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HEMODYNAMIC MONITORING
Part 2Dr.Gagan BrarMD,IDCCMEDIC
Monitoring of physiologic variables comprises an integral part of the care of the critically ill patient
Assists the intensivist in both diagnostic and treatment strategies.
Debate regarding the usefulness and safety of invasive hemodynamic monitoring in the intensive care unit (icu).
Several studies have shown improved outcomes from hemodynamic monitoring in high-risk surgical patients, but there is conflicting evidence as to benefits in the critically ill medical patient
3
Standard Monitoring
Monitoring
Respiration Rate
NIBP
ECG
Temperature
Urine Production
Oxygen Saturation
Blood Circulation(clinical assessment)
• will fluid increase perfusion to end organs, or will it worsen pulmonary or systemic edema?
• oxygen delivery• • Organ perfusion
TOO LESS
• Too much interstitial fluid• Too much lung water• Poor outcomes
TOO MUC
H
CVP = 8 – 12 mm Hg
CONTINUE AS LONG AS THERE IS HAEMODYNAMIC IMPROVEMENT
Does it improve organ perfusion?
By how much?
For how long?
LIB CON-1000
0
1000
2000
3000
4000
5000
6000
7000
6992
-136
Series1
Comparison of two fluid-management strategies in acute lung injury. N Engl J Med. 2006 Jun 15;354(24):2564-75.
FACTT trial – fluid conservative (-136) Vs liberal (6992 ml) in the first 7 days
FACTT – VENTILATOR FREE DAYS
Comparison of two fluid-management strategies in acute lung injury. N Engl J Med. 2006 Jun 15;354(24):2564-75.
CUMULATIVE FLUID BALANCEWAS MOST LETHAL!!
Sepsis in European intensive care units: results of the SOAP study. Crit Care Med. 2006 Feb;34(2):344-53.
In a multicentre European observational study, a CUMULATIVE FLUID balance at 72 hours was among the strongest predictors of death. 24 European countries, 198 ICUs, 3147 adult patients. Cumulative fluid balance in the first 72 hrs
RRT Fluid overload 59.2%
RRT No fluid overload 31.4%
Fluid overload is associated with an increased risk for 90-day mortality in critically ill patients with renal replacement therapy: data from the prospective FINNAKI study. Critical Care 2012, 16:R197
Prospective observational study of 296 RRT treated patients. Fluid overload – gain in more than 10% body weight at time of RRT. Fluid overload led to increased 90 day mortality; odds ratio: 2.6
<0 0 to 5% 5 to 10% 10 to 15% >15%0
10
20
30
40
50
60
70
Series1
Fluid overload is associated with an increased risk for 90-day mortality in critically ill patients with renal replacement therapy: data from the prospective FINNAKI study. Critical Care 2012, 16:R197
Pressure that dilates the ventricle = intraventricular – pleural pressure (what we can measure at best is intra-cavity pressure)
• Static measurements have failed as a meaningful endpoint for fluid resuscitation
• Rapid fluid bolus is a reasonable diagnostic and potentially therapeutic option
• Has the potential to cause harm • May delay institution of appropriate therapy
• . GOALS SHOULD BE BASED IN SCIENCE AND SUPPORTED BY EVIDENCE.
CARDIAC OUTPUT
cardiac output • first measured by the German physician and physiologist Adolf Fick 1870 using
an oxygen uptake method.
The Fick method was later modified in 1897 by Stewart to use a continuous saline infusion and then in 1928 by Hamilton to use abolus injection of dye technique .
