Blood Gas Variables Research Articles

Assessment of Postnatal Pulmonary Adaption in Bovine Neonates Using Electric Impedance Tomography (EIT).

Simple SummaryThe lungs of the neonate must oxygenate the blood and eliminate carbon dioxide at birth. Efficient gas exchange requires ventilation of the pulmonary alveoli to meet rapidly increasing oxygen demands. It is not entirely clear how quickly the different regions of the lungs become ventilated and when ventilation of all lung regions is achieved. We used electric impedance tomography (EIT) to measure lung stretch and aeration in 20 non-sedated neonatal calves born without difficulty. For EIT measurement, an electrode belt was placed around the thorax of each calf positioned in sternal recumbency immediately after birth and at various other times until 3 weeks of age to measure aeration and ventilation in different regions of the lungs. Standard EIT variables describing distribution of ventilation, respiratory rate, and several blood gas variables were determined. Most lung regions were ventilated immediately after birth. Ventilation of the ventral regions increased during the first hour, after which it decreased. Dorsal lung regions and the right lung had the greatest ventilation. The respiratory rate decreased, and the tidal impedance change as a surrogate for tidal volume increased in the first 3 weeks of life. The study showed that most regions of the lungs are ventilated immediately after birth. However, this is followed by a reduction in ventilation of ventral regions of the lungs, presumably because of gravity-driven ventral movement of residual amniotic fluid. These findings may allow identification of calves with insufficient lung expansion and ventilation after birth.Several aspects of postnatal pulmonary adaption in the bovine neonate remain unclear, particularly the dynamics and regional ventilation of the lungs. We used electric impedance tomography (EIT) to measure changes in ventilation in the first 3 weeks of life in 20 non-sedated neonatal calves born without difficulty in sternal recumbency. Arterial blood gas variables were determined in the first 24 h after birth. Immediately after birth, dorsal parts of the lungs had 4.53% ± 2.82% nondependent silent spaces (NSS), and ventral parts had 5.23% ± 2.66% dependent silent spaces (DSS). The latter increased in the first hour, presumably because of gravity-driven ventral movement of residual amniotic fluid. The remaining lung regions had good ventilation immediately after birth, and the percentage of lung regions with high ventilation increased significantly during the study period. The centre of ventilation was always dorsal to and on the right of the theoretical centre of ventilation. The right lung was responsible for a significantly larger proportion of ventilation (63.84% ± 12.74%, p < 0.00001) compared with the left lung. In the right lung, the centrodorsal lung area was the most ventilated, whereas, in the left lung, it was the centroventral area. Tidal impedance changes, serving as a surrogate for tidal volume, increased in the first 3 weeks of life (p < 0.00001). This study shows the dynamic changes in lung ventilation in the bovine neonate according to EIT measurements. The findings form a basis for the recognition of structural and functional lung disorders in neonatal calves.

Investigation of biomarkers for impending fluid overload in a feline acute haemorrhage-resuscitation model

ObjectiveTo determine biomarkers for impending fluid overload during intravenous fluid administration in a feline haemorrhage-resuscitation model. Study designRandomized crossover study. AnimalsA group of six domestic cats (mean age and weight: 21 months; 4.9 kg, respectively). MethodsThe cats underwent three treatments, 2 months apart. They were anaesthetized and instrumented to measure a range of physiological, blood gas, haematological and biochemical variables over time. Samples were taken during a health check, before haemorrhage, after haemorrhage and then at 30 minute intervals during fluid resuscitation and 24 hours later. The three treatments were: 1) control, sham haemorrhage and resuscitation; 2) lactated Ringer’s solution (LRS); and 3) 6% tetrastarch 130/0.4 (Vol) where the cats underwent a controlled haemorrhage then resuscitation by administering LRS and Vol at 60 and 20 mL kg–1 hour–1, respectively, for 120 minutes. Fluid overload was identified by nasal discharge and radiographic evidence. Biomarkers were variables that exceeded the reference interval for cats during treatment. Potential biomarkers were analysed using receiver operating characteristic curves (p < 0.05). ResultsMean ± standard deviation total blood loss was 10.2 ± 2.3, 29.3 ± 9.0 and 29.1 ± 6.3 mL kg–1 for control, LRS and Vol, respectively. The total volume of LRS and Vol administered was 120 and 40 mL kg–1, respectively. Haematocrit, albumin, magnesium, chloride-to-sodium ratio and sodium-chloride difference were identified as potential biomarkers. These variables exceeded the reference intervals from 30 minutes of resuscitation onwards. A chloride-to-sodium ratio > 0.84 was the most sensitive (90%) and specific (75%) of all potential biomarkers. Conclusions and clinical relevanceChanges in physiological variables, haematocrit and albumin were poor biomarkers of impending fluid overload compared with electrolytes. Finding the ideal biomarker to identify impending fluid overload of commonly used intravenous fluids should improve the safety of their administration in cats.

Embryotoxicity and Physiological Compensation in Chicken Embryos Exposed to Crude Oil.

