Prone Positioning in ARDS By Dr Muhammad Akram Khan Qaim KHani

PRONE POSITIONINGPRONE POSITIONING
IN ARDSIN ARDS
BYBY
DR. MUHAMMAD AKRAMDR. MUHAMMAD AKRAM
INTENSIVE CARE UNITINTENSIVE CARE UNIT
MATERNITY AND CHILDREN HOSPITALMATERNITY AND CHILDREN HOSPITAL
MAUSADIA JEDDAHMAUSADIA JEDDAH

Definition of ARDSDefinition of ARDS
 American – European Consensus Conference in 1993American – European Consensus Conference in 1993
defined ARDS as:-defined ARDS as:-
 Clinical syndrome requiring the presence of :-Clinical syndrome requiring the presence of :-
 severe oxygenation abnormality with PaO2/FiO2severe oxygenation abnormality with PaO2/FiO2
<200 torr<200 torr
 Diffuse bilateral pulmonary infiltrates on chestDiffuse bilateral pulmonary infiltrates on chest
radiograph, involving 03or 04 quadrantsradiograph, involving 03or 04 quadrants
 Pulmonary Capillary Wedge Pressure <18mmHgPulmonary Capillary Wedge Pressure <18mmHg
 Absence of clinical elevation of left sided fillingAbsence of clinical elevation of left sided filling
pressure.pressure.
 Synonymous term ALI ( Acute Lung Injury) meets theSynonymous term ALI ( Acute Lung Injury) meets the
same criteria , except the PaO2/FiO2 ratio of <300same criteria , except the PaO2/FiO2 ratio of <300

WHAT IS PRONE POSITIONING?WHAT IS PRONE POSITIONING?

MECHANISMS OF ACTIONMECHANISMS OF ACTION

EFFECTS ON FRCEFFECTS ON FRC
 The volume of gas remaining in the lungs after a normalThe volume of gas remaining in the lungs after a normal
exhalationexhalation
 In the supine position, functional residual capacity (FRC)In the supine position, functional residual capacity (FRC)
decreases due to compression of the lungs by the diaphragmdecreases due to compression of the lungs by the diaphragm
due to intra-abdominal pressure.due to intra-abdominal pressure.
 In the prone position particularly with the abdomen unsupported,In the prone position particularly with the abdomen unsupported,
abdominal weight shifts the diaphragm caudally, increasing theabdominal weight shifts the diaphragm caudally, increasing the
FRCFRC
 . In normal and obese anaesthetized and paralyzed patients. In normal and obese anaesthetized and paralyzed patients
prone positioning resulted in improved FRC and oxygenation.prone positioning resulted in improved FRC and oxygenation.
Increased FRC results in end expiratory alveolar recruitmentIncreased FRC results in end expiratory alveolar recruitment


EFFECTS ON PERFUSIONEFFECTS ON PERFUSION
 In the supine position there is a perfusion gradient from the dependentIn the supine position there is a perfusion gradient from the dependent
dorsal lung to the non-dependent ventral lungdorsal lung to the non-dependent ventral lung
 SPECT imaging of intravenously injected radiolabelled albuminSPECT imaging of intravenously injected radiolabelled albumin
demonstrated maintenance of dorsal predominant flow in the pronedemonstrated maintenance of dorsal predominant flow in the prone
position .position .
 Regional perfusion is always preferentially directed to dorsal lungRegional perfusion is always preferentially directed to dorsal lung
regions regardless of whether these regions are in the dependent orregions regardless of whether these regions are in the dependent or
nondependent position. This non-gravitational blood flow hasnondependent position. This non-gravitational blood flow has
implications for understanding the mechanism by which the proneimplications for understanding the mechanism by which the prone
position results in improved gas exchange.position results in improved gas exchange.
 If the dorsal regions always receive preferential perfusion the only wayIf the dorsal regions always receive preferential perfusion the only way
intra-pulmonary shunt can be reduced is as a result improved regionalintra-pulmonary shunt can be reduced is as a result improved regional
ventilation of underventilated or atelectatic dorsal regions in the proneventilation of underventilated or atelectatic dorsal regions in the prone
position which are perfused but not well ventilated when supine.position which are perfused but not well ventilated when supine.

 EFFECTS ON VENTILATIONEFFECTS ON VENTILATION
 Regional lung ventilation is determined by the pleural pressure gradientRegional lung ventilation is determined by the pleural pressure gradient
 In normal subjects in the supine position the non-dependent ventralIn normal subjects in the supine position the non-dependent ventral
lung has a more negative pleural pressure compared to the dependentlung has a more negative pleural pressure compared to the dependent
dorsal lung region and this determines regional ventilation with thedorsal lung region and this determines regional ventilation with the
ventral lung receiving more ventilation.ventral lung receiving more ventilation.
 In the setting of acute lung injury in the supine position the pleuralIn the setting of acute lung injury in the supine position the pleural
pressure of the non-dependent ventral lung remains negative, howeverpressure of the non-dependent ventral lung remains negative, however
the pleural pressure of the dependent dorsal lung region becomesthe pleural pressure of the dependent dorsal lung region becomes
positive. This large pleural pressure gradient results in overdistension ofpositive. This large pleural pressure gradient results in overdistension of
the ventral lung and reduced ventilation to the dorsal lung.the ventral lung and reduced ventilation to the dorsal lung.
 In addition the positive pleural pressure in the dorsal lung region tendsIn addition the positive pleural pressure in the dorsal lung region tends
to promote atelectasis further reducing ventilation in this regionto promote atelectasis further reducing ventilation in this region
 . In the prone position, the ventral - dorsal pleural pressure gradient is. In the prone position, the ventral - dorsal pleural pressure gradient is
markedly reducedmarkedly reduced
 The prone position eliminates the compression of the lungs by the heartThe prone position eliminates the compression of the lungs by the heart

