Capnometric feedback training decreases 24-h blood pressure in hypertensive postmenopausal women.

BACKGROUND: High normal resting pCO2 is a risk factor for salt sensitivity of blood pressure (BP) in normotensive humans and has been associated with higher resting systolic BP in postmenopausal women. To date, however, no known studies have investigated the effects of regular practice of voluntary mild hypocapnic breathing on BP in hypertensive patients. The objective of the present research was to test the hypothesis that capnometric feedback training can decrease both resting pCO2 and 24-h BP in a series of mildly hypertensive postmenopausal women. METHODS: A small portable end tidal CO2 (etCO2) monitor was constructed and equipped with software that determined the difference between the momentary etCO2 and a pre-programmed criterion range. The monitor enabled auditory feedback for variations in CO2 outside the criterion range. 16 mildly hypertensive postmenopausal women were individually trained to sustain small decreases in etCO2 during six weekly sessions in the clinic and daily sessions at home. 24-h BP monitoring was conducted before and after the intervention, and in 16 prehypertensive postmenopausal women in a control group who did not engage in the capnometric training. RESULTS: Following the intervention, all 16 capnometric training participants showed decreases in resting etCO2 (- 4.3 ± 0.4 mmHg; p < .01) while 15 showed decreases in 24-h systolic BP (- 7.6 ± 2.0 mmHg; p < .01). No significant changes in either measure was observed in the control group. In addition, nighttime (- 9.5 ± 2.6; p < .01) and daytime (- 6.7 ± 0.2 mmHg) systolic BP were both decreased following capnometric training, while no significant changes in nighttime (- 2.8 ± 2.2 mmHg; p = .11) or daytime (- 0.7 ± 1.0 mmHg; p ≤ .247) systolic BP were observed in the control group. CONCLUSIONS: These findings support the hypothesis that regular practice of mild hypocapnic breathing that decreases resting etCO2 reliably decreases 24-h blood pressure in hypertensive postmenopausal women. The extent to which these effects persist beyond the training period or can be observed in other hypertensive subgroups remains to be investigated.

Changes in acid-base status in oxygen toxicity at 230 kPa oxygen as a function of exposure time.

Breathing less than 50 kPa of oxygen over time can lead to pulmonary oxygen toxicity (POT). Vital capacity (VC) as the sole parameter for POT has its limitations. In this study we try to find out the changes of acid-base status in a POT rat model. Fifty male rats were randomly divided into five groups, exposed to 230 kPa oxygen for three, six, nine and 12 hours, respectively. Rats exposed to air were used as controls. After exposure the mortality and behavior of rats were observed. Arterial blood samples were collected for acid-base status detection and wet-dry (W/D) ratios of lung tissues were tested. Results showed that the acid-base status in rats exposed to 230 kPa oxygen presented a dynamic change. The primary status was in the compensatory period when primary respiratory acidosis was mixed with compensated metabolic alkalosis. Then the status changed to decompensated alkalosis and developed to decompensated acidosis in the end. pH, PCO2, HCO3-, TCO2, and BE values had two phases: an increase and a later decrease with increasing oxygen exposure time, while PaO2 and lung W/D ratio showed continuously increasing trends with the extension of oxygen exposure time. Lung W/D ratio was significantly associated with PaO2 (r = 0.6385, p = 0.002), while other parameters did not show a significant correlation. It is concluded that acid-base status in POT rats presents a dynamic change: in the compensatory period first, then turns to decompensated alkalosis and ends up with decompensated acidosis status. Blood gas analysis is a useful method to monitor the development of POT.

Is carbonic anhydrase inhibition useful as a complementary therapy of Covid-19 infection?

The ongoing Covid-19 is a contagious disease, and it is characterised by different symptoms such as fever, cough, and shortness of breath. Rising concerns about Covid-19 have severely affected the healthcare system in all countries as the Covid-19 outbreak has developed at a rapid rate all around the globe. Intriguing, a clinically used drug, acetazolamide (a specific inhibitor of carbonic anhydrase, CA, EC 4.2.1.1), is used to treat high-altitude pulmonary oedema (HAPE), showing a high degree of clinical similarities with the pulmonary disease caused by Covid-19. In this context, this preliminary study aims to provide insights into some factors affecting the Covid-19 patients, such as hypoxaemia, hypoxia as well as the blood CA activity. We hypothesise that patients with Covid-19 problems could show a dysregulated acid-base status influenced by CA activity. These preliminary results suggest that the use of CA inhibitors as a pharmacological treatment for Covid-19 may be beneficial.

