cardiac output and monitoring anaesthesia.pptx

cardiac output and monitoring

1. CARDIAC OUTPUT AND ITS MONITORING PRESENTED BY : DR.ANIL PADALA MD ANAESTHESIA)

2. OBJECTIVES Introduction Cardiac output Factors affecting cardiac output Physiological variations of cardiac output Pathological variations of cardiac output Methods /principles used to measure CO Cardiac output monitoring

3. Introduction CO monitoring is a hemodynamic parameter Acts as a guide to appropriate fluid resuscitation and estimates whole body perfusion delivery. In the critically ill or pt’s undergoing major surgeries, CO monitoring is standard practice. Over the last three decades, the PAC TD technique have been the gold standard for measurement of CO.

4. CARDIAC OUTPUT DEFNITION: Amount of blood ejected by each ventricle per minute. CO = SV X HR SV - stroke volume HR - heart rate Normal values CO : 5 Lt/min(4-6.5lt/min) HR : 70 beats/min(60-100b/min) SV : 70-80 ml/ beat

5. Factors Effecting Heart Rate Autonomic Innervations Harmones Fitness Levels Age Factors Effecting Stroke Volume Heart Size Fitness Levels Gender Contractractility Duration Of Contraction Preload Afterload Heart Rate Stroke volume CARDIAC OUTPUT = HR * SV

6. FACTORS EFFECTING CARDIAC OUTPUT Heart rate When heart rate increases , cardiac output also increases. Any factor which changes heart rate will also changes output. Force of contraction of heart When the force of contraction of heart increases, stroke volume will increase. Therefore cardiac output will increase. Blood volume When blood volume increases cardiac output increases. Venous return

7. Physiological variations of cardiac output Age: Cardiac output is more in adults than in children because blood volume is more. Gender : Cardiac output is more in male than females. Altitude: Cardiac output increases at high altitude places. Pregnancy: Cardiac output increases during pregnancy. Exercise : Cardiac output increases during exercise Emotion: Cardiac output increases during emotional expressions

8. PATHOLOGICAL VARIATION OF CO PATHOLOGICAL INCREASE: Hyperthyroidism Fever PATHOLOGICAL DECREASE: Hypothyroidism Hypovolemia Haemorrhage Myocardial infarction

9. PRINCIPLES TO MEASURE CO Fick’s Principle Dilution Techniques Doppler Monitering Transesophageal Doppler Monitoring Pulse Contour Analysis Thoracic Impedance Thoracic Bioreactance Echocardiography Magnetic Resonance

10. FICK’S PRINCIPLE By- Adolf Fick (German physiologist) 1st described ,utilized o2 conc. In arterial & venous blood samples to compute animals CO. Measures blood flow through any organ , that add or removes substances from blood. CO = pulmonary blood flow (lungs add o2 and removes co2 from blood) Q = M/(V-A) Q – volume of blood that flows through an organ M – no. of moles of substance the organ add to blood V & A – venous & arterial conc. Of substance

11. DILUTION TECHNIQUES Stewart --- Inject NaCl into central circulation Hamilton --- known quantity of drug into pulmonary artery Measure subsequent conc. In Femoral Artery Measure conc. In Peripheral Artery to correct recirculation of dye achieved curve is Semilogorithmically replotted

12. DILUTION TECHNIQUES… Feglar --- Instead of dye ,cold solution is injected (Thermodilution technique) Measure blood temperature distally The CO is calculated using Stewart- Hamilton equation Swan --- Developed PAC ,A Multi lumen flow directed balloon tipped catheter GOLD STANDARD for CO monitoring

13. DILUTION TECHNIQUES… Pulmonary artery thermodilution ---- TD principle applied to PAC a electric filament into Rt ventricular bulb ,15 – 25cm proximal to PAC Intermittently heats the blood as it flows through RV Thermistor at catheter tip measures resultant temp. Continues TD method correlate well with intermittent bolus method Continues CO trend is provided every 30-60sec ,but Avg CO values for last 5-15min is reflected.