Monitoring • Invasive• pulmonary artery catheter
Non-invasive• Bio impedence cardiac output monitoring• Partial carbon dioxide re breathing cardiac output monitoring
Minimally invasive• oesophageal Doppler
• Transpulmonary thermodilution and pulse contour analysis PiCCO LiDCO• Pulse contour analysis, FlowTrac , PRAM• Ultrasound dilution, COstatus
Pulse Index Continuous Cardiac Output(PiCCO)
PiCCO Technology is a combination of transpulmonary thermodilution and pulse contour analysis
Principles of Measurement
Left HeartRight Heart
Pulmonary CirculationLungs
Body CirculationPULSIOCATHPULSIOCATH
CVC
PULSIOCATH arterial thermodilution catheter
central venous bolus injection
Introduction to the PiCCO-Technology – Function
central venous injection of a cold bolus and detection of the temperature course in a peripheral large artery (femoral, axillary, brachial) through a special thermodilution catheter.
calibrated from the results of the thermodilution measurement and delivers continuous haemodynamic parameters in contrast to intermittent thermodilution.
Bolus injection
concentration changes over time(Thermodilution curve)
After central venous injection the cold bolus sequentially passes through the various intrathoracic compartments
The temperature change over time is registered by a sensor at the tip of the arterial catheter
Introduction to the PiCCO-Technology – Function
Left heartRight heart Lungs
RA RV LA LVPBV
EVLW
EVLW
Principles of Measurement
The individual cardiac chambers and the lung with the extravascular lung water are mixing chambers in which the cold bolus is distributed
Tb x dt(Tb - Ti) x Vi
x K
Tb
Injection
t
∫ D=COTD a
Tb = Blood temperatureTi = Injectate temperatureVi = Injectate volume∫ ∆ Tb
. dt = Area under the thermodilution curveK = Correction constant, made up of specific weight and specific heat of blood and injectate
The CO is calculated by analysis of the thermodilution curve using the modified Stewart-Hamilton algorithm
Calculation of the Cardiac Output
Various volume parameters can be calculated from the thermodilution curve, which is recorded via the thermodilution catheter (PiCCO catheter).
The area under the thermodilution curve is inversely proportional to the CO.
36,5
37
5 10
Thermodilution curves
Normal CO: 5.5l/min
Introduction to the PiCCO-Technology – Thermodilution
36,5
37
36,5
37
Time
low CO: 1.9l/min
High CO: 19l/min
Time
Time
Temperature
Temperature
Temperature
MTt: Mean Transit time the mean time required for the indicator to reach the detection point
DSt: Down Slope time the exponential downslope time of the thermodilution curve
Recirculation
t
e-1
Tb
From the characteristics of the thermodilution curve it is possible to determine certain time parameters
Extended analysis of the thermodilution curve
Introduction to the PiCCO-Technology – Thermodilution
Injection
In Tb
MTt DSt
Tb = blood temperature; lnTb = logarithmic blood temperature; t = time
time from injection to the point at which the thermodilution curve has fallen to 75% of its maximum. Downslope time in which TD curve falls from 75% of its max to 25% of its maximum.mixing behaviour of the indicator in the largest mixing chamber
Pulmonary Thermal Volume
PTV = Dst x CO
By using the time parameters from the thermodilution curve and the CO ITTV and PTV can be calculated
Calculation of ITTV and PTV
Introduction to the PiCCO-Technology – Thermodilution
Recirculation
t
e-1
Tb
Injection
In Tb
Intrathoracic Thermal Volume
ITTV = MTt x CO
MTt DSt
Intrathoracic Compartments (mixing chambers)
Introduction to the PiCCO-Technology – Function
Pulmonary Thermal Volume (PTV)
Intrathoracic Thermal Volume (ITTV)
Total of mixing chambers
RA RV LA LVPBV
EVLW
EVLW
Largest single mixing chamber
ITTV : all four cardiac chambers, the pulmonary circulation and the extravascular lung water forms the total intrathoracic thermal volume.
The largest single mixing chamber in this system is the pulmonary thermal volume, which consists of the blood volume of the pulmonary circulation and the extravascular lung water.
Pulmonary Thermal Volume (PTV)
Intrathoracic Thermal Volume (ITTV)
Calculation of ITTV and PTV
Einführung in die PiCCO-Technologie – Thermodilution
ITTV = MTt x CO
PTV = Dst x CO
RA RV LA LVPBV
EVLW
EVLW
PTV represents the largest single mixing chamber in the thorax, the pulmonary thermal volume, which consists of the blood volume of the pulmonary circulation (pulmonary blood volume, PBV) and the extravascular lung water (EVLW).
