Respiratory support with nasal high flow without supplemental oxygen in patients undergoing endoscopic retrograde cholangiopancreatography under moderate sedation: a prospective, randomized, single-center clinical trial.

BACKGROUND: Nasal high flow (NHF) may reduce hypoxia and hypercapnia during an endoscopic retrograde cholangiopancreatography (ERCP) procedure under sedation. The authors tested a hypothesis that NHF with room air during ERCP may prevent intraoperative hypercapnia and hypoxemia. METHODS: In the prospective, open-label, single-center, clinical trial, 75 patients undergoing ERCP performed with moderate sedation were randomized to receive NHF with room air (40 to 60 L/min, n = 37) or low-flow O2 via a nasal cannula (1 to 2 L/min, n = 38) during the procedure. Transcutaneous CO2, peripheral arterial O2 saturation, a dose of administered sedative and analgesics were measured. RESULTS: The primary outcome was the incidence of marked hypercapnia during an ERCP procedure under sedation observed in 1 patient (2.7%) in the NHF group and in 7 patients (18.4%) in the LFO group; statistical significance was found in the risk difference (-15.7%, 95% CI -29.1 - -2.4, p = 0.021) but not in the risk ratio (0.15, 95% CI 0.02 - 1.13, p = 0.066). In secondary outcome analysis, the mean time-weighted total PtcCO2 was 47.2 mmHg in the NHF group and 48.2 mmHg in the LFO group, with no significant difference (-0.97, 95% CI -3.35 - 1.41, p = 0.421). The duration of hypercapnia did not differ markedly between the two groups either [median (range) in the NHF group: 7 (0 - 99); median (range) in the LFO group: 14.5 (0 - 206); p = 0.313] and the occurrence of hypoxemia during an ERCP procedure under sedation was observed in 3 patients (8.1%) in the NHF group and 2 patients (5.3%) in the LFO group, with no significant difference (p = 0.674). CONCLUSIONS: Respiratory support by NHF with room air did not reduce marked hypercapnia during ERCP under sedation relative to LFO. There was no significant difference in the occurrence of hypoxemia between the groups that may indicate an improvement of gas exchanges by NHF. TRIAL REGISTRATION: jRCTs072190021 . The full date of first registration on jRCT: August 26, 2019.

Comparison of Two Noninvasive Ventilation Strategies (NHFOV Versus NIPPV) as Initial Postextubation Respiratory Support in High-Risk Infants After Congenital Heart Surgery.

OBJECTIVE: This study aimed to compare the effects of nasal high-frequency oscillatory ventilation (NHFOV) and noninvasive positive-pressure ventilation (NIPPV) as the initial postextubation therapies on preventing extubation failure (EF) in high-risk infants younger than three months after congenital heart surgery (CHS). DESIGN: This was a single-center, randomized, unblinded clinical trial. SETTING: The study was performed in a teaching hospital. PARTICIPANTS: Between January 2020 and January 2021, a total of 150 infants underwent CHS in the authors' hospital. INTERVENTIONS: Infants younger than three months with a high risk for extubation failure who were ready for extubation were randomized to either an NHFOV therapy group or an NIPPV therapy group, and received the corresponding noninvasive mechanical ventilation to prevent EF. MEASUREMENTS: Primary outcomes were reintubation, long-term noninvasive ventilation (NIV) support (more than 72 hours), and the time in NIV therapy. The secondary outcomes were adverse events, including mild-moderate hypercapnia, severe hypercapnia, severe hypoxemia, treatment intolerance, signs of discomfort, unbearable dyspnea, inability to clear secretions, emesis, and aspiration. MAIN RESULTS: Of 92 infants, 45 received NHFOV therapy, and 47 received NIPPV therapy after extubation. There were no significant differences between the NHFOV and the NIPPV therapy groups in the incidences of reintubation, long-term NIV support, and total time under NIV therapy. No significant difference was found of the severe hypercapnia between the two groups, but NHFOV treatment significantly decreased the rate of mild-moderate hypercapnia (p < 0.05). Other outcomes were similar in the two groups. CONCLUSIONS: Among infants younger than three months after CHS who had undergone extubation, NIPPV therapy and NHFOV therapy were the equivalent NIV strategies for preventing extubation failure, and NHFOV therapy was more effective in avoiding mild-moderate hypercapnia.

Guidelines on analgosedation, monitoring, and recovery time for flexible bronchoscopy: a systematic review.