14. DOPPLER MONITERING Measures velocity of flow Principle--- when signal source approach observer inc. in observed frequency of signals & vice versa CO is measured based on diameter of aorta/ distribution of CO to descending aorta/measured flow velocity of blood in aorta. TRANSESOPHAGEAL DOPPLER MONITORING : Initially , suprasternal transthoracic USG/doppler probes were used to determine CO. But limited bcz of instability of probe position for repeated measurement

15. The esophageal probes ,gained better acceptance bcz oesophageal smooth muscle tone naturally maintain probe in place for extended time intervals Proximity of oesophagus to aorta( reduces signal interference improving measurement).

16. Pulse contour analysis It is based on relationship b/w BP , SV , arterial compliance & SVR If arterial compliance & SVR are known ,based on arterial pressure waveform SV & CO can be calculated. SV = Area under systolic portion of arterial pulse /aortic impedence CO = HR X SV. Commercially available pulse contour systems used to measure CO by indicator dilution method P t demographics & physical characteristic ( to estimate arterial impedence ) It need neither preloaded data nor calibration.

17. Thoracic impedance Least invasive It suggests – thorax is a cylinder that is perfused with fluid with high resistance It detects – electrical changes that occur with altering fluid levels in thorax Levels changes as LV contracts & blood flows into thoracic aorta corresponding change in resistance in thorax bcz the fluid level in aorta inc. This change in impedance measured as change in voltage passing b/w 6 surface electrodes 2 (either side of neck) 4 (lower thorax)

18. Thoracic impedance… The current transmitted by outermost set is sensed by innermost set of electrodes. The rate of change of impedance is believed to be related to instantaneous blood flow in aorta & is used to measure hemodynamic parameters Thus, bioimpedance measures amplitude of voltage change across the thorax

19. THORACIC BIOREACTANCE Modification of impedance technology Pulsatile changes in aortic fluid volume induce changes in phase of thoracic impedance Phase shifts are because of pulsatile flow ; underlying tissue fluids & changes in them doesn’t induce phase shifts & doesn’t affect flow information It tracks electric currents traversing chest & derives flow information from phase component of thoracic impedance

20. ECHO CARDIOGRAPHY T he movement of ant. & post. Ventriculat walls &EF can be measured by 2D echo cardiography MAGNETIC RESONANCE Accurate way to measure flow in aorta R esonance properties of protons in nucleus do change with respect to velocity

21. CARDIAC OUTPUT MONITORING INVASIVE PA catheter MINIMALLY INVASIVE PULSE CONTOUR ANALYSIS: CALIBRATED: PICCO , LiDCO UNCALIBRATED: Flowtrac, PRAM PULSED DOPPLER TECHNOLOGY USCOM; esophageal doppler device APPLIED FICK PRIN CIPLE - NICO BIOIMPEDENCE/REACTANCE - ECOM, NICOM

22. PULMONARY ARTERY CATHETER : Measures: Intracardiac pressures PA pressures Cardiac output Oxygen saturation

23. PULMONARY ARTERY CATHETER …

24. INDICATIONS: CONTRAINDICATIONS: IHD, Cardiogenic shock RV failure Septic shock Periop: high risk cardiac pts Tricuspid or pulm valve mechanical prosthesis Right heart mass( tumor or thrombus) Tricuspid or pulmonary endocarditis PULMONARY ARTERY CATHETER…

25. PULSE CONTOUR CO MONITOR(PICCO): Combination of trans-pulmonary thermodilution and pulse contour analysis. It requires a central venous line (internal jugular/ subclavian) & an arterial catheter placed in bigger systemic arteries (femoral/axillary) It determines TDCO Continuous CO using pulse contour method Intrathoracic blood volume Extravascular lung volume

26. Pulse contour analysis: Continuous pulse contour cardiac analysis (PCCO) Arterial blood pressure (AP) Heart rate (HR) Stroke volume (SV) Stroke volume variation (SVV) Systemic vascular resistance (SVR ) Index of left ventricular contractility Intermittent thermodilution : Transpulmonary cardiac output (CO) I ntrathoracic blood volume (TBV) Extravascular lung water (EVLW) Cardiac function index (CFI)

