Increased Airway Pressure Research Articles

Changes of endotracheal tube cuff pressure and its indicators in laparoscopic resection of colorectal neoplasms: an observational prospective clinical trial

BackgroundLaparoscopic surgery is a popular alternative for resection of colorectal neoplasms. Carbon dioxide pneumoperitoneum and Trendelenburg positioning in procedure can significantly increase airway pressure, when endotracheal tube cuff pressure is not monitored. This prospective observational study aimed to evaluate indicators, changes and its correlation factors of endotracheal tube cuff pressure during laparoscopic resection of colorectal neoplasms.Methods122 patients scheduled for laparoscopic resection of colorectal neoplasms under propofol/remifentanil total intravenous anesthesia with orotracheal intubation were included. Tracheal tube cuff pressure was monitored continuously by calibrated pressure transducers. The ability of several predictors to predict out-of-range tracheal tube cuff pressure at different time points and its correlation factors were assessed.ResultsROC analysis showed that waist-to-hip ratio has the highest AUC for predicting out-of-range tracheal cuff pressure (AUC: 0.86 [95% CI: 0.77–0.95]); Tracheal tube cuff pressure provided by palpation was 41.0 (29.0−53.3) cmH20. Cuff pressure was 33.7 ± 2.9 cmH20 at 15 min and comparable at 30 and 45 min after insufflation, all values were significantly higher than 25 cmH20 (p < 0.001). Multiple linear regression showed tracheal tube cuff pressure was associated with peak airway pressure (p < 0.001).ConclusionsPatients with normal BMI undergoing laparoscopic resection of colorectal neoplasms require continuous monitoring and timely adjustments of tracheal tube cuff pressure. Compared with BMI, waist-to-hip ratio is a better predictor of out-of-range tracheal tube cuff pressure.Trial registrationChinese Clinical Trial Registry, identifier: ChiCTR2100054089, Date: 08/12/2021.

The Impact of Pneumoperitoneum on Mean Expiratory Flow Rate: Observational Insights from Patients with Healthy Lungs.

Surgical pneumoperitoneum (PP) significantly impacts volume-controlled ventilation, characterized by reduced respiratory compliance, elevated peak inspiratory pressure, and an accelerated expiratory phase due to an earlier onset of the airway pressure gradient. We hypothesized that this would shorten expiratory time, potentially increasing expiratory flow rate compared to pneumoperitoneum conditions. Calculations were performed to establish correlations between respiratory parameters and the mean increase in expiratory flow rate relative to baseline. Mechanical ventilation parameters were recorded for 67 patients both pre- and post-PP. Ventilator settings were standardized with a tidal volume of 6 mL/kg, a respiratory rate of 12 breaths per minute, a PEEP of 3 cmH2O, an inspiratory time of 2 s, and an inspiratory-to-expiratory ratio of 1:1.5 (I:E). The application of PP increased both peak inspiratory pressure and mean expiratory flow rate by 28% compared to baseline levels. The elevated intra-abdominal pressure of 20 cmH2O resulted in a 34% reduction in dynamic chest compliance, a 50% increase in elastance, and a 20% increase in airway resistance. The mean expiratory flow rate increments relative to baseline showed a significant negative correlation with elastance (p = 0.0119) and a positive correlation with dynamic compliance (p = 0.0028) and resistance (p = 0.0240). A PP of 20 cmH2O resulted in an increase in the mean expiratory flow rate in the conventional I:E ratio in the volume-ventilated mode. PP reduces lung and chest wall compliance by elevating the diaphragm, compressing the thoracic cavity, and increasing airway pressures. Consequently, the lungs and chest wall stiffen, requiring greater ventilatory effort and accelerating expiratory flow due to increased airway resistance and altered pulmonary mechanics. Prolonging the inspiratory phase through I:E ratio adjustment helps maintain peak inspiratory pressures closer to baseline levels, and this method enhances the safety and efficacy of mechanical ventilation in maintaining optimal respiratory function during laparoscopic surgery.

Dynamic shunt flow alterations through patent foramen ovale during off-pump coronary artery bypass grafting induced by airway pressure changes: a case report.