D-Cystine di(m)ethyl ester reverses the deleterious effects of morphine on ventilation and arterial blood gas chemistry while promoting antinociception.

We have identified thiolesters that reverse the negative effects of opioids on breathing without compromising antinociception. Here we report the effects of D-cystine diethyl ester (D-cystine diEE) or D-cystine dimethyl ester (D-cystine diME) on morphine-induced changes in ventilation, arterial-blood gas chemistry, A-a gradient (index of gas-exchange in the lungs) and antinociception in freely moving rats. Injection of morphine (10 mg/kg, IV) elicited negative effects on breathing (e.g., depression of tidal volume, minute ventilation, peak inspiratory flow, and inspiratory drive). Subsequent injection of D-cystine diEE (500 µmol/kg, IV) elicited an immediate and sustained reversal of these effects of morphine. Injection of morphine (10 mg/kg, IV) also elicited pronounced decreases in arterial blood pH, pO2 and sO2 accompanied by pronounced increases in pCO2 (all indicative of a decrease in ventilatory drive) and A-a gradient (mismatch in ventilation-perfusion in the lungs). These effects of morphine were reversed in an immediate and sustained fashion by D-cystine diME (500 µmol/kg, IV). Finally, the duration of morphine (5 and 10 mg/kg, IV) antinociception was augmented by D-cystine diEE. D-cystine diEE and D-cystine diME may be clinically useful agents that can effectively reverse the negative effects of morphine on breathing and gas-exchange in the lungs while promoting antinociception. Our study suggests that the D-cystine thiolesters are able to differentially modulate the intracellular signaling cascades that mediate morphine-induced ventilatory depression as opposed to those that mediate morphine-induced antinociception and sedation.

The effect of an airflow restriction mask (ARM) on metabolic, ventilatory, and electromyographic responses to continuous cycling exercise.

This study analyzed the physiological adjustments caused by the use of the Elevation training mask® (2.0), an airflow restriction mask (ARM) during continuous exercise. Eighteen physically active participants (12 men and 6 women) were randomized to two protocols: continuous exercise with mask (CE-ARM) and continuous exercise without mask (CE). Exercise consisted of cycling for 20 minutes at 60% of maximum power. Metabolic variables, lactate, and gas concentration were obtained from arterialized blood samples at pre and post exercise. Continuous expired gases and myoelectric activity of the quadriceps were performed at rest and during the test. We observed no reduction in oxygen saturation in CE-ARM, leading to lower pH, higher carbon dioxide, and greater hematocrit (all p <0.05). The expired gas analysis shows that the CE-ARM condition presented higher oxygen uptake and expired carbon dioxide concentrations (p <0.05). The CE-ARM condition also presented lower ventilatory volume, ventilatory frequency, and expired oxygen pressure (p <0.05). No changes in electromyography activity and lactate concentrations were identified. We conclude that using ARM does not induce hypoxia and represents an additional challenge for the control of acid-base balance, and we suggest the use of ARM as being suitable for respiratory muscle training.

An explicitly multi-component arterial gas embolus dissolves much more slowly than its one-component approximation.

