Therapeutic interventions (CMC) Flashcards
describe echocardiography, a cardiac diagnostic procedure
US waves to create images of heart allowing for evaluation of cardiac structures and function
describe cardiac catheterization, a cardiac diagnostic procedure.
what does it help identify?
catheter inserted into blood vessel and guided to the heart to measure pressures, obtain blood samples, or inject contrast dye for angiography.
-helps identify CAD, heart valve issues, congenital heart defects
all on one card bc it is our bread and butter
describe the diagnostic procedure of a right heart catherization
- how performed
- blood samples
- evaluates
- risk
1. used to assess
aka pulmonary artery catheterization.
used to assess the hemodynamics of the right side of the heart and pulmonary circulation. (specifically measure pressure in RA (CVP), RV (RVP), PA (PAP), and PCWP which reflects LA pressure.
involves the insertion of a catheter into a vein, typically IJ, subclavian, or femoral vein, and advancing it through the RA and RV into PA. typically local anesthesia with sedation. using fluoroscopic guidance to ensure placement.
blood samples can be obtained for oxygen saturation analysis to deterine the presence of shunts or to quantify cardiac output using thermodilution or Fick’s principle.
evaluates cardiac function (CO, vascular resistance, fluid status) and dx heart failure, pHTN, and congenital heart defects
risks: arrhthymias, bleeding at insertion site, infection, pneumothorax, PA rupture or thrombosis
describe the diagnostic procedure: left heart catheterization
used to dx and manage:
used to evaluate the function and strucutre of the left side of the heart, including the left atrium, left ventricle, aortic valve, and coronary arteries.
dx and manage cardiac conditions: CAD, valvular heart disease, cardiomyopathies
how is a left heart cath performed?
-pressure that are measured, what they show
-complications
-local anesthesia and fluoroscopic guidance
-artery is accessed (usually fem or radial), advanced into aorta and then LV
-typically involves angiography to visualize coronary arteries on xray using contrast dye (assess stenosis, occlusions, or abnormalities)
-LV pressure and CO can be measured (and other pressures); provide insight into aortic stenosis and mitral regurgitation
-left ventriculography: evaluates LV function, wall motion abnormalities, and ejection fraction
-complications: bleeding at access site, vascular injury, arrhythmias, or contract-induced nephropathy
primary goal of PCI
restore adequate blood flow to the heart by mechanically widening the obstructed artery, typically through balloon angioplasty, where small balloon is inflated at site of blockage, compressing the plaque against the arterial wall. Usually a stent is placed to keep artery open and prevent re-narrowing
what cardiac condition does a PCI treat/manage
CAD
describe PCI procedure
begins with cardiac cath, inserted into fem or radial artery, guided to coronary arteries under fluoro
-contrast day injected to visualize blockages via angiography
-interventional cardiologists decide on technique: simple balloon angioplasty or stent placement
types of stents for PCI
bare metal or drug eluding (DES)
drug eluding: coasted with medication that helps prevennt restenosis by inhibiting cell proliferation at the stent site.
factors to decide: risk of bleeding, likelihdoof of restonsis.
PCI risks
bleeding at cath site, arterial damage, kidney injury from constrast dye, heart attack or stroke.
long term: in-stent restonsis and stent thrombosis, needing dual antiplatelet therapy post procedure
what is a pericardiocentesis?
procedure involving aspiration of fluid form pericardial sac (double walled sac containing the heart). Primarily performed to relieve cardiac tamponade. The fluid’s characteristics can be tested to dx underlying conditions.
key indications for pericardiocentesis
and contraindications
hemodynamic instability due to cardiac tamponade, large symptomatic pericardial effusion, diagnostic evaluation of unexplained pericardial effusion,
contra: uncorrected coagulopathy, small effusions without clinical symptoms
complications from pericardiocentesis
myocardial puncture, coronary artery injury, arrythmias, infection
What is an IABP?
catheter-based device that is inserted into the aorta, typically through the femoral artery, to support cardiac function and improve myocardial oxygen delivery in patients with severe cardiac conditions. It has a long, thin tube with a balloon at its distal end.
the primary function is to augment diastolic blood pressure and decrease afterload, enhancing coronary perfusion and reducing myocardial oxygen demand.
