Although not a medical negligence claim, Crown Resorts Limited v Zantran Pty Limited  FCAFC 1 (available on JADE) is a useful appellate consideration of the issue of express obligations of confidence allegedly preventing voluntary communications with the solicitors for opposing party in litigation.
The discussion included an analysis of Richards v Kadian 64 NSWLR 204,
A useful passage appears at  per Allsop CJ:
…there can be no doubt as to the importance of the over-arching purpose and case management considerations to be found in Pt VB, and like provisions. They do not, however, form an adequate foundation for a conclusion that it is against public policy for a party in litigation to seek to enforce a valid contractual confidentiality clause when to do so would or might impede the conduct of private civil litigation. This is especially so when there are pre-trial interlocutory procedures that may be availed of to extract the information from prospective witnesses prior to, or at an early and separate stage of, the trial.