Since you have already gotten an item collection there's no need for any more API requests. When you call PodioItem::get_field_value() inside a loop like that it will be extremely slow because you are making a request to a remote server.
In this case it's unnecessary because you already have all the data. $item
contains all the field values:
foreach ($item_collection['items'] as $item_key => $item) {
$pname[] = $item->field(46702393);
$channel[] = $item->field(46702394);
$pname and $channel now contains an array of PodioItemField objects that you can work on.