Fractional Inspired Oxygen Concentration Research Articles

Use of THRIVE for Apneic Oxygenation in Transoral Laser Microlaryngeal Surgery: A Scoping Review.

Trans-nasal humidified rapid insufflation ventilatory exchange (THRIVE) has demonstrated utility in extending the apneic window in the perioperative setting. Its benefits in facilitating tubeless anesthesia are recognized during elective laryngotracheal surgeries. The use of THRIVE and administering higher fractional inspired oxygen concentrations in laser laryngeal surgery (LLS) remains controversial due to the theoretical risk of airway fires. A scoping review of the literature describing institutional experiences with THRIVE during LLS was conducted. A systematic scoping review of the literature was performed including PubMed, Medline, Embase, Scopus, JBI EBP Database, and Cochrane Library from inception to April 2023. From the 472 articles identified in our review, nine articles were included representing 271 cases. THRIVE was used for preoxygenation and to maintain apneic oxygenation during LLS. Different institutional practices related to THRIVE parameters and intraoperative modifications during lasing were described in the literature, including cessation of THRIVE, reduction of FiO2 to 30%, and continuous 100% FiO2 oxygenation. One study described a brief ignition of the coating of a KTP laser fiber without injury to the patient. No adverse patient outcomes have been documented in the literature with THRIVE during LLS. THRIVE is a safe and effective form of tubeless anesthesia and apneic oxygenation during LLS, with no adverse patient safety events reported in the literature. Key determinants to maintain safety include optimal patient and team selection, effective surgeon-anesthetist cooperation, and institutional protocols that govern intraoperative practice. Laryngoscope, 2024.

Effects of gestational intermittent hypoxia on the autoresuscitation response following anoxia-induced apneas in neonatal mice

Introduction: Sudden infant death syndrome (SIDS) is the leading cause of death in infants from one month to one year of age. Smoking is a significant risk factor in SIDS, and smoking probably causes intermittent hypoxia in the fetus. Therefore, we modeled the effects of intermittent hypoxia during gestation in mice to determine if gestational intermittent hypoxia would adversely affect the capacity of neonatal mice to autoresuscitate effectively after exposure to anoxic stimuli. A degraded capacity to autoresuscitate could explain, in part, why infants born to mothers who smoke have an increased risk of dying from of SIDS. The primary objective of this study was to investigate the effects of intermittent gestational hypoxia on the autoresuscitation responses to anoxia-induced apneas in neonatal mice. Our hypothesis was that pups born to intermittently hypoxic dams would struggle more to recover from anoxic apneas — would have impaired cardiorespiratory responses to anoxic stress compared to the control mice born to dams exposed to room air during gestation. Methods: We studied C57Bl/6 dams who previously had one litter to prove their capability to breed and rear pups. Dams were placed in either an hypoxic or room air chamber at approximately embryonic day 5 (E5; fifth day of pregnancy). The fractional inspired oxygen concentration (FIO2) was reduced to 11% for 10 minutes, three times per hour, with 10 minute periods of 21% oxygen between them. Each hour of intermittent hypoxia was followed by an hour breathing 21% FiO2. The room air control chamber was maintained at a constant FIO2 of 21% with inflows of compressed air that mimicked the noise and flow of nitrogen in the hypoxic chamber. The dams spent the entirety of their pregnancies in the environmental chambers. Once the pups were delivered, the cages were placed in room air, housing environments. The pups were allowed to stay with their mothers until approximately post-natal day 8 (P8). On P8, each pup was fitted into a head out plethysmograph to measure respiratory flow using a pneumotachograph. We recorded respiratory activity, ECG activity, and body movements (using a piezo sensitive film). The pups were maintained at ~34 degrees C in the pneumotachographic chamber. We measured the highest respiratory rate, highest heart rate, longest apnea, gasp latency, mean heart rate recovery, and mean respiratory rate recovery. Results: The mean heart rate recovery and mean longest apnea (in seconds) doubled in the mice exposed to gestational intermittent hypoxia compared to pups born to dams exposed to room air during gestation. The mean heart rate recovery and mean longest apnea in gestationally hypoxic pups was 41.0 +/- 13.7 seconds and 22.05 +/- 12.0 seconds, respectively. The mean heart rate recovery and mean longest apnea in normal, room air-exposed pups was 22.4 +/- 11.1 seconds and 10.3 +/- 7.0 seconds, respectively. The longest apnea in gestational intermittent hypoxic pups was significantly longer than in control pups (53.0 +/- 13.7 seconds and 19.1 +/- 15.0 seconds). Pups exposed to gestational intermittent hypoxia also had increased mean respiratory rate recovery times and gasp latency times (start of apnea until the first gasp). The average body weight of hypoxic pups was 4.3 grams while the average body weight for the normal pups was 4.9 grams. Conclusion: Gestational intermittent hypoxia was associated with delayed and prolonged the autoresuscitation responses in neonatal mice following acute anoxic exposure. We hypothesize that this is due to changes in the brain’s serotonin system. We are investigating how intrauterine hypoxia may decrease serotonin and serotonergic signaling pathways as changes in serotonergic function may degrade the capacity of mice to autoresuscitate following anoxic gas exposure. NIH/NICHD. HD100823 and NIH/NICHD. HD 107060. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