We worked out the growth and dissolution rates of an arterial gas embolism (AGE), to illustrate the evolution over time of its size and composition, and the time required for its total dissolution. We did this for a variety of breathing gases including air, pure oxygen, Nitrox and Heliox (each over a range of oxygen mole fractions), in order to assess how the breathing gas influenced the evolution of the AGE. The calculations were done by numerically integrating the underlying rate equations for explicitly multi-component AGEs, that contained a minimum of three (water, carbon dioxide and oxygen) and a maximum of five components (water, carbon dioxide, oxygen, nitrogen and helium). The rate equations were straight-forward extensions of those for a one-component gas bubble. They were derived by using the Young-Laplace equation and Dalton's law for the pressure in the AGE, the Laplace equation for the dissolved solute concentration gradients in solution, Henry's law for gas solubilities, and Fick's law for diffusion rates across the AGE/arterial blood interface. We found that the 1-component approximation, under which the contents of the AGE are approximated by its dominant component, greatly overestimates the dissolution rate and underestimates the total dissolution time of an AGE. This is because the 1-component approximation manifestly precludes equilibration between the AGE and arterial blood of the inspired volatile solutes (O2, N2, He) in arterial blood. Our calculations uncovered an important practical result, namely that the administration of Heliox, as an adjunct to recompression therapy for treating a suspected N2-rich AGE must be done with care. While Helium is useful for preventing nitrogen narcosis which can arise in aggressive recompression therapy wherein the N2 partial pressure can be quite high (e.g.∼5 atm), it also temporarily expands the AGE, beyond the expansion arising from the use of Oxygen-rich Nitrox. For less aggressive recompression therapy wherein nitrogen narcosis is not a significant concern, Oxygen-rich Nitrox is to be preferred, both because it does not temporarily expand the AGE as much as Heliox, and because it is much cheaper and more conservation-minded.

Derangement of PaCO2 requires physician attention in acute carbon monoxide poisoning.

The objective was to describe the prevalence of derangement of the partial pressure of arterial carbon dioxide (PaCO2) and to determine the association between PaCO2 and adverse cardiovascular events (ACVEs) in carbon monoxide (CO)-poisoned patients. Additionally, we evaluated whether the derangement of PaCO2 was simply secondary to metabolic changes. This retrospective study included 194 self-breathing patients after CO poisoning with an indication for hyperbaric oxygen therapy and available arterial blood gas analysis at presentation and 6 h later. The incidence rate of hypocapnia at presentation after acute CO poisoning was 67.5%, and the mean PaCO2 during the first 6 h was 33 (31-36.7) mmHg. The most common acid-base imbalance in 131 patients with hypocapnia was primary respiratory alkalosis. The incidence rate of ACVEs during hospitalization was 50.5%. A significant linear trend in the incidence of ACVEs was observed across the total range of PaCO2 variables. In multivariate regression analysis, mean PaCO2 was independently associated with ACVEs (odds ratio 0.051; 95% confidence interval 0.004-0.632). PaCO2 derangements were common after acute CO poisoning and were not explainable as a mere secondary response to metabolic changes. The mean PaCO2 during the first 6 h was associated with ACVEs. Given the high incidence of ACVEs and PaCO2 derangement and the observed association between the mean PaCO2 and ACVEs, this study suggests that (1) PaCO2 should be monitored in the acute stage to predict and/or prevent ACVEs and (2) further investigation is needed to validate this result and explore the early manipulation of PaCO2 as a treatment strategy.

Pregnancy profiles in the common bottlenose dolphin (Tursiops truncatus): Clinical biochemical and hematological variations during healthy gestation and a successful outcome.

The physiological demands of pregnancy inevitably result in changes of both biochemical and hematological parameters as the fetus develops. Alterations in blood parameters have been observed to shift according to both trimester and species, to support fetal physiological needs and maternal basal requirements. Establishing normal reference ranges for each stage in gestation is important to facilitate diagnosis of underlying health concerns and prevent over-diagnosing abnormalities. Despite bottlenose dolphins (Tursiops truncatus) being one of the most highly studied cetaceans, the blood profile changes occurring as a result of pregnancy have not been previously described. A retrospective analysis was performed from blood samples obtained from 42 successful pregnancies from 20 bottlenose dolphins in a managed population over 30 years. Samples were compared to non-pregnant states and among trimesters of pregnancy. Blood profile fluctuations occurred throughout gestation, however significant alterations predominantly occurred between the 2nd and 3rd trimester. Hematological changes from the 2nd to the 3rd trimester included a decrease in lymphocytes, decrease in platelet count, and hemoconcentration with increased hematocrit and hemoglobin. Biochemical changes in the 3rd trimester included significant reductions in ALKP (alkaline phosphatase), ALT (alanine aminotransferase) and AST (aspartate aminotransferase) with significant increases observed in albumin, globulins, total protein, cholesterol, triglycerides and CO2. It's important to note that despite significant shifts occurring between the 2nd and 3rd trimester, there was no significant change in platelets, hematocrit, hemoglobin, lymphocytes or CO2 between non-pregnant and 3rd trimester blood samples. The normal reference ranges for each trimester established herein, will enable future identification of abnormalities occurring during pregnancy and help improve our understanding of factors potentially influencing a failed or successful pregnancy outcome.

