Finding Total Lung Capacity

[1stYearGunner]

A patient breathes 12 times per minute. Vital capacity : 5 L. Functional residual capacity: 1.4L. Inspiratory reserve volume : 1.2L. What is the total lung capacity of the patient?

Weird question.
It seems like I have to guess what the tidal volume is. How do you people solve this problem?

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[EmetyreUSMLEStep1Tutor1]

12 RR is calm breathing in which tidal volume is 0,5 you dont need to guess

 

[Silverish]

12 RR is calm breathing in which tidal volume is 0,5 you dont need to guess

But by that logic you could just add FRC + IRV + 0.5 and get the answer
1.4 + 1.2 + 0.5 = 3.1, which is less than vital capacity (5L) alone, which means 0.5L cannot be the tidal volume.

Not enough information is given by OP.
I'm trying to work this one out, and it seems you're definitely going to have to assume either the TV or the residual volume.
In this case, I would just look at best answer between 5 and 6
Does patient have a restrictive or obstructive lung disease? Anything besides just these numbers?

 

[EmetyreUSMLEStep1Tutor1]

Vital capacity of 5 L - IRV of 1.2 = 3.8(ERV+ TV)
We know FRC(RV + ERV) is 1.4
then we assume that tidal volume is 0,5(12 RR normal breathing) and we still cannot figure out TLC
I agree that information is insufficient, or OP just confused volumes and capacities.

 

[1stYearGunner]

Ok perfect. I knew there was a mistake. I triple checked all values and terms used in the question. No other info was given. Thanks!