GEDV is the difference between intrathoracic and pulmonary thermal volumes
Global End-diastolic Volume (GEDV)
Volumetric preload parameters – GEDV
RA RV LA LVPBV
EVLW
EVLW
ITTV
GEDV
PTV
Introduction to the PiCCO –Technology – Thermodilution
the total blood volume in all 4 cardiac chambers
that gives information about the filling condition of the heart and thus about cardiac preload.
Volumetric preload parameters – ITBV
Intrathoracic Blood Volume (ITBV)
GEDV
ITBV
PBVRA RV LA LVPBV
EVLW
EVLW
Introduction to the PiCCO –Technology – Thermodilution
ITBV is the total of the Global End-Diastolic Volume and the blood volume in the pulmonary vessels (PBV)
the total blood volume present in the heart and pulmonary circulation
Transpulmonary Thermodilution
The pulse contour analysis is calibrated through the transpulmonary thermodilution and is a beat to beat real time analysis of the arterial pressure curve
Calibration of the Pulse Contour Analysis
Introduction to the PiCCO-Technology – Pulse contour analysis
Injection
Pulse Contour Analysis
T = blood temperature t = timeP = blood pressure
COTPD= SVTD
HR
PCCO = cal • HR •P(t)SVR + C(p) • dP
dt( ) dt
Cardiac Output
Patient- specific calibration factor (determined by thermodilution)
Heart rate Area under the pressure curve
Shape of the pressure curve
Aortic compliance
Systole
Introduction to the PiCCO-Technology – Pulse contour analysis
Parameters of Pulse Contour Analysis
Besides the area under the pressure curve and other factors, calculation of the continuous PiCCO pulse contour cardiac output also involves the aortic compliance measured by thermodilution, which represents an important advantage compared to systems that cannot be calibrated.
SVmax – SVminSVV =
SVmean
SVmax
SVmin
SVmean
The Stroke Volume Variation is the variation in stroke volume over the ventilatory cycle, measured over the previous 30 second period.
Parameters of Pulse Contour Analysis
Introduction to the PiCCO-Technology – Pulse Contour Analysis
Dynamic parameters of volume responsiveness – Stroke Volume Variation
PPmax – PPminPPV =
PPmean
The pulse pressure variation is the variation in pulse pressure over the ventilatory cycle, measured over the previous 30 second period.
Parameters of Pulse Contour Analysis
Introduction to the PiCCO-Technology – Pulse Contour Analysis
Dynamic parameters of volume responsiveness – Pulse Pressure Variation
PPmax
PPmean
PPmin
Contractility is a measure for the performance of the heart muscle
Contractility parameters of PiCCO technology:
- dPmx (maximum rate of the increase in pressure)
- GEF (Global Ejection Fraction)
- CFI (Cardiac Function Index)
Contractility
Introduction to the PiCCO-Technology – Contractility parameters
kg
ITTV
– ITBV
= EVLW
The Extravascular Lung Water is the difference between the intrathoracic thermal volume and the intrathoracic blood volume. It represents the amount of water in the lungs outside the blood vessels.
Calculation of Extravascular Lung Water (EVLW)
Introduction to the PiCCO –Technology – Extravascular Lung Water
Differentiating Lung Oedema
PVPI = Pulmonary Vascular Permeability Index
• is the ratio of Extravascular Lung Water to Pulmonary Blood Volume
• is a measure of the permeability of the lung vessels and as such can classify the type of lung oedema (hydrostatic vs. permeability caused)
EVLWPVPI =
PBVPBV
EVLW
Introduction to PiCCO Technology – Pulmonary Permeability
permeability
PVPI normal (1-3) PVPI raised (>3)
Classification of Lung Oedema with the PVPI
Difference between the PVPI with hydrostatic and permeability lung oedema:
Lung oedema
hydrostatic
PBV
EVLW
PBV
EVLW
PBV
EVLW
PBV
EVLW
Introduction to PiCCO Technology – Pulmonary Permeability
EVLWI answers the question:
Clinical Relevance of the Pulmonary Vascular Permeability Index
PVPI answers the question:
and can therefore give valuable aid for therapy guidance!