A Good Prognosis of Patients with Acute Pancreatitis Combined with Pulmonary Embolism: Early Identification and Intervention.

Pulmonary embolism (PE) is a relatively rare vascular complication of acute pancreatitis (AP), and its mortality rate is high. To our knowledge, relevant literature reports still need to be summarized. In this study, we analyzed the clinical characteristics, treatment, and prognosis of five patients with AP complicated by PE and summarized and reviewed the relevant literature. Clinical data of patients with AP complicated by PE treated in Taizhou Hospital of Zhejiang Province between January 2017 and September 2022 were retrospectively collected. Combined with the relevant literature, the clinical characteristics, treatment, and prognoses of patients with AP combined with PE were analyzed and summarized. Five patients were eventually enrolled in this study. Among the five patients with AP complicated by PE, all (100%) had symptoms of malaise, primarily chest tightness, shortness of breath, and dyspnea. All patients (100%) had varied degrees of elevated D-dimer levels and a significant decrease in the pressure of partial oxygen (PO2) and pressure of arterial oxygen to fractional inspired oxygen concentration ratio (PaO2/FiO2). Computed tomographic angiography (CTA) or pulmonary ventilation/perfusion imaging revealed a pulmonary artery filling defect in these patients. One patient (20%) had left calf muscular venous thrombosis before the occurrence of PE. Four patients (80%) were treated with lowmolecular- weight heparin (LMWH), and one patient (20%) was treated with rivaroxaban during hospitalization; all continued oral anticoagulant therapy after discharge. All patients (100%) were cured and discharged. No patients showed recurrence of AP or PE. PE is a rare but life-threatening complication of AP. However, once diagnosed, early treatment with anticoagulation or radiological interventional procedures is effective, and the prognosis is good. Core Tips: Pulmonary embolism (PE) is a rare but life-threatening complication of acute pancreatitis (AP). Its early diagnosis and timely anticoagulation or radiological intervention can reduce mortality. However, only nine cases have been reported in the English literature thus far, and they are all case reports. Our study is the first systematic analysis of patients with AP combined with PE with a review of the relevant literature. Our patients and those reported in the literature were discharged with good prognoses under treatment such as anticoagulation and vascular intervention. These cases remind clinicians that, in patients with AP, especially those with risk factors for venous thrombosis, it is necessary to monitor the D-dimer level dynamically. Clinicians should pay attention to AP patients' symptoms and related examinations to reduce the chance of a missed diagnosis or misdiagnosis of PE.

