Prevention of ventilatory disturbance while in the face‐down position after macular hole surgery

Abstract

The aim of the present study was to assess the effects of the face-down position on ventilatory function after macular hole surgery. The transcutaneous carbon dioxide tensions (tcPCO2) were measured in five patients who had undergone intraocular tamponade and in 17 normal subjects. The tcPCO2 measurements were done in patients following vitrectomy in the sitting position and in the prone position with their faces down over the semi-closed spaces of the conventional mats. In normal subjects, minute ventilatory volumes (V.E) were measured simultaneously with tcPCO2 in the sitting position and prone position. The newly introduced face-down mats (new mats) for the prone position were also tested in the normal subjects. In normal subjects, VE in the prone position with the conventional mats was significantly lower than that found in the sitting position (5.06 +/- 1.55 vs 6.06 +/- 1.64 L/min; P < 0.002). The tcPCO2 in the prone position was significantly higher than that in the sitting position (41.7 +/- 2.1 vs 38.0 +/- 1.9 mmHg; P < 0.0001). In post-vitrectomy patients, tcPCO2 in the prone position with the conventional mats was significantly higher than that in the sitting position (41.4 +/- 1.7 vs 38.6 +/- 2.2 mmHg; P < 0.02). The tcPCO2 in the prone position in normal subjects was significantly lower using new mats than that when using conventional mats. The use of conventional mats during a prone position, increased the tcPCO2 values when compared to the tcPCO2 values obtained during the sitting position in patients following vitrectomy. This could be due to either a decrease of the VE caused by limited thoracic movement or rebreathing of the exhaled gas over the semi-closed space, or both. The new mats might be useful in alleviating the increase of tcPCO2 by eliminating the rebreathing of the exhaled gas.

Vision Impairment by Choice: Why Do Patients Decline Macular Hole Surgery?

“…The issue of post-surgical positioning has received due attention. Studies have investigated the effect of positioning time, 10,18−20 compliance to positioning, 21 as well as issues relating to breathing difficulties 22 and the utility of massage. 23 In addition, Cullen 14 published an extremely useful list of guidelines for patients on how to properly prepare for the experience of remaining face-down for an extended period of time.…”

Combined pars plana lensectomy/vitrectomy for idiopathic macular hole repair without postoperative prone positioning

“…16 Furthermore, PPP may be associated with ventilatory disturbances in some patients by decreasing the minute ventilatory volumes and increasing transcutaneous carbon dioxide tensions. 57 More importantly, Foster and Chou reported that the tolerance angle, defined as the cone angle away from the position in which a hole is situated at the apex of a gas bubble, within which a patient can maneuver and still allow for complete hole tamponade, increases with increasing intraocular fill, thus making postoperative positioning less critical. 58 They calculated that for a 60 to 90 percent gas fill, the tolerance angle is about 90 to 120 degrees respectively for holes in the size range of a MH.…”