Spontaneous Breathing Research Articles

Changes in blood gas in supine and prone positions in percutaneous stone surgery: does position have any advantage for hemodynamics?

To evaluate whether different positions are advantageous for hemodynamics and respiratory balance in patients undergoing percutaneous nephrolithotomy (PCNL) procedures. Pre- and postoperative arterial blood gas data obtained during spontaneous breathing for 67 prone (Group 1) and 56 supine (Group 2) patients undergoing PCNL were analyzed. Additionally data on all patients' gender, age, body mass index, stone size, access and surgical duration, volume of irrigation fluid, length of hospital stay, requirement for blood transfusion, and residual stones were recorded: There were no differences between the groups in terms of age, stone size, operation time, access time, radiation exposure, transfusion requirements, stone-free rate, and length of hospitalization. A statistically significant pH decrease was observed in both groups in the postoperative period (p = 0.001 and p = 0.001, respectively). There was a statistically significant increase in pCO2 values in both groups in the postoperative period (p = 0.001 and p = 0.024, respectively), and that increase did not differ significantly between the groups (p = 0.624). A statistically significant decrease in pO2 and SpO2 values was observed in both groups in the postoperative period compared to the preoperative period. Again, no statistical difference was observed between the groups for these values. There was a statistically significant decrease in bicarbonate in both groups period (p < 0.001 and p = 0.001, respectively). Hemodynamics and the respiratory balance of the patient are impaired in both prone and supine positions. Neither position is superior to the other in this respect.

High frequency percussive ventilation in acute respiratory failure

IntroductionHigh-Frequency Percussive Ventilation (HFPV) is a ventilation mode characterised by high-frequency breaths. This study investigated the impact of HFPV on gas exchange and clinical outcomes in acute respiratory failure (ARF) patients during spontaneous breathing, non-invasive ventilation (NIV), and invasive mechanical ventilation (iMV).MethodsThis systematic review included randomised and nonrandomised studies up to August 2023. Inclusion criteria focused on adult ARF patients, HFPV application, comparisons with other ventilation modes, and outcomes related to oxygenation and clinical parameters. A pooled data analysis was performed comparing HFPV with iMV concerning gas exchange, pulmonary infection, and mortality.ResultsOf the 51 identified records, 29 met the inclusion criteria. HFPV was safely and effectively applied to ARF patients during spontaneous breathing or NIV, improving oxygenation. For patients who underwent iMV, HFPV significantly enhanced oxygenation and the arterial partial pressure of carbon dioxide, reduced pulmonary infection occurrence, and improved survival. Barotrauma rates were not elevated with HFPV, and hemodynamic stability remained unaffected. HFPV was also utilised in patients undergoing Extra-Corporeal Membrane Oxygenation, resulting in improved lung recruitment and oxygenation.ConclusionHFPV had favourable effects on physiological and certain clinical outcomes in ARF patients. However, the overall evidence quality remains weak, necessitating large-scale randomised controlled trials for definitive conclusions.

Ability of parasternal intercostal muscle thickening fraction to predict reintubation in surgical patients with sepsis

ObjectivesWe aimed to evaluate the ability of the parasternal intercostal (PIC) thickening fraction during spontaneous breathing trial (SBT) to predict the need for reintubation within 48 h after extubation in surgical patients with sepsis.MethodsThis prospective observational study included adult patients with sepsis who were mechanically ventilated and indicated for SBT. Ultrasound measurements of the PIC thickening fraction and diaphragmatic excursion (DE) were recorded 15 min after the start of the SBT. After extubation, the patients were followed up for 48 h for the need for reintubation. The study outcomes were the ability of the PIC thickening fraction (primary outcome) and DE to predict reintubation within 48 h of extubation using area under receiver characteristic curve (AUC) analysis. The accuracy of the model including the findings of right PIC thickening fraction and right DE was also assessed using the current study cut-off values. Multivariate analysis was performed to identify independent risk factors for reintubation.ResultsWe analyzed data from 49 patients who underwent successful SBT, and 10/49 (20%) required reintubation. The AUCs (95% confidence interval [CI]) for the ability of right and left side PIC thickening fraction to predict reintubation were 0.97 (0.88–1.00) and 0.96 (0.86–1.00), respectively; at a cutoff value of 6.5–8.3%, the PIC thickening fraction had a negative predictive value of 100%. The AUCs for the PIC thickening fraction and DE were comparable; and both measures were independent risk factors for reintubation. The AUC (95% CI) of the model including the right PIC thickening fraction > 6.5% and right DE ≤ 18 mm to predict reintubation was 0.99 (0.92–1.00), with a positive predictive value of 100% when both sonographic findings are positive and negative predictive value of 100% when both sonographic findings are negative.ConclusionsAmong surgical patients with sepsis, PIC thickening fraction evaluated during the SBT is an independent risk factor for reintubation. The PIC thickening fraction has an excellent predictive value for reintubation. A PIC thickening fraction of ≤ 6.5–8.3% can exclude reintubation, with a negative predictive value of 100%. Furthermore, a combination of high PIC and low DE can also indicate a high risk of reintubation. However, larger studies that include different populations are required to replicate our findings and validate the cutoff values.

