This is a case based discussion about non invasive ventilation in patients with acute exacerbation of COPD

1. Pulmonary and critical care Medicine - Case
Discussion : A 56 year old man was admitted
with acute exacerbation of COPD
Dr. Atanu Chandra
MD(Medicine);DNB(Medicine);MRCP(UK)
Assistant Professor , Dept. of Medicine , R G Kar Medical College ,
Kolkata
APICON 2020
75th Annual Conference of
The Association of Physicians of India
Platinum Jubilee Conference
6th – 9th January, 2020, Agra

2. Problem
• A 56 year old man was admitted with acute exacerbation of COPD.
• Apart from being tachypneic and having sinus tachycardia, patient was
conscious and well oriented.
• ABG shows:
pH- 7.164
PO2-53
PCO2-89
HCO3- 31
• SpO2 82% (with 2l/min moist O2)
• What should be the mode of ventilation – NIV/Mechanical invasive
ventilation and why ?

3. Validity Check
• H+ Conc.=24(PaCO2/HCO3-)[Henderseon-Hasselbach equation]
In our case it is-24×(89/31)=69 mmol/L
• If the pH & H+ Conc. is inconsistent, then the ABG is not probably
valid.
• So this ABG is a valid one.
pH Approximate H+[In mmol/L]
7.00 100
7.05 89
7.10 79
7.15 71
7.20 63

4. Key Points
• Acute exacerbation of COPD.
• Patient was conscious and well oriented with no signs of
hemodynamic instability
• Type 2 respiratory failure (PCO2=89mm Hg)
• Respiratory Acidosis (pH-7.16) with metabolic compensation
• No improvement on moist oxygen inhalation (2L/min)

5. What To Do
NONINVASIVE VENTILATION
Vs
INVASIVE VENTILATION

7. STANDARD MEDICAL THERAPY
• Controlled oxygen to maintain SpO2 88-92%
• Nebulised Salbutamol
• Nebulised ipratropium
• Steroids
• Antibiotics(when indicated)

8. INDICATIONS OF NIV IN COPD
• Respiratory acidosis(PaCO2> 6kPa or 45mmHg & arterial pH<7.35)
• Severe dyspnea with clinical signs suggestive of respiratory muscle fatigue,
increased work of breathing or both.
• Persistent hypoxemia despite supplemental oxygen therapy.
GOLD-Global Strategy for the diagnosis , management & prevention of COPD(2020 report)

9. INDICATIONS FOR MECHANICAL VENTILATION
• Unable to tolerate NIV or NIV failure
• Status post-respiratory or cardiac arrest
• Diminished consciousness/Psychomotor agitation not controlled by sedation
• Massive aspiration or persistent vomiting
• Severe hemodynamic instability without response to fluids or vasopressors
• Severe ventricular or supra-ventricular arrhythmias
• Life threatening hypoxemia in patients unable to tolerate NIV
GOLD-Global Strategy for the diagnosis , management & prevention of COPD(2020 report)

10. PATIENT SELECTION
• Premorbid State
• Severity of Physiologic disturbances
• Sensorium
• Ability to protect airways
• Potential recovery
• Patient’s wishes to be considered

11. Basics of NIV(BIPAP)
• Patient's inspiratory effort stimulates the switch between EPAP and
IPAP.
• As the inspiratory phase cycles off, the machine shifts again to EPAP
• Start with inspiratory pressure of 8–12 mm Hg and expiratory pressure
of 3–5 mm Hg. The pressure support (PS) obtained is the same as the
difference between the two settings.
• Dyspnoea is mitigated by elevation of inspiratory pressure. Elevated
expiratory pressure enhances oxygenation.

12. BiPAP Machine & Interfaces

13. Protocol for initiation of NIV
• Patient in bed or chair sitting at > 30‐degree angle
• A full‐face mask be used initially as interface.
• Connect interface to ventilator tubing and turn on ventilator
• Check for air leaks, readjust straps as needed
• Monitor occasional blood gases (within 1 to 2h and then as needed)
BTS/ICS guideline for the ventilatory management of AHRF in adults(April 2016)

14. Guidelines for providing NIV
• An initial IPAP of 10 cm H2O & EPAP of 4–5 cm H2O
• IPAP increased by 2–5 cm increments @ 5 cm H2O every 10mins, with a
usual IPAP target of 20 cm H2O or until a therapeutic response is achieved or
patient tolerability has been reached
• O2 should be entrained into the circuit and the flow adjusted to SpO2 >88–
92%
• Bronchodilators– preferably administered during breaks from NIV & if
necessary be entrained between the expiration port and face mask
BTS/ICS guideline for the ventilatory management of AHRF in adults(April 2016)

