All-in-one self-floating porous foams as robust heat-blocking layers for efficient photothermal conversion and solar desalination.

Solar-driven interfacial evaporation is a highly efficient and ecofriendly technology for producing freshwater. Herein, self-floating plasmon Ag/black TiO2/carbon porous layered foams (Ag-BTCFs) were demonstrated as efficient solar-thermal convectors using freeze-drying cast-molding and high-temperature surface hydrogenation strategies. This all-in-one three-dimensional (3D) cross-linked self-floating porous layered foam material with full-spectrum absorption can fully harvest sunlight (∼95.45%) and effectively block heat transfer to its sublayer. The synergy of sufficient utilization of absorbed ultraviolet radiation by black TiO2 (b-TiO2), visible light absorption by Ag nanoparticles (Ag NPs) via localized surface plasmon resonance, and near-infrared absorption by layered-amorphous carbon can achieve full-solar-spectrum absorption to concentrate thermal energy. In addition to their synergistic effect, they are conducive to the relaxation of hot electrons when utilizing photogenerated holes to degrade pollutants in domestic wastewater. The steam generation efficiency of Ag-BTCFs is up to 1.79 kg m-2h-1 due to their solar energy conversion efficiency of 81.74% under 1 sun irradiation, which is five times higher than the evaporation rate of pure water. Notably, the material's efficient ion removal rate of 99.80% for solar desalination indicates its high potential for various applications. This strategy provides new insights for fabricating recyclable heat-blocking layer systems against thermal loss to enhance solar steam generation.

Polydopamine/defective ultrathin mesoporous graphitic carbon nitride nanosheets as Z-scheme organic assembly for robust photothermal-photocatalytic performance.

Polydopamine/defective ultrathin mesoporous graphitic carbon nitride (PDA/DCN) Z-scheme organic assembly is fabricated through high-temperature surface hydrogenation and ultrasonic freeze-dried strategies. PDA could be anchored on the surface of DCN with adequate N-vacancy defects firmly via π-π interactions, forming Z-scheme heterogenous structure for promoting charge separation. The visible and near-infrared light driven photocatalytic hydrogen evolution rate is up to 3420 µmol h-1 g-1, and the removal ratio of organic contaminant methylene blue is up to 98% within 70 min, which is several times higher than that of pristine graphitic carbon nitride and DCN. The important reason is the defects of DCN not only enhance the interaction with PDA, but also make the obvious polarized inbuilt electric field, and lead to Z-scheme structure for effective charge separation and rapid transfer, which is also confirmed by density functional theory (DFT) calculations. In addition, PDA extends the photoresponse to the near-infrared region and induces obvious photothermal effect to increase the reaction rate of the photocatalytic system. The efficient photothermal conversion of PDA/DCN should be another reason for the enhanced photocatalytic performance.

Surface hybridization of π-conjugate structure cyclized polyacrylonitrile and radial microsphere shaped TiO2 for reducing U(VI) to U(IV).

It is still a challenge to obtain uranium (U) adsorbents with high selectivity, excellent cycle stability and excellent performance through design and synthesis. In this paper, the TiO2/CPAN-AO catalyst was prepared by the hydrothermal method combined with high temperature cyclization dehydrogenation. TiO2/CPAN-AO has excellent photocatalytic properties, which can reduce U(VI) to U(IV) quickly and selectively. The generated Z-type heterojunction promotes the reduction ability of photogenerated electrons, and obtains great selectivity to UO22+ (Uranyl ions) through the AO group. TiO2/CPAN-AO with π-electron conjugated structure broadens the spectral range through surface hybridization and prolongs the lifetime of photo-generated charges. Under the induction of light, the uranium extraction capacity of TiO2/CPAN-AO after 5 h of irradiation is about 2.38 g/g. TiO2/CPAN-AO is a catalyst with enhanced adsorption capacity, making it possible to extract uranium from large-scale natural seawater in the future.

The Effect of Light Sedation with Midazolam on Functional Connectivity of the Dorsal Attention Network.