Association of Conventional Ultrafiltration on Postoperative Pulmonary Complications

BackgroundPostoperative pulmonary complications increase mortality after cardiac surgery. Conventional ultrafiltration may reduce pulmonary complications by removing mediators of bypass-induced inflammation and countering hemodilution. We tested the primary hypothesis that conventional ultrafiltration reduces postoperative pulmonary complications, and secondarily, improves early pulmonary function assessed by the ratio of PaO2 to fractional inspired oxygen concentration. MethodsThis retrospective analysis compared the incidence of postoperative pulmonary complications in adult patients who underwent cardiac surgery, with and without the use of conventional ultrafiltration, by using logistic regression with adjustment for confounding variables. The primary outcome was a composite of reintubation, prolonged ventilation, pneumonia, or pleural effusion. Secondarily, we examined early postoperative lung function using a quantile regression model. We also explored whether red blood cell transfusion differed between groups. ResultsOf 8026 patients, 1043 (13%) received conventional ultrafiltration. After adjustment for confounding variables, the incidence of the composite primary outcome was higher in the conventional ultrafiltration group (12.1% vs 9.9%; P = .03), with an estimated odds ratio of 1.25 (95% CI, 1.02-1.53; P = .03). The median (quantiles) PaO2–to–fractional inspired oxygen concentration ratio was 373 (303-433) vs 368 (303-428), with the estimated adjusted difference in medians of 5 (95% CI, −5.9 to 16; P = .37). The estimated odds ratio of intraoperative transfusion was 1.38 (95% CI, 1.19-1.60; P < .0001) and for postoperative transfusion was 1.30 (95% CI, 1.14-1.49; P = .0001). ConclusionsUse of conventional ultrafiltration was not associated with a reduction in the composite of postoperative pulmonary complications or improved early pulmonary function. We found no evidence of benefit from use of conventional ultrafiltration during cardiac surgery.

Evaluating the use of the respiratory-rate oxygenation index as a predictor of high-flow nasal cannula oxygen failure in COVID-19.

It can be challenging for clinicians to predict which patients with respiratory failure secondary to coronavirus disease 2019 (COVID-19) will fail on high-flow nasal cannula (HFNC) oxygen and require escalation of therapy. This study set out to evaluate the association between the respiratory rate-oxygenation index (ROX) and HFNC failure in such patients and to assess whether ROX trajectory correlates with treatment failure. This was a single-centre, retrospective, observational study of patients with COVID-19 requiring HFNC, conducted over a 3-month period. ROX was calculated as "pulse-oximetry oxygen saturation (SpO2) over the fractional inspired oxygen concentration (FiO2)/respiratory rate" for each patient at 2, 4, and 12 hours from starting HFNC. HFNC failure was defined as escalation to continuous positive airway pressure ventilation or invasive mechanical ventilation (IMV). Time-to-event analyses were performed to account for the longitudinal data set and time-dependent variables. We included 146 patients. Ninety-three (63.7%) experienced HFNC failure, with 53 (36.3%) requiring IMV. Higher ROX values were associated with a lower subhazard of HFNC failure on time-to-HFNC failure analysis (subhazard ratio, 0.29; 95% confidence interval [CI], 0.18-0.46; P<0.001). This remained true after controlling for informative censoring. Median ROX values changed differentially over time, increasing in the HFNC success group (0.06 per hour; 95% CI, 0.05-0.08; P<0.001) but not in the HFNC failure group (0.004 per hour; 95% CI, -0.05 to 0.08; P=0.890). A higher ROX is associated with a lower risk of HFNC failure. Monitoring ROX trajectory over time may help identify patients at risk of treatment failure. This has potential clinical applications; however, future prospective studies are required.

Weaning Outcomes and 28-day Mortality after Tracheostomy in COVID-19 Patients in Central India: A Retrospective Observational Cohort Study.