How much water is in the lungs?
Why is it there?
Introduction to PiCCO Technology – Pulmonary Permeability
Relevance of EVLW- Management
101 patients with pulmonary edema were randomized to a pulmonary artery catheter (PAC) management group in whom fluid management decisions were guided by PCWP measurements and to an Extravascular Lung Water (EVLW*) management group using a protocol based on the bedside measurement of EVLW *.ICU days and ventilator-days were significantly shorter in patients of the EVLW* group.Mitchell et al, Am Rev Resp Dis 145: 990-998, 1992
22 days 15 days9 days 7 days
* *Ventilation days ICU daysn=101
EVLW* groupPAC groupEVLW* groupPAC group
Normal rangesParameter Range Unit
CI 3.0 – 5.0 l/min/m2
SVI 40 – 60 ml/m2 GEDI 680 – 800 ml/m2
ITBI 850 – 1000 ml/m2
ELWI* 3.0 – 7.0 ml/kgPVPI* 1.0 – 3.0 SVV 10 %PPV 10 %GEF 25 – 35 %CFI 4.5 – 6.5 1/minMAP 70 – 90 mmHgSVRI 1700 – 2400 dyn*s*cm-5*m
Thermodilution Parameters• Cardiac Output
CO• Global End-Diastolic Volume
GEDV• Intrathoracic Blood Volume
ITBV• Extravascular Lung Water
EVLW• Pulmonary Vascular Permeability Index PVPI
• Cardiac Function IndexCFI
• Global Ejection FractionGEF
Pulse Contour Parameters• Pulse Contour Cardiac Output
PCCO• Arterial Blood Pressure
AP• Heart Rate
HR• Stroke Volume
SV
• Stroke Volume Variation SVV
• Pulse Pressure Variation PPV
• Systemic Vascular Resistance SVR
• Index of Left Ventricular ContractilitydPmx
Parameters measured with the PiCCO-Technology
Lithium Dilution Monitoring Combines the techniques of lithium dilution (lidco and lidcoplus) and pulse contour analysis (pulseco)
Small dose of lithium is injected into a peripheral vein and an ion selective electrode is attached to a peripheral arterial line
The area under the curve of a plot of lithium concentration against time allows accurate calculation of the cardiac output.
PulseCO is calibrated
provides ‘beat-to-beat’ cardiac output measurement
uses catheters which are likely to be already in place
The total dose of lithium is small and is clinically insignificant.
Calibration is recommended every 8 hours, or after any significant change in the patient’s clinical condition.
The system cannot be used for patients taking lithium and those who have recently received vecuronium or atacurium.
• Uses the arterial pressure waveform to Measure COO
• The difference over other monitors (such as the LiDCO®) is that it does not need to be calibrated with an indicator
• Application of advanced statistical principles to the arterial pressure tracing Result in the creation of a proprietary algorithm
• Recalibrates itself constantly
• By measuring the arterial pressure over a 20 s period at 100 Hz, the• system obtains 2000 data points for analysis
• The standard deviation of these points is then compared with empirical data stored in the proprietary algorithm of the software correlating the standard deviation of the arterial pressure measurements with the appropriate SV.
• The FloTrac® is also able to account for changes in arterial compliance which allows for the device to remain accurate and reliable during periods when CO, vasomotor tone or both are changing.
Studies evaluating the 1st -generation and 2nd generation
FloTrac showed poor agreement compared with
intermittent thermodilution,
their accuracy remained clinically
unacceptable.
The 3rd generation software claims to
have overcome these problems
do not show improved accuracy in comparison with
older versions
Partial Co2 rebreathing fick monitoring (NICO)
• The NICO monitor uses a rearrangement of the fick equation for CO2 elimination.
