Powershell to monitor IIS AppPool & formatting the results

Hi all,
I am attempting to create a PowerShell script that I will ultimately plug into our application monitoring system;
Specifically, I am looking to create a script that will identify a specific IIS application pool, and then return the amount of memory used by that pool's worker process. I pretty much have it getting what I need, but in order to integrate this with our monitoring solution I need to format the output of the script a bit...
Here is what I have:

$serverName=$args[0]
$applicationPoolName=$args[1]
$memUsed = Get-WmiObject Win32_process -ComputerName $serverName | where CommandLine -Match $applicationPoolName | fl VM

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So, I call this script from a PowerShell prompt:
CheckAppPool.ps1 servername appPoolName

The results are returned as:
VM  :  123456789

I need to figure out a way to have the results returned to me so they look like this:
memUsed 123456789

Any assistance is greatly appreciated!!

Thanks,

David