Improvement In Arterial Oxygenation Research Articles

Virological and clinical features of acute respiratory failure associated with COVID-19 in pregnancy: a case-control study

Objective: Pregnancy is a risk factor for acute respiratory failure (ARF) following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. We hypothesised that SARS-CoV-2 viral load in the respiratory tract might be higher in pregnant intensive care unit (ICU) patients with ARF than in non-pregnant ICU patients with ARF as a consequence of immunological adaptation during pregnancy. Design: Single-centre, retrospective observational case-control study. Setting: Adult level 3 ICU in a French university hospital. Participants: Eligible participants were adults with ARF associated with coronavirus disease 2019 (COVID-19) pneumonia. Main outcome measure: The primary endpoint of the study was viral load in pregnant and non-pregnant patients. Results: 251 patients were included in the study, including 17 pregnant patients. Median gestational age at ICU admission amounted to 28 + 3/7 weeks (interquartile range [IQR], 26 + 1/7 to 31 + 5/7 weeks). Twelve patients (71%) had an emergency caesarean delivery due to maternal respiratory failure. Pregnancy was independently associated with higher viral load (-4.6 ± 1.9 cycle threshold; P < 0.05). No clustering or over-represented mutations were noted regarding SARS-CoV-2 sequences of pregnant women. Emergency caesarean delivery was independently associated with a modest but significant improvement in arterial oxygenation, amounting to 32 ± 12 mmHg in patients needing invasive mechanical ventilation. ICU mortality was significantly lower in pregnant patients (0 v 35%; P < 0.05). Age, Simplified Acute Physiology Score (SAPS) II score, and acute respiratory distress syndrome were independent risk factors for ICU mortality, while pregnancy status and virological variables were not. Conclusions: Viral load was substantially higher in pregnant ICU patients with COVID-19 and ARF compared with non-pregnant ICU patients with COVID-19 and ARF. Pregnancy was not independently associated with ICU mortality after adjustment for age and disease severity.

Physiological benefits of lung recruitment in the semi-lateral position after laparoscopic surgery: a randomized controlled study

We evaluated the physiological benefits of performing lung recruitment maneuver (LRM) in the semi-lateral position compared in the supine position. Seventy-nine patients undergoing laparoscopic prostatectomy were randomly assigned to either the supine or semi-lateral group according to body position during the LRM. At the end of surgery, LRM (35 cmH2O for 20 s) was performed twice in the assigned posture. The primary outcome was the maximal decrease in systolic arterial pressure during LRM. Secondary outcomes were changes in PaO2/FiO2 and the regional lung volume distribution after LRM. The decrease in systolic arterial pressure during the LRM was significantly higher in the supine group than in the semi-lateral group (mean ± standard deviation, [−] 27.6 ± 14.6% vs. [−] 18.6 ± 9.9%, P = 0.001). Improvement in PaO2/FiO2 ratio after the LRM was evident in both groups but was more prominent in the semi-lateral group than in the supine group (median [interquartile range], 39.3% [20.2, 63.6] vs. 18.2% [8.4, 29.2], P = 0.001). Among the horizontal lung divisions, regional lung volume in the most dependent portion (the dorsal division) was significantly increased after the LRM only in the semi-lateral group (P = 0.024). Performing lung recruitment in a semi-lateral position protected against hemodynamic deterioration during the LRM and increased regional lung ventilation in the dependent portion of the lung, leading to an improvement in arterial oxygenation after laparoscopic procedures.Trial registration Clinical Research Information Service (https://cris.nih.go.kr/). Identifier: KCT0003756.

Therapeutic benefits of proning to improve pulmonary gas exchange in severe respiratory failure: focus on fundamentals of physiology.