Interatrial right-to-left shunt flow through a patent foramen ovale (PFO) can be caused by changes in heart position for anastomosis during off-pump coronary artery bypass (OPCAB). We herein present a case in which the direction of PFO shunt flow changed with heart position during OPCAB and the ventilation settings after sternal closure. A 66-year-old man with interstitial pneumonia underwent OPCAB. Preoperative transesophageal echocardiography revealed right-to-left shunt flow through a PFO induced by the Valsalva maneuver. During OPCAB, heart displacement resulted in right-to-left shunting and acute hypoxemia, which quickly improved with increase of inspired oxygen fraction. After chest closure, bidirectional shunt flow developed under increased airway pressure. Vigilant intraoperative monitoring with TEE and postoperative airway pressure management are important to address shunt flow and hypoxemia due to PFO.

Activation of Automatic Tube Compensation Mode Attenuates Auto-PEEP in Chronic Obstructive Pulmonary Disease Patients.

Dynamic hyperinflation in chronic obstructive pulmonary disease (COPD) results in intrinsic positive end-expiratory pressure (auto-PEEP). Automatic tube compensation (ATC) is used to increase airway pressure in COPD and overcome endotracheal tube (ETT)-imposed respiratory workload. We aim to investigate effects of ATC activation on auto-PEEP decrease in COPD. ATC was activated three times a day (1 min duration) in the morning, evening, and night shift. Auto-PEEP was measured for the 1 min period (every 6 s) following ATC activation. Linear mixed model (LMM) was used to measure changes in auto-PEEP and compare with baseline value. Age, gender, and COPD types were inserted in model as covariates and analyzed using SPSS. A total of 60 patients including COPD (n = 40) and COPD with exacerbation (n = 20) were included. Compared with exacerbated COPD, baseline auto-PEEP in COPD was significantly lower in morning (p = 0.011), evening (p = 0.043), and night shift (p = 0.007). After ATC activation, auto-PEEP decreased significantly in COPD in morning, evening, and night (p = 0.001), but magnitude of this decrease was notably larger in COPD than in exacerbated COPD (p = 0.001). Moreover, there was a significant relationship between COPD exacerbation and changes in auto-PEEP in morning (β = -0.27, p = 0.001), evening (β = -0.16, p = 0.001), and night (β = -0.26, p = 0.001). The activation of ATC mode in COPD patients under mechanical ventilation could decrease the value of auto-PEEP. Nevertheless, COPD patients with an exacerbation appear to benefit less from ATC activation.

A Comparison of the Effects of Different Positive End-Expiratory Pressure Levels on Respiratory Parameters During Prone Positioning Under General Anaesthesia: A Randomized Controlled Trial.

Background and objective In general anesthesia, for certain surgical procedures in the prone position, patients often face increased airway pressures, reduced pulmonary and thoracic compliance, and restricted chest expansion, all of which can affect venous return and cardiac output, impacting overall hemodynamic stability. Positive end-expiratory pressure (PEEP) is used to address these issues by improving lung recruitment and ventilation while reducing stress on lung units. However, different PEEP levels also present risks such as increased parenchymal strain, higher pulmonary vascular resistance, and impaired venous return. Proper positioning and frequent monitoring are key to ensuring adequate oxygenation and minimizing complicationsarising from prolonged periods in the prone position. This study aimed to evaluate the effects of different PEEP levels (0 cmH2O, 5 cmH2O, and 10 cmH2O) in the prone position to determine the optimal setting for balancing improved oxygenation and lung recruitment against potential adverse effects. The goal is to refine individualized PEEP strategies beyond what is typically outlined in standard PEEP tables. We endeavored to examine the impact of different PEEP levels during pressure-controlled ventilation (PCV) on arterial oxygenation, respiratory parameters, and intraoperative blood loss in patients undergoing spine surgery in a prone position under general anesthesia. Methodology This randomized, single-blinded, controlled study enrolled 90 patients scheduled for elective spine fixation surgeries. Patients were randomized into three groups: Group A (PEEP 0), Group B (PEEP 5), and Group C (PEEP 10). Standardized anesthesia protocols were administered to all groups, with ventilation set to pressure-controlled mode at desired levels. PEEP levels were adjusted according to group allocation. Arterial blood gases were measured before induction, 30 minutes after prone positioning, and 30 minutes post-extubation. Arterial line insertion was performed, and dynamic compliance, mean arterial pressure (MAP), heart rate (HR), and intraoperative blood loss were recorded at regular intervals. Data were analyzed using SPSS Statistics version 21 (IBM Corp., Armonk, NY). Results Arterial oxygenation was significantly higher in Groups B (PEEP 5) and C (PEEP 10) compared to Group A (PEEP 0) at both 30 minutes post-intubation and post-extubation. Specifically, at 30 minutes post-intubation, arterial oxygenation was 142.26 ±24.7 in Group B and 154.9 ±29.88 in Group C, compared to 128.18 ±13.3 in Group A (p=0.002). Similarly, post-extubation arterial oxygenation levels were 105.1 ±8.28 for Group B and 115.46 ±15.2 for Group C, while Group A had levels of 97.07 ±9.90 (p<0.001). MAP decreased significantly in Groups B and C compared to Group A. Dynamic compliance was also improved in Groups B and C. Furthermore, intraoperative blood loss was notably lower in Group C (329.66 ±93.93) and Group B (421.16 ±104.52) compared to Group A (466.66 ±153.76), and these differences were statistically significant. Conclusions Higher levels of PEEP (10 and 5 cmH2O) during prone positioning in spine surgery improve arterial oxygenation, dynamic compliance, and hemodynamic stability while reducing intraoperative blood loss. These findings emphasize the importance of optimizing ventilatory support to enhance patient outcomes during prone-position surgeries.