BACKGROUND: Patients undergoing bronchoscopy in spontaneous breathing are prone to hypoxaemia and hypercapnia. Sedation, airway obstruction, and lung diseases impair respiration and gas exchange. The restitution of normal respiration takes place in the recovery room. Nonetheless, there is no evidence on the necessary observation time. We systematically reviewed current guidelines on bronchoscopy regarding sedation, monitoring and recovery. METHODS: This review was registered at the PROSPERO database (CRD42020197476). MEDLINE and awmf.org were double-searched for official guidelines, recommendation or consensus statements on bronchoscopy from 2010 to 2020. The PICO-process focussed on adults (Patients), bronchoscopy with maintained spontaneous breathing (Interventions), and recommendations regarding the intra- and postprocedural monitoring and sedation (O). The guideline quality was graded. A catalogue of 54 questions was answered. Strength of recommendation and evidence levels were recorded for each recommendation. RESULTS: Six guidelines on general bronchoscopy and three expert statements on special bronchoscopic procedures were identified. Four guidelines were evidence-based. Most guidelines recommend sedation to improve the patient's tolerance. Midazolam combined with an opioid is preferred. The standard monitoring consists of non-invasive blood pressure, and pulse oximetry, furthermore electrocardiogram in cardiac patients. Only one guideline discusses hypercapnia and capnometry, but without consensus. Two guidelines discuss a recovery time of two hours, but a recommendation was not given because of lack of evidence. CONCLUSION: Evidence for most issues is low to moderate. Lung-diseased patients are not represented by current guidelines. Capnometry and recovery time lack evidence. More primary research in these fields is needed so that future guidelines may address these issues, too.

Evaluation of hyperoxia-induced hypercapnia in obese patients after cardiac surgery: a randomized crossover comparison of conservative and liberal oxygen administration.

PURPOSE: Recent studies on patients with stable obesity-hypoventilation syndrome have raised concerns about hyperoxia-induced hypercapnia in this population. This study aimed to evaluate whether a higher oxygen saturation target would increase arterial partial pressure of carbon dioxide (PaCO2) in obese patients after coronary artery bypass grafting surgery (CABG). METHODS: Obese patients having CABG were recruited. With a randomized crossover design, we compared two oxygenation strategies for 30 min each, immediately after extubation: a peripheral oxygen saturation (SpO2) target of ≥ 95% achieved with manual oxygen titration (liberal) and a SpO2 target of 90% achieved with FreeO2, an automated oxygen titration device (conservative). The main outcome was end-of-period arterial PaCO2. RESULTS: Thirty patients were included. Mean (standard deviation [SD]) body mass index (BMI) was 34 (3) kg·m-2 and mean (SD) baseline partial pressure of carbon dioxide (PCO2) was 40.7 (3.1) mmHg. Mean (SD) end-of-period PaCO2 was 42.0 (5.4) mmHg in the conservative period, compared with 42.6 (4.6) mmHg in the liberal period [mean difference - 0.6 (95% confidence interval - 2.2 to 0.9) mmHg; P = 0.4]. Adjusted analysis for age, BMI, narcotics, and preoperative PaCO2 did not substantively change the results. Fourteen patients were retainers, showing an elevation in mean (SD) PaCO2 in the liberal period of 3.3 (4.1) mmHg. Eleven patients had the opposite response, with a mean (SD) end-of-period PaCO2 decrease of 1.8 (2.2) mmHg in the liberal period. Five patients had a neutral response. CONCLUSION: This study did not show a clinically important increase in PaCO2 associated with higher SpO2 values in this specific population of obese patients after CABG. Partial pressure of carbon dioxide increased with liberal oxygen administration in almost half of the patients, but no predictive factor was identified. TRIAL REGISTRATION: www.clinicaltrials.gov (NCT02917668); registered 25 September, 2016.

Derivation and validation of an equation to determine the optimal ventilator setting in children undergoing intracranial revascularization surgery: A single-center retrospective study.

