Alveolar-arterial Oxygen Tension Difference Research Articles

The Association Between Alveolar-Arterial Oxygen Tension Difference and the Severity of COVID-19 in Patients.

Coronavirus disease 2019 (COVID-19) emerged as a global pandemic and resulted in a significantly high death toll. Therefore, there is an urgent need to find a potential biomarker related to the disease severity that can facilitate early-stage intervention. In the present study, we collected 242 laboratory-confirmed COVID-19-infected patients. The patients were grouped according to the alveolar to arterial oxygen tension difference (PA-aO2) value of COVID-19 infection after admission. Among the 242 laboratory-confirmed COVID-19- infected patients, 155 (64.05%) had an abnormal PA-aO2 value on admission. Compared with the normal PA-aO2 group, the median age of the abnormal PA-aO2 group was significantly older (p=0.032). Symptoms such as fever, cough, and shortness of breath were more obvious in the abnormal PA-aO2 group. The proportion of severe events in the abnormal PA-aO2 group was higher than the normal PA-aO2 group (10.34% vs. 23.23%, p=0.013). The abnormal PA-aO2 group had a higher possibility of developing severe events compared with the normal PA-aO2 group (HR 2.622, 95% CI 1.197-5.744, p=0.016). After adjusting for age and common comorbidities (hypertension and cardiovascular disease), the abnormal PA-aO2 group still exhibited significantly elevated risks of developing severe events than the normal PA-aO2 group (HR 2.986, 95% CI 1.220-7.309, p=0.017). Additionally, the abnormal PA-aO2 group had more serious inflammation/coagulopathy/fibrinolysis parameters than the normal PA-aO2 group. Abnormal PA-aO2 value was found to be common in COVID-19 patients, was strongly related to severe event development, and could be a potential biomarker for the prognosis of COVID-19 patients.

Correlation between alveolar-arterial oxygen tension difference gradient baseline with spirometry test in severe coronavirus disease 2019 (COVID-19)

Alveolar-arterial Oxygen Tension Differences are one of the oxygenations that can increase SARS-CoV-2 virus infection. Based on this, the researchers wanted to assess the relationship between the baseline AaDO2 gradient and spirometry tests in severe COVID-19 survivors. This research is an observational analytic study with a cross-sectional design. The analysis was carried out in bivariate and multivariate tests assisted by using SPSS 26. The subjects who participated in the study were 80 people. Subjects with AaDO2 values ​​> 39.4 mmHg 70% (n=56), median AaDO2 gradient was 60.45 (2.75 - 548.2 mmHg). The relationship between baseline AaDO2 analysis and spirometry results showed that it was associated with FVC and FEF25-75% results, respectively (PR) 18.6 (95% CI 3.978-87.401 p = <0.001) and (PR) 7.7 (95% CI 1.606-3.724 p = 0.011) and no significant with FEV1 and FEV1/FVC values. This study concludes a relationship between a high baseline AaDO2 gradient with FVC and FEF values ​​of 25-75% in severe adult COVID-19 survivors. There was no relationship between a high baseline AaDO2 gradient and FEV1 and FEV1/FVC values.

κ-Opioid Receptor Agonist U50448H Protects Against Acute Lung Injury in Rats with Cardiopulmonary Bypass via the CAP-NLRP3 Signaling Pathway.