Comparison of respiratory parameters in participants with and without chronic low back pain.

BACKGROUND: Individuals with chronic low back pain (CLBP) may lack coordination between the stabilising and respiratory functions of trunk muscles. The trunk stabilisers compromise breathing to maintain spinal stability, leading to breathing dysfunctions. Maximal voluntary ventilation (MVV) is indicative of the respiratory muscle endurance and strength whereas end-tidal carbon dioxide (PETCO2) gives an estimate of breathing patterns that closely reflect the arterial measurement of CO2. CLBP has been shown to have a significant effect on respiratory functions. However, the impact has not yet been quantified. Further, there is a dearth of literature comparingrespiratory functions between CLBP and healthy individuals. This study investigates respiratory functions in participants with and without CLBP. METHODS: The study compared the respiratory functions of maximal voluntary ventilation (MVV) and End-Tidal Carbon Dioxide (PETCO2) between 14 participants with CLBP and 14 healthy individuals. Participants in both groups were matched for age, height, weight and body surface area. The assessment of MVV and PETCO2 were performed sitting, standing on a stable surface, and on an unstable surface (BOSU ball). RESULTS: The mean of measured MVV (L/min) was found to be lower (p < 0.05) in the CLBP group when compared to the healthy group. Mean PETCO2 and respiratory rate was found to be higher in CLBP group when compared to the healthy group in all three positions, although this was not found to be statistically significant. CONCLUSION: The findings of this study demonstrated sub-optimal respiratory parameters in participants with chronic low back pain. However, when adjusted for gender, the difference was not found to be significant between the two groups.

Efficacy of acupoint massage combined with acupoint application on arterial blood gas in patients undergoing laparoscopic cholecystectomy.

To explore efficacy of acupoint massage combined with acupoint application on arterial blood gas and postoperative complications for patients undergoing laparoscopic cholecystectomy. Patients undergoing laparoscopic cholecystectomy (LC) in general anesthesia condition were randomly enrolled from local hospital into control group and experimental group. Four acupuncture points were prepared for acupoint massage and acupoint application, including bilateral Hegu acupoint (LI4), Neiguan Point (PC6), Zusanli Point (ST36) and Tanzhong acupoint (CV17). All patients in experimental group were treated with point acupressure treatment combined with acupoint application before LC, while control group directly receive LC surgery. The peak inspiratory pressure (PIP), end-tidal CO2 pressure (PETCO2), oxygen saturation (SpO2) and pH were examined at multiple time points during LC surgery. Related postoperative complications were documented for further analysis. All data were analyzed to assess efficacy of acupoint massage combined with acupoint application on arterial blood gas. There is no difference in baseline condition between experimental group and control group. Compared with control group, PetCO2 and SpO2 in experimental group were significantly increased while PIP was decreased. PH in experimental group ranged in a more stable domain. Hypercapnia and deep venous thrombosis were mitigated in experimental group compared with control group. Moreover, multiple pneumoperitoneum-related complications were alleviated after combined treatment, including pain and frequency of nausea and vomiting. Acupoint massage combined with acupoint application ameliorated related postoperative complications, and reduced side events of LC surgery via improving carbon dioxide metabolism.

Adjuvant therapy efficacy of Chinese drugs pharmaceutics for COPD patients with respiratory failure: a meta-analysis.

