Changsheng Zhang

Objective: The ideal intra-operative inspired oxygen concentration remains controversial. We aimed to investigate the association between the intraoperative fraction of inspired oxygen (FiO₂) and the incidence of postoperative pulmonary complications (PPCs) in patients undergoing non-cardiothoracic surgery.Methods: This was a retrospective cohort study of elderly patients who underwent non-cardiothoracic surgery between April 2020 and January 2022. According to intraoperative FiO₂, patients were divided into low (≤60%) and high (>60%) FiO₂ groups. The primary outcome was the incidence of a composite of pulmonary complications (PPCs) within the first seven postoperative days. Propensity score matching (PSM) and inverse probability treatment weighting (IPTW) were conducted to adjust for baseline characteristic differences between the two groups. Multivariate logistic regression analysis was used to calculate the odds ratios (OR) for FiO₂ and PPCs.Results: Among the 3,515 included patients with a median age of 70 years (interquartile range: 68–74), 492 (14%) experienced PPCs within the first 7 postoperative days. Elevated FiO₂ was associated with an increased risk of PPCs in all the logistic regression models. The OR of the FiO₂ > 60% group was 1.252 (95%CI, 1.015–1.551, P = 0.038) in the univariate analysis. In the multivariate logistic regression models, the ORs of the FiO₂ > 60% group were 1.259 (Model 2), 1.314 (Model 3), and 1.32 (model 4). A balanced covariate distribution between the two groups was created using PSM or IPTW. The correlation between elevated FiO₂ and an increased risk of PPCs remained statistically significant with PSM analysis (OR, 1.393; 95% CI, 1.077–1.804; P = 0.012) and IPTW analysis (OR, 1.266; 95% CI, 1.086–1.476; P = 0.003).Conclusion: High intraoperative FiO₂ (>60%) was associated with the postoperative occurrence of pulmonary complications, independent of predefined risk factors, in elderly non-cardiothoracic surgery patients. High intraoperative FiO₂ should be applied cautiously in surgical patients vulnerable to PPCs.

BACKGROUND: A protective intra-operative lung ventilation strategy has been widely recommended for laparoscopic surgery. However, there is no consensus regarding the optimal level of positive end-expiratory pressure (PEEP) and its effects during pneumoperitoneum. Electrical impedance tomography (EIT) has recently been introduced as a bedside tool to monitor lung ventilation in real-time. OBJECTIVE: We hypothesised that individually titrated EIT-PEEP adjusted to the surgical intervention would improve respiratory mechanics during and after surgery. DESIGN: Randomised controlled trial. SETTING: First Medical Centre of Chinese PLA General Hospital, Beijing. PATIENTS: Seventy-five patients undergoing robotic-assisted laparoscopic hepatobiliary and pancreatic surgery under general anaesthesia. INTERVENTIONS: Patients were randomly assigned 2 : 1 to individualised EIT-titrated PEEP (PEEP_EIT; n = 50) or traditional PEEP 5 cmH₂O (PEEP_5 cmH2O; n = 25). The PEEP_EIT group received individually titrated EIT-PEEP during pneumoperitoneum. The PEEP_5 cmH2O group received PEEP of 5 cmH₂O during pneumoperitoneum. MAIN OUTCOME MEASURES: The primary outcome was respiratory system compliance during laparoscopic surgery. Secondary outcomes were individualised PEEP levels, oxygenation, respiratory and haemodynamic status, and occurrence of postoperative pulmonary complications (PPCs) within 7 days. RESULTS: Compared with PEEP_5 cmH2O, patients who received PEEP_EIT had higher respiratory system compliance (mean values during surgery of 44.3 ± 11.3 vs. 31.9 ± 6.6, ml cmH₂O⁻¹; P < 0.001), lower driving pressure (11.5 ± 2.1 vs. 14.0 ± 2.4 cmH₂O; P < 0.001), better oxygenation (mean P _aO₂/FiO₂ 427.5 ± 28.6 vs. 366.8 ± 36.4; P = 0.003), and less postoperative atelectasis (19.4 ± 1.6 vs. 46.3 ± 14.8 g of lung tissue mass; P = 0.003). Haemodynamic values did not differ significantly between the groups. No adverse effects were observed during surgery. CONCLUSION: Individualised PEEP by EIT may improve intra-operative pulmonary mechanics and oxygenation without impairing haemodynamic stability, and decrease postoperative atelectasis. TRIAL REGISTRATION: Chinese Clinical Trial Registry (www.chictr.org.cn) identifier: ChiCTR2100045166.