Objective Acute lung injury (ALI) is one of the common and severe complications of cardiopulmonary bypass (CPB), which is the primary cause of death in intensive care units. Nevertheless, there is a lack of effective treatment for ALI secondary to CPB. κ-Opioid receptor (KOR) agonists have been demonstrated to improve lung function after pulmonary hypertension. However, its protective role has been barely reported in CPB-induced acute respiratory distress syndrome (ARDS). Therefore, this research focused on the protective effect of a KOR agonist U50448H on ARDS and investigated its potential relationship with the NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome. Method Forty-five rats were randomly allocated into Sham, CPB, and U50448 groups (n = 15 rats/group). After a CPB model was successfully established in rats, CPB rats were treated with the KOR agonist U50448H. The values of extravascular lung water (EVLW), alveolar-arterial oxygen tension difference (AaDO2), and respiratory index (RI) were examined, and the lung wet/dry (W/D) weight ratio was also calculated. Western blot (WB) was utilized to measure the expression of MMP-9, GSDMD-C, GSDMD-N, NLRP3, ASC, pro-Caspase-1, pro-IL-1β, and α7-nAChR. The immunofluorescence assay was performed for examining the expression of ROS, F480, iNOS, CD206, and α7-nAChR. Cell apoptosis was detected by the TUNEL assay. ELISA was used to test the level of LPS in serum and the level of MDA, GSH, SOD, TNF-α, IL-4, IL-6, IL-18, and IL-1β in lung tissues. Results It was observed that the administration of U50448H significantly reduced EVLW values and LPS levels in the lung of rats. Meanwhile, U50448H increased AaDO2 values while decreasing RI values. Moreover, the administration of U50448H alleviated the pathological damage caused by ALI secondary to CPB. U50448H repressed ROS release and oxidative stress responses, as well as lowered LPS levels in plasma and MMP-9 expression in the lung of CPB rats. Furthermore, U50448H facilitated the shift of macrophage phenotype to M2. In addition, U50448H decreased the activity of the CAP-NLRP3 inflammasome and suppressed pyroptosis in pulmonary cells. Conclusion The KOR agonist U50448H improved lung function and relieved lung injury in CPB rats, accompanied by diminished ROS and MMP-9 levels in lung tissues, promoted macrophage polarization from M1 to M2, and reduced NLRP3 inflammasome activities. These results indicated U50448H as a promising drug for the treatment of ALI secondary to CPB.

EFFECTS OF STRUCTURED MANUAL HYPERINFLATION FOR IMPROVING RESPIRATORY PARAMETRS IN POST-OPERATIVE CORONARY ARTERY BYPASS GRAFT PATIENTS

Purpose: Cardiopulmonary physiotherapy plays a crucial role in cardiac rehabilitation after surgeries. The deterioration of respiratory parameters occurs after coronary artery bypass grafting (CABG) procedure. Manual hyperinflation (MHI) is done according to clinical experiences and there are no specific guidelines for it. The objectives were to determine the effects of structured manual hyperinflation for improving respiratory parameters in post-operative CABG patients.
 Methodology: Duration of study was 6 months (January 2019-June 2019) with a sample size of 76 post-operative CABG patients. Non-probability purposive sampling technique was used. Patients were divided into two groups’ i-e MHI and VHI depending upon the treatment protocol. In protocol, endotracheal tube (ETT) suctioning was done followed by MHI and VHI in assigned group in randomized controlled trial design. Respiratory parameters were measured by ABG’S, equations for static lung compliance and alveolar-arterial oxygen tension difference. Data was recorded pre and post ETT suctioning, immediately, 30 min and 60 min post intervention. Both males and females were included. Inclusion criteria involves patient must be intubated, hemodynamically and vitally stable, and age range 55-77 years. Those were excluded who have past medical history of diagnosed pulmonary pathology and any post-operative complications. Patient was withdrawn from the study if any subject who have unstable cardiovascular status and high levels of respiratory support. Data was analyzed on SPSS 21.
 Findings: All the respiratory parameters showed significant differences (p<0.05) in pre and post values of structured MHI. Significant difference (p<0.05) was observed immediately after intervention in terms of acidity (pH), partial pressure of carbon oxide (PaCO2), partial pressure of oxygen (PaO2), oxygen saturation and arterial oxygen to fraction of inspired oxygen ratio between the groups with scores higher for experimental group. HCO3 showed significant difference (p<0.05) immediately after intervention and 30 min and 60 min post intervention with the scores higher for control group. Static lung compliance showed significant difference (p<0.05) at 30 min and 60 min post intervention with scores higher for control group. Alveolar-arterial oxygen tension showed no significant difference (p>0.05) between the groups at any point. No significant difference (p>0.05) was observed between the groups at any other point of measurement for all respiratory parameters. MHI and VHI are both effective in improving respiratory parameters in post-operative CABG patients but the values were more significant in MHI group. But the difference between the groups was not significant and conclusive.
 Recommendations: This study should be conducted in different patient populations having different pulmonary conditions and other types of cardiac surgeries and in other patients who are intubated and mechanically ventilated. Moreover, the effects of both techniques on different variables must be studied after multiple numbers of sessions during the whole period of intubation. 

