Depends on what the processing office decides. Most likely, if you've not received a passport request yet, you're going to end up having to redo the medical because they don't normally submit a request for passports when there's only a month left on your medicals. It would not allow you enough time to get your passport there and back, and to enter Canada to land, because (without an extension on the medical) your Confirmation of Permanent Residence would not be valid for long enough. It expires the same date as the one year anniversary of your medical exam, or the expiration date of your passport - whichever comes first.