The Use of Bi-Nasal Prongs for Delivery of Non-Invasive Ventilation to Foals.

Non-invasive ventilation (NIV) is a method of providing respiratory support without the need for airway intubation. The current study was undertaken to assess tolerance to bi-nasal prongs and NIV in healthy, standing, lightly sedated foals. Bi-nasal prongs were well tolerated by foals, remaining in place for the allocated five minutes in four of six unsedated foals and, subsequently, in five of six lightly sedated foals. All foals tolerated NIV through bi-nasal prongs, although increasing airway pressures were associated with increases in inspiratory volume, duration of inspiration and air leakage in most foals. These changes preceded discontinuation/intolerance of NIV on the basis of behaviour changes consistent with discomfort. Increased circuit leakage was associated with reduced return of expired air to the ventilator and increasing disparity between inspiratory and expiratory times and tidal volumes. The study results suggest that bi-nasal prongs might be suitable for NIV but that design or fitting requires further optimization and that behaviour and ventilator variables should be monitored to assess patient tolerance of the procedure.

Effect of target-controlled pressure-controlled ventilation on percutaneous nephrolithotripsy patients under general anesthesia: a retrospective study.

Prone position surgery tends to limit chest wall mobility with decreased compliance and increased airway pressure, which can increase the incidence of postoperative pulmonary complications, including atelectasis, pneumonia, and respiratory failure. There is a lack of guidelines recommending mechanical ventilation parameters in prone position surgery. The present study aimed to investigate the effect of pressure-controlled ventilation (PCV) with end-inspiratory flow rate as the target on percutaneous nephrolithotripsy patients under general anesthesia in the prone position. From January 2020 to December 2021, a total of 154 patients admitted to Sichuan Provincial Rehabilitation Hospital of Chengdu University of TCM were retrospectively enrolled. All patients received percutaneous nephrolithotripsy. According to the type of mechanical ventilation given during surgery, the patients were divided into a fixed-respiration-ratio-PCV group (n=78) and a target-controlled-PCV group (n=76). The hemodynamics, postoperative pulmonary complications (PPCs), and serum inflammation levels between the two groups were compared. The overall incidence of PPCs was significantly lower in the target-controlled-PCV group than in the fixed-respiration-ratio-PCV group (3.95% vs. 14.10%, P=0.028). There were no significant differences in peak airway pressure, airway plateau pressure, or dynamic lung compliance at T0 (P>0.05). However, at T1, T2, and T3, the peak airway pressure and airway platform pressure in the target-controlled-PCV group were significantly reduced (P<0.05), and the dynamic pulmonary compliance was significantly increased (P<0.05) compared with the fixed-respiration-ratio group. There was no significant difference in preoperative interleukin 6 (IL-6) and C-reactive protein (CRP) levels between the two groups (P>0.05). IL-6 and CRP levels at 1 and 3 days postoperatively were significantly reduced in the target-controlled-PCV group compared with the fixed-respiration-ratio-PCV group (P<0.05). Pressure-controlled ventilation with end-inspiratory flow rate as the target can reduce postoperative pulmonary complications and inflammatory levels in patients undergoing percutaneous nephrolithotripsy under general anesthesia in the prone position.

Effects of 2 modes of positive pressure ventilation on respiratory mechanics and gas exchange in foals.

