Influence of the Concentration Effect on the Uptake of Anesthetic Mixtures

Epstein, Robert; Rackow, Herbert; Salanitre, Ernest; Wolf, Gerald

doi:10.1097/00000542-196405000-00015

Cited by 125 publications

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“…NUMBER of studies [1][2][3] have shown that the rapid uptake of high concentrations of nitrous oxide at induction of inhalational anesthesia produces an increase in alveolar concentrations of oxygen and the accompanying volatile anesthetic agent. This process is known as the second gas effect.…”

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confidence: 99%

Nitrous Oxide Diffusion and the Second Gas Effect on Emergence from Anesthesia

et al. 2011

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Background: Rapid elimination of nitrous oxide from the lungs at the end of inhalational anesthesia dilutes alveolar oxygen, producing "diffusion hypoxia." A similar dilutional effect on accompanying volatile anesthetic agent has not been evaluated and may impact the speed of emergence. Methods: Twenty patients undergoing surgery were randomly assigned to receive an anesthetic maintenance gas mixture of sevoflurane adjusted to bispectral index, in airoxygen (control group) versus a 2:1 mixture of nitrous oxideoxygen (nitrous oxide group). After surgery, baseline arterial and tidal gas samples were taken. Patients were ventilated with oxygen, and arterial and tidal gas sampling was repeated at 2 and 5 min. Arterial sampling was repeated 30 min after surgery. Sevoflurane partial pressure was measured in blood by the double headspace equilibration technique and in tidal gas using a calibrated infrared gas analyzer. Time to eye opening and time extubation were recorded. The primary endpoint was the reduction in sevoflurane partial pressures in blood at 2 and 5 min. Results: Relative to baseline, arterial sevoflurane partial pressure was 39% higher at 5 min in the control group (P Ͻ 0.04) versus the nitrous oxide group. At 30 min the difference was not statistically significant. Time to eye opening (8.7 vs. 10.1 min) and time to extubation (11.0 vs.13.2 min) were shorter in the nitrous oxide group versus the control group (P Ͻ 0.04). Conclusions: Elimination of nitrous oxide at the end of anesthesia produces a clinically significant acceleration in the

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Nitrous Oxide Diffusion and the Second Gas Effect on Emergence from Anesthesia

et al. 2011

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“…Also, the end-tidal alveolar concentration of the anesthetic is an indicator of the anesthetic concentration in the brain (12). The second gas effect was proposed by Epstein et al (1) and was proven in the consecutive study (13). However, in the study carried out by Sun et al (14), it was determined that the F A /F i ratio and arterial blood concentration did not show any difference with the addition of N 2 O to enflurane in the first five minutes; they claimed that the second gas effect is not a clinically valid concept.…”

Section: Discussionmentioning

confidence: 97%

“…It was reported that the addition of N 2 O during induction was beneficial due to the concentration and second gas effects (1)(2)(3). The second gas effect of N 2 O was identified for the first time in the study conducted by Epstein et al (1).…”

Section: Introductionmentioning

confidence: 94%

Nitrous Oxide Effects the Uptake of Sevoflurane to the Body During Induction

Erel¹,

Gürsoy²,

Kurt³

et al. 2018

meandros

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ÖzAmaç: İnhalasyon indüksiyonu sırasında azot protoksit gazının (N 2 O) sevofluranın vücuda alınması sürecinin hızı ve kalitesi üzerindeki etkilerini araştırmaktır. Gereç ve Yöntemler: Jinekolojik müdahale yapılması planlanan Amerikan Anestezistler Derneği kriterlerine göre I-II grubunda 84 kadın hasta randomize edilerek iki gruba ayrıldı. Tek soluk indüksiyonu yöntemi ile anestetize edilen hastalarda birinci gruba [Grup sevoflurane and azot protoksit (SA)] indüksiyonda %8 sevofluran, %67 azot protoksit ve %33 oksijen, ikinci gruba [Grup sevofluran (S) ve azot protoksit] %8 sevofluran ve %100 oksijen uygulandı. İndüksiyon sırasında oksijen, karbondioksit ve sevofluranın end-tidal ve inspiratuvar yoğunlukları, kirpik refleksinin kaybolmasına kadar geçen süre, gözlerin orta hatta gelmesi AbstractObjective: To determine the effects of nitrous oxide (N 2 O) on the speed and quality of the uptake process of sevoflurane during inhalation induction in adult patients. Materials and Methods: For randomized controlled study, eighty-four American Society of Anesthesiologists I-II patients undergoing gynecological interventions were randomly assigned to receive an 8% sevoflurane mixture with either 67% N 2 O plus 33% oxygen [Group sevoflurane and nitrous oxide (SA)] or 100% oxygen only [Group sevoflurane (S)]. Both groups were induced by a single-breath induction. End-tidal and inspiratory concentrations of respiratory and anesthetic gasses were continuously assessed during induction as well as time to loss of eyelash reflex, time to cessation of eye movements, and time to initiation of spontaneous breaths. Patients were intubated by the 5 th minute of induction and their vital signs, bispectral indexes, reflex responses to intubation and additional drug requirements for intubation were also recorded. Results: End-tidal sevoflurane concentrations and the ratio of alveolar to inspiratory sevoflurane concentrations (F A /F i ) of patients in group SA recorded at the 2 nd , the third and the 5 th minute of induction showed statistically significant increases when compared with patients in group S. Time to loss of eyelash reflex and time to cessation of eye movements were found to be decreased in group SA by 25 and 13%, respectively. Patients who presented with a reflex response to intubation in group S exceeded patients in group SA by 38.8% and patients who required additional medication for intubation in group S exceeded patients in group SA by 28.6%. Conclusion: The findings of this study support the view that administration of N 2 O improves the rate and quality of mask induction with sevoflurane. The benefits provided by N 2 O attributable to the concentrating and second gas effects appear during the first few minutes of induction (2 nd , 3 rd , and 4 th minutes) as well as during intubation when sevoflurane is used for mask induction.

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“…Objectif : Le concept de l'effet du deuxième gaz est bien connu, mais aucune étude n'a montré la relation qui existe entre la concentration alvéolaire d'oxygène et la pression Second gas effect of N 2 O on oxygen uptake HE concentration 1 and second gas effects 2 were first demonstrated in dogs. Increasing the inspired concentration of N 2 O concentrated both N 2 O and any gas delivered concurrently (the second gas) due to a difference of the blood/gas partition coefficient between N 2 and N 2 O.…”

Section: Discussionmentioning

confidence: 99%