Effect of Bronchoconstriction-induced Ventilation–Perfusion Mismatch on Uptake and Elimination of Isoflurane and Desflurane

Kretzschmar, Moritz; Kozian, Alf; Baumgardner, James E.; Borges, João Batista; Hedenstierna, Göran; Larsson, Anders; Hachenberg, Thomas; Schilling, Thomas

doi:10.1097/aln.0000000000001847

Cited by 5 publications

(18 citation statements)

References 28 publications

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“…This finding is remarkable, as lung modeling in the absence of nitrous oxide predicts that increasing V̇/Q̇ scatter, with a reduction in effective alveolar ventilation, impairs alveolar-capillary gas exchange more severely for less soluble gases, 15 a prediction recently confirmed in an animal study of desflurane or isoflurane anesthesia using methacholine inhalation to induce increased V̇/Q̇ inhomogeneity. 25 This would suggest that inclusion of nitrous oxide might maintain the efficiency of the lung in exchanging less soluble modern volatile agents in the face of V̇/Q̇ scatter induced by anesthesia itself.…”

Section: Discussionmentioning

confidence: 99%

Can Mathematical Modeling Explain the Measured Magnitude of the Second Gas Effect?

2018

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Background Recent clinical studies suggest that the magnitude of the second gas effect is considerably greater on arterial blood partial pressures of volatile agents than on end-expired partial pressures, and a significant second gas effect on blood partial pressures of oxygen and volatile agents occurs even at relatively low rates of nitrous oxide uptake. We set out to further investigate the mechanism of this phenomenon with the help of mathematical modeling. Methods Log-normal distributions of ventilation and blood flow were generated representing the range of ventilation-perfusion scatter seen in patients during general anesthesia. Mixtures of nominal delivered concentrations of volatile agents (desflurane, isoflurane and diethyl ether) with and without 70% nitrous oxide were mathematically modeled using steady state mass-balance principles, and the magnitude of the second gas effect calculated as an augmentation ratio for the volatile agent, defined as the partial pressure in the presence to that in the absence of nitrous oxide. Results Increasing the degree of mismatch increased the second gas effect in blood. Simultaneously, the second gas effect decreased in the gas phase. The increase in blood was greatest for the least soluble gas, desflurane, and least for the most soluble gas, diethyl ether, while opposite results applied in the gas phase. Conclusions Modeling of ventilation-perfusion inhomogeneity confirms that the second gas effect is greater in blood than in expired gas. Gas-based minimum alveolar concentration readings may therefore underestimate the depth of anesthesia during nitrous oxide anesthesia with volatile agents. The effect on minimum alveolar concentration is likely to be most pronounced for the less soluble volatile agents in current use.

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Section: Discussionmentioning

confidence: 99%

Can Mathematical Modeling Explain the Measured Magnitude of the Second Gas Effect?

2018

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“…Conversely, a previous study in a porcine obstructive lung model demonstrated that both uptake and elimination of desflurane were delayed by bronchoconstriction [5]. Moreover, the uptake and elimination of isoflurane, which has a higher blood solubility than desflurane, were less affected by bronchoconstriction, suggesting that the pharmacokinetics of desflurane were likely to be affected by bronchoconstriction due to its low solubility.…”

Section: Introductionmentioning

confidence: 77%

“…Flow diagram detailing the selection of patients included in the retrospective analysis. Ninety-one patients were excluded due to non-curative surgery, multiple procedures for the cancer during the study period, incomplete records, and receiving both forms of anesthesia during surgery delayed desflurane elimination [5]. In this animal model, the investigators elucidated that the elimination of desflurane was affected by ventilation-perfusion (V/Q) scatter caused by the shift of ventilation distribution and perfusion dispersion.…”

Section: Discussionmentioning

confidence: 99%

Longer time to extubation after general anesthesia with desflurane in patients with obstructive respiratory dysfunction: a retrospective study