Terrestrial, marine, or aquatic oil spills can directly or indirectly contaminate bird eggs. We hypothesized that chicken embryos exposed to crude oil can physiologically compensate to mitigate the potentially toxic effect of lower doses of oil. Embryos exposed to 0, 1, 3, or 5 µL of oil on embryonic days 4 and 10 were initially analyzed for mortality. All oil doses decreased day 4 embryo survival, but only the 2 highest oil doses lowered survival when applied on day 10. Thus, day 15 embryos treated with 1, 3, and 5 µL of source oil on day 10 had arterialized blood analyzed. The hematological variables hematocrit, red blood cell concentration ([RBC]), and hemoglobin concentration increased in response to 1 µL, were unchanged by 3 µL, and decreased by 5 µL of oil treatment. No changes occurred in arterialized blood gas variables (partial pressure of O2 [PO2 ], pH, bicarbonate concentration) for 1 and 3 µL embryos, but 5 µL of oil decreased PO2 and caused metabolic acidosis. Increased blood lactate in embryos treated with 3 and 5 µL of oil was correlated with decreased hematocrit and [RBC] and increased body mass, the latter likely reflecting edema. We conclude that embryos in middle development physiologically compensated for negative effects of lower doses of crude oil but that higher doses of oil were harmful to the embryos at all developmental stages. Environ Toxicol Chem 2021;40:2347-2358. © 2021 SETAC.

Predictors of inflammatory lower airway disease in cats presented to the emergency room in respiratory distress: a case-control study.

The objective of the study was to identify whether venous blood gas (VBG) variables may serve as a predictor of inflammatory lower airway disease (ILAD) in cats presenting with respiratory distress. A secondary objective of this study was to compare the diagnostic utility of patient signalment, history and physical examination findings, as compared with VBG variables. The medical records of cats presenting with respiratory distress secondary to ILAD (54 cases) and non-ILAD (121 controls) were retrospectively reviewed. No admission VBG variables were predictive of a final diagnosis of ILAD. Comparatively, multivariable analysis identified a history of a cough (P <0.001), increased respiratory rate (P = 0.001), the presence of an abdominal component to respiration (P = 0.007) and the absence of pleural effusion (P <0.01) to be independently associated with a final diagnosis of ILAD. Cats with a history of a cough and an abdominal component to respiration had 7.86 and 5.81 greater odds of being diagnosed with ILAD, respectively. Cats with pleural effusion had 7.43 lower odds of having this final diagnosis. For every 10 breaths/min increase in respiratory rate, cats had 1.48 greater odds of being diagnosed with ILAD. Cats diagnosed with ILAD had a survival rate of 94% (95% CI 84-99%) vs 61% (95% CI 51-70%) for non-ILAD controls (P <0.001). The results of this study found patient history and physical examination findings to be more useful predictors of a final diagnosis of ILAD in comparison with VBG variables at presentation. A history of a cough, an abdominal component to respiration and a lack of pleural effusion were found to be significant predictors of this diagnosis. Further investigation into the role of respiratory rate in ILAD is warranted.

Comparative study on epidural administration of dexmedetomidine, dexmedetomidine-lidocaine or lidocaine in conscious rabbits.

The aim of this study was to compare the cardiorespiratory, arterial blood gas and antinociceptive effects of dexmedetomidine (D), dexmedetomidine-lidocaine (DL) or lidocaine (L) administered epidurally on conscious rabbits. Eight six-month-old male New Zealand rabbits were randomly distributed into three treatments: D (2.5 μg/kg); DL (2.5 μg/kg; 2 mg/kg); and L (2 mg/kg). The drugs were injected epidurally via a catheter. Cardiorespiratory, arterial blood gas and antinociceptive variables were recorded before administration, 5 and 10 min after drug administration, then every 10 min until the animals presented a positive response to nociceptive stimulation of perineal dermatomes. Two animals had permanent paralysis after DL treatment due to hemorrhage and congestion with neuron necrosis in spinal cord segments. There was a reduction in mean arterial pressure in treatment L at 5 and 10 min, compared with the baseline, and in treatment DL at 10-30 min. Increases in pH were observed in treatment D at 5 and 10 min, and in DL at all the times evaluated, compared with the baseline. No alterations were observed in other blood gas or electrolyte variables. Antinociceptive effects were evaluated in the perineal, sacral and lumbar regions, and were restricted to the perineal region following D and L treatment. The antinociceptive effects following DL were greater than D and L alone in all of the regions. L and D promotes short-term antinociceptive effects for up to 15 min and, when used in combination with D, increased the duration and extent of sensory block by up to 45 min.

