Effect of sulfur doping of zinc-imidazole coordination polymer (ZnIm CP) as a novel photocatalyst for degradation of ionic dyes

Zinc-Imidazole coordination polymer (ZnImCP) was simply synthesized hydrothermally at relatively low temperature (70 °C) from zinc acetate and imidazole. ZnImCP was treated by sulfide solution to produce sulfur-doped samples (S-ZnImCPs). Structures of the synthesized ZnImCP and S-ZnImCPs were characterized through FTIR, PXRD, and, Raman, SEM/EDX, N2-BET, UV–VIS DRS, and pHpzc analyses. The photocatalytic performances of pristine CP and sulfur modified CPs under visible and ultra-violet irradiations for degrading the cationic methylene blue (MB) and the anionic methyl orange (MO) were investigated considering different initial pH values 4, 7 and 10. Under visible light, the results indicate that these CPs display considerable photocatalytic degradation towards the cationic MB for the initial pH 4 and 7 where degradation increases with sulfur content. While under ultra-violet, results indicate considerable photocatalytic degradation towards both dyes for the initial pH 7 and 10 where degradation increases with sulfur content which indicates the gainful of non-metal dopping. The buffering nature of CPs and the type of radiation considering determined band-gap values effectively influence the degradation mechanisms.

Activation of Cadmium–Imidazole Buffering Coordination Polymer by Sulfur-Doping for the Enhancement of Photocatalytic Degradation of Cationic and Anionic Dyes Under Visible Light

The buffering Cadmium–Imidazole Coordination Polymer (Cd–Im-CP) was synthesized hydrothermally from cadmium chloride and imidazole at 70 °C and then was subjected to doping- by the non-metal sulfur using Na2S solution as a novel modification strategy to produce S–Cd–Im CPs. To investigate doping nature and its effects, Cd–Im CP and S–Cd–Im CPs were characterized applying different analyses techniques, FTIR, Raman, PXRD, SEM/EDX, TGA, and UV–Vis DRS analyses. Characterizations showed the successful chemical doping of sulfur. The inclusion of sulfur within chemical CP structure caused narrowing of material’s bandgap from 4.55 and 3.4 eV to 4.25 and 2.35 eV for S–Cd–Im CPs allowing it for photoresponse towards Visible-light. Both Cd–Im CP and S–Cd–Im CPs were applied for photocatalytic degradation of the selected dyes methylene blue (MB),and methyl orange (MO) employing visible and UV irradiations considering three different initial pH levels to investigate the consequence of sulfur doping. After eliminating the photolysis effect, the best degradation by S–Cd–Im CPs was recorded for MB at initial pH 4 being 13 fold that is for Cd–Im CP. The highest apparent turnover frequencies are 1.2 × 10−3 h−1 for MB at initial pH 10 and 1.03 × 10−4 h−1 for MO at initial pH 4 are given by 10S–Cd–IM CP under Visible-light. Generally, S–Cd–Im CPs remarkably improved photocatalysis degradation of both the dyes for all initial pH levels under Visible-light.

Designing bimetallic zeolitic imidazolate frameworks (ZIFs) for aqueous catalysis: Co/Zn-ZIF-8 as a cyclic-durable catalyst for hydrogen peroxide oxidative decomposition of organic dyes in water

ZIF-8 is well known hybrid material that is self-assembled from inorganic and organic moieties. It has several potential applications due to its unique structure. One of these potential applications is in advanced oxidation processes (AOP) via a heterogeneous catalysis system. The use of modified ZIF-8/H2O2 for the destruction of the azo dye methyl orange (MO) is presented in this work to explore its efficacy. This work presents the bimetallic Co/Zn-ZIF-8 as an efficient catalyst to promote H2O2 oxidation of the MO dye. Co/Zn-ZIF-8 was synthesized through a hydrothermal process, and the pristine structure was confirmed using XRD, FTIR, and XPS. The Co/Zn-ZIF-8/H2O2 system successfully decolorized MO at the selected pH 6.5. It was found that more than 90% of MO (10 ppm) was degraded within only about 50 minutes. Proposed radical and redox mechanisms are presented for H2O2 decomposition where the redox mechanism is suggested to predominate via a Co(ii)/Co(iii) redox consecutive cyclic process.