We performed a meta-analysis to evaluate the efficacy and safety of Western medicine combined with Tanreqing for patients with chronic obstructive pulmonary disease (COPD) and respiratory failure. We comprehensively searched several online databases from the times of their inception to November 2018. The trial quality was assessed using the bias risk tool recommended by the Cochrane library. Relative risks (RRs) and their 95% confidence intervals (CIs) for binary outcomes and weighted mean differences (MDs) with 95% CIs for continuous data were calculated. A fixed effect model indicated that integrated Tanreqing group experienced higher overall treatment effectiveness (RR = 1.23, 95% CI: 1.17-1.30, P=0.000). Pooled results from random effects models indicated the oxygen partial pressure of the test group was significantly higher than that of the control groups (MD = 9.55, 95% CI: 4.57-14.52, P<0.000). The carbon dioxide pressure of the test group was significantly lower than that of the control groups (MD = -6.06, 95% CI: -8.19 to -3.93, P=0.000). The lung function score of the test group was significantly higher than that of the control group (MD = 7.87, 95% CI: 4.45-11.29). Sensitivity analysis indicated that the data were statistically robust. Clinical effects of Western medicine combined with Tanreqing used to treat combined COPD/respiratory failure were better than those afforded by Western medicine; no serious adverse reactions were noted. However, publication bias was evident, and further trials with larger sample sizes are required.

Sucrose but Not Nitrate Ingestion Reduces Strenuous Cycling-induced Intestinal Injury.

PURPOSE: Strenuous exercise induces intestinal injury, which is likely related to splanchnic hypoperfusion and may be associated with gastrointestinal complaints commonly reported during certain exercise modalities. Increasing circulating nitric oxide (NO) levels or inducing postprandial hyperemia may improve splanchnic perfusion, thereby attenuating intestinal injury during exercise. Therefore, we investigated the effects of both dietary nitrate ingestion and sucrose ingestion on splanchnic perfusion and intestinal injury induced by prolonged strenuous cycling. METHODS: In a randomized crossover manner, 16 well-trained male athletes (age, 28 ± 7 yr; Wmax, 5.0 ± 0.3 W·kg) cycled 60 min at 70% Wmax after acute ingestion of sodium nitrate (NIT; 800 mg NO3), sucrose (SUC; 40 g), or a water placebo (PLA). Splanchnic perfusion was assessed by determining the gap between gastric and arterial pCO2 (gapg-apCO2) using gastric air tonometry. Plasma intestinal fatty acid-binding protein (I-FABP) concentrations, reflecting enterocyte damage, were assessed every 20 min during and up to 60 min of postexercise recovery. RESULTS: The exercise protocol resulted in splanchnic hypoperfusion, as gapg-apCO2 levels increased during exercise (P < 0.001), with no differences between treatments (P = 0.47). Although plasma I-FABP concentrations increased during exercise and postexercise recovery for all treatments (P < 0.0001), the increase was different between treatments (P < 0.0001). Post hoc comparisons showed an attenuated increase in I-FABP in SUC versus PLA (P = 0.020). In accordance, I-FABP area under the curve (AUC0-120) was significantly lower in SUC versus PLA (57,270 ± 77,425 vs 114,907 ± 91,527 pg·mL per 120 min, P = 0.002). No differences were observed between NIT and PLA (P = 0.99). CONCLUSION: Sucrose but not nitrate ingestion lowers intestinal injury evoked during prolonged strenuous cycling. These results suggest that sucrose ingestion, but not nitrate, prevents hypoperfusion-induced gastrointestinal damage during exercise and, as such, may help to lower exercise-related gastrointestinal complaints.

The role of umbilical cord gas studies in the prediction of adverse neonatal outcomes in scheduled nonlaboring term singleton cesarean deliveries.