New Findings What is the topic of this review? The use of proning for improving pulmonary gas exchange in critically ill patients. What advances does it highlight? Proning places the lung in its ‘natural’ posture, and thus optimises the ventilation‐perfusion distribution, which enables lung protective ventilation and the alleviation of potentially life‐threatening hypoxaemia in COVID‐19 and other types of critical illness with respiratory failure. The survival benefit of proning patients with acute respiratory distress syndrome (ARDS) is well established and has recently been found to improve pulmonary gas exchange in patients with COVID‐19‐associated ARDS (CARDS). This review outlines the physiological implications of transitioning from supine to prone on alveolar ventilation‐perfusion (V˙A--Q˙) relationships during spontaneous breathing and during general anaesthesia in the healthy state, as well as during invasive mechanical ventilation in patients with ARDS and CARDS. Spontaneously breathing, awake healthy individuals maintain a small vertical (ventral‐to‐dorsal) V˙A/Q˙ ratio gradient in the supine position, which is largely neutralised in the prone position, mainly through redistribution of perfusion. In anaesthetised and mechanically ventilated healthy individuals, a vertical V˙A/Q˙ ratio gradient is present in both postures, but with better V˙A--Q˙ matching in the prone position. In ARDS and CARDS, the vertical V˙A/Q˙ ratio gradient in the supine position becomes larger, with intrapulmonary shunting in gravitationally dependent lung regions due to compression atelectasis of the dorsal lung. This is counteracted by proning, mainly through a more homogeneous distribution of ventilation combined with a largely unaffected high perfusion dorsally, and a consequent substantial improvement in arterial oxygenation. The data regarding proning as a therapy in patients with CARDS is still limited and whether the associated improvement in arterial oxygenation translates to a survival benefit remains unknown. Proning is nonetheless an attractive and lung protective manoeuvre with the potential benefit of improving life‐threatening hypoxaemia in patients with ARDS and CARDS.

Prone Positioning in Spontaneously Breathing Subjects With Moderate or Severe ARDS During Invasive Ventilation.

Prone positioning (PP) during invasive mechanical ventilation improves outcomes of patients with severe ARDS. Recent studies suggest that PP in spontaneously breathing, nonintubated patients with acute respiratory failure is well tolerated and improves oxygenation. However, little is known regarding patient triggered ventilation in intubated patients with ARDS undergoing PP. We conducted a retrospective review of our experience with placing patients in the prone position in 2 cohorts of subjects with moderate and severe ARDS (ie, one cohort with ARDS related to COVID-19, the other with ARDS unrelated to COVID-19), many of whom were receiving pressure support ventilation (PSV). We conducted a retrospective analysis in a single 22-bed mixed ICU. The subjects included in the analysis were ≥ 18 y old, met the Berlin definition for moderate or severe ARDS (whether related COVID-19 or not), and underwent PP during invasive ventilation. 39 subjects were included in the analysis: 20 subjects had ARDS related to COVID-19, while 19 had ARDS related to other etiologies. A total of 113 PP episodes were analyzed: 84 during PSV and 29 during volume control continuous mandatory ventilation. PP during PSV was well tolerated and was effective in improving arterial oxygenation (ie, an increase of median [Formula: see text] from 100 mm Hg [interquartile range 75-120] before PP to 135 mm Hg [interquartile range 111-161] at the end of the PP session, P < .0001). No significant difference between continuous mandatory ventilation and PSV was noted regarding arterial oxygenation during PP. Compared with continuous mandatory ventilation mode, PP during PSV was associated with a significant decrease in the use of neuromuscular blocking agents (4% vs 69% of subjects, P < .001), while sedative requirements remained unchanged. In a retrospective analysis of consecutive intubated subjects with moderate or severe ARDS, related or not to COVID-19, spontaneous breathing during PP was well tolerated and achieved significant improvement in arterial oxygenation.

Cardiovascular function, pulmonary gas exchange and tissue oxygenation in isoflurane-anesthetized, mechanically ventilated Beagle dogs with four levels of positive end-expiratory pressure

