Although in 15% of patients indirect laryngoscopy could not be performed because of excessive gag reflex, indirect laryngoscopy can serve as an effective method to predict difficult intubation.

To investigate the effects of surfactant proteins B (SP-B) and C (SP-C) on lung mechanics, we compared tidal and static lung volumes of immature rabbits anesthetized with pentobarbital sodium and given reconstituted test surfactants (RTS). With a series of RTS having various SP-B concentrations (0-0.7%) but a fixed SP-C concentration (1.4%), both the tidal volume with 25-cmH2O insufflation pressure and the static volume deflated to 5-cmH2O airway pressure increased, significantly correlating with the SP-B concentration: the former increased from 6.5 to 26.0 ml/kg (mean), and the latter increased from 6.4 to 31.8 ml/kg. With another series of RTS having a fixed SP-B concentration (0.7%) but various SP-C concentrations (0-1.4%), the tidal volume increased from 5.1 to 24.8 ml/kg, significantly correlating with the SP-C concentration, whereas the static volume increased from 3.4 to 32.0 ml/kg, the ceiling value, in the presence of a minimal concentration of SP-C (0. 18%). In conclusion, certain doses of SP-B and SP-C were indispensable for optimizing dynamic lung mechanics; the static mechanics, however, required significantly less SP-C.

Neuromuscular-blocking effects on the diaphragm can be recorded in vivo. According to direct contractile force measurement, the diaphragm is more resistant to non-depolarizing neuromuscular-blocking drugs than the tibialis anterior muscle.

Hypothesizing that seronegative patients are as sensitive to vecuronium as seropositive patients, we assessed sensitivity in seropositive and seronegative myasthenia gravis (MG) patients and in non-MG patients. They were, indeed, both equally sensitive to vecuronium.

Purpose: To clarify the relationship between neuromuscular block and train-of-four fade and to investigate the causes of these drug-dependent differences, we compared the neuromuscular block and TOF fade after pancuronium, vecuronium and rocuronium.Methods: In 24 anesthetized rats, the sciatic nerve was stimulated, and the twitch of left tibialis anterior muscle was recorded. After T 1 (first twitch response) was kept constant at 95% block by administration of pancuronium, vecuronium, or rocuronium (n=8, in each), the TOF fade was measured when T 1 block was decreased to 40% and 20%. In addition, using 24 phrenic nerve-diaphragm preparations, the fade was measured when the T 1 block increased to 20% and 40% by titrating of either one of the three drugs (n=8, in each). Results: In in vivo experiments, the fade produced by pancuronium was greater than that by vecuronium or rocuronium when T 1 block was at 40% (81 ± 9 vs 63 ± 15 and 63 ± 6%, respectively) and at 20% (66 ± 13 vs 34 ± 17 and 40 ± 6%, respectively). In contrast, in in vitro experiments, the differences did not reach significant levels among the three drugs either at 20% (32 ± 19 vs 33 ± 10 and 32 ± 17%) or 40% of block (62 ± 29 vs 65 ± 14 and 55 ± 14%). Conclusions: For vecuronium and rocuronium, the results were similar in vivo and in vitro. For pancuronium, fade was greater in vivo. These results suggest that different neuromuscular blocking agent have different relationships between the fade and the block. In vitro results might not be the same as in vivo, possibly due to pharmacokinetic differences.