Advances of the highly efficient and stable visible light active photocatalyst Zr(IV)-phthalate coordination polymer for the degradation of organic contaminants in water

This work presents the restoration of the Zr-phthalate coordination polymer (Zr-Ph CP) via valuable application in photocatalysis. Zr-Ph CP was facilely synthesized using a soft hydrothermal method at 70 °C, and was characterized utilizing FTIR, Raman Spectrosopy, XPS, PXRD, SEM/EDX, BET, and a hyperspectral camera. Assessment of its photocatalytic degradation potential was performed against two different dyes, the cationic methylene blue (MB) and the anionic methyl orange (MO), as frequent models of organic contaminants, under properly selected mild visible illumination (9 W) where the bandgap energy (Eg) was determined to be 2.72 eV. Effects of different initial pH values and different dyes' initial concentrations were covered. Photocatalytic degradation studies showed that Zr-Ph CP effectively degraded both dyes for initial pH 7 within about 40-60 minutes. Degradation rate constants were calculated as 0.17 and 0.13 min-1 for MB and MO, respectively. Generally, both direct and indirect mechanisms share in the degradation, where adsorption has shown an important role. The repeated use of Zr-Ph CP does not significantly affect its photocatalytic performance suggesting high water stability.

Synthesis of a novel Ce(iii)/melamine coordination polymer and its application for corrosion protection of AA2024 in NaCl solution

We present the synthesis of a new cerium(iii)-melamine coordination polymer (CMCP) by a mixed-solvothermal method and its characterization. Characterization techniques included Raman, Fourier Transformation Infra-Red (FTIR), X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM), in which the change in the electronic environment and the crystallinity were tracked. The characterization results confirm the coordination of cerium(iii) with melamine through -NH2 groups, instead of the N atoms of the triazine ring, for which we propose a mechanism of interaction. In addition, Biovia Materials Studio package was applied to determine and investigate the molecular structure of the CMCP. All simulations were done using COMPASS force-field theory and atom-based method for summation of electrostatic and van de Waals forces. The application of the CMCP for the corrosion inhibition of AA2024 in 3.5% NaCl solution was tested using the potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The results point out that the presence of cerium as cerium(iii) in the CMCP structure plays the fundamental role of inhibition, whereby the inhibition mechanism occurs by cathodic oxidation of Ce(iii) to Ce(iv) and cyclic reduction of Ce(iv) to Ce(iii) by melamine part of CMCP.

3D spectral fluorescence signature of cerium(III)-melamine coordination polymer: A novel sensing material for explosive detection

Hidden or buried explosives are the most common scenario by terrorist attacks; therefore explosive vapour detection is a vital demand. Explosives are electron deficient materials; the vicinity of explosives to fluorescent material can encounter electron migration. This study reports on facile synthesis of cerium (III)-melamine coordination polymer (CeM-CP) with exclusive optical properties. CeM-CP demonstrated novel spectral fluorescence properties over visible and infrared bands when stimulated with UVA LED source at 385 nm of 100 mW power. Stimulated CeM-CP demonstrated unique spectral fluorescence signal at 400, 700, and 785 nm. These fluorescent signals were correlated to cerium coordination with four nitrogen atoms; vacant orbital will be available for electron excitation migration. Spectral fluorescent signals were quenched as CeM-CP was subjected to TNT vapours. Hyperspectral imaging offered 3D plot of fluorescence signature. The main outcome is that complete fluorescence signal attenuation was achieved at 785 nm. CeM-CP could act as as a novel sensing element for explosive vapour detection.

