ECG: Hypokalemia

1. PROF.DR. G.SUNDARAMURTHY’S UNIT – M5

2. ECG OF THE WEEK
Prof. G Sundaramurthy’s Unit
P.Vanjinathan

3. 52 yrs old male,
C/o Loose stools X 4 days
8-10 episodes/day, watery
assc. vomiting +
No blood/mucus/tenesmus
H/o Vomiting +
4 – 5 episodes/day
Colourless, watery, non-bilious, no blood
H/o Fatiguability +
H/o Cramps +

4. •ON EXAMINATION:
Pulse– 76 per min
BP---100/70mmHg
RR---16per min

5. ECG

7. •HR - 70/min
•Rhythm - Normal sinus rhythm
•PR interval - 0.12 sec
•P wave - Normal morphology
•QRS interval - 0.08 sec
•QT interval - Prolonged
•QRS Voltage - Normal
•QRS axis - Normal axis
•R wave progression - Normal

8. •Abnormal Q wave - No abnormal Q wave
•ST segment - Depression in V
3
-V
6

•T wave - Amplitude decreased
•U wave - Seen in L
ӀI
, L
ӀII
,aVF,V
2
-V
6

9. INVESTIGATIONS
•CBC--- NORMAL
•URINE ROUTINE---NORMAL
•RFT---UREA- 30mgs/dl
CREAT-0.9mgs/dl
ELECTROLYTES---Na---128meq
K----2.7meq

10. ECG Changes in Hypokalemia
Early changes:
•Flattening or inversion of T waves
•Prominent U waves
•ST segment depression
•Prolonged QT interval
Severe Potassium depletion:
•Prolonged PR interval
•Decreased voltage of QRS
•Widening of QRS complex
•Ventricular arrhythmia

11. Causes of Hypokalemia
•Decreased intake
2.Redistribution into cells
–Acid base - Metabolic acidosis
–Hormonal – Insulin, β2 agonist, α-Antagonist.
–Anabolic state – B
12
/ Folic acid supplements
–Others – Pseudohypokalemia, Hypothermia, Hypokalemic
periodic paralysis

12. 1.Increased Loss
A.Non renal - GI loss, Integumentary loss (sweat)
B.Renal -
•Increased distal flow: diuretics, osmotic diuresis, salt-
wasting nephropathies
•Increased secretion of potassium:
–Mineralocorticoid excess: Primary hyperaldosteronism,
Secondary hyperaldosteronism (malignant hypertension, Renin-
secreting tumors, Renal artery stenosis, Hypovolemia),
Congenital adrenal hyperplasia, Cushing's syndrome, Bartter's
syndrome
–Distal delivery of non-reabsorbed anions: vomiting, NG suction,
proximal (type 2) RTA, DKA, penicillin derivatives
–Others: Amphotericin B, Liddle's syndrome, Hypomagnesemia

13. CLINICAL FEATURES
•Neuromuscular: Fatigue, myalgia, and muscular weakness of the lower
extremities.
–Smooth muscle involvement – Constipation, ileus, urinary retention
–progressive weakness, hypoventilation (due to respiratory muscle
involvement), and eventually complete paralysis
•Impaired ability of kidneys to concentrate urine – Polyuria, urine with low
osmolality, polydipsia
•GI manifestations:
–Anorexia, nausea, vomiting
–Constipation, Abdominal distension, paralytic ileus
•CVS – Arrhythmias
•Metabolic alkalosis

14. Treatment
•Correct volume depletion & Rx of underlying etiology
•Estimate the K
+
deficit
–1 mEq/L = Total body K
+
deficit of 200 to 400 mEq
•If no ECG changes - start oral K
+
supplementation
•If ECG changes present – Start I.V K
+
repletion
–Rate of < 20 mEq/hr
–In peripheral vein < 40 mEq/L
–In central vein < 60 mEq/L
•Monitor K
+
during therapy
•Search for & Rx hypomagnesemia

15. Treatment Contd...
•Preparations Available
–Various salts of K
+
: Cl
-
, HCO
3
-
, Phosphate & Gluconate salts
–KCl : More effective in hypokalemia with metabolic alkalosis
. (e.g. Diuretic usage, Diarrhea)
–KHCO
3
/ K Citrate : Hypokalemia & metabolic acidosis (e.g. RTA)

16. THANK YOU