• Can only be used for patients who are intubated• The partial rebreathing technique gives a better approximation of cardiac output in patients who are less critically ill and have normal alveolar gas exchange
• Best suited for monitoring trends in critically ill patients with stable lung function rather than diagnostic interpretation
Gama de Abreu M, Quintel M, Ragaller M, et al: Partial carbon dioxide rebreathing: A reliable technique for noninvasive measurement of nonshunted pulmonary capillary bloodflow.Crit Care Med1997; 25:675–683
Jopling MW: Noninvasive cardiac output determination utilizing the method of partial CO2rebreathing. A comparison with continuous and bolus thermodilution cardiac output.Anesthesiology1998; 89:A544
Thoracic bioimpendance• The technique depends on the change in bioimpedance of the
thoracic cavity during systole• A series of ECG type electrodes are placed on the thorax and
neck. A small, non-painful current is passed and measurements made
Oesophageal doppler• Was first described in 1971 and later refined in 1989
PRINCIPLE• Flow in a cylinder is equal to the area of the cross-section of the
cylinder times the velocity of fluid in cylinder
• Movement of blood is pulsatile and the velocity changes with time
• The velocity can be characterized by the area under the velocity-time curve between two points in time
• area under the curve computed mathematically as the integral of the derivative of volume over time (dv/dt) from T1 to T2,
• Time integrated velocity.
• Stroke volume (sv) is calculated by multiplying the cross sectional area by the time-integrated velocity.
The probe is approximately the size of a nasogastric tube
Doppler transducer (4 MHz continuous or 5 MHz pulsed wave, according to the type of device) at the tip of a flexible probe.
similar technique to placing a nasogastric tube
measures velocity not flow,
descending aorta only receives a portion of the cardiac output,
only an estimate of cardiac output based on descending aortic blood flow
important consideration is the importance of positioning
To have a good approximation of velocity, the Doppler beam should bewithin 20°of axial flow
cross-sectional area of the aorta is actually dynamic and isdependent on the pulse pressure and aortic compliance
flow in the aorta is not always laminar
Oesophageal Doppler
Ultrasound beam is directed at the descending thoracic aorta
The magnitude of Doppler shift is directly proportional to the velocity of the blood flow
Stroke volume = Mean blood velocity x Ejection time x Aortic cross-sectional area
probe inserted via nasal or oral route is advanced and rotated until characteristic descending aortic trace is obtained and optimized.
Normal ranges FTc: Flow Time corrected measure of cardiac preload 330 -360 milliseconds
PV: Peak Velocity-an index of contractility
20 yrs: 90 - 120 cm/sec 50 yrs: 70 - 100 cm/sec 70 yrs: 50 -80 cm/sec
Concurrent shifts in FTc and PV indicates changes in after load
MA: Mean Acceleration depends on the patient
SD: Stroke Distance depends on the patient
Narrow waveform base, decreased FTc characteristic of hypovolaemia
Same patient after fluid resuscitation
•Minimally invasive•Real time measurement•Rapid insertion. Results available within few minutes.•Minimal technical skill required•Short training period•Good trend monitor
Advantages
•Interference by nasogastric tube•Dislodgement by movement. This may result in loss of signal or may result in changes in monitored values•Some patients contraindicated (eg post-oesophagectomy, oesophageal injuries)•Absolute values of cardiac output not very accurate
Disadvantages
Ballard C, Cohen Y, Fosse JP, et al: Haemodynamic measurements (continuous cardiac output and systemic vascular resistance) in critically ill patients: Transoesophageal Doppler versus continuous thermodilution.Anaesth Intensive Care1999; 27:33–37
Valtier B, Cholley BP, Belot JP, et al: Noninvasive monitoring of cardiac output in critically ill patients using transesophageal Doppler. Am J Respir Crit Care Med1998; 158: 77–83
Madan AK, UyBarreta VV, Shaghayegh AW, et al: Esophageal Doppler ultrasound monitor versus pulmonary artery catheter in the hemodynamic management of critically ill surgical patients.J Trauma1999; 46:607–611
Why do we need dynamic indices???