BACKGROUND: It can be difficult to determine the appropriate ventilator settings to maintain normocapnia in children undergoing general anesthesia for surgery for moyamoya disease, especially immediately following anesthesia induction. AIM: We conducted this study to attempt to derive an equation to predict the appropriate ventilator settings and subsequently validated the accuracy of the equation. METHODS: A retrospective study of 91 pediatric patients less than 18 years of age who underwent cerebral revascularization for moyamoya disease at our institution. Fifty-eight patients were used to derive the equation, and the subsequent 33 patients were used to validate the equation. We calculated the required respiratory rate to attain normocapnia based on the median of all values of the minute volume during normocapnia (estimated partial pressure of arterial carbon dioxide of 38-42 mm Hg) and the assumption that the tidal volume was 8 mL/kg body weight. We derived the regression equation from the derivation data set where the required respiratory rate to attain normocapnia was represented by age. We simplified the equation by rounding coefficients to the nearest integer. The level of agreement between the respiratory rate predicted from the equation and the actual required respiratory rate was assessed in the validation group using Bland-Altman analysis. RESULTS: The derived equation is tidal volume = 8 mL/kg body weight, respiratory rate = 24-age/min. Bland-Altman analysis in the validation group revealed that the mean bias between the predicted and actual respiratory rate was 0.29 (standard deviation, 3.67). The percentage of cases where the predicted rate was within ± 10% and ± 20% of the actual rate was 42.4% and 66.7%, respectively. CONCLUSIONS: We derived and validated a simple and easily applicable equation to predict the ventilator settings required to attain normocapnia during general anesthesia in children with moyamoya disease.

[Differential Therapy NIV - NHF]. / Differenzialtherapie nicht-invasive Beatmung ­ nasale High-Flow-Therapie.

Nasal high-flow provides a stable oxygenation in acute hypoxemic respiratory failure, modifies breathing patterns, reduces work of breathing and can decrease hypercapnia. Thereby NHF provides more features than low-flow oxygen and acts as a ventilatory support device. Different studies show benefits of NHF compared to NIV. For these reasons we will discuss the capabilities of NHF and NIV in selected settings.

Non-invasive ventilation versus oxygen therapy in cystic fibrosis: A 12-month randomized trial.

BACKGROUND AND OBJECTIVE: No published studies have examined the long-term effects of non-invasive ventilation (NIV) in cystic fibrosis (CF). Our primary aim was to determine if adults with CF and sleep desaturation were less likely to develop hypercapnia with NIV ± O2 compared to low-flow oxygen therapy (LFO2 ) or meet the criteria for failure of therapy over 12 months. We studied event-free survival, hospitalizations, lung function, arterial blood gases (ABG), sleep quality and health-related quality of life. METHODS: A prospective, randomized, parallel group study in adult patients with CF and sleep desaturation was conducted, comparing 12 months of NIV ± O2 to LFO2 . Event-free survival was defined as participants without events. Events included: failure of therapy with PaCO2 > 60 mm Hg, or increase in PaCO2 > 10 mm Hg from baseline, increases in TcCO2 > 10 mm Hg, lung transplantation or death. Outcomes were measured at baseline, 3, 6 and 12 months, including lung function, ABG, Pittsburgh Sleep Quality Inventory (PSQI), SF36 and hospitalizations. RESULTS: A total of 29 patients were randomized to NIV ± O2 (n = 14) or LFO2 (n = 15) therapy for 12 months. Of the 29 patients, 18 met the criteria for event-free survival over 12 months. NIV ± O2 group had 33% (95% CI: 5-58%) and 46% (95% CI: 10-68%) more event-free survival at 3 and 12 months than LFO2 group. No statistically significant differences were seen in spirometry, ABG, questionnaires or hospitalizations. CONCLUSION: NIV ± O2 during sleep increases event-free survival over 12 months in adults with CF. Further studies are required to determine which subgroups benefit the most from NIV.

An audit of change in clinical practice: from oxygen-driven to air-driven nebulisers for prehospital patients with acute exacerbations of chronic obstructive pulmonary disease (AECOPD).

BACKGROUND: In developed countries, ambulances normally carry oxygen cylinders, but not compressed air. Treatment of acute exacerbations of chronic obstructive pulmonary disease (AECOPD) with oxygen-driven nebulisers can result in hypercapnia and acidosis. Attempts to avoid this have involved interrupted administration of oxygen. However, small battery-powered air nebulisers are now available. This study aims to compare the prehospital oxygen saturations and treatment of patients suffering from AECOPD before and after the introduction of air nebulisers. METHODS: The oxygen saturations and treatment of 200 AECOPD patients before and 200 AECOPD patients after the introduction of air nebulisers were compared. Compliance with a target saturation of 88-92% was calculated. RESULTS: The median final oxygen saturation was lower for the post-intervention category (94%) than the pre-intervention category (96%). There was an increase in air nebuliser use from 0 to 56% (P < 0.001) and a decrease in oxygen use from 100 to 71.5% (P < 0.001). There was a numerical increase in the proportion of patients arriving at hospital with oxygen saturations of 88-92% following introduction of the air nebulisers (24 vs 16.5%) and a decrease in patients arriving with high saturations (67.5 vs 76.5%). The likelihood of achieving the target oxygen saturations following introduction of air nebulisers increased (odds ratio 1.598; 95% confidence interval 0.974, 2.621). CONCLUSION: The introduction of prehospital air nebulisers resulted in a reduction in oxygen therapy in patients with AECOPD and a lower median prehospital oxygen saturation. This study supports the use of air nebulisers in the prehospital setting.

