Pupillary dilation reflex and pupillary pain index evaluation during general anaesthesia: a pilot study

Background

Pupillary response by pupillary dilatation reflex (PDR) is a robust reflex, even measurable during general anaesthesia. However, the ability of infrared pupillometry to detect PDR differences obtained by intraoperative opioid administration in anaesthesized patients remains largely unknown. We analyzed the performance of automated infrared pupillometry in detecting differences in pupillary dilatation reflex response by a inbuilt standardized nociceptive stimulation program in patients under general anesthesia with a standardized propofol/fentanyl scheme.

Methods

In this single center, interventional cohort study 38 patients (24-74 years) were enrolled. Patients were anesthetized with propofol until loss of consciousness. Two dynamic pupil measurements were performed in each patient (before opioid administration and after opioid steady state). Automated infrared pupillometry was used to determine PDR during nociceptive stimulations (10-60 mA) applied by a inbuilt pupillary pain index protocol (PPI) to the skin area innervated by the median nerve. Increasing stimulations by protocol are device specific and automatically performed until pupil dilation of > 13%. Pupil characteristics, blood pressure, heart rate values were collected.

Results

After opioid administration, patients needed a higher stimulation intensity (45.26 mA vs 30.79 mA, p = 0.00001). PPI score showed a reduction after analgesic treatment (5.21 vs 7.68, p = 0.000001), resulting in a 32.16% score reduction.

Conclusions

PDR via automated increased tetanic stimulation may reflect opioid effect under general anaesthesia. Further research is required to detect possible confounding factors such as medication interaction and optimization of individualized opioid dosage.

Endarterectomy combined with retrograde stenting for tandem lesions of the carotid artery

OBJECTIVES

Due to its location in the chest wall, surgical treatment of lesions at the origin of the brachiocephalic trunk or common carotid artery (CCA) is unattractive. Complete endovascular treatment of lesions at the origin of the common carotid artery or brachiochephalic trunk combined with high-grade lesions at the carotid bifurcation carries a high risk for distal emboli before cerebral protection is installed. Therefore, the combination of open carotid endarterectomy with retrograde stenting of the proximal lesion through one stage is most attractive.

METHODS

Eleven patients were treated with a combined procedure for tandem lesions at the origin of the brachiocephalic trunk or common carotid artery (CCA) and the carotid bifurcation. Endpoint of this evaluation was the 30-day MACE (Major Adverse Cardiovascular Events).

RESULTS

All procedures were finished as planned and no conversion was necessary. Thirty-day mortality was 0%. One patient developed a restenosis after only 4 days for which he underwent a re-PTA procedure. The 30-day MACE was 0%. None of the patients needed additional treatment during follow-up (mean follow-up 33 months; range: 11 to 60) although one patient developed a non-significant stenosis during follow-up.

CONCLUSIONS

Combined treatment of tandem lesions of the carotid artery is safe and effective in the long-term.

A multicenter evaluation of the routine use of a new white cell-reduction apheresis system for collection of platelets

BACKGROUND

Residual white cells (WBCs) cause serious side effects in platelet transfusion. An in-line WBC-reduction system based on fluidized particle bed technology was recently developed as a modification of an existing plateletpheresis system.

STUDY DESIGN AND METHODS

In an investigational phase, three flow profiles were evaluated using prototype software in five centers, each using their standard conditions. In the confirmatory phase, the released software was tested in three centers. WBCs were counted in two full Nageotte grids (dilution 1-in-5).

RESULTS

With the prototype software, WBC levels were always below 1 x 10(6) per procedure (median, 25,000/procedure; n = 314). One profile proved to be superior to the other two with respect to platelet yield and residual WBCs, and it was incorporated in the released WBC-reduction system, together with a built-in process control. Median residual WBCs in these WBC-reduction system components not rejected by the process control were 19,000 per procedure (n = 211/225 total), with 99.5 percent of the platelet components having less than 1 x 10(6) WBCs.

CONCLUSION

The protocol selected in the initial phase, now available as a WBC-reduction system, results in platelet concentrates with very low residual WBC levels. This satisfies even the most stringent criteria for WBC reduction in platelets, without the platelet loss typically seen with conventional fiber filtration.