27. LITHIUM DILUTION CO MONITOR(LIDCO): Lithium indicator dilution Continuous, monitoring of CO, in pts with preexisting peripheral arterial line access Based on real time pulse power analysis rather than pulse pressure analysis via the pulse CO algorithm, which doesn’t rely on the arterial waveform morphology & needing only peripheral arterial catheter. Assumption that pulse power has a linear relationship with flow. it uses an algorithm to detect CO Minimally invasive Safe Boluses of 0.5-2ml of lithium chloride are each time injected through a peripheral or central line & Li conc. Is measured through aspiration of blood from arterial catheter using a Li sensitive electrode attached to catheter that generates voltage

28. Since, the electrode has low sensitivity for distinguishing Li from N a, A correction factor is applied for N a plasma levels & baseline voltage is applied that helps differentiate the conc. Of 2 cations. They use the same pulse pressure algorithm to track continuous change in SV. This algorithm is based on assumption that net power change in system in a heart beat is the difference between amount of blood entering the system and amount of blood flowing out peripherally Advantages: Main adv – not naturally occur in plasma (high signal to noise ratio), followed by rapid redistribution time & insignificant 1st pass loss from circulation. Safe ,easy & accurate (can be set up in 5min by a trained nurse). Can be used in conscious pt in perioperative settings Averts necessity for an invasive PAC & associated morbidity. LITHIUM DILUTION CO MONITOR(LIDCO)…

29. INDICATIONS: Acute heart failure; h/o of cardiac disease; complex circulatory situations Gram negative sepsis,drug intoxication,acute renal failure Severe hypovolemia and fluid shifts Medical emergencies CONTRAINDICATIONS: If already on Lithium(lack of accuracy) Muscle relaxant drugs( over estimation of CO) Weight less than 40kg First 3 months of pregnancy Pts with severe peripheral arterial vasoconstriction, aortic valve regurgitation & with aortic balloon pumps. LITHIUM DILUTION CO MONITOR(LIDCO)…

30. FLOTRAC MONITOR UNIQUE – doesn't require central venous access or placement of PAC to obtain hemodynamic data. It utilizes existing radial /femoral arterial line(arterial waveforms) that is attached to its monitoring unit and obtains data on CO, CI, SVR, SVI, SVV. Flotrac sensor is a key component for operation of monitoring system. The sensor replaces traditional arterial line transducer & provides 2 pressure cable connections 1)conventional arterial waveform monitoring 2) connects directly to monitoring unit Advantage – ease of use invasiveness quick setup ability to use it in different clinical setting It incorporates individual pt specific demographic data .

31. FLOTRAC MONITOR…

32. It analyses , arterial pressure waveform 100 times/sec - every 20sec for total of 2000 data points for use in its algorithm. HR is determined based on peaks of arterial waveform SV is calculated by 3 different variables arterial pulsatility resistance compliance Pulse pressure is difference of systolic &diastolic BP & is comparative to flow. Pulse Pressure proportional to SV SVV= variation of SV from mean of arterial waveform with every beat of heart if SVV > 13% , indicate need for volume replacement SVV = max.SV – min. SV mean SV

33. If SVV<13% , SVI must be considered. Normal SVI(40- 50mm Hg) ,may indicate -- - need for vasopressor Low SVI (<40mm Hg) may specify need --- - for ionotrope High SVI(>50mm Hg) may require -- - a diuretic. Assesment of svv intended to predict fluid responsiveness.

34. FLOTRAC MONITOR… INDICATIONS : Currently, it is recommended for pts that are 100% mechanically ventilated & not spontaneously breathing CONTRAINDICATIONS : Arrythmias can change the arterial pressure waveform, altering SVV Elevated levels of PEEP can erroneously inc. SVV Large changes in vascular tone or vasodilation –inc. SVV ADVANTAGES: Fluid optimisation by SVV&CO improve hemodynamics; thus D ec rease length of hospital stay A n earlier return to bowel function after major operation s Decrease in postop nausea & vomiting Provides hemodynamic data without need for calibration or central venous access.

