Hemodynamic Stabilisation In Septic Shock
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Transcript of Hemodynamic Stabilisation In Septic Shock
Hemodynamic Stabilisation in Septic shock
Dr. T.R.Chandrashekar
Intensivist K.R. Hospital
Bangalore
• Shock is defined as a life-threatening, generalized maldistribution of blood flow resulting in failure to deliver and/or utilize adequate amounts of oxygen, leading to tissue dysoxia.
• Hypotension [SBP < 90 mmHg, SBP decrease of 40 mmHg from baseline, or mean arterial pressure (MAP) < 65 mmHg], while commonly present, should not be required to define shock.
• Shock requires evidence of inadequate tissue perfusion on physical examination.
Shock
Septic shock
• The definition underscore a few points
• 1) Blood flow at a adequate pressure (MAP)> 65mmHg
• Shock can still occur with a normal perfusion.
• Delivery and utilisation of O2 at cellular level-abnormalities are the hall mark of septic shock.
Septic shock
MacrocirculationPerfusion with adequate oxygen
Microcirculation Improper delivery and utilisation
Mitochondrial dysfuction
Microcirculatory and Mitochondrial Distress syndrome
(MMDS)MMDS = sepsis +genes+ therapy + time
Hostgenetic background
co-morbidity
HIT infectiontraumaburnsetc.
timetherapy
MMDS
Figure 2
Adequate perfusion pressure
MAP>=65mmHg
Adequate oxygen delivery
CO x Hb x SPO2 x 1.34 + .003 x PaO2
Optimisation of Macrocirculation • Assessment • Clinical Hypotension Tachycardia Altered mental status Delayed capillary refill Decreased urine output Cool skin Cold extremities
• Hemodynamic parameters
• Organ perfusion
• Goals • HEMODYNAMCS
• CVP = 8–12 mm Hg
• MAP > = 65 mm Hg
• CI >=2.5- 3 L/min/m2
• O2 DELIVERY• Arterial Hgb SpO2 > 93%
• ScVO2 > =70 mm Hg
• Blood Lactate Conc < 2 mM/L
• Hematocrit >=30%
• ORGAN PERFUSION• CNS - improved sensorium• Skin - warm, well perfused• Renal - Urine output >=0.5ml/kg/hr
Hemodynamic Truths
• Tachycardia is never a good thing
• Hypotension is always pathological
• There is no normal cardiac output
• CVP is only elevated in disease
• Peripheral edema is of cosmetic concern
Volume Vesseltone
Heart function
If shock is prolonged, mechanisms of shock are combined
Physiologic Classification of Physiologic Classification of Acute Circulatory InsufficiencyAcute Circulatory Insufficiency
Fluids / blood Vasopressors Inotropes
The questionThe question “Will my patient respond “Will my patient respond to fluids?”to fluids?” cannot be accurately cannot be accurately
answered by any ‘preload’ parameteranswered by any ‘preload’ parameterPrinciples of Volume challenge
To test Starling’s law the fluid needs to be given quickly – the faster it is given the less that is needed
It makes no sense to test “preload” responses over long periods of time (eg Kumar et al 2004)
The type of fluid is not critical if given quickly enough
There needs to be a change in CVP to know that Starling’s Law has been tested
PRELOAD assessment-Volume • To look at CVP/ PAOP• Always CVP is in relation to CO
Volume responsive
Volume unresponsive
Add dopamine or dobutamine
Volume
SV
Decreased contractility
Right atrial volume
–The actual value of the CVP is determined by the interaction of Cardiac function and return function
return function
cardiac function
PRELOAD assessment
• Attempts to assess EDV through surrogate measures– CVP, Ppao, LV end-diastolic area, RV EDV,
intrathoracic blood volume
5. A fluid challenge and flow response remain the gold standard for assessing fluid responsiveness
6. The functional range of CVP/Pra is small so that technical factors are important
Importance of leveling Transmural pressure Position on waveform
CO
Preload
Fluid Responsiveness is a dynamic parameter Fluid Responsiveness is a dynamic parameter that reflects the degree by which the CO that reflects the degree by which the CO
responds to changes in preloadresponds to changes in preload
““Will my patient respond to fluids?”Will my patient respond to fluids?”