Altered connectivity within and between the resting-state networks (RSNs) brought about by anesthetics that induce altered consciousness remains incompletely understood. It is known that the dorsal attention network (DAN) and its anticorrelations with other RSNs have been implicated in consciousness. However, the role of DAN-related functional patterns in drug-induced sedative effects is less clear. In the current study, we investigated altered functional connectivity of the DAN during midazolam-induced light sedation. In a placebo-controlled and within-subjects experimental study, fourteen healthy volunteers received midazolam or saline with a 1-week interval. Resting-state fMRI data were acquired before and after intravenous drug administration. A multiple region of interest-driven analysis was employed to investigate connectivity within and between RSNs. It was found that functional connectivity was significantly decreased by midazolam injection in two regions located in the left inferior parietal lobule and the left middle temporal area within the DAN as compared with the saline condition. We also identified three clusters in anticorrelation between the DAN and other RSNs for the interaction effect, which included the left medial prefrontal cortex, the right superior temporal gyrus, and the right superior frontal gyrus. Connectivity between all regions and DAN was significantly decreased by midazolam injection. The sensorimotor network was minimally affected. Midazolam decreased functional connectivity of the dorsal attention network. These findings advance the understanding of the neural mechanism of sedation, and such functional patterns might have clinical implications in other medical conditions related to patients with cognitive impairment.

Surface-oxygen vacancy defect-promoted electron-hole separation of defective tungsten trioxide ultrathin nanosheets and their enhanced solar-driven photocatalytic performance.

Defective WO3 ultrathin surface-engineered nanosheets are fabricated by a solvothermal and low-temperature surface hydrogenation reduction strategy. The obtained defective WO3 ultrathin nanosheets with thicknesses of ∼4 nm possess a relatively large surface area of ∼25 m2 g-1. After surface engineering, the bandgap is narrowed to ∼2.48 eV due to the presence of surface oxygen vacancies, which further enhance the visible light absorption. The defective WO3 ultrathin nanosheets exhibit excellent solar-driven photocatalytic degradation performance for the complete degradation of the highly-toxic metribuzin herbicide (∼100%). The first-order rate constant (k) of the defective WO3 ultrathin nanosheets is ∼3 times higher than that of the pristine one. This can be ascribed to the formation of suitable surface-oxygen vacancy defects that promote the separation of photogenerated electron-hole pairs, and the two-dimensional ultrathin structure facilitating the surface engineering as well as furnishing a large number of surface active sites. Moreover, the defective WO3 ultrathin nanosheets exhibit high stability because the photocatalytic activity remains almost unchanged after 10 cycles, making them favorable for practical applications. This work offers new insights into the fabrication of other high-performance ultrathin nanosheet oxide photocatalysts for environmental applications.

Improved charge separation of NiS nanoparticles modified defect-engineered black TiO2 hollow nanotubes for boosting solar-driven photocatalytic H2 evolution.

NiS nanoparticles modified black TiO2 hollow nanotubes (NBTNs) are successfully synthesized via surface hydrogenation and the facile solvothermal method. The unique structure with intensified surface and interface characteristics endow NBTNs with more catalytic sites, and increase charge carrier separation efficiency with an extended charge lifetime, overwhelmingly promoting its photocatalytic performance. The resultant NBTNs possess a relatively high surface area and pore size of ∼89 m2 g-1 and ∼9.8 nm, respectively. The resultant NBTNs exhibit an excellent solar-driven photocatalytic hydrogen rate (3.17 mmol h-1 g-1), which is almost as high as that of Pt as cocatalyst, in which the apparent quantum yield of 5.4% (420 nm) is recorded for the NBTNs sample. Moreover, the turnover number can be up to 116 000 within 48 h and the turnover frequency is 2400 for NiS. This novel strategy could provide a better understanding of cocatalyst photocatalytic mechanisms, and a scheme simultaneously regulating the morphology and structure of photocatalysts for promoting H2 generation.

Plasmon Ag-Promoted Solar-Thermal Conversion on Floating Carbon Cloth for Seawater Desalination and Sewage Disposal.

Using solar energy to achieve seawater desalination and sewage disposal has received tremendous attention for its potential possibility to produce clean freshwater. However, the low solar-thermal conversion efficiency for solar absorber materials obstacles their practical applications. Herein, Ag nanoparticles modified floating carbon cloth (ANCC) are first synthesized via wet impregnation, photoreduction, and low-temperature drying strategy, which could float on the water and absorb the solar energy efficiently. It is worth noting that vaporization rate of ANCC with a high wide-spectrum absorption (92.39%) for the entire range of optical spectrum (200-2500 nm) is up to 1.36 kg h-1 m-2 under AM 1.5, which corresponds to solar-thermal conversion efficiency of ∼92.82% with superior seawater desalination and sewage disposal performance. Plasmon Ag promotes the conversion efficiency obviously compared to the pristine carbon cloth because the surface plasmon resonance effect could increase the local temperature greatly. After the desalination, the ion concentrations (Mg2+, K+, Ca2+, and Na+ ions) in water are far below the limit of drinking water. Such high-performance floating ANCC material may offer a feasible and paradigm strategy to manage the global water contamination and freshwater shortage problem.