How does the IABP work?
counterpulsation. during diastole, balloon inflates, increasing aortic pressure and improving blood flow to coronary arteries. occurs just after the closure of the aortic valve, optimizing coronary perfusion when the heart muscle itself receives its blood supply. during systole, the balloon deflates rapidly, creating a vacuum effect that decreases resistance in the aorta. the reduction in afterload makes ventricular ejection easier and decreases myocardial workload.
indications for IABP
contraindications
cardiogenic shock
acute MI with complications like MR or VSD
unstable angina refractory to medical therapy
bridge to PCI or surgery
hemodynamic support in high risk cardiac surgery patients
contraindications: severe PVD, aortic dissection
potential complications of IABP
limb ischemia
bleeding at insertion site
infection
balloon rupture
kidney injury
what is a LVAD?
mechanical pump that is surgically implanted to support heart function and blood flow in individuals with severe heart failure. It assists the LV by taking over its pumping action. it draws blood from the LV and delivers it directly into the aorta.
consists of several components: a pump implanted in the chest, external controller, and a power source (connect via driveline)
used as a bridge to transplantation, as destination therapy who are not heart transplant candidates, or as bridge to recovery in cases where myocardial function might improve.
anticoagulation therapy critical to minimize thromboembolic events due to non-pulsatile nature of most LVADs
describe TAVR (Transcatheter Aortic Valve Replacement)
common percutaneous intervention used to treat severe aortic stenosis. a bioprosthetic valve is delivered via a catheter through the femoral artery or another access point and deployed within the diseased aortic valve, replacing it without removing the old valve.
beneficial for those who are considered high risk for conventional surgery
describe the MitraClip procedure
for patients with MR who are not candidates for surgical repair or replacement. it is a device delivered through a transseptal approach the femoral vein to the left atrium where it clips together a portion of the mitral valve leaflets to reduce regurgitation
what is used to seal ASD and PFOs?
a septal occluder via a percutaneous catheter
what is peripheral angiography?
diagnostic procedure used to visualize the blood vessels outside of the heart to identify blockages or abnormalities in the peripheral arteries (which can lead to PAD). contrast dye is injected into the bloodstream and xrays are taken to provide detailed images of the blood vessels.
interventions following peripheral angiography
angioplasty: small balloon inserted and inflated at side of blockage to widen the vessel. most times a stent is placed to keep open
atherectomy- removing plaque from artery using rotating blade or laser. useful for calcified lesions resistant to balloon angioplasty alone.
complications of peripheral angiography and its interventions
bleeding, infection, allergic reaction to contrast dye, vessel damage or embolism
describe carotid angiography
diagnostic procedure used to visualize the carotid arteries, which supply blood to the brain. contrast dye is injected through a catheter into the carotid arteries, xrays are taken to reveal blockages or narrowing. used to assess presence and severity of carotid artery disease (often caused by atherosclerosis) which can lead to strokes.
interventions post carotid angiography
carotid endarterectomy (CEA): plaque removed from the arterial walls to restore normal blood. standard treatment for patients with significant stenosis, esp symptomatic or had TIAs or minor strokes.
carotid artery stenting (CAS): less invasive, small mesh tube (stent) is placed inside the artery to keep it open. often recommended to high risk surgery patients. balloon catheter expands the narrowed section of the artery before placing the stent.
both aim to prevent future strokes by improving cerebral blood flow
what is an endovascular graft?
aka endografts, medical devices used in minimally invasive treatment of vascular diseases, particularly aneurysms. designed to reinforce the weakened sections of blood vessels, most commonly within the aorta, by creating a new pathway for blood flow. crucial in preventing aneurysm rupture.
what is the procedure involving endovascular grafts?
endovascular aneurysm repair (EVAR). synthetic tube like graft is delivered to the site through catheter inserted via a small incision in femoral artery. graft is expanded and anchored in place using metallic stents, excluding aneurysm from circulation and reducing pressure on the weakened vessel wall.