BACKGROUND: Most major societies do not state a specific recommendation against or in favor of routine umbilical cord gas studies sampling. OBJECTIVE: We aimed to study the correlation between abnormal umbilical cord gas studies (using 5 different definitions) and adverse neonatal outcomes in scheduled nonlaboring term singleton cesarean deliveries. STUDY DESIGN: The medical charts, surgical records, and neonatal charts of all singleton cesarean deliveries at 370/7-416/7 weeks of gestation between January 2009 and May 2018 from a single tertiary center were reviewed. The cohort of singleton cesarean deliveries was divided into those with "normal" vs "abnormal" umbilical cord gas studies with the 5 different definitions: (1) definition A: pH ≤7.15; (2) definition B: pH ≤7.15 and base excess ≤-12 mmol/L; (3) definition C: pH ≤7.1l (4) definition D: pH ≤7.1 and base excess ≤-12 mmol/L, and (5) definition E: pH <7.0 and base excess ≤-12 mmol/L. Adverse neonatal outcomes included Apgar scores at 5 minutes ≤7, neonatal sepsis, blood transfusion, phototherapy, respiratory morbidity (presence of respiratory distress syndrome, transient tachypnea of the newborn infant, mechanical ventilation, need for respiratory support, or meconium aspiration), cerebral morbidity (presence of intraventricular hemorrhage, seizures, or hypoxic-ischemic encephalopathy), necrotizing enterocolitis, or death. Composite adverse outcome was ≥1 of the aforementioned complications. RESULTS: Overall, 3001 singleton cesarean deliveries were included. The rate of abnormal umbilical cord gas studies with the use of definitions A-E was 2.6%, 0.3%, 1.2%, 0.3%, and 0.1%, respectively. The overall rate of adverse neonatal outcome for the entire cohort was 14.43% (433/3001). There was no correlation between abnormal umbilical cord gas studies and composite adverse neonatal outcome with the use of any of the definitions A-E (P=.2, P=.3, P=.2, P=.3, P=.1, respectively). The sensitivity and specificity of abnormal umbilical cord gas studies as a predictor of composite adverse neonatal outcome were calculated for each of the abnormal umbilical cord gas studies definitions; although the sensitivity was extremely low (0-2.07%), the specificity was high (97.2-99.9%) CONCLUSION: Abnormal umbilical cord gas studies are an uncommon finding in cases of singleton term singleton cesarean deliveries and do not correlate with adverse neonatal outcomes. Therefore, the clinical usefulness and cost-effectiveness of obtaining these studies routinely should be questioned.

Treatment Effect or Effective Treatment? Cardiac Compression Fraction and End-tidal Carbon Dioxide Are Higher in Patients Resuscitative Endovascular Balloon Occlusion of the Aorta Compared with Resuscitative Thoracotomy and Open-Chest Cardiac Massage.

The purpose of this study is to compare end-tidal carbon dioxide (EtCO2) during resuscitation of open-chest cardiac massage (OCCM) with aortic cross-clamp (ACC) versus receiving resuscitative endovascular balloon occlusion of the aorta (REBOA) with closed-chest compressions (CCCs). Patients who received REBOA were compared with patients receiving OCCM for traumatic arrest using continuous vital sign monitoring and videography. Thirty-three patients were enrolled in the REBOA group and 18 patients were enrolled in the OCCM group. Of the total patients, 86.3 per cent were male with a mean age of 36.2 ± 13.9 years. Ninety-four percent of patients suffered penetrating trauma in the OCCM group compared with 30.3 per cent of the REBOA group (P = <0.001). Before aortic occlusion (AO), there was no difference in initial EtCO2 values, but mean, median, peak, and final EtCO2 values were lower in OCCM (P < 0.005). During CPR after AO, the initial, mean, and median values were higher with REBOA (P = 0.015, 0.036, and 0.038). The rate of return of spontaneous circulation was higher in REBOA versus OCCM (20/33 [60.1%] vs 5/18 [33.3%]; P = 0.04), and REBOA patients survived to operative intervention more frequently (P = 0.038). REBOA patients had greater total cardiac compression fraction (CCF) before AO than OCCM (85.3 ± 12.7% vs 35.2 ± 18.6%, P < 0.0001) and after AO (88.3 ± 7.8% vs 71.9 ± 24.4%, P = 0.0052). REBOA patients have higher EtCO2 and cardiac compression fraction before and after AO compared with patients who receive OCCM.

Respiratory dysfunction in patients with chronic neck pain: What is the current evidence?