Background: The optimal ventilatory strategy for the face mask ventilation during anesthesia induction is still unknow.Methods: We evaluated the effect of two positive end-expiratory pressure (PEEP) levels (0 cmH₂O and 6 cmH₂O) and two oxygen concentration levels (1.0 and .6) on non-hypoxemic apnea time during face mask ventilation of anesthesia induction. Sixty adult patients scheduled for elective surgery were enrolled in this study. The patients were randomized to receive anesthesia induction with four different ventilation strategy under volume-controlled ventilation. Patients assigned to the LOZP group received low fraction of inspiration O₂ (FiO₂ = .6) and 0 PEEP. Patients assigned to the LOHP group received low fraction of inspiration O₂ (FiO₂ = .6) and 6 cmH₂O PEEP. Patients assigned to the HOZP group received high fraction of inspiration O₂ (FiO₂ = 1.0) and 0 PEEP. Patients assigned to the HOHP group received high fraction of inspiration O₂ (FiO₂ = 1.0) and 6cmH₂O PEEP. After 3 min of ventilation, the patient was intubated but disconnected from the breathing circuit. Ventilation was not initiated until the pulse oximetry dropped to 90%. The primary outcome was non-hypoxemic apnea time defined as the time from cessation of ventilation to a pulse oximeter reading of 90%. The secondary outcome was the PaO₂/FiO₂ ratio immediately after ventilation.Results: The non-hypoxemic apnea time was significantly longer in the group of HOHP when compared to the other three groups (192 s ± 70 s, 221 s ± 74 s, 284 s ± 101 s, and 353 s ± 85 s in the LOZP, LOHP, HOZP, and HOHP group, respectively). The PaO₂/FiO₂ ratio immediately after ventilation was significantly higher in the group of LOHP when compared to the other three groups (LOZP 393 ± 130, LOHP 496 ± 97, HOZP 335 ± 58, HOHP 391 ± 50). When compared the PaO₂/FiO₂ ratio immediately after ventilation to its value before administration of anesthesia, the PaO₂/FiO₂ ratio in the group of LOHP was improved, the group LOZP and HOHP remained the same, while the group HOZP significantly decreased.Conclusion: Application of PEEP and 100% of oxygen during face mask ventilation of induction could maximize the non-hypoxemic apnea time. However, the use of PEEP and 60% of oxygen during preoxygenation resulted in improved PaO₂/FiO₂ ratio.

Background: Clonidine is an anesthetic with favorable efficacy and safety profiles for caudal epidural block, but comparisons with other adjuvants need to be confirmed in pediatric patients.Aim: To investigate the effects of clonidine as an adjuvant in caudal epidural block to improve the intraoperative and postoperative analgesia in pediatric surgery.Methods: PubMed, Embase, and the Cochrane Library were searched for available papers published up to February 2021. The outcomes were pain score, duration of analgesia, complications, and number of analgesic requirements. The meta-analysis was performed using random-effects models.Results: Fifteen randomized controlled trials (RCTs) were included. There were no differences between clonidine and the control drug regarding the duration of analgesia (SMD = −0.71, 95%CI: −1.64, 0.23; I² = 95.5%, P_{heterogeneity} < 0.001), pain score (SMD = 0.35, 95%CI: −0.28, 0.98; I² = 80.8%, P_{heterogeneity} < 0.001), and requirement for additional analgesia (OR = 8.77, 95%CI: 0.70, 110.58, I² = 81.9%, P_{heterogeneity} = 0.004), but using clonidine resulted in fewer complications than the control drugs (OR = 0.33, 95%CI: 0.20, 0.54, I² = 21.8%, P_{heterogeneity} = 0.217). The sensitivity analysis showed that the results were robust. A publication bias was observed.Conclusion: Clonidine has the same efficacy as the other adjuvants for caudal epidural block for pediatric surgery but fewer complications. These results support clonidine as an adjuvant to local anesthetic, but additional studies should be conducted.

