chapter 12 pt1 Flashcards
which electrolyte imbalance is associated with life threatening arrhythmia?
potassium disorders - particularly hyperkalemia (acute hyperkalemia reponsible for life threatening cardiac arrhythmia )
less commonly disorders in serum calcium and magnesium
role of potassium in cell electrolyte homeostasis ?
extracellular potassium grad tightly controlled between 3.5-5
large conc gradient exists between extra cell and intracell fluid compartments
when serum ph decreases - academia , serum potassium increases - potassium shifts in this instance from intra to extra , vice versa
what patients do you see electrolyte imbalance ?
hyperkalemia :
chronic kidney disease or AKI
combination of drugs - ACE-I, ARB, potassium sparing diuretics ,NSAIDS, beta blockers , trimethoprim)
tissue breakdown - rhabdomyolysis, hemolysisi , tumor lysis
DKA
addison disease
diet
spurious - - pseudohyperkalemia - from clotted blood
clinical manifestation of hyperkalemia ?
weakness > flaccid paralysis >parathesia >depressed deep tendon reflexes
ECG abnormalities - if 6.7 and above
what re the ECG abnormalities in hyperkalemia ?
first degree heart block - PR interval more than 0.2
flat or absent P waves
tall peaked tented T waves (T wave larger than r wave)
ST depression
S and T wave merge
wide QRS >0.12s
VTACH
bradycardia
what is the treatment of hyperkalemia ?
IF ECG CHANGES SEEN - WITHOUT LAB - START LIFE SAVING TREATMENT
K >6.5
=EXPERT HELP
=10ml of IV 10 percent calcium chloride over 2-5 mins
or
= 30ml of IV 10% calcium gluconate over 15 mins
TIS PROTECTS THE HEART BY ANTAGONISING THE EFFECT OF POTASSIUM BUT DOES NOT REDUCE THE POTASSIUM LEVELS
Use shifting agents for this
or remove potassium from the body
e) CONTINIOUS CARDIAC MONITORING
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2)
=>6.5 but no ECG changes
a) SEEK EXPERT HELP
b) SHIFTING POTASSIUM :
10 units of short acting insulin
and 25g glucose IV over 15-30 mins
IF PRE TREATMENT BLOOD GLUCOSE IS <7MMOL L
then 10 units of short acting insulin with 25g of glucose IV over 15-30 mins
THEN FOLLOWED BY 10 percent glucose infusion at 50ml/hr for 5 hours
c) WITH glucose/ insulin also give NEBULISED SALBUTAMOL
10-20mg nebuliser over 4-6 hours
d) removing potassium from body:
dialysis
sodium zirconium - 5-10g TDS for 3 days
e) CONTINIOUS CARDIAC MONITORING
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Moderate elevation 6-6.4
shift potassium intracellularly with insulin glucose
(no need for salbutamol)
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mild elevation 5.5 -5.9
adress cause and further rise of K( such as drugs , and diet)
use calcium resonium -15 g 3–4 times a day.
or 30g by retention enema
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4)
monitoring serum potassium and glucose conc
5)
prevention of reoccurrence
risk associated with treating hyperkalemia ?
hypoglycaemia - if giving insulin / glucose
usually occur within 3 hours of initiating treatment
may occur after 6 hours after infusion end
tissue necrosis - secondary to extravasation of calcium sats
rebound hyperkalemia - monitor serum potassium for min 24 hour after treatment
how to modify ALS according to hyperkalemia ?
DURING CPR
blood gas analysis confirmation
protect the heart
shift potassium into cells
if severe acidosis - sodium bicarbonate - 50mmol (50ml of 8.4 percent solution) IV STAT (avoid missing with calcium chloride)
remove potassium from body - dialysis for hyperkalemic cardiac arrest resistant to medicaltreatmnet
when is hypokalaemia in patient a risk for sudden cardiac arrest ? - most common
pre-existing heart disease
treated with digoxin
definition of hypokalemia
<3.5
severe <2.5
causes of hypokalaemia?
gastrointestinal - diarrhea and vomiting
drug - diuretics , laxative steroids
renal tubular disorder , Diabetes insipiduus , dialysis
endocrine - cushing and hyperaldostronisism
metabolic alkalosis
magnesium depletion
poor dietary intake
symptoms of hypokalaemia ?
fatigue
weakness
leg crams
constipation
<2.5
rhabdomyolysis
ascending paralysis
resp difficulty
ecg features of hypokalaemia ?
u waves
t wave flattening
ST segment changes
arrhythmia esy taking digoxin
hypokalaemia treatment ?
if unstable arrythmia - AND ONLY IN UNSTABLE ARRYTHMIA AND CARDIAC ARREST IS IMMINENT iv potassium
2MMOL per min for ten min , followed by 10 MMOL over 5-10 min
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OTHERWISE ALWAYS maximum is 20mmol/h
gradual potassium relacement preferred
max recommended dose through IV is 20mmol per hour
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CONTINUOUS ECG MONITORING when IV infused , dose titrated after repeated potassium sampling
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many patient deficient in magnesium also
ECG changes of hypercalcemia ?
short QT interval
prolong QRS interval
flat T waves
AV block
cardiac arrest