Weaning from mechanical ventilation during myasthenic crisis, a monocentric retrospective study

Mechanical ventilation in myasthenic crisis is not standardized and is at high risk of failure. We investigated liberation from mechanical ventilation during myasthenic crisis using a prolonged spontaneous breathing trials (SBT) and sequential pulmonary function tests (PFT). In this retrospective monocenter study, we included patients admitted for a first episode of myasthenic crisis between January 2001 and January 2018. The primary outcome was the incidence of weaning failure upon first extubation in our cohort of patients with MC. Secondary objectives were to determine risk factors and outcome associated with weaning failure upon first extubation in MC. We also compared the characteristics of patients with prolonged weaning. 126 episodes of MC were analyzed. Patient’s age was 64 [42–76] years with 72/126 (56.5%) being women. The median delay between weaning initiation and first extubation was 6 [3–10] days and the median total length of MV was 14 [10–23] days. 118/126 (93.7%) patients underwent prolonged SBT of 8 h or more prior to first extubation. The overall weaning failure rate was 18/126 (14.3%). Extubation was more often successful when the factor precipitating the myasthenic crisis was identified (86/108 (79.6%) vs. 8/18 (44.4%); p = 0.004), whereas PFT was similar in failure or successes. Most weaning failures upon first extubation attempt (11/18; 61%) were attributed to an insufficient stabilization of myasthenia gravis. Duration of mechanical ventilation, an infectious trigger and maximal inspiratory pressure upon intubation were independent risk factors for prolonged weaning. In myasthenic crisis, a standardized protocol including prolonged SBT and respiratory function tests might improve the success of first extubation without prolonging mechanical ventilation. The results of this single center study warrant further evaluation in interventional trials.

Imitating the respiratory activity of the brain stem by using artificial neural networks: exploratory study on an animal model of lactic acidosis and proof of concept.

Artificial neural networks (ANNs) are versatile tools capable of learning without prior knowledge. This study aims to evaluate whether ANN can calculate minute volume during spontaneous breathing after being trained using data from an animal model of metabolic acidosis. Data was collected from ten anesthetized, spontaneously breathing pigs divided randomly into two groups, one without dead space and the other with dead space at the beginning of the experiment. Each group underwent two equal sequences of pH lowering with pre-defined targets by continuous infusion of lactic acid. The inputs to ANNs were pH, ΔPaCO2 (variation of the arterial partial pressure of CO2), PaO2, and blood temperature which were sampled from the animal model. The output was the delta minute volume (ΔVM), (the change of minute volume as compared to the minute volume the animal had at the beginning of the experiment). The ANN performance was analyzed using mean squared error (MSE), linear regression, and the Bland-Altman (B-A) method. The animal experiment provided the necessary data to train the ANN. The best architecture of ANN had 17 intermediate neurons; the best performance of the finally trained ANN had a linear regression with R2 of 0.99, an MSE of 0.001 [L/min], a B-A analysis with bias ± standard deviation of 0.006 ± 0.039 [L/min]. ANNs can accurately estimate ΔVM using the same information that arrives at the respiratory centers. This performance makes them a promising component for the future development of closed-loop artificial ventilators.

