When using sans-serif math, I have found that upright-shape subscripts can clash with the slanted-shape variables they are attached to, as shown in particular with `p_{in}`, `p_t` and `Q_{in}`:

[![enter image description here](https://i.stack.imgur.com/M7EJe.png)](https://i.stack.imgur.com/M7EJe.png)
[![enter image description here](https://i.stack.imgur.com/QbGlS.png)](https://i.stack.imgur.com/QbGlS.png)

It is important that the `p` remains in slanted shape and the subscript is in upright shape due to a typographic convention I must adhere to. I would also like the equations to match the helvetica style font in the body of the document, however I am willing to change this if there is no way to fix this problem.

The lines I use to change the document font are:

```
\usepackage[scaled=1.0]{helvet}
\renewcommand\familydefault{\sfdefault}

\linespread{1.6}  

```

I also use `amsmath`.

I have tried various different ways to style the equation font, such as: 

```
\usepackage{sansmathfonts}  
%\usepackage[italic]{mathastext}

```

I used both `\text` and `\mathrm` on the subscript in each case and got the same problems of clashing text. I am using pdfLatex to prduce the pdf file with texmaker.

Any help to fix this or letting me know there is no way around this would be really appreciated. 
thanks

Oh, and here is the equation I am using: 

```
\begin{equation}  
\alpha_t V_{t} \frac{\partial p_t}{\partial t} = \frac{2 \uppi K R L}{h} \bigg( \frac{1}{2} ( p_{in} + p_{out}) - p_{t} \bigg) - M V_{t}   
\label{eq:metabolism balance}   
\end{equation} 

```