Gum Arabic polymer-stabilized and Gamma rays-assisted synthesis of bimetallic silver-gold nanoparticles: Powerful antimicrobial and antibiofilm activities against pathogenic microbes isolated from diabetic foot patients

In this research, irradiation by gamma rays was employed as an eco-friendly route for the construction of bimetallic silver-gold nanoparticles (Ag-Au NPs), while Gum Arabic polymer was used as a capping agent. Ag-Au NPs were characterized through UV-Vis., XRD, EDX, HR-TEM, FTIR, SEM/mapping and EDX analysis. Antibiofilm and antimicrobial activities were examined against some bacteria and Candida sp. isolates from diabetic foot patients. Our results revealed that the synthesis of Ag-Au NPs depended on the concentrations of tetra-chloroauric acid and silver nitrate. HR-TEM analysis confirmed the spherical nature and an average diameter of 18.58 nm. FTIR results assured many functional groups in Gum Arabic which assisted in increasing the susceptibility of incorporation with Ag-Au NPs. Our results showed that, Ag-Au NPs exhibited the highest antimicrobial performance against B. subtilis (14.30 mm ZOI) followed by E. coli (12.50 mm ZOI) and C. tropicalis (11.90 mm ZOI). In addition, Ag-Au NPs were able to inhibit the biofilm formation by 99.64%, 94.15%, and 90.79% against B. subtilis, E. coli, and C. tropicalis, respectively. Consequently, based on the promising properties, they showed superior antimicrobial potential at low concentration and continued-phase durability, they can be extensively-used in many pharmaceutical and biomedical applications.

Initial absolute monocyte count as an immune biomarker for clinical response in acute myeloid leukemia with monocytic differentiation

BACKGROUND

Absolute monocyte count (AMC) correlates with survival outcomes in various hematologic malignancies. However, its role in myeloid malignancies including AML needs to be highlighted. So, this prospective cohort study aimed to assess the effect of AMC on the treatment outcome and survival in a 56 adult de novo AML patients with monocytic differentiation, admitted to the Clinical Hematology Unit, Internal Medicine Department, in a tertiary referral hospital in Egypt, from July 2016 to June 2019.

RESULTS

The initial AMC was measured either by manual differential or the hematology automatic analyzer Sysmex XN-2000 and patients were classified by using receiver operating characteristic curve into two groups monocytopenic (≤ 4 × 10⁹/L) and non-monocytopenic (> 4 × 10⁹/L) group; including 24 (42.9%) and 32 (57.1%) patients, respectively. After a median follow up period of 7.7 (range 0.5-33.2) months, the monocytopenic group was associated with a significantly higher CR rate (P = 0.019), with a lower death as well as relapse and early relapse rates (P = 0.011, 0.033, and 0.002, respectively). Moreover, low initial AMC along with intensive induction were independently associated with complete response to induction chemotherapy with HR, 5.04 [1.37-18.58], P = 0.015, and 5.67 [1.48-21.71], P = 0.011, respectively by using the multivariate logistic regression model. Regarding survival, the monocytopenic group was associated with a better 3-year disease-free survival rate (P = 0.011) in univariate Cox regression only but did not reach significance in the multivariate model and did not affect the overall survival as well.

CONCLUSION

Initial AMC was found to be an independent prognostic immune biomarker for treatment response in AML patients with monocytic differentiation. However, it did not appear as an independent predictor of survival in a multivariate analysis.

