Solvent triggered irreversible shape morphism of biopolymer films.

We report the controlled reversible and irreversible folding behavior of a biopolymer film simply by tuning the solvent characteristics. Generally, solvent triggered folding of soft membranes or film is achieved by unfolding. Here, we show that this unfolding behavior can be suppressed/delayed or even completely eliminated by altering the intrinsic nature of the solvent. A reversible folding of biopolymer film is observed in response to water, whereas, an irreversible folding is observed in the presence of an aromatic alcohol (AA) solution of different molar concentrations. The folding and unfolding behavior originates from the coupled deformation-diffusion phenomena. Our study indicates that the presence of an AA influences the relaxation behavior of polymer chains, which in turn affects the release of stored strain energy during folding. Controlling the reversibility as well as the actuation time of the biopolymer film by tuning the solvent is explained in detail at the bulk scale by applying appropriate experimental techniques. The underlying mechanism for the observed phenomena is complemented by performing a simulation study for a single polymer chain at the molecular length scale. Due to the solvent-triggered hygromorphic response, biopolymer films exhibit huge potential as sensors, soft robots, drug delivery agents, morphing medical devices and in biomedical applications. We provide experimental evidence for the weight lifting capacity of permanently folded membranes, amounting to ∼200 times their own weight.

Folding behavior and molecular mechanism of cross-linked biopolymer film in response to water.

Water responsive biopolymers are gaining enormous attention in the different areas of research and applications related to self-folding. In this work, we report that cross-linking is an efficient means of modifying a single layer biopolymer film for a controlled and predictable pathway of folding. The initiation of the folding of a film is caused by the diffusion of water molecules along the film thickness. However, this folding is observed to take place in an unpredictable and random fashion with a pristine biopolymer film and a nano-particle reinforced film. The mechanical properties and the diffusion characteristics of the film are strongly interrelated and affect the overall folding behavior. The underlying mechanism behind this relation is appropriately substantiated by an in depth molecular dynamic study. The detailed characterization of the folding shape and material behavior is performed applying suitable experimental techniques. The potential application of the controlled folding of the cross-linked film as a sensor and as a soft crane is demonstrated in this report.

Perioperative Dyselectrolytemia in Patients Undergoing Transurethral Resection of the Prostate Using 0.9% Normal Saline Irrigation.

BACKGROUND: The choice of irrigation fluid used in transurethral resection of the prostate (TURP) has a significant impact on serum electrolyte levels. Among the many available options, 0.9% normal saline (NS) is considered to be more physiological. MATERIAL AND METHODS: This observational study was conducted on 60 adult males aged 50-70 years, classified as American Society of Anesthesiologists grade 1 and 2, undergoing TURP with 0.9% NS irrigation under spinal anesthesia achieved with a mixture of 0.5% heavy bupivacaine. The patients' hematocrit and serum electrolyte levels were obtained after six hours and compared with preoperative values. RESULTS: Hematocrit reduced from 40.32 ± 6.27 to 31.07 ± 5.40 (p < 0.001). Both serum sodium and potassium decreased from 136.77 ± 3.27 to 128.31 ± 5.91 and from 4.02 ± 0.26 to 3.81 ± 0.36, respectively (p < 0.001). However, serum chloride showed only a minimal increase from 101.58 ± 2.88 to 102.25 ± 1.66 (p < 0.12). CONCLUSION: Although the changes in serum sodium and potassium were statistically significant, they did not have any physiological consequences in our study. However, this emphasizes the importance of vigilant electrolyte monitoring to identify and mitigate the risk of electrolyte disturbances during TURP surgeries.

Duloxetine in Reducing Catheter-Related Bladder Discomfort: A Prospective, Randomized, Double-Blind, Placebo-Controlled Study.

OBJECTIVE: The excessive desire to void with discomfort in the supra-pubic region, which is experienced postoperatively by patients who underwent urinary catheterization, is known as catheter-related bladder discomfort. In this study, we evaluated duloxetine, a selective serotonin and norepinephrine reuptake inhibitor, in preventing catheter-related bladder discomfort. MATERIAL AND METHODS: Around 64 adults (18-60 years), of either sex, with American Society of American Society of Anesthesiologists (ASA) physical status I and II, scheduled to undergo elective gastrointestinal carcinoma surgeries under general anesthesia were analyzed in the final assessment of 2 comparative groups C and D of 32 patients each. Group D received 1 ranitidine tablet of 150 mg and 1 duloxetine tablet of 60 mg, while group C patients received 2 tablets of ranitidine of 75 mg 2 hours prior to induction. A 16 F Foley catheter was used to catheterize bladder intra-operatively, and 10 mL of distilled water was used to fill the balloon. At 0, 1, 2, and 6 hours, the catheter-related bladder discomfort was evaluated, and categorized into none, mild, moderate, and severe. The study drug's adverse effects, if any, were reported. RESULTS: At all-time intervals, group D had lower incidence and severity of catheterrelated bladder discomfort than group C (P < .05). Compared to group C, patients in group D had a higher incidence of nausea, dizziness, and vomiting; nevertheless, the difference was statistically insignificant (P > .05). CONCLUSION: Duloxetine of 60 mg given orally 2 hours before induction decreases the incidence and severity of catheter-related bladder discomfort.