size, location, vessel tortuosity and neck length are factors to consider
potential complications: graft migration or endoleaks (situations where blood leaks into aneurysm sac outside the graft)
What is a catheter-directed thrombolysis (CDT)?
minimally invasive procedure used to dissolve blood clots in the vascular system (DVT, PE). catheter is inserted into the clot allowing for localized delivery of thrombolytic agents like tissue plasminogen activator (tPA) which breaks down the fibrin matrix of the clot
catheter is navigated through vasculature until reaches site of clot. imaging techniques such as venography or angiography are used to confirm catheter placement and assess extent of thrombus. thrombolytic agent is then infused directly into the clot over a period ranging from several hours to days, depending on the size and location of the thrombus.
CDT advantages
reduced risk of bleeding complications and increased efficacy (higher local concentrations of thrombolytic drug). beneficial for those with extensive DVT or massive PE, where rapid clot resolution is necessary to restore venous patency and improve hemodynamics
CDT indications
contraindications
those with severe symptoms, contraindications to AC alone, or high risk for post-thrombotic syndrome
contra: active bleeding, recent surgery, significant coagulopathy
complications of CDT
rare but
bleeding at puncture site, hematoma formation
embolization of clot fragments
how many classes of antidysrhythmics are there?
four
- sodium channel blockers
- beta blockers
- potassium channel blockers
- calcium channel blockers
MOA of Class 1 antiarrhythmic
(sodium channel blockers) slow down depolarization phase of cardiac action potential by blocking sodium channels.
broken down into three subclasses
MOA Class 2 antiarrhythmic
Beta Blockers
reduce sympathetic nervous system stimulation of the heart by blocking beta-adrenergic receptors. this leads to decreased heart rate and contractility, which is useful in treating tachyarrhythmias.
metoprolol, atenolol
3 subclasses of antiarrhythmics
Class 1A: moderate sodium channel blockers, prolonging repolarization (Quinidine, Procainamide)
Class 1B: weak sodium channel blockage, shortening repolarization. (Lidocaine, Mexiletine)
Class 1C: strong sodium channel blockade with minimal effect on repolarization (Flexainide, Propafenone)
MOA Class 3 antiarrhythmics
potassium channel blockers
prolong repolarization by blocking potassium channels, extending the refractory period of cardiac cells. Effective in treating both atrial and ventricular dysrhythmias.
amiodarone and sotalol
MOA Class 4 antiarrhythmics
calcium channel blockers
inhibit calcium ion influx through L-type calcium channels, primarily affecting AV node conduction and reducing heart rate
Verapamil and diltiazem commonly used for rate control afib.
two main types of anticoagulants
oral and parenteral
oral AC examples and MOA
- vitamin K antagonists (warfarin)
-DOACs (dabigatran, rivaroxaban, apixaban, endoxaban)
how does warfarin work?
inhibits vitamin K epoxide reductase, an enzyme necessary for the synthesis of clotting factors II, VII, IX, and X
how do DOACs work?
directly on specific factors within the coagulation cascade
ex: dabigatran inhibits thrombin (factor IIa)
Rivaroxaban, apixaban, edoxaban inhibit factor Xa.
parenteral AC examples
UFH
LMWHs Iike enoxaparin)
fondaparinux
how does unfractionated heparin work (UFH)?
enhances the activity of antithrombin III, which inactivates thrombin and factor Xa.
how does LMWH work?
primarily inhibit factor Xa, with some effect on thrombin
how does fondaparinux work?
it is a synthetic pentasaccharide that specifically inhibits factor Xa
3 types of diuretics
based on site of action in the nephron
-thiazide diuretics
-loop diuretics
-potassium sparing diretics
how do thiazide diretics work?
on distal convoluted tubule to inhibit sodium reabsorption, leading to increased excretion of sodium and water
commonly used for long term management of HTN
hydrochlorothiazide
how do loop diuretics work?