Corrosion protection mechanism of Ce4+/organic inhibitor for AA2024 in 3.5% NaCl

Cerium is a rare earth element that has been widely proposed for the corrosion protection of aluminium alloys (AA). Both cerium salts, Ce³⁺ and Ce⁴⁺, have been used in combination with other compounds to offer synergistic inhibition, however, the inhibitive corrosion mechanism when using Ce⁴⁺ with organic compounds is still not clear. In this study, the synergistic inhibition effect of Ce⁴⁺ and melamine (M) on the corrosion of aluminium alloy 2024 (AA2024) in 3.5% NaCl solution was investigated. Potentiodynamic Polarization (PDP) and Electrochemical Impedance Spectroscopy (EIS) techniques were used to study the synergistic effect of different Ce⁴⁺/M ratios on the corrosion behaviour of AA2024. The PDP study showed that a combination of 50% Ce⁴⁺ and 50% M leads to the lowest corrosion rates, both acting as cathodic inhibitors. Both PDP and EIS results indicated that M or Ce⁴⁺ in isolation did not offer effective corrosion protection, while the combination of M and Ce⁴⁺ significantly enhances the corrosion protection with a synergism parameter equal to 3.5. SEM and EDX observations confirm the findings from the electrochemical techniques. XPS was used to investigate the mechanism of protection, revealing that the reduction of Ce⁴⁺ to Ce³⁺ occurs during protection of AA2024. A new mechanism of corrosion synergistic inhibition by Ce⁴⁺ and organic compounds is postulated where the role of the organic compounds is to enhance the reduction of Ce⁴⁺.

Proposed corrosion protection mechanism of Ce⁴⁺/ organic inhibitor for AA2024.

Blood Ordering Habits for Elective Surgery: Time for Change

A prospective study was carried out for 6 months to determine the efficacy of blood ordering routines for elective surgery. It was found that only 23% of procedures needed preoperative crossmatching of blood (transfusion index ‘IT’ >0.5). There was an excessive over-ordering of blood for 77% of the operations (crossmatch/transfusion ratio >2.5). In addition, the transfusion index for the latter group showed that there was no need to prepare blood preoperatively (TI <0.5).

A transfusion tariff is worked out which abandons crossmatching for the majority of procedures (cholecystectomy, thyroidectomy and surgery for duodenal ulcer excluding gastrectomy). Instead a ‘group and screen’ policy is suggested.

Detection of minimal residual disease in childhood B-acute lymphoblastic leukemia by 4-color flowcytometry

Monitoring of minimal residual disease (MRD) is currently considered the most powerful predictor of outcome in acute lymphoblastic leukemia (ALL). Achievement of a negative MRD state assessed by multicolor flowcytometry (MFC) is an important predictor of disease-free survival (DFS) and overall survival (OS) in ALL patients. We sought to determine whether panels of antibodies combination are more suitable for detection of MRD in Childhood ALL. Eighty-four (84) patients with ALL (B-lineage subtype) were enrolled in this study. Normal template for B cell precursors was established in 15 control participants using 4-four panels of monoclonal Antibodies (Mo Abs),{CD22, CD45, CD58 and CD97 in combination with CD10, CD19, CD34}. At diagnosis, CD22 exhibited the lowest incidence of expression in only 50% of all patients, while CD45, CD58, and CD97 were expressed in 80.9, 59.5 and 92.8%, respectively. Analysis of MRD was performed for each Mo Abs combination at day 0 and day 14 post-induction of chemotherapy by 4-color (FCM). The incidence of MRD was 61.9, 70.6, 60.0 and 55.1% for CD22, CD45, CD58 and CD97, respectively. In B-ALL patients, (CD10/CD19/CD34/CD45) + (CD10/CD19/CD34/CD97) represented the highest incidence of expression of leukemic cells markers with a significant correlation with blasts count, suggesting that these are more specific for MRD detection. Also FCM is relatively cost effective for detection of MRD in ALL patients and its applicability in routine leukemia lab is valuable. MRD evaluation at the end of the induction therapy (i.e. day 35 or 42 according to the different schedules) is advised. Also, Ig/T cell receptor gene rearrangements and gene fusions analyzed by polymerase chain reaction (PCR) are preferred.

