A previously healthy 6-month-old boy is brought to the physician because of a 12-hour history of vomiting and diarrhea. He vomits after all feedings; the vomitus does not contain blood or bile. His mother says that he has had fewer wet diapers than usual during this period. He appears dehydrated and is crying without tears. He is at the 50th percentile for length and 30th percentile for weight. He appears lethargic. His temperature is 38°C (100.4°F), pulse is 180/min, and blood pressure is 60/40 mm Hg. Examination shows sunken eyes, dry mucous membranes, and a sunken anterior fontanel. Arterial blood gas analysis on room air shows:
pH 7.2
PCO2 38 mm Hg
PO2 90 mm Hg
Which of the following is the most likely explanation for this patient's arterial blood gas findings?
A ) Excessive metabolic acid formation
B ) Impaired ventilation
C ) Increased chloride loss
D ) Increased CO2 concentration in the extracellular fluid
E ) Increased metabolic acid produced by the gastrointestinal trac
prathapdoctor Forum Elite
Topics: 12 Posts: 406
01/14/07 - 11:27 PM
#2
D.increased CO 2 conc in the extracellular fluid.
prathapdoctor Forum Elite
Topics: 12 Posts: 406
01/15/07 - 08:19 AM
#3
but now i am thinking of A optioin,my explanation is
May be it is due to the loss of Chloride from diarrhea , as diarrhea give you metabolic acidosis .
I PICK C
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chemamr Moderator and PGY1
Topics: 703 Posts: 4,441
01/15/07 - 12:14 PM
#5
A? but not sure. ___________________ Any time something is written against me, I not only share the sentiment but feel I could do the job far better myself.
Guptashutosh Forum Elite
Topics: 35 Posts: 354
01/15/07 - 01:47 PM
#6
wel i have one explanation here, he has metabolic acidoses due to bicar loss in gi fluid in the form of vomiting and diarrhoea , which he shd have compensated with hyperventilation leadin to compensatory decreace in pCO2 but due to lack of ventilationg pCO2 remains 38 , so he has impaires or say failing respiration i guess ... option B
drashishmahajan Forum Senior
Topics: 6 Posts: 92
01/15/07 - 01:49 PM
#7
A---
impaired ventilation---pCO2 dec-- ruled out increase chloride loss--in vomiting theres exchange of bicarb wid chloride in the stomach which is thn lost in vomitus.this ll cause metabolic alkalosis-- ruled out inc co2 conc. --- nt possible since co2 being highly soluble in blood will raise the pco2 also---ruled out E option ca nt hold there
vanshita Forum Guru
Topics: 21 Posts: 812
01/16/07 - 08:58 AM
#8
C
fongch Forum Elite
Topics: 71 Posts: 316
05/10/07 - 11:18 AM
#9
I think your explanation makes sense.
prathapdoctor wrote: but now i am thinking of A optioin,my explanation is
