Capture stored procedure output

I've been tasked with executing a stored procedure and capturing the output.   Sounds, simple enough, sure, I can do that…

Naturally, I've lost my way and now can't seem to find the magic incantation to accomplish my task.   Here's what I've got.

I'm operating against a SQL Server 2008 R2 instance.  

I have the SQLPS module installed.

I have attempted multiple methods of executing a .sql file to execute the stored procedure.  The contents of the .sql file are

"Exec ds_utilities.dbo.ds_test @db = 'whatever'"

The ds_test stored procedure is as follows:

USE [ds_utilities]

GO

/****** Object:  StoredProcedure [dbo].[ds_test]    Script Date: 8/24/2015 1:22:05 PM ******/

SET ANSI_NULLS ON

GO

SET QUOTED_IDENTIFIER ON

GO

/******* This proc checks for objects with uneeded .dbo. in definition, runs ds_check_id/ds_create_metadata,

 runs smart_indexer,checks for any PK/FK renames needed and populates the rad_sys_db_verification_history table*********/

-- exec [ds_PQM5_check_mbw] [empty_Retail2013_1__preview_04]

ALTER   procedure [dbo].[ds_test] @db sysname

AS

set nocount on

declare @cnt int

declare @sql nvarchar (max)

select @db as parameter

print 'developers'

Select @sql = 'select top 2 * from [ds_utilities].[dbo].[Developer] '

execute(@sql)

print 'greate developers'

select top 2 * from [ds_utilities].[dbo].[Developer] where name like '%spoo%'

#############################################

The output is as follows.

Results:

Parameter

1 Whatever

  developer_id  name                data_architect_flag   email_address

developer_id  name                data_architect_flag   email_address

Messages

Developers

Greate developers

#####################################################

I'm past the point of receiving errors, I just can't seem to extract the above output from my results.

My question is, what object/property/methods can I use to capture all of the above output?   I've tried Invoke-SQLCmd but only seem to be able to retrieve the "Parameter" value of "Whatever".   I've also tried a System.Data.SqlClient.SqlCommand object with ExecuteReader() but couldn't figure out how to access the additional output in that either.  Same with System.data.sqlclient.sqldataadapter.  If figure what I'm looking for has gotta be in one of these somewhere unless I'm totally off base.   Since I don't have an unlimited amount of time I'm coming here to see if someone can point me to a path home.

TIA