Anesthetic Management of a Patient with Saber-Sheath Trachea

Saber-sheath trachea is a deformation of the trachea characterized by a tracheal index of less than 0.67, commonly found in patients with chronic obstructive pulmonary disease (COPD). This condition can lead to symptoms such as shortness of breath, coughing, and recurrent respiratory infections, which may necessitate surgical intervention. We present the case of a 72-year-old male with a left upper pulmonary lobe tumor scheduled for thoracoscopic lobectomy. The patient exhibited severe emphysema and had a tracheal index of 0.28, indicating a significantly narrowed intrathoracic trachea. Preoperative assessments revealed stable vital signs and low risk for perioperative complications, allowing for standard noninvasive monitoring during the procedure. Anesthesia was induced while maintaining spontaneous breathing using inhalation anesthetics. A left-sided double-lumen endotracheal tube was successfully placed for lung isolation. Throughout the surgery, airway pressures remained below 20 cm H&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;O, and the patient tolerated ventilation well. Following the procedure, fiberoptic bronchoscopy confirmed the absence of airway complications. The patient experienced a smooth recovery, was discharged after 6 days, and reported feeling well at the 3-month follow-up. This case underscores the importance of careful anesthetic management in patients with saber-sheath trachea undergoing thoracic surgery.

Sex-based Differences in the Use of Best Practices in Mechanically Ventilated Adults in the Intensive Care Unit: An Analysis of the Toronto Multi-center iCORE Database.

Rationale Patients who are critically ill and require admission to an Intensive Care Unit (ICU) should receive the same quality of care regardless of their sex. Objectives To determine, using population data from a multicenter database in Ontario, Canada, whether sex is associated with differences in the use of 8 best practices and other interventions during the ICU care of mechanically ventilated women and men. Methods Using a cohort of patients receiving mechanical ventilation in 8 intensive care units, our co-primary outcomes were differences in compliance with 8 evidence-based practices between women and men (opioid administration, use of continuous sedation or opioids, sedation minimization; spontaneous breathing trials; stress ulcer prophylaxis; deep venous thrombosis prophylaxis; physical restraint; and mobilization). All analyses were adjusted for confounders using logistic regression and restricted to patients eligible for each best practice. Measurements and Main Results We included 19070 (11910 men, 7160 women) patients who were mechanically ventilated for more than 4 hours. Men and women had similar opioid administration, sedation minimization, stress ulcer prophylaxis, DVT prophylaxis, and mobilization. Women were less likely to receive continuous infusions of sedation or opioids than men (adjusted OR 0.86, 95% CI 0.78, 0.95), and less likely to be physically restrained (adjusted OR 0.82, 95% CI 0.74, 0.89). Conclusions: In this cohort of mechanically ventilated patients, the use of evidence-based practices was similar between women and men, except for a higher utilization of continuous sedative or opioid infusions and physical restraints in men.

Predicting Successful Weaning through Sonographic Measurement of the Rapid Shallow Breathing Index.

Background: Diaphragmatic dysfunction correlates with weaning failure, highlighting the need to independently assess the diaphragm's effects on weaning. We modified the rapid shallow breathing index (RSBI), a predictor of successful weaning, by incorporating temporal variables into existing ultrasound-derived diaphragm index to create a simpler index closer to tidal volume. Methods: We conducted a prospective observational study of patients who underwent a spontaneous breathing trial in the medical intensive care unit (ICU) at Severance Hospital between October 2022 and June 2023. Diaphragmatic displacement (DD) and diaphragm inspiratory time (Ti) were measured using lung ultrasonography. The modified RSBI was defined as follows: respiratory rate (RR) divided by DD was defined as D-RSBI, and RR divided by the sum of the products of DD and Ti on both sides was defined as DTi-RSBI. Results: Among the sonographic indices, DTi-RSBI had the highest area under the receiver operating characteristic (ROC) curve of 0.774 in ROC analysis, and a correlation was found between increased DTi-RSBI and unsuccessful extubation in a multivariable logistic regression analysis (adjusted odds ratio 0.02, 95% confidence interval 0.00-0.97). Conclusions: The DTi-RSBI is beneficial in predicting successful weaning in medical ICU patients.