 MISCELLANEOUS EFFECTSMISCELLANEOUS EFFECTS
 It is interesting to note that prone position has been shown to induceIt is interesting to note that prone position has been shown to induce
redistribution of lung density indicating more uniform regional ventilation.redistribution of lung density indicating more uniform regional ventilation.
This suggests additional mechanisms may be important in improvingThis suggests additional mechanisms may be important in improving
gas exchange.gas exchange.
 Improved mobilization of secretions or redistribution of extravascularImproved mobilization of secretions or redistribution of extravascular
lung water. The significance of alteration in extravascular lung waterlung water. The significance of alteration in extravascular lung water
(EVLW) in ARDS remains to be defined.(EVLW) in ARDS remains to be defined.

12/27/15 10
CLINICAL EFFECTSCLINICAL EFFECTS
 EFFECT ON OXYGENATIONEFFECT ON OXYGENATION
 Prone positioning was first reported to improve oxygenation in acuteProne positioning was first reported to improve oxygenation in acute
respiratory failure in two small studies in the 1970srespiratory failure in two small studies in the 1970s
 EFFECT ON RESPIRATORY MECHANICSEFFECT ON RESPIRATORY MECHANICS
 Associated with an initial decrease in respiratory system complianceAssociated with an initial decrease in respiratory system compliance
which subsequently improves during the prone period and increaseswhich subsequently improves during the prone period and increases
when returned to supine.when returned to supine.
 The initial reduction when the patient is turned prone is probably due toThe initial reduction when the patient is turned prone is probably due to
a decrease in chest wall compliance. It is suggested that maintaininga decrease in chest wall compliance. It is suggested that maintaining
support of the abdomen might have avoided the initial increase insupport of the abdomen might have avoided the initial increase in
respiratory system compliancerespiratory system compliance
 In contrast, the subsequent improvement seems to relate to theIn contrast, the subsequent improvement seems to relate to the
increase in lung compliance.increase in lung compliance.
 EFFECT ON CO2 CLEARANCEEFFECT ON CO2 CLEARANCE
 Prolonged prone ventilation is associated with improvement in CO2Prolonged prone ventilation is associated with improvement in CO2
clearance which is related to improvement in alveolar ventilation in well-clearance which is related to improvement in alveolar ventilation in well-
perfused areas.perfused areas.

PRONE POSITIONING FOR ARDSPRONE POSITIONING FOR ARDS

Treatment of ARDS is largely supportiveTreatment of ARDS is largely supportive
 Prone positioning has been suggested since 1974 (9) as a ventilatoryProne positioning has been suggested since 1974 (9) as a ventilatory
strategy to improve oxygenation and pulmonary mechanics in patientsstrategy to improve oxygenation and pulmonary mechanics in patients
with ALI and ARDS.with ALI and ARDS.
 INDICATIONS:INDICATIONS:
 Pulmonary dysfunction despite escalating mechanical ventilatoryPulmonary dysfunction despite escalating mechanical ventilatory
supportsupport
 GOALS OF VENTILATION:GOALS OF VENTILATION:
 SaO2 >92%SaO2 >92%
 PaO2/FiO2 ≥200PaO2/FiO2 ≥200
 pH 7.25 – 7.40pH 7.25 – 7.40
 Pplat <35 cm H2OPplat <35 cm H2O

 Criteria for Inclusion:Criteria for Inclusion:
 CXR with diffuse bilateral infiltrates consistent withCXR with diffuse bilateral infiltrates consistent with
ALI or ARDSALI or ARDS
 Mechanical ventilationMechanical ventilation
 FiO2 ≥ 0.6 for 48 hoursFiO2 ≥ 0.6 for 48 hours
 PEEP ≥ 15 cm for 48 hours (includes PCIRV, auto PEEP)PEEP ≥ 15 cm for 48 hours (includes PCIRV, auto PEEP)
 Increasing respiratory dysfunction as evidenced by:Increasing respiratory dysfunction as evidenced by:
 PaO2/FiO2 < 200PaO2/FiO2 < 200

 Exclusion Criteria:Exclusion Criteria:
 Closed head injury with ICHClosed head injury with ICH
 Unstable orthopedic fractureUnstable orthopedic fracture
 Spinal cord injurySpinal cord injury
 Hemodynamic instabilityHemodynamic instability
 Active intraabdominal processActive intraabdominal process
 PregnancyPregnancy