ObjectivesTo compare pulmonary gas exchange, tissue oxygenation and cardiovascular effects of four levels of end-expiratory pressure: no positive end-expiratory pressure (ZEEP), positive end-expiratory pressure (PEEP) of maximal respiratory system compliance (PEEPmaxCrs), PEEPmaxCrs + 2 cmH2O (PEEPmaxCrs+2), PEEPmaxCrs + 4 cmH2O (PEEPmaxCrs+4), in isoflurane-anesthetized dogs. Study designProspective randomized crossover study. AnimalsA total of seven healthy male Beagle dogs, aged 1 year and weighing 10.2 ± 0.7 kg (mean ± standard deviation). MethodsThe dogs were administered acepromazine and anesthesia was induced with propofol and maintained with isoflurane. Ventilation was controlled for 4 hours with ZEEP, PEEPmaxCrs, PEEPmaxCrs+2 or PEEPmaxCrs+4. Cardiovascular, pulmonary gas exchange and tissue oxygenation data were evaluated at 5, 60, 120, 180 and 240 minutes of ventilation and compared using a mixed-model anova followed by Bonferroni test. p < 0.05 was considered significant. ResultsCardiac index (CI) and mean arterial pressure (MAP) were lower in all PEEP treatments at 5 minutes when compared with ZEEP. CI persisted lower throughout the 4 hours only in PEEPmaxCrs+4 with the lowest CI at 5 minutes (2.15 ± 0.70 versus 3.45 ± 0.94 L minute–1 m–2). At 180 and 240 minutes, MAP was lower in PEEPmaxCrs+4 than in PEEPmaxCrs, with the lowest value at 180 minutes (58 ± 7 versus 67 ± 7 mmHg). Oxygen delivery index (DO2I) was lower in PEEPmaxCrs+4 than in ZEEP at 5, 60, 120 and 180 minutes. Venous admixture was not different among treatments. Conclusion and clinical relevanceThe use of PEEP caused a transient decrease in MAP and CI in lung-healthy dogs anesthetized with isoflurane, which improved after 60 minutes of ventilation in all levels of PEEP except PEEPmaxCrs+4. A clinically significant improvement in arterial oxygenation and DO2I was not observed with PEEPmaxCrs and PEEPmaxCrs+2 in comparison with ZEEP, whereas PEEPmaxCrs+4 decreased DO2I.

FX06-COVID: Improvement of arterial oxygenation in intensive care patients with a severe course of COVID-19

FX06-COVID: Improvement of arterial oxygenation in intensive care patients with a severe course of COVID-19

Improvement of arterial oxygenation using the double trunk mask above low flow nasal cannula: a pilot study

Improvement of arterial oxygenation using the double trunk mask above low flow nasal cannula: a pilot study

Goal-directed dehydration therapy in sepsis and acute respiratory distress syndrome guided by volumetric hemodynamic monitoring

The aim of our study was to improve results of treatment of critically ill patients with sepsis and acute respiratory distress syndrome (ARDS) using the goal-directed dehydration therapy (DT).Sixty adult patients with sepsis and ARDS receiving mechanical ventilation for at least 24 hours were enrolled into a prospective randomized study. The patients were randomized into groups of dehydration guided either by extravascular (group of extravascular lung water index ‒ EVLWI,n= 30) or intravascular (group of global end-diastolic volume index ‒ GEDVI,n= 30) compartment. Dehydration was performed over 48 hours by administering diuretics or controlled extracorporeal ultrafiltration. We measured ventilation parameters, blood gases, and parameters of volumetric monitoring. The baseline characteristics of the patients did not differ between the groups. By 48 hours, the target fluid balance was achieved in both groups. In the EVLWI group at 48 hours, we found reduction of EVLWI by 15.4% (p&lt; 0.001) and increase in PaO2/FiO2by 23.3% as compared with baseline (p&lt; 0.001). In parallel, we observed decrease in creatinine and urea (p&lt; 0.05). In the GEDVI group, PaO2/FiO2 rose by 12.5% (p = 0.021), whereas EVLWI remained unchanged (p= 0.4). Maximal decrease in EVLWI and improvement of PaO2/FiO2 were achieved in direct ARDS.Thus, in patients with sepsis and ARDS the de-escalation goal-directed therapy resulted in the improvement of arterial oxygenation and organ function. The efficacy of dehydration was increased in direct ARDS. The extravascular compartment dehydration algorithm attenuated pulmonary edema and acute kidney injury more efficiently. Therefore, sepsis-induced ARDS may require personalized therapeutic approach.

Effects of acute hemorrhage on intrapulmonary shunt in a pig model of acute respiratory distress-like syndrome.