Respiratory function of patients with neck pain has not been given much consideration in usual clinical practice. The problem has however been highlighted occasionally by renown clinical scientists and recently there is a growing interest in the investigation of respiratory function in this clinical population. The aim of this review is to critically present the emerging evidence and discuss the similarities and differences observed. Although the evidence for some respiratory parameters is conflicting, it seems to be generally agreed that others such as maximal voluntary ventilation, strength of respiratory muscles, chest mechanics and partial pressure of arterial carbon dioxide are affected in patients with chronic neck pain. The effect size of the respiratory dysfunction regarding these respiratory parameters can be approximately described as moderate. These findings not only suggest a more thoughtful drug prescription, but they may lead to consideration of incorporation of respiratory assessment and treatment into routine physiotherapy practice. Indeed preliminary studies exploring the incorporation of such a treatment into usual practice have provided very promising results not only in relation to respiratory function, but also for other parameters of clinical interest. There remains however imminent need for randomized controlled trials to confirm the evidence base for such an approach.

Assessment of the interaction of hyperbaric N2, CO2, and O2 on psychomotor performance in divers.

Diving narcosis results from the complex interaction of gases, activities, and environmental conditions. We hypothesized that these interactions could be separated into their component parts. Where previous studies have tested single cognitive tasks sequentially, we varied inspired partial pressures of CO2, N2, and O2 in immersed, exercising subjects while assessing multitasking performance with the Multi-Attribute Task Battery II (MATB-II) flight simulator. Cognitive performance was tested under 20 conditions of gas partial pressure and exercise in 42 male subjects meeting U.S. Navy age and fitness profiles. Inspired nitrogen (N2) and oxygen (O2) partial pressures were 0, 4.5, and 5.6 ATA and 0.21, 1.0, and 1.22 ATA, respectively, at rest and during 100-W immersed exercise with and without 0.075-ATA CO2 Linear regression modeled the association of gas partial pressure with task performance while controlling for exercise, hypercapnic ventilatory response, dive training, video game frequency, and age. Subjects served as their own controls. Impairment of memory, attention, and planning, but not motor tasks, was associated with N2 partial pressures >4.5 ATA. Sea level O2 at 0.925 ATA partially rescued motor and memory reaction time impaired by 0.075-ATA CO2; however, at hyperbaric pressures an unexpectedly strong interaction between CO2, N2, and exercise caused incapacitating narcosis with amnesia, which was augmented by O2 Perception of narcosis was not correlated with actual scores. The relative contributions of factors associated with diving narcosis will be useful to predict the effects of gas mixtures and exercise conditions on the cognitive performance of divers. The O2 effects are consistent with O2 narcosis or enhanced O2 toxicity.

[THE STUDY OF THE EFFECTS OF ANXYOLYTIC, ANTIOXIDANT, IMMUNOCORRECTOR AND HYPERBARIC OXYGENATION ON THE DYNAMICS OF MAIN BLOOD GAS AND ELECTROLYTE INDICES AND BEHAVIORAL RESPONSE IN EXPERIMENTAL STRESS MODEL].

Experiments on the model of immobilization stress in albino mice showed that a combination of mexidol, thymogen, and hyperbaric oxygenation reduced adverse effects of diazepam on behavioral response of animals in the black-and-white chamber and elevated cross maze tests and led to optimization of the blood gas composition as manifested by increased oxygen tension, normalization of the partial pressure of carbon dioxide, and restoration of the acid-base balance and blood bicarbonate level. The proposed combined treatment can be recommended for the treatment of patients with stress-induced pathology.

[Effects of Early Goal-directed Therapy Combined with Yiqi Fumai Lyophilized Powder on P(cv-a) CO2 and S(cv)O2 in Patients with Septic Shock].

OBJECTIVE: To explore the effect of early goal-directed therapy (EGDT) combined with Yiqi Fumai Lyophilized Powder (YFLP) on central venous-arterial carbon dioxide difference [P(cv-a)CO2] and central venous oxygen saturation (S(cv)O2) in patients with septic shock. METHODS: Totally 50 patients with septic shock were assigned to the control group and the treatment group according to random digit table, 25 cases in each group. Patients in the control group received treatment according to EGDT principle. Those in the treatment group were intravenously injected with YFLP (5.2 g adding in 500 mL normal saline) additionally. Changes of P(cv-a)CO2, S(cv)O2, lactic acid, central venous pressure (CVP), mean arterial pressure (MAP), and APACHE II score were observed in the two groups before and after treatment. The 6-h success rate and 28-day mortality were also observed. RESULTS: Compared with before treatment in the same group, lactic acid and APACHE II score decreased, levels of S(cv)O2, MAP, CVP increased in the two groups after treatment (P < 0.01). P(cv-a)CO2 decreased more obviously after treatment in the treatment group, and lower than that in the control group after treatment (P < 0. 05, P < 0. 01). The 6-h success rate was 48% (12/25) in the control group and 76% (19/25) in the treatment group (P < 0.05). The 28-day mortality was 36% (9/25) in the control group and 12% (3/25) in the treatment group (P < 0.05). CONCLUSION: EGDT combined with YFLP could significantly elevate S(cv)O2, decrease P(cv-a)CO2 and mortality in patients with septic shock, and obviously improve the clinical effect.