Continuous positive airway pressure (CPAP) and pressure support ventilation (PSV) can improve respiratory mechanics and gas exchange, but different airway pressures have not been compared in foals. Assess the effect of different airway pressures during CPAP and PSV have on respiratory function in healthy foals with pharmacologically induced respiratory insufficiency. We hypothesized that increased airway pressures would improve respiratory mechanics and increased positive end-expiratory pressure (PEEP) would be associated with hypercapnia. Six healthy foals from a university teaching herd. A prospective, 2-phase, 2-treatment, randomized cross-over study design was used to evaluate sequential interventions in sedated foals using 2 protocols (CPAP and PSV). Outcome measures included arterial blood gases, spirometry, volumetric capnography, lung volume and aeration assessed using computed tomography (CT). Sedation and dorsal recumbency were associated with significant reductions in arterial oxygen pressure (PaO2 ), respiratory rate, and tidal volume. Continuous positive airway pressure was associated with improved PaO2 , without concurrent hypercapnia. Volumetric capnography identified improved ventilation:perfusion (V/Q) matching and increased carbon dioxide elimination during ventilation, and spirometry identified decreased respiratory rate and increased tidal volume. Peak inspiratory pressure was moderately associated with PaO2 and lung volume. Improved pulmonary aeration was evident in CT images, and lung volume was increased, particularly during CPAP. Both CPAP and PSV improved lung mechanics and gas exchange in healthy foals with induced respiratory insufficiency.

A Rare Case of Pneumomediastinum Due to Prolonged Use of N95 Facemasks During the Covıd-19 Pandemic

This case and literature study aim to highlight a rare cause of pneumomediastinum in a health professional due to the long-term use of an N95 facemask during the pandemic. In our case, a twenty-eight-year-old female patient with mild intermittent asthma was presented to the emergency room with stinging pain in the anterior chest wall and parasternal areas. Laboratory tests and chest x-ray showed no significance, but pneumomediastinum was present on chest computed tomography. Pneumomediastinum is a rare complication in asthmatic patients. However, events that may cause alveolar and intrabronchial pressure increases can lead to pneumomediastinum. In conclusion, increased airway pressure due to prolonged use of N95 facemasks can lead to pneumomediastinum.

Continuous positive airway pressure (CPAP) for acute bronchiolitis in children.