A new air- and moisture-stable pentagonal-bipyramidal DyIII single-ion magnet based on the HMPA ligand.

Based on the HMPA ligand, a new air- and moisture-stable pentagonal-bipyramidal DyIII single-ion magnet [Dy(HMPA)2(H2O)5]2·Br6·2HMPA·2H2O (1) was prepared and characterized. Single-crystal X-ray tests showed the two crystallographically independent DyIII ions located in a pentagonal-bipyramidal coordination sphere with strong axial HMPA ligands and weak equatorial water molecules relating to strong unaxial anisotropy. Direct-current and alternating-current magnetic susceptibilities were measured and showed that 1 exhibited slow relaxation of magnetization up to 36 K (1000 Hz) with an energy barrier of 556 K and blocking temperature of 7 K (defined by the peak temperature of zero-field cooling data). The application of a dc field and magnetic dilution were also carried out to explore the existing quantum tunelling of the magnetization process.

Homojunction and defect synergy-mediated electron-hole separation for solar-driven mesoporous rutile/anatase TiO2 microsphere photocatalysts.

The photocatalytic hydrogen evolution of TiO2 is deemed to be one of the most promising ways of converting solar energy to chemical energy; however, it is a challenge to improve the photo-generated charge separation efficiency and enhance solar utilization. Herein, black mesoporous rutile/anatase TiO2 microspheres with a homojunction and surface defects have been successfully synthesized by an evaporation-induced self-assembly, solvothermal and high-temperature surface hydrogenation method. The H500-BMR/ATM (HX-BMR/ATM, where X means the different hydrogen calcination temperatures) materials not only possess a mesoporous structure and relatively high specific surface area of 39.2 m2 g-1, but also have a narrow bandgap (∼2.87 eV), which could extend the photoresponse to the visible light region. They exhibit high photocatalytic hydrogen production (6.4 mmol h-1 g-1), which is much higher (approximately 1.8 times) than that of pristine mesoporous rutile/anatase TiO2 microspheres (3.58 mmol h-1 g-1). This enhanced photocatalytic hydrogen production property is attributed to the synergistic effect of the homojunction and surface defects in improving efficient electron-hole separation and high utilization of solar light. This work proposes a new approach to improve the performance of photocatalytic hydrogen production and probably offers a new insight into fabricating other high-performance photocatalysts.

Surface defect-mediated efficient electron-hole separation in hierarchical flower-like bismuth molybdate hollow spheres for enhanced visible-light-driven photocatalytic performance.

It is desirable to develop an efficient visible-light-driven photocatalyst for practical application to degrade highly-noxious pollutants. Herein, the hydrogenation hierarchical flower-like Bi2MoO6 hollow spheres (H-BMO-X, where X represents the different hydrogen calcination temperatures) have been successfully fabricated by a solvothermal-surface hydrogenation process. The as-prepared nano-photocatalyst H-BMO-300 clearly exhibits a photocatalytic reaction apparent rate constant k for high-noxious pollutants by ∼3-times higher than pristine Bi2MoO6. Moreover, the resultant H-BMO-300 sample with a narrow bandgap of ∼2.70 eV possesses surface oxygen vacancy defects. Based on the scanning Kelvin probe and surface photovoltage spectroscopy, it is deduced that the photocatalytic activities are attributed to the surface oxygen vacancy of H-BMO-X favoring the electron-hole pair's separation. The enhanced photocatalytic performance can be ascribed to the synergistic effect of surface defects favoring efficient electron-hole separation and the hollow hierarchical structure benefiting the utilization of visible light, which provides more surface-active sites. This work provides a viable route to perceptibly enhance the photocatalytic activities of H-BMO-300 for environmental remediation with good mineralization properties.

Decreased Cerebral Blood Flow in Mesial Thalamus and Precuneus/PCC during Midazolam Induced Sedation Assessed with ASL.