Cardioprotective effect of renalase in 5/6 nephrectomized rats

Cardiovascular disease (CVD) remains one of the most common causes of morbidity and mortality in patients with chronic renal disease. It has been recently postulated that the loss or reduced levels of renalase in patients with chronic renal disease are, at least in part, responsible for elevated plasma catecholamine levels, which leads to increased CVD. Therefore, the aim of the present study was to evaluate whether renalase administration might serve as a therapeutic drug, decreasing the severity of CVD in 5/6 nephrectomized (Nx) rats. The current study was conducted on 30 male Wistar albino rats divided into the following groups: group I: sham-operated rats that received phosphate-buffered saline (PBS) subcutaneously (s.c.) for 4 weeks following sham operation, group II: rats in which 5/6 Nx was done and then the rats received PBS daily s.c. for 4 weeks following 5/6 Nx, and group III: rats in which 5/6 Nx was done and then the rats received recombinant renalase daily s.c. for 4 weeks following 5/6 Nx. 5/6 nephrectomy resulted in a significant increase in mean arterial pressure, left ventricular (LV)/body weight ratio, LV hydroxyproline concentration, plasma creatinine, blood urea nitrogen (BUN), and noradrenaline (NA) levels as well as significant decrease in LV papillary muscle developed tension in group II compared with the sham-operated group I. Administration of renalase to group III resulted in significant amelioration of all studied parameters with the exception of plasma creatinine and BUN which were not significantly different from nontreated group II. The results of the current study identify renalase as a new therapeutic modality that might modulate cardiac function and systemic blood pressure in renalase-deficient states like chronic renal disease.

Clinical significance of T-regulatory cells in B-cell non-Hodgkin's lymphoma

Regulatory T cells (Tregs) play a central role in protecting the host from autoimmune diseases. However, Tregs also pose a major problem to anti-tumor immunity. The expansion and accumulation of these immunosuppressive cells correlate with advanced tumor growth and predict poor disease prognosis. The study aims at evaluation of the clinical role of regulatory T cells in B-cell Non-Hodgkin's lymphoma. The study was carried out on 45 de novo patients with B- NHL, they included 26 males and 19 females and 20 apparently healthy age-matched as control. Diagnosis of lymphoma was done by lymph node biopsy, 15 patients had diffuse large B cell lymphoma (DLBCL), 9 follicular lymphoma (FL), 8 small cell lymphocytic lymphoma (SCLL), 7 marginal zone lymphoma (MZL) and 6 had mantle cell lymphoma (MCL). Tregs (CD4+CD25+ FoxP+3) were analyzed by Flowcytometry. The mean percent was 10.9 +/- 1.6% in diffuse large B cell lymphoma, 12.4 +/- 1.4% in follicular lymphoma, 13.7 +/- 2.4% in small cell lymphocytic lymphoma, 11.9 +/- 1.9% in marginal zone lymphoma and 13.5 +/- 1.35% in mantle cell lymphoma as compared to 5.9 +/- 0.96% in controls with a significant increase in the patients in relation to control group. Tregs was significantly increased in advanced stages of the disease, in bone marrow infiltration and in patients with increased LDH level. In conclusion, Tregs may play a role in modifying immune responses in patients with lymphomas and may be useful in immunotherapy and new anti-lymphoma strategies involving depletion of Tregs.

Does postdural puncture headache left untreated lead to subdural hematoma? Case report and review of the literature

The patient was a 39-year-old pregnant woman who was scheduled for cesarean section. Spinal anesthesia was induced using a 26-gauge needle with an atraumatic bevel. Postoperatively, the patient developed cranial subdural hematoma manifesting as severe non-postural headache, associated with right eye tearing, fifth cranial nerve palsy and left hemiparesis. The diagnosis was confirmed by computed tomography scan. The patient was managed by careful neurological follow-up associated with conservative treatment and recovered fully after 12 weeks. Our report reviews the literature on 46 patients who developed a postdural puncture headache complicated by subdural hematoma following spinal or epidural anesthesia. It is possible that postdural puncture headache left untreated may be complicated by the development of subdural hematoma. Patients developing a postdural puncture headache unrelieved by conservative measures, as well as the change from postural to non-postural, require careful follow-up for early diagnosis and management of possible subdural hematoma.

