Hemodynamic Monitoring

in ICU

Dr G.Sandeep

INTRODUCTION

Hemodynamic monitoring -cornerstone in the management of the critically ill patient

Identify impending cardiovascular insufficiency, its probable cause, and response to therapy.

Despite the many options available, utility of most hemodynamic monitoring is unproven

Why hemodynamic monitoring?

Physicians have developed a psychological dependence on feedback from continuous hemodynamic monitoring tools, independent of their utility

Effectiveness of hemodynamic monitoring to improve outcome limited to specific patient groups and disease processes for which proven effective treatments exist

IndicationsSummary of ACP/AHA/ACC Expert Panel

“To help direct management in medical patients in whom hemodynamics will alter treatment and clinical estimates are unreliable”

“To assist management of surgical patients” “To establish or assist in establishing specific

diagnoses” – Cardiac vs. non-cardiac pulmonary edema – VSD vs. MR in acute MI – Pericardial tamponade – RV MI

Rationale for Hemodynamic Monitoring

Monitoring device will improve patient-centered outcomes when coupled to a treatment which, itself, improves outcome

Time -crucial for early diagnosis of hemodynamic catastrophe -earlier therapy improves outcome in this situation

N Engl J Med 2001; 345:1368–1377

Hemodynamic Monitoring

Non Invasive

Clinical variables BP ECG Echocardiography O2 saturation

Invasive CVP SvO2, Mixed venous oxygen

saturation (from the central venous line

Arterial catheter Cardiac output PA Catheter

CLINICAL PARAMETERS

Blood pressure Heart rate and rhythm Rate of capillary refill of skin after

blanching Urine output Mental status

Blood pressure Proper Fit of a Blood Pressure Cuff

Width of bladder = 2/3 of upper arm

Lower edge of cuff approximately 2.5 cm above the antecubital space

Why A Properly Fitting Cuff?

Too small causes false-high reading

Too LARGE causes false-low reading

Normal blood pressure ≠hemodynamic stability

Hypotension (MAP < 65 mmHg) is always pathological.

NIBP

Errors in measurement :› Long stethoscope tubing› Poor hearing in observer› Calibration errors of

sphygmomanometer› Decreased blood flow in the extremity› Severe atherosclerosis (unable to

occlude)› Inappropriate cuff size› Too rapid deflation

Invasive Arterial Blood Pressure

Intra-arterial catheters ("art lines") are a reliable method to continuously monitor systemic blood pressure.

A NORMAL WAVE form will be: - Within the normal parameter of blood

pressure - Present a characteristic shape

- Synchronous with the EKG waveform

The normal peripheral arterial waveform will display the peak systolic pressure after the QRS.

This phenomenon reflects the time it takes the cardiac systolic pressure wave to reach the peripheral catheter and sensor.

The dicrotic notch reflects the closure of the aortic valve.

Overdamping: seen as a smooth waveform that loses the dicrotic notch.

It can be caused by air bubbles in the system, too many stopcocks, kink in the catheter or tubing, blood on the transducer, a clot in the catheter, an empty flush bag, aortic stenosis, vasodilation or a low cardiac output

Underdamping: seen as a sharp exaggerated waveform with overshoot of the systolic pressure and undershoot of the diastolic.

It can be caused by excessive tubing, excessive catheter movement, atherosclerosis, vasoconstriction, aortic regurgitation, hyperdynamic states and hypertension.

19

Supplies to Gather

Arterial Catheter

Pressure Tubing

Pressure Cable

Flush – 500cc NS

Potential Complications Associated With Arterial Lines

Hemorrhage

Air Emboli

Infection

Altered Skin Integrity

Impaired Circulation

21

Troubleshooting

Improper set-up and equipment malfunction are the primary causes for hemodynamic monitoring problems

Retracing the set-up process or tubing (patient to monitor) may identify the problem and solution quickly

22

Troubleshooting

Damped Waveforms

Pressure bag inflated to 300 mmHg

Reposition extremity or patient

Verify appropriate scale

Flush or aspirate line

Check or replace module or cable

23

Troubleshooting

Inability to obtain/zero waveform

Connections between cable & monitor

Position of stopcocks

Retry zeroing after above adjustments

What is the target BP ? No threshold BP that defines adequate organ

perfusion among organs, between patients, or in same patient over time

Based mainly on anecdotal experience, a systolic pressure of 100mmHg usual target, with HR < 120 /min-Controversial

Curr Opin Crit Care.2001; 7:422–430

MAP ≥ 65 mmHg -Initial target in septic shock,>40 mmHg in hemorrhagic shock and

> 90 mmHg in Traumatic brain injury –Level 1 B

Intensive Care Med. 2007; 33:575–590 International Consensus Conference Surviving sepsis Campaign 2008