Acute bronchiolitis is one of the most frequent causes of emergency department visits and hospitalisation in children up to three years of age. There is no specific treatment for bronchiolitis except for supportive treatment, which includes ensuring adequate hydration and oxygen supplementation. Continuous positive airway pressure (CPAP) aims to widen the lungs' peripheral airways, enabling deflation of overdistended lungs in bronchiolitis. Increased airway pressure also prevents the collapse of poorly supported peripheral small airways during expiration. Observational studies report that CPAP is beneficial for children with acute bronchiolitis. This is an update of a review first published in 2015 and updated in 2019. To assess the efficacy and safety of CPAP compared to no CPAP or sham CPAP in infants and children up to three years of age with acute bronchiolitis. We conducted searches of CENTRAL (2021, Issue 7), which includes the Cochrane Acute Respiratory Infections Group Specialised Register, MEDLINE (1946 to August 2021), Embase (1974 to August 2021), CINAHL (1981 to August 2021), and LILACS (1982 to August 2021) in August 2021. We also searched the US National Institutes of Health Ongoing Trials Register ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) for completed and ongoing trials on 26 October 2021. We considered randomised controlled trials (RCTs), quasi-RCTs, cross-over RCTs, and cluster-RCTs evaluating the effect of CPAP in children with acute bronchiolitis. Two review authors independently assessed study eligibility, extracted data using a structured pro forma, analysed data, and performed meta-analyses. We used the Cochrane risk of bias tool to assess risk of bias in the included studies. We created a summary of the findings table employing GRADEpro GDT software. MAIN RESULTS: We included three studies with a total of 122 children (62/60 in intervention/control arms) aged up to 12 months investigating nasal CPAP compared with supportive (or 'standard') therapy. We included one new trial (72 children) in the 2019 update that contributed data to the assessment of respiratory rate and the need for mechanical ventilation for this update. We did not identify any new trials for inclusion in the current update. The included studies were single-centre trials conducted in France, the UK, and India. Two studies were parallel-group RCTs, and one study was a cross-over RCT. The evidence provided by the included studies was of low certainty; we made an assessment of high risk of bias for blinding, incomplete outcome data, and selective reporting, and confidence intervals were wide. The effect of CPAP on the need for mechanical ventilation in children with acute bronchiolitis was uncertain due to risk of bias and imprecision around the effect estimate (risk difference -0.01, 95% confidence interval (CI) -0.09 to 0.08; 3 RCTs, 122 children; low certainty evidence). None of the trials measured time to recovery. Limited, low certainty evidence indicated that CPAP decreased respiratory rate (decreased respiratory rate is better) (mean difference (MD) -3.81, 95% CI -5.78 to -1.84; 2 RCTs, 91 children; low certainty evidence). Only one trial measured change in arterial oxygen saturation (increased oxygen saturation is better), and the results were imprecise (MD -1.70%, 95% CI -3.76 to 0.36; 1 RCT, 19 children; low certainty evidence). The effect of CPAP on change in arterial partial carbon dioxide pressure (pCO₂) (decrease in pCO₂ is better) was imprecise (MD -2.62 mmHg, 95% CI -5.29 to 0.05; 2 RCTs, 50 children;low certainty evidence). Duration of hospital stay was similar in both the CPAP and supportive care groups (MD 0.07 days, 95% CI -0.36 to 0.50; 2 RCTs, 50 children;low certainty evidence). Two studies did not report pneumothorax, but pneumothorax did not occur in one study. No studies reported occurrences of deaths. Several outcomes (change in partial oxygen pressure, hospital admission rate (from the emergency department to hospital), duration of emergency department stay, and need for intensive care unit admission) were not reported in the included studies. The use of CPAP did not reduce the need for mechanical ventilation in children with bronchiolitis, although the evidence was of low certainty. Limited, low certainty evidence suggests that breathing improved (a decreased respiratory rate) in children with bronchiolitis who received CPAP; this finding is unchanged from the 2015 review and 2019 update. Due to the limited available evidence, the effect of CPAP in children with acute bronchiolitis is uncertain for our other outcomes. Larger, adequately powered trials are needed to evaluate the effect of CPAP for children with acute bronchiolitis.

Sequential lateral positioning as a new lung recruitment maneuver: an exploratory study in early mechanically ventilated Covid-19 ARDS patients

BackgroundA sequential change in body position from supine-to-both lateral positions under constant ventilatory settings could be used as a postural recruitment maneuver in case of acute respiratory distress syndrome (ARDS), provided that sufficient positive end-expiratory pressure (PEEP) prevents derecruitment. This study aims to evaluate the feasibility and physiological effects of a sequential postural recruitment maneuver in early mechanically ventilated COVID-19 ARDS patients.MethodsA cohort of 15 patients receiving lung-protective mechanical ventilation in volume-controlled with PEEP based on recruitability were prospectively enrolled and evaluated in five sequentially applied positions for 30 min each: Supine-baseline; Lateral-1st side; 2nd Supine; Lateral-2nd side; Supine-final. PEEP level was selected using the recruitment-to-inflation ratio (R/I ratio) based on which patients received PEEP 12 cmH2O for R/I ratio ≤ 0.5 or PEEP 15 cmH2O for R/I ratio > 0.5. At the end of each period, we measured respiratory mechanics, arterial blood gases, lung ultrasound aeration, end-expiratory lung impedance (EELI), and regional distribution of ventilation and perfusion using electric impedance tomography (EIT).ResultsComparing supine baseline and final, respiratory compliance (29 ± 9 vs 32 ± 8 mL/cmH2O; p < 0.01) and PaO2/FIO2 ratio (138 ± 36 vs 164 ± 46 mmHg; p < 0.01) increased, while driving pressure (13 ± 2 vs 11 ± 2 cmH2O; p < 0.01) and lung ultrasound consolidation score decreased [5 (4–5) vs 2 (1–4); p < 0.01]. EELI decreased ventrally (218 ± 205 mL; p < 0.01) and increased dorsally (192 ± 475 mL; p = 0.02), while regional compliance increased in both ventral (11.5 ± 0.7 vs 12.9 ± 0.8 mL/cmH2O; p < 0.01) and dorsal regions (17.1 ± 1.8 vs 18.8 ± 1.8 mL/cmH2O; p < 0.01). Dorsal distribution of perfusion increased (64.8 ± 7.3% vs 66.3 ± 7.2%; p = 0.01).ConclusionsWithout increasing airway pressure, a sequential postural recruitment maneuver improves global and regional respiratory mechanics and gas exchange along with a redistribution of EELI from ventral to dorsal lung areas and less consolidation.Trial registration ClinicalTrials.gov, NCT04475068. Registered 17 July 2020, https://clinicaltrials.gov/ct2/show/NCT04475068