Progressive hypoxemia, hypercarbia and hyperthermia associated with prolonged anesthesia--a case report

The authors report a case of 66-year-old female patient, 55 kg, ASA I who, under general anesthesia in supine position, developed gradual hypoxemia (from a baseline PaO2 of 250 to 91 mmHg), carbon dioxide build up (from a baseline PaCO2 31 to 41 mmHg) associated with gradual hyperthermia up to 38.3 degrees C over seven hours, intraoperatively. These observations were noted while using a semi-closed carbon dioxide absorption circuit in conjunction with the Hygroster filter at a fresh gas flow of 4 1/min of 50% nitrous oxide in oxygen. While the ventilation pattern was unchanged throughout the procedure, there was a change in exhaled tidal and minute ventilation volume with a net decrease of 28 ml and 0.4 l/min respectively. Findings are probably the result of pulmonary atelecatasis under general anesthesia due to the use of a relatively high-inspired oxygen concentration (50%). In addition, the use of a high humidity and temperature heat moisture exchanger (HME) filter (Hygroster) in conjunction with the circle absorber system may have resulted in over humidification and aggravated the pulmonary atelecatasis over the long operative time.

Melamine-formaldehyde-NTA chelating gel resin: Synthesis, characterization and application for copper(II) ion removal from synthetic wastewater

A new chelating resin was synthesised by anchoring nitrilotriacetic acid (NTA) to melamine during the melamine-formaldehyde gelling reaction in the presence of water, using acetone and guaiacol as a porogen mixture. This technique gives a porous chelating gel resin capable of removing heavy metals from wastewater. FT-IR, XRD, elemental analysis, surface area and water regain measurements were conducted for characterization of the new chelating gel resin. A comprehensive adsorption study (kinetics isotherm, and thermodynamics) of Cu(II) removal from synthetic acidic aqueous solutions by adsorption on this resin was conducted regarding the effects of time, temperature, initial pH and copper(II) initial concentration.

Effect of alpha-stat vs. pH-stat strategies on cerebral oximetry during moderate hypothermic cardiopulmonary bypass

BACKGROUND AND OBJECTIVES

This study was undertaken to compare the effect of alpha-stat vs. pH-stat strategies for acid-base management on regional cerebral oxygen saturation (RsO2) in patients undergoing moderate hypothermic haemodilution cardiopulmonary bypass (CPB).

METHODS

In 14 adult patients undergoing elective coronary artery bypass grafting, an awake RsO2 baseline value was monitored using a cerebral oximeter (INVOS 5100). Cerebral oximetry was then monitored continuously following anaesthesia and during the whole period of CPB. Mean +/- SD of RsO2, CO2, mean arterial pressure and haematocrit were determined before bypass and during the moderate hypothermic phase of the CPB using the alpha-stat followed by pH-stat strategies of acid-base management. Alpha-stat was then maintained throughout the whole period of CPB.

RESULTS

The mean baseline RsO2 in the awake patient breathing room air was 59.6 +/- 5.3%. Following anaesthesia and ventilation with 100% oxygen, RsO2 increased up to 75.9 +/- 6.7%. Going on bypass, RsO2 significantly decreased from a pre-bypass value of 75.9 +/- 6.7% to 62.9 +/- 6.3% during the initial phase of alpha-stat strategy. Shifting to pH-stat strategy resulted in a significant increase of RsO2 from 62.9 +/- 6.3% to 72.1 +/- 6.6%. Resuming the alpha-stat strategy resulted in a significant decrease of RsO2 to 62.9 +/- 7.8% which was similar to the RsO2 value during the initial phase of alpha-stat.

CONCLUSION

During moderate hypothermic haemodilutional CPB, the RsO2 was significantly higher during the pH-stat than during the alpha-stat strategy. However, the RsO2 during pH-stat management was significantly higher than the baseline RsO2 value in the awake patient breathing room air, denoting luxury cerebral perfusion. In contrast, the RsO2 during alpha-stat was only slightly higher than the baseline RsO2, suggesting that the alpha-stat strategy avoids luxury perfusion, but can maintain adequate cerebral oxygen supply-demand balance during moderate hypothermic haemodilutional CPB.

