracic pressure (good – dec. cardiac work; bad – may drop BP) BiPAP 2 pressures IPAP = 10 EPAP = 5 = PEEP = CPAP 10-5 = 5 cmH2O = Pressure support Pressure support => important for improving ventillation Better ventillation Decrease CO2 Decrease acidosis If high CO2 – increase IPAP and PS If low O2 – increase EPAP and FiO2 Remember if you increase EPAP without increasing IPAP => decrease Pressure support and decrease ventillation


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