BackgroundTracheostomy is integral in long-term intensive care of coronavirus disease-2019 (COVID-19) patients. There is a paucity of studies on weaning outcomes and mortality after tracheostomy in COVID-19 in Indian scenario.Materials and methodsWe conducted a retrospective, single-center, observational study of severe COVID-19 patients who underwent elective tracheostomy (n = 65) during critical care in a tertiary care institute in Central India from May 1, 2020, to April 30, 2021. Data were collected from Medical records, ICU charts, and follow-up visits by patient. A primary objective was to study the clinical characteristics, tracheostomy complications, weaning outcomes, and mortality at 28 and 60 days of ICU admission. We categorized the cohort into two groups (deceased and survivor) and studied association of clinical parameters with 28-day mortality. Cox Proportional regression analysis was applied to calculate the hazard ratio among the predictors of mortality with p value <0.05 as significant.ResultsElective tracheostomy was done in 69 of 436 (15.8%) patients on invasive mechanical ventilation, of which 65 were included. Tracheostomy was percutaneous in 45/65 (69%) and surgical in 20/65 (31%) with timing from intubation as early in 41/65 and late in 24/65 with most common indication as weaning failure followed by anticipated prolonged ventilation. Tracheostomy complications were present in 29/65 (45%) patients with no difference in complication rates between timing and type of tracheostomy. Downsizing, decannulation, and weaning were successful in 22%, 32 (49%), and 35/65 (54%) patients after tracheostomy. The 28-day mortality was 30/65 (46%). The fractional inspired oxygen concentration (FiO2) requirement in survivors was lower (0.4–0.6, p = 0.015) with a higher PaO2/FiO2 ratio (118–200, p = 0.033). Early tracheostomy within 7 days of intubation was not associated with weaning or survival benefit.ConclusionsWe suggest that tracheostomy should be delayed to after 7 days of intubation, especially till FiO2 reduces to 0.5 with improvement in PaO2/FiO2 for better outcomes and avoiding a wasted procedure (CTRI/2021/07/034768).Study HighlightsTracheostomy is integral in care of COVID-19 patients needing prolonged ventilation. There is no difference in complications in early/late or percutaneous dilatational/surgical technique. We observed successful weaning post-tracheostomy in 54% patients. Mortality at 28 days was 46%. Early tracheostomy within 7 days of intubation did not improve weaning or survival.How to cite this articleKarna ST, Trivedi S, Singh P, Khurana A, Gouroumourty R, Dodda B, et al. Weaning Outcomes and 28-day Mortality after Tracheostomy in COVID-19 Patients in Central India: A Retrospective Observational Cohort Study. Indian J Crit Care Med 2022;26(1):85–93.

Decreasing Continuous Positive Airway Pressure Failure in Preterm Infants.

Many preterm infants stabilized on continuous positive airway pressure (CPAP) at birth require mechanical ventilation (MV) during the first 72 hours of life, which is defined as CPAP failure. Our objective was to decrease CPAP failure in infants ≤29 weeks' gestational age (GA). A quality improvement bundle named OPTISURF was implemented for infants ≤29 weeks' GA admitted on CPAP, consisting of stepwise escalation of CPAP and less invasive surfactant administration guided by fractional inspired oxygen concentration ≥0.3. The CPAP failure rate was tracked by using control charts. We compared practice and outcomes of a pre-OPTISURF cohort (January 2017 to September 2018) to a post-OPTISURF cohort (October 2018 to December 2019). Of the 216 infants ≤29 weeks' GA admitted to NICU on CPAP, 125 infants belonged to the pre-OPTISURF cohort (OSC) and 91 to the post-OSC. Compared with the pre-OSC, a higher proportion of infants in the post-OSC received CPAP 7 cm H2O within 4 hours of life (7% vs 32%; P < .01). The post-OSC also had lower rates of CPAP failure (54% vs 11%; P < .01), pneumothoraces (8% vs 1%; P < .03), need for MV (58% vs 31%; P < .01), and patent ductus arteriosus treatment (21% vs 9%; P = .02). Additionally, in a subgroup analysis, CPAP failure was lower in the post-OSC among infants 23 to 26 weeks (79% vs 27%; P < .01) and 27 to 29 weeks' GA (46% vs 3%; P < .01). Implementation of a quality improvement bundle including CPAP optimization and less invasive surfactant administration decreased CPAP failure and need for MV in preterm infants.

Tofacitinib as a novel therapy in COVID-19 acute respiratory distress syndrome.

Tofacitinib as a novel therapy in COVID-19 acute respiratory distress syndrome.