Ultrasound evaluation of cardiac and diaphragmatic function at different positions during a spontaneous breathing trial predicting extubation outcomes: a retrospective cohort study

BackgroundThe ratio (E/Ea) of mitral Doppler inflow velocity to annular tissue Doppler wave velocity by transthoracic echocardiography and diaphragmatic excursion (DE) by diaphragm ultrasound have been confirmed to predict extubation outcomes. However, few studies focused on the predicting value of E/Ea and DE at different positions during a spontaneous breathing trial (SBT), as well as the effects of △E/Ea and △DE (changes in E/Ea and DE during a SBT).MethodsThis study was a reanalysis of the data of 60 difficult-to-wean patients in a previous study published in 2017. All eligible participants were organized into respiratory failure (RF) group and extubation success (ES) group within 48 h after extubation, or re-intubation (RI) group and non-intubation (NI) group within 1 week after extubation. The risk factors for respiratory failure and re-intubation including E/Ea and △E/Ea, DE and △DE at different positions were analyzed by multivariate logistic regression, respectively. The receiver operating characteristic (ROC) curves of E/Ea (septal, lateral, average) and DE (right, left, average) were compared with each other, respectively.ResultsOf the 60 patients, 29 cases developed respiratory failure within 48 h, and 14 of those cases required re-intubation within 1 week. Multivariate logistic regression showed that E/Ea were all associated with respiratory failure, while only DE (right) and DE (average) after SBT were related to re-intubation. There were no statistic differences among the ROC curves of E/Ea at different positions, nor between the ROC curves of DE. No statistical differences were shown in △E/Ea between RF and ES groups, while △DE (average) was remarkably higher in NI group than that in RI group. However, multivariate logistic regression analysis showed that △DE (average) was not associated with re-intubation.ConclusionsE/Ea at different positions during a SBT could predict postextubation respiratory failure with no statistical differences among them. Likewise, only DE (right) and DE (average) after SBT might predict re-intubation with no statistical differences between each other.

Application of combined anesthesia with spontaneous breathing in the surgery of intertrochanteric fracture of femur in elderly patients.

This study aims to investigate the feasibility and safety of combined anesthesia with spontaneous breathing in the operation of intertrochanteric fracture of femur in the elderly. Between January 2020 and January 2023, a total of 141 elderly patients (45 males, 96 females; mean age: 72.5±6.8 years; range, 65 to 87 years) who underwent proximal femoral nail anti-rotation (PFNA) surgery for intertrochanteric fracture of femur were included in this single-blind, prospective, randomized-controlled study. The patients were randomly divided into three groups. Group A (experimental group) was a general anesthesia with laryngeal mask airway (LMA) group preserving spontaneous breathing, Group B (control group 1) was a general anesthesia with LMA group for mechanical ventilation, and Group C (control group 2) was a tracheal intubation anesthesia group for mechanical ventilation. The differences of related indexes among the three groups were compared. The mean onset time of anesthesia (6.23±1.45 vs. 12.78±2.78 vs. 13.73±2.43 min), postoperative recovery time of consciousness (8.13±0.83 vs. 11.34±0.89 vs. 12.45±0.86 min), and postoperative complete awakening time (10.45±2.34 vs. 18.87±2.56 vs. 19.62±2.93 min) were significantly shorter in Group A than in Groups B and C (p<0.05). The duration of analgesic effect was longer in Group A than in Groups B and C (p<0.05). After anesthesia, the Ramsay Sedation Scale and Visual Analog Scale (VAS) scores were significantly lower in Group A than the other groups (p<0.05). The mean Mini-Mental State Examination (MMS) scores were significantly higher in Group A than in Groups B and C (p<0.05). Hemodynamic parameters showed that blood pressure, heart rate, cardiac output, and cardiac index (CI) levels were significantly higher in Group A than the other groups (p<0.05). Our study results indicate that combined anesthesia preserving spontaneous breathing is safe and feasible in the operation of intertrochanteric fracture of femur in the elderly, with faster anesthesia recovery than the mechanical ventilation group.

A Pediatric Bench Model of Continuous Albuterol Delivery Using Heliox.