TECHNIQUE OF POSITIONINGTECHNIQUE OF POSITIONING
 There is no standardized method for turning.There is no standardized method for turning.
 Most studies describe a log roll in two steps with the variable use of a glideMost studies describe a log roll in two steps with the variable use of a glide
sheet under the patient.sheet under the patient.
 In the first step the patient is moved to one edge of the bed and then movedIn the first step the patient is moved to one edge of the bed and then moved
into the lateral position to face the other edge of the bed.into the lateral position to face the other edge of the bed.
 In the second step the patient is placed in the prone position.In the second step the patient is placed in the prone position.
 One study used a portable support frame that acts as an anchor for theOne study used a portable support frame that acts as an anchor for the
body during the turn and then serves as a cushion device to maintain thebody during the turn and then serves as a cushion device to maintain the
abdomen free of restriction in the prone position.abdomen free of restriction in the prone position.
 In the majority of studies 5 persons including an experienced physician whoIn the majority of studies 5 persons including an experienced physician who
can re-intubate the patient if necessary were used to turn the patient.can re-intubate the patient if necessary were used to turn the patient.
 In one study 3 members of nursing staff turned the patient. In this studyIn one study 3 members of nursing staff turned the patient. In this study
there was only one unplanned extubation in 148 turning prone cyclesthere was only one unplanned extubation in 148 turning prone cycles
(supine – prone – supine) which was treated immediately with no deleterious(supine – prone – supine) which was treated immediately with no deleterious
effect.effect.
 Each person has a defined role, with one person having responsibility forEach person has a defined role, with one person having responsibility for
the airway.the airway.
 Prior to turning any patient prone proper placement and fixation of thePrior to turning any patient prone proper placement and fixation of the
endotracheal tube must be confirmed.endotracheal tube must be confirmed.

 Vascular lines must also be monitored during turning to avoidVascular lines must also be monitored during turning to avoid
displacement.displacement.
 Following repositioning, the endotracheal tube and all cathetersFollowing repositioning, the endotracheal tube and all catheters
should be surveyed to assure that no displacement has occurred.should be surveyed to assure that no displacement has occurred.
 The importance of avoiding non-physiological movement of theThe importance of avoiding non-physiological movement of the
arms during turningarms during turning
 the importance of protecting pressure areas including areasthe importance of protecting pressure areas including areas
overlying all tubes and Foley and intravascular catheters andoverlying all tubes and Foley and intravascular catheters and
avoiding ocular injury was emphasized.avoiding ocular injury was emphasized.
 It is emphasized that staff involved in the management of patients inIt is emphasized that staff involved in the management of patients in
the prone position should be aware of the procedure to rapidly turnthe prone position should be aware of the procedure to rapidly turn
patients with severe cardiopulmonary instability, as CPR requires apatients with severe cardiopulmonary instability, as CPR requires a
return to the supine position.return to the supine position.

 Reposition ECG leads to patient’s back.Reposition ECG leads to patient’s back.
 Anticipate the need for frequent ETT suctioning.Anticipate the need for frequent ETT suctioning.
 Obtain ABG 20 minutes after repositioning.Obtain ABG 20 minutes after repositioning.
 Duration of prone positioning is dependent upon patient’sDuration of prone positioning is dependent upon patient’s
hemodynamic statushemodynamic status

PREDICTION OF RESPONSEPREDICTION OF RESPONSE
 Methods of predicting a positive response to prone positioning areMethods of predicting a positive response to prone positioning are
not well studied.not well studied.
 Langer was the first to classify patient as “responders” and “non-Langer was the first to classify patient as “responders” and “non-
responders” according to the presence or absence of an increase inresponders” according to the presence or absence of an increase in
paO2 of more than 10mmHg after 30 minutes.paO2 of more than 10mmHg after 30 minutes.
 Subsequently the definition of response varied widely. Change hasSubsequently the definition of response varied widely. Change has
been measured both in absolute change in paO2 and paO2 / FiO2been measured both in absolute change in paO2 and paO2 / FiO2
ratio as well as percentage change in the paO2 / FiO2 ratio.ratio as well as percentage change in the paO2 / FiO2 ratio.
 Both the magnitude of change and time period over which theBoth the magnitude of change and time period over which the
change is measured have varied widely.change is measured have varied widely.
 Several studies divide the groups into responders and non-Several studies divide the groups into responders and non-
responders but do not actually define the criteria on which this isresponders but do not actually define the criteria on which this is
basedbased
 Though available research makes no specific recommendations, 6Though available research makes no specific recommendations, 6
or more hours a day, for as long as 10 days, appears typical inor more hours a day, for as long as 10 days, appears typical in
clinical studies and reported practice.clinical studies and reported practice.

Prone Positioning in ARDS By Dr Muhammad Akram Khan Qaim KHani

Prone Positioning in ARDS By Dr Muhammad Akram Khan Qaim KHani

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