Bubble CPAP splitting: innovative strategy in resource-limited settings

BackgroundNon-invasive respiratory support for neonates using bubble continuous positive airway pressure (bCPAP) delivery systems is now widespread owing to its safety, cost effectiveness and easy applicability. Many innovative solutions have...

Ventilatory management of patients on ECMO.

Extracorporeal membrane oxygenation (ECMO) is the final treatment offered to patients of acute respiratory distress syndrome (ARDS). The survival (to discharge) of patients on veno-venous ECMO is approximately 59% with an average duration of 8 days. The ventilatory management of lungs during the ECMO may have an impact on mortality. An ideal ventilation modality should promote recovery, prevent further damage to the alveoli, and enable weaning from mechanical ventilation. This article reviews the concept of “baby lung” in ARDS and the current evidence for the use of lung protective ventilation, prevention of ventilator-induced lung injury, recommended modes of mechanical ventilation, ideal ventilatory parameters (tidal volume, positive end expiratory pressure, plateau pressure, respiratory rate, fractional inspired oxygen concentration), and use of adjuncts (prone positioning, neuromuscular blocking agents) during the ECMO course.

The influence of delayed sample processing time on PO2 values in critically ill patients with sepsis-induced leucocytosis

Background: The extent of error, from collection to processing, when measuring PO2, PCO2 and pH in arterial blood samples drawn from critically ill patients with sepsis and leucocytosis, is unknown. Methods: Twenty-nine patients with sepsis and a leucocyte count &gt; 12 000/mm3, who had routine arterial blood analysis were included in the study. Blood was drawn into two 1 ml heparinised glass syringes. One syringe was cooled on ice and tested at 60 minutes. The other syringe was used for analysis at 0, 10, 30 and 60 minutes. Differences in measurements, from the Time-0 results, were described. For PO2, linear mixed models estimated the impact of time to processing, controlling for the potentially confounding and moderating effects of Time-0 leucocyte count and fractional inspired oxygen concentration respectively. Results: PO2 exhibited the most pronounced changes over time at ambient temperature: The mean (SD) relative differences at 10, 30 and 60 minutes were -4.72 (8.82), -13.66 (10.25), and -25.12 (15.55)% respectively; and mean (SD) absolute differences -0.88 (1.49), -2.37 (1.89) and -4.32 (3.06) kPa. For pH, at 60 minutes, the mean (SD) relative and absolute differences were -0.27 (0.45)% and -0.02 (0.03) respectively; for PCO2, 6.16 (7.80)% and 0.25 (0.35) kPa. The median differences for the on-ice 60-minute sample for pH and PCO2 were 0.019 and -0.12 (both P &lt; 0.001), and for PO2 0.100 (P: 0.216). The model estimated that average PO2 decreased by 5% per 10 minute delay in processing (95% CI for effect: 0.94 to 0.96; P &lt; 0.001) at the average leucocyte count, with more rapid declines at higher counts, though with substantial inter-patient variation. Conclusion: Delayed blood gas analysis in samples stored at ambient temperature results in a statistically and clinically significant progressive decrease in arterial PO2, which may alter clinical decision-making in septic patients.

The influence of delayed sample processing time on PO2 values in critically ill patients with sepsis-induced leucocytosis