Dynamic (functional) parameters
SPV / dDown, PPV, SVV, RSVT, SPV / dDown, PPV, SVV, RSVT, OthersOthers
• ‘‘RULE OF THUMB’RULE OF THUMB’
• (in the absence of any confounding factors(in the absence of any confounding factors))
• If If SPV > 10 mmHg (or 10%), SVV>10%, PPV>13% --- SPV > 10 mmHg (or 10%), SVV>10%, PPV>13% --- probable significant volume responsiveness (may indeed probable significant volume responsiveness (may indeed signify hypovolemia!)signify hypovolemia!)
• Spontaneously breathing patientsSpontaneously breathing patients • Passive leg raising testPassive leg raising test
MV PATIENTS
• Fluid resuscitation may consist of natural or artificial colloids or crystalloids• No evidenced-based support for one type of
fluid over another• Crystalloids have a much larger volume of
distribution compared to colloids• Crystalloid resuscitation requires more fluid to
achieve the same endpoints as colloid• Crystalloids result in more edema
Fluid Therapy: Choice of Fluid
Grade C
Dellinger, et. al. Crit Care Med 2004, 32: 858-873.
• Fluid challenge in patients with suspected hypovolemia may be given• 500 - 1000 mL of crystalloids over 30 mins• 300 - 500 mL of colloids over 30 mins• Repeat based on response and tolerance• Input is typically greater than output due to
venodilation and capillary leak• Most patients require continuing aggressive fluid
resuscitation during the first 24 hours of management
Fluid Therapy: Fluid Challenge
Grade E
Dellinger, et. al. Crit Care Med 2004, 32: 858-873.
SHOCK
MAP < 65mmHgOliguria (<0.5ml/Kg/hour)
Clinical signs of tissue hypoperfusion
1) Clinical approach
-HR/BP-Peripheral perfusion-Impact of volume loading-Urine output
2) CVP/SvcO2
3) Echocardiographyshould preceed any CO monitoring
Predominant RVF or global F
PAC catheter
Predominant LVFany CO monitoring
First step
Second step
Third step
Fourth step
Mixed/central venous O2 saturationMixed/central venous O2 saturation
o marker of global supply/demand balanceo falls in low output states e.g. heart failureo prognosticator of outcome, failure to wean…o elevated in resuscitated sepsis
o microvascular shunting??o decreased cellular utilisation??
o mixed venous vs central venous differenceso one landmark ScvO2-targetted study
(Rivers)
75%
Factors that influence mixed and central venous Factors that influence mixed and central venous SOSO22
VO2 DO2 DO2 VO2 Stress
Pain
Hyperthermia
Shivering
PaO2
Hb
Cardiac output
PaO2
Hb
Cardiac output
Hypothermia
Anesthesia
_ +
Mixed/central SvO2Mixed/central SvO2
o PA catheter use decline .. ∆ reliance on ScvO2
o Useful in global low output stateso Limited in established sepsis (other than identification of low values)
SvO2 closely correlates with ScvO2SvO2 closely correlates with ScvO2
The major problems with the interpretation of ScvO2
• Like the CO, a low SvO2 tells you that something is wrong, but not what is wrong and what should be done about it (fluids? inotropes?).
• When the SvO2 is normal or high -one cannot assume that all is well (e.g., CO normal) since in septic patients the ScvO2 may be elevated due to an abnormally low O2 extraction.
InsertCVP/SvcO2
SvO2 >70% SvO2 <70%
Sepsis?
Repeat Fluid challenge250ml/ 5mins
Haemodynamic improvement ?