Titration of oxygen therapy in critically ill emergency department patients: a feasibility study.

BACKGROUND: Liberal use of oxygen in an emergency situation is common. Today, most health care professionals do not adjust the amount of oxygen given when a saturation of 100% or a PaO2 which exceeds the normal range is reached- which may result in hyperoxia. There is increasing evidence for the toxic effects of hyperoxia. Therefore, it seems justified to aim for normoxia when giving oxygen. This study evaluates whether it is feasible to aim for normoxia when giving oxygen therapy to patients at the emergency department (ED). METHODS: A prospective cohort study was performed at the ED of the University Medical Center Groningen (UMCG). A protocol was developed, aiming for normoxia. During a 14 week period all patients > 18 years arriving at the ED between 8 a.m. and 23 p.m. requiring oxygen therapy registered for cardiology, internal medicine, emergency medicine and pulmonology were included. Statistical analysis was performed using student independent t-test, Mann-Whitney U-test, Fisher's exact test or a Pearson's chi-squared test. RESULTS: During the study period the study protocol was followed and normoxia was obtained after 1 h at the ED in 86,4% of the patients. Patients with COPD were more at risk for not being titrated to normal oxygen levels. CONCLUSIONS: We showed that it is feasible to titrate oxygen therapy to normoxia at the ED. The study results will be used for further research assessing the potential beneficial effects of normoxia compared to hyper- or hypoxia in ED patients and for the development of guidelines.

Overcoming sleep disordered breathing and ensuring sufficient good sleep time for a healthy life expectancy.

Recent advances in basic and clinical medicine have resulted in major improvements in human health. Currently sleep has been considered an essential factor in maintaining and promoting a healthy life expectancy. Sleep disorders include more than 60 diseases. Sleep disordered breathings (SDB) have 17 disorders, including sleep apnea. SDB usually induces hypoxemia and hypercapnia, which would have significant effects on cells, organs, and the whole body. We have investigated SDB for nearly 35 years. We found that SDB has significant associations with humoral factors, including coagulation systems, the body's protective factors against diseases, and metabolic and organ diseases. Currently we have been giving attention to the associations among SDB, short sleep duration, and obesity. In addition, SDB is important not only in the home but under critical care such as in the perioperative stage. In this review, I would like to describe several aspects of SDB in relation to systemic diseases and overall health based mainly on our published reports.

Episodes of hypo- and hypercapnia in a cohort of mechanically ventilated VLBW infants: the role of adequate staffing.

In preterm neonates, the use of invasive ventilation may be mandatory because of respiratory distress syndrome (RDS). In this short communication, we demonstrate that invasive ventilation in this susceptible cohort may be associated with episodes of both hypo- and hypercapnia, and that inadequate ventilatory support is associated with the occurrence rate of bronchopulmonary dysplasia (BPD; p < 0.05). Also, inadequate mechanical ventilation is aggravated by a shortage of medical staff.

Applying a low-flow CO2 removal device in severe acute hypercapnic respiratory failure.

A novel and portable extracorporeal CO2-removal device was evaluated to provide additional gas transfer, auxiliary to standard therapy in severe acute hypercapnic respiratory failure. A dual-lumen catheter was inserted percutaneously in five subjects (mean age 55 ± 0.4 years) and, subsequently, connected to the CO2-removal device. The median duration on support was 45 hours (interquartile range 26-156), with a blood flow rate of approximately 500 mL/min. The mean PaCO2 decreased from 95.8 ± 21.9 mmHg to 63.9 ± 19.6 mmHg with the pH improving from 7.11 ± 0.1 to 7.26 ± 0.1 in the initial 4 hours of support. Three subjects were directly weaned from the CO2-removal device and mechanical ventilation, one subject was converted to ECMO and one subject died following withdrawal of support. No systemic bleeding or device complications were observed. Low-flow CO2 removal adjuvant to standard therapy was effective in steadily removing CO2, limiting the progression of acidosis in subjects with severe acute hypercapnic respiratory failure.