ECG IN ICU

Arrhythmia Monitoring –Up to 95% of AMI have arrhythmia within 1st48 hrs

Up to 1/3 have VT. Early diagnosis and prompt treatment may improve survival

Heart rate variability may reflect prognosis

Ischemia Monitoring –Significant uncertainty to reliably detect myocardial ischemia and diagnose MI in critically ill patients

Evidence Ischemia in ICU related to pain, fluid

balance, fever, catecholamine levels, or other physical stresses

Hurford et al -worsening of ischemia (cont ECG ) in patients rapidly weaned from positive pressure to spontaneous ventilation

Continuous ECG monitoring in ICU detected a 6.4% incidence of ischemia during weaning

Patients with ischemia fail to wean more commonly

Echocardiography in ICU

Sole imaging modality that provides real-time information on cardiac anatomy and function at bedside

Ideally suited to early hemodynamic evaluation of patients with persistent shock despite aggressive goal-directed therapy

INDICATIONS –TTE IN ICU Hemodynamic instability–Ventricular failure–Hypovolemia–Pulmonary embolism–Acute valvular dysfunction–Cardiac tamponade

-Complications after cardiothoracic surgery -Infective endocarditis -Aortic dissection and rupture -Unexplained hypoxemia -Source of embolus

INDICATIONS –TEE IN ICU

High image quality vital–Aortic dissection -Intracardiac thrombus

–Assessment of endocarditis

Inadequately seen by TTE –Thoracic aorta -Left atrial appendage –Prosthetic valves

Inadequate image clarity with TTE –Severe obesity –Emphysema

Mechanical ventilation with high-level PEEP Presence of surgical drains, surgical

incisions, dressings Acute perioperative hemodynamic

derangements

Cardiac Tamponade in the ICU

Myocardial or coronary perforation secondary to catheter-based interventions (pacemaker lead insertion, central catheter placement, or percutaneous coronary interventions)

Uremic or infectious pericarditis Compressive hematoma after cardiac

surgery Proximal ascending aortic dissection

Blunt or penetrating chest trauma Complication of myocardial infarction

(e.g., ventricular rupture) Pericardial involvement by metastatic

disease or other systemic processes

Effect of ECHO in the diagnosis and management in ICU

Changes in management after TEE in 30–60% of patients leading to surgical interventions in 7–30%

Crit Care Med 2007; 35[Suppl.]:S235-4

Critically ill patients with unexplained hypotension, new diagnoses were made in 28% -leading to surgical intervention in 20% J Am Coll Cardiol 1995; 26:152–2

ECHO for diagnosis in patients with clinical evidence of ventricular failure and persistent shock despite adequate fluid resuscitation -Level 2 B

Intensive Care Med. 2007; 33:575–590 International Consensus Conference

ECHO –Final words All physicians in charge of critically ill patients

should be trained in goal directed echocardiography

Far from being competitive or conflicting, use of echocardiography by intensivists and cardiologists is complementary

German Society of Anesthesiology and Intensive Care Medicine-already developed their own certification

Brief (10 hrs) formal training in using a handheld ECHO system, intensivists able to successfully perform limited TTE in 94% of patients and interpreted correctly in 84% -changed management in 37% of patients.

Intensive Care Med .2008.34:243–249

Central Venous Pressure

Central Venous Pressure

Describes the pressure of blood in the thoracic vena cava, near the right atrium of the heart.

Normal Value: 2-6 mmHg (7-12 cm H2O) Reflects blood volume, RV performance, and

venous tone.

May reflect LV filling pressures in patients with normal LV function (EF > 40%), valves, and pulmonary status.

Principles of measurement

Leveling Standard reference level for assessment

sternal angle, 5 cm vertically above the mid-point of the right atrium -even when the person sits up at a 60ºangle

In supine patient, reference level -intersection of the fourth intercostal space with midaxillary line (3 mm Hg / 4.2 cm > sternal angle measurement )

Principles of measurement

CVP, should be made at end expiration -pleural pressure is closest to atmospheric pressure

intrinsic or extrinsic PEEP, pericardial fluid, or increased abdominal pressure can increase CVP

PEEP of 10 cmH2O, increases the measured CVP by less than 3 mmHg in normal lung and even less in deceased lung

40

Phlebostatic Axis 4th intercostal space, mid-axillary line

Level of the atria

(Edwards Lifesciences, n.d.)

Potential Uses of the CVP

CVP only elevated( > 10 mm Hg ) in disease, but clinical utility of CVP as a guide to diagnosis or therapy has not been demonstrated

If CVP is ≤ 10 mmHg then CO decrease when 10 cm H2O PEEP applied whereas a CVP above 10 mmHg -no predictive value

Fluid resuscitation initially target a CVP of at least 8 mm Hg (12 mm Hg in mechanically ventilated patients)-Level 1 C

However no threshold value of CVP that identifies patients whose CO will increase in response to fluid resuscitation.