target ascending limb of loop of Henle. inhibit sodium-potassium-chloride co-transporter, resulting in significant diuresis.
open used for rapid fluid removal in heart failure or pulmonary edema
furosemide, bumetanide
how do potassium sparing diuretics work?
work on collecting ducts and distal tubules to prevent potassium loss while promoting sodium excretion
beneficial for those at risk of hypokalemia or those requiring aldosterone antagonism.
spironolactone and eplerenone
why monitor renal function while pt on diuretics?
can decrease kidney perfusion
categories of inotropes
positive and negative, based on effects on myocardial contractility
how do positive inotropes work?
increase strength of heart’s contractions, enhancing CO. by increasing intracellular calcium concentrations, which are essential for muscle contraction.
common: dobutamine, dopamine, milrinone
how does dobutamine work?
primarily stimulates B1- adrenergic receptors, leading to increased myocardial contractility with minimal effects on heart rate
how does dopamine work?
dose dependent
moderate doses: stimulates B1 receptors to enhance CO
higher: also acts on alpha-adrenergic receptors, causing vasoconstriction
how does milrinone work?
phosphodiesterase inhibitor that increases cyclic adenosine monophosphate (cAMP) levels, leading to enhanced calcium influx and stronger myocardial contractions
how do negative inotropes work?
decrease myocardial contractility and often used to reduce cardiac workload in conditions such as hypertrophic cardiomyopathy or certain forms of angina
ex: BB like metop and CCB like verapamil
considerations for inotropes
prolonged use can lead to
-increased myocardial oxygen demand
-potential for arrythmias
primary MOA of platelet inhibitors in the most basic sense
blocking specific pathways that active platelets
how does aspirin work?
irreversibly inhibits the cyclooxygenase-1 (COX 1) enzyme in platelets. this prevents the formation of thromboxane A2, a potent promoter of platelet aggregation and vasoconstriction
how do P2Y12 receptor antagonists work?
block P2Y12 component of the ADP receptor on the platelet surface, preventing ADP-mediated activation and aggregation of platelets
ex: clopidrogrel, prasugrel, ticagrelor
how do glycoprotein IIb/IIIa inhibitors work?
prevent fibrinogen from binding to the glycoprotein IIb/IIIa receptor on activated platelets, inhibiting the final common pathway for platelet aggregation
ex: abciximab, eptifibatide, tirofiban
used primarily in ACS setting
indications for platelet inhibitors
-ACS
-PCI
-secondary prevention of MI or ischemic stroke
-prevention of stent thrombosis
classes of platelet inhibitors
-cox 1 inhibitors
-P2Y12 inhibitors
- glycoprotein IIb/IIIa inhibitors
what is a fibrinolytic /thrombolytic agent? how do they work?
class of drugs used to dissolve blood clots that have acutely formed in blood vessels (MI, ischemic stroke, PE)
involves conversion of plasminogen to plasmin, an enzyme that breaks down fibrin, the structural component of blood clots
most commonly used thrombolytics
alteplase, reteplase, tenecteplase
how does alteplase work?
it is a tissue plasminogen activator (tPA) that has a high affinity for fibrin-bound plasminogen, making it effective in clot-specific therapy. reduces systemic bleeding risks compared to older agents like streptokinase.
contraindications for thromoblytic therapy
recent surgery, active internal bleeding or hx of hemorrhagic stroke
vasoactive agents can be broadly categorized into
vasodilators and vasoconstrictors
how do vasodilators work (vaguely)? common meds?
relax the smooth muscle in the blood vessels, leading to vessel dilation, decreased SVR, reduced BP
-nitroglycerin, sodium nitroprusside, hydralazone
how do vasoconstrictors work (vaguely)? common meds?
