Basic Science Conference 1/26/2010

Background Latin word monere, which means “to warn, or advise,” is the origin for the English word monitor. Patients undergo monitoring to detect pathologic variations in physiologic parameters, in order to give us advance warning of deterioration of one or more organ systems. GOAL: Use the information to make a timely intervention. Monitoring also used to guide resuscitation and titrate medications.

Background (cont.) The ultimate goal of hemodynamic monitoring is to ensure that the flow of oxygenated blood through the microcirculation is sufficient to support aerobic metabolism at the cellular level. This involves multiple inputs. Oxygen delivery CO Hgb O2 sat PAO2

Arterial Blood Pressure The pressure exerted by blood in the systemic arterial system. Hypotension = Shock ? MAP = CO x SVR How do we measure blood pressure? Non-invasive (cuff) Invasive Risks and benefits

Noninvasive Manual and automated means, both of which use a cuff. The width of the cuff should be about 40% of the circumference. Korotkoff sounds Systolic- tapping sounds first audible Diastolic- audible pulsations disappear Dyna-map

Invasive Fluid-filled tubing to connect an intra-arterial catheter to external strain-gauge transducer which is transduced as a continuous waveform. Underdamped –systolic overestimated and diastolic underestimated Overdamped- systolic underestimated and diastolic overestimated Use Mean Arterial Pressure Systolic pressure higher, diastolic pressure lower in the radial artery compared to the aorta

Invasive Complications Thrombosis (Allen test) Air Embolism Infection

EKG monitoring Continuous monitoring with three lead EKG Immediate alarm with arrhythmias Can detect ST elevation No substitute for 12 lead EKG

Cardiac output Determinants of Cardiac Performance Preload - EDV Afterload-SVR Contractility- dependent on preload and afterload

Pulmonary artery catheter PAC has four channels Balloon (1.5cc) CVP, PA Insertion Waveforms Distance 45 cm RSCV 50cm RIJ 55cm LSC 60cm LIJ

Approximate Normal Ranges for Selected Hemodynamic Parameters in Adults CVP 0–6 mmHg Right ventricular systolic pressure 20–30 mmHg Right ventricular diastolic pressure 0–6 mmHg PAOP 6–12 mmHg Systolic arterial pressure 100–130 mmHg Diastolic arterial pressure 60–90 mmHg MAP 75–100 mmHg Q T 4–6 L/min Q T * 2.5–3.5 L·min –1 ·m –2 SV 40–80 mL SVR 800–1400 dyne·sec·cm –5 SVRI 1500–2400 dyne·sec·cm –5 ·m –2 PVR 100–150 dyne·sec·cm –5 PVRI 200–400 dyne·sec·cm –5 ·m –2

Hemodynamic measurements Cardiac output by thermodilution Mixed venous oximetry RV ejection fraction

Types of Shock Hemorrhagic Septic Cardiogenic Neurogenic Hypo adrenal

Risks and benefits of PACs Many studies show no mortality difference with PAC use and more complications related to the catheter or its placement. Alternatives Doppler Ultrasonography Impedance cardiography Pulse contour analysis TEE

Respiratory monitoring The ability to monitor various parameters of respiratory function is of utmost importance is critically ill patients. Arterial blood gases Peak and plateau airway pressure Pulse oximetry CO2 monitoring

ABG O2 (PEEP, FIO2) CO2 (RR, TV) O2 sat HCO3 BE/BD

Airway Pressures Increased pressure = decreased compliance Hemo/pneumothorax Atelectasis Pulmonary edema ARDS Abdominal distension Barotrauma

Renal monitoring Urine output Bladder pressure

Neurologic monitoring Intracranial pressure CPP= MAP- ICP CPP>60 Allows monitoring and drainage Strategies to decrease ICP Transcranial doppler ultrasonography EEG Brain tissue oxygen tension

Conclusions Physiologic monitoring provides us with a multitude of information. Determining what information is beneficial and using this to positively affect the outcome of the patient is the key.

All of the following are most often associated with a decrease in SVO2 except: Myocardial infarction Cardiac tamponade Hemorrhagic shock Septic shock

You place a swan ganz catheter in a 709kg adult male through the left subclavian vein and get a wedge pressure. The approximate distance into the patient should be: 45cm 50cm 55cm 60cm

While trying to treat a patient with severe ARDS, you start to increase the PEEP to improve oxygenation. After doing this, you notice a decrease in urine output. The mechanism of decreased urine output with increased PEEP is: Compartment syndrome Decreased cardiac output Reduced oxygenation Retained CO2

A patient stops making urine after surgery. All of te following values are consistent with pre-renal renal failure except: Urine Na 5 BUN/Cr ratio >35 FeNA=0.1% Urine osmolality 200 mOsm

All of the following concerning pulmonary artery catheters are true except: Excessive PEEP can artificially increase wedge pressure. Excessive PEEP can artificially decrease wedge pressure. Zone III of the lung is the optimal site of placement. The balloon should be inflated when advancing the catheter.

A critical care patient has the following PAC values: CI 1.8, SVR 3000, and a wedge pressure of 5. This is most consistent with: Septic shock Hypovolemic shock Cardiogenic shock Neurogenic shock

A critical care patient has the following PAC values: CI 5.0, SVR 500, and a wedge pressure of 7. This is most consistent with: Septic shock Hypovolemic shock Cardiogenic shock Neurogenic shock

A critical care patient has the following PAC values: CI 1.8, SVR 3000, and a wedge pressure of 28. This is most consistent with: Septic shock Hypovolemic shock Cardiogenic shock Neurogenic shock

A critical care patient has the following PAC values: CI 2.0, SVR 500, and a wedge pressure of 5. This is most consistent with: Septic shock Hypovolemic shock Cardiogenic shock Neurogenic shock

A patient with ARDS following an inhalation injury has an oxygenation saturation of 90% on 90% FiO2 with an SVO2 of 55. The patient’s ABG is pH 7.35, pO2 of 60, and pCO2 60. The patient has a cardiac output of 5, and a Hgb of 8. Oxygen delivery will increase the most by: Increasing cardiac output by 1 Increasing hemoglobin by 2 Increasing FiO2 by 10% Decreasing CO2 by 10% Oxygen delivery = CO x[(Hgb x1.34x O2 sat) + (0.003x PaO2)]