MedSurg II - Hemodynamics

olanjones's version from 2017-04-06 15:51

Terms & Manangment

Question Answer
Hemodynamic monitoringMeasurements of pressure, flow, & oxygenation w/in the cardiovascular system
Cardiac Indexmeasurement of the CO adjusted for body surface area (more precise measurement of efficiency of heart’s pumping action than CO alone)
Measurement TypesSystemic & pulmonary artery pressures (PA); Central venous pressure (CVP); Pulmonary artery wedge pressure (PAWP); Cardiac output (CO); Cardiac index (CI); Oxygen saturation
Purposeassess heart function, fluid balance, & effect of fluids/drugs on cardiac output
How is Preload measuredR ventricle – CVP; L ventricle – PAWP
Preload is the ability of the muscle fiber to stretch during end diastole
How is Afterload indexedSVR & arterial pressure indicate left ventricular afterload; PVR & pulmonary arterial pressure indicate right ventricular afterload
Contractility* ↑using positive inotropes (vasoactive drugs, calcium, milrinone)
* ↓using negative inotropes (alcohol, CCB,β-blockers) and acidosis
Vasoactive drugsdobutamine, dopamine, norepinephrine, epinephrine
Dobutaminesynthetic catecholamine w/ predominantly β1-adrenergic effects (also produces some β2 stimulation, resulting in a mild vasodilation)
Dopaminechemical precursor of norepinephrine w/ both α- & β-receptor stimulation, activates dopaminergic receptors in the renal & mesenteric blood vessels
ReferencingPositioning the transducer so that the zero reference point is at level of the atria of the heart
LevophedNorepinephrine -stimulates β & α receptors, but lacks β2 effects of epinephrine
(at ↓infusion rates, β1-receptors are activated & produce ↑contractility, augmenting cardiac output; at ↑doses, inotropic effects are limited by marked vasoconstriction mediated by α-receptors)
Phlebostatic axisLandmark used to identify level of the atria in the supine patient; Intersection of 4th ICS & ½ AP diameter (mark the chest w/ felt pen)
How is the system zeroedStopcock is opened to room air & off to the patient (Zeroing confirms that when pressure w/in the system is zero, the monitor reads zero)
Square Wave testDetermines ability of transducer to correctly reflect pressures (done at beginning of each shift & prn when system is opened to air or accuracy is questioned)
Nursing Management-Obtain baseline data & monitor for changes (general appearance, LOC, skin color/temp, VS, peripheral pulses, cap refill, & UO)
-Always correlate observational data w/ data obtained from biotechnology (single hemodynamic values are rarely helpful)
-Monitor trends in values & evaluate whole clinical picture w/ goal of recognizing early clues & intervening before problems escalate

Resting Parameters

Question Answer
CVP (preload)2-8 mmHg
PAWP (preload)6-12 mmHg
PADP (preload)4-12 mmHg
RVEDV (preload)
(R ventricular end-diastolic vol)
100-160 mL
PVR (afterload)<250
PVRI (afterload)160-380
SVR (afterload)800-1200
SVRI (afterload)1970-2390
MAP (afterload)70-105 mmHg
PAMP (afterload)10-20 mmHg
SV60-150 mL/min
SVI30-65 mL/beat/m2
(stroke volume variation)
HR60-100 bpm
CO4-8 L/min
CI2.2-4L/min/ m2
(R ventricular ejection fraction)
Arterial hgb O2 sat95%-100%
Mixed venous hgb O2 sat60%-80%
Venous hgb O2 sat70%

Invasive Lines

Question Answer
Arterial catheters (AC)-Used to closely monitor BP, Monitor effectiveness of vasoactive meds, Blood sampling
-Contraindications: significant coagulopathies, thrombolytic therapy, specific site contraindications (scar tissue, vascular anomalies)
-Inserted in radial, ulnar, or femoral artery
Nurses’ responsibility for arterial catheter insertionPrepare pressurize saline bag, get the transducer ready, and get the kit for the arterial catheter placement
AC ComplicationsHemorrhage if line is dislodged, hematoma, infection at insertion site, end circulatory impairment of the hand (also air embolism, nerve damage, compromised blood flow)
TransducerConverts physiologic events into electrical signals (e.g., pressure, temperature, light)
AmplifierPicks up electrical signal and transmits to display through cable
Monitor displayDisplay readings (waveforms, pressure values)
Catheter tubing & flush systemKeep catheter patent; Flush solution 3ml/hr (check protocol re: heparin in solution); Pressure bag (w/out pressurization bag would fill w/ blood)
General care & precautions-Hand washing, Sterile technique on insertion, Meticulous maintenance per hospital policy
-Cont. monitor PA pressure waveform to detect spontaneous wedging, Ensure monitor alarms are on, Monitor for air in tubing
-Label & change flush bag/tubing/dressing per hospital policy/procedure, Maintain pressure bad at 300 mmHg
Swan-Ganz catheter (pulmonary artery cath)-110 cm long w/ multiple lumens; distal lumen port is w/in pulmonary artery; balloon surrounding the distal lumen port allows for PAWP measurement
-Contraindications: coagulopathy, endocardial pacemaker, endocarditis, mechanical tricuspid/pulmonic valve
-Inserted into internal jugular, subclavian, antecubital, or femoral vein (advanced through R side of heart)
What is the purpose of the balloon in the PA1. to allow moving blood to float the catheter forward
2. to allow PAWP measurement
Why monitor PA pressureFluid therapy based on PA pressures can restore fluid balance while avoiding overcorrection/undercorrection of the problem
Monitoring PA pressures permits precise therapeutic manipulation of preload, allowing CO to be maintained w/out placing pt at risk for pulmonary edema
Nurses’ responsibility for PA catheter insertionSet up a pressurized bag, transducer, & the PA catheter kit; Position the patient flat; Nurse will monitor the waveforms as catheter is advanced through the heart
PA ComplicationsDysrhythmias may occur as catheter travels through heart (watch EKG!)