Dexmedetomidine-Tiletamine-Zolazepam Followed by Inhalant Anesthesia in Spectacled Bears (Tremarctos ornatus)

Background: The spectacled bear (Tremarctos ornatus) is the only bear species inhabiting South America and is classified as vulnerable according to the International Union for Conservation of Nature (IUCN) Red List. Among the few publications on the use of general anesthesia and advanced monitoring of ursids in veterinary hospital settings, little is described regarding chemical restraint, general anesthesia and monitoring of spectacled bears. This case series describes the use of a dexmedetomidine-tiletamine-zolazepam chemical restraint combination and its effects on cardiorespiratory variables and arterial blood gases observed in two spectacled bears submitted to isoflurane anesthesia for imaging and/or surgical procedures.Cases: Two female, one adult and one senile, all-term captive spectacled bears were referred to the Veterinary Medical Teaching Hospital at the Universidade Estadual Paulista - Unesp, Botucatu campus, both with a presumable history of recent trauma. After immobilization with an intramuscular (IM) administration of tiletamine-zolazepam (3.8 - 4.3 mg/kg) and dexmedetomidine (6.4 - 7.6 µg/kg), anesthesia induction was achieved by means of intravenous (IV) propofol (1 - 2 mg/kg). The patients then underwent isoflurane inhalant anesthesia and were submitted to intermittent positive-pressure ventilation through the remainder of the procedures. Initial settings of inspiratory flow rate were adjusted to obtain Ppeak of 10 cmH2O and tidal volumes (Vt) of 10 mL/kg, as well as respiratory rates (ƒR)and inspiration-to-expiration (I:E) ratio of 10 breaths/min and 1:2, respectively, and were then adjusted throughout anesthesia to maintain normocapnia (end-tidal carbon dioxide concentrations between35 and 45 mmHg). One of the individuals was chemically restrained (6.4 mg/kg of tiletamine-zolazepam and 7.7 µg/kg of dexmedetomidine) on a second anesthetic event for imaging procedures. Arterial blood gas analysis were performed with the subjects breathing room air and oxygen-enriched air. Both animals exhibited severe hypoxemia (partial pressure of oxygen [PaO2] &lt; 60 mmHg) while breathing room air (inspired oxygen fraction [FiO2] ≅ 0.21). An impaired blood oxygenation (PaO2/FiO2 &lt; 400) was still observed despite mechanical ventilation and the provision of 1.0 FiO2. Alveolar recruitment maneuvers (3 sequential mechanical sights with peak airway pressure at 20 - 30 cmH2O during 15 - 30 s each) were then performed, which resulted in improved PaO2/FiO2 ratios. All other blood gas, electrolytes and acid-base variables did not appear to be importantly altered by chemical restraint and general anesthesia.Discussion: Dexmedetomidine-tiletamine-zolazepam resulted in reliable chemical restraints and is a feasible option for immobilizing spectacled bears, though severe hypoxemia may proceed. Hypoxemia is the most commonly described complication in bear anesthesia, and was also evidenced in the current report. However, low PaO2/FiO2 ratios tend to be accompanied by hypercapnia and therefore counteracted by oxygen supplementation in bears, which was not observed in the present report. In fact, blood oxygenation only reached regular values after alveolar recruitment maneuvers, which is compatible to an atelectasis-related hypoxemia. Therefore, either inhalant anesthesia or field chemical restraint should be accompanied by advanced monitoring (cardiorespiratory variables and blood gas analysis) in until further studies address the management of hypoxemia in spectacled bear. since Advanced monitoring was of major importance for a safe outcome and an uneventful recovery in this species.Keywords: balanced anesthesia, dexmedetomidine, general anesthesia, spectacled bear, Tremarctos ornatus, wildlife.

Impact of blood storage duration on hematologic, blood gas, biochemical, and oxidative stress variables in sheep undergoing allogeneic blood transfusions.

Hemotherapy in ruminants is limited to whole blood transfusions, sometimes with stored blood for up to 42days, but little attention has been given to the effect of blood storage times and recipient responses after transfusions. We aimed to evaluate the hematologic and serum biochemical effects after allogeneic blood transfusion with either fresh or stored blood in sheep. We also sought to examine hematologic and biochemical analyte changes in the store blood. Eighteen sheep underwent a single phlebotomy to remove 40% of their blood volume. The sheep were divided into three experimental groups, G0, G15, and G35, which included six animals, each receiving 20mL/kg of either fresh blood or blood stored in citrate, phosphate, dextrose, and adenine (CPDA-1) bags for 15 and 35days, respectively. Biochemical, hematologic, coagulation, blood gas, lipid peroxidation, and oxidative stress test evaluations were performed using the blood samples gathered at T0 (before transfusion), 30minutes (T30m), 6, 12, 24, 48, 72, and 96hours (T6h-T96h), 8days (T8d), and 16days (T16d) after transfusions. Sheep exhibited increases in packed cell volumes, red blood cell counts, and total hemoglobin concentrations at T30m (P<.05). G35 animals had greater plasma hemoglobin concentrations at T12h and decreased blood pH values at T6h, characterized by slight metabolic acidemia. Regarding oxidative stress, G35 animals had decreased catalase activities from T0 at T30m, T6h, T12h, and T24h, indicating that hemolysis had occurred, which was supported by concomitant increases in bilirubin. Sheep transfused with 35-day stored blood exhibited greater hematologic, blood gas, biochemical, and oxidative alterations; however, anemic animals without comorbidities effectively reversed those alterations.