15. Monitoring
• Subjective responses
• Physiologic response
– ↓ RR, ↓ HR, BP, cont. ECG (specially if HR>120bpm/dysrhythmia)
– Patient breath in synchrony with the ventilator
– ↓ accessory muscle activity and abdominal paradox; Monitor air leaks
• Gas exchange
– Continuous SpO2 and ECG during the first 12 hours
• ABG- After 1 hour of NIV therapy and 1 hour after every
subsequent change in settings
• After 4 hours, or earlier in patients who are not improving clinically

16. TERMINATION OF NIV
• NIV can be discontinued when normalisation of pH & PaCO2 with general
improvement in patient’s condition.
• Time on NIV should be maximized in first 24 hours.
• Treatment should last until the acute cause has resolved, commonly after
about 3 days
• When NIV is successful (pH>7.35,resolution of cause, normalisation of
RR) after 24 hrs/more – plan weaning
BTS/ICS guideline for the ventilatory management of AHRF in adults(April 2016)

17. Rationale Of NIV(BIPAP) in COPD
• Several RCT’s and meta-analyses found a reduction in intubation rate, hospital-
acquired pneumonia and mortality.
• Acute exacerbations (AE) of COPD patients have an increased work of breathing,
muscle fatigue, and respiratory acidosis
• The pressure support with NIV
 Unload respiratory muscles
 External PEEP applied to the lung assists the patient to overcome intrinsic PEEP

18. Recommendations
• NPPV in A/E COPD recommended in ARF when pH is 7.25–7.35 and PaCO2 is
>45 mm Hg, despite standard medical therapy.
• Bilevel NIV decreases need for urgent intubation, length of hospital stay,
especially in ICU, and reduces chances of infection and enhanced survival rate.
• There is no lower limit of pH
• Lower the pH, the greater is the risk of failure, & patients must be very closely
monitored with rapid access to invasive ventilation if not improving.
• Severe acidosis (i.e. pH <7.26) and delayed treatment initiation led to NIV
failure.
BTS/ICS guideline for the ventilatory management of AHRF in adults(April 2016)

19. PREDICTORS OF NIV SUCCESS
• Lower acuity of illness (APACHE score)
• Ability to cooperate; better neurologic score
• Ability to coordinate breathing with ventilator
• Less air leakage; intact dentition
• Hypercarbia, but not too severe (PaCO2 between 45 and 92 mm Hg)
• Acidosis, but not too severe (pH between 7.1and 7.35)
• Improvements in gas exchange ,HR & RR within first 2 hours

20. DISADVANTAGES OF NONINVASIVE
VENTILATION
System
• Slower correction of gas exchange abnormalities
• Time commitment/attention
• Gastric distention
Interface
• Leaks
• Skin necrosis/rash
• Eye/ear irritation
• Sinus pressure
Airway
• Aspiration
• Limited secretion clearance.

21. NIV Vs Invasive Ventilation
• NIV is preferred over invasive ventilation as the initial mode of
ventilation in A/E COPD.
• NIV has shown success rate of 80-85%
• NIV improves oxygenation and acute respiratory acidosis
• NIV also decreases respiratory rate, work of breathing and severity of
breathlessness
• It reduces the complications of invasive ventilation and also length of
hospital stay.

22. Ideal Mode of Ventilation In Our Case
Problems
• Acute exacerbation of COPD
• Patient was conscious and
hemodynamically stable
• Type 2 respiratory
failure(PCO2=89mm Hg)
• Respiratory Acidosis(pH-7.16)
with metabolic compensation
• NIV is the preferred initial mode of
ventilation
• No lower limit of pH for NIV. But,
lower the pH, greater the risk of
failure
• Important to make decision when to
switch to invasive mechanical
ventilation in NIV failure.

23. TAKE HOME MESSAGE
• NIV- Ideal initial mode in COPD with ARF & respiratory acidosis(PaCO2>
45mmHg & arterial pH<7.35)
• It decreases need for urgent intubation, length of hospital stay , infection and
enhanced survival rate.
• There is no lower limit of pH . But lower the pH, the greater is the risk of failure
• Switch to invasive ventilation in NIV failure (Worsening pH and PaCO2 ;
Hemodynamic instability ;Decreased level of consciousness ; Inability to clear
secretion/tolerate interface)
• NIV has shown success rate of 80-85%

24. THANK YOU