Automated infusion control software adds risk of acute intraoperative hypotony
When automated infusion control systems are used, IOP is not measured directly but rather based on measurement of infusion line flow, which if slowed can cause the software to shut the pump off, potentially leaving the eye hypotonous.
In a review of 2 cases, Raymond Iezzi, MD, MS discussed the management of acute intraoperative hypotony associated with pump shutdown by the infusion control software, during a presentation as the 2020 ASRS Virtual Meeting.
Iezzi and colleagues used a silicone model eye and designed a 2-channel pressure measurement system to continuously measure the IOP and infusion line pressure.
In the first case, the infusion line flow was partially restricted during the separation of the posterior vitreous, resulting in the infusion pump shutting off and leading to hypotony. The infusion control system was shut off, the line was repositioned, and the footswitch was used to elevate IOP.
In the second case during pars plana vitrectomy, the infusion line was flattened as a result of softening of the eye, resulting in the automatic pump shutting down. IOP was normalized using the same method as in the first case. Researchers noted that when infusion flow into the model eye was lowered via a stopcock valve, infusion line pressure greatly exceeded intraocular pressure and inaccurate IOP calculations by the control software resulted in the pump shutting off. Raising the pressure to 60 mmHg did not change the IOP but hypotony was corrected by shutting off infusion control at the vitrectomy screen, correcting the position of the infusion cannula, and raising IOP via the footswitch.
“Automated infusion control software introduces added risk of acute intraoperative hypotony,” Dr Iezzi concluded. “Restriction of infusion flow may result in infusion pump shutdown and hypotony when automated infusion control software is active. Management of acute hypotony in such cases requires that the surgeon immediately bypass the infusion control software, correct the infusion line position, and elevate the IOP.”
Iezzi R, et al. Acute Intraoperative Hypotony During Automated Infusion Control. Presented at: 2020 ASRS Virtual Meeting.