Background: The extent of error, from collection to processing, when measuring PO2, PCO2 and pH in arterial blood samples drawn from critically ill patients with sepsis and leucocytosis, is unknown. Methods: Twenty-nine patients with sepsis and a leucocyte count &gt; 12 000/mm3, who had routine arterial blood analysis were included in the study. Blood was drawn into two 1 ml heparinised glass syringes. One syringe was cooled on ice and tested at 60 minutes. The other syringe was used for analysis at 0, 10, 30 and 60 minutes. Differences in measurements, from the Time-0 results, were described. For PO2, linear mixed models estimated the impact of time to processing, controlling for the potentially confounding and moderating effects of Time-0 leucocyte count and fractional inspired oxygen concentration respectively. Results: PO2 exhibited the most pronounced changes over time at ambient temperature: The mean (SD) relative differences at 10, 30 and 60 minutes were -4.72 (8.82), -13.66 (10.25), and -25.12 (15.55)% respectively; and mean (SD) absolute differences -0.88 (1.49), -2.37 (1.89) and -4.32 (3.06) kPa. For pH, at 60 minutes, the mean (SD) relative and absolute differences were -0.27 (0.45)% and -0.02 (0.03) respectively; for PCO2, 6.16 (7.80)% and 0.25 (0.35) kPa. The median differences for the on-ice 60-minute sample for pH and PCO2 were 0.019 and -0.12 (both P &lt; 0.001), and for PO2 0.100 (P: 0.216). The model estimated that average PO2 decreased by 5% per 10 minute delay in processing (95% CI for effect: 0.94 to 0.96; P &lt; 0.001) at the average leucocyte count, with more rapid declines at higher counts, though with substantial inter-patient variation. Conclusion: Delayed blood gas analysis in samples stored at ambient temperature results in a statistically and clinically significant progressive decrease in arterial PO2, which may alter clinical decision-making in septic patients.

The effect of fractional inspired oxygen concentration on early warning score performance: A database analysis

ObjectivesTo calculate fractional inspired oxygen concentration (FiO2) thresholds in ward patients and add these to the National Early Warning Score (NEWS). To evaluate the performance of NEWS-FiO2 against NEWS when predicting in-hospital death and unplanned intensive care unit (ICU) admission. MethodsA multi-centre, retrospective, observational cohort study was carried out in five hospitals from two UK NHS Trusts. Adult admissions with at least one complete set of vital sign observations recorded electronically were eligible. The primary outcome measure was an ‘adverse event’ which comprised either in-hospital death or unplanned ICU admission. Discrimination was assessed using the Area Under the Receiver Operating Characteristic curve (AUROC). ResultsA cohort of 83,304 patients from a total of 271,363 adult admissions were prescribed oxygen. In this cohort, NEWS-FiO2 (AUROC 0.823, 95% CI 0.819–0.824) outperformed NEWS (AUORC 0.811, 95% CI 0.809–0.814) when predicting in-hospital death or unplanned ICU admission within 24 h of a complete set of vital sign observations. ConclusionsNEWS-FiO2 generates a performance gain over NEWS when studied in ward patients requiring oxygen. This warrants further study, particularly in patients with respiratory disorders.

Protocol for a feasibility randomised controlled trial of targeted oxygen therapy in mechanically ventilated critically ill patients

IntroductionOxygen is the most commonly administered drug to mechanically ventilated critically ill adults, yet little is known about the optimum oxygen saturation (SpO2) target for these patients; the current standard...

Variation of Risk Factors for Cause-Specific Reintubation: A Preliminary Study.

Unexpected reintubation may occur, even if the risk factors are considered and a spontaneous breathing trial is successful. Reintubation is thought to be caused by various factors. Several studies have investigated the risk factors of reintubation, but most did not classify reintubation by cause. We retrospectively classified patients undergoing reintubation at intensive care unit by cause (respiratory insufficiency vs. nonrespiratory insufficiency) to examine the cause-specific risk factors of reintubation. A total of 262 patients were included; reintubation within 48 hours after extubation was performed in 12 patients (reintubation rate, 4.5%). After classification by cause of reintubation, the pressure of arterial oxygen to fractional inspired oxygen concentration (P/F) ratio exhibited a significant association with reintubation only in the respiratory insufficiency group (odds ratio (OR) 0.989, 95% confidence interval (CI) 0.980 to 0.999, p=0.036, and OR 0.989, 95% CI 0.979 to 0.999, p=0.026, in the univariate and multivariate analyses, respectively). In the propensity score analysis, a P/F ratio ≤ 200 may be a risk factor for reintubation in the respiratory insufficiency group (OR 7.811, 95% CI 1.345 to 45.367, p=0.022). In the nonrespiratory insufficiency group, intubation duration was significantly related to reintubation (OR 1.165, 95% CI 1.012 to 1.342, p=0.033, and OR 1.163, 95% CI 1.004 to 1.348, p=0.044, in the univariate and multivariate analyses, respectively). In conclusion, a low P/F ratio at extubation may be a risk factor for reintubation due to respiratory insufficiency. In the nonrespiratory insufficiency group, intubation duration may be significantly related to reintubation. The risk factors for reintubation may differ by the cause of reintubation. Further large-scale randomized controlled trials are required.