Effect of Transcutaneous Electrical Acupoint Stimulation on One-Lung Ventilation-Induced Lung Injury in Patients Undergoing Esophageal Cancer Operation.

Objective To investigate the effect of transcutaneous electrical acupoint stimulation (TEAS) on one-lung ventilation-induced injury in patients undergoing esophageal cancer operation. Methods The participants (n = 121) were randomly assigned into TEAS and sham groups. The TEAS group was given transcutaneous electrical stimulation therapy. The acupoints selected were Feishu (BL13), Hegu (L14), and Zusanli (ST36) and were treated 30 minutes before induction of anesthesia; treatment lasts 30 minutes. The sham group was connected to the electrode on the same acupoints, but electronic stimulation was not applied. The levels of oxygenation index (PaO2/FiO2) and alveolar-arterial oxygen tension difference (A-aDO2) before one-lung ventilation (T1), 30 minutes after one-lung ventilation (T2), 2 hours after one-lung ventilation (T3), and 1 hour after the operation (T4) and the levels of serum tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-10 (IL-10) at T1, T2, T3, and 24 hours after the operation (T5) were taken as the primary endpoints. The incidence of postoperative pulmonary complications, removal time of thoracic drainage tube, and length of hospital stay were taken as the secondary endpoints. Results Compared with that, in the sham group, the level of PaO2/FiO2 in the TEAS group was significantly increased at T2, T3, and T4, and the level of A-aDO2 was significantly reduced at T2 and T3 (P < 0.05). Besides, compared with that, in the sham group, the level of serum TNF-α at T2, T3, and T5, as well as the level of serum IL-6 at T3 and T5, was significantly reduced, whereas the level of serum IL-10 at T3 was significantly increased (P < 0.05). The incidences of pulmonary infection and pleural effusion in the TEAS group were significantly lower than that in the sham group, and the removal time of thoracic drainage tube and the length of hospital stay in the TEAS group were significantly shorter than that in the sham group (P < 0.05). Conclusions TEAS could effectively increase the levels of PaO2/FiO2 and IL-10, reduce the levels of A-aDO2, TNF-α, and IL-6, and reduce the incidence of pulmonary complications. Moreover, it could also contribute to shorten the removal time of thoracic drainage tube and the length of hospital stay.

Effects of 12 and 17 cmH2O positive end-expiratory pressure applied after alveolar recruitment maneuver on pulmonary gas exchange and compliance in isoflurane-anesthetized horses

ObjectiveTo compare static compliance (Cst) and alveolar–arterial oxygen tension difference [P(a–a)O2] between positive end-expiratory pressures (PEEP) of 7, 12 and 17 cmH2O applied after an alveolar recruitment maneuver (RM) in isoflurane-anesthetized horses. Study designProspective, randomized, clinical study. AnimalsA group of 30 healthy adult horses undergoing arthroscopic surgery. MethodsAnimals in dorsal recumbency and mechanically ventilated with a tidal volume of 14 mL kg−1 and 7 cmH2O PEEP (control; n = 6) were subjected to an RM by increasing PEEP from 7 to 22 cmH2O in 5 cmH2O increments at 5 minute intervals, and then decreased similarly to PEEP of 17 (RM17; n = 8), 12 (RM12; n = 8) or 7 cmH2O (RM7; n = 8). Cst and P(a–a)O2 were assessed prior to (baseline) and after the RM at 5, 10, 15, 20, 40, 60 and 80 minutes after achieving each target PEEP, and during recovery from anesthesia. ResultsPost-RM improvements on P(a–a)O2 were maintained (baseline versus 80 minutes) in RM12 [216 ± 77 mmHg (28.8 ± 10.3 kPa) versus 194 ± 39 mmHg (25.9 ± 5.2 kPa)] and RM17 [180 ± 86 mmHg (24.0 ± 11.6 kPa) versus 136 ± 75 mmHg [18.2 ± 10.0 kPa]). The improvements on Cst were maintained only in RM12 (0.80 ± 0.13 versus 0.98 ± 0.13 mL cmH2O−1 kg−1). No such improvements were observed in RM7 and control. No significant differences were observed between groups during recovery from anesthesia. Conclusionsand clinical relevance The 12 and 17 cmH2O PEEP can be used to maintain the improvements on P(a–a)O2 obtained after an RM. Only 12 cmH2O PEEP maintained the post-RM increase on Cst. Such variables were not influenced by the 7 cmH2O PEEP.