While some previous work suggests that midazolam-induced light sedation results from the functional disconnection within resting state network, little is known about the underlying alterations of cerebral blood flow (CBF) associated with its effects. A randomized, double-blind, within-subject, cross-over design was adopted, while 12 healthy young volunteers were scanned with arterial spin-labeling (ASL) perfusion MRI both before and after an injection of either saline or midazolam. The contrast of MRI signal before and after midazolam administration revealed the CBF decrease in the bilateral mesial thalamus and precuneus/posterior cingulate cortex (PCC). These effects were confirmed after controlling for any effect of injection as well as head motions. These findings provide new evidences that midazolam-induced light sedation is related to the disruption of cortical functional integration, and have new implications to the neural basis of consciousness.

Non-Conjugated Polymer as an Efficient Dopant-Free Hole-Transporting Material for Perovskite Solar Cells.

A new non-conjugated polymer (PVCz-OMeDAD) with good solution processability was developed to serve as an efficient dopant-free hole-transporting material (HTM) for perovskite solar cells (PSCs). PVCz-OMeDAD was simply prepared by the free-radical polymerization of vinyl monomers, which were synthesized from low-cost raw materials through three high-yield synthesis steps. The combination of the flexible non-conjugated polyvinyl main chain and hole-transporting methoxydiphenylamine-substituted carbazole side chains endowed PVCz-OMeDAD with excellent film-forming ability, a suitable energy level, and high hole mobility. As a result, by using an ultra-thin (≈30 nm) PVCz-OMeDAD film as cost-effective dopant-free polymer HTM, the conventional n-i-p-type PSCs demonstrated a power conversion efficiency (PCE) up to 16.09 %, suggesting the great potential of the polymer film for future low-cost, large-scale, flexible PSCs applications.

Disruption of cortical integration during midazolam-induced light sedation.

This work examines the effect of midazolam-induced light sedation on intrinsic functional connectivity of human brain, using a randomized, double-blind, placebo-controlled, cross-over, within-subject design. Fourteen healthy young subjects were enrolled and midazolam (0.03 mg/kg of the participant's body mass, to a maximum of 2.5 mg) or saline were administrated with an interval of one week. Resting-state fMRI was conducted before and after administration for each subject. We focus on two types of networks: sensory related lower-level functional networks and higher-order functions related ones. Independent component analysis (ICA) was used to identify these resting-state functional networks. We hypothesize that the sensory (visual, auditory, and sensorimotor) related networks will be intact under midazolam-induced light sedation while the higher-order (default mode, executive control, salience networks, etc.) networks will be functionally disconnected. It was found that the functional integrity of the lower-level networks was maintained, while that of the higher-level networks was significantly disrupted by light sedation. The within-network connectivity of the two types of networks was differently affected in terms of direction and extent. These findings provide direct evidence that higher-order cognitive functions including memory, attention, executive function, and language were impaired prior to lower-level sensory responses during sedation. Our result also lends support to the information integration model of consciousness.

κ-Opioid receptors are involved in enhanced cardioprotection by combined fentanyl and limb remote ischemic postconditioning.

BACKGROUND: The combination of various interventions to obtain enhanced cardioprotection is always an important area of research focus. This randomized experiment was designed to assess whether combined fentanyl and limb remote ischemic postconditioning produced enhanced protection against myocardial ischemia/reperfusion injury in an in vivo rat model, and to determine if κ-opioid receptors were implicated in the cardioprotection of these interventions. METHODS: Seventy-two rats were exposed to a 30-min myocardial ischemia followed by a 180-min reperfusion. Half of the rats (36) were randomized into four different groups receiving control treatment, fentanyl postconditioning, limb remote ischemic postconditioning, and combined fentanyl and limb remote ischemic postconditioning. The remaining 36 rats were also randomized into four groups receiving the same interventions as the above groups following the intravenous administration of a κ-opioid receptor antagonist, nor-binaltorphimine, before myocardial ischemia. At the end of reperfusion, both serum cardiac troponin I and infarct size were determined. RESULTS: Both fentanyl postconditioning and limb remote ischemic postconditioning significantly decreased the infarct size and serum cardiac troponin I level, and combined fentanyl and limb remote ischemic postconditioning produced enhanced cardioprotection on the infarct size-sparing effect. The use of nor-binaltorphimin to block κ-opioid receptors eliminated cardioprotection by fentanyl postconditioning and enhanced cardioprotection by combined fentanyl and limb remote ischemic postconditioning, but did not change cardioprotection by limb remote ischemic postconditioning. CONCLUSIONS: Combined fentanyl and limb remote ischemic postconditioning produced enhanced protection against myocardial ischemia/reperfusion injury. κ-Opioid receptors are essential for cardioprotection by fentanyl postconditioning and enhanced cardioprotection by combined fentanyl and limb remote ischemic postconditioning; however, they do not play a pivotal role in cardioprotection by limb remote ischemic postconditioning.