BackgroundIn acute respiratory distress syndrome (ARDS), gas exchange and respiratory system mechanics (compliance) are severely impaired. Besides ventilatory parameters, the degree of respiratory abnormality can be influenced by the circulatory state. This study investigated the influence of acute hypovolemia on the respiratory system.MethodsWe performed a secondary analysis of a previous study including 8 pigs with ARDS-like syndrome induced by lung lavage and surfactant depletion method (ARDS group) and 10 mechanically ventilated pigs with no intervention (CTRL group). Animals of both groups were subjected to hemorrhage and retransfusion successively. We reanalyzed the effect of acute blood volume variations on intrapulmonary shunt (shunt), arterial oxygenation (PaO2:FiO2), global oxygen delivery (DO2) and respiratory system compliance (Crs).ResultsIn the ARDS group, after hemorrhage, shunt decreased (−28 +/− 3.5 % (p < 0.001)), respiratory system compliance (Crs) increased (+5.1 +/− 1.0 ml/cm H2O (p < 0.001)) moreover, there was a concurrent increase in PaO2:FiO2 (+113 +/− 19.1 mmHg; p < 0.001) but this did not prevent a reduction in DO2 (−317 +/− 49.8 ml/min; p < 0.001). Following retransfusion, shunt and Crs return towards pre-hemorrhage values. Similar changes, but of smaller magnitude were observed in the CTRL group, except that no significant changes in oxygenation occurred.ConclusionsThe present analysis suggests that an acute decrease in blood volume results in a decrease in shunt with a parallel improvement in arterial oxygenation and an increase in Crs during ARDS-like syndrome. Our results strengthen the importance to integrate the circulatory condition in the analysis of the state of the respiratory system. However, the translation of this physiological model in a clinical perspective is not straightforward because our model of acute and severe hemorrhage is not strictly equivalent to a progressive hypovolemia, as could be obtained in ICU by diuretic. Furthermore, the present model does not consider the impact of blood loss induced decrease of DO2 on other vital organs function.Trial registration‘Not applicable’.

Venovenous Extracorporeal Membrane Oxygenation for Acute Respiratory Distress Syndrome in Adults: Prognostic Factors for Outcomes.

Despite a therapeutic option for severe acute respiratory distress syndrome (ARDS), the survival benefit of venovenous extracorporeal membrane oxygenation (VV-ECMO) is still controversial in adults. This study was aimed at investigating the prognostic factors for ECMO-treated ARDS in adult patients.From 2012 to 2015, 49 patients (median age: 57 years) received VV-ECMO in our institution and were included in this retrospective study. The indication of VV-ECMO was a severe hypoxemia (PaO2/FiO2 ratio <70 mmHg) under mechanical ventilation (MV) with a peak inspiratory pressure (PIP) >35 cmH2O and a FiO2 >0.8. To decrease the impact of pulmonary injuries associated with the high-pressure ventilation, the settings of MV on VV-ECMO were downgraded according to our protocol. Outcomes of this study were death on VV-ECMO and death in hospital. Important demographic and clinical data during the treatment were collected for outcome analyses.All patients experienced significant improvements in arterial oxygenation on VV-ECMO. Twenty-four hours after initiation of VV-ECMO, the median PaO2/FiO2 ratio increased from 58 to 172 mmHg (P < 0.001) and the median SaO2 increased from 86% to 97% (P < 0.001). In the meantime, the MV settings were also effectively downgraded. The median PIP decreased from 35 to 29 cmH2O (P < 0.001) and the median tidal volume decreased from 7 to 5 ml/kg/min (P < 0.001). Twelve patients died during the treatment of VV-ECMO and 21 patients died before hospital discharge. Among all of the pre-ECMO variables, the pre-ECMO pulmonary dynamic compliance (PCdyn) <20 mL/cmH2O was identified to be the prognostic factor of death on VV-ECMO (odds ratio [OR]: 6, 95% confidence interval [CI]: 1–35, P = 0.03), and the pre-ECMO duration of MV >90 hours was the prognostic factor of death before hospital discharge (OR: 7, 95% CI: 1–29, P = 0.01).VV-ECMO was a useful salvage therapy for severe ARDS in adults. However, the value of PCdyn and the duration of MV before intervention with VV-ECMO may significantly affect the patients’ outcomes.

