Ion mobility spectrometry as a simple and rapid method to measure the plasma propofol concentrations for intravenous anaesthesia monitoring.

The plasma propofol concentration is important information for anaesthetists to monitor and adjust the anaesthesia depth for patients during a surgery operation. In this paper, a stand-alone ion mobility spectrometer (IMS) was constructed for the rapid measurement of the plasma propofol concentrations. Without any sample pre-treatment, the plasma samples were dropped on a piece of glass microfiber paper and then introduced into the IMS cell by the thermal desorption directly. Each individual measurement could be accomplished within 1 min. For the plasma propofol concentrations from 1 to 12 µg mL-1, the IMS response was linear with a correlation coefficient R2 of 0.998, while the limit of detection was evaluated to be 0.1 µg mL-1. These measurement results did meet the clinical application requirements. Furthermore, other clinically-often-used drugs, including remifentanil, flurbiprofen and atracurium, were found no significant interference with the qualitative and quantitative analysis of the plasma propofol. The plasma propofol concentrations measured by IMS were correlated well with those measured by the high performance liquid chromatography (HPLC). The results confirmed an excellent agreement between these two methods. Finally, this method was applied to monitor the plasma propofol concentrations for a patient undergoing surgery, demonstrating its capability of anaesthesia monitoring in real clinical environments.

Effects of different ventilation strategies on exhaled nitric oxide in geriatric abdominal surgery.

Exhaled nitric oxide (eNO) has been suggested to be a marker of small airway injury. We investigated the effects of different ventilation strategies on eNO. Sixty-nine patients who received elective open abdominal surgery under general anesthesia with more than 2 h of surgery duration were randomly divided into three groups: high tidal volume of 10-12 ml kg(-1) predicted body weight (PBW) with zero end-expiratory pressure (ZEEP) (high VT + ZEEP group); low tidal volume of 6-8 ml kg(-1) PBW with 8 cm H2O positive end-expiratory pressure (PEEP) (low VT + PEEP group); and low tidal volume of 6-8 ml kg(-1) PBW with 8 cm H2O PEEP and recruitment maneuvers (low VT + PEEP + RMs group). eNO, respiratory system compliance (Crs), oxygenation index, inflammatory mediators tumor necrosis factor-alpha (TNF-α), interleukin-1ß (IL-1ß), IL-8, prostaglandin E2 (PGE2) and PGF2a as well as pulmonary function were measured during the perioperative period. The postoperative eNO decreased in 78.3% of patients in the high VT + ZEEP group and low VT + PEEP group, and increased in 56.5% of patients in the low VT + PEEP + RMs group (P = 0.016). The Crs level in the high VT + ZEEP group significantly decreased with time but significantly increased in the low VT + PEEP + RMs group (P < 0.05). The oxygenation index, inflammatory mediators and pulmonary function did not statistically differ among the three groups. Compared with the low VT + PEEP + RMs group, the decreasing rate of postoperative eNO in the high VT + ZEEP and low VT + PEEP groups was higher, which may imply small airway injury during geriatric abdominal surgery.

Time-resolved dynamic dilution introduction for ion mobility spectrometry and its application in end-tidal propofol monitoring.

Based on the adsorption of analytes in the sampling loop, a time-resolved dynamic dilution introduction method was developed for negative ion mobility spectrometry to continuously monitor end-tidal propofol without other sample pre-separation. The dynamic dilution characteristics of propofol and moisture in the Teflon sample loop (4 mm o.d. and 2.4 mm i.d., 150 cm length) were both theoretically and experimentally investigated. The prominent absorption differences between propofol and moisture on the inwall of the sample loop allowed their concentrations to be time-resolved during the injection process, realizing sensitive measurement of end-tidal propofol with a response time of 2 s. At the optimized carrier gas flow rate of 700 mL min(-1), the linear response range for propofol was achieved to be 0.2 to 20 ppbv with a limit of detection (LOD) of 65 pptv. Finally, this method was performed on a patient undergoing mastectomy surgery to continuously monitor the end-tidal propofol with an interval of five respirations and the result nicely demonstrated its fast response to the propofol changes.

