Hemodynamic Monitoring

Hemodynamic monitoring Introduction Critically ill patients require continuous assessment of their cardiovascular system to diagnose and manage their complex medical conditions. This is most commonly achieved by the use of direct pressure monitoring systems, often referred to as hemodynamic monitoring. Heart function is the main focus of hemodynamic studies. Hemodynamic pressure monitoring provides information about blood volume, fluid balance and how well the heart is pumping. Nurses are responsible for the collection, measurement and interpretation of these dynamic patient status parameters. Hemodynamic are the forces which Circulates blood through the body. Specifically, hemodynamic is the term used to describe the intravascular pressure and flow that occurs when the heart muscle contracts and pumps blood throughout the body. Definition Hemodynamic monitoring is the measurement and interpretation of biological systems that describes the performance of cardiovascular system. Purposes • • • Early detection, Identification and treatment of life-threatening conditions such as heart failure and cardiac tamponade. Evaluate the patient's immediate responses to treatment such as drugs and mechanical Support. Evaluate the effectiveness of cardiovascular functions such as cardiac output and index. Indications • • Any deficits or loss of cardiac function: such as myocardial infarction, cardiomyopathy congestive heart failure All types of shock: Cardiogenic shock, Anaphylactic shocks neurogenic shock • Decreased urine output from dehydration, haemorrhage, GI bleed, burns or surgery. TYPES (a) Non-Invasive hemodynamic monitoring. Temperature monitoring Respiratory rate Heart rate monitoring. Arterial blood pressure monitoring Capillary Refill time Pulse oximetry/ Tissue oxygenation Spo2 (b) Invasive hemodynamic monitoring venous pressure monitoring: JVP & CVP Pulmonary artery pressure monitoring. Cardiac output Arteriovenous gas analysis Non- invasive hemodynamic monitoring Temperature monitoring Indications Fever Hyperthermia Heatstroke Hypothermia Frostbite Heat exhaustion Assessment of hemodynamic status Routes Oral Axilla Rectum Tympanic membrane Skin Temporal artery Acceptable range for adult Sites Temperature range Oral/ tympanic 36-38 degree Celsius (96.8-98.6 degree Fahrenheit) Axillary 36.5 (97.7) Rectal 37 (98.6) Tympanic 37.5 (37.5) Temperature monitoring devices Electronic thermometer Tympanic membrane thermometer Temporal artery thermometer Digital thermometer Infrared thermometer chemical dot thermometer PULSE RATE Factors influencing pulse rate Factors Increase pulse rate Decrease pulse rate Exercise Short term exercise Long term exercise Temperature Hyperthermia Hypothermia Emotion Acute pain, anxiety Unrelieved pain, relaxation Drug Positive chronotropic Negative chronotropic Haemorrhage Loss of blood Postural changes Standing or sitting Pulmonary conditions Asthma, COPD Lying down Pulse points on the body Methods of assessing pulse Palpation Auscultation ECG Spo2 probe Characters of pulse Rate Rhythm Strength Equality Force Tension Form Patterns of pulse Dicrotic pulse Pulses alternans Pulses bigeminies Pulses bisferiens Pulses tardus et parvus Pulses paradoxus Respiration Factors influencing character of respiration Exercise Acute pain Anxiety Smoking Body position Medication Neurological injury Haemoglobin function Methods of assessing respiration Characteristics of respiration Rate Depth Rhythm Alteration in breathing pattern Bradypnea Tachypnoea Apnoea Hyperventilation Hypoventilation Cheyne stokes respiration Kussmaul’s respiration Biot’s respiration Paradoxical respiration Pulse oximetry It is used to detect sudden changes in saturation of oxygen. Unreliable the value when ; Cardiac arrest Shock Sepsis Sites of placing probe Mechanism It works on the principle of spectrometry Factors influencing determination of spo2 Interference with light transmission • • • • • • • Outside light sources Carbon monoxide Patient motion Jaundice Intravascular dyes Nail polish, artificial nails Dark skin pigment Inference with arterial pulsation • • • • Peripheral vascular disease Hypotension Vasoconstrictors Peripheral oedema Blood pressure monitoring Indications Screening geriatric patients Screening all hospitalized patients as part of minimum baseline data Maintaining patients receiving cardiac medication Monitoring patients with known risk factors (e.g., renal disease, hyperthyroidism, retinal detachment) Monitoring intensive care patients Assessing emergency cases (e.g., trauma, diabetic ketoacidosis, pericardial effusion) Perioperative monitoring Postoperative monitoring Therapeutic monitoring of patients on cardiac medication Therapeutic assessment in patients with hypertension Factors influencing blood pressure Age Stress Ethnicity Gender Daily variation Medication Activity Weight Smoking Types of BP monitors Blood pressure cuff size and position Width: 40% of upper arm circumference Length: 80% of upper arm circumferences Positions for measuring blood pressure Sites for measuring BP Consequences of common errors and artifacts Error or artifact Consequence Cuff too wide Falsely low bleeding