Anesthesiology最新文献

The practice of anesthesiology is both an art and a science. Despite the increasing emphasis on using scientific evidence to inform clinical decisions, the "art" of considering the contextual intricacies surrounding those decisions is equally important. This article borrows concepts from quantum mechanics and discuss how anesthesiology, too, is practiced and researched in complex systems with intrinsic uncertainty and unpredictability. The authors encourage the reader to reflect on the influence of contextual factors when appraising and applying scientific evidence to their own practice.

Background: General anesthesia induces both unconsciousness and respiratory depression, but whether these effects share a common neural substrate remains unclear. The parafacial zone, a γ-aminobutyric acid-mediated (GABAergic) sleep-promoting region, has been proposed to modulate respiration. This study investigates whether parafacial zone GABAergic neurons function as a common neural node coordinating anesthetic-induced unconsciousness and respiratory suppression.

Methods: A total of 95 male mice (10 to 12 weeks old) were used. Chemogenetic and optogenetic methods targeted parafacial zone GABAergic neurons to assess anesthetic efficacy and respiratory changes. Immunostaining evaluated neuronal activation, and awake-state stimulation tested for anesthesia-like effects.

Results: Chemogenetic activation of parafacial zone GABAergic neurons enhanced anesthetic sensitivity, shifting the sevoflurane dose-response curve leftward (50% effective dose, 0.662%; 95% confidence interval, 0.624 to 0.699% vs . 1.569%; 95% confidence interval, 1.502 to 1.637%) and lowering the concentration required for loss of righting reflex (0.735 ± 0.027% vs . 1.601 ± 0.048%; P < 0.0001; n = 10). Induction was faster (48 ± 4 s vs . 112 ± 3 s; P < 0.0001; n = 8), and emergence was delayed (435 ± 12 s vs . 89 ± 12 s; P < 0.0001; n = 8). Electroencephalogram showed increased delta and decreased theta power. Respiratory rate declined significantly (183 ± 24 breaths/min vs . 471 ± 3 breaths/min; P < 0.0001; n = 8). During anesthesia, brief optogenetic activation of parafacial zone GABAergic neurons immediately elevated the burst suppression ratio (69.5 ± 5.1% vs . 32.5 ± 7.7%; P < 0.0001; n = 9) and reduced the respiratory rate (38 ± 13 breaths/min vs . 120 ± 21 breaths/min; P = 0.0016; n = 7), indicating concurrent modulation of cortical and respiratory function. Chemogenetic inhibition weakened anesthetic potency. Increased c-Fos expression in parafacial zone GABAergic neurons during sevoflurane anesthesia confirmed their recruitment. In awake mice, optogenetic activation alone induced a low-arousal state with several features of anesthesia, including hypoactivity, analgesia, respiratory depression, and cortical suppression without abolishing righting reflex.

Conclusions: The GABAergic parafacial zone is a shared critical node regulating both respiration and consciousness during sevoflurane anesthesia. Its activation suppresses both, helping explain anesthesia-related respiratory depression.

Background: Retrospective studies suggest that pulse oximetry overestimates saturation in children from races that may be associated with darker skin tone. Near-infrared spectroscopy (NIRS) relies on similar optical technology, but less is known about the effect of skin tone on NIRS. This study aimed to quantify the effect of skin tone on NIRS performance.

Methods: Consecutive patients under 21 yr old undergoing cardiac catheterization were enrolled (N = 110). Skin tone was measured using spectrophotometry. Regional oxygen saturation was recorded from a Medtronic (USA) INVOS 5100C NIRS device placed on the forehead and was compared to the mixed venous saturation. Multivariable linear regressions were used to determine the effect of skin tone measured by individual typology angle (ITA).

Results: Mean bias was larger for patients with darker skin in ITA categories 5 and 6 at -12.8% compared to ITA categories 3 and 4 at -2.5% with a difference of 10.3% (95% CI, 4.4 to 16.3; P < 0.001) and ITA categories 1 and 2 at 0.3% with a difference of 13.1% (95% CI, 7.5 to 18.7; P < 0.001). ITA was associated with NIRS bias in multivariable regression analysis (coefficient, 0.173; P < 0.001).

Conclusions: Darker skin tone is associated with worse NIRS performance and lower NIRS values compared to mixed venous saturation for the INVOS 5100C system. This may lead to differences in care and contribute to inequities in outcomes. Better validation guidelines are needed to ensure equity in performance across varying skin tones.

Mixtures of local anesthetics and adjuvants or mixtures of different local anesthetics are frequently used in regional anesthesia to accelerate the speed of onset and increase the effect and the length of action. Recent in vitro evidence revealed extensive crystallization in mixtures of local anesthetics or local anesthetic-adjuvant mixtures, including those previously deemed "safe"-like lidocaine plus sodium bicarbonate. Several guidelines recommend the use of local anesthetic-adjuvant or mixtures of local anesthetics. In this narrative review, the authors examine the chemical, pharmacologic, and clinical implications of local anesthetic mixture use, illustrate data on efficacy, and highlight critical limitations, including the risk of particle formation, lack of pharmacologic rationale, and unclear propensity for systemic toxicity. Moreover, the authors map out a practical risk versus benefit relationship with recommendations. In light of the unclear safety profile and equivocal clinical benefit of certain mixtures of local anesthetics and local anesthetic-adjuvant mixtures, the authors caution against the routine use of some mixtures at this point, especially for neuraxial techniques.