A Comparative Study of Isobaric 1% Chloroprocaine With 0.5% Isobaric Bupivacaine for Ureteroscopic Lithotripsy Under Spinal Anaesthesia: A Prospective Randomised Study.

Introduction Day-care surgery has become an immensely popular modality of treatment throughout the globe. Ureteroscopic lithotripsy (URSL) surgery is commonly performed on a day-care basis, and the duration of surgery ranges from 15 minutes to 45 minutes. URSL is routinely done under spinal anaesthesia. Spinal anaesthesia with conventional drugs has its problems like delayed regression and urinary retention, necessitating a longer hospital stay, thereby increasing the time and resources needed. For day-care surgery, short-acting local anaesthetics have a quicker onset with fewer side effects, and drugs that ensure quicker hospital discharge are more often preferred over long-acting anaesthetics. For spinal anaesthesia, we planned to perform a randomised prospective study to compare the effectiveness of 40 mg of preservative-free 1% chloroprocaine over 10 mg of plain 0.5% isobaric bupivacaine. Materials and method After obtaining clearance from the institute's ethical committee and written informed consent from the patients, 64 patients between the ages of 18 and 50 years of either sex belonging to American Society of Anesthesiologists (ASA) 1 and 2 scheduled for URSL surgery were included in our study. They were randomised using a computer-generated sealed envelope technique into two groups. Group C received 4 ml of 1% isobaric chloroprocaine, and group B received 2 ml of 0.5% isobaric bupivacaine in the intrathecal space. The primary outcome was to compare the in-hospital time among both groups. Our secondary outcomes were the onset time of motor and sensory blocks, the duration of the blocks, time to unaided ambulation and voiding, the need for an overnight stay, and the side effects like postoperative nausea and vomiting (PONV), and urinary retention. The data were analysed using the unpaired t-test and chi-square test and calculated by SPSS 20.0 software version (IBM Corp., Armonk, NY). Results Final analyses were done among 60 patients. In-hospital time was significantly lower in group C as compared to group B (p<0.05). The onset time of sensory and motor blockade was significantly lower in group C as compared to group B (p<0.005). The duration of sensory and motor blockade was significantly less in group C as compared to group B (p<0.005). The time for unaided voiding and ambulation was less in group C as compared to group B. The need for an overnight stay was only needed in group B. The incidence of PONV and urinary retention was higher in group B. Conclusion In URSL surgery, the use of intrathecal 1% isobaric chloroprocaine 40 mg resulted in a reduced hospital stay time as compared to the use of intrathecal 10 mg of 0.5% isobaric bupivacaine. Also, it resulted in a significantly faster onset and faster regression of the block, less duration of the blockade, shorter time to ambulation and micturition, and a requirement for an overnight stay when compared with isobaric spinal bupivacaine.

Efficacy of Estradiol Cream for Venipuncture Pain in Obese Female Patients: A Pilot Study.

INTRODUCTION: Venipuncture is often a painful procedure causing significant anxiety, distress, and psychological consequences. We evaluated the efficacy of estradiol cream and compared it with a eutectic mixture of local anesthetics (EMLA) cream for alleviation of venipuncture pain and to make cannulation easy in female obese patients. MATERIALS AND METHODS: The clearance from the Institutional Ethical Committee as well as prior written and informed consent were obtained from the participants. A total of 105 obese female adult patients aged between 25 and 64 years belonging to the American Society of Anesthesiologists (ASA) physical status I and II with body mass index (BMI) > 30 kg/m2 were included in our study. The study participants were randomly allocated into three groups: In group I, a placebo cream was applied; in group II, estradiol cream was applied, and in group III, EMLA cream was applied. Any abnormal sensation at the site of application of the cream was noted and followed up at 0, 2, and 6 hours for the same. The primary outcome was the measurement of the severity of the pain experienced during venipuncture using the visual analog scale (VAS). Ease of cannulation was our secondary outcome. VAS was compared with the Z test. Statistical Package for the Social Sciences (SPSS) v16.0 software (SPSS Inc., Chicago) was used for statistical analysis. A p-value of <0.05 was considered statistically significant. RESULT: The final analysis was carried out on 25 patients in group I, 27 patients in group II, and 33 patients in group III. There was no significant improvement in the ease of cannulation in group II when compared to group I. The mean VAS was similar in group I and group II, whereas it was significantly reduced in group III (p < 0.05). CONCLUSION: EMLA cream was found to significantly reduce the pain of venipuncture in comparison to placebo and estradiol cream. There is no beneficial effect of estradiol cream in reducing the pain from venipuncture or in ease of cannulation compared to placebo.

Mysterious alarming mucormycosis: Anesthetic challenges in a series of four cases.