Does postdural puncture headache left untreated lead to subdural hematoma? Case report and review of the literature

The patient was a 39-year-old pregnant woman who was scheduled for cesarean section. Spinal anesthesia was induced using a 26-gauge needle with an atraumatic bevel. Postoperatively, the patient developed cranial subdural hematoma manifesting as severe non-postural headache, associated with right eye tearing, fifth cranial nerve palsy and left hemiparesis. The diagnosis was confirmed by computed tomography scan. The patient was managed by careful neurological follow-up associated with conservative treatment and recovered fully after 12 weeks. Our report reviews the literature on 46 patients who developed a postdural puncture headache complicated by subdural hematoma following spinal or epidural anesthesia. It is possible that postdural puncture headache left untreated may be complicated by the development of subdural hematoma. Patients developing a postdural puncture headache unrelieved by conservative measures, as well as the change from postural to non-postural, require careful follow-up for early diagnosis and management of possible subdural hematoma.

Does isoflurane optimize myocardial protection during cardiopulmonary bypass?

OBJECTIVE

To investigate the possible myocardial protective effect of isoflurane during aortic cross-clamp and cardioplegic cardiac arrest in patients undergoing conventional coronary artery bypass graft surgery.

DESIGN

Prospective, randomized.

SETTING

University medical center.

PARTICIPANTS

Forty-nine patients undergoing elective coronary artery bypass graft surgery divided into 2 groups: control group (n = 21) and isoflurane group (n = 28).

INTERVENTION

Isoflurane was administered in the pre-cardiopulmonary bypass (CPB) period to the isoflurane group.

MEASUREMENTS AND MAIN RESULTS

Hemodynamics and ST- segment variations were monitored in the pre-CPB period and after weaning from CPB in both groups. Incidence of reperfusion arrhythmias after release of aortic cross-clamp was compared. In the isoflurane group, the mean cardiac index after CPB was significantly higher than the pre-CPB value, whereas no difference between the 2 values was found in the control group. The higher cardiac index in the isoflurane group was associated with a lesser degree of ST- segment changes than in the control group. There was no significant difference between the 2 groups in the incidence of reperfusion arrhythmias after release of aortic cross-clamp.

CONCLUSION

The present report suggests that administration of isoflurane before aortic cross-clamping in patients undergoing coronary artery bypass graft surgery may optimize the myocardial protective effect of cardioplegia. Isoflurane may be particularly advantageous whenever prolonged periods of aortic cross-clamping or inadequate delivery of cardioplegia is expected.

Anesthesia and critical care of thymectomy for myasthenia gravis

Myasthenia gravis is an autoimmune disease resulting from the production of antibodies against the ACh receptors of the neuromuscular synapse. The thymus gland is involved in the autosensitization process, and the disease frequently is associated with thymic morphologic abnormalities. There is a consensus that all adults with generalized MG should have a thymectomy. This recommendation has been propagated by the safety of the procedure and excellent outcome. Removal of as much thymic tissue as possible (anterior mediastinal exenteration) by transsternal approach is the logical goal of thymectomy in the treatment of MG. Transcervical approach and VATS, however, are less invasive and have been used in patients who have MG unaccompanied by thymoma. Optimization of the condition of the myasthenic patients can markedly decrease the risk of surgery and improve the outcome. Two techniques have been recommended for general anesthesia in the myasthenic patient. Because of the unpredictable response to succinylcholine and the marked sensitivity to nondepolarizing muscle relaxants, some anesthesiologists avoid muscle relaxants and depend on deep inhalational anesthesia, such as halothane, isoflurane, or sevoflurane, for tracheal intubation and maintenance of anesthesia. Others, however, use a balanced technique of anesthesia that includes the use of carefully titrated muscle relaxants. The most important preoperative factor predicting the need for postoperative mechanical ventilation is the severity of bulbar involvement (Ossermann group 3 and 4), usually indicated by significant dysphagia and dysarthria associated with borderline respiratory dysfunction. Thymectomy benefits nearly 96% of patients: 46% develop complete remission, 50% are asymptomatic or improve on therapy, and 4% remain the same. The time from diagnosis to surgery is shorter than 8 months, and mild or moderate myasthenic symptoms are the main prognostic factors that predict the best outcome after thymectomy.

