Stored Procedures and knowing when they complete.

I have been tring to figure out how to know when a stored procedure (such as .ExecuteNonQuery()) has completed.

I have a loop that is for a text reader that is looking up ID's of records in the SqlServer table that need to be updated. However the loop is faster than the server and I am trying to figure out how to make the loop wait

Example:
using (tr = File.OpenText(myFilePath)
{

SqlCommand UpdateCmd = new SqlCommand("MyStoredProcedure", conn);

UpdateCmd.CommandType = CommandType.StoredProcedure;

while((templine = tr.ReadLine()) != null)

{

conn.Open();

UpdateCmd.Parameters.AddWithValue("@IDNumber", templine);

UpdateCmd.ExecuteNonQuery();

//this is the point at which I need to Wait for the Nonquery to finish.. How?

conn.Close();

}

}

I can get errors on similar issues like connection still open or you already have an open reader. etc.
Is there a quick and dirty way to make it wait for procedure to wait?

Any help will be appreciated.
Thanks
Frank