increase vascular tone by stimulating alpha-adrenergic receptors or through other mechanisms that lead to vasoconstriction. result is increased SVR and BP
common: norepinephrine, epinephrine, phenylephrine
excessive vasodilation can lead to
hypotension and reflex tachycardia
excessive vasoconstriction can lead to
tissue ischemia due to reduced perfusion
components of a temporary pacemaker
external pulse generator and pacing lead
pulse generator is a battery-operated device that delivers electrical impulses to simulate cardiac contraction
pacing leads can be transvenous, epicardial, or transcutaneous
describe transvenous pacing
involves insertion of a pacing lead through a central vein, usually subclavian or internal jugular vein, into RV.
effective and low complication
where do epicardial leads go?
placed directly on heart’s surface during cardiac surgery and used postop
describe transcuteanous pacing
involves placing electrodes on the skin and used as immediate, non-invasive method for temporary pacing
indications for temporary pacemaker placement
symptomatic bradycardia, CHB, certain tachyarrhythmias that require overdrive pacing
drug induced bradycardia
procedures that compromise the heart’s conduction system
complications of temporary pacemaker placement
infection
lead displacement
failure to capture
etc
What is a permanent pacemaker?
a medical device implanted under the skin, typically near the collarbone, that helps regulate abnormal heart rhythms. it consists of a pulse generator (battery powered) and one or more leads that deliver electrical impulses to the heart. these impulses prompt the heart to maintain an adequate rate and rhythm, which is crucial for effective circulation and overall CV health.
permanent pacemakers are primarly used in patients with
bradycardia
also in certain cases of heart block
single chamber vs dual chamber pacemaker
single chamber stimulates either the atrium or the ventricle
dual: stimulates both chambers (not both ventricles)
leads typically stimlulate the right side of the heart.
potential complications with PPM
infection
lead dislodgement
device malfunction
what is cardiac resynchronization therapy (CRT)?
procedure designed to improve the heart’s efficiency and coordination by electrically stimulating the heart muscle to contract in a more synchronized manner.
invovles implantation of specialized pacemaker device, known as biventricular pacemaker, which delivers electrical impulses to both the left and right ventricles. typically includes three leads, one in RA, one in RV, and one placed via coronary sinus to stimulate the LV. by synchronizing contractions between venctricles, CRT aims to enhance CO, reduce MR, and improve overall cardiac function
who is the primary population to use CRT?
patients with HF who exhibit dyssynchronous ventricular contraction, often evidenced by wide QRS complex on ECG. this can lead to inefficient CO, worsening HF symptoms, and increased mortality.
candidates for CRT usually have the following criteria:
-moderate to severe HR
-reduced EF (typically less than 35%)
-QRS duration greater than 120 milliseconds
potential complications of CRT
lead displacement
infection
venous thrombosis
inappropriate pacing or sensing
what is an implantable cardioverter defibrillator (ICD)?
a surgically implanted device, typically place near left clavicle. consists of pulse generator and leads. pulse generator houses a battery and electronic circuitry that continuously monitors the heart’s electrical activity. the leads (insulated wires) extend from pulse generator into the heart chambers. dual purpose: sensing cardiac electrical activity and delivering therapeutic shocks or pacing pulses
designed to monitor heart rhythms and deliver life-saving therapy in event of life-threatening arrhythmias, such as VT or VF. critical in preventing sudden cardiac death in patients with hx of cardiac arrest or those at high risk of developing malignant arrhythmias.
how can a ICD respond to an abnormal rhythm?
based on slow vs fast
-for slower arrhythmias: may deliver anti-tachycardia pacing (ATP) which involves rapid pacing to interrupt the arrhythmia.
for dangerous rhythms like VF, delivers high energy shock to restore normal rhythm
ICDs have evolved to have additional features such as
biventricular pacing for HF management (CRT) or remote monitoring capabilities that allow real-time data transmission to healthcare providers
what is an external wearable defibrillator?
portable device designed to continuously monitor patient’s heart rhythm and deliver shock of life-threatening arryhythmias occur.
consists of three main components: a vest that contains electrodes, a monitor/defibrillator unit, a battery pack. the vest is equipped with electrodes that both monitor the heart’s electrical activity and deliver defibrillation shocks when necessary.
if arrhythmia is detected, device alerts the patient with audible and visual alarms before delivering a shock, allowing the patient to stop the treatment if they are conscious and do not require intervention.