Background: Topical anesthesia is a crucial step in awake endotracheal intubation for providing favorable intubation conditions. The standard of care technique for awake intubation at our institution, which consists of oropharyngeal tetracaine spray, can result in inadequate mucosal anesthesia. Therefore, we sought to compare the effectiveness of dyclonine hydrochloride mucilage to the standard of care tetracaine in achieving anesthesia of the upper airways for awake endotracheal intubation. Methods: This is a randomized, assessor-blinded, prospective study. From Jun. 1st, 2019 to Aug. 1st, 2019, patients scheduled for either endoscopic submucosal dissection or peroral endoscopic myotomy were enrolled and randomly allocated into two groups after obtaining written informed consent: patients allocated to novel awake intubation care (Group N-AIC) received a single administration of oral dyclonine hydrochloride mucilage, whereas patients allocated to standard awake intubation care (Group S-AIC) received three oropharyngeal tetracaine sprays before transcricoid tetracaine injection before awake intubation. Mean arterial pressure (MAP), which was the primary outcome of this study, as well as heart rate (HR) were recorded throughout the procedure and compared between the two groups. Feeling of numbness, nausea, and intubation conditions after topical anesthesia were also assessed. Results: Sixty patients were enrolled and completed the study. Baseline MAP and HR were similar between the two groups. However, hemodynamic responses to intubation and gastrointestinal endoscopy, especially MAP, were significantly less elevated in Group N-AIC. The degree of numbness of the oropharyngeal mucosa after topical anesthesia did not differ between the two groups, neither did the feeling of nausea during laryngoscopy. The amount of pharyngeal secretions before intubation was less in Group N-AIC. Total intubation time was significantly shorter in Group N-AIC when compared to Group S-AIC (18.4 ± 2.86 vs. 22.3 ± 6.47, P < 0.05). Extubation bucking was significantly less frequent in Group N-AIC (13.3% vs. 76.7%). Patients received in Group N-AIC had a lower rate of post-extubation sore throat compared to Group S-AIC (6.7% vs. 43.3%). No adverse side effects attributable to either tetracaine or dyclonine were observed in this study. Conclusions: In awake endotracheal intubation, novel care using oral dyclonine hydrochloride mucilage can provide more favorable mucosal anesthesia and better intubation conditions compared to standard of care practice using oropharyngeal tetracaine spray. Trial registration: ChiCTR1900023151. Date of registration: May 14th, 2019.

Background:Topical anesthesia is a crucial step in awake endotracheal intubation for providing favorable intubation conditions. The standard of care technique for awake intubation at our institution, which consists of oropharyngeal tetracaine spray, can result in inadequate mucosal anesthesia. Therefore, we sought to compare the effectiveness of dyclonine hydrochloride mucilage to the standard of care tetracaine in achieving anesthesia of the upper airways for awake endotracheal intubation.Methods:This is a randomized, assessor-blinded, prospective study. From Jun. 1^st, 2019 to Aug. 1^st, 2019, patients scheduled for either endoscopic submucosal dissection or peroral endoscopic myotomy were enrolled and randomly allocated into two groups after obtaining written informed consent: patients allocated to novel awake intubation care (Group N-AIC) received a single administration of oral dyclonine hydrochloride mucilage, whereas patients allocated to standard awake intubation care (Group S-AIC) received three oropharyngeal tetracaine sprays before transcricoid tetracaine injection before awake intubation. Mean arterial pressure (MAP), which was the primary outcome of this study, as well as heart rate (HR) were recorded throughout the procedure and compared between the two groups. Feeling of numbness, nausea, and intubation conditions after topical anesthesia were also assessed.Results:Sixty patients were enrolled and completed the study. Baseline MAP and HR were similar between the two groups. However, hemodynamic responses to intubation and gastrointestinal endoscopy, especially MAP, were significantly less elevated in Group N-AIC. The degree of numbness of the oropharyngeal mucosa after topical anesthesia did not differ between the two groups, neither did the feeling of nausea during laryngoscopy. The amount of pharyngeal secretions before intubation was less in Group N-AIC. Total intubation time was significantly shorter in Group N-AIC when compared to Group S-AIC (18.4 ± 2.86 vs. 22.3 ± 6.47, P < 0.05). Extubation bucking was significantly less frequent in Group N-AIC (13.3% vs. 76.7%). Patients received in Group N-AIC had a lower rate of post-extubation sore throat compared to Group S-AIC (6.7% vs. 43.3%). No adverse side effects attributable to either tetracaine or dyclonine were observed in this study.Conclusions:In awake endotracheal intubation, novel care using oral dyclonine hydrochloride mucilage can provide more favorable mucosal anesthesia and better intubation conditions compared to standard of care practice using oropharyngeal tetracaine spray.Chinese Clinical Trial Registry: ChiCTR1900023151 ( http://www.chictr.org )

Propofol is a widely used intravenous anesthetic agent in sedation and general anesthesia. To improve the safety and maintain the depth of anesthesia, it is important to develop a rapid, sensitive, and reliable method to monitor the concentration of propofol in blood during anesthesia continuously. Here, we present a novel strategy based on paper spray ionization-mass spectrometry (PSI-MS) to detect propofol. Samples (in 10 μL) were mixed with methanol as protein precipitation solvent and 2,6-dimethylphenol as internal standard. Protein micro-precipitation was achieved with methanol by vortexing and centrifuging for 5 s each, and propofol was extracted to the supernatant. PSI-MS was performed in negative ionization mode, and MS signal lasted for 1 min. The analysis of a single sample was completed within 2 min. The area ratios of propofol to internal standard were calculated for quantification. Limit of detection of 5.5 ng mL⁻¹ and limit of quantification of 18.2 ng mL⁻¹ were achieved for propofol in whole blood. Calibration curve was linear in the range of 0.02–10 μg mL⁻¹. The developed method was used successfully in monitoring the propofol concentration in 3 patients’ whole blood during anesthesia, showing its further application in controlling and feeding-back target concentration infusion. Graphical abstract