Repeat Application of Ischemic Preconditioning Improves Maximal 1,000-m Kayak Ergometer Performance in a Simulated Competition Format.

Halley, SL, Peeling, P, Brown, H, Sim, M, Mallabone, J, Dawson, B, and Binnie, MJ. Repeat application of ischemic preconditioning improves maximal 1,000-m kayak ergometer performance in a simulated competition format. J Strength Cond Res XX(X): 000-000, 2020-This study examined the effects of ischemic preconditioning (IPC) on repeat 1,000-m kayak ergometer time-trial (TT) performance, completed in a simulated competition format. Eight well-trained male kayak athletes performed 3 experimental trials, each consisting of two 1,000-m TTs separated by 80 minutes (TT 1 and TT 2). Trials included; (a) IPC (4 × 5 minutes 220 mm Hg alternating bilateral leg occlusion) 40 minutes before TT 1 only (IPC1); (b) IPC 40 minutes before TT 1 and 20 minutes before TT 2 (IPC2); and (c) no IPC (CON). Time, power, stroke rate, and expired gas variables (V[Combining Dot Above]O2 and accumulated oxygen deficit) were measured throughout each TT; blood gas variables (blood lactate, partial pressure of oxygen and blood pH) and rating of perceived exertion were measured before and after each effort. Physiological, perceptual, and physical measures were analyzed via a repeated measures analysis of variance with the level of significance set at p ≤ 0.05. There were large improvements in completion time for TT 1 in IPC1 (d = 1.24 ± 0.68, p < 0.05) and IPC2 (d = 1.53 ± 0.99, p < 0.05) versus CON. There was also a large improvement in TT 2 completion time in IPC2 versus CON (d = 1.26 ± 1.13, p = 0.03) whereas, IPC1 and CON were indifferent (d = 0.3 ± 0.54, p = 0.23). This study showed that a repeat application of IPC in a simulated competition format may offer further benefit in comparison to a single pre-exercise application of IPC.

Predictors of success and failure of non-invasive ventilation use in type-2 respiratory failure

BackgroundNon-invasive ventilation is widely used now a days in patients with hypercapnic respiratory failure. Non-invasive ventilation can be used in Intensive Care Unit setting and wards provided trained staff is there to monitor. MethodsThis was a prospective observational study of 100 adult patients who were admitted with hypercapnic respiratory failure. Demographic information such as Age, Sex were recorded. Clinical parameters like Respiratory Rate, Heart Rate, Oxygen saturation and Arterial Blood Gas variables like pH, PaCO2, HCO3 were measured at the time of admission and at 1st hour, 4 hours and 24 hours after start of non-invasive ventilation. Outcome was recorded as success and failure with Non invasive ventilation. ResultsOut of 100 patients, 76 (76%) managed successfully with non-invasive ventilation and 24 patients (24%) needed intubation and invasive mechanical ventilation in this study. Majority of patients (76%) were with clinical diagnosis of Chronic Obstructive Pulmonary Disease. Respiratory Rate and Heart Rate were significantly lower and showed significant improvement at 1st hour, 4 hours and 24 hours in patients who successfully improved with Non invasive ventilation. Oxygen saturation was found to be significantly higher among patients successfully managed with Non invasive ventilation (84.35 ± 8.55 vs 76.87 ± 7.33) as compared to patients who required intubation. pH was found to be significantly higher (7.28 ± 0.06 vs 7.23 ± 0.05) in patients showing good response to Non invasive ventilation and improvement in pH at 1st hour, 4 hours and 24 hours was observed in patients successfully managed with Non invasive ventilation. PaCO2 level was found to be significantly lower and significant improvement in PaCO2 at 1st hour, 4 hours and 24 hours was seen in patients with Non invasive ventilation success. ConclusionImprovement in clinical parameters like respiratory rate, heart rate, Oxygen saturation and improvement in ABG variables like pH, PaCO2 after 1st and 4 hours of start of Non invasive ventilation and maintaining the improvement at 24 hours are predictors of success of non-invasive ventilation in hypercapnic patients.

Endothelin receptor antagonist improves donor lung function in an ex vivo perfusion system