Effect of Manual Hyperinflation on Arterial Oxygenation in Paediatric Patients with Upper Lobe Collapse after Cardiac Surgery

Lung hyperinflation is a technique used by physiotherapists to mobilize and remove excess bronchial secretions, reinflate areas of pulmonary collapse and improve oxygenation. To assess the efficacy of manual hyperinflation in improving arterial oxygenation (PaO2) of paediatric patients with upper lobe lung collapse after cardiac surgery. 18 paediatric patients who had undergone heart surgery and having upper lobe collapse in the post-op ventilation period underwent Manual Hyperinflation (MH). Parameters in cluded arterial oxygen tension (PaO2) value in ABG analysis, clinical findings such as collapsed upper lung lobe in chest radiograph and air entry in auscultation were collected before and 30 min post MH session and documented. The patients were treated with manual hyperinflation delivered using a pediatric AMBU bag with pressure of about 40 cm H 2O. Four sets of eight bag compressions with inflation rate of 10 breaths per minute were delivered during each manual hyperinflation. The result showed that there was a significant improvement in arterial oxygenation (PaO 2) by administering manual hyperinflation therapy for the upper lobe col lapse in post-op ventilated paediatric patients. In this study, it is evident that manual hyperinflation is an effective technique in management of Lung collapse (upper lobe) in post-op pediatric patients. This clearly demonstrates that further research in this area is warranted.

Lung recruitment strategies

Mechanical ventilation in newborns, children and adults leads to lung injury and has been shown to induce the formation of proteinaceous lung oedema causing epithelial disruption and resulting in changes in lung perfusion. Lung injury leads to reduced compliance, worsening of shunt fraction and an inflammatory response that results from high end-inspiratory transpulmonary pressures (Ptp) and inadequate End Expiratory Lung Volume (EELV). Lung injury results if a lung is ventilated from collapsed state with each ventilator cycle. Thus the first concept of treatment in acute hypoxic respiratory failure is: “Open collapsed lung units and keep them open without overdistending them”. The open lung is one in which there is little or no atelectasis and an optimal gas exchange. Lung recruitment strategies transiently increase Ptp to reopen the alveolar units not aerated or poorly aerated but recruitable. Lung recruitment maneuvers may restore EELV resulting in more stable alveoli, and reduce shear stress associated with the alveolar cyclic opening and closing. Lung recruitment can be performed in several ways: in delivery room with a T-piece device, in the NICU setting by using a conventional or high frequency oscillation (HFO) ventilator, and is commonly achieved by increase of end-expiratory lung volume with positive end expiratory pressure (PEEP) or end inspiratory lung volume by inspiratory holds or sustained inflation. Recruitment during both, HFO and CMV (Conventional Mechanical Ventilation), follows similar concepts when using small tidal volume ventilation but is easier to achieve at bedside during HFO. The Sustained Inflation maneuver (SI) applies a high pressure to the lung for a short period (30 sec) before returning to previous mean airway pressures. This volume recruitment strategy has been shown to be as protective as high frequency oscillatory ventilation (HFO) at similar lung volumes. Infants treated with a SI in delivery room had improved short-term respiratory outcomes (reduced need of tracheal intubation and mechanical ventilation), but major outcomes (BPD Bronchopulmonary dysplasia- and/or death) were not improved. Recent reports describe improvements in arterial oxygenation with the use of recruitment maneuvers during CMV and/or HFO. However, the impact of these strategies on patient important outcomes such as survival is still unclear. Further clinical studies are needed to evaluate the efficacy of SI, including selection of patients, setting of SI maneuver in terms of duration and peak pressure, timing of surfactant administration. Further studies are also needed to elucidate the impact of recruitment maneuvers during mechanical ventilation, including survival and BPD.