Blood and Plasma Biochemistry Reference Intervals for Wild Juvenile American Alligators ( Alligator mississippiensis ).

: American alligators ( Alligator mississippiensis ) are one of the most studied crocodilian species in the world, yet blood and plasma biochemistry information is limited for juvenile alligators in their northern range, where individuals may be exposed to extreme abiotic and biotic stressors. We collected blood samples over a 2-yr period from 37 juvenile alligators in May, June, and July to establish reference intervals for 22 blood and plasma analytes. We observed no effect of either sex or blood collection time on any analyte investigated. However, our results indicate a significant correlation between a calculated body condition index and aspartate aminotransferase and creatine kinase. Glucose, total protein, and potassium varied significantly between sampling sessions. In addition, glucose and potassium were highly correlated between the two point-of-care devices used, although they were significantly lower with the i-STAT 1 CG8+ cartridge than with the Vetscan VS2 Avian/Reptile Rotor. The reference intervals presented herein should provide baseline data for evaluating wild juvenile alligators in the northern portion of their range.

Reduction of ischaemia-reperfusion injury in a rat lung transplantation model by low-concentration GV1001.

OBJECTIVES: Lung ischaemia-reperfusion (IR) injury is one of the major complications following lung transplantation. The novel peptide GV1001, which is derived from human telomerase reverse transcriptase, has been reported to possess both antitumour and anti-inflammatory effects. In this study, we focused on the anti-inflammatory effects of GV1001 to investigate the IR injury prevention effect of GV1001 in a rat lung transplantation model. METHODS: An orthotopic left lung transplantation rat model was established using the modified cuff technique. We applied 50 ml of normal saline (control), Perfadex (low-potassium standard dextran containing perfusion solution), Perfadex with 5 mg GV1001 (5-mg GV, low concentration) and Perfadex with 50 mg GV1001 (50-mg GV, high concentration) as both flushing and preservation solutions. The left lung was stored in the same solution as the flushing solution at 4°C for 3 h. After transplantation, the recipient rats were monitored for 3 h. Arterial blood gas analysis (ABGA), bronchoalveolar lavage (BAL) analysis, wet/dry ratio, histological analysis, apoptotic cell analysis and cytokine [tumour necrosis factor alpha (TNF-α) and interleukin 6 (IL-6)] analysis were performed to determine the reduction or prevention effect of GV1001 regarding lung IR injury. RESULTS: Compared with the control group, the neutrophil count in BAL, reperfusion oedema and cytokine (TNF-α, IL-6) levels of the transplanted lung were significantly decreased in the 5-mg GV group. Compared with the Perfadex group (16.85 ± 2.43), the neutrophil count in BAL was also significantly decreased in the 5-mg GV group (5.39 ± 0.81) (P< 0.001). In addition, the cytokine (TNF-α, IL-6) levels of the transplanted lung were also significantly decreased in the 5-mg GV group (41.99 ± 12.79, 1069.74 ± 98.48 pg/ml) compared with the Perfadex group (90.73 ± 23.87, 2051.92 ± 243.57 pg/ml) (P < 0.05 and P < 0.001, respectively). However, the 50-mg GV group showed less effect than the 5-mg GV group. CONCLUSIONS: Adding a low concentration of GV1001 to the lung preservation solution (Perfadex) provided potential protective effects against IR injury after lung transplantation in rats. Therefore, GV1001 should be considered as a promising anti-inflammatory agent for IR injury.