[Effects of combined ischemic postconditioning, remote ischemic postconditioning and naloxone postconditioning on focal cerebral ischemia-reperfusion injury in rats].

OBJECTIVE: To assess the effects of ischemic postconditioning, remote ischemic postconditioning and naloxone postconditioning on focal cerebral ischemia-reperfusion injury in rats. METHODS: A total of 110 adult SD rats were randomly divided into 5 groups (n = 22 each). The focal cerebral ischemia-reperfusion injury was induced by a 90-minute occlusion of right middle cerebral artery (MCA) and a 24-hour reperfusion sequentially. Group 1 was of ischemia-reperfusion control; Group 2 ischemic postconditioning induced by three 30-second cycles of MCA occlusion followed by a 30-second reperfusion; Group 3 remote ischemic postconditioning performed via a transient occlusion of right femoral artery at 5 min before the initiation of reperfusion; Group 4 naloxone postconditioning with naloxone 10 mg/kg intraperitoneally injected at the initiation of reperfusion; Group 5 combined ischemic, remote ischemic & naloxone postconditioning performed simultaneously in accordance with the methods used in Groups 2, 3 & 4. The neurologic deficit scores (NDS) were obtained at 2 h & 24 h post-reperfusion. At 24 h post-reperfusion, the anesthetized rat was sacrificed by decapitation and the brain rapidly extracted to assess the size of cerebral infarct (n = 10), detect the cerebral expression of microtubule-associated protein-2 (MAP2) (n = 6), measure the plasma volume of cerebral tissues and quantify the diameter and segment length of cerebral microvessel (n = 6). RESULTS: There were no significant differences in the heart rate (HR) and mean arterial pressure (MAP) among the above five groups at all observed time points (P > 0.05). At 24 h post-reperfusion, the percentage of ischemic cerebral infarct size was 43% ± 6%, 31% ± 4%, 32% ± 5%, 28% ± 6% & 21% ± 7% in ipsilateral hemisphere area (i.e., cerebral infarct severity) in Groups 1-5 respectively. Compared with Group 1, the levels of NDS and cerebral infarct severity significantly decreased at ischemic side in Groups 2-5 (P < 0.05). And the cerebral expression of MAP2, plasma volume of cerebral tissues, diameter and segment length of cerebral microvessel significantly increased at the ischemic side (all P < 0.05). However, there were no significant differences in the above-mentioned parameters at ischemic side among Groups 2, 3 and 4 (all P > 0.05). The parameters of NDS, cerebral infarct severity, cerebral expression of MAP2 and plasma volume of cerebral tissues in the ischemic side significantly increased in Group 5 compared with Groups 1, 2, 3 and 4 (all P < 0.05). The diameter and segment length of cerebral microvessel at ischemic side were not different among Groups 2, 3, 4 and 5 (all P > 0.05). CONCLUSION: In focal cerebral ischemia-reperfusion rats, ischemic, remote ischemic and naloxone postconditioning may produce significant neuroprotective effects of reduced cerebral infarct severity and improved neurologic dysfunctions. A combination of three postconditioning approaches enhances the above neuroprotective effects.

[Effect of remifentanil preconditioning on myocardial ischemia-reperfusion injury].