Blockade of PDE4B limits lung vascular permeability and lung inflammation in LPS-induced acute lung injury.

Acute lung injury (ALI), acute respiratory distress syndrome (ARDS), is actually involved in an ongoing and uncontrolled inflammatory response in lung tissues. Although extensive studies suggested that phospodiesterase type 4B (PDE4B) may be related to inflammation, the underlying cell biological mechanism of ALI remains unclear. To further investigate the mechanism how PDE4B take part in inflammatory response and the maintenance of vascular integrity, we established the experimental model of ALI in vitro and in vivo. In vitro, we found that Cilomilast, Diazepam and PDE4B knockout could potently inhibit the LPS-induced NF-κB activation and inflammatory response in multiple cell types, including lung epithelial cells (A549), pulmonary microvascular endothelial cells (PMVECs) and vascular smooth muscle cells (VSMCs). Besides, PDE4B deletion attenuated the LPS-induced ROS generation. In vivo, PDE4B deletion could attenuate the lung water content, histological signs of pulmonary injury and elevate the ratio of partial pressure of arterial O2 to fraction of inspired O2 (PaO2/FIO2 ratio). Additionally, PDE4B deletion reduced LPS-induced vascular permeability. Collectively, our results strongly indicates that PDE4B is a valid target for anti-ALI.

Breath pentane as a potential biomarker for survival in hepatic ischemia and reperfusion injury--a pilot study.

BACKGROUND: Exhaled pentane, which is produced as a consequence of reactive oxygen species-mediated lipid peroxidation, is a marker of oxidative stress. Propofol is widely used as a hypnotic agent in intensive care units and the operating room. Moreover, this agent has been reported to inhibit lipid peroxidation by directly scavenging reactive oxygen species. In this study, using a porcine liver ischemia-reperfusion injury model, we have evaluated the hypothesis that high concentrations of breath pentane are related to adverse outcome and that propofol could reduce breath pentane and improve liver injury and outcome in swine in this situation. METHODOLOGY/PRINCIPAL FINDINGS: Twenty male swine were assigned to two groups: propofol (n = 10) and chloral hydrate groups (n = 10). Hepatic ischemia was induced by occluding the portal inflow vessels. Ischemia lasted for 30 min, followed by reperfusion for 360 min. Exhaled and blood pentane concentrations in the chloral hydrate group markedly increased 1 min after reperfusion and then decreased to baseline. Breath and blood pentane concentrations in the propofol group increased 1 min after reperfusion but were significantly lower than in the chloral hydrate group. A negative correlation was found between breath pentane levels and survival in the chloral hydrate group. The median overall survival was 251 min after reperfusion (range 150-360 min) in the chloral hydrate group. All of the swine were alive in the propofol group. CONCLUSIONS: Monitoring of exhaled pentane may be useful for evaluating the severity of hepatic ischemia-reperfusion injury and aid in predicting the outcome; propofol may improve the outcome in this situation.

Sofnolime with different water content causes different effects in two sevoflurane inhalational induction techniques with respect to the output of compound-A.

