Effective today, the anaesthetic technicians will also be taking the collective action of working to rule to ensure their health and safety.
This includes finishing their shifts on time, working no overtime, and taking their scheduled lunch breaks without interruption.
Lakes District Health Board employs 11 anaesthetic technicians.
Lakes District Health Board acting chief executive Nick Saville-Wood said the DHB had always bargained in good faith and would continue to do so with APEX and its members.
He said while the strike action was regrettable for all concerned, Lakes DHB respected APEX members' right to strike.
Saville-Wood said Lakes DHB reiterated its desire to continue utilising mediation in an effort to resolve the parties' differences, and further mediation was being scheduled.
Lakes District Health Board acting chief operating officer Greg Vandergoot said anaesthetic technicians were an integral part of operating theatre teams and any operation requiring a general anaesthetic, had to have a technician present.
He said any changes to hospital operations were made to ensure the safety of patients was not compromised.
Lakes DHB apologises to those patients whose operations need to be rescheduled and whose healthcare plans will be affected.
Lakes DHB is working to contact all affected patients and rebook them as soon as possible.