COMPARISON OF HEMODYNAMIC STATUS AND COMPLICATIONS BETWEEN TWO DIFFERENT DOSES OF INTRAMYOMETRIAL VASOPRESSIN DURING LAPAROSCOPIC MYOMECTOMY: A RETROSPECTIVE STUDY, THE LESSER THE BETTER

Objective: Our aim is comparison of hemodynamic status and complications between two different doses of intramyometrial vasopressin during laparoscopic myomectomy. Methods: We did a retrospective analysis of hemodynamic status and its anesthetic concerns in patients who received two different doses of intramyometrial vasopressin. Eighty patients undergoing laparoscopic myomectomy under general anesthesia were divided into two groups of 40 patients in each group. In Group A (n=40), 10 units of intramyometrial vasopressin in 200 ml of normal saline were given and, in Group B, 20 units of intramyometrial vasopressin in 200 ml of NS were given intraoperatively by surgeon. Results: 20 units intramyometrial vasopressin used dogmatically by surgeons drops blood loss but it is connected with cardiovascular impediments. Hence, 10 units of intramyometrial vasopressin as compared to 20 units which are used by some surgeons are associated with similar blood loss and lesser side effects such as bradycardia, pulmonary edema, hypotension, blood loss, and increased airway pressure. Conclusion: Hence, anesthesiologists and gynecologists must take the precautions to escape and minimize the frequency of impediments with intramyometrial vasopressin by selecting the appropriate dosage of vasopressin.

COMPARATIVE ANALYSIS OF PRESSURE CONTROLLED AND VOLUME CONTROLLED VENTILATION ON RESPIRATORY MECHANICS, HAEMODYNAMICS AND SYSTEMIC STRESS RESPONSE IN PATIENTS UNDERGOING SURGERY IN PRONE POSITION.

BACKGROUND: General Anaesthesia in prone position is related with increased airway pressure, decreased pulmonary and thoracic compliance. AIM: Comparision of pressure controlled and volume controlled ventilation in patients undergoing lumbar spine surgery in prone position.METHODS: After ethics committee approval &amp; written informed consent, a comparative randomized interventional study was conducted from July-December 2017. Randomization was done using random number tables. Patients of either sex, ASA grade I&amp;II, age 25-55 yrs were included while those with severe pulmonary ,cardiovascular, endocrine disease &amp; BMI&gt; 30kg/m2 were excluded. Patients were randomly assigned to VCV group (n = 30), or PCV group (n = 30). Haemodynamic (HR,SBP,DBP,MAP), Respiratory (P-Peak,P-mean,C-dyn) variables,blood glucose,S.cortisol were measured and ABG analysis was done 10 minutes after intubation (T1), 30 minutes after prone positioning(T2) and 60 minuts after extubation(T3). RESULTS: Demographic parameters , perioperative hemodynamic values were comparable with no significant statistical difference.The P-Peak levels were lower and dynamic compliance was higher in PCV group during both T1 and T2 with p value of less than 0.05 Postoperative PaO2 level was significantly higher in Group PCV compared with Group VCV.The difference between post operative and preoperative serum cortisol and blood glucose levels was significantly less in patients ventilated with PCV mode.CONCLUSION: According to our study,PCV mode is associated with lower P-peak levels during prone position, better oxygenation postoperatively and lesser systemic stress response.We concluded that PCV mode might be more appropriate in prone position surgeries.

Clinical reasoning in anaphylactic shock: addressing the challenges faced by anaesthesiologists in real time: A clinical review and management algorithms.

Acute hypersensitivity reactions to drugs occur infrequently during anaesthesia and the peri-operative period. When clinical presentation includes the classical triad, erythema, cardiovascular abnormalities and increased airway pressure, the diagnosis is evident and the challenge is to prescribe a therapeutic regimen according to guidelines and to manage refractory signs in a timely manner. In many situations, however, the initial clinical signs are isolated, such as increased airway pressure or arterial hypotension. Rendering a differential diagnosis with causes and mechanisms other than acute hypersensitivity reactions (AHRs) is difficult, delaying treatment with possible worsening of the clinical signs, and even death, in previously healthy individuals. In these difficult diagnostic situations, clinical reasoning is mandatory, and guidelines do not explicitly explain the elements on which clinical reasoning can be built. In this article, based on clinical evidence whenever available, experimental data and pathophysiology, we propose algorithms that have been evaluated by experts. The goal of these algorithms is to provide explicit elements on which the differential diagnosis of AHRs can be made, accelerating the implementation of adequate therapy.

