Pulse oximeter-induced digital injury: frequency rate and possible causative factors.

OBJECTIVE: To study the frequency rate of and factors associated with pulse oximeter-induced digital injury (PIDI).
DESIGN: Prospective descriptive study.
SETTING: Surgical intensive care unit of a university hospital. PATIENTS: All patients with a length of stay of >2 days. INTERVENTIONS AND MAIN
RESULTS: We monitored 125 patients by using a pulse oximeter with a nondisposable clip-on probe changed every 3-4 hrs from one finger to another. Daily inspection was performed with special attention to digital injury. Factors implicated in the pathogenesis of PIDI, such as vasopressor therapy, hypotension, hypoxia, hypothermia, and arterial cannulation of the radial or ulnar artery were recorded daily. A total of 22 patients received norepinephrine and dopamine, 34 patients were given dopamine, and 69 patients did not receive vasoactive drugs. PIDI developed in 6 of 125 patients, five in the norepinephrine/dopamine group, one in the dopamine group, and none in the patients not receiving vasopressors. When comparing the frequency rate of PIDI in patients receiving norepinephrine (5 of 22) with patients not receiving norepinephrine (1 of 103) the relationship between the use of norepinephrine and PIDI is significant (p < .001). However, this relationship may also be explained by the fact that patients in the norepinephrine group were more severely ill than patients not requiring norepinephrine were. This is reflected by a higher median severity of illness score (Simplified Acute Physiology Score II) (p = .001), median duration of hypotension (p < .001), median number of saturation drops (p < .001), and higher mortality rate (p < .001). Hypothermia did not occur in any of the patients. There was no significant difference between the median right-left difference in duration of arterial cannulation between the two subgroups (p = .8). In all surviving patients, PIDI healed without permanent damage.
CONCLUSIONS: In the studied population of critically ill patients in a surgical intensive care unit, the frequency rate of PIDI was 5% (6 of 125). Although an association with the use of norepinephrine was found, this small number of cases does not allow definite statistical conclusions concerning a relationship between the possible causative factors and PIDI. However, severely ill patients, as indicated by their need for more aggressive vasopressors, are more likely to develop PIDI. In survivors, PIDI healed without sequelae.