The optimal setup for continuously administering albuterol with heliox remains unclear, especially for pediatric patients. This study aimed to evaluate the efficiency of continuous albuterol delivery with heliox using different nebulizer setups in a pediatric model. A pediatric manikin with simulated spontaneous breathing was used to receive continuous albuterol (20 mg/h) with heliox (80/20) in 3 setups: (1) The MiniHEART nebulizer, driven by oxygen at 3 L/min, was attached to a Y-piece, linking to a non-rebreather mask and a valved reservoir with 11 L/min heliox; (2) a vibrating mesh nebulizer (VMN) placed at the humidifier inlet of high-flow nasal cannula (HFNC) with 11 L/min heliox and the manikin's mouth sealed; and (3) a VMN placed between a valved reservoir with 11 L/min heliox and a non-rebreather mask. Both tight-fitting and loose-fitting mask configurations were tested in the setup with vibrating mesh nebulizer and mask. Heliox of 70/30 was tested with a VMN and a loose-fitting mask. Albuterol was delivered continuously to the nebulizer via an infusion pump at 8 mL (20 mg)/h for each 20-min run and each experiment was repeated five times. A collecting filter placed between the manikin's trachea and lung model was removed after each run, and the drug was eluted and assayed via ultraviolet spectrophotometry (276 nm). During continuous albuterol nebulization using heliox, the VMN either in line with HFNC or with a tight-fitting mask achieved the highest and similar inhaled dose (8.5 ± 0.4 vs 8.8 ± 0.7%, P = .35), while the MiniHEART nebulizer yielded the lowest aerosol deposition (1.5 ± 0.2%). The inhaled dose was lower with the loose-fitting mask than with the tight-fitting mask (5.9 ± 0.9 vs 8.8 ± 0.7%, P=.009), and heliox of 80/20 delivered a higher inhaled dose than heliox of 70/30 (5.9 ± 0.9 vs 3.9 ± 0.4%, P=.009). When administering continuous albuterol with heliox in a pediatric model, utilizing a VMN in line with HFNC during closed-mouth breathing yielded a higher inhaled dose compared to both the MiniHEART nebulizer and VMN with a loose-fitting mask.

Spontaneous breathing trial: the key to a successful extubation

Spontaneous breathing trial: the key to a successful extubation

Efficacy and Safety of Dexmedetomidine in the Prone Position in Elderly Patients with Pneumonia: A Prospective, Double-Blind, Randomized Controlled Study.

We aimed to identify a safe and effective method to assist older adults with pneumonia in tolerating the prone position for a longer duration. This was a randomized, controlled, double-blinded study performed at the Shanghai Fourth People's Hospital. Eighty patients with pneumonia aged ≥ 65years were included. The patients were able to spontaneous breath in the prone position and were administered intravenous dexmedetomidine or an isotonic sodium chloride solution. The cumulative daily durations of prone positioning for all patients in the two groups were recorded. The primary outcome was the percentage of patients who completed ≥ 9h/day in the prone position. The secondary outcomes included the incidence of complications in the prone position and patient outcomes. Eighty patients were included (average age: 79.6 ± 8.9years). The percentage of patients who completed ≥ 9h/day in the prone position was significantly higher in the dexmedetomidine group than in the placebo group (P = 0.011). The percentage of patients who completed ≥ 12h/day in the prone position was also significantly greater in the dexmedetomidine group than in the placebo group (P = 0.008). There were no significant differences in other variables between the two groups. The results of this study demonstrate that intravenous dexmedetomidine injection can significantly prolong the duration of spontaneous breathing in the prone position in elderly pneumonia patients without obvious adverse events. We provide a safe and effective method to help patients with pneumonia, especially those with delirium or cognitive impairment, who cannot tolerate the length of time needed for spontaneous breathing in the prone position to be effective. The study was registered with the Chinese Clinical Trial Center (registration number: ChiCRT2300067383) on 2023-01-05.

Effects of increasing tidal volume and end-expiratory lung volume on induced bronchoconstriction in healthy humans

BackgroundIncreasing functional residual capacity (FRC) or tidal volume (VT) reduces airway resistance and attenuates the response to bronchoconstrictor stimuli in animals and humans. What is unknown is which one of the above mechanisms is more effective in modulating airway caliber and whether their combination yields additive or synergistic effects. To address this question, we investigated the effects of increased FRC and increased VT in attenuating the bronchoconstriction induced by inhaled methacholine (MCh) in healthy humans.MethodsNineteen healthy volunteers were challenged with a single-dose of MCh and forced oscillation was used to measure inspiratory resistance at 5 and 19 Hz (R5 and R19), their difference (R5-19), and reactance at 5 Hz (X5) during spontaneous breathing and during imposed breathing patterns with increased FRC, or VT, or both. Importantly, in our experimental design we held the product of VT and breathing frequency (BF), i.e, minute ventilation (VE) fixed so as to better isolate the effects of changes in VT alone.ResultsTripling VT from baseline FRC significantly attenuated the effects of MCh on R5, R19, R5-19 and X5. Doubling VT while halving BF had insignificant effects. Increasing FRC by either one or two VT significantly attenuated the effects of MCh on R5, R19, R5-19 and X5. Increasing both VT and FRC had additive effects on R5, R19, R5-19 and X5, but the effect of increasing FRC was more consistent than increasing VT thus suggesting larger bronchodilation. When compared at iso-volume, there were no differences among breathing patterns with the exception of when VT was three times larger than during spontaneous breathing.ConclusionsThese data show that increasing FRC and VT can attenuate induced bronchoconstriction in healthy humans by additive effects that are mainly related to an increase of mean operational lung volume. We suggest that static stretching as with increasing FRC is more effective than tidal stretching at constant VE, possibly through a combination of effects on airway geometry and airway smooth muscle dynamics.