BackgroundA lung transplant is the last resort treatment for many patients with advanced lung disease. The majority of donated lungs come from donors following brain death (BD). The endothelin axis is upregulated in the blood and lung of the donor after BD resulting in systemic inflammation, lung damage and poor lung graft outcomes in the recipient. Tezosentan (endothelin receptor blocker) improves the pulmonary haemodynamic profile; however, it induces adverse effects on other organs at high doses. Application of ex vivo lung perfusion (EVLP) allows the development of organ-specific hormone resuscitation, to maximise and optimise the donor pool. Therefore, we investigate whether the combination of EVLP and tezosentan administration could improve the quality of donor lungs in a clinically relevant 6-h ovine model of brain stem death (BSD).MethodsAfter 6 h of BSD, lungs obtained from 12 sheep were divided into two groups, control and tezosentan-treated group, and cannulated for EVLP. The lungs were monitored for 6 h and lung perfusate and tissue samples were processed and analysed. Blood gas variables were measured in perfusate samples as well as total proteins and pro-inflammatory biomarkers, IL-6 and IL-8. Lung tissues were collected at the end of EVLP experiments for histology analysis and wet-dry weight ratio (a measure of oedema).ResultsOur results showed a significant improvement in gas exchange [elevated partial pressure of oxygen (P = 0.02) and reduced partial pressure of carbon dioxide (P = 0.03)] in tezosentan-treated lungs compared to controls. However, the lungs hematoxylin–eosin staining histology results showed minimum lung injuries and there was no difference between both control and tezosentan-treated lungs. Similarly, IL-6 and IL-8 levels in lung perfusate showed no difference between control and tezosentan-treated lungs throughout the EVLP. Histological and tissue analysis showed a non-significant reduction in wet/dry weight ratio in tezosentan-treated lung tissues (P = 0.09) when compared to control.ConclusionsThese data indicate that administration of tezosentan could improve pulmonary gas exchange during EVLP.

Effects of Positive End-Expiratory Pressure in “High Compliance” Severe Acute Respiratory Syndrome Coronavirus 2 Acute Respiratory Distress Syndrome*

Clinical observation suggests that early acute respiratory distress syndrome induced by the severe acute respiratory syndrome coronavirus 2 may be "atypical" due to a discrepancy between a relatively unaffected static respiratory system compliance and a significant hypoxemia. This would imply an "atypical" response to the positive end-expiratory pressure. Single-center, unblinded, crossover study. ICU of Bari Policlinico Academic Hospital (Italy), dedicated to care patients with confirmed diagnosis of novel coronavirus disease 2019. Eight patients with early severe acute respiratory syndrome coronavirus 2 acute respiratory distress syndrome and static respiratory compliance higher than or equal to 50 mL/cm H2O. We compared a "lower" and a "higher" positive end-expiratory pressure approach, respectively, according to the intervention arms of the acute respiratory distress syndrome network and the positive end-expiratory pressure setting in adults with acute respiratory distress syndrome studies. Patients were ventilated with the acute respiratory distress syndrome network and, subsequently, with the ExPress protocol. After 1 hour of ventilation, for each protocol, we recorded arterial blood gas, respiratory mechanics, alveolar recruitment, and hemodynamic variables. Comparisons were performed with analysis of variance for repeated measures or Friedman test as appropriate. Positive end-expiratory pressure was increased from 9 ± 3.5 to 17.7 ± 1.7 cm H2O (p < 0.01). Alveolar recruitment was 450 ± 111 mL. Static respiratory system compliance decreased from 58.3 ± 7.6 mL/cm H2O to 47.4 ± 14.5 mL/cm H2O (p = 0.018) and the "stress index" increased from 0.97 ± 0.03 to 1.22 ± 0.07 (p < 0.001). The PaO2/FIO2 ratio increased from 131 ± 22 to 207 ± 41 (p < 0.001), and the PaCO2 increased from 45.9 ± 12.7 to 49.8 ± 13.2 mm Hg (p < 0.001). The cardiac index went from 3.6 ± 0.4 to 2.9 ± 0.6 L/min/m (p = 0.01). Our data suggest that the "higher" positive end-expiratory pressure approach in patients with severe acute respiratory syndrome coronavirus 2 acute respiratory distress syndrome and high compliance improves oxygenation and lung aeration but may result in alveolar hyperinflation and hemodynamic alterations.

A special double lumen tube for use in pigs is suitable for different lung ventilation conditions

Previous studies of haemodynamic and blood gas variables during one-lung ventilation in pigs have used a double lumen tube designed for use in humans. However, because of interspecies differences in bronchial anatomy, a special design for pigs is required. In this study, we evaluated a new left-sided double lumen endobronchial tube designed for use in pigs under different lung ventilation conditions.Ten female pigs (weighing 35–40 kg) were transorally intubated, first with a single lumen tube and then with the left-sided double lumen tube for pigs, and mechanically ventilated. Haemodynamic and blood gas variables were recorded before and after intubation with the double lumen tube and before and after one-lung flooding of the left lung with saline solution. Each pig was repositioned (left lateral, to dorsal, to right lateral) every 30 min during one-lung flooding. Bronchoscopy and thoracic radiography were performed at fixed intervals.Blood gas variables during two-lung ventilation were not impaired by intubation with the double lumen endobronchial tube for pigs, compared with intubation with the single lumen tube. Haemodynamic and blood gas variables were not impaired by one-lung flooding. Complete flooding of the left lung was achieved for all pigs. Two-lung ventilation to reventilate the previously flooded lung provided complete air filling for all pigs. Use of this tube resulted in lung separation without obstruction of bronchi or resultant atelectasis. In this study, the new double lumen tube for pigs was safe for one-lung flooding and prevented fluid entry into the non-flooded lung.