Improvement of arterial oxygenation in free-ranging moose (Alces alces) immobilized with etorphine-acepromazine-xylazine

BackgroundThe effect of intranasal oxygen and/or early reversal of xylazine with atipamezole on arterial oxygenation in free-ranging moose (Alces alces) immobilized with etorphine-acepromazine-xylazine with a cross-sectional clinical study on 33 adult moose was evaluated.Moose were darted from a helicopter with 3.37 mg etorphine, 15 mg acepromazine and 75 mg xylazine. Intranasal oxygen at a flow rate of 4 L/min and/or early reversal of xylazine with 7.5 mg atipamezole to improve oxygenation was evaluated, using four treatment regimens; intranasal oxygen (n = 10), atipamezole intramuscularly (n = 6), atipamezole intravenously (n = 10), or a combination of atipamezole intravenously and intranasal oxygen (n = 7). Arterial blood was collected 7–30 minutes (min) after darting, and again 15 min after institution of treatment and immediately analyzed using an i-STAT®1 Portable Clinical Analyzer.ResultsBefore treatment the mean ± SD (range) partial pressure of arterial oxygen (PaO2) was 62 ± 17 (26–99) mmHg. Twenty-six animals had a PaO2 < 80 mmHg. Ten had a PaO2 of 40–60 mmHg and three animals had a PaO2 < 40 mmHg. Intranasal oxygen and intravenous administration of atipamezole significantly increased the mean PaO2, as did the combination of the two. In contrast, atipamezole administered intramuscularly at the evaluated dose had no significant effect on arterial oxygenation.ConclusionsThis study shows that intranasal oxygen effectively improved arterial oxygenation in immobilized moose, and that early intravenous reversal of the sedative component, in this case xylazine, in an opioid-based immobilization drug-protocol significantly improves arterial oxygenation.

THE SUCCESSFUL TREATMENT OF A PERIPHERAL VENO-VENOUS EXTRACORPOREAL MEMBRANE OXYGENATION FOR SEVERE ACUTE RESPIRATORY FAILURE IN THE EARLY PERIOD AFTER ADULT LIVER TRANSPLANTATION

Aim: of our clinical study was to present own experience of veno-venous extracorporeal membrane oxygenation (VV ECMO) for the treatment of an adult patient (female, 28 yrs, 150 cm, 35 kg) with acute respiratory distress syndrome (ARDS) in the early period after liver transplantation against satisfactory liver graft function. Materials and methods. Double-lumen cannula 22 F was placed percutaneously in the right internal jugular vein. The ext- racorporeal contour reduced in length and the polymethylpeptene oxygenator (priming volume 175 ml) were also. Results. In 1 hour after the beginning of VV ECMO, we registered the noted improvement of arterial blood gas and acid-base balance (regress of respiratory acidosis, improvement of arterial oxygenation) which allowed us to use the «protective» mode of mechanical ventilation. Improvement of gas exchange and regress of clinical and radiological manifestations of ARDS allowed for VV ECMO weaning and decannulation on day 7. The patient was discharged from ICU and then from our Centre to a homestay respectively on the 9 th and 16 th day after VV ECMO weaning with the satisfactory liver graft and lungs function. Conclusion. VV ECMO can be successfully applied to correct the life-threatening acute respiratory failure in the early period after liver transplantation.

Effect of nitric oxide inhalation on gas exchange in acute severe pneumonia

Inhaled nitric oxide (NO) causes selective pulmonary vasodilatation and may improve gas exchange. The study was aimed to evaluate the acute effects of inhaled NO on pulmonary gas exchange in severe unilateral pneumonia, where hypoxemia results from increased intrapulmonary shunt. We studied 8 patients without preexisting lung disease (59±18 yr; 4M/4F) with early unilateral severe pneumonia and respiratory failure. Pulmonary and systemic hemodynamics and gas exchange, including ventilation–perfusion (V;A/Q;) distributions, were measured at baseline and while breathing 5 and 40 parts per million (ppm) of NO. Inhaled NO caused a dose-dependent fall in pulmonary vascular resistance (by 12% and 21%, with 5 and 40ppm, respectively; p<0.01, each) and improvement of PaO2 (by 25% and 23%; p<0.05, each), owing to the reduction of intrapulmonary shunt (by 23% and 27%; p<0.05, each), without changes in the amount of perfusion to low V;A/Q; ratio alveolar units. Patients with greater baseline intrapulmonary shunt exhibited greater improvement in arterial oxygenation (r2=0.55, p<0.05). We conclude that low doses of inhaled NO improve pulmonary gas exchange in acute severe pneumonia.

