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Spontaneous breathing in ARDS
Alain Mercat
Conflicts of interests
• Fundings for clinical researchs
• Covidien (PAV+)
• GE (EELV/PEEP/ARDS)
• Maquet (NAVA)
• Fisher-Paykel (Optiflow)
• Patent
• GE (EELV/PEEP/recruitment)
• Fees for lectures
• Covidien
• Fisher Paykel
• Fees for consulting
• Faron Pharmaceuticals
• Air Liquide Medical Systems
Controlled ventilation in ARDS
Heavy sedation +/- paralysis
Benefits Drawbacks
VO2 and VCO2
ventilatory requirementsImpaired hemodynamics
Control of tidal volume,
plateau and driving pressure
Prevention of « VILI »
Uneven distribution of VT,
monotony
Avoid agitation and
asynchrony
Atrophy and weakness of
respiratory muscles (VIDD)
• More homogeneous distribution of lung aeration
Decreased VILI
Improved gas exchanges
• Decreased duration of diaphragmatic inactivity
Protection against VIDD
• Decreased intrathoracic pressure
Improved hemodynamics
• Decreased need for sedation
Earlier weaning
Spontaneous breathing in ARDS : Benefits
Mechanical breath vs spontaneous breath
Mechanical breath
Spontaneous breath
Abdominal
pressure
Abdominal
pressure
Lower transpulmonary pressure in the
lower part of the lung (lung weight).
Increased transpulmonary pressure in
the lower part of the lung
(diaphragmatic contraction).
(12 ± 2 cmH20) (3 ± 2 cmH20)
10 ml/kg/IBW
6 ml/kg/IBW
4 ml/kg/IBW
APRV BIPAP PAC
Spontaneous breaths, not assisted breaths
Richard et al. Intensive Care Med. 2013;39:2003-10
Spontaneous breaths, not assisted breaths
Richard et al. Intensive Care Med. 2013;39:2003-10
0
100
200
300
400
500
600
700
0 0.5 1 1.5 2 2.5 3 3.5
0
10
20
30
40
50
60
vt
CV
APRV BIPAP PAC
Crit Care Med. 2016
« Optimized positive end-expiratory
pressure decreased the magnitude of
spontaneous efforts despite using less
sedation, …, while concomitantly reducing
pendelluft and tidal recruitment. »
Anesthesiology 2014
APRV with 1/1 or 1/2 IE ratio
0
40
80
120 PaO2 (mmHg)
*
0
5
10
15
20
25
30
35
Pressuresupport
PressureControl
BIPAP-APRVwith SB
Shunt (%)
*
*
3
4
5
6
Pressuresupport
PressureControl
BIPAP-APRVwith SB
Cardiac index (L/min/m2)
*
6
7
8
9
10
11
12
Pressuresupport
PressureControl
BIPAP-APRVwith SB
Mean Peso (cmH2O)
Levine et coll. New Engl J Med 2008
MV : 18 - 69 hr MV : 2 - 3 hr
Diaphragmatic inactivity « VIDD »
Gayan-Ramirez et coll. Crit Care Med 2005
Spontaneous breathing prevents VIDD
Inspiratory efforts prevent diaphragmatic atrophy
Goligher et al. AJRCCM 2015
« Changes in diaphragm configuration associated with mechanical ventilation
might be prevented by titrating ventilatory support to maintain normal levels of
respiratory effort. »
Spontaneous breathing in ARDS
• Animal and clinical studies suggest physiological benefits
• A mode without any synchronization should be prefered
(spontaneous breaths, not assisted breaths)
• With a sufficient level of PEEP (high PEEP strategy)
• Excessive ventilatory efforts should be avoided (sedation)
• The benefit on outcome remains to be demonstrated
Birds trial
- A. Mercat, JC. Richard, L. Brochard,
- Multicenter RCT : 700 patients with moderate or severe ARDS
- ACV vs « BIPAP / APRV » (SB = 10 to 50 % of total ventilation)
- Same VT 6 ml/kg PBW, same PEEP (« ExPress »)
- Same strategies for sedation and weaning
- Primary endpoint : hospital mortality
Birds : Management of spontaneous ventilation
Spontaneous Ventilation = 10 à 50 % of VM tot
SV < 10%
and
RASS < -2
SV < 10%
and
Sedation OK
SV > 50%
and
Sedation OK
SV > 50%
and
RASS > -2
Sedation Alcalosis?
If yes
Increase Tlow
(RR)
SedationAcidosis ?
If yes
decrease Tlow
(RR)
If T° > 38°C +/- cooling
Check goals (Spontaneous Vent and Vt ) every 8 or 12 h
BIPAP- APRV = Pressure Control + SB
Flow
Paw
Peso