Oxygen availability in a HAPE-positive and a HAPE-negative woman before and during a visit to 3480 meters

BackgroundTesting the hypoxic ventilatory response (HVR) at low-altitude helps to detect those who do not hyperventilate appropriately in hypoxia but might not necessarily predict the HVR and the risk to develop acute mountain sickness (AMS) at high altitude. However, a low HVR seems to be particularly prevalent in individuals susceptible to high-altitude pulmonary edema (HAPE+). In this short communication, we assessed differences in physiological parameters in two comparable women before and 3 hours after exposure to 3,480 meters. One woman had a (clinically diagnosed) history of high-altitude pulmonary edema (HAPE+) while the other did well at previous exposures to high altitude (HAPE-). MethodsHeart rate, blood pressure, ventilation, arterial blood gas variables, arterial haemoglobin saturation, haemoglobin concentration, arterial oxygen content and delta plasma volume were measured or calculated before and after arrival at high altitude. ResultsAt high altitude, plasma volume decreased in the HAPE- woman which in turn increased haemoglobin concentration. Ventilation was elevated in the HAPE- but not in the HAPE + woman. Arterial oxygen content fell in the HAPE + while it was preserved in the HAPE- woman. This resulted from lower peripheral oxygen saturation (-35%), lower haemoglobin concentration (-12%) and lower arterial partial pressure of oxygen (-59%) in the HAPE+. ConclusionConsiderable haemoglobin desaturation and lack of haemoconcentration were characteristics of the HAPE + woman when exposed to high altitude, while the higher arterial oxygen content in the HAPE- woman was related to both haemoconcentration and hyperventilation (and associated haemoglobin saturation).

Pharmacokinetics, sedation and hemodynamic changes following the administration of oral transmucosal detomidine gel in cats.

The aim of this study was to describe the pharmacokinetics of oral transmucosal (OTM) detomidine gel in healthy cats and assess its effects on sedation and hemodynamic variables. Eight adult cats weighing 4.12 kg ± 0.72 received 4 mg/m2 detomidine gel onto the buccal mucosa. Level of sedation, heart rate (HR), blood pressure (BP) and respiratory rate (f R) were assessed at predetermined intervals following administration. Blood samples for plasma detomidine concentrations and venous blood gas variables were collected from a medial saphenous catheter. Plasma detomidine concentrations were analyzed using ultra-high-pressure liquid chromatography with mass spectrometry detection, and pharmacokinetic estimates were obtained with compartmental methods. Data were analyzed using ANOVA and paired t-test or appropriate non-parametric tests. Sedation occurred in all cats, and was increased from baseline at 30 mins (P <0.001). Decreases in HR occurred from 15-60 mins, ranging from 140 to 165 beats per min (P <0.001). Blood glucose increased from 101 ± 12 mg/dl to 168 ± 27.3 mg/dl at 60 mins (P = 0.004). Systolic blood pressure decreased from baseline (139 ± 14.8 mmHg) to 103 ± 23.0 mmHg at 60 mins (P = 0.023). All changes abated by 120 mins. Emesis occurred in 7/7 cats within 2 mins of gel administration. Geometric mean (coefficient of variation) for clearance was 220.7 ml/min/kg (35.3 ml/min/kg), volume of distribution was 14.9 l/kg (39.9 l/kg) (both a function of bioavailability) and elimination half-life was 46.9 mins (16.0 mins). Maximum plasma concentrations of 10.5 ng/ml (35.5 ng/ml) detomidine occurred at 36.9 mins (21.5 mins). OTM detomidine gel produced moderate sedation with minimal undesirable side effects in healthy cats, although emesis occurred in all cats. The pharmacokinetic profile supports short-term, minimally invasive sedation in this species. Further studies are warranted to assess its safety and feasibility for use in debilitated cats, or prior to general anesthesia.

Evaluation of hematologic, biochemical, and blood gas variables in stored canine packed red blood cells, and the impact of storage time on blood recipients.

Canine packed red blood cells (pRBCs) can be stored under refrigeration for several days; however, cellular metabolism remains active inside the units, thus producing substances that affect their quality. We aimed to evaluate hematologic, biochemical, and blood gas variable alterations that occur in canine pRBCs during storage, and their effects on recipient clinicopathologic parameters. The study was conducted in two phases. In phase I, 15 pRBC units containing CPDA-1 were stored for 28days; samples were collected weekly from the units of days 0 to 28 to measure the packed cell volume (PCV), pH, partial pressure carbon dioxide (PCO2 ), partial pressure oxygen (PO2 ), concentrations of lactate and potassium, and the percent hemolysis. In phase II, another 22 canine pRBC units stored for different time periods (maximum of 21days) were transfused, and the recipients were evaluated before and after transfusion for changes in clinical parameters (heart rate, respiratory rate, systolic arterial pressure, and rectal temperature) and hematologic variables (PCV, lactate and potassium concentrations, pH, PCO2 , the ratio of arterial oxygen partial pressure to fractional inspired oxygen [PO2 /FiO2 ] ratio, oxygen saturation [SaO2 ], base excess, and bicarbonate [HCO3 ]). In the pRBC units, the PCV increased from 70% to 78.33%, the lactate concentration increased 627%, the potassium concentration increased 183%, the percent hemolysis reached 0.69%, and the pH decreased 9% after 28days. However, the dogs who received transfusions were not negatively affected. There was a significant increase in PCVs, and a significant decrease in heart rates. Canine pRBCs undergo hematologic, blood gas, and biochemical alterations during storage; however, the transfusion of pRBCs stored for up to 21days increased PCVs without causing harm to the dogs.