Equal ratio ventilation (1:1) improves arterial oxygenation during laparoscopic bariatric surgery: A crossover study

Background:Hypoxaemia and high peak airway pressure (Ppeak) are common anesthetic problems during laparoscopic bariatric surgery. Several publications have reported the successful improvement in arterial oxygenation using positive end expiratory pressure and alveolar recruitment maneuver, however, high peak airway pressure during laparoscopic bariatric surgery may limit the use of both techniques. This study was designed to determine whether equal I:E (inspiratory-to-expiratory) ratio ventilation (1:1) improves arterial oxygenation with parallel decrease in the Ppeak values.Methods:Thirty patients with a body mass index ≥40 kg/m2 scheduled for laparoscopic bariatric surgery were randomized, after creation of pneumoperitoneum, to receive I:E ratio either 1:1 (group 1, 15 patients) or 1:2 (group 2, 15 patients). After a stabilization period of 30 min, patients were crossed over to the other studied I:E ratio. Ppeak, mean airway pressure (Pmean), dynamic compliance (Cdyn), arterial blood gases and hemodynamic data were collected at the end of each stabilization period.Results:Ventilation with I: E ratio of 1:1 significantly increased partial pressure of O2 in the arterial blood (PaO2), Pmean and Cdyn with concomitant significant decrease in Ppeak compared to ventilation with I: E ratio of 1:2. There were no statistical differences between the two groups regarding the mean arterial pressure, heart rate, respiratory rate, end tidal CO2 or partial pressure of CO2 in the arterial blood.Conclusion:Equal ratio ventilation (1:1) is an effective technique in increase PaO2 during laparoscopic bariatric surgery. It increases Pmean and Cdyn while decreasing Ppeak without adverse respiratory or hemodynamic effects.

Pulsed delivery of inhaled nitric oxide counteracts hypoxaemia during 2.5 hours of inhalation anaesthesia in dorsally recumbent horses

ObjectiveThe study aimed to investigate the effect of varying pulse lengths of inhaled nitric oxide (iNO), and 2.5 hours of continuous pulse-delivered iNO on pulmonary gas exchange in anaesthetized horses. Study DesignExperimental study. AnimalsSix Standardbred horses. MethodsHorses received acepromazine, detomidine, guaifenesin, thiopentone and isoflurane in oxygen, were positioned in dorsal recumbency and were breathing spontaneously. iNO was on average pulsed during the first 20, 30, 43 or 73% of the inspiration in 15 minute steps. The pulse length that corresponded to the highest (peak) partial pressure of arterial oxygen (PaO2) in the individual horses was determined and delivered for a further 1.5 hours. Data measured or calculated included arterial and mixed venous partial pressures of O2 and CO2, heart rate, respiratory rate, expired minute ventilation, pulmonary and systemic arterial mean pressures, cardiac output and venous admixture. Data (mean ± SD) was analysed using anova with p < 0.05 considered significant. ResultsAlthough the pulse length of iNO that corresponded to peak PaO2 varied between horses, administration of all pulse lengths of iNO increased PaO2 compared to baseline. The shortest pulse lengths that resulted in the peak PaO2 were 30 and 43% of the inspiration. Administration of iNO increased PaO2 (12.6 ± 4.1 kPa [95 ± 31 mmHg] at baseline to a range of 23.0 ± 8.4 to 25.3 ± 9.0 kPa [173 to 190 mmHg]) and PaCO2 (8.5 ± 1.2 kPa [64 ± 9 mmHg] to 9.8 ± 1.5 kPa [73 ± 11 mmHg]) and decreased venous admixture from 32 ± 6% to 25 ± 6%. The increase in PaO2 and decrease in venous admixture was sustained for the entire 2.5 hours of iNO delivery. ConclusionsThe improvement in arterial oxygenation during pulsed delivery of iNO was significant and sustained throughout 2.5 hours of anaesthesia. Clinical relevancePulsed iNO potentially could be used clinically to counteract hypoxemia in anaesthetized horses.