Consider global/right ventricular failure
Echocardiography that preceeds cardiac output monitoring
Yes
Continue until normal values
obtained
No
Vasopressors
Hypovolaemic/Haemorrhagic/
cause?
No response
Continue until normal values obtained
Haemodynamicimprovement
Repeat fluid challenge(250ml/5mins)or transfusion if necessary.
Echocardiography that preceeds CO monitoring
CVP N or lowCVP high CVP low
How to differentiate between Contractility vs Vasomotor tone
• Echocardiography • Cardiac output monitoring
INTERPRETATION OF CARDIAC OUTPUT
Do we have a problem ?
Arterial hypotension Tachycardia Oliguria
Increase incardiac output
FLUIDS ?
Do we need to measurecardiac output ?
DOBUTAMINE ?
Why/when would I want to measure CO or SV in shock?
• Failure hemodynamic management based on clinical signs and CVP-ScvO2; this should always direct to echocardiography
• Echocardiography should, ideally, always preceed CO monitoring
• CO monitoring shoud be a PAC catheter in case of RV dysfunction while any CO monitoring, less invasive than PAC, should be favored for LV dysfunction
The way I do
• After adequate fluid resusciation
• Start with nor adrenaline then add dobutamine- looking at contractility and SVR
• If MAP <65 mmHg
• Add adrenaline or contemplate
• Vasopressin or phenylephrine
• Initiate vasopressor therapy if appropriate fluid challenge fails to restore adequate blood pressure and organ perfusion
• Vasopressor therapy should also be used transiently in the face of life-threatening hypotension, even when fluid challenge is in progress
• Either norepinephrine or dopamine are first line agents to correct hypotension in septic shock
• Norepinephrine is more potent than dopamine and may be more effective at reversing hypotension in septic shock patients
• Dopamine may be particularly useful in patients with compromised systolic function but causes more tachycardia and may be more arrhythmogenic
Vasopressors Grade E
Grade D
• Low dose dopamine should not be used for renal protection in severe sepsis
• An arterial catheter -Vasopressors Arterial catheters provide more accurate and
reproducible measurement of arterial pressure Vasopressin may be considered in refractory shock
patients that are refractory to fluid resuscitation and high dose vasopressors
• Infusion rate of 0.01-0.04 units/min in adults• May decrease stroke volume
Vasopressors (cont)Grade B
Grade E
Grade E
• In patients with low cardiac output despite adequate fluid resuscitation, dobutamine may be used to increase cardiac output • Should be combined with vasopressor therapy in the
presence of hypotension
• It is not recommended to increase cardiac index to target an arbitrarily predefined elevated level • Patients with severe sepsis failed to benefit from
increasing oxygen delivery to supranormal levels by use of dobutamine
Inotropic TherapyGrade E
Grade A
Hemodynamic Patterns with Prognostic Value
• A lower heart rate at the onset of disease is predictive of survival.
• Normalization within 24 hours of either tachycardia or elevated cardiac index is associated with survival. Persistence of hyperdynamic state increases likelihood of death.
• A low ejection fraction and ventricular dilatation are also associated with survival. This perhaps reflects Frank-Starling compensation of sepsis induced myocardial depression.
•Even with the ‘best’ parameters it is not always easy to make the right decision.………
“…Our understanding of hemodynamic mechanisms (in distributive shock) depends not so much on the total volume of blood that flows past the aortic valve or the cardiac output as on the amount of blood delivered to the exchange sites. Even though cardiac output may be substantial, if that blood flow does not arrive at the exchange sites, the ultimate metabolic detriment is no different from low cardiac output without shunt flow.”
Weil MH, Shubin H (1971) Adv Exp Med Biol 23:13-23.
Why the microcirculation is important in shock.
1. It is where oxygen exchange takes place.
2. It plays a central role in the immune system.
3. During sepsis and shock it the first to go and last to recover.
4. Rescue of the microcirculation = resuscitation end-point.
Shunting model of sepsisShunting model of sepsis
O2
lactateCO2
vvaa
Implication : that active recruitment of the microcirculationis an important component of resuscitation.
