Infusion Misdirection in Microincisional Vitrectomy Surgery

Purpose To review the incidence and possible mechanisms of 2 problems caused by infusion misdirection during microincisional vitrectomy in 1 physician’s practice and to find an estimate of the broader occurrence among other physicians. Design Observational series of 1 surgeon’s cases over 2 periods. A survey also was sent to other retinal specialists. Participants Patients undergoing microincisional vitrectomy. Methods The physician tracked the occurrence of intraoperative hypotony and unintentional anterior chamber air infusion in his practice. A survey was sent to 2000 members of the American Society of Retina Specialists and the Retina Society. Main Outcome Measures Primary outcome measure was the incidence of hypotony during microincisional vitrectomy, defined as softening of the globe to the point of corneal or scleral infolding, or both, that resolved with repositioning of the infusion cannula. The secondary outcome measure was incidence of unplanned air flow into the anterior chamber. Survey questions included frequency of observed infusion interruption and incidence of inadvertent anterior chamber air infusion. Results In the earlier series, of 232 vitrectomies, 37 (16%) showed signs of episodic hypotony after infusion blockage. Seven cases (3%) showed inadvertent air flow into the anterior chamber. One hundred fifty-two physicians responded to the survey. Fifty-seven percent reported infusion blockage and hypotony in 1% to 5% of cases. Fifty-nine percent reported air flow into the anterior chamber in some cases. In the later series, 12 instances of infusion blockage were noted in 118 cases. Awareness of the issue and additional attention to the infusion line taping did not prevent the problem from occurring. In the survey, most respondents reported observing both infusion interruption and inadvertent anterior chamber air infusion on occasion. Conclusions Infusion misdirection resulting in hypotony or air flow into the anterior chamber seems to be infrequent, but it remains a risk. Awareness of the problem reduces the incidence, but does not eliminate it. The potential inadvertently to touch the retina, choroid, or lens increases when these events occur. Infusion misdirection can be avoided by maintaining the correct position of the cannula, which may be facilitated by an external support to the tubing.