Hypoxämie 4 Monate nach rechtsseitiger Pneumektomie

A 64-year-old male reported worsening dyspnea four months after right-sided pneumonectomy, due to lung cancer. Platypneu-or-thodeoxie syndrome was suspected due to a decrease in oxygen-saturation while the patient was in upright position. The shift of the right hemidiaphragm and liver caused compression of the right atrium and a shunt over a persistent foramen ovale. The right-to-left shunt was proven during right heart catheter. Interventional closure of the shunt resulted in immediate improvement of arterial oxygenation and a decrease in dyspnea.

Time-Dependent Alterations of VEGF and Its Signaling Molecules in Acute Lung Injury in a Rat Model of Sepsis

Molecular mechanisms of sepsis-associated acute lung injury (ALI) are poorly defined. Since vascular endothelial growth factor (VEGF) is a potent vascular permeability and mitogenic factor, it might contribute to the development of ALI in sepsis. Thus, using lipopolysaccharide (LPS)-induced (15mg/kg, intraperitoneal) endotoxemic rat model, we studied the timeline (1, 3, 6, and 10h) of pulmonary VEGF expression and its signaling machinery. Levels of pulmonary VEGF and its angiogenic-mediating receptor, Flk-1, were downregulated by LPS in a time-dependent manner; levels of plasma VEGF and its permeability-mediating receptor, Flt-1, in contrast, was upregulated with time. In addition, blockade of Flt-1 could improve the downregulated pulmonary VEGF level and attenuate the elevated plasma and pulmonary levels of TNF-α, followed by improvement of arterial oxygenation and wet-to-dry weight ratio of the lung. Expression of signaling, pro- and or apoptotic factors after LPS administration were as follows: phosphorylated Akt, a downstream molecule was downregulated time dependently; endothelial nitric oxide synthase levels were significantly reduced; pro-apoptotic markers caspase 3 and Bax were upregulated whereas levels of Bcl-2 were downregulated. The present findings show that VEGF may play a role through the expression of Flt-1 in LPS-induced ALI. Moreover, downregulation of VEGF signaling cascade may account for LPS-induced apoptosis and impaired physiological angiogenesis in lung tissues, which in turn may contribute to the development of ALI induced by LPS.

Physiologic responses and plasma endothelin-1 concentrations associated with abrupt cessation of nitric oxide inhalation in isoflurane-anesthetized horses

To assess physiologic responses and plasma endothelin (ET)-1 concentrations associated with abrupt cessation of nitric oxide (NO) inhalation in isoflurane-anesthetized horses. 6 healthy adult Standardbreds. Horses were anesthetized with isoflurane in oxygen and placed in dorsal recumbency. Nitric oxide was pulsed into the respiratory tract for 2.5 hours, and then administration was abruptly discontinued. Just prior to commencement and at cessation of NO administration, and at intervals during a 30-minute period following cessation of NO inhalation, several variables including PaO(2), mean pulmonary artery pressure, venous admixture or pulmonary shunt fraction (Qs/Qt), and plasma ET-1 concentration were recorded or calculated. After cessation of NO inhalation, PaO(2) decreased slowly but significantly (172.7 +/- 29.8 mm Hg to 84.6 +/- 10.9 mm Hg) and Qs/Qt increased slowly but significantly (25 +/- 2% to 40 +/- 3%) over a 30-minute period. Mean pulmonary artery pressure increased slightly (14.0 +/- 1.3 mm Hg to 16.8 +/- 1 mm Hg) over the same time period. No change in serum ET-1 concentration was detected, and other variables did not change or underwent minor changes. The improvement in arterial oxygenation during pulsed inhalation of NO to healthy isoflurane-anesthetized horses decreased only gradually during a 30-minute period following cessation of NO inhalation, and serum ET-1 concentration was not affected. Because a rapid rebound response did not develop, inhalation of NO might be clinically useful in the treatment of hypoxemia in healthy isoflurane-anesthetized horses.