Nd:YAG laser and photodynamic therapy for esophageal and endobronchial tumors under general and local anesthesia. Effects on arterial blood gas levels.

STUDY OBJECTIVE

Our objective was to determine the respiratory and acid-base metabolism response to endoscopic laser surgery for obstructive tumors, as related to the duration and different types of endoscopy, anesthesia, and laser treatment.

DESIGN

The design was a case-control, cohort analytic, nonrandomized controlled survey of case series before and after endoscopic procedures.

SETTING

A referral-based surgery and oncology practice at one hospital's laser center.

PATIENTS

We studied a sequential sample of 82 patients in the age range from 35 to 92 years, with malignant and benign, primary and metastatic, partially and completely obstructing esophageal (15 patients) and endobronchial (67 patients) tumors.

INTERVENTIONS

A total of 229 diagnostic, laser treatment, and follow-up endoscopic procedures was performed under general or local anesthesia (46 esophagoscopies and 183 bronchoscopies). The latter group consisted of 29 cases of general and 154 cases of local topical anesthesia. The last group involved 37 diagnostic and toilet bronchoscopies, 86 cases of YAG-laser tumor ablation, and 31 cases of PDT.

MEASUREMENTS AND MAIN RESULTS

Direct-reading electrode measurements of arterial blood, sampled before and immediately after the endoscopic procedure, revealed statistically significant (p less than 0.001) increases in PaCO2 (200 of 229 cases) and decreases in pH (195 of 229 cases) and PaO2 (215 of 229 cases). These findings were similar after bronchoscopy and esophagoscopy, general and local anesthesia (only the decrease in pH was less pronounced in the latter case), and explorative endoscopies and different laser treatments and did not correlate with the total duration of the procedure within the wide time range of 7 to 210 minutes. The initial preoperative level of PaCO2 was considerably higher and the level of PaO2 was significantly lower in patients with endobronchial tumors, as compared to patients with esophageal cancer. A strong, inverse linear relationship was found between the perioperative changes in PaO2 and its initial level and between PaCO2 and pH changes.

CONCLUSIONS

The PDT for esophageal and endobronchial malignancies is no more harmful for acid-base metabolism and respiratory functions than YAG-laser tumor ablation or any other common, nonlaser endoscopic procedure.