Lung injury in brain ischemia/reperfusion is exacerbated by mechanical ventilation with moderate tidal volume in rats.

Ischemic stroke is one of the most frequent causes of injury in the central nervous system which may lead to multiorgan dysfunction, including in the lung. The aim of this study was to investigate whether brain ischemia/reperfusion with or without mechanical ventilation leads to lung injury. Male Sprague-Dawley rats were assigned to four groups: Sham, 1-h brain ischemia (MCAO)/24-h reperfusion (I/R), mechanical ventilation with moderate tidal volume (MTV), and I/R+MTV. The pulmonary capillary permeability (Kfc) was measured in the isolated perfused lung. Mean arterial blood pressure (MAP), heart rate (HR), blood-gas variables, histopathological parameters, lung glutathione peroxidase, and TNF-α were measured. Kfc in the I/R, MTV, and I/R+MTV groups were higher than that in the Sham group. In the I/R, MTV, and I/R+MTV groups, arterial partial pressures of oxygen and the arterial partial pressure of oxygen/fraction of inspired oxygen ratios were lower, whereas arterial partial pressures of carbon dioxide were higher than those in the Sham group. The histopathological score in the I/R group was more than that in the Sham group, and in the MTV and I/R+MTV groups were higher than those in the Sham and I/R groups. Furthermore, there were stepwise rises in TNF-α in the I/R, MTV, and I/R+MTV groups, respectively. There was no significant difference in MAP between groups. However, HR in the MTV group was higher than that in the Sham group. Brain ischemia/reperfusion leads to pulmonary capillary endothelial damage and the impairment of gas exchange in the alveolar-capillary barrier, which is exacerbated by mechanical ventilation with moderate tidal volume partially linked to inflammatory reactions.

Prognostic value of venous blood analysis at the start of CPR in non-traumatic out-of-hospital cardiac arrest: association with ROSC and the neurological outcome

BackgroundThe knowledge of new prognostic factors in out-of-hospital cardiac arrest (OHCA) that can be evaluated since the beginning of cardiopulmonary resuscitation (CPR) manoeuvres could be helpful in the decision-making process of prehospital care. We aim to identify metabolic variables at the start of advanced CPR at the scene that may be associated with two main outcomes of CPR (recovery of spontaneous circulation (ROSC) and neurological outcome).MethodsProspective observational study of all non-traumatic OHCA in patients older than 17 years assisted by emergency medical services (EMS), with doctor and nurse on board, between January 2012 and December 2017. Venous blood gases were sampled upon initially obtaining venous access to determine the initial values of pH, pCO2, HCO3−, base excess (BE), Na+, K+, Ca2+ and lactate. ROSC upon arrival at the hospital and neurological status 30 days later (Cerebral Performance Categories (CPC) scale) were recorded.ResultsWe included 1552 patients with OHCA with blood test data in a 6-year period. ROSC was achieved in 906 cases (58.4%), and good neurological recovery at 30 days (CPC I-II) occurred in 383 cases (24.68%). In multivariate analysis, we found a significant relationship between non-recovery of spontaneous circulation (no-ROSC) and low pH levels (adjusted odds ratio (OR) 0.03 (0.002–0.59), p = 0.020), high pCO2 levels (adjusted OR 1.03 [1.01–1.05], p = 0.008) and high potassium levels (adjusted OR 2.28 [1.43–3.61], p = 0.008). Poor neurological outcomes were associated with low pH levels (adjusted OR 0.06 [0.02–0.18], p < 0.001), high pCO2 (adjusted OR 1.05 [1.03–1.08], p < 0.001), low HCO3− (adjusted OR 0.97 [0.94–0.999], p = 0.044), low BE (adjusted OR 0.96 [0.93–0.98], p < 0.001) and high potassium levels (adjusted OR 1.37 [1.16–1.60], p < 0.001).ConclusionThere is a significant relationship between severe alterations of venous blood-gas variables and potassium at the start of CPR of non-traumatic OHCA and low-ROSC rate and neurological prognosis.

Assessment of the benefits of head-up preoxygenation using near-infrared spectroscopy with pulse oximetry in a swine model.