Ince C & Sinaasappel M (1999) Crit Care Med 27:1369-1377
Spronk P, Zandstra D, Ince C (2004) Critical Care 8:462-468
Sepsis is a disease of the microcirculation
Mitochondrial Dysfunction in Cell Injury
Increased cytosolic Ca2+, oxidative stress, lipid peroxidation
Mitochondrial PermeabilityTransition
Cytochrome c and other pro-apoptotic proteins
ApoptosisRobbins & Cotran Robbins & Cotran Pathologic Basis of Disease: 2005Pathologic Basis of Disease: 2005
Functional and Morphologic Consequences of Decreased ATP During Cell Injury
Ischemia
Oxidative PhosphorylationATP
Na pump
Influx of Ca2+
H20, and Na+
Efflux of K+
ER swellingCell swellingBlebs
Clumpingchromatin
Anaerobic glycolysis
GlycogenpH
Lipid deposition
Detachment of ribosomes
Protein synthesis
Energy failure
BE - Lactate
Pump failure or
mitochondrial dysfunction
Hemodynamic failure
Pump failure
Volume test
VO2 Lactate
Mitochondrial dysfunction
VO2 Lactate
Dobutamine test
VO2 Lactate
VO2 Lactate
Hemodynamic and mitochondrial failure
Microcirculation assessment
• Tissue perfusion• Gastric tonometry
Orthogonal polarizationspectral (OPS) imaging
Capillary flow in sepsis
Microcirculation Recruitment Manoeuvres Ince C (2005) Critical Care 9:S13-S19
Correct pathological flow heterogeneity, microcirculatory shunting and restore autoregulatory dysfunction by control of inflammation, vascular function and coagulation.
Avontuur (1997) Cardiovas Res 35:368-376.
Siegmund M (2005) Inten Care Med 31:985-992.
Open the microcirculation and keep it open by support of the pump, fluids, vasodilators and restricted use of vasopressor agents. :
Boerma (2005) Acta Anaesthesiol Scand. 49(9):1387-90. Spronk (2001) The Lancet 360:1395-1396
Siegemund (2006) Intensive Care Med
Sublingual OPS imaging in a patient with septic shock after pressure guided volume resuscitation.
the same patient after subsequent nitroglycerin 0.5 mg ivbolus
Nitroglycerin promotes microvascular Nitroglycerin promotes microvascular recruitment in septic and cardiogenic recruitment in septic and cardiogenic
shock patientsshock patients
Spronk, Ince, Gardien, Mathura, Oudemans-van Straaten, Zandstra DF. (2002) The Lancet 360:1395-1396.
Conclusions
1) Distributive shock has a bad prognosis with difficult to define hemodynamics end-points.
2) It causes a distributive defect at the apillary level of the microcirculation causing functional shunting of weak microcirculatory units.
3) It is the reason why distributive shock cannot be adeqautely monitored by systemic hemodynamic parameters.
4) OPS/SDF en tissue capnography provide an integrative evaluation of the functional state of the microcirculation.
5) Microcirculatory Recruitment Maneuvres are affective in correcting distributive shock
Take home thoughts
• Time is important-EGDT Energy failure may be due to primitive
hemodynamic inadequacy and/or mitochondrial dysfunction
• Prolonged energy failure leads to irreversible mitochondrial dysfunction (necrosis - apoptosis
• Once MMDS starts shock becomes irreversible• First optimise macrocirculation
Some “Pretty Good” Cardiovascular Management Goals
• Fluid resuscitation to keep a CI > 2.5 l/min/m2 with a Ppao < 20 mm Hg
• Add inotropic support if unable to sustain CI within this Ppao limit
• Vasopressors to maintain a mean arterial pressure > 65 mm Hg
• If measures of organ perfusion available (urine output, PCO2, tissue blood flow, Serum lactate, base deficit ) use them to guide response to therapy.
• Trends may be more important than absolute values