Blood Flow in the Rabbit Tracheal Mucosa under Normal Conditions and under the Influence of Tracheal Intubation

Abstract

Isotope labelled microspheres were used to study the capillary blood perfusion of the rabbit tracheal mucosa. Under resting conditions the perfusion was about 0.3 ml/min - g (i.e. about 60% of the relative cerebral blood flow). Irritation of the tracheal mucosa by an endotracheal tube caused a steep rise in blood flow, tenfold or more. This was probably due to relaxation of the arterioles caused by a release of histamine-like substances. When an endotracheal tube is equipped with a small cuff (small resting diameter, low residual volume), the part of the mucosa in contact with the cuff, i.e. the mucosa covering the surface and edges of the cartilages, will be ischaemic at a cuff to tracheal wall pressure (C-T pressure) of greater than 30 millimeters of mercury. This abrupt ischaemia threshold contributes to the risk of deep mucosal damage with subsequent tracheal scarring, possibly proceeding to stenosis. Our present studies indicate that the ideal large cuff, with properties resembling those of an air cushion, will allow the major part of the arterial pressure to be propagated as far down as the capillaries. Under these conditions the cuff would permit some of the capillary blood perfusion of the tracheal mucosa covering the cartilages also at C-T pressures exceeding 30 mmHg. Although this investigation supports the concept that the ideal thin-walled large cuff interferes much less with the mucosal blood perfusion than the small cuff, we recommend that the cuff pressure be monitored and kept below 20 mmHg.

The tracheobronchial epithelium of the bonnet monkey (Macaca radiata): A quantitative ultrastructural study

“…Airway epithelium is now used as a well-established model of chemical carcinogenesis (Becci et al, 1978a, Nettesheim et al, 1981. Airway epithelium is also used in studies of the biology of wound repair (Gordon and Lane, 1980;Nordin et al, 1977;Schmidt et al, 1979) and the response to inhaled irritants such as sulfur dioxide (Lamb and Reid, 1968;Asmundson et al, 1973;Clark et al, 19801, ozone (Penha and Werthamer, 1974;Boatman et al, 1974;Schwartz et al, 1976;Mellick et al, 1977;Castleman et al, 1977), tobacco smoke (Frasca et al, 1968b;Hayashi et al, 19781, and marijuana smoke (Hayashi et al, 1979). Most of these experiments use laboratory rodents.…”

Cochlear Blood Circulation Studied with Microspheres

“…Earlier studies o f the blood flow in other organs have shown that even slight injuries to the organ may give a considerable rise o f the blood flow (Nordin et al, 1977;Lindblom et al, 1978). In the present investigation we were unable to demonstrate that infectious diseases o f the middle ear or surgery o f the middle or inner ear caused any changes o f the blood flow within the cochlea.…”

Effects of intravenous diclofenac on postoperative sore throat in patients undergoing laparoscopic surgery at Aga Khan University Hospital, Nairobi: A prospective, randomized, double blind controlled trial

“…The pathogenesis of POST is attributed to trauma, local irritation and inflammation of the airway mucosa during tracheal intubation [13][14][15] . This tissue damage results in the release of prostaglandins which cause inflammation and pain 20,40,41 .…”

“…The incidence of postoperative sore throat (POST) after tracheal intubation varies from 6.6 to 90% [7][8][9][10][11][12] . The pathogenesis of POST is attributed to traumatisation, local irritation and inflammation of the airway mucosa during tracheal intubation [13][14][15] . Numerous non-pharmacological and pharmacological measures aimed at attenuating POST have been investigated with varying success.…”