Compared with supine positioning, head-up positioning improves preoxygenation and prolongs the time to oxygen desaturation. We reevaluated benefits of head-up positioning using near-infrared spectroscopy (NIRS) with pulse oximetry in a pig model. Six pigs (mean ± SD weight: 25.3 ± 0.6 kg) were anesthetized with isoflurane and evaluated in four positions—supine, head-up, head-down, head-up to supine—just before apnea (positions’ order after “supine” was randomized). In each position, after 5 min of preoxygenation with 100% oxygen, apnea was induced and the time to SpO2 < 70% measured. Hemodynamic and blood-gas variables and the cerebral tissue oxygenation index (TOI) were evaluated using NIRS and recorded. Hypovolemia was induced by collecting 600 mL blood. Apnea experiment was performed again in each position. The times (seconds) ± SD to SpO2 < 70% were 108 ± 13 (supine), 138 ± 15 (head-up; P < 0.0001 vs all other positions); 101 ± 12 (head-down) and 106 ± 15 (head-up to supine) during normovolemia, and 110 ± 29, 120 ± 7 (not significant vs all other positions), 101 ± 16, and 106 ± 11, respectively, during hypovolemia. Although the TOI was not associated with the positions during normovolemia, the head-up position during hypovolemia decreased TOI from 62% ± 6% (supine) to 50% ± 9% (head-up; P = 0.0019) before preoxygenation, and it remained low during apnea. The head-up position improves preoxygenation, but repositioning to supine negates the benefits. Head-up positioning during evident hypovolemia should be avoided because the cerebral oxygenation could decrease.

Effects of midazolam and nitrous oxide on the minimum anesthetic concentration of isoflurane in the ball python (Python regius)

ObjectiveTo evaluate the effects of midazolam and nitrous oxide (N2O) on the minimum anesthetic concentration of isoflurane (MACISO) in ball pythons. Study designProspective, crossover, randomized, semi-blinded study. AnimalsA total of nine healthy adult female ball pythons (Python regius) weighing 2.76 ± 0.73 kg. MethodsIn each snake, three protocols were evaluated with 2 week washouts: treatment MID–O2, midazolam (1 mg kg−1) administered intramuscularly (IM) and anesthesia induced with isoflurane–oxygen; treatment SAL–O2, saline (0.2 mL kg−1) IM and anesthesia with isoflurane–oxygen; and treatment SAL–N2O, saline IM and anesthesia with isoflurane and 50% nitrous oxide (N2O):50% oxygen. In each treatment, isoflurane was administered by face mask immediately after premedication. Snakes were endotracheally intubated and inspired and end-tidal isoflurane concentrations were monitored. The study design followed a standard bracketing technique, and the MACISO was determined using logistic regression. Electrical stimulation using a Grass stimulator connected to the base of the tail (50 V, 50 Hz, 6.5 ms pulse−1) was used as the supramaximal stimulus. Blood-gas analysis was performed on cardiac blood collected immediately following intubation and after the last stimulation. Blood-gas variables were compared over time and between treatments using linear mixed models. ResultsMACISO at a body temperature of 30.1 ± 0.4 °C was 1.11% (95% confidence interval, 0.94–1.28%) in SAL–O2 and was significantly decreased to 0.48% (0.29–0.67%) in MID–O2 (p < 0.001) and to 0.92% (0.74–1.09%) in SAL–N2O (p = 0.016). PO2 was significantly lower in MID–O2 and SAL–N2O than in SAL–O2. Conclusions and clinical relevanceMidazolam significantly decreased the MACISO by 57% in ball pythons, whereas addition of N2O resulted in a modest, although significant, decrease (17%). MACISO in ball pythons was lower than those previously reported in reptiles.

Response of juvenile Lophiosilurus alexandri to osmotic and thermic shock.

The objective of the present study was to evaluate the physiological responses of juvenile Lophiosilurus alexandri submitted to osmotic and thermic shock. Thirty juveniles were used for each test, of which 10 were not subjected to stress and remained in normal conditions (fresh water at 28.0°C). The others were submitted to stress shock (saline water of 10.0g of salt/L or water cooled to 18.0°C). Blood samples were taken at 0h (no exposure to the stress factor) and 1h and 24h after the tests. At 24h, the survivorship was 100% in both tests. In both the osmotic and thermic shock tests, cortisol and glucose levels were higher at 1h but then decreased after 24h. Lactate dehydrogenase showed differences in the temperature test, but there was no difference between 1 and 24h after exposure to osmotic shock (P > 0.05). The difference was recorded in blood gas variables (pH, PvCO2, PvO2, hemoglobin, sO2, BE, tCO2, HCO3-, and stHCO3-) and electrolytes (Na+, Ca++, nCa++, and K+) in both experiments. With regard to hematology and blood biochemistry, exposure to thermal shock did not affect (P > 0.05) ALP, total plasma protein, hematocrit, and ALT and AST at 1h and 24h. ALP and total protein in the blood of fish submitted to the osmotic shock were lowest (P < 0.05) at 24h. Leukocyte and erythrocyte counts exhibited differences after osmotic shock, in contrast to erythrocyte counts of the temperature test, which did not change in 24h (P > 0.05). Juveniles of L. alexandri were able to reestablish the main indicators of stress (cortisol, glucose), while the others (hematological, biochemical, and gasometric) varied in compensation for normal physiological reestablishment.