who are external wearable defibrillators especially beneficial for?
those who are at high risk of sudden cardiac arrest but are not immediate candidates for an ICD
typically prescribed for temporary use in patients who have recently experienced a MI, undergone CABG, or have newly diagnosed CM with severely reduced EF.
bridge to more permanent solutions until patient’s condition stabilizes
what is an ablation?
medical procedure used to treat certain arrhythmias by destroyed small areas of heart tissue that are responsible for the abnormal electrical signals. this intervention is typically performed when medications are ineffective or not well tolerated by the patient. ablation can be conducted using different energy sources, such as radiofrequency or cryotherapy, to achieve desired therapeutic effect
both aim to create scar tissue in the heart which disrupts the pathway of abnormal electrical signals, thus restoring normal rhythm
how does radiofrequency ablation work?
involves delivering high-frequency electrical energy through a catheter to heat and destroy the targeted tissue.
how does cryoablation work?
utilizes extreme cold to achieve tissue destruction.
describe an ablation procedure
there is insertion of catheters into blood vessels, usually through groin or neck, which are guided into heart under fluoro guidance. electrophysiological mapping is performed to pinpoint the exact location of the arrhythmogenic focus. once identified, the ablation catheter delivers energy to modify or eliminate the aberrant conduction pathway
what rhythms are typically treated with ablation?
AF, a flutter, SVT, some forms of VT
most successful with SVT and atrial flutter. AF may require repeat procedures
what is cardioversion?
medical procedure used to restore normal heart rhythm in patients experiencing certain types of abnormal heartbeats.
effective for treating afib, atrial flutter, and some VT
potential complications of an ablation
bleeding
infection at catheter site
cardiac perforation
damage to adjacent structures such as blood vessels or nerves
rarely, stroke or heart block
two main types of cardioversion
electrical and pharmacological
describe electrical cardioversion
involves delivering a controlled electrical shock to the heart through electrodes placed on chest or back. this shock momentarily stops all electrical activity in the heart, allowing the sinoatrial node to regain control and establish a regular rhythm. typically performed under sedation or anesthesia to minimze discomfort for the patient.
describe pharmacological cardioversion
uses antiarrhythmic medications to chemically restore normal heart rhythm
commonly used: amiodarone, flecainide, and propafenone
considerations prior to cardioversion
assess for presence of blood clots in the atria
-using TEE.
anticoagulation therapy may be intiated several weeks before and continued after procedure to reduce risk of stroke associated with clot dislodgement during rhythm restoration
success rate of cardioversion depends on several factors
-type and duration of arrhythmia
-underlying heart conditions
-patient-specific characteristics
complications from cardioversion
-skin burns from electrode pads
-arrhythmias induced by the shock itself
-thromboembolic events if AC is inadequate
what is defibrillation?
the delivery of a therapeutic dose of electrical energy to the heart using a defibrillator. primary goal is to depolarize a critical mass of heart muscle, terminating arrhythmia and allowing SA node to reestablish effective rhythm.
specifically used in VF and pulseless VT
rapid defib is crucual. significantly increases chances or ROSC
what are the two options for pad placement for defib?
typical range of joules for biphasic defibrillators?
anterior-lateral or anterior-posterior
120-200 joules
what can orthopnea or paroxysmal nocturnal dyspnea indicate?
pulmonary congestion/ increased pulmonary venous pressure due to left sided heart dysfunction (HF)
how does non-invasive ventilation work?
delivers positive pressure through a mask that fits over the nose, mouth, or both to provide ventilatory support (improve gas exchange/ decrease WOB) to patients without need for invasive artificial airways.
describe continuous positive airway pressure (CPAP)
provides a constant level of pressure throughout the respiratory cycle, which helps keep the airways open and prevents alveolar collapse
particularly useful with OSA and CHF where upper airways collapse or pulmonary edema may occur
describe bilevel positive airway pressure (BiPap)
offers two levels of pressure: a higher inspiratory positive airway pressure (IPAP) and a lower expiratory positive airway pressure (EPAP).