Intraoperative oxygenation in adult patients undergoing surgery (iOPS): a retrospective observational study across 29 UK hospitals

BackgroundConsiderable controversy remains about how much oxygen patients should receive during surgery. The 2016 World Health Organization (WHO) guidelines recommend that intubated patients receive a fractional inspired oxygen concentration (FIO2) of 0.8 throughout abdominal surgery to reduce the risk of surgical site infection. However, this recommendation has been widely criticised by anaesthetists and evidence from other clinical contexts has suggested that giving a high concentration of oxygen might worsen patient outcomes. This retrospective multi-centre observational study aimed to ascertain intraoperative oxygen administration practice by anaesthetists across parts of the UK.MethodsPatients undergoing general anaesthesia with an arterial catheter in situ across hospitals affiliated with two anaesthetic trainee audit networks (PLAN, SPARC) were eligible for inclusion unless undergoing cardiopulmonary bypass. Demographic and intraoperative oxygenation data, haemoglobin saturation and positive end-expiratory pressure were retrieved from anaesthetic charts and arterial blood gases (ABGs) over five consecutive weekdays in April and May 2017.ResultsThree hundred seventy-eight patients from 29 hospitals were included. Median age was 66 years, 205 (54.2%) were male and median ASA grade was 3. One hundred eight (28.6%) were emergency cases. An anticipated difficult airway or raised BMI was documented preoperatively in 31 (8.2%) and 45 (11.9%) respectively. Respiratory or cardiac comorbidity was documented in 103 (27%) and 83 (22%) respectively. SpO2 < 96% was documented in 83 (22%) patients, with 7 (1.9%) patients desaturating < 88% at any point intraoperatively. The intraoperative FIO2 ranged from 0.25 to 1.0, and median PaO2/FIO2 ratios for the first four arterial blood gases taken in each case were 24.6/0.5, 23.4/0.49, 25.7/0.46 and 25.4/0.47 respectively.ConclusionsIntraoperative oxygenation currently varies widely. An intraoperative FIO2 of 0.5 currently represents standard intraoperative practice in the UK, with surgical patients often experiencing moderate levels of hyperoxaemia. This differs from both WHO’s recommendation of using an FIO2 of 0.8 intraoperatively, and also, the value most previous interventional oxygen therapy trials have used to represent standard care (typically FIO2 = 0.3). These findings should be used to aid the design of future intraoperative oxygen studies.

Abstract PCCLB-15: ANAESTHESIA CONSENSUS ON CLINICAL PARAMETERS FOR THE TIMING OF SURGICAL REPAIR IN CONGNEITAL DIAPHRAGMATIC HERNIA

Aims & Objectives: Anaesthesia for the surgical repair of congenital diaphragmatic hernia (CDH) is challenging due to the presence of pulmonary hypertension, secondary reduced cardiac function and reduced gas exchange because of pulmonary hypoplasia. Surgery may be delayed if the patient’s clinical condition is not optimised or all appropriate investigations have not been performed. To reduce deferrals of CDH repair surgery we set out to develop a consensus document that standardises patient optimisation and preparation preoperatively. Methods We performed a departmental questionnaire involving 17 consultant anaesthetists and intensivists with experience in the perioperative management of CDH with respect to ‘fitness for surgical repair’. Consultants were asked to define acceptability for anaesthesia and surgical repair in 8 different parameters. Results Of those surveyed, 85% would perform a surgical repair whilst on ≤10ppm of inhaled nitric oxide with a fractional inspired oxygen concentration of ≤0.5 to maintain oxygen saturations of ≥92%. 71% deemed it appropriate to proceed to surgical repair if the pulmonary artery pressures were <2/3 systemic perfusion pressures on weaning doses of pulmonary vasodilators. Also 100% agreed that a mean arterial pressure of ≥45mmHg on weaning doses of inotropes and vasopressors was required. A perioperative hemoglobin level of ≥10g/dl was agreed to be clinically appropriate. A chest x-ray and transthoracic echocardiogram should be performed within 24 hours preoperatively. High frequency oscillatory ventilation was not a contraindication to surgery. Conclusions As a result of this study a consensus document was finalised to delineate a designated care pathway for infants with congenital diaphragmatic hernia.