To determine if a patient will be preload responsive before the
volume is given
Rely on the changing physiology of heart lung interactions to
determine whether a patient will benefit
from increased preload
PHYSIOLOGIC RATIONALE OF DYNAMIC INDICES
Wall stress at the end of diastole
Direct measurement of wall stress in vivo is difficult; end diastolic volumes or pressures have been used as proxies
significant limitations
An accurate measure of preload at a point in time does not necessarily reflect preload responsiveness
PRELOAD
Frank-Starling curve
Fluid administration does not always result in cardiac output enhancement.
This comes from the curvilinearity of the frank–starling relationship:
If the heart is operating on the initial and steep part of the curve,it should have some preload reserve, and any increase in cardiac preload results in an increase in stroke volume.
If the heart is operating on the distal and flat part of the frank–starling curve(absence of preload reserve), no significant increase in stroke volume is expected from volume loading.
Assessment of PRELOAD is not assessment of PRELOAD DEPENDENCE
Stroke volume
Ventricular preload
normal heart
failing heart
preload-dependence
preload-independence
•Dynamic indices apply a controlled and reversible preload variation and measure the hemodynamic response.
Effects of mechanical ventilation on left and rightventricular stroke volume
Increased intrathoracic pressure
• Compression of the vena cava• Increased right atrial pressure.
Decreased preload to the right heart because
Decrease in right ventricular (rv) preload leads to
A decrease in RV output
Decrease in pulmonary artery blood flow, LV filling, and LV
output.
mechanisms postulated to increase LV SV variation with PPV include changes during inspiration, caused by increased
transpulmonary pressure
Increased RV afterload
Increased LV preload
Decreased LV afterload.
The end result of these pressure changes is
LV SV increases, while
RV SV decreases during positive pressure inspiration.
The delay of pulmonary blood transit time results in decreased RV SV translating to a decreased LV SV a few heartbeats later (ie, usually during expiration)
These phasic differences are exaggerated in the setting of hypovolemia for several reasons:
The underfilled vena cava is more collapsible
The underfilled right atrium is more susceptible to increased intrathoracic pressure
More of the lung demonstrates the physiology of West Zones 1 and 2 which effectively increases RV afterload
Larger changes are seen when operating on the steeper portion of the Frank-Starling curve.
This increased variation in pressures between the inspiratory phase and the expiratory phase can be used to identify hypovolemia and volume responsiveness, and is
the basis for Cavallaro’s group A and B indices, including stroke volume variation (SVV) and pulse pressure
variation.
CLASSIFICATION OF DYNAMIC INDICES OF FLUID RESPONSIVENESS
Functional hemodynamic monitoring and dynamic indices of fluid responsiveness F. CAVALLARO, C. SANDRONI, M. ANTONELLI MINERVA ANESTESIOL 2008;74:123-35
GROUP A: Indices based on mechanical ventilation-induced variations of stroke volume and stroke
volume-derived parameters
GROUP B: Indices based on
mechanical ventilation-induced variations of non-
stroke volume-derived parameters
GROUP C: Indices based on preload-
redistributing maneuvers different
from standard mechanical ventilation.
Stroke volume variation (SVV)
SVV examines the difference between the
SV during the inspiratory and
expiratory phases of ventilation, and requires
a means to directly or indirectly assess SV.
PiCCO , LiDCO and FloTrac sensor monitors
uses pulse contour analysis through a
proprietary formula to measure cardiac output
and SVV.
Pulse Pressure Variation
Difference between arterial systolic and diastolic pressure
the PP during inspiration with PP during expiration demonstrates the
degree to which the PP is preload-limited
Pulse pressure variation (PPV)
Influenced by sv and the arterial compliance.
As comparison is being made during a single
respiratory cycle, change in arterial compliance
theoretically should be minimal.