Efficacy of PCV-VG mode for lung protective ventilation in patients requiring one-lung ventilation during thoracoscopic surgery

Objective To evaluate the efficacy of pressure-controlled volume-guaranteed (PCV-VG) mode for lung protective ventilation in patients requiring one-lung ventilation (OLV) during thoracoscopic surgery. Methods Sixty patients, aged 50-70 yr, with body mass index of 18-26 kg/m2, of American Society of Anesthesiologists physical status Ⅰ or Ⅱ, scheduled for elective radical resection of esophageal cancer performed via video-assisted thoracoscope under general anesthesia, were divided into 2 groups (n=30 each) using a random number table: volume-controlled ventilation group (group V) and PCV-VG group (group P). The ventilator settings were adjusted, with a tidal volume 10 ml/kg and respiratory rate 10-12 breaths/min during two-lung ventilation, and with a tidal volume 6 ml/kg and respiratory rate 12-16 breaths/min during OLV.The inspiratory/expiratory ratio was 1∶2, pressure restriction was 35 cmH2O, and 33% oxygen was inhaled at 2 L/min.The end-tidal pressure of carbon dioxide was maintained at 35-40 mmHg.Visual analog scale score was maintained ≤ 3 after operation.After admission to the operation room (T0) and at 1, 3 and 7 days after operation (T1-3), forced vital capacity (FVC), forced expiratory volume in first second (FEV1), and maximal mid-expiratory flow (MMEF) were measured, arterial blood samples were collected for blood gas analysis, arterial carbon dioxide partial pressure and arterial oxygen partial pressure (PaO2) were recorded, and alveolar-arterial oxygen tension difference (PA-aO2)was calculated.Clinical Pulmonary Infection Score was assessed at T1, T2 and T3.The chest tube removal time and length of postoperative hospital stay were recorded. Results Compared with the baseline at T0, FVC, FEV1, MMEF and PaO2 were significantly decreased, and PA-aO2 was increased at T1-3 in the two groups (P<0.05). Compared with group V, FVC, FEV1, MMEF and PaO2 were significantly increased, PA-aO2 and Clinical Pulmonary Infection Score were decreased, and the chest tube removal time and length of postoperative hospital stay were shortened at T1-3 in group P (P<0.05). Conclusion PCV-VG mode can achieve lung protective ventilation, which is helpful in improving outcomes in the patients requiring OLV during thoracoscopic surgery. Key words: Respiration, artificial; Thoracoscopy

The Effect of Transcutaneous Electrical Acupoint Stimulation on Inflammatory Response in Patients Undergoing Limb Ischemia-Reperfusion.

Reperfusion after tourniquet use can induce inflammation and cause remote organ injury. We evaluated the therapeutic effect of transcutaneous electrical acupoint stimulation (TEAS) on inflammatory mediators and lung function in patients receiving lower limb tourniquets. Forty patients undergoing unilateral lower extremity surgery with tourniquet were randomly assigned to two groups: the TEAS group and ischemia-reperfusion (I/R) group. The C-C motif chemokine ligand 2 (CCL2), C-X-C motif chemokine ligand 8 (CXCL8), interleukin-1 (IL-1), interleukin-6 (IL-6), interleukin-10 (IL-10), tumor necrosis factor-α (TNF-α), and arterial blood gas analysis were measured preoperatively and 6 h after tourniquet removal. The levels of CXCL8, IL-1, IL-6, TNF-α, and CCL2 were significantly increased compared to baseline values in both groups, but the increase was significantly smaller in the TEAS group. In the TEAS group, the partial pressure of oxygen and arterial-alveolar oxygen tension ratio were significantly decreased, and the alveolar-arterial oxygen tension difference and respiratory index were significantly increased, compared to those in the I/R group at 6 h after reperfusion. In conclusion, TEAS diminished the upregulation of proinflammatory factors in response to lower limb ischemia-reperfusion and improved pulmonary gas exchange.