Single vital capacity breath for preoxygenation

PURPOSE

The report investigates, in awake patients before induction of anesthesia, the effect of preoxygenation by the single vital capacity breath technique following forced exhalation on the mean arterial PO2 (PaO2).

METHODS

In 10 adult patients undergoing elective surgery, the mean PaO2 values achieved 30 sec after preoxygenation by the single vital capacity breath technique was compared with the mean PaO2 values achieved by preoxygenation by the traditional tidal volume breathing for three minutes. Each patient served as her/his own control.

RESULTS

The mean PaO2 following the single vital capacity breath technique was higher (295 +/- 67 mmHg) than that achieved by the traditional tidal volume breathing technique at 30 sec and 60 sec, and was not significantly different from that achieved by the traditional technique after three minutes (307 +/- 70 mmHg).

CONCLUSION

The single vital capacity breath technique following forced exhalation can rapidly provide adequate preoxygenation within 30 sec.

A new cut-off point of thyromental distance for prediction of difficult airway

BACKGROUND

Difficult intubation, often unexpected, remains a primary concern for the anesthesiologist. None of the bedside tests have proven to be efficacious and highly predictive. The prupose of this study was to correlate the full range of thyromental distance with both the Cormack grade and the Mallampati score.

METHODS

One hundred and sixty patients undergoing general anesthesia were included in the study. Patients with abnormal atlanto-occipital extension, small chin size and mouth opening were excluded from the study. The thyromental distance, the Mallampati score, and the Cormack grade were determined in all patients. The correlation between the thyromental distance and each of the Cormack grade and the Mallampati score was determined, as well as the correlation between the Mallampati score and the Cormack grade. The cut-off value of the tyromental distance that discriminated best between patients with easy glottic visualization (Cormack grade 1,2) vs. difficult visualization (Cormack grade 3,4) was derived.

RESULTS

A significant and high correlation was observed between the thyromental distance and the Cormack grade (r = -0.72). In contrast, a lower correlation was observed between the thyromental distance and the Mallampati score (r = -0.41) and the Mallampati score and the Cormack grade (r = 0.47). A cut-off value for the TMD of 4 cm was the best in discriminating between patients with difficult and easy glottic visualization. The combination of TMD < or = 4 cm and Mallampati score of 3,4 predicted the patients with the most difficult glottic visualization.

CONCLUSION

Patients with a thyromental distance greater than 4 cm can be easily intubated. In contrast, when the TMD < or = 4 cm, tracheal intubation is difficult in 48% of patients if the Mallampati score is 1,2 and in 79% if the Mallampati score is 3 or 4.

Sevoflurane anesthesia in a myasthenic patient undergoing transsternal thymectomy

Myasthenia gravis (MG) is an autoimmune disease resulting from the production of antibodies against the acetylcholine receptors of the neuromuscular synapse. The thymus gland is involved in the autosensitization process, and there is a consensus that all adults with generalized MG should have a thymectomy. Removal of a much thymic tissue as possible via the transsternal approach in the logic goal of thymectomy in the treatment of MG. Because of the unpredictable response to succinylcholine and the marked sensitivity to nondepolarizing muscle relaxants in the MG patients, some anesthesiologists avoid the use of muscle relaxants in the myasthenic patients, and depend on deep inhalation anesthesia, such as halothane, isoflurane or sevoflurane. In the present report, we used sevoflurane 4%, without supplementation by muscle relaxants, for the induction and maintenance of anesthesia in a MG patient undergoing transsternal thymectomy. The report reviews the anesthetic technique, and describes the electromyographic (EMG) changes following sevoflurane.