et al. 2021

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Background The prospect of patients with obstructive respiratory dysfunction undergoing surgery has increased with the growth in the elderly population; however, there have been few investigations about the recovery profile from volatile anesthesia. This study aimed to investigate the impact of obstructive respiratory dysfunction on recovery from desflurane anesthesia. Methods A retrospective cohort study included patients who underwent orthopedic lower limb surgery between September 2018 and March 2020. Patients were divided into two groups: those whose preoperative forced expiratory volume in 1 s/forced vital capacity ratio was <70% (obstructive respiratory dysfunction group, n = 180) or ≥70% (control group, n = 45). Time from discontinuation of desflurane to extubation (extubation time) was compared between the two groups. Univariate and multivariable Cox regression models were used to compare odds ratios for prolonged extubation (≥10 min). Results A total of 45 patients with obstructive respiratory dysfunction and 180 control patients were eligible for analysis. Extubation time was significantly longer in patients in the obstructive respiratory dysfunction group than those in the control group. In the multivariable Cox model, male sex (HR = 2.00, 95% CI 1.12–3.57; P = 0.020) and obstructive respiratory dysfunction (HR = 2.07, 95% CI 1.05–4.08; P = 0.036) were associated with prolonged extubation. Conclusions This retrospective study indicated that extubation time was longer in patients with obstructive respiratory function than in patients without obstructive respiratory function. Male sex and obstructive respiratory function were factors that contributed to extubation time.

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“…Q distributions. 20,[24][25][26] Also, some previous experimental and mathematical modeling studies have investigated the effects of individual changes in minute ventilation or cardiac output on anesthetic kinetics, 2,[6][7][8]14,15,30,41,42 or parallel changes in both cardiac output and minute ventilation. 5 The interventions that produced the three different .…”

Section: Perioperative Medicinementioning

confidence: 99%

“…Q mode with little shunt or alveolar dead space. 24,25 Our experiments were not blinded, and the order of . V A / .…”

Section: Perioperative Medicinementioning

confidence: 99%

Arterial and Mixed Venous Kinetics of Desflurane and Sevoflurane, Administered Simultaneously, at Three Different Global Ventilation to Perfusion Ratios in Piglets with Normal Lungs

et al. 2021

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Background Previous studies have established the role of various tissue compartments in the kinetics of inhaled anesthetic uptake and elimination. The role of normal lungs in inhaled anesthetic kinetics is less understood. In juvenile pigs with normal lungs, the authors measured desflurane and sevoflurane washin and washout kinetics at three different ratios of alveolar minute ventilation to cardiac output value. The main hypothesis was that the ventilation/perfusion ratio (VA/Q) of normal lungs influences the kinetics of inhaled anesthetics. Methods Seven healthy pigs were anesthetized with intravenous anesthetics and mechanically ventilated. Each animal was studied under three different VA/Q conditions: normal, low, and high. For each VA/Q condition, desflurane and sevoflurane were administered at a constant, subanesthetic inspired partial pressure (0.15 volume% for sevoflurane and 0.5 volume% for desflurane) for 45 min. Pulmonary arterial and systemic arterial blood samples were collected at eight time points during uptake, and then at these same times during elimination, for measurement of desflurane and sevoflurane partial pressures. The authors also assessed the effect of VA/Q on paired differences in arterial and mixed venous partial pressures. Results For desflurane washin, the scaled arterial partial pressure differences between 5 and 0 min were 0.70 ± 0.10, 0.93 ± 0.08, and 0.82 ± 0.07 for the low, normal, and high VA/Q conditions (means, 95% CI). Equivalent measurements for sevoflurane were 0.55 ± 0.06, 0.77 ± 0.04, and 0.75 ± 0.08. For desflurane washout, the scaled arterial partial pressure differences between 0 and 5 min were 0.76 ± 0.04, 0.88 ± 0.02, and 0.92 ± 0.01 for the low, normal, and high VA/Q conditions. Equivalent measurements for sevoflurane were 0.79 ± 0.05, 0.85 ± 0.03, and 0.90 ± 0.03. Conclusions Kinetics of inhaled anesthetic washin and washout are substantially altered by changes in the global VA/Q ratio for normal lungs. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New

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Effect of Bronchoconstriction-induced Ventilation–Perfusion Mismatch on Uptake and Elimination of Isoflurane and Desflurane

Cited by 5 publications

References 28 publications

Can Mathematical Modeling Explain the Measured Magnitude of the Second Gas Effect?

Can Mathematical Modeling Explain the Measured Magnitude of the Second Gas Effect?

Longer time to extubation after general anesthesia with desflurane in patients with obstructive respiratory dysfunction: a retrospective study

Arterial and Mixed Venous Kinetics of Desflurane and Sevoflurane, Administered Simultaneously, at Three Different Global Ventilation to Perfusion Ratios in Piglets with Normal Lungs

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