High Flow Nasal Cannula Versus Conventional Oxygen Therapy and Incidence of Post-Extubation Airway Obstruction in PICU: An Open-Label Randomized Controlled Trial (HiFloCOT-PICU Trial).

To study the impact of high flow nasal cannula (HFNC) vs. conventional oxygen therapy (COT) (by simple nasal cannula) as respiratory support after extubation on the rates of post-extubation airway obstruction (PEAO) among mechanically ventilated critically ill children. This open-label randomized controlled trial was conducted in pediatric intensive care unit (PICU) of a tertiary care teaching hospital in North India over a period of 7 mo (11 August 2021 to 10 March 2022). Children aged 3 mo to 12 y who required invasive mechanical ventilation for > 72h and had passed spontaneous breathing trial (ready for extubation) were enrolled and randomized by computer generated block randomization to receive HFNC or COT after extubation. Primary outcome was rate of PEAO (assessed by modified Westley croup score, mWCS) within 48h of extubation; and secondary outcomes were rate and number of adrenaline nebulization, treatment failure (requiring escalation of respiratory support), extubation failure, adverse events, and length of PICU stay in two groups. During the study period, 116 children were enrolled (58 each in HFNC and COT groups). There was no difference in rate of PEAO (55% vs. 51.7%, respectively), need of adrenaline nebulization, extubation failure, adverse events, and duration of PICU stay in two groups. However, the HFNC group had significantly lower rates of treatment failure (27.6% vs. 48.3%, p = 0.02). The rate of PEAO was similar in HFNC and COT groups. However, HFNC group had significantly lower rate of treatment failure requiring escalation of respiratory support.

One‐way valves in breathing tubing reduce dead space during spontaneous breathing in anesthetized piglets

AbstractThe circle breathing system was unsafe for spontaneous breathing because of hypercapnia during anesthesia. Few studies have examined the minimizing dead space in breathing tubing. This study investigated one‐way valves in the breathing tubing during spontaneous breathing in piglets. Six female piglets aged 68–71 days spontaneously breathed sevoflurane for 4 h randomly via traditional or anti‐rebreathing tubing. Arterial carbon dioxide tension (PaCO2) and respiratory characteristics were used to assess spontaneous breathing efficiency. mRNA‐based methods, immunohistochemistry, and histology were used to assess the lungs. After induction, all piglets had mild hypercapnia. Those who breathed via traditional tubing experienced severe hypercapnia and required assisted ventilation (mean [95% confidence interval for mean]: 3 [0.5; 5.5] times) over 4 h. Piglets who breathed via anti‐rebreathing tubing were able to normalize without assisted ventilation in less than 3 h and maintained. PaCO2 was higher in the traditional group than the anti‐rebreathing group at 3 and 4 hours (46.3 [42.1; 50.5] vs. 38.3 [34.1; 42.5] mmHg, p = 0.020; 46.3 [42.6; 50.0] vs. 40.7 [37.0; 44.4] mmHg, p = 0.040). However, one‐way valves increased resistance to breathing. For the lungs, mRNA‐based methods indicated higher expressions of cyclin‐dependent kinase, cell division cycle 20, and cyclin B2 in the traditional group; immunohistochemistry identified higher expression of phosphorylated histone 2AX in the traditional group; histology showed similar damage between the groups. These findings suggest that one‐way valves inside breathing tubing reduced dead space during spontaneous breathing and enhanced inhalation anesthesia advantages in the circle breathing system.

Thoracoscopic wedge resection of the upper lobe of the left lung achieved by a new approach of laryngeal mask general anesthesia with preservation of spontaneous breathing: A case report.

