Measurement of bronchodilatation using a superfine fibreoptic bronchoscope

Abstract

In this study, we report the development and accuracy of a direct technique to measure airway calibre using a superfine fibreoptic bronchoscope. Ten mongrel dogs were anaesthetized with pentobarbitone and the trachea intubated with a tracheal tube; the small lumen of the tube allowed passage of a superfine fibreoptic bronchoscope (od 2.2 mm). Bronchial cross-sectional area and airway pressure were recorded continuously and dynamic pulmonary compliance and airway resistance calculated. The dogs were allocated to one of two groups. In the first group (six dogs), bronchoconstriction was induced with histamine 10 micrograms kg-1 i.v. and 500 micrograms kg-1 h-1 c.i.v. Thirty minutes later, adrenaline 0-0.4 mg kg-1 was given i.v. Bronchial cross-sectional area, dynamic pulmonary compliance and airway resistance were assessed simultaneously. In the second group, 0.9% saline was given 30 min after placement of the superfine fibreoptic bronchoscope and 10 min later atropine 0.1 microgram kg-1 was administered. In the first group, histamine decreased mean percentage bronchial cross-sectional area by 49.2 (SD 11.5) %, reduced dynamic pulmonary compliance from 32.1 (12.6) to 22.3 (5.2) ml cm H2O-1 and increased airway resistance from 39.1 (11.6) to 57.2 (10.2) cm H2O litre-1 s-1. Adrenaline produced a dose-dependent increase in percentage bronchial cross-sectional area and dynamic pulmonary compliance to 119.4 (31.3)% and 27.4 (5.5) ml cm H2O-1, respectively, and a decrease in airway resistance to 43.9 (7.2) cm H2O litre-1 s-1. There were significant correlations between percentage bronchial cross-sectional area and dynamic pulmonary compliance (r = 0.720, P < 0.0001) and airway resistance (r = 0.727, P < 0.0001). Atropine 0.1 mg kg-1 increased basal bronchial cross-sectional area to 137.5 (16.9) %. These data indicate that adrenaline reversed histamine- and pentobarbitone-induced bronchoconstriction.

In vivo spasmolytic effect of ketamine and adrenaline on histamine‐induced airway constriction

“…Systolic blood pressure was kept above 80 mmHg with fluid loading (lactate Ringer's solution: 50 ml . kg-l) and with continuous phenylephrine infusion at 0.5-2.0 pg * kg-l-min-' whose rate was dependent on systolic blood pressure and could not significantly affect histamine-induced bronchoconstriction (15).…”

“…Therefore, we have developed a portable direct method using a superfine fibreoptic bronchoscope to assess changes in bronchial calibre (13)(14)(15). We have found that the bronchoscopic method is more specific to assess airway calibre than indirect methods as, when assessing Yobronchial cross-sectional area (BCA) completely returned to prehistamine value by adrenaline administration, yet %dynamic pulmonary compliance (C+) and %airway resistance (Raw) did not (15). In addition, there was a significant correlation between %BCA and %Cdyn (r=0.720, P<O.OOOl) and %BCA and %Raw (r= 0.727, P<O.OOOl) (15).…”

“…However, recent studies indicated that the indirect measurements are not quite reliable (11,12). Thus, we developed a new direct method to assess airway calibre, which is based on the use of a superfine fibreoptic bronchoscope (13)(14)(15). We employed this method to evaluate the effect of ketamine on bronchoconstriction induced by histamine in dogs.…”

Study on airway smooth muscle tone using fiberoptic bronchoscopy: basic research and clinical application

“…To validate a direct visualization method using a superfine fiberoptic bronchoscope, we compared the percent (%) bronchial cross-sectional area with percent (%) airway resistance and percent (%) dynamic compliance in a histamine-bronchoconstriction model [11]. Epinephrine dosedependently decreased and increased airway resistance and dynamic compliance, respectively.…”

“…b Significant correlations between % bronchial cross-sectional area and % dynamic pulmonary compliance (r = 0.720, P \ 0.0001) and % airway resistance (r = 0.727, P \ 0.0001). (Figure modified from Otomo et al[11] with the publisher'…”