Circulatory Assist Devices

Question Answer
CADs provide support when1. L/R/both ventricles require support while recovering from acute injury
2. Pt must be stabilized before surgical repair of the heart
3. Heart has failed, & pt is awaiting cardiac transplant
*ALL CADs ↓cardiac workload, ↑myocardial perfusion, augment circulation*
Intra-aortic balloon pump (IABP)Provides temporary circulatory assistance by reducing afterload & augmenting the aortic diastolic pressure, resulting in improved coronary blood flow (inserted through femoral artery, sits just below aortic arch)
How does IABP workUses counter pulsation - machine inflates/deflates the balloon w/helium at start of diastole & deflates just before the next systole; When balloon inflates blood is forcibly displaced distal to the extremities and proximal to the coronary arteries; Diastolic arterial pressure rises ↑coronary artery perfusion & perfusion of vital organs
IABP ComplicationsVascular injuries such as dislodgement of plaque, aortic dissection, & compromised distal circulation; Balloon can destroy platelets causing thrombocytopenia or can block other arteries (e.g. renal artery)
Positioning for IABP patientRelatively immobile, limited to side-lying or supine position, HOB cannot be raised more than 45° (these patients are critically ill & will probably be intubated/ventilated)
Timing of IABP1:1 w/ the heart rate initially but as the patient improves ratio can change to 1:2 & then 1:3. (Initially will be the only patient a nurse is assigned, as the patient improves the nursing ratio will be 1:2)
IABP ContraindicationsIrreversible brain damage, Major coagulopathy (DIC), Terminal/untreatable disease of major organ system, AA or thoracic aneurysms, Mod-severe aortic insufficiency, Generalized PVD
Ventricular assist device (VAD)Temporary device that supports circulation; Shunts blood from L atrium or ventricle to the device & then the aorta; May be implanted internally or attached to external device
Primary indicator for VAD supportFailure to wean from cardiopulmonary bypass after surgery (are also used in patients w/ L ventricular failure caused by MI or patients awaiting heart transplants)
VAD Nursing care-Similar to IABP; Observe for bleeding, cardiac tamponade, ventricular failure, infection, dysrhythmias, renal failure, hemolysis, thromboembolism
-VAD may be mobile/require activity plan (some pts may go home)
-D/C teaching (in depth) about the device & support equipment(battery chargers, etc); A competent caregiver must be present at all times

Managing IABP Complication

Question Answer
Infection from invasive lineStrict aseptic technique for insertion & dressing change, Use occlusive dressings, Admin prophy Abx
Pneumonia (d/t immobilization)Reposition q 2H, watch ECG for artifact if performing chest physiotherapy
Arterial trauma-Eval & mark peripheral pulses prior to insertion to use as baseline; After insertion eval perfusion in extremities at least q 1H
-Measure UO q 1H (occlusion of renal artery ↓UO)
-Observe arterial waveforms for sudden changes
-Keep HOB no higher than 45
-Do not flex cannulated leg at hip; Immobilize leg to prevent flexion using draw sheet tuck under mattress, soft restraint, or knee immobilizer
Thromboembolism-Admin prophy heparin if ordered
-Eval pulses, UO, LOC at least q 1H
-Check circulation, sensation, movement in both legs q hour
Hematological complicationsMonitor coagulation profiles, H&H, platelet count (thrombocytopenia caused by platelet aggregation along balloon)
Hemorrhage from insertion siteCheck for bleeding at least q 1H, Monitor VS, signs of hypovolemia w/ each check
Balloon leak/rupturePrepare for emergent removal & possible reinsertion

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