35. PRESSURE RECORDING ANALYTICAL METHOD(PRAM) Another method to estimate SV continuously without calibration or demographic data. Based on mathematic assessment of pressure signal obtained by arterial line without calibration. Similar to other devices that use pulse contour analysis, the accuracy of PRAM derived CO is affected by quality of pressure signal & by factors that interfere with ability to detect pressure signal. SV proportional to ---- area under diastolic part of arterial pressure wave. With PRAM, SV is calculated for each beat & CO per beat is derived by SV X HR CO is presented as mean value of 12 beats

36. ESOPHAGEAL DOPPLER: Esophageal doppler monitor ,which is based on doppler effect in order to measure the velocity of blood flow was 1st introduced in 1970 as a non invasive means to measure CO ED monitoring is undertaken with a single use probe , which is placed in esophagus via nose or mouth The device generates a low frequency ultra sound signal, which is reflected by RBC travelling down the aorta. The reflected signal can be used to determine flow velocity.

37. ESOPHAGEAL DOPPLER… Diameter of aorta is obtained by built-in nomogram or by direct measurement using M-mode echocardiography ED has the ability to measure corrected flow time ( FTc ) as a measure of cardiac preload FTc –duration of flow during systole corrected for a HR of 60/min & ability to respond to a fluid challenge is best determined by FTc . Has good correlation with PAC .

38. ADVANTAGES: Useful in peri operative hemodynamic optimization studies. Reduction in complication rates and hospital length of stay. DISADVANTAGES: As it measures desc. a orta blood flow,not accurate in aorti c pathology /compression / due to abnormal upper to lower body blood flow distribution Doppler probes are smaller than conventional TEE probes & position may change frequently. Even small misalignments of USG beam with blood flow will lead to underestimation of flow ESOPHAGEAL DOPPLER…

39. Operator dependent device &require 10- 12 insertions to obtain accurate measurements. Aortic cross sectional area is always dynamic in any individual due to changes in Pulse pressure, vascular tone, aortic compliance, volume status or catecholamine use, hence the use of normogram may result in less accurate CO Normogram assumes that flow is laminar & any turbulent flow in aorta reduce measurement accuracy. ESOPHAGEAL DOPPLER…

40. ESOPHAGEAL DOPPLER…

41. ULTRASOUND CARDIAC OUTPUT MONITOR(USCOM) Alternative to esophageal route, the transthoracic approach(USCOM) may be used to measure CO. It targets pulmonary & aortic valves using doppler technology accessed via the parasternal & suprasternal windows It uses continuous-wave doppler ultrasound & can measure CO. The flow profile is displayed on USCOM monitor with spectral display showing variations of blood flow velocity with time It allows for real time ,beat-beat quantitative evaluation of 14 CO parameters : CI, CO, peak velocity of flow, velocity time integral, HR, ejection time percent, SV, SVI, SVV, SVR, SVRI, minute distance, mean pressure gradient & flow time

42. ULTRASOUND CARDIAC OUTPUT MONITOR(USCOM)… ADVANTAGES : The device is highly portable, weighing <7kgs & is powered by a internal battery. Primary applications in emergency HF, resuscitation, hemorrhage, sepsis, ICU for post surgical monitoring, HF,MI, & in pediatrics. DISADVANTAGES: Takes much longer time to become sufficiently familiar with different signal sounds &patterns to recognize when a truly reliable has been obtained. Significant experience & psychomotor skill is needed to be able to acquire clinically reliable data.