Analysis of the PPV thus can be used to predict volume
responsiveness
In mechanically ventilated patients with septic shock,
a PPV of 13% identified patients who had a greater
than or equal to 15% increase in cardiac output
in response to volume expansion with a
sensitivity of 94% and specificity of 96%
PLETHYSMOGRAPHYpulse oximeter plethysmographic waveform differs from the arterial pressure waveform by measuring volume rather than pressure changes in both arterial and venous vessels
Examining amplitude variation between inspiration and expiration phases
Variation in the plethysmographic waveform has been referred to by many names: change in pulse oximetry plethysmography (dPOP), ventilation-induced plethysmographic variation (VPV)
VPV (VPV(%) :([Max amplitude - Min amplitude]/[(Max amplitude + Min amplitude)/2])
Plethysmography variability index (PVI):
obtained from plethysmographic waveforms displayed on pulse oximeters .
used for the purpose of fluid responsiveness.automated measure of the dynamic change in the “Perfusion Index” that occurs during a respiratory cycle
Its advantage is that it can be automatically calculated and displayed on the screen of the pulse oximetry monitor
•1 - no pleth variability •100 - maximum pleth variability
PVI Calculation Automated
measurement Changes in
plethysmographic waveform amplitude over the respiratory
cycle PVI is a percentage from 1 to
100%:
Large inter- and intra-individual variation in
VPV in 14
Poor agreement between VPV and PPV
Proprietary signal processing by different
manufacturers may alter the raw data such that it interferes with
the use of the
Waveform for purposes other than oxygen
saturation monitoring. For example, the auto–gain function on most pulse oximeters will conceal amplitude
changes
• Evidence for pulse oximetric variation? – not validated
Respiratory variability of the inferior vena cava
The inferior cavae are distensible blood vessels whose diameters and flow vary with respiration
The IVC enters the right atrium almost immediately after crossing the diaphragm.
Extramural pressure = abdominal pressure; intramural pressure = right atrial pressure.
Steep slope at low distention and a plateau at full volume.
In IPPV, increase in pleural pressure increases right atrial pressure
Increases transmural pressure of the IVC – increases the IVC diameter
In hypovolemic patients these diameter changes are larger than if the IVC is full (ie, on the flat part of the pressure volume curve)
• Distensibility index of the IVC (divc) defined as (Dmax-Dmin)/Dmin and expressed as a percentage predictive of fluid responsiveness with a sensitivity of 90% and a specificity of 90%• DDivc as maximal – minimum IVC diameter divided by the mean of the two values and expressed as a percentage.DDivc of 12% predicted fluid responsiveness with a positive predictive value of 93% and negative predictive value of 92%
Potential for predicting preload responsiveness in septic patients.
Phasic variation of svc diameter may be more accurate, as it is not influenced by intra-abdominal pressure.,
It necessitates a transesophageal approach.
Validation of these concepts in large, multicenter trials is warranted.
• Cyclical swing in intra-thoracic pressure• Swing in IVC size means preload is along the
steep part of the Starling Curve
IVC size variation = Max Diam – Min Diam / Mean x 100
Cautions Regarding Cavallaro Group A And B Indices
Requires positive pressure controlled ventilation
Sinus rhythm required. Arrhythmia or frequent extra systoles result in altered SV and invalidate these tools to predict volume responsiveness.
Require invasive arterial blood pressure
A single value never should replace clinical judgment. A high PPV value in a normotensive patient with evidence of normal tissue perfusion does not mean that person requires volume expansion
Further investigation of these techniques in the setting of vasoactive medications is needed.
How extremes of ventilation (ie, low tidal volume, high respiratory rate, high positive end-expiratory pressure [peep]) affect group a and b indices is not yet clear
Further investigation of these indicators in the setting of the open abdomen or
Open thorax is needed before their use should be relied upon in these populations.
Passive Leg Raising
Reversible volume
Elevating a patient’s legs allows a passive
transfer of blood from the lower part of the
body toward the central circulation.
The amount of blood transferred from the
legs is variable and has been estimated to be
between 150 to 750 ml .
During plr, shift of fluid from the lower part of the body to the thorax
results in increased cardiac output.