The sudden epidemic of mucormycosis amid COVID-19 pandemic has significantly challenged our understanding of the disease while affecting the whole medical and surgical management. Overzealous use of steroids in the management of covid-19 and uncontrolled diabetes mellitus has resulted in a tremendous rise in mucormycosis cases further burdening the already strained health care infrastructure and health care workers, especially the anesthesiologists. While working in a tertiary care institute of the country, we have been facing multiple challenges in its anesthetic management on a daily basis. This article is a case series involving four different patients who were operated for rhino-orbito-cerebral mucormycosis with a brief discussion on various aspects of this multisystem epidemic.

Insights on Water Dynamics in the Hygromorphic Phenomenon of Biopolymer Films.

Water-responsive biopolymer thin films with engineered matrix characteristics can accomplish desirable shape changing properties such as self-folding. Self-folding response of chitosan film is experimentally characterized by its total folding time and rate of folding. Here, atomistic simulation is employed to investigate the molecular mechanism responsible for modified self-folding behavior observed in nanoparticle reinforced chitosan films. The nanocomposite system is solvated with water content varying from 10% to 100% of total mass of the system. The free volume available for diffusion of water molecules is affected by the flexibility of glycosidic linkages present in chitosan chains. The increase in mobility of water molecules with increase in water content decides the rate of folding. A separate molecular system is modeled with confined region between nanoparticles densified with chitosan chains and water molecules. The thickness of confined region is determined from the critical distance of influence of nanoparticles on water molecules. The adsorption of water on nanoparticle surface and relaxation of chitosan chains are responsible for increased total folding time with nanoparticle concentration. This simulation study, complemented with experimental observations provides a useful insight into the designing of actuators and sensors based on the phenomenon of hygromorphism.

A Case of Subclavian Artery Aneurysm with History of Ischemic Heart Disease Operated Under Cervical Epidural Anesthesia.

Subclavian artery aneurysm is usually operated under general anesthesia (GA), but in specific situations, it can also be conducted under regional anesthesia (RA) such as cervical epidural anesthesia (CEA). A 48-year-old male presented with chief complaint of progressive swelling in the right side of the neck for the past 3 months following trauma. He was diagnosed as subclavian artery aneurysm, and surgical intervention was advised. He had previous history of angina 4 months back for which tablet aspirin 75 mg and tablet clopidogrel 75 mg once daily was prescribed. Cardiological evaluation revealed of an ejection fraction of around 30% with mild left ventricular hypokinesia and grade 2 diastolic dysfunction. Due to the poor cardiac functional status of the patient, RA with CEA was planned. The risk with GA in cases with a history of myocardial ischemia is more than RA, hence, it is better to use CEA which is equally efficacious in such high-risk cases.

Molecular mechanisms in deformation of cross-linked hydrogel nanocomposite.

The self-folding behavior in response to external stimuli observed in hydrogels is potentially used in biomedical applications. However, the use of hydrogels is limited because of its reduced mechanical properties. These properties are enhanced when the hydrogels are cross-linked and reinforced with nanoparticles. In this work, molecular dynamics (MD) simulation is applied to perform uniaxial tension and pull out tests to understand the mechanism contributing towards the enhanced mechanical properties. Also, nanomechanical characterization is performed using quasi static nanoindentation experiments to determine the Young's modulus of hydrogels in the presence of nanoparticles. The stress-strain responses for chitosan (CS), chitosan reinforced with hydroxyapatite (HAP) and cross-linked chitosan are obtained from uniaxial tension test. It is observed that the Young's modulus and maximum stress increase as the HAP content increases and also with cross-linking process. Load displacement plot from pullout test is compared for uncross-linked and cross-linked chitosan chains on hydroxyapatite surface. MD simulation reveals that the variation in the dihedral conformation of chitosan chains and the evolution of internal structural variables are associated with mechanical properties. Additional results reveal that the formation of hydrogen bonds and electrostatic interactions is responsible for the above variations in different systems.

Nanomechanical characterization and molecular mechanism study of nanoparticle reinforced and cross-linked chitosan biopolymer.

Chitosan (CS) is a biomaterial that offers many sophisticated and innovative applications in the biomedical field owing to its excellent characteristics of biodegradability, biocompatibility and non-toxicity. However, very low mechanical properties of chitosan polymer impose restriction on its further development. Cross-linking and nanoparticle reinforcement are the two possible methods to improve the mechanical properties of chitosan films. In this research, these two methods are adopted individually by using tripolyphosphate as cross-linker and nano-hydroxyapatite as particle reinforcement. The nanomechanical characterizations under static loading conditions are performed on these modified chitosan films. It is observed that nanoparticle reinforcement provided necessary mechanical properties such as ductility and modulus. The mechanisms involved in improvement of mechanical properties due to particle reinforcement are studied by molecular dynamics (MD). Further, improvement in mechanical properties due to combination of particle reinforcement and cross-linking agent with chitosan is investigated. The stress relaxation behavior for all these types of films is characterized under dynamic loading conditions using dynamic mechanical analysis (nanoDMA) experiment. A viscoelastic solid like response is observed for all types of film with modulus relaxing by 3-6% of its initial value. A suitable generalized Maxwell model is fitted with the obtained viscoelastic response of these films. The response to nano-scratch behavior is also studied for particle reinforced composite films.