Ventilatory support in special situations

1
Ventilatory supportin special situations

• Dr.Balamugesh.T, MD, DM
• Dept. of Pulmonary Medicine,
• CMC, Vellore.

2
And the Lord God formed man of the dust of the
ground, and breathed into his nostrils and breath
of life, and man become a living soul.
Genesis 27
3

• ARDS
• COPD
• Bronchial asthma
• Bronchopleural fistula

4
ARDS

• Acute onset
• Hypoxia- PaO2/FiO2lt200
• Bilateral infiltrates on CXR
• Absence of left atrial hypertension

Mortality - 26 to 74
5
Eddy Fan, JAMA. 2005294
6
baby lung
Eddy Fan, JAMA. 2005294
7
Ventilation Induced Lung Injury

• Volutrauma over distention of alveoli
• Barotrauma high inflation pressures
• Atelectrauma - repetitive opening and closing of
  alveoli
• Biotrauma - up-regulated cytokine release
• Oxygen toxicity

8
Ventilation in ARDS

• Which mode?
• How much FiO2?
• How much PEEP?
• How much VT?
• Target?
• What if refractory ARDS?

9
Which mode?

• Volume assist/control commonly used
• Plateau-pressure goal 30 cm of water

ARDS Clinical Trials Network
10
How much FiO2?

• Least FiO2 to achieve Oxygenation goal
• PaO2 5580 mm Hg
• SpO2 8895
• FiO2 gt 60 risk of oxygen toxicity.

11
How much Tidal volume? ARDS Network
Mortality

• Low tidal volume -31
• (6 mL/kg predicted body weight)
• Conventional tidal volume -40
• (12 mL/kg)

12
PEEP

• Improves oxygenation by providing movement of
  fluid from the alveolar to the interstitial
  space,
• Prevent cyclical alveolar collapse
• Recruitment of small airways collapsed alveoli,
• Increase in FRC

13
Open Lung Ventilation (OLV)

• Objective - maintenance of adequate oxygenation
  and avoidance of cyclic opening and closing of
  alveolar units by selecting a level of PEEP that
  allows the majority of units to remain inflated
  during tidal ventilation
• Trade off - Hypercapnia

14
PEEP.

• The lower inflection point on the static
  pressurevolume curve represents alveolar opening
  (or recruitment).
• optimal PEEP - The pressure just above this
  point, is best for alveolar recruitment
• usually 10 to 18 mmHg

15
optimal PEEP
J J Cordingley, Thorax 200257
16
How much PEEP?

• Low PEEP(8.33.2 cm of water)
• High PEEP (13.23.5 cm)
• No difference in outcomes if VT- 6ml/kg and Plat.
  Pressure lt30cm

N Engl J Med 2004351
17
Permissive hypercapia

• usually well tolerated
• Consequences
• myocardial depression,
• Pulmonary hypertension
• Raised ICT
• Increase RR
• Judicious bicarbonate
• Tracheal gas insufflation to wash out dead
  space CO2

18
Protective lung ventilation protocol from the
ARDSNet study

• Initial tidal volume 6ml/kg
• Plat. Pressure lt30cm H20
• Oxygenation goal PaO2 55 - 80 mmHg or pulse
  oximetry oxygen saturation 8895
• IE ratio 1113
• Goal arterial pH 7.307.40 
• If pH lt 7.30, increase respiratory rate up to 35
  breaths/min 
• If pH lt 7.30 and respiratory rate 35, consider
  starting intravenous bicarbonate

19
Refractory hypoxia

• 1. Neuromuscular blocking agents (if not already
  in use)
• 2. Prone position ventilation
• 3. Recruitment maneuvers
• 4. Inverse ratio ventilation,
• 5. Miscellaneous
• nitric oxide,
• high-frequency ventilation,
• extracorporeal membrane oxygenation, or
• partial liquid ventilation

20
Prone position ventilation

• Improve oxygenation
• Better FRC
• Recruitment of dorsal lung
• Better clearance of secretion
• Better ventilation-perfusion matching
• Potential problems
• facial oedema, eye damage
• dislodgment of endotracheal tubes and
  intravascular catheters
• Difficulty in resuscitation

No differences in clinical outcome
21
Recruitment manoeuvres

• Sigh function in ventilators
• By ambu bag
• Sustained inflation or CPAP of 30-45 cm H20 for
  20-120 sec.