Oxygen needs during resuscitation and surfactant to achieve stabilisation were independent risks factors for pulmonary interstitial emphysema in preterm infants.

Pulmonary interstitial emphysema is a severe complication of mechanical ventilation in preterm infants that leads to air leakage and, or, chronic lung disease. We determined the associated risk factors. This was a retrospective case-control study from 2005 to 2014 at a regional referral centre in Valencia, Spain. The cases were 54 preterm infants up to 30 weeks' gestation and, or, born weighing less than 1500 g, who were diagnosed with pulmonary interstitial emphysema (PIE). The 54 controls were preterm infants without PIE matched by gestational age. Univariate analysis and multivariate analysis were performed to assess the independent predicting factors. Infants with PIE had been resuscitated with higher mean fractional inspired oxygen concentration (FiO2 ) (p = 0.008), had received higher peak mean positive end expiratory pressure (p = 0.00) and higher mean airway pressure (p = 0.026) 24 hours before diagnosis. PIE patients also received more surfactant (p = 0.00) and had higher mortality (p = 0.034). A Cox regression model identified that independent risk factors were the total amount of surfactant administered and the mean FiO2 during the 24 hours before diagnosis. Independent risk factors for pulmonary interstitial emphysema in preterm infants were higher oxygen during resuscitation and a higher need for surfactant and ventilatory pressures before diagnosis.

A central venous catheter that revealed a vascular paradox

A 60-year-old man with insignificant past medical history, was admitted to the intensive care unit with acute respiratory failure following community-acquired pneumonia. On admission, he was haemodynamically stable in sinus...

Automated control of end-tidal sevoflurane in living donor hepatectomy, a prospective, randomized, controlled study

BackgroundReduction of anesthesia cost has become a necessity, especially in developing countries. Recently, automated control of end-tidal sevoflurane concentration (EtSev) has been proposed as a new technique with both cost-effectiveness and safety profiles. In this study, sevoflurane consumption (primary outcome variable) was evaluated during living donor hepatectomy using automated control of EtSev (EtC) at fresh gas flow (FGF) of 0.5 and 2 L/min compared to manual control (MC) technique at FGF of 2 L/min.Materials and methodsProspective, randomized, controlled trial including 60 Potential donors scheduled for living donor right hepatectomy. patients were randomized into 3 equal groups (according to target control of sevoflurane), MC group, EtC-2L group, and EtC-0.5L group. In MC group: FGF was set to 2 L/min, inspired concentration of Sevoflurane (FiSev) was set to 1.5–2% in 0.4 fractional inspired oxygen concentration (FiO2), while in EtC-2L group: FGF was set to 2 L/min, EtSev was set to 1–1.5% with end tidal oxygen concentration (EtO2) target of 0.35. In EtC-0.5L group, FGF was set to minimal flow and EtSev target to 1–1.5% and EtO2 target of 0.35. Anesthetic gases consumption (sevoflurane ml, Oxygen L, and air consumption L) per anesthesia hour were recorded at the end of surgery. Other recorded data included intraoperative hemodynamics, the number of user adjustments, and extubation time.ResultsSignificant reduction in sevoflurane consumption when EtC-0.5L is used (4.2 ± 1.3 ml/h, 12.6 ± 2.6 ml/h, and 15 ± 2.9 ml/h respectively, p. 0.001). Also, a significant decrease in overall numbers of user adjustments between the three groups (8 times for EtC-0.5L group, 7 times in EtC-2L group, 22 times for MC group, p. 0.008) was observed.Conclusionautomated control of EtSev during anesthesia of living donor hepatectomy significantly lowers sevoflurane consumption and decreases required user interventions without deleterious effect on patient safety.