General laryngeal mask anesthesia with the preservation of spontaneous breathing has accelerated the advancement of the enhanced recovery after surgery concept in thoracoscopic surgery. However, the need for increased doses of anesthetic drugs to reduce laryngeal mask airway (LMA) stimulation poses challenges due to the increased risk of hypotension, respiratory depression, susceptibility to hypoxemia, and carbon dioxide retention, particularly in the lateral position. During the perioperative period, reducing the dose of anesthetic drugs while simultaneously improving LMA tolerance and preventing circulatory and respiratory depression poses a challenge. The patient was diagnosed with a nodule in the upper lobe of the left lung. In this case, we chose remimazolam sedation, which mildly inhibits circulatory respiration, and used mucosal surface anesthesia in the pharynx. This approach improved the patient's tolerance to LMA, reduced the dose of anesthetic drugs, and facilitated the successful thoracoscopic wedge resection of the upper lobe of the left lung with preservation of spontaneous respiration. During 2 weeks follow-up, the patient recovered satisfactorily and did not report any discomfort. We used pharyngeal mucosal surface anesthesia and thoracic paravertebral nerve block in combination with remimazolam sedation to provide precise analgesia, moderate sedation, and successful LMA general anesthesia with preservation of spontaneous respiration in patients undergoing thoracoscopic pulmonary wedge resection.

Non-Intubated Video-assisted Thoracoscopic Surgery (niVATS)

Non-intubated minimally invasive lung surgery garnered renewed interest during the past decade and many centers across the country successfully implemented the technique for minor procedures like pleurodesis or wedge resection. Anatomical lung resection under spontaneous breathing still is considered as challenging, and as existing data to support it is conflicting and confusing, the approach remains limited to few dedicated outfits. We seek to present the historical perspective, critically report potential advantages and limitations of the technique and hand out a guideline that might prove to be helpful in building up a dedicated program.

Determining the optimum high-flow nasal cannula flow rate to achieve the desired fraction of inspired oxygen: A bench study

BackgroundPurpose: High-flow nasal cannula (HFNC) has many benefits in various clinical conditions. The original hypothesis suggests that the high and constant fraction of inspired oxygen (FiO2) is one of the main physiological effects. However, increasing evidence shows that there is a gap between the actual FiO2 and administered FiO2. We aimed to determine the actual FiO2 under different respiratory conditions and develop a regression model using a spontaneous breathing lung model. MethodsA spontaneous breathing simulation model was built using an airway manikin and a model lung. The FiO2 was measured under different respiratory conditions with varying tidal volumes and respiratory and HFNC flow rates. The relationships between the respiratory parameters and actual FiO2 were determined and used to build the predictive model. ResultsThe actual FiO2 was negatively correlated with respiratory rate and tidal volume and positively correlated with HFNC flow. The regression model could not be developed using simple respiratory parameters. Therefore, we introduced a new variable, defined as flow ratio, which equaled the HFNC flow divided by inspiratory flow. Our equation demonstrated that the actual FiO2 was mainly determined by the flow ratio in a non-linear relationship. Accordingly, a flow ratio greater than 1 did not ensure a constant high FiO2, whereas a flow ratio >1.435 could produce FiO2 >0.9. ConclusionThe FiO2 during HFNC was not constant even at sufficiently high oxygen flow compared with inspiratory flow. The predictive model showed that the actual FiO2 was mainly determined by the flow ratio.

A case of opioid-induced rigidity requiring naloxone administration at the time of anesthesia emergence

BackgroundOpioid-induced rigidity is typically observed during rapid administration of fentanyl. Herein, we present a case in which rigidity occurred after reversal of rocuronium during emergence from anesthesia.Case presentationA 73-year-old man underwent video-assisted partial lung resection. General anesthesia was induced with propofol, remimazolam, remifentanil, and rocuronium. Fentanyl was administered early during anesthesia. The surgery was completed without complications, and sugammadex sodium was administered for rocuronium reversal. The patient became agitated, but spontaneous breathing was maintained; therefore, the intratracheal tube was removed after the administration of flumazenil. The patient developed stiffness in the neck and jaw muscles along with remarkable skeletal muscle contractions. Dramatic improvement was observed immediately after administration of naloxone.ConclusionsEven as the simulated effect site concentration of fentanyl decreases during anesthesia emergence, opioid-induced rigidity may still occur. Rapid reversal of remimazolam by flumazenil might have contributed to the rigidity in this case.