COMPARISON OF DEXMEDETOMIDINE AND FENTANYL ON AIRWAY RESPONSE AND HEMODYNAMICS DURING TRACHEAL EXTUBATION

Background: Extubation is associated with various circulatory and airway responses. Various pharmacological measures including fentanyl and dexmedetomidine have been used to blunt the reflex without compromising the spontaneous respiration. In this study we wanted to compare dexmedetomidine and fentanyl on airway response, smoothness of extubation and hemodynamic changes. Methodology: A total of 68 patients undergoing surgery under general anesthesia with endotracheal intubation, were randomized into two groups. Group A received dexmedetomidine 0.5 mcg/kg and Group B received 1 mcg/kg of fentanyl with the start of skin suturing over a period of 10 minutes via syringe pump. Airway reflex during suction and smoothness of extubation were assessed. Level of sedation during suction, extubation and then every 5 minutes post extubation for 15 minutes were recorded. Hemodynamic parameters were assessed every 5 minutes with start of test solution till extubation and then every 5 minutes for 15 minutes. Results: A total of 68 patients were evaluated in the study. In dexmedetomidine group, 67.6% of patients had no cough on extubation while in fentanyl group 35.3% of patients had no cough on extubation which was statistically significant (p value 0.015). Mean heart rate during extubation increased in both the groups but the increase was 39% in Group B and 11% in Group A from baseline which was statistically significant (p value < 0.001). There was rise in mean systolic and mean arterial pressure during extubation in both the groups but the increase was significantly higher in fentanyl group. Patients in dexmedetomidine group were more sedated but there were no any adverse events. Conclusion: With the results obtained from the study, it is concluded that dexmedetomidine 0.5 mcg/kg over 10 minutes before extubation is effective in alleviating airway response and haemodynamics compared to fentanyl 1 mcg/kg.

Cardiovagal Baroreflex Hysteresis Using Ellipses in Response to Postural Changes

The cardiovagal branch of the baroreflex is of high clinical relevance when detecting disturbances of the autonomic nervous system. The hysteresis of the baroreflex is assessed using provoked and spontaneous changes in blood pressure. We propose a novel ellipse analysis to characterize hysteresis of the spontaneous respiration-related cardiovagal baroreflex for orthostatic test. Up and down sequences of pressure changes as well as the working point of baroreflex are considered. The EuroBaVar data set for supine and standing was employed to extract heartbeat intervals and blood pressure values. The latter values formed polygons into which a bivariate normal distribution was fitted with its properties determining proposed ellipses of baroreflex. More than 80% of ellipses are formed out of nonoverlapping and delayed up and down sequences highlighting baroreflex hysteresis. In the supine position, the ellipses are more elongated (by about 46%) and steeper (by about 4.3° as median) than standing, indicating larger heart interval variability (70.7 versus 47.9 ms) and smaller blood pressure variability (5.8 versus 8.9 mmHg) in supine. The ellipses show a higher baroreflex sensitivity for supine (15.7 ms/mmHg as median) than standing (7 ms/mmHg). The center of the ellipse moves from supine to standing, which describes the overall sigmoid shape of the baroreflex with the moving working point. In contrast to regression analysis, the proposed method considers gain and set-point changes during respiration, offers instructive insights into the resulting hysteresis of the spontaneous cardiovagal baroreflex with respiration as stimuli, and provides a new tool for its future analysis.

Causes and Treatment of Hypoxia during Total Hip Arthroplasty in Elderly Patients: A Case Report

Intraoperative hypoxia occurs in approximately 6.8% of surgeries and requires appropriate management to avoid poor outcomes, such as increased mortality or extended hospitalization. Hypoxia can be caused by a variety of factors, including laryngospasm, inhalational anesthetics, and surgery for abdominal pathology or hip fractures. In particular, elderly patients are more vulnerable to hypoxia due to their existing lung diseases or respiratory muscle weakness. This study presents the cases of two elderly patients who developed hypoxia during total hip arthroplasty under general anesthesia. Positive end expiratory pressure, the recruitment maneuver, and increased fraction of inspired oxygen improved hypoxia only temporarily, and patients’ oxygen saturation level again dropped to 79–80%. We suspected that hypoxia was caused by atelectasis and, therefore, resumed spontaneous respiration. Thereafter, both the patients showed an improvement in hypoxia. Intraoperative hypoxia that is suspected to be caused by atelectasis can be improved by securing sufficient lung volume for respiration through increased muscle tone with spontaneous respiration.