Venous return = Mean Systemic Pressure – RAPPLR Increased MSP venous return RV output LV filling Acts as a brief, totally reversible fluid challenge
Fluid responsiveness cannot be assessed based on a single
CVP, PCWP, etc
Should be based on dynamic changes in
response to change in preload
Positive pressure ventilation and SLr produce transient preload changes
PLR can be used in spontaneously
breathing patients and in patients not
in sinus rhythm
Several studies have determined that PLR
is effective in determining fluid-
responsiveness
The increase in preload from the maneuver is reversed completely when the legs are returned
to horizontal,
It is safe even in cases in which increasing blood volume may be harmful
Good specificity and sensitivity
PLR induced increase of SV by 12.5%, resulted in an increase of stroke volume by 15% after fluid challenge with 500 mls.
Increase of cardiac output or SV of greater than 12% with PLR predicted volume responsiveness.
Sensitivity and specificity of 81% and 93%, respectively.
The hemodynamic response to PLR is rapid and transient real-time assessment of cardiac output is needed,
It is not clear how much blood is autotransfused,
How much this varies between patients and patient populations, and if the variation is significant.
Vasoconstrictors, increased intra-abdominal pressures, and elastic compression stockings all may have an impact on validity of plr; further
studies are needed to clarify these issues.
Limits of Preload-Responsiveness
• Preload Preload-responsiveness• Preload-responsiveness Need for fluids• The means of altering preload matters
• Size of Vt, passive leg raising, spontaneous breaths
• Different measures of pressure or flow variation will have different calibrations
Pinsky Intensive Care Med 30: 1008-10, 2004
Where does echocardiography stand?• Tool for “functional” haemodynamic monitoring• Help predict fluid responsiveness• LV, RV, valve function• Acute PE, pericardial effusion• Clots
LVOT AREA = ∏ (3.14) X (D/2)2
Velocity – Time Integral
Distance travelled by the blood is a function of the velocity and time = velocity – time integral. Otherwise called stroke distance. VTI x area of the LVOT
• To calculate SV : velocity across the aorta or LVOT & CSA of aorta• As velocity/flow is not constant : measured as VTI• View the heart on the 5CV • Switch on the PWD• Place the cursor or sampling volume at the level of LVOT• Ensure that line of the cursor should be in line with LVOT• Once u switch on PWD u get waveform / envelope formed by flow
across LVOT• Trace out the Evelope which will give VTI from the inbuilt software
Stroke Vol = VTI x CSA
Measure LVOT diameterPlax viewFreeze the frame in systoleAortic leaflets will be fully open and apposed to the aortic valve
LV systolic function• To measure EF by teicholz method,• Parasternal long axis view• Place the M mode cursor at right angles to the septum and the free
wall of the LV.• On the m mode, measure the systolic diameter and the diastolic
diameter. • Use the calculation menu on the echo machine to measure ef by
teicholz method.
LV dysfunction• LV dysfunction common in the ICU• Ventricular performance may be markedly impaired in sepsis• EF may be unreliable because of the low SVR• Important for haemodynamic optimisation- fluid or inotrope?
DCM WITH POOR FUNCTION
POOR LV FUNCTION
PSAX OF LV FAILURE
RV dilatation/dysfunction• Massive PE, ARDS• Excessive PEEP, RV afterload increase due to other causes• RV infarction• Air, fat embolism• Sickle cell crisis• Myocardial contusion, sepsis• RVEDA/LVEDA 0.6 TO 1.0 = moderate• >1 = severe, >2 = extreme• Eye balling – as large or larger than LV on A4C
Pulmonary embolism
Pulmonary Artery
Pulmonary Embolism
PA pressure • Tricuspid jet • Measure tricuspid gradient = 4V2
• Tricuspid gradient (TG) = RVpsys – RApsys
• RVpsys = TG + RApsys
• RApsys = CVP• RVpsys = PAsys = TG +CVP• Place CWD on regurgitent Jet• Measure the depth of the waveform from baseline
Pericardial Effusion• Echo free space around the heart • Distinguish between pericardial and pleural effusions• Cardiac tamponade
RA CLOT
Mitral stenosis