beneficial for patients who require assistance with both inhalation and exhalation (COPD exacerbations and certain neuromuscular conditions)
how is NIV useful in cardiac patients?
useful in managing acute heart failure by reducing preload and afterload, which decreased workload of heart and improves CO
hels alleviate symptoms of dyspnea, improve oxygenation, and reduce need for intubation
complications of NIV
skin breakdown
gastric distention from air swallowing
contraindications of NIV
severe hypoxemia requiring immediate intubation, facial trauma, deformities that prevent proper mask fitting, uncooperative behavior
primary goal of mechanical ventilation
ensure adequate oxygenation and carbon dioxide removal. achieved by delivering controlled breaths to the patient, either fully or partially supporting their respiratory efforts. can be delivered invasively (intubation) or noninvasively with mask.
describe assist control AC ventilation
ventilator provides a set tidal volume at a predetermined rate while allowing spontaneous breaths
describe synchronized intermittent mandatory ventilation (SIMV)
permits sponteneous breathing between mandatory breaths
desribe pressure support ventilation (PSV)
auguments spontaenous breaths with preset pressure
how does mechanical ventilation impact hemodynamics?
positive pressure ventilation can affect venous return and CO by increasing intrathoracic pressure
-reduces LV preload and afterload
-think about pHTN and intubation. increased risk to code
add more later
potential complications with mechanical ventilation
-barotrauma from excessive airway pressures
-volutrauma due to high tidal volumes
-VAP
functions of the renal system
regulates fluid and electrolyte balance
acid base balance
removes waste products
controls blood pressure
the functional unit responsible for filtering blood in the kidneys is called
nephron
the nephron consists of ________
a glomerulus and a tubular componenet
where does filtration occur in the nephron?
the glomerulus. blood enters through afferent arterioles. substances like glucose and electrolyes are reabsorbed. waste products like urea and creatine are excreted.
how does the RAAS system work? renin angiotensin aldosterone system
when blood pressure drops, juxtaglomerular cells in the kidneys release renin, which converts angiotensinogen to angiotensin I. further converts to angiotensin II, leading to vasoconstriction and increased BP. angiotensin II also stimulates aldosterone release from the adrenal glands, promoting sodium and water excretion
the kidneys regulate the levels of which electrolyes?
sodium, potassium, calcium, and phosphate by adjusting their reabsorption and excretion
kidneys also play a role in acid base balance by
excreting hydrogen ions and reabsorbing bicarbonate from urine
the kidneys produce erythropoietin,
a hormone that stimualates red blood cell production in response to hypoxia
kidneys convert vitamin D to its active form,
calcitriol, which is essential for calcium absorption from the GI tract
what is renal replacement therapy? name the modalities
procedure used to replace the normal blood-filtering function of the kidneys when they are no longer able to perform adequately. filter waste products, excess fluids, and toxins from the blood.
several modalities: HD, peritoneal dialysis, renal transplantation
what is peritoneal dialysis?
uses patient’s peritoneum in the abdomen as a natural filter. a catheter is surgically placed into the peritoneal cavity, allowing dialysis fluid to be infused. waste products and excess fluids pass from the blood vessels in the peritoneum into this fluid, which is then drained and replaced with fresh solution.
describe hemodialysis
blood is diverted from the patient’s body through a machine known as a dialyzer or artificial kidney. the dialyzer contains a semi-permeable membrance that facilitates the exchanges of solutes between the blood and a specially formulated dialysis solution called dialysate. as flood blows from the dialyzer, waste products such as urea and creatinine, along with excess electrolytes like potassium and phosphate, diffuse across the membrance into the dialysate. simultaneously, certain essential electrolyes may be returned to the blood to maintain physiological balance
patients undergoing HD often experience rapid fluid removal and electrolyte shifts, which can lead to
hypotension, arrhythmias, or cardiac arrest
what is disquilibrium syndrome?
characterized by neurological symptoms caused by rapid removal of urea during hemodialysis.