Mixed Venous Oximetry Provides global estimation of

adequacy of oxygen delivery (DO2 ) relative to tissue needs.

SvO2 = SaO2 - (VO2/(CO x 1.34 x Hb)) If O2 sat, VO2 & Hb remain constant,

SvO2 is indirect indicator of CO Can be measured using from blood

gas from distal lumen of PA catheter Normal SvO2 ~ 65% [60-75]

↑ SvO2 [> 75%]› Wedged PAC: reflects LAP saturation› Low VO2: hypothermia, general

anesthesia, NMB› Unable to extract O2: CO poisoning› High Cardiac output: sepsis, burns, L→ R

shunt, AV fistulas

↓ SvO2 [< 60%]› Low CO: MI, CHF, hypovolemia › Low Hb : bleeding, shock› ↓ SaO2 : hypoxia, resp distress› ↑ VO2: fever, agitation, thyrotoxic,

shivering

SvO2 is a balance between oxygen consumption and oxygen delivery

›Normal: 60-80% ScvO2 (Pre-Sep) catheter is placed in superior

vena cava or right atrium

›ScvO2 is always 5-18% >SvO2 in septic shock

›Goal: ScvO2>70%

›Use just like any other central line

Presep Catheter

PA Catheter

Werner ForssmannThe Nobel Prize in Physiology or Medicine 1956

“…develop a technique for the catheterization of the heart. This he did by inserting a canula into his own antecubital vein, through which he passed a catheter for 65 cm and then walked to the X-ray department, where a photograph was taken of the catheter lying in his right auricle.” -The Nobel Foundation 1956

Pulmonary Artery Catheter The purpose of this catheter is to :

Evaluate the hemodynamic treatments and measure the patient’s hemodynamic status

Indirectly measures the LAP by wedging a catheter into a small pulmonary artery tightly enough to block flow from behind and thus to sample the pressure beyond. (PCWP : 5-12mm Hg)

Draw mixed venous blood samples Obtain central vascular pressures measurements Evaluation of cardiac output in complex medical

situations Prophylactic insertion for high-risk surgeries

“Floating a Swan”

Cardiac Output Monitoring

Cardiac Output Monitoring Fick Method (ADOLF FICK in 1870)

› Amount of oxygen picked up by the blood as it passes through the lungs must be equal to the amount of oxygen taken up by the patients lungs during respiration

› Concept that oxygen consumption = oxygen extraction by the tissues per unit time from the circulation

› O2 Extracted (VO2) = (CaO2 - CvO2) x CO

› CO = VO2/(CaO2-CvO2)

Cardiac Output Monitoring Indicator Dilution

› Dye Dilution› Thermodilution

Current Method Of Choice inert indicator without drawing of blood cold injectate into RA with resulting temp change detected at PA thermistor

modified Stewart-Hamilton equation solved by computer (area under temp versus time curve)

CO is inversely proportional to area under the curve

Pulmonary Artery Pressure Monitoring Contraindications

AbsoluteTricuspid or Pulmonary valve stenosis

RA or RV massesTetralogy of Fallot

RelativeSevere arrhythmiasCoagulopathyNewly inserted pacemaker wires

Complications of PAC Placement

Arrhythmias, complete heart block Valvular damage Catheter knotting and entrapment Endobronchial hemorrhage Pulmonary infarction Thrombocytopenia, thrombus

formation Incorrect placement, balloon rupture

Clinical management involving the early use of

PAC in patients with shock, ARDS or both

did not significantly affect

morbidity and mortality.

JAMA 2003; 290:2717-2720

Conclusion

PAC is a classical tool for hemodynamic assessment since it enables continuous monitoring of numerous hemodynamic parameters such as tissue oxygenation variables and estimates of cardiac filling pressures that are not provided by other monitoring devices.

A large recently published metaanalysis of RCT demonstrated that its use does not cause harm to critically ill patients.

