Lateral traction during shoulder arthroscopy: its effect on tissue perfusion measured by pulse oximetry.

We studied the effect of three methods of shoulder traction during arthroscopy on arterial oxygen saturation measured by a pulse oximeter applied to the fingertip of the arm in traction. Simple longitudinal traction ablated the oxygen saturation in only 1 of 30 patients. Adding vertical traction perpendicular to the arm ablated the oxygen saturation in 25 of 30 patients when a 2-inch wide sling was used and in 7 of 30 patients when a 4-inch sling was used. In this series, the pulse oximeter did not demonstrate gradual gradations in arterial oxygen saturation loss. Rather, the pulse oximeter provided an all-or-none warning signal for tissue hypoxia.