Cuff too small or narrow Falsely high reading Cuff too loose Falsely elevated reading Cuff over a joint Less likely to compress artery Hole in cuff Pressure leaks too fast to reliably record Cardiac arrhythmia Erratic reading Heavy respiration Can be mistaken for flow with doppler Motion Interferes with obtaining a doppler signal and oscillometer devices Blood pressure categories Blood classification SBP (mmhg) DBP(mmhg) Normal <120 <180 Pre-hypertension 120-139 80-90 Stage 1 140-159 90-99 Stage 2 >160 >100 Capillary refill test The Capillary refill test (CRT) is a rapid test used for assessing the blood flow through peripheral tissues. It's a quick test performed on the nail beds to monitor the amount of blood flow to tissues and dehydration. [1] The CRT measures the efficacity of the vascular system of hands and feet as they are far from the heart. Electrocardiogram Electrocardiography is the process of producing an electrocardiogram (ECG or EKG), a recording of the heart's electrical activity through repeated cardiac cycles. It is an electrogram of the heart which is a graph of voltage versus time of the electrical activity of the heart using electrodes placed on the skin. These electrodes detect the small electrical changes that are a consequence of cardiac muscle depolarization followed by repolarization during each cardiac cycle (heartbeat). Changes in the normal ECG pattern occur in numerous cardiac abnormalities, including cardiac rhythm disturbances (such as atrial fibrillation and ventricular tachycardia), inadequate coronary artery blood flow (such as myocardial ischemia and myocardial infarction), and electrolyte disturbances (such as hypokalaemia and hyperkalaemia]). Normal sinus rhythm Sinus bradycardia Sinus tachycardia Atrial fibrillation Atrial flutter Ventricular tachycardia Ventricular fibrillation Electrolyte imbalance ECG changes Hypocalcaemia Prolonged QT interval Prolonged ST interval Shortened ST segment Widened T wave ST depression Shallow, flat, or inverted T wave Prominent U wave Tall peaked T wave Flat P waves Widened QRS complex Prolonged PR interval Tall T waves Depressed ST segment Prolonged PR interval Widened QRS complex Hypercalcemia Hypokalaemia Hyperkalaemia Hypomagnesemia Hypermagnesemia INVASIVE HEMODYNAMIC MONITORING Central venous pressure (CVP) Normal range- 5-10 cm H2O, 2-6 mm Hg The central venous pressure (CVP) is the pressure measured in the central veins close to the heart. It is the pressure measured at the junction of the superior vena cava and the right atrium. And no valve in between. It indicates mean right atrial pressure and is frequently used as an estimate of right ventricular preload. It reflects the driving force for filling of the right atrium & ventricle It indicates the relationship of blood volume to the capacity of the venous system. Right-sided cardiac function is assessed through the evaluation of the CVP. Left-sided heart function is less accurately reflected by the evaluation of CVP but may be useful in assessing chronic right and left heart failure and/or differentiating right and left ventricular infarctions. Requires the threading of a catheter into a large central vein (subclavian, internal/external jugular. median basilic, or femoral). The catheter tip then is positioned in the right atrium, upper portion of the superior vena cava or the inferior vena cava (femoral approach only). Purposes of CVP monitoring include a. To serve as a guide for fluid replacement b. To monitor pressures in the right atrium and central veins c. To administer blood products, total parenteral nutrition, and drug therapy contraindicated for peripheral infusion d. To obtain venous access when peripheral vein sites are inadequate e. To insert a temporary pacemaker f. To obtain central venous blood samples INDICATIONS Major operative procedures involving large fluid shifts or blood loss Intravascular volume assessment when urine output is not reliable or unavailable Temporary Haemodialysis Surgical procedures with a high risk for air embolism, CVP catheter may be used to aspirate intracardiac air Frequent venous blood sampling, Inadequate peripheral intravenous access Temporary pacing Venous access for vasoactive or irritating drugs & Chronic drug administration Rapid infusion of intravenous fluids (using large cannula) Total parenteral nutrition The presence of persistent hypotension despite fluid restriction Vasopressor therapy Haemorrhage Trauma sepsis Burn Heart failure Contra-indications Bleeding disorders (platelet counts <50,000, bleeding is uncommon and easily managed). Anticoagulation or thrombolytic therapy. Combative patients. Distorted local anatomy. Cellulitis, burns, severe dermatitis at site. Vasculitis. Insertion sites Methods of CVP monitoring Manometer system transducer system Interpretation of CVP values High CVP Low CVP Cardiac tamponade haemorrhage Constrictive pericarditis dehydration hypervolemia hypovolemia Right sided HF Vomiting, diarrhoea Pulmonary hypertension Decreased venous return Tricuspid stenosis and regurgitation Excessive veno or vasodilation Shock Complications Haemorrhage Catheter occlusion Infection Air embolus Catheter displacement PULMONARY