43. Non Invasive Cardiac Output Monitor(NICO) The NICO system applies Fick principle to co2 in order to obtain CO noninvasively in intubated, sedated & mechanically ventilated pts using disposable rebreathing loop that is attached to the ventilator circuit. It is unique as it calculates: Alveolar ventilation( MValv ): reflects effective ventilation. Co2 elimination(VCO2):reflects changes in ventilation & perfusion. Total dead space to tidal volume ratio( Vd /Vt): estimates efficiency of cvs It consists of 1)mainstream IR sensor to measure co2 2)disposable airflow sensor 3)pulse oximeter

44. Non Invasive Cardiac Output Monitor(nico)... Co2 production (vco2) calculated from---- minute ventilation & its co2 content Arterial co2 content (caco2) from----end-tidal co2,with adjustment for slope of co2 dissociation curve & degree of dead space ventilation Every 3min ,a partial rebreathing state is generated using the attached rebreathing loop, which results in inc. end-tidal co2 & reduced co2 elimination. Assuming CO doesn’t change significantly b/w normal & rebreathing states, the difference b/w normal & rebreathing ratios are used to calculate CO. CO is proportional to---- change in co2 elimination /change in Etco2

45. Non Invasive Cardiac Output Monitor(nico)... Limitations: Only in mechanically ventilated pts. Not accurate in variable ventilatory settings(mech. Assisted spontaneous breathing) Unreliable in severe chest trauma, significant intrapulmonary shunt, dead space ventilation, low minute ventilation & high CO

46. ELECTRIC BIOIMPEDENCE CO MONITORING(ECOM) Impedance is the resistance to the flow of electric current. Blood & other fluids are excellent conductors of electricity &have low impendence compared to bone, tissue & air. Blood & fluid in lungs are most conductive in thorax. In impedence cardiography, 4pairs of electrodes & a set of ECG leads measure hemodynamic parameters. Each pair of electrodes is comprised of a transmitting & sensing electrode. 2 pairs of electrodes---base of neck on opposite sides 2pairs ---the level of sternal-xiphoid process junction directly opposite from each other. Dot electrodes define upper &lower limits of Thorax &distance b/w them is thoracic length.

47. ELECTRIC BIOIMPEDENCE CO MONITORING(ECOM)… A high frequency low amplitude AC current is introduced transmitting thoracic electrodes & sensing thoracic electrodes measure impedance associated with pulsatile blood flow in asc . Aorta By measuring ,impedance change generated by pulsatile flow& time intervals b/w the changes SV can be calculated. Impedance is inversely proportional to Blood flow Flow velocity Alignment of RBC during systole DISADVANTAGES: Inaccurate readings in motion artifacts, electrical interference, cardiac arrythmias, heart & lung pathologies & foreign bodies.

48. NON INVASIVE CARDIAC OUTPUT MONITORING(NICOM): Bioreactance noninvasive cardiac output monitoring is a modification of thoracic bioimpedance. Bioreactance – electrical resistance, capacitance & inductive properties of blood & biological tissue that induce phase shifts b/w a applied electric current & resulting voltage signal. Contrast to impedence, bioreactance technique analyses the frequency spectra variations of the delivered oscillating current When blood flows out of heart,phase shifts occur if alternating currents are applied across pts chest This approach is supposed to result in higher signal- to- noise- ratio & thus improved performance of device. Such phase shifts are conceptually similar to a frequency modulation used in radio transmission.

49. The phase shifts are measured continuously & have ben shown to relate almost linearly to blood flow in aorta. This results in less interfering from electric noise, pt movement, respiratory effort, lead placement & BMI It measues CO and also total fluid content(TFC). T 22 FC is affected by both intravascular & extravascular fluid in chest cavity, so indicator of changes in these fluid volumes. NONINVASIVE CARDIAC OUTPUT MONITORING(NICOM)…

50. My references Miller’s 9 th edition Barash 8 th edition Ann Card Anaesth .  2019 Jan-Mar; 22(1): 6–17.  Doi:  10.4103/aca.ACA_41_18 PMCID: PMC6350438 PMID:  30648673 World J Cardiol .  2014 Sep 26; 6(9): 1022–1029. Published online 2014 Sep 26. Doi:  10.4330/wjc.v6.i9.1022 PMCID: PMC 4176793 PMID:  25276302

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