OBJECTIVE: To investigate the delayed cardioprotection induced by remifentanil in intact rat ischemia-reperfusion (I/R) models. METHODS: Totally 42 adult male Wistar rats weighing 200-300 g were randomly divided into 7 groups (n = 6 in each group): In Group I, rats were injected with normal saline via tail vein, performed with the regimen of 3 x 5-min intravenous (i.v.) infusion at a rate of 0.1 ml x kg(-1) min(-1) 24 h before I/R; In Group II, rats were treated according to the same experimental protocols as in Group I except receiving additional naloxone (0.1 mg/kg) 10 minutes before normal saline pretreatment; In Groups III, IV, V, and VI, rats were treated with remifentanil via tail vein, performed with the regime of 3 x 5-min i.v. infusion at a rate of 2 microg x kg(-1) x min(-1) 12 h, 24 h, 48 h, and 72 h before I/R; In Group VII, the rats were treated according to the same experimental protocols as in Group IV except that they received additional naloxone (0.1 mg/kg) 10 minutes before remifentanil pretreatment. Heart rate (HR), mean arterial pressure (MAP), and a lead II electrocardiogram were continuously monitored during IR process. To determine plasma concentration of creatine kinase myocardial isoenzyme-MB (CK-MB), arterial blood samples were obtained immediately before ischemia, and at the end of ischemia and reperfusion. After a 120-min reperfusion, heart was removed for the measurement of myocardial infarct size. Infarct size (IS) was expressed as percentage of the area at risk. RESULTS: HR, MAP, and rate-pressure product were not significantly different at each time points among all groups (P > 0.05). Compared with Group I, plasma concentrations of CK-MB at the end of ischemia and reperfusion and myocardial infarct size were significantly lower in Groups IV and V (P < 0.05). Compared with Group IV, plasma concentrations of CK-MB at the end of ischemia and reperfusion were significantly higher and myocardial infarct size was significantly larger in Group VII (P < 0.05). CONCLUSION: Remifentanil preconditioning induces delayed cardioprotection in intact rat ischemia-reperfusion model, which may be triggered via opioid receptors.

Median effective dose of remifentanil for awake laryngoscopy and intubation.

BACKGROUND: Awake intubation requires an anesthetic management that provides sufficient patient safety and comfort, adequate intubating conditions, and stable hemodynamics. In this prospective clinical study, our aim was to determine the median effective dose (ED(50)) of remifentanil in combination with midazolam and airway topical anesthesia for awake laryngoscopy and intubation. METHODS: Thirty-six female adult patients, scheduled for elective plastic surgery under general anesthesia requiring orotracheal intubation were included in this study. Ten minutes after intravenous administration of midazolam 0.1 mg/kg, patients were assigned to receive remifentanil in bolus, followed by a continuous infusion. The bolus dose and infusion rate of remifentanil were adjusted by a modified Dixon's up-and-down method. Patient's reaction score at laryngoscopy and an Observer's Assessment of Alertness/Sedation Scale (OAA/S) were used to determine whether the remifentanil dosage regimen was accepted. During laryngoscopy, 2% lidocaine was sprayed into the airway to provide the topical anesthesia. ED(50) of remifentanil was calculated by the modified Dixon up-and-down method, and the probit analysis was then used to confirm the results obtained from the modified Dixon's up-and-down method. In the patients who were scored as "accept", patient's OAA/S and reaction scores at different observed points, intubating condition score and patient's tolerance to the endotracheal tube after intubation were evaluated and recorded. Blood pressure and heart rate at different measuring points were also noted. RESULTS: ED(50) of remifentanil for awake laryngoscopy and intubation obtained by the modified Dixon's up-and-down method was (0.62 +/- 0.02) microg/kg. Using probit analysis, ED(50) and ED(95) of remifentanil were 0.63 microg/kg (95% CI, 0.54 - 0.70) and 0.83 microg/kg (95% CI, 0.73 - 2.59), respectively. Nineteen patients who were scored as "accept" had an OAA/S of > 15 and tolerated well laryngoscopy without significant discomfort or gagging. The mean intubating condition score was 1.8 +/- 0.8. The endotracheal tube was well tolerated. During awake laryngoscopy and intubation, blood pressure and heart rate were also kept stable. The postoperative follow up showed that no patient recalled discomfort and pain for airway manipulation. CONCLUSIONS: When combined with midazolam 0.1 mg/kg and airway topical anesthesia, ED(50) of remifentanil for successful awake laryngoscopy and intubation is 0.62 microg/kg in bolus followed by continuous infusion of 0.062 microg*kg(-1)*min(-1). This sedation and analgesia regimen can provide patient safety and comfort, ensure adequate intubating conditions, maintain hemodynamic stability, and prevent negative recall of the airway procedure.

Clinical assessment of awake endotracheal intubation using the lightwand technique alone in patients with difficult airways.