ARTERY PRESSURE(PAP) MONITORING Purposes To monitor pressures in the right atrium (CVP), right ventricle, pulmonary artery, and distal branches of the pulmonary artery (PCWP). The latter reflects the level of the pressure in the left atrium (or filling pressure in the left ventricle); thus, pressures on the left side of the heart are inferred from pressure measurement obtained on the right side of the circulation. To measure cardiac output through thermodilution To obtain blood for central venous oxygen saturation To continuously monitor mixed venous oxygen saturation(svO2); available on special catheters To provide for temporary atrial/ventricular pacing and intra-arterial electrocardiography (available only on special catheters) Underlying Considerations Left atrial pressure is closely related to left ventricular end diastolic pressure (LVEDP-filling pressure of the left ventricle) and is therefore an indicator of left ventricular function. The pulmonary artery diastolic pressure (PAD) reflects the LVEDP in patients with normal lungs and mitral valve. The PAD can be continuously monitored as an approximation of LVEDP (limits excessive balloon inflation to obtain a PCWP and subsequent risk of balloon rupture). The SvO2, is affected by four factors: cardiac output, haemoglobin, arterial oxygen saturation (SaO2), and tissue oxygen consumption. Changes in SvO2, alert the clinician to changes in these factors. More rapid detection of change facilitates interventions to correct problems before significant deterioration in patient's condition occurs. If the amount of oxygen supplied to the tissues is inadequate to meet demands, more oxygen will be extracted from venous blood and the SVO₂ will decrease. If oxygen supply exceeds demand, the SvO2 will increase. Methods The Swan-Ganz catheter is a flow-directed, balloon- tipped, four to five-lumen catheter that is percutaneously inserted at the bedside and allows for continuous PAP monitoring as well as periodic measurement of PCWP and other parameters. The catheter is 110 cm long, marked at increments of 10 cm, and is available in varying diameters Most catheters in use incorporate thermodilution for determination of cardiac output. If monitoring of SvO2 is desired, a pulmonary artery catheter incorporating fiberoptics is used. If temporary cardiac pacing capability is desired, a catheter with a lumen for a pacing wire may be used. Catheter may be inserted under fluoroscopy or at the bedside using the hemodynamic wave form as a guide to correct position. Cardiac Output Cardiac output is the amount (volume) of blood ejected by the left ventricle into the aorta in 1 minute. The normal cardiac output is 4 to 8 L/min. Underlying Concepts CO=SV * HR Average HR=70bpm Average SV=70-80 ml/min Average CO= 5000 ml/min Cardiac output is determined by stroke volume (SV) and heart rate (HR). • • HR = number of cardiac contractions per minute. The integrity of the conduction system and nervous system innervation of the heart influence functioning of this determinant. SV = amount of blood ejected from ventricle per beat. The amount of blood returning to the heart (preload), venous tone, resistance imposed on the ventricle before ejection (afterload), and the integrity of the cardiac muscle (contractility) influence the functioning of this determinant. The body alters cardiac output by increases/decreases in one of both of these parameters. Cardiac output is maintained if the HR fails by an increase in SV. Likewise, a decrease in SV produces a compensatory rise in HR to keep the cardiac output normal. Cardiac output will decrease if either of the determinants cannot inversely compensate for the other. Cardiac output measurements are adjusted to patient size by calculating the cardiac index (CI). CI = cardiac output divided by body surface area (BSA); BSA is determined through standard charts based on individual height and weight. Normal CI is 2.5 to 4.0 L/min/m². factors affecting HR hormones fitness level age factors affecting CO heart rate force of contraction of heart factors affecting SV heat size fitness level contractility gender duration of contraction blood volume venous return FACTORS EFFECTING CARDIAC OUTPUT Heart rate When heart rate increases, cardiac output also increases. Any factor which changes heart rate will also changes cardiac output. Force of contraction of heart When the force of contraction of the heart increases, stroke volume will increases. Therefore cardiac output will increase. Blood volume When blood volume increases cardiac output increases. Venous return It is the quantity of blood returned from all over the body through the vein into the right atrium each minute Venous return= cardiac output Assessment of Cardiac Output Low cardiac output may be detected by: 1. Changes in mental status 2. An increase in heart rate 3. Shortness of breath 4. Cyanosis or duskiness of buccal mucosa, nailbeds, and ear lobes 5. Falling blood pressure 6. Low urine output 7. Cool, moist skin Methods Cardiac output is measured by a variety of techniques. In the clinical setting, it is usually measured by the thermodilution technique used in conjunction with a flow- directed balloon