Transcutaneous continuous carbon dioxide tension monitoring reduced incidence, degree and duration of hypercapnia during combined regional anaesthesia and monitored anaesthesia care in shoulder surgery patients.

We studied the impact of transcutaneous continuous carbon dioxide tension (PtcCO2) monitoring on ventilation and oxygenation during monitored anaesthesia care (MAC) in patients scheduled for shoulder surgery with continuous interscalene block. 50 patients were randomised either to the intervention (I-group) or the control (C-group) group. In both groups MAC was performed using target controlled infusion of propofol and remifentanil. MAC regimen was adapted to PtcCO2 values in the I-group, whereas the C-group was blinded for these values. Primary outcome was the incidence, degree and duration of hypoventilation stages. In the I-group and the C-group the mean ± SD [range] of PtcCO2 and PaCO2 was 5.79 ± 0.84 [4.37] and 5.44 ± 0.59 [2.78] kPa, as well as 6.41 ± 1.17 [6.29] and 6.01 ± 0.96 [7.15] kPa. Periods of PtcCO2/PaCO2 > 6.5 kPa were 21.0 ± 35.7/1.2 ± 4.2 min in the I-group and 45.6 ± 40.0/18.6 ± 26.8 min in the C-group. Severe hypercapnia (PtcCO2 and/or PaCO2 > 7.5 kPa) was dected in 3/0 patients of the I-group and in 10/3 patients of the C-group. PtcCO2 and PaCO2 showed a strong correlation (r = 0.78), but only moderate agreement with a mean bias (LOA) of -0.37 (-1.69; +0.95) kPa showing an overestimation of the PaCO2. Sensitivity and specificity of PtcCO2 to detect changes of PaCO2 was 0.94 and 0.56, respectively. In no patient SpO2 or SaO2 values lower than 90% were measured. Despite a moderate agreement between PaCO2 and PtcCO2 the PtcCO2 monitoring significantly reduced incidence, degree and duration of hypercapnia in shoulder surgery patients with MAC.

The impact of oxygen and carbon dioxide management on outcome after cardiac arrest.

PURPOSE OF REVIEW: To describe the impact of oxygen and carbon dioxide management on patient outcomes following cardiac arrest. RECENT FINDINGS: Although there are no data that suggest that supplemental oxygen administration during cardiopulmonary resuscitation is harmful, there is concern that 100% oxygen during the postresuscitation phase may be undesirable. The evidence to avoid hyperoxia is limited to animal studies and retrospective clinical studies that examine the association between exposure and outcome. There is a correlation between end-tidal carbon dioxide values during cardiopulmonary resuscitation and resuscitation outcome, yet this correlation is likely to reflect low or absent cardiac output and be a biomarker of illness severity rather than a mediator of injury. Additionally, very limited high-level human data exist on the relationship between arterial carbon dioxide tension and outcome following cardiac arrest. Retrospective studies have identified hypocapnia in the intensive care unit as being independently associated with worse neurological and mortality outcomes in cardiac arrest patients. Although there appears to be sufficient evidence to recommend avoiding hypocapnia after resuscitation, observational data suggest that hypercapnia may be independently associated with a greater likelihood of discharge home amongst cardiac arrest survivors. SUMMARY: Current data for oxygen and carbon dioxide management following resuscitation suggest that hyperoxia and hypocapnia may be injurious and should be avoided, and that mild hypercapnia may increase the likelihood of discharge home amongst survivors. Such data should be viewed as hypothesis generating. Randomized controlled trials have commenced to clarify the safety, feasibility and efficacy of targeting different oxygen and carbon dioxide tensions following cardiac arrest.

Continuous positive airway pressure/pressure support pre-oxygenation of morbidly obese patients.

