cardiac rhythm disturbances + acid/base balance and buffers

patho/pharm exam 3

P wave

when the atria contract to fill the ventricles (atrial depolarization)

QRS complex

when ventricles contract (ventricle depolarization)

T wave

when ventricles are at rest (ventricular repolarization)

dysrhythmias

problem with impulse formation and impulse conduction causing abnormal heart rhythms. Affects cardiac output and perfusion.

sinus rhythm disorders

problems that start in the SA node. SA node happens at the P WAVE. (P wave issues)

sinus bradycardia 

SA node fires too slowly (< 60 bpm), decreases O2 demand, normal in athletes

vagal stimulation (causes SNS to decrease)

what can cause a sinus bradycardia reaction?

sinus tachycardia

SA node fires too fast (>100 bpm), increase in O2 depmand, the faster the heart is beating, the harder it is to fill chambers.

beta blockers (atenolol), DILTIAZAM (calicum channel blocker)

what drugs are used to treat sinus tachycardia?

caffeine, nicotine, alcohol, cocaine

what can cause HR to increase?

heart block

a delay or interruption in the electrical signal. Pathway is partially or completely blocked, slowing, or stopping heart beat.

sinus arrest/pause 

SA node fails to fire temporarely causing disruption in P wave.

Missing P wave and QRS for a period of time.

CPR, amiodarone, epinephrine

how do you treat sinus arrest/pause?

atrial fibrilation

an irregular, rapid heart rhythm where the atria quiver instead of contracting effectively and cause decrease in filling time. No P WAVE.

Radial pulse may be slower than apical pulse!

clots in the atria → stroke risk

what is the biggest risk for atrial fibrillation?

control rate with diltiazam + control rhythm with cardioversion

treatment for atrial fibrillation?

cardioversion

to correct abnormal rhythm, used when pt is STILL ALIVE (HAS A PULSE) and needs to have rhythm interrupted or reset

MUST PRE-MEDICATE + set monitor to SYNCHRONIZE (will send electricity with QRS complex)

defibrillation

to restart the heart in cardiac arrest, used when pt is DEAD (NO PULSE)

unsynchronized shock given at any time (MUST TURN OFF SYNCHRONIZE)

premature ventricular contraction (PVC)

an extra early heartbeat that starts in the ventricle instead of the SA node, decrease CO. Ventricles will contract before they have time to fill.

unifocal PVC

all PVCs look the same shape and come from one spot in the ventricle. Less serious.

multifocal PVC

electricity shooting off from multiple places in the ventricle, PVCs look all different shapes and sizes 

R-on-T phenomenon

a PVC lands right on the T-wave of the previous beat, so PVC hits while heart is recharging. Comes very quickly after QRS complex.

VERY DANGEROUS can cause ventricular fibrillation!

treatment of PVCs?

O2 + correct electrolytes, drugs (lidocane, amidodarone)

ventricular tachycardia

a fast, unstable rhythm that starts in the ventricles instead of the SA node, ventricles fire rapidly + independently. Reduces ventricular filling time and decreases CO.

how to treat ventricular tachycardia with stable pulse?

amiodarone, liodcane, cardiovert (if unstable)

toursades de pointes

polymorphic ventricular tachycardia where QRS rotates around baseline, deflecting downward and upward several beats

Usually caused my Mg deficiency or antibiotics (macrolides)

Mg sulfate or cardioversion

how to treat toursades de pointes?

ventricular fibrillation

life threatening cardiac arrest rhythm where the ventricles quiver chaotically instead of contracting. Chaotic pattern of electrical activity in the ventricles.

quivering ventricles → no CO → no pulse → dead

no P waves, QRS, or T-wave. Looks like a bag of worms

metabolic acidosis, MI, electrocution

what causes ventricular fibrillation?

treatment for ventricular fibrilation?

start CPR immediately, defibrillate, epinephrine or vasopressin, AMIODARONE

what does it mean is defibrillator reads “no shock advised”

means there is no electricity in pts body so electricity wont help

electrolytes important for heart?

K+, Mg, Ca+

amiodarone

most common antiarrhythmics for ventricular issues?

dysrhythmia symptoms

SOB, diaphoresis, chest pain, hypotension, heart failure, palpations

bicarbonate (HCO3-)

a base (alkaline substance) that helps the body neutralize acid and maintain normal pH balance. Major Buffer System!

regulated by the KIDNEYS

long process where kidneys do bulk of work and takes about 1.5 days to fix metabolic issues

how long does bicarbonate take to fix issues?

PaCO2

an acidic gas measures how well the lungs are ventilating. Measure CO2 level which reflects respiratory function. 

sleepy, hypoventilation, shallow slow breathing

signs of being acidotic

normal pH value

7.35-7.45

low (< 7.35) → acidic

high (> 7.45) → alkaline 

normal PaCO2 value (LUNGS + RESPIRATORY)

35-45 mmHg

low (< 35) → alkaline

high (> 45) → acidic

normal HCO3- value (KIDNEYS + METABOLIC)

22-26 mEq/L

low (< 22) → acidic

high (> 26) → alkaline

primary event

what started the issue, either respiratory or metabolic

compensation

body’s effort to adapt to primary event with either lungs or kidneys helping the issue

partial compensation

pH level of opposite organ than one with issue are moving in nopposite direction to help the problem

(ex. during metabolic acidosis the lungs will hyperventilate to help so pH levels begin increasing)

respiratory acidosis

decrease in pH + increase in PaCO2

barely breathing, HYPOVENTILATION (not enough O2)

NO HCO3- TO TREAT

narcotics, sleep apnea, neuro injury, pain when breathing

what causes respiratory acidosis?

sleep apnea

upper airway obstruction, waking up many times during the night bc cannot breath

S+S → snoring, being exhaused, secretions

CPAP (continuous posive airway pressure)

one continues steady pressure of O2. Keeps airways open.

Used for sleep apnea

BiPAP (bilevel positive airway pressure)

two pressure levels higher O2 upon inhalation and low CO2 when exhaling. Aids in ventilation/breathes for pt.

Used for COPD or respiratory failure

Respiratory alkalosis

decrease in pH + decrease PCO2

body trying to cool down, HYPERVENTILATION

sepsis, fever, pain, anxiety

what is respiratoy alkalosis caused by?

metabolic acidosis

decrease in pH + decrease in HCO3-

excessive loss of bicarbonate, causes DIARRHEA

shock, kidney disease (pts norm will be more acidic), hypoxemia

what causes metabolic acidosis?

chronic lung or kidney disease

when is the only time bicarbonate (HCO3-) is used to treat?

metabolic alkalosis

increase in pH + increase in HCO3-

excessive increase of bicarbonate, causes VOMITING

hydrate (hypotonic fluids)

how to treat metabolic alkalosis?

normal PaO2 value

80-100 mmHg