catheter. (Swan-Ganz catheter). The Swan-Ganz catheter is positioned in its final position in a branch of the pulmonary artery; it has a thermistor (external sensing device) situated 4 cm from the tip of the catheter, which measures the temperature of the blood that flows by it. Other methods include; Flick’s method Indicator or dye dilution method Inhalation or inert gases Physical methods • • • Doppler echocardiography Ballistocardiograph Cineradiographic technique Research studies 1 . Mark A Hamilton, Maurizio Cecconi, Andrew Rhodes conducted a study on A systematic review and meta-analysis on the use of pre-emptive hemodynamic intervention to improve postoperative outcomes in moderate and high-risk surgical patients. Randomized clinical trials evaluating the use of pre-emptive hemodynamic intervention to improve surgical outcome were identified using multiple methods. Electronic databases (MEDLINE, EMBASE, and the Cochrane Controlled Clinical Trials register) were screened for potential trials, reference lists of identified trials were examined, and additional sources were sought from experts and industry representatives. Identified studies that fulfilled the entry criteria were examined in full and subjected to quantifiable analysis, subgroup analysis, and sensitivity analysis where possible. There were 29 studies identified, 23 of which reported surgical complications. In total, the 29 trials involved 4805 patients with an overall mortality of 7.6%. The use of pre-emptive hemodynamic intervention significantly reduced mortality (pooled odds ratio [95% confidence interval] of 0.48 [0.33–0.78]; P= 0.0002) and surgical complications (odds ratio 0.43 [0.34–0.53]; P< 0.0001). Subgroup analysis showed significant reductions in mortality for studies using a pulmonary artery catheter, supranormal resuscitation targets, studies using cardiac index or oxygen delivery as goals, and the use of fluids and inotropes as opposed to fluids alone. By contrast, there was a significant reduction in morbidity for each of the 4 subgroups analysed. The use of a pre-emptive strategy of hemodynamic monitoring and coupled therapy reduces surgical mortality and morbidity. 2. Stefan Wagenpfeil, Daniel A Reuter conducted a study on Practice of hemodynamic monitoring and management in German, Austrian, and Swiss intensive care units: the multicentre cross-sectional ICU-Cardio Man Study. In this multicentre, 1-day (November 7, 2013, and the preceding 24 h) cross-sectional study, we retrieved data on patient monitoring from ICUs in Germany, Austria, and Switzerland by means of a web-based case report form. One hundred and sixty-one intensive care units contributed detailed information on availability of hemodynamic monitoring. In addition, detailed information on hemodynamic monitoring of 1789 patients that were treated on due date was collected, and independent factors triggering the use of extended hemodynamic monitoring were identified by multivariate analysis. Besides basic monitoring with electrocardiography (ECG), pulse oximetry, and blood pressure monitoring, the majority of patients received invasive arterial (77.9 %) and central venous catheterization (55.2 %). All over, additional extended hemodynamic monitoring for assessment of cardiac output was only performed in 12.3 % of patients, while echocardiographic examination was used in only 1.9 %. The strongest independent predictors for the use of extended hemodynamic monitoring of any kind were mechanical ventilation, the need for catecholamine therapy, and treatment backed by protocols. In 71.6 % of patients in whom extended hemodynamic monitoring was added during the study period, this extension led to changes in treatment. Extended hemodynamic monitoring, which goes beyond the measurement of blood pressures, to date plays a minor role in the surveillance of critically ill patients in German, Austrian, and Swiss ICUs. This includes also consensus-based recommended diagnostic and monitoring applications, such as echocardiography and cardiac output monitoring. Mechanical ventilation, the use of catecholamines, and treatment backed by protocol could be identified as factors independently associated with higher use of extended hemodynamic monitoring. Conclusion Hemodynamic monitoring is the repeated assessment of circulatory function over time. Perturbations in circulatory function are expected during physiologic stress such as surgery. Uncontrolled, these perturbations can lead to tissue hypoxia, ultimately resulting in perioperative morbidity and mortality. As such, hemodynamic monitoring is a fundamental component of delivering safe anaesthetic care. It is essential to note, however, that hemodynamic monitoring alone does not change anaesthetic or surgical outcomes. To improve perioperative outcomes, hemodynamic monitoring must not only be of high quality, but the measurements must also be interpreted correctly, so that the anaesthesiologist can intervene in an appropriate and timely fashion. Poor quality measurements or a misinterpretation of hemodynamic monitors will lead to incorrect therapeutic decisions resulting in adverse outcomes. 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