22
Inverse ratio ventilation

• Prolongation of the inspiratory time as a method
  of recruitment
• Pressure control ventilation to increase the IE
  ratio to 11 or 21
• hyperinflation and the generation of intrinsic
  PEEP

23
Obstructive lung disease

• COPD
• Asthma

24
Indications for NIV for AE-COPD
GOLD 2005
25
Exclusion criteria
GOLD 2005
26
Indications forInvasive Mechanical Ventilation
GOLD 2005
27
Think twice

• Reversibility of the precipitating event,
• Patients/relatives wishes, and
• Availability of intensive care facilities
• Failure to wean

Mortality among COPD patients with respiratory
failure is no greater than mortality among
patients ventilated for non-COPD causes
GOLD 2005
28
Post-Intubation hypotension

• Reduced venous return secondary to positive
  intrathoracic pressure due to bagging
• Direct vasodilation and reduced sympathetic tone
  induced by sedative agents

29
Mechanical ventilation

• Avoid overcorrection of respiratory acidosis and
  life threatening alkalosis.
• Prolonged expiratory time. IE 12.5 to 13.
• Low Respiratory Rate- 10-14/mt.
• Limited tidal volume

30
PEEP

• PEEPe beneficial
• Reduce gas trapping by stenting open the airways
• Reduce the work to trigger inspiratory flow
• As PEEPe is applied, tidal volume will increase
  without an increase in airway pressure until
  PEEPe exceeds PEEPi

31
Post extubation NIV

• Allow early extubation
• Prevent post extubation respiratory failure

32
Asthma
33
NIV in asthma

• Few trials
• Trial of NIV over 12 hours in an ICU if there
  are no contraindications

34
NIV in acute bronchial asthma

• FEV1lt40, PaCO2 lt40mm Hg
• Conventional medical management Vs BiPAP 15/5 for
  3 hours

Chest. 2003123
35
NIV in asthma.

• 80 NIV group increased FEV1 by gt50 as compared
  to baseline, vs 20 of control patients (p lt
  0.004)
• alleviate the attack faster, and
• significantly reduce the need for
  hospitalization.

36
Endotracheal intubation

• Absolute indications
• Cardiopulmonary arrest and
• Deteriorating consciousness
• Relative
• Progressive deterioration, hypercapnia with
  increasing distress or physical exhaustion

37

• Intubation performed/supervised by experienced
  anaesthetists or intensivists
• Use larger endotracheal tube

38
FiO2 1.0 (initially) Long expiratory time
(IE ratio gt12) Low tidal volume 57 ml/kg
Low ventilator rate (810 breaths/min) Set
inspiratory pressure 3035 cm H2O on pressure
control ventilation or limit peak inspiratory
pressure to lt40 cm H2O Minimal PEEP lt5 cm H2O
39
Aerosol delivery

• Metered dose inhaler (MDI) system
• Spacer or holding chamber
• Location in inspiratory limb rather than Y
  piece
• No humidification (briefly discontinue)
• Actuate during lung inflation
• Large endotracheal tube internal diameter
• Prolonged inspiratory time

40

• Jet nebuliser system
• Mount nebuliser in inspiratory limb
• Consider continuous nebulisation
• Increase inspiratory time and decrease
  respiratory rate
• Use a spacer
• Stop humidification
• Delivery may be improved by inspiratory
  triggering

41
Ventilator strategies in Bronchopleural fistula
42

• Air escaping through the BPF
• delays healing of the fistulous track
• significant loss of tidal volume, jeopardizing
  the minute ventilation and oxygenation

43
Measures to reduce air-leak

• Limit the amount of PEEP
• Limit the effective tidal volume,
• Shorten inspiratory time,
• Reduce respiratory rate.
• Use of double-lumen intubation with differential
  lung ventilation,

44
Chest tube

• To add positive intrapleural pressure during the
  expiratory phase to maintain PEEP
• Occlusion during the inspiratory phase to
  decrease BPF flow

45
High-frequency ventilation (HFV)

• Useful in patients with normal lung parenchyma
  and proximal BPF
• Limited value in patients with distal disease and
  parenchymal disease.