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Noninvasive Mechanical Ventilation,Prone position, surfactant and NO. Gül Gürsel Gazi University School of Medicine, ICU of Department of Pulmonary Diseases.
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Noninvasive Mechanical Ventilation,Prone position, surfactant and NO Gül GürselGazi University School of Medicine, ICU of Department of Pulmonary Diseases
The use of a low-tidal volume(6ml/kg predicted body weight), plateau pressure-limited strategy has been demonstrated to reduce mortality from 40 to 31%. Is there a role for NIMV in ARDS? Impact of fluid and catheter strategy on outcome. What is the role of prone position? Pharmacologic therapies?? Corticosteroids Surfactant NO
Is there a role for NIMV in ARDS? A meta-analysis Agarval et al Resp Med 2006
The addition of NIMV to standard care in the setting of ARDS did not reduce the rate of endotracheal intubation and had no effect on ICU survival
Exclusion criteria • Coma, seizures or nerological disturbances • Hemodynamic or ECG instability • Active bleeding • Need for endotracheal intubation (secretions, to protect airways) • Recent facial trauma, gastroesophageal surgery • More than 2 organ failures
During the 25 months • 5888 patients were admitted to the ICUs of the 3 centers • 459(8%) met ARDS criteria • 332(69%) were admitted as intubated or required immediate intubation • 147(31%) were eligible for study participation and received NIMV • 69 primary ARDS • 78 secondary ARDS
<31% of patients with ARDS are treated with NPPV. • NIMV was succesful in avoiding intubation in 79 (%54) patients. • Avoidance of intubation was associated with a lower insidence of septic complications and increased ICU survival. • SAPSII>34 and a PaO2/FiO2<175 after 1 hr of NIMV were independently associated with the need for endotracheal intubation.
Changes in P/F over time in patients avoided or required intubation 35% 48%
Timing to endotracheal intubation. 70% of NIMV failures were intubated within 48 hrs of initiating NIMV
Risk Factors for NIMV Failureobservational cohort study • 54 patients with ARDS • 38(70.3%) failed, among them all 19 patients with shock • In logistic regression restricted to patients without shock • Metabolic acidosis (OR:1.27, 95%CI:1.03-0.07 per U of BD) • Severe hypoxemia(OR:1.03, 95%CI:1.01-0.05, per U decrease in p/f) Rana S et al, CC 2006;10(3)R79
AIM • To evaluate the effects of various NIMV settings on • Dyspnea • respiratory mechanics • Work of breathing • Respiratory drive • arterial blood gases in patients with ALI
Both PSV settings reduced neuromuscular drive, unloaded the inspiratory muscles, and improved dyspnea • CPAP used alone was unable to reduce inspiratory effort • A PEEP level of 10 cmH2O improved oxygenation compared with initial/final baseline and with PEEP 5 cmH2O • The geatest improvement in dyspnea was obtained with the highest level of PSV
Prone Position • Proning improves oxygenation in 70% of ARDS patients.
PRONE POSITION • Effect of prone position in ARDS • Reduction in shunt • Perfusion is preferentially directed to dorsal lung regions • The gravitational pleural pressure gradient is more uniform • Pleural pressure is reduced in dependent regions • The regional ventilation/perfusion ratio is more uniform and better matched • Improved airway drainage • Improved lymphatic drainage
Randomized controlled trials evaluating prone positioning in ARDS 1- N Eng J Med 2001;345:568-573 2- JAMA 2004;292:2379-2387 3- Am J Respir Crit Care Med 2006;173:1233-1239
Effectes of the prone position on ventilator induced lung injury • Authors measured lung stress as the transpulmonary plateau pressure and lung strain as tidal volume/EELV ratio and found both of them were reduced with the prone position. • The probabbility of VALI can be reduced by the prone position • Mentzelopoulos SD, et al Eur Respir J 2005; 25:534-544
Despite leading to short-term improvements in oxygenetation, prone positioning during MV has failed to improve mortality rates in multiple randomized controlled trials and can not be recommended for the broad population of patients requiring MV due to ARDS. However for those patients who has severe persistent hypoxemia PP may be considered as a rescue therapy.
FLUID MANAGEMENT • Pulmonary edema, even when noncardiogenic in origin, increases with a rise in hydrostatic pressures. • A modest decrease in pulmonary vascular pressure could reduce the quantitiy of pulmonary edema in experimental studies. • Increased EVLW has been associated with poor outcome in ARDS patients. • Balancing the risks of increased edema vs those of decrease vital organ perfusion with a lower intravascular pressure has remained difficult.
NHLBI FACTT Fluid And Catheter Treatment Trial. N Eng J Med 2006; 354:2564-75 • Utility of catheterization with a CVC vs PAC • Liberal fluid management vs conservative fluid management
Mortality Rate • PAC group 27.4%; CVC group, 26.3; p=0.69; 95% CI for difference -4.4 to 6.6%) • Conservative fluid management arms • Had significantly more ventilator free days • More significant improvements in pulmonary physiology • PEEP, Pplat, PaO2/FiO2, oxygenation index, lung injury score • More ICU free days • 2.9% reduction in the 60-day mortality rate(p:0.30) • No difference in incidence or prevalance of shock or RRT
SURFACTANT THERAPY Spragg RG, et al. N Eng J Med 2004; 351:890
INHALED NO • Selective pulmonary vasodilation and improvement ventilation-perfusion mismatch
Pharmacotherapies investigated as possible treatment for ALI/ARDS
CONCLUSION • 30% of ARDS patients may benefited from NIMV • Conservative fluid management strategy may increase ventilator-free days, CVC or PAC does not influence outcome • Prone position may be useful in as rescue therapy in a patient with severe hypoxemia but does not improve survival • Corticosteroids, surfactant and NO are ineffective in improving outcomes.