Sustained Inflation Reduces Pulmonary Blood Flow during Resuscitation with an Intact Cord.

The optimal timing of cord clamping in asphyxia is not known. Our aims were to determine the effect of ventilation (sustained inflation–SI vs. positive pressure ventilation–V) with early (ECC) or delayed cord clamping (DCC) in asphyxiated near-term lambs. We hypothesized that SI with DCC improves gas exchange and hemodynamics in near-term lambs with asphyxial bradycardia. A total of 28 lambs were asphyxiated to a mean blood pressure of 22 mmHg. Lambs were randomized based on the timing of cord clamping (ECC—immediate, DCC—60 s) and mode of initial ventilation into five groups: ECC + V, ECC + SI, DCC, DCC + V and DCC + SI. The magnitude of placental transfusion was assessed using biotinylated RBC. Though an asphyxial bradycardia model, 2–3 lambs in each group were arrested. There was no difference in primary outcomes, the time to reach baseline carotid blood flow (CBF), HR ≥ 100 bpm or MBP ≥ 40 mmHg. SI reduced pulmonary (PBF) and umbilical venous (UV) blood flow without affecting CBF or umbilical arterial blood flow. A significant reduction in PBF with SI persisted for a few minutes after birth. In our model of perinatal asphyxia, an initial SI breath increased airway pressure, and reduced PBF and UV return with an intact cord. Further clinical studies evaluating the timing of cord clamping and ventilation strategy in asphyxiated infants are warranted.

AB222. SOH21AS151. Severe intra-operative anaphylactic reaction to co-amoxiclav despite having a previous uneventful exposure

: Co-amoxiclav is used as a routine prophylactic antibiotic in surgical procedures. We present a case of a 45-year-old lady who was scheduled for elective repair of incisional hernia. Her past medical history was controlled hypertension with no previous drug or food allergy. On reviewing her past anaesthetic sheet, she was tolerant to the antibiotic with no reaction. In addition, on further questioning, she did mention receiving Co-amoxiclav several times orally without any complication. On the day of surgery, after induction of anaesthesia, the patient was given 1.2 g of Co-amoxiclav as per hospital protocol. Within 10 minutes, the patient developed severe bronchospasm with increased airway pressure and severe hypotension indicating anaphylactic shock. The patient was resuscitated and recovered successfully. The surgery was cancelled and the patient was provided a bed in the high dependency unit (HDU) for overnight monitoring and further investigations. Every theatre or ward that admit antibiotic should have a clear protocol for management of anaphylactic shock. Availability of adrenaline and timely delivery of the drug plays a core role in successful management of anaphylaxis.

Collapsibility of caval vessels and right ventricular afterload: decoupling of stroke volume variation from preload during mechanical ventilation.

Collapsibility of caval vessels and stroke volume and pulse pressure variations (SVV, PPV) are used as indicators of volume responsiveness. Their behavior under increasing airway pressures and changing right ventricular afterload is incompletely understood. If the phenomena of SVV and PPV augmentation are manifestations of decreasing preload, they should be accompanied by decreasing transmural right atrial pressures. Eight healthy pigs equipped with ultrasonic flow probes on the pulmonary artery were exposed to positive end-expiratory pressure of 5 and 10 cmH2O and three volume states (Euvolemia, defined as SVV < 10%, Bleeding, and Retransfusion). SVV and PPV were calculated for the right and PPV for the left side of the circulation at increasing inspiratory airway pressures (15, 20, and 25 cmH2O). Right ventricular afterload was assessed by surrogate flow profile parameters. Transmural pressures in the right atrium and the inferior and superior caval vessels (IVC and SVC) were determined. Increasing airway pressure led to increases in ultrasonic surrogate parameters of right ventricular afterload, increasing transmural pressures in the right atrium and SVC, and a drop in transmural IVC pressure. SVV and PPV increased with increasing airway pressure, despite the increase in right atrial transmural pressure. Right ventricular stroke volume variation correlated with indicators of right ventricular afterload. This behavior was observed in both PEEP levels and all volume states. Stroke volume variation may reflect changes in right ventricular afterload rather than changes in preload.NEW & NOTEWORTHY Stroke volume variation and pulse pressure variation are used as indicators of preload or volume responsiveness of the heart. Our study shows that these variations are influenced by changes in right ventricular afterload and may therefore reflect right ventricular failure rather than pure volume responsiveness. A zone of collapse detaches the superior vena cava and its diameter variation from the right atrium.

