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Ventilatory support in special situations. Dr.Balamugesh.T, MD, DM Dept. of Pulmonary Medicine, CMC, Vellore. 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 2:7. ARDS COPD Bronchial asthma

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ventilatory support in special situations

Ventilatory supportin special situations

Dr.Balamugesh.T, MD, DM

Dept. of Pulmonary Medicine,

CMC, Vellore.


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 2:7

  • COPD
  • Bronchial asthma
  • Bronchopleural fistula
  • Acute onset
  • Hypoxia- PaO2/FiO2<200
  • Bilateral infiltrates on CXR
  • Absence of left atrial hypertension

Mortality - 26% to 74%

ventilation induced lung injury
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
ventilation in ards
Ventilation in ARDS
  • Which mode?
  • How much FiO2?
  • How much PEEP?
  • How much VT?
  • Target?
  • What if refractory ARDS?
which mode
Which mode?
  • Volume assist/control commonly used
  • Plateau-pressure goal ≤30 cm of water

ARDS Clinical Trials Network

how much fio2
How much FiO2?
  • Least FiO2 to achieve Oxygenation goal
    • PaO2 55–80 mm Hg
    • SpO2 88–95%
  • FiO2 > 60% risk of oxygen toxicity.
how much tidal volume ards network
How much Tidal volume? ARDS Network


  • Low tidal volume -31%

(6 mL/kg predicted body weight)

  • Conventional tidal volume -40%

(12 mL/kg)

  • 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
open lung ventilation olv
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
  • The lower inflection point on the static pressure–volume curve represents alveolar opening (or “recruitment”).
  • “optimal PEEP” - The pressure just above this point, is best for alveolar recruitment
  • usually 10 to 18 mmHg

optimal PEEP

J J Cordingley, Thorax 2002;57

how much peep
How much PEEP?
  • Low PEEP(8.3±3.2 cm of water)
  • High PEEP (13.2±3.5 cm)

No difference in outcomes if VT- 6ml/kg and Plat. Pressure <30cm

N Engl J Med 2004;351

permissive hypercapia
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
protective lung ventilation protocol from the ardsnet study
Protective lung ventilation protocol from the ARDSNet study
  • Initial tidal volume – 6ml/kg
  • Plat. Pressure <30cm H20
  • Oxygenation goal PaO2 = 55 - 80 mmHg or pulse oximetry oxygen saturation 88–95%
  • I:E ratio 1:1–1:3
  • Goal arterial pH = 7.30–7.40 
    • If pH < 7.30, increase respiratory rate up to 35 breaths/min 
    • If pH < 7.30 and respiratory rate = 35, consider starting intravenous bicarbonate
refractory hypoxia
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
prone position ventilation
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

recruitment manoeuvres
Recruitment manoeuvres
  • Sigh function in ventilators
  • By ambu bag
  • Sustained inflation or CPAP of 30-45 cm H20 for 20-120 sec.
inverse ratio ventilation
Inverse ratio ventilation
  • Prolongation of the inspiratory time as a method of recruitment
  • Pressure control ventilation to increase the I:E ratio to 1:1 or 2:1
  • hyperinflation and the generation of intrinsic PEEP
think twice
Think twice
  • Reversibility of the precipitating event,
  • Patient’s/relative’s 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

post intubation hypotension
Post-Intubation hypotension
  • Reduced venous return secondary to positive intrathoracic pressure due to bagging
  • Direct vasodilation and reduced sympathetic tone induced by sedative agents
mechanical ventilation
Mechanical ventilation
  • Avoid overcorrection of respiratory acidosis and life threatening alkalosis.
  • Prolonged expiratory time. I:E – 1:2.5 to 1:3.
  • Low Respiratory Rate- 10-14/mt.
  • Limited tidal volume
  • 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
post extubation niv
Allow early extubation

Prevent post extubation respiratory failure

Post extubation NIV
niv in asthma
NIV in asthma
  • Few trials
  • Trial of NIV over 1–2 hours in an ICU if there are no contraindications
niv in acute bronchial asthma
NIV in acute bronchial asthma
  • FEV1<40%, PaCO2 <40mm Hg
  • Conventional medical management Vs BiPAP 15/5 for 3 hours

Chest. 2003;123

niv in asthma1
NIV in asthma….
  • 80% NIV group increased FEV1 by >50% as compared to baseline, vs 20% of control patients (p < 0.004)
  • alleviate the attack faster, and
  • significantly reduce the need for hospitalization.
endotracheal intubation
Endotracheal intubation
  • Absolute indications
    • Cardiopulmonary arrest and
    • Deteriorating consciousness
  • Relative
    • Progressive deterioration, hypercapnia with increasing distress or physical exhaustion
Intubation performed/supervised by experienced anaesthetists or intensivists
  • Use larger endotracheal tube

• FiO2= 1.0 (initially)

• Long expiratory time (I:E ratio >1:2)

• Low tidal volume 5–7 ml/kg

• Low ventilator rate (8–10 breaths/min)

• Set inspiratory pressure 30–35 cm H2O on pressure control ventilation or limit peak inspiratory pressure to <40 cm H2O

• Minimal PEEP <5 cm H2O

aerosol delivery
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

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

Air escaping through the BPF
    • delays healing of the fistulous track
    • significant loss of tidal volume, jeopardizing the minute ventilation and oxygenation
measures to reduce air leak
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,
chest tube
Chest tube
  • To add positive intrapleural pressure during the expiratory phase to maintain PEEP
  • Occlusion during the inspiratory phase to decrease BPF flow
high frequency ventilation hfv
High-frequency ventilation (HFV)
  • Useful in patients with normal lung parenchyma and proximal BPF
  • Limited value in patients with distal disease and parenchymal disease.