Pentax Airway Scope® vs Macintosh laryngoscope for tracheal intubation in adult patients: a systematic review and meta-analysis.

The Pentax Airway Scope(®) is a single-use optical videolaryngoscope designed to assist with difficult tracheal intubation. We systematically reviewed the efficacy of the Pentax Airway Scope with that of a conventional laryngoscope for tracheal intubation in adults with 'normal' and 'difficult' airways. We included 17 randomised controlled trials with a total of 1801 participants. We used the DerSimonian and Laird random-effects model to calculate pooled relative risk or weighted mean differences. The relative risk (95% CI) of a Cormack-Lehane grade-1 laryngeal view was 2.40 (1.76-2.49) with the Pentax Airway Scope compared with the Macintosh laryngoscope, p < 0.00001. We found no other differences between the two laryngoscopes. Despite a superior laryngeal view, the Pentax Airway Scope provides little clinical benefit over the conventional laryngoscope.

Repetitive post-training exposure to enflurane modifies spatial memory in mice.

BACKGROUND: Previously the authors found that a single post-training exposure to enflurane or isoflurane, but not halothane, enhanced memory storage in an active avoidance task, which is a behavior with underlying mechanisms that are poorly understood and still debated. In contrast, spatial tasks are known to depend on hippocampal functions. This study investigated the effects of repetitive post-training exposure to enflurane on spatial memory in mice. METHODS: Using an eight-arm radial maze, 80 mice were trained to eat a pellet placed on the end of each of the eight arms. Training occurred on four consecutive days with one trial per day. The number of errors in the first eight choices was recorded to determine performances for each day of training. Immediately after each training session, mice in the enflurane group received 1 h exposure to 0.5%, 1%, or 2% enflurane in air through a calibrated vaporizer. The performance ratios (the ratio of errors on each day compared with the first day of the 4 days) in the control and the enflurane groups were compared. RESULTS: The performance ratios (which equals the mean of the error in the fourth day/the error in the first day) in the control, and 0.5%, 1%, and 2% enflurane groups were 0.66, 0.65, and 0.32 (P < 0.01, vs. control), and 0.46 (P < 0.05, vs. control), respectively. CONCLUSIONS: Repetitive post-training exposure to 1% and 2% enflurane significantly enhanced spatial memory in the eight-arm radial maze task. Enflurane enhances consolidation of spatial memory, possibly by affecting hippocampal activity.

Multiple but different genetic factors underlie enflurane and isoflurane requirements studied through backcross analysis in C57BL and ddN mice.

We performed a classic backcross analysis to examine the basic genetic nature of enflurane (ENF) and isoflurane (ISO) anesthetic requirement in two inbred mice strains, C57BL (BL) and ddN. We have previously reported different ENF and ISO anesthetic requirements in these two strains. BL (n = 22) and ddN (n = 26) mice were used as parents and were reciprocally crossed to produce F1 hybrid mice. Each F1 offspring was crossed to its parent to produce backcross siblings (BF1). Anesthetic end point was determined as the loss of righting reflex. Measurement of anesthetic requirement was performed during 8-12 wk after birth. Although ddN mice showed slightly less resistance to ENF and ISO compared with our previous report, they were more resistant than BL mice. Multivariate regression analysis of parents' and F1 hybrids' data revealed that, while maternal factors and factors on autosomes were related to both anesthetics, the factors on the X chromosome were ENF specific. A wide variation in anesthetic requirements among BF1 progeny suggested multifactorial inheritance. The regression equations obtained did not always predict anesthetic requirement in BF1 progeny. These discrepancies may be due to the epistatic interaction of related genes. We conclude that multiple but different genetic factors are involved in determining ENF and ISO anesthetic requirements in BL and ddN mice.

Psychomotor performance during initial stage of exposure to halothane, enflurane, isoflurane and sevoflurane in mice.

1. The dose-response relationship during the pre-anaesthetic and pre-equilibrium state of four inhalation anaesthetics (halothane, enflurane, isoflurane and sevoflurane) on fixed-ratio schedule-controlled behaviour was studied in mice. 2. Animals exposed to halothane, enflurane and isoflurane showed a biphasic pattern (i.e. a significant incremental increase in psychomotor responses at low inspired concentrations (0.1-0.4%) and decrements at greater concentrations) in a dose-dependent manner. Mean peak responses (per cent of control) were 132.3 (P < 0.01 vs control), 124.0 (P < 0.05) and 116.7% (P < 0.05) at 0.1% halothane, 0.3% enflurane and 0.2% isoflurane, respectively. 3. Sevoflurane did not increase schedule-controlled behavioural responses at any concentration. 4. The effect of subanaesthetic concentrations of inhalation anaesthetics on psychomotor performance can be evaluated as changes in the response rate in schedule-controlled behaviour.