Neutrophil Elastase Inhibitor Following Liver Resection: A Matched Cohort Study.

Background:Sivelestat is a neutrophil elastase inhibitor (NEI) with positive impact on the respiratory complications in thoracic surgery. Based on the findings of a recent study, NEI may have a good response for avoiding ischemia reperfusion injury in liver resection.Objectives:The current study aimed to examine the impact of NEI on the postoperative outcomes after liver resection.Patients and Methods:The data were collected from 374 consecutive patients scheduled to undergo liver resection. Seven perioperative variables were matched on the basis of the patients’ background. Then, the NEI (n = 61) and control (n = 61) groups were compared. NEI was administered at a dose of 0.2 mg/kg/h for three days from the postoperative day 0 (POD0). The liver function, coagulation activity, inflammatory response, respiratory complications, and overall complications were compared.Results:The levels of serum interleukin-6 (NEI group: 113 pg/mL [26.9 - 522.0] vs. control group: 174 [28.6 - 1040.6], P < 0.01) and C-reactive protein (CRP) (2.9 IU/L [range: 0.1 - 8.6] vs. 4.11 [0.3 - 13.8], P = 0.01) on the first postoperative day (POD1) and the alveolar-arterial oxygen tension difference (32.3 Torr [-28.6 - 132.3] vs. 46.6 [-11.2 - 251.6], P = 0.04) on the third postoperative day (POD3) were significantly lower in the NEI group than the control group. The rate of pleural effusion was significantly lower in the NEI group compared to that of the control group [13 patients (21.3%) vs. 23 (37.7%), P = 0.04]. However, the coagulation activities (P = 0.68), liver function (P = 0.69), non-respiratory complications (P = 0.84), and overall complications (P = 0.71) did not differ significantly between the groups.Conclusions:Intravenous NEI administration had positive impact on the postoperative inflammatory response and oxygenation while it did not affect either coagulation or the liver function, as well as severe grade complications following resection.

Assessment of acute lung injury/acute respiratory distress syndrome using B-type brain natriuretic peptide.

To investigate the clinical value of B-type natriuretic peptide (BNP) in the assessment of severity and prognosis in acute lung injury/acute respiratory distress syndrome (ALI/ARDS). Plasma BNP level, arterial blood gases, serum C-reactive protein level, alveolar-arterial oxygen tension difference and oxygenation index were measured in patients with and without ALI/ARDS within 24 h of admission to an intensive care unit. Patients with ALI/ARDS were divided into mild, moderate or severe groups according to the degree of hypoxaemia. Survival >28 days was recorded. A total of 59 patients with ALI/ARDS and 14 patients without ALI/ARDS were included in the study. Of the patients with ALI/ARDS, 18 had mild hypoxaemia, 20 had moderate hypoxaemia and 21 had severe hypoxaemia. The mean ± SD BNP level was significantly higher in all three ALI/ARDS groups (92.41 ± 28.19 pg/ml, 170.64 ± 57.34 pg/ml and 239.06 ± 59.62 pg/ml, respectively, in the mild, moderate and severe groups) than in the non-ALI/ARDS group (47.27 ± 19.63 pg/ml); the increase in BNP level with increasing severity was also statistically significant. When divided according to outcome, the BNP level in the death group (267.07 ± 45.06 pg/ml) was significantly higher than in the survival group (128.99 ± 45.42 pg/ml). The BNP level may be of value in evaluating severity and prognosis in patients with ALI/ARDS.

The effect of the inspired oxygen fraction on arterial blood