This can lead to an imbalance in the level of fluid inside the cells of the brain, causing swelling and symptoms such as headache, nausea, restlessness, confusion, or in severe cases, seizures, coma, and death.
why must nurses collaborate with pharmacists and nephrologists?
HD can influence pharmacokinetics of drugs by altering the drug clearance rates. will need medication dosage adjustments
what is continuous renal replacement therapy (CRRT)?
a form of dialysis used to treat patients with AKI particularly in ICU to provide continuous, gentle removal of waste products and excess fluid from the blood, mimicking natural function of the kidneys.
operates over 24 hours, allowing for flow and steady solute clearance and fluid removal. reduces risk of hypotension and otehr complications associated with rapid fluid shifts
who is CRRT beneficial for?
hemodynamically unstable patients who cannot tolerate the rapid fluid shifts associated with traditional iHD
describe CVVH continuous venovenous hemofiltration
solutes are primarly removed by convection where a large fluid volume is filtered out and replaced with substitution fluid
describe CVVHD continueous venovenous hemodialysis
relies on diffusion across semipermeable membrane where dialysate flows countercurrently to blood flow, promoting solute clearance
describe CVVHDF continuous venovenous hemodiafiltration
combines both convection and diffusion, offering comprehensive solute removal
CRRT involves AC to prevent clotting within the circuit, these meds are often used
heparin or citrate
what is SCUF? slow continuous ultrafiltration
a RRT primarily used to manage fluid overload in patients with acute HF or CKD. a form of CRRT that focuses on the removal of excess fluid without significant solute clearance, making it distinct from other modalities like HD or hemofiltration
how does SCUF work?
using a semipermeable membrance to facilitate the movement of plasma water across the membrance due to a pressure gradient. allows for extraction of fluid at a controlled rate, typically from 100 to 500 mL per hour.
blood is pumped through extracorpeal circuit containing the ultrafiltration device where ultrafiltration occurs across the membrane. the filtered fluid, known as ultrafiltrate, is collected and discarded, while the remaining blood components are returned to the patient’s circulation
primary goal of SCUF
volume control rather than solute removal
who is SCUF beneficial for?
cardiac patients who present with fluid overload and are unresponsive to diuretics. offers gentle and continuous approach to fluid removal, reducing the risk of hemodynamic instability often associated with rapid fluid shifts in traditional dialysis methods.
nurses involved in SCUF most monitor several parameters
including blood flow rates, ultrafiltration rates, and patient hemodynamics
and assess electrolytes and hematocrit levels
What is targeted temperature management (TTM)?
intervention used in the management of patients who have experienced cardiac arrest. it involves deliberate reduction of a patient’s core body temperature to optimize neurological outcomes following rescuscitation. primary goal is to mitigate neurological damage by reducing metabolic demand and inhibiting determental biochemical processes that occur after ischemic injury.
beneficial to patients who remain comatose after ROSC following cardiac arrest
describe the process of TTM
cooling patient to targeted temp usually between 32 and 36 C (89.6-96.8 F) for a specific duration (often 24 hours) followed by a controlled rewarming phase.
physiological rationale behind TTM
based on its ability to reduce cerebral metabolic rate, thereby decreasing oxygen demand and limiting cascade of events leading to neuronal injury. cooling helps stabilize cell membrances, reduce excitotoxicity, and limit inflammatory responses. can also prevent or minimize reperfusion injury, which can exacerbate brain damage after blood flow is restored.
methods for inducing hypothermia
surface cooling with ice packs or cooling blankets
endovascular cooling devices
cold IV fluids
during TTM be sure to monitor
shivering
electrolyte imbalances
coagulopathy
infections
shivering must be managed as it can increase metabolic rate and counteract benefits of cooling
why must rewarming by gradual after TTM?
to prevent rapid shifts in electrolytes and hemodynamics that could lead to complications such as rebound hyperthermia or hypotension.
should proceed at a rate of approx 0.25 C to 0.5 C per hour until normothermia achieved
palliative care involves managing symptoms such as
pain, dyspnea, fatigue, and anxiety