Malignant hyperthermia: a case report with good outcome.

Malignant hyperthermia: a case report with good outcome.

Contralateral tension pneumothorax during video-assisted thoracic surgery for lung cancer in a patient with obesity and rib fractures: a case report and review of the literature

BackgroundIntraoperative contralateral pneumothorax during one-lung ventilation is a rare but life-threatening complication. Although the exact incidence is unknown, only 14 cases with this complication have been reported until now.Case presentationA 67-year-old Japanese man with a weight of 80 kg, height of 162.2 cm, and body mass index of 30.4 kg/m2 underwent three-port video-assisted thoracic surgery for lung cancer with one-lung ventilation. He had suffered from traumatic right rib fractures 6 weeks before the referral. Fifteen minutes before the end of the surgery, the systolic blood pressure suddenly dropped to about 50 mmHg, which was immediately recovered by intravenous injection of phenylephrine. This episode occurred during chest closure after the completion of the left upper lobectomy, and one-lung ventilation was soon switched to two-lung ventilation. Contralateral tension pneumothorax was noted by the postoperative chest x-ray. As the patient was complicated with obesity and a past history of rib fractures, increased airway pressure during one-lung ventilation related to obesity together with the persistent compression of the visceral pleura by the fractured ends of the ribs was considered to be the factors responsible for this critical complication.ConclusionsPatient backgrounds such as obesity and past history of rib fractures should be noted carefully as risk factors for intraoperative contralateral pneumothorax during one-lung ventilation. We present the clinical course and discuss the mechanism of development of this potentially life-threatening complication in the present case with a review of the literature.

The Perioperative and Anesthetic Adverse Events in Thailand (PAAd Thai) Study of Endobronchial Intubation: An Analysis of 2,000 Incident Reports

Background: The Royal College of Anesthesiologists of Thailand hosted a multicentered project, namely the Perioperative and Anesthetic Adverse Events in Thailand (PAAd Thai) Study. Objective: The aims of the present study were to investigate incidences, contributing factors and suggested preventive strategies of anesthesia-related complications particularly the endobronchial intubation (EBI). Materials and Methods: The PAAd Thai study was a collaborative incident report among 22 hospitals across Thailand. After approval by the Institutional Ethical Committee, the structured incident report together with open ended data record form of anesthesia-related complications such as cardiac arrest, death within 24 hours, and respiratory complications including EBI were requested to be sent to the data management center together with monthly statistics of anesthesia service in each hospital for 12 months (between January 2015 and December 2015) on an anonymous and voluntary basis. The EBI reports were reviewed by three anesthesiologists. Any discretion was discussed to achieve a consensus. Descriptive statistics were used. Results: Among the first 2,000 incident reports, there were 23 EBIs, at the rate of 1.06:10,000 (95% CI 0.62 to 1.49) or 1.15% of all reports. Two-thirds of the incidents occurred in patients with age less than 5 years old and more than 60 years old, and in elective cases. The common sites of surgery were trunk, head and neck, and laparoscopic procedures. EBIs were diagnosed by pulse oximeter (13 cases, 54.0%), increased airway pressure (four cases, 17.2%) and clinical monitoring (four cases 17.2%). Common phases of detection were pre-induction (one case, 4.3%), induction (nine cases, 39.2%), maintenance (12 cases, 52.2%), and emergence (one case, 4.3%). Contributing factors were lack of knowledge, inexperience, and haste, while factors minimizing the incidents were having experience and vigilance. Suggested preventive strategies were additional training, including simulation, practice guidelines, improvement of supervision, and communication. Conclusion: The authors have found that EBI was uncommon, but it is one of the serious anesthesia-related adverse events. It can happen anytime during the entire course of anesthesia. Under these circumstances, careful monitoring and vigilance of the anesthesiologists is essential. Keywords: Anesthesia, Complication, Endobronchial intubation, Intubation, Hypoxia