(Shah et al JAMA. 2005;294: 1664-1670)

The heterogeneous results should be interpreted in light of the specific interventions tested, the delay for inclusion and the case mixed of the patients, and not of the choice of PAC per se as a monitoring tool

Bedside Echocardiography vs PAC in ICU

TEE produced a change in therapy in at least one third of ICU patients, independent of the presence of a PAC

Study by Benjamin et al. TEE was performed in 12 ±7 mins vs. ≥ 30 mins for PAC insertion

Bedside echocardiography has a better safety profile

PAC continuous monitoring technique to assess the response to a therapeutic intervention

Pulse Waveform Methods Advantages

Less-Invasive Than Thermodilution Real Time/ Repetitive Monitoring Disadvantages

Needs Recalibration Dependent on Compliance of Arterial Tree Little Validation in Patients with Shock

The PiCCO Technology is a combination of 2 techniques for advanced hemodynamic and volumetric management without the necessity of a pulmonary artery catheter in most patients:

a. Transpulmonary thermodilution b. Arterial pulse contour analysis

t

-∆T

t

-∆T

PICCO (Pulsion)

Transpulmonary thermodilution measurement simply requires the central venous injection of a cold (<8°C) or room-tempered (<24°C) saline bolus…

After which, the thermistor in the tip of the arterial catheter measures the temperature changes

The cardiac output is calculated by analysis of the thermodilution curve using a modified Stewart-Hamilton algorithm

Injection

t

-Tb

CV Bolus Injection

PiCCO Catheter e.g. in femoral artery

Parameters calculated include

via intermittent transpulmonary thermodilution

Transpulmonary cardiac output (C.O.) Intrathoracic blood volume (ITBV) Global end diastolic volume (GEDV) Extravascular lung water (EVLW) Cardiac function index (CFI)

Global Enddiastolic Volume (GEDV) is the volume of blood contained in the 4 chambers of the heart.

Global End diastolic Blood Volume GEDV: 680 – 800 ml/m2

Intrathoracic Blood Volume (ITBV) is the volume of the 4 chambers of the heart + the blood volume in the pulmonary vessels.

Intrathoracic Blood Volume Index ITBI: 850 – 1000 ml/m2

Extravascular Lung Water (EVLW) is the amount of water content in the lungs. ( Normal : 3 – 7 ml/kg)

It allows bedside quantification of the degree of pulmonary edema.EVLW has shown to have a clear correlation to severity of ARDS, length of ventilation days, ICU-stay and mortality and shown to be superior to assessment of lung edema by CXR.

Intrathoracic Blood Volume (ITBV) and Global End diastolic Volume (GEDV) have shown to be far more sensitive and specific to cardiac preload than the standard cardiac filling pressures CVP + PCWP but also than right ventricular end diastolic volume.

The striking advantage of ITBV and GEDV is that they are not wrongly influenced by mechanical ventilation and give correct information on the preload status under any condition.

via continuous 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)

calculated as (MAP- CVP) / CO

LIDCO Principle - Lithium hemodilution cardiac output Lithium dilution curve with arterial wave form

analysis calibrated with lithium dilution Injectate is an isotonic solution of lithium chloride

0.15 -0.30 mmol for an average adult Arterial pulse power analysis which estimates

stroke volume & flow Invasive Continuous CO data Peripheral or Central venous line for injectate (No

PA catheter needed) Peripheral arterial line needed to attach

sampling probe

LiDCO

Cardiac Output = (Lithium Dose x 60)/(Area x (1-PCV))

LiDCO not indicated in….

Patients on lithium therapy Patients on muscle relaxants

(atracurium) Weight < 40 kgs First trimester of pregnancy period Renal dysfunction or dialysis

(NICO) Non Invasive CO Monitor

Principle : Indirect FICK calculation with partial CO2 rebreathing technique

Uses CO2 production and difference in CO2 tension from normal respiration and re-breathing to calculate CO

No intravascular access needed

Requires endotracheal intubation Most accurate with stable respiratory

and metabolic rate Completely non invasive Placement of NICO sensor between

endotracheal tube & breathing circuit Y piece

NICO

Information Obtained from NICO CO/CI SV Pulm capill blood

flow ETCO2 Inspired CO2 RR SpO2 HR

PEEP Mean airway

pressure PIP Minute volume Dynamic

compliance Airway resistance

Advantages of NICO

Non invasive No risks of infection Automated & continuous Not technique dependent Proven accuracy Extremely simple to set up & use Cost effective

Blood Lactate Levels

Sepsis is accompanied by hypermetabolic state, with enhanced glycolysis and hyperlactataemia -not due to hypoxia

Marker of tissue perfusion and adequacy of resuscitation

Blood lactate concentration in excess of 4 mmol /L: is associated with a high risk of mortality

Clinical Implications

Appropriate to use elevated lactate trigger to initiate aggressive care-Level 1C› In the event of hypotension and/or lactate

> 4 mmol/l (36 mg/dl):–initial minimum of 20 ml/kg of crystalloid (or colloid equivalent)

› Apply vasopressors for hypotension not responding to initial fluid resuscitation to maintain MAP >65 mmHg

Conclusions A knowledge deficit disorder continues to

exist in ICU regarding ideal hemodynamic monitoring

Major problem is the user not the device of monitoring

Not everything that counts can be counted;

And not everything that can be counted

counts -ALBERT EINSTEIN

Thank You