OBJECTIVE: During sevoflurane anesthesia with Sofnolime for CO(2) absorption, the factors affecting the production of compound A (a chemical is nepherotoxic) are still not clear. This study is designed to investigate the effects of different fresh gas flow during induction, the vital capacity induction (VCI) vs. the tidal volume breath induction (TBI) on the compound-A production with a fresh Sofnolime or a dehydrated Sofnolime using a simulated lung model. METHOD: The experiments were randomly divided into four groups: group one, VCIf, vital capacity fresh gas inflow with fresh Sofnolime; group two, TBIf, tidal volume breath fresh gas inflow with fresh Sofnolime; group three, VCId, vital capacity fresh gas inflow with dehydrated Sofnolime, and group four, TBId, tidal volume breath fresh gas inflow with dehydrated Sofnolime. The inspired sevoflurane was maintained at 8%, the concentrations of compound-A were assayed using Gas-spectrum technique, and Sofnolime temperatures were monitored at 1-min intervals throughout the experiment. RESULTS: The mean and maximum concentrations of compound A were significantly higher in the vital capacity group than the tidal volume breath group (P<0.01). At the beginning of anesthesia maintenance, the compound-A concentration in group VCIf was 36.28±6.13 ppm, which was significantly higher than the 27.32±4.21 ppm observed in group TBIf (P<0.01). However, these values decreased to approximately 2 ppm in the dehydrated Sofnolime groups. Sofnolime temperatures increased rapidly in the dehydrated Sofnolime groups but slowly in the fresh Sofnolime groups. CONCLUSION: With fresh Sofnolime, vital capacity induction increased compound-A production in the circuit system compared with tidal volume breath induction. However, with dehydrated Sofnolime, the effects of the two inhalation induction techniques on compound-A output were not significantly different.

Measurement of pentane in expiratory gas during rabbit hepatic ischemia/ reperfusion by solid-phase microextraction and gas chromatography­mass spectrometry (SPME GC/MS).

The aim of this study was to determine the changes in the pentane concentration of expiratory gas as well as the relationship between this pentane concentration and hepatic oxidative stress during rabbit hepatic ischemia/reperfusion using solid-phase microextraction (SPME) and gas chromatography­mass spectrometry (GC/MS). 45 white male rabbits with body weights between 2.5 and 3.0 kg were randomly assigned to the following three groups: the 10 min ischemia group (group S); the 20 min ischemia group (group M); or the 30 min ischemia group(group L). Expiratory gases were collected prior to ischemia (T0) and for 1, 10, 20, 30, 60 and 120 min (T1­T6) following reperfusion. Pentane concentrations were determined using SPME and GC/MS. In addition, arterial blood samples were collected, and serum aminotransferase(AST) and malondialdehyde (MDA) concentrations were measured. In the three groups, the pentane concentrations of the expiratory gases at points T1 and T2 were significantly increased(P < 0.05) compared with those at point T0, and the serum AST and MDA concentrations at points T5 and T6 were also significantly increased (P < 0.05) compared with those at point T0.Therefore, the use of SPME in combination with GC/MS represents an improved anesthesia system that can be used to continuously measure the concentration of pentane in expiratory gases, which can reflect the degree of oxidative stress during hepatic ischemia/reperfusion.

Degradation products of different water content sevoflurane in carbon dioxide absorbents by gas chromatography-mass spectrometry analysis.

BACKGROUND: Sevoflurane is currently used as a volatile inhalation anesthetic with many clinical advantages. A representative degradation product, compound A, was quantitatively measured to investigate whether there are different reactions between two kinds of water content sevoflurane formulations with different carbon dioxide (CO2) absorbents. METHODS: A closed-circle breathe bag with the Dräger Fabius GS anesthesia apparatus was used as an artificial rubber lung. The experiments were grouped according to different sevoflurane formulations: group A: higher-water sevoflurane (Ultane); group B: lower-water sevoflurane (Sevoness). During the experiment, CO2 (200 ml/min) was continually perfused to keep the end-tidal pressure of CO2 (P(ET)CO2) at 35 - 45 mmHg. The artificial ventilation was set to 6 L/min, and the breathing rate at 12 breaths/min. The circuit was operated with constant fresh gas flow rate (1 L/min) and the sevoflurane concentration was kept at 1.0 minimum alveolar concentration (MAC) for 240 minutes. At 0, 10, 20, 30, 60, 90, 120, 180 and 240 minutes, gas was collected from the Y-piece. Gas chromatography/mass spectrometry (GC/MS) was used to quantify the major degradation product, compound A, with different water content sevoflurane. PETCO2 and sevoflurane concentration, and the temperature of the canister were continuously monitored during the experiment. RESULTS: There were no significant differences in P(ET)CO2 and sevoflurane concentrations between the two groups. Drägersorb 800 plus produced the highest concentrations of compound A compared with other sodalimes, and Sevoness in Drägersorb 800 plus generated more compound A than Ultane (P < 0.05). There were significant differences in the peak and average compound A concentrations between Ultane and Sevoness with Drägersorb 800 plus (P < 0.05), while the compound A concentration produced by Sodasorb grase and sofonolime in the two groups showed no significant difference (P > 0.05). In the same group, the peak and average of compound A concentration produced by Sodasorb grase and sofonolime showed significant difference with Drägersorb 800 plus (P < 0.05). CONCLUSION: The water content of sevoflurane and potassium hydroxide in CO2 absorbent can influence compound A production.