BACKGROUND: There is few study to determine whether the use of the lightwand technique alone could achieve effective, safe and successful awake endotracheal intubation (ETI), therefore we designed a prospective clinical study to systematically evaluate the feasibility, safety and efficacy of awake ETI using the lightwand alone in patients with difficult airways. METHODS: Seventy adult patients with difficult airways were enrolled in this study. After the desired sedation with fentanyl and midazolam, airway topical anesthesia was performed with 9 ml of 2% lidocaine, which were in order sprayed in three aliquots at 5 minutes intervals into the supraglottic (two doses) and laryngotracheal areas (one dose) using a combined unit of the lightwand and MADgic atomizer. After airway topical anesthesia, awake ETI was performed using a Lightwand. Subjective assessments by patients and operators using the visual analogue scores (VAS), and objective assessments by an independent investigator using patients' tolerance and reaction scores, coughing severity, intubating conditions and cardiovascular variables were taken as the observed parameters. RESULTS: Of 210 airway sprays, 197 (93.8%) were successfully completed on the first attempt. The total time for airway spray was (14.6 +/- 1.5) minutes. During airway topical anesthesia, the average patients' tolerance scores were 1.7 - 2.3. After airway topical anesthesia, the mean VAS for discomfort levels that the patients reported was 6.5. Also airway topical anesthesia procedure was rated as acceptable and no discomfort by 94.3% of patients. The lightwand-guided awake ETI was successfully completed on first attempt within 29 seconds in all patients. During awake ETI, patients' reaction and coughing scores were 1.9 and 1.6, respectively. All patients exhibited excellent or acceptable intubating conditions. Cardiovascular monitoring revealed that changes of systolic blood pressure and heart rate at each stage of airway manipulations were less than 20% of baseline values. The postoperative follow-up showed that 95.7% of patients had no recall or slight memories of all airway instrumentation. The incidence of postoperative mild airway complications was 38.6%. CONCLUSION: Alone use of the lightwand technique can achieve effective, safe and successful awake ETI in patients with difficult airways.

Comparison of bolus remifentanil versus bolus fentanyl for blunting cardiovascular intubation responses in children: a randomized, double-blind study.

BACKGROUND: The authors found no study to compare the efficacy of bolus dose fentanyl and remifentanil blunting the cardiovascular intubation response in children, so they designed this randomized, double-blind clinical study to assess the effects of remifentanil 2 microg/kg and fentanyl 2 microg/kg by bolus injection on the cardiovascular intubation response in healthy children. METHODS: One hundred and two children, the American Society of Anesthesiologists (ASA) physical status 1-2 and scheduled for elective plastic surgery under general anesthesia, were randomly divided into one of two groups to receive the following treatments in a double blind manner: remifentanil 2 microg/kg (Group R) and fentanyl 2 microg/kg (Group F) when anesthesia was induced with propofol and vecuronium. The orotracheal intubation was performed using a direct laryngoscope. Blood pressure (BP) and heart rate (HR) were recorded before anesthesia induction (baseline values), immediately before intubation, at intubation and every minute for 5 minutes after intubation. The percent changes of systolic blood pressure (SBP) and HR relative to baseline values and the rate pressure product (RPP) at every observing point were calculated. The incidences of SBP and HR percent changes >30% of baseline values and RPP >22,000 during the observation were recorded. RESULTS: There were no significant differences between groups in the demographic data, baseline values of BP and HR and the intubation time. As compared to baseline values, BP, HR and RPP at intubation and their maximum values during observation increased significantly in Group F, but they all decreased significantly in Group R. BP, HR and RPP at all observed points, and their maximum values during the observation, were significantly different between groups. There were also significant differences between groups in the percent change of SBP and HR relative to baseline values at all observed points and their maximum percent changes during the observation. The incidences of SBP and HR percent increased >30% of the baseline values and RPP >22,000 during the observation, were significantly higher in Group F than in Group R, but the incidences of SBP and HR percent decreased >30% of baseline values were significantly lower in Group F compared with Group R. CONCLUSIONS: When used as part of routine anesthesia induction with propofol and vecuronium in children, fentanyl 2 microg/kg by bolus injection fails to effectively depress the cardiovascular intubation response. Remifentanil 2 microg/kg by bolus injection can completely abolish the cardiovascular intubation response, but also cause more adverse complications of temporary significant cardiovascular depression.