BACKGROUND: Morbidly obese patients are more prone to desaturation of arterial blood during apnea with induction of anesthesia than are non-obese. This study aimed to assess the effect of low-pressure continuous positive airway pressure (CPAP) with pressure support ventilation (PSV) during pre-oxygenation on partial oxygen pressure in arterial blood (PaO2 ) immediately after tracheal intubation (post-intubation PaO2). METHODS: Forty-four adult patients scheduled for laparoscopic gastric bypass surgery were pre-oxygenated with 80% O2 for 2 min, randomized either to CPAP 5 cm H2O + PSV 5 cm H2O (CPAP/PSV, n = 22) or neutral-pressure breathing without CPAP/PSV (control, n = 22). Anesthesia was induced in a rapid-sequence protocol and the trachea was intubated without prior mask ventilation. Arterial blood gases were measured before pre-oxygenation, before induction of anesthesia, and immediately following intubation, before the first positive pressure breath. RESULTS: After pre-oxygenation, partial carbondioxide pressure was significantly lower in the CPAP/PSV group (4.9 ± 0.5 kPa), (mean ± standard deviation) than in the control group (5.2 ± 0.7 kPa) (P = 0.025). Post-preoxygenation PaO2 did not differ between the groups, but post-intubation PaO2 was significantly higher in the CPAP/PSV group (32.2 ± 4.1 kPa) than in the control group (23.8 ± 8.8 kPa) (P < 0.001). In the control group, nadir oxygen saturation was lower (median 98%, range 83-99%) than in the CPAP/PSV group (median 99%, range 97-99%, P = 0.011). CONCLUSIONS: In morbidly obese patients, low-pressure CPAP combined with low-pressure PSV during pre-oxygenation resulted in better oxygenation, compared with neutral-pressure breathing, and prevented desaturation episodes.

[The comparative investigation of antihypoxia activity of glutamic and N-acetylglutamic acids].

Comparative study of antihypoxic activity of glutamic and N-acetylglutamic acid in doses of 1, 10, 50 and 100 mg/kg was realized. It was experimentally ascertained that the most apparent antihypoxic action of study objects occurs in conditions of hypobaric hypoxia of acetylated derivative of glutamic acid considerably exceeds glutamic acid.

Examination of stabilization of sedation by Nasal High Flow in patients with endoscopic retrograde cholangiopancreatography during sedation using Dexmedetomidine.

INTRODUCTION: Dexmedetomidine is used for the sedation method in the case of endoscopic retrograde cholangiopancreatography (ERCP) for the purpose of relieving patient anxiety. It has been reported that CO2 accumulated during sedation causes an arousal reaction, so how to normalize CO2 during sedation can be improved by administration of the minimum necessary sedative.Nasal High Flow oxygen therapy (NHF) uses a mild positive pressure load that improves carbon dioxide washout and reduces rebreathing to improve respiratory function and therefore is widely used to prevent hypoxemia and hypercapnia. In this study, we will investigate whether the upper airway patency would be maintained and the hypercapnia and hypoxemia during sedation would be prevented, by applying NHF as a respiratory management method to patients undergoing ERCP under sedation. METHODS/DESIGN: In a randomized comparative study of 2 groups, the NHF device use group and the nasal cannula use group, for adult patients who visited the Nagasaki University Hospital and underwent ERCP examination under sedation. For sedation, Dexmedetomidine will be used in combination with and Midazolam and evaluation by anesthesiologist. In addition, as an analgesic, pethidine hydrochloride was administered intravenously. The total dose of the analgesic pethidine hydrochloride used in combination is used as the primary endpoint. As a secondary evaluation item, the percutaneous CO2 concentration is evaluated with a TCO2 monitor to examine whether it is effective in preventing hypercapnia. Furthermore, we will evaluate the incidence of hypoxemia with a percutaneous oxygen saturation value of 90% or less, and examine whether the use of equipment is effective in preventing the occurrence of hypercapnia and hypoxemia. DISCUSSION: The purpose of this study was to obtain evidence for the utility of NHF as a potential therapeutic device for patients undergoing an ERCP under sedation, assessed by determining if the incidence rates of hypercapnia and hypoxemia decreased in the NHF device group, compared to the control group that did not use of this device.

[Similarity of cycloprolylglycine to piracetam in antihypoxic and neuroprotective effects].

The antihypoxic activity of the endogenous cyclic dipeptide cycloprolylglycine (CPG) has been studied on a model of normobaric hypoxia with hypercapnia and its neuroprotective activity has been studied on a model of human neuroblastoma SH-SY5Y cell damage by 6-hydroxydopamine. It is established that CPG exhibits the antihypoxic activity at doses of 0.5 and 1.0 mg/kg (i.p.) on outbred and BALB/c mice, but not on C57B1/6 mice. The neuroprotective activity of CPG was detected in 10(-5) - 10(-8) M concentration range only when the treatment was carried out 24h before toxin introduction. The obtained data confirm the hypothesis that piracetam is a mimetic of the endogenous CPG neuropeptide.