A comparison between vital capacity induction and tidal breathing induction techniques for the induction of anesthesia and compound A production.

BACKGROUND: Vital capacity induction and tidal breathing induction are currently administered for inhalation induction of anesthesia with sevoflurane. The aim of this study was to compare them using sevoflurane with respect to induction time, complications of inhalation induction, and compound A production in adult patients. METHODS: Fifty-one women with American Society of Anesthesiologists physical status I-II undergoing mammary gland tumorectomy were randomly assigned to receive either vital capacity induction or tidal breathing induction with 8% sevoflurane at 6 L/min followed by laryngeal mask airway insertion. Induction times, complications of inhalation induction, and vital signs were recorded. Inspired concentrations of compound A were assayed and sofnolime temperatures were monitored at one-minute intervals after sevoflurane administration. RESULTS: The time to loss of eyelash reflex was significantly shorter with the vital capacity induction technique than with the tidal breathing induction technique ((43.8 ± 13.4) seconds vs. (70.8 ± 16.4) seconds, respectively; P < 0.01). Cardiovascular stability was similar in both groups. The incidence of complications was significantly less with the vital capacity induction technique than with the tidal breathing induction technique (7.7% vs. 32%, respectively; P < 0.01). However, the mean and maximum concentrations of compound A during induction were significantly higher in the vital capacity group than those in the tidal breathing group (P < 0.05); compound A concentration at the beginning of anesthesia maintenance was (40.73 ± 10.83) ppm in the vital capacity group and (29.45 ± 7.51) ppm in tidal breathing group (P = 0.019). CONCLUSION: For inhalation induction of anesthesia, the vital capacity induction was faster and produced fewer complications than that for tidal breathing induction, but increased compound A production in the circuit system.

Breath pentane: an indicator for early and continuous monitoring of lipid peroxidation in hepatic ischaemia-reperfusion injury.

BACKGROUND AND OBJECTIVE: Lipid peroxidation plays an important role during liver ischaemia-reperfusion injury. Pentane in breath is often used as an index of lipid peroxidation. We observed the changes in levels of breath pentane during the lipid peroxidation process caused by liver ischaemia-reperfusion injury. METHODS: Ten male swine were anaesthetized with chloral hydrate 0.3-0.5 g kg(-1) min(-1). Total hepatic ischaemia was induced by occluding the portal inflow vessels. Ischaemia lasted 30 min followed by reperfusion for 180 min. Breath samples were sampled from the anaesthesia circuit and blood samples were collected from the inferior vena cava. Pentane concentrations in breath and blood were quantified by means of solid phase microextraction and gas chromatography-mass spectrography technique. RESULTS: Exhaled pentane concentrations (means +/- SE) increased markedly after reperfusion for 1 min (244.13 +/- 33.3 pmol l(-1)) and decreased gradually to initial levels after reperfusion for 60 min. Blood pentane concentrations (means +/- SE) increased significantly after reperfusion for 1 min (333.46 +/- 63.05 pmol l(-1)) and then decreased to basal level. Breath pentane concentrations showed a correlation with blood (r = 0.709, P < 0.05). CONCLUSION: Breath pentane analysis could provide early, rapid, noninvasive and continuous assessment of lipid peroxidation during hepatic ischaemia-reperfusion injury.