Effects of different sedatives/analgesics on stress responses in patients undergoing craniotomy and bone flap decompression

Objective To explore the effects of sedation and analgesia with dexmedetomidine and other drugs on the stress response in patients with cerebral hemorrhage after craniotomy hematoma removal and bone flap decompression and insertion of an indwelling endotracheal catheter. Methods A total of 180 patients with cerebral hemorrhage with consciousness disturbance who underwent emergency surgery were included in this study. They were divided into six groups treated with propofol, dexmedetomidine, lidocaine, sufentanil, dezocine, and remifentanil, respectively. Intravenous medication was given after recovery of spontaneous respiration, and stress responses were compared among the group. Results Serum concentrations of norepinephrine, epinephrine, and cortisol and systolic blood pressure were significantly correlated with drug treatment. Serum norepinephrine concentrations differed significantly among the groups, except between the sufentanil and propofol groups. There were significant differences in serum epinephrine concentrations among all groups, and significant differences in serum cortisol concentrations among all groups, except the propofol, dexmedetomidine, and lidocaine groups. Conclusion Dexmedetomidine can reduce the stress response in patients with intracerebral hemorrhage undergoing emergency craniotomy and bone flap decompression, and can reduce adverse events from an indwelling endotracheal catheter 3 hours post-operation.

Digitization and Analysis of Capnography Using Image Processing Technique

The study of carbon dioxide expiration is called capnometry. The graphical representation of capnometry is called capnography. There is a growing interest in the usage of capnography as the usage has expanded toward the study of metabolism, circulation, lung perfusion and diffusion, quality of spontaneous respiration, and patency of airways outside of its typical usage in the anesthetic and emergency medicine field. The parameters of the capnograph could be classified as carbon dioxide (CO2) concentration and time points and coordinates, slopes angle, volumetric studies, and functional transformation of wave data. Up to date, there is no gold standard device for the calculation of the capnographic parameters. Capnography digitization using the image processing technique could serve as an option. From the algorithm we developed, eight identical breath waves were tested by four investigators. The values of the parameters chosen showed no significant difference between investigators. Although there were no significant differences between any of the parameters tested, there were a few related parameters that were not calculable. Further testing after refinement of the algorithm could be done. As more capnographic parameters are being derived and rediscovered by clinicians and researchers alike for both lung and non-lung-related diseases, there is a dire need for data analysis and interpretation. Although the proposed algorithm still needs minor refinements and further large-scale testing, we proposed that the digitization of the capnograph via image processing technique could serve as an intellectual option as it is fast, convenient, easy to use, and efficient.

Causes and Treatment of Hypoxia During Total Hip Arthroplasty in Elderly Patients: Case Report

There are several causes of hypoxia during and after surgery, and atelectasis is a common symptom that occurs during surgery. In particular, elderly patients are more vulnerable to hypoxia due to their existing lung diseases or respiratory muscle weakness. This study presents the cases of two elderly patients who developed hypoxia during total hip arthroplasty under general anesthesia. Positive end expiratory pressure, recruitment maneuver, and increased fraction of inspired oxygen improved hypoxia only temporarily, and patients&rsquo; oxygen saturation level again dropped to 79%&ndash;80%. We suspected that hypoxia was caused by atelectasis and, therefore, re-sumed spontaneous respiration. Thereafter, both the patients showed an improvement in hypoxia. Intraopera-tive hypoxia that is suspected to be caused by atelectasis can be improved by securing sufficient lung volume for respiration through increased muscle tone with spontaneous respiration

Volatile anesthetics maintain tidal volume and minute ventilation to a greater degree than propofol under spontaneous respiration

Background Although general anesthetics depress spontaneous respiration, the comprehensive effect of general anesthetics on respiratory function remains unclear. We aimed to investigate the effects of general anesthetics on spontaneous respiration in non-intubated mice with different types and doses of general anesthetic. Methods Adult C57BL/6 J mice were administered intravenous anesthetics, including propofol and etomidate, and inhalational anesthetics, including sevoflurane and isoflurane in vivo at doses of 0.5-, 1.0-, and 2.0-times the minimum alveolar concentration (MAC)/median effective dose (ED50) to induce loss of the righting reflex (LORR). Whole-body plethysmography (WBP) was applied to measure parameters of respiration under unrestricted conditions without endotracheal intubation. The alteration in respiratory sensitivity to carbon dioxide (CO2) under general anesthesia was also determined. The following respiratory parameters were continuously recorded during anesthesia or CO2 exposure: respiratory frequency (FR), tidal volume (TV), minute ventilation (MV), expiratory time (TE), inspiratory time (TI), and inspiratory–expiratory time ratio (I/E), and peak inspiratory flow. Results Sub-anesthetic concentrations (0.5 MAC) of sevoflurane or isoflurane increased FR, TV, and MV. With isoflurane and sevoflurane exposure, the CO2-evoked increases in FR, TV, and MV were decreased. Compared with inhalational anesthetics, propofol and etomidate induced respiratory suppression, affecting FR, TV, and MV. In 100% oxygen (O2), FR in the group that received propofol 1.0-times the ED50 was 69.63 ± 33.44 breaths/min compared with 155.68 ± 64.42 breaths/min in the etomidate-treated group. In the same groups, FR was 88.72 ± 34.51 breaths/min and 225.10 ± 59.82 breaths/min, respectively, in 3% CO2 and 144.17 ± 63.25 breaths/min and 197.70 ± 41.93 breaths/min, respectively, in 5% CO2. A higher CO2 sensitivity was found in etomidate-treated mice compared with propofol-treated mice. In addition, propofol induced a greater decrease in FR, MV, and I/E ratio compared with etomidate, sevoflurane, and isoflurane at equivalent doses (all P < 0.05). Conclusions General anesthetics differentially modulate spontaneous breathing in vivo. Volatile anesthetics increase FR, TV, and MV at sub-anesthetic concentrations, while they decrease FR at higher concentrations. Propofol consistently depressed respiratory parameters to a greater degree than etomidate.

Inhibition of Stress and Spontaneous Respiration: Efficacy and Safety of Monitored Anaesthesia Care by Remifentanil in Fibreoptic Bronchoscopy for Patients with Severe Tracheal Stenosis

Objective To determine the effective concentration of target-controlled infusion (TCI) of remifentanil used to inhibit stress during the treatment of severe tracheal stenosis with fibreoptic bronchoscopy and to evaluate the safety of the monitored anaesthesia care (MAC) by remifentanil.Methods A study of 60 patients with severe tracheal stenosis who underwent diagnostic and therapeutic fibreoptic bronchoscopy at Shanghai Pulmonary Hospital affiliated with Tongji University was performed. Dexmedetomidine was initially administered at a bolus dose (0.8 mcg/kg), followed by a 0.5 mcg/(kg·h) continuous infusion. Remifentanil was administered by TCI. When the target concentration was reached, the nasopharyngeal airway was inserted, and then oxygen was supplied by a connected anaesthesia machine. The effective concentration of remifentanil was titrated by the improved sequential method, and 30 patients were included. The EC95 of remifentanil was set as the plasma target concentration to evaluate the safety of the MAC, and another 30 patients were included. Remedy measures: Propofol (10-20 mg) was injected intravenously. The primary outcome measures were the cough score and the incidence and severity of hypoxemia. The tolerance score for nasopharyngeal airway placement, Ramsay sedation score, haemodynamic changes, satisfaction score, patients’ 24 h recall score, patients’ willingness to re-receive the procedure, and related adverse events were recorded.Results On the basis of sedation with dexmedetomidine, the EC95 of remifentanil for inhibiting the stress response in fibreoptic bronchoscopy performed on patients with severe tracheal stenosis was 2.710 ng/ml (95% CI, 2.471-4.473 ng/ml), and the EC50 was 2.243 ng/ml (95% CI, 2.061-2.446 ng/ml). Among the 30 patients who received an EC95 of remifentanil as the target concentration, 1 patient was remedied by injecting propofol; the tolerance score for insertion of the nasopharyngeal airway was 2, the score of Ramsay sedation was 3, and the cough score was 1. The incidence of respiratory depression was 50%, the incidence of hypoxemia was 20%, and 86.7% of patients with respiratory depression returned to normal by awakening. One patient returned to normal by mask-assisted ventilation, and another returned to normal by laryngeal mask mechanical ventilation. The satisfaction score of the operator was 9, the satisfaction score of the anaesthesiologist was 8, the satisfaction score of the patients was 10, the score of the patients' 24 h operative recall was 1, the rate of patient willingness to re-accept the procedure was 93.3%, the incidence of throat pain at 30 min after the end of the operation was 16.7%, and the circulation was stable during the operation. No pruritus, nausea, vomiting or other related adverse reactions were reported.Conclusion MAC using TCI of remifentanil can effectively inhibit the stress response to fibreoptic bronchoscopy in patients with severe tracheal stenosis while maintaining spontaneous breathing. The patients are safe and comfortable and express high satisfaction, making this method worthy of clinical application.Trial registration Registration date : 12/02/2021, Registration number: ChiCTR2100043380.