Relationship of muscle strength to potassium concentration in a hypokalaemic infant.
A nine-month infant, weighing 9.8 kg, presented with hypotonia secondary to acute hypokalaemia (1.0 mmol/l). Muscle strength improved as the serum potassium was increased. Muscle strength was assessed by the pressure generated inside a saline-filled endotracheal tube cuff during a grasp reflex. Potassium concentration and hand grip strength were related using a sigmoidal Emax model. Zero effect was assumed when the potassium concentration was zero. The Emax, EC50 and Hill coefficient values were determined by non-linear regression using the MKMODEL program. Parameter estimates (SE) were EC50 1.79 (0.15) mmol/l, Hill coefficient 3.79 (0.92), Emax 114.4 (8.9) mmHg.
Reid
A W
AW
Paediatric Intensive Care Unit, Starship Children's Hospital, Auckland, New Zealand.
Anderson
B J
BJ
Futter
M E
ME
Holford
N H
NH
D000208:Acute Disease; D000465:Algorithms; D018737:Hand Strength / Q000502:physiology; D006801:Humans; D007008:Hypokalemia / Q000097:blood* / Q000150:complications / Q000503:physiopathology; D007223:Infant; D008297:Male; D008954:Models, Biological; D009119:Muscle Contraction / Q000502:physiology; D009123:Muscle Hypotonia / Q000209:etiology; D018908:Muscle Weakness / Q000209:etiology; D017711:Nonlinear Dynamics; D011188:Potassium / Q000097:blood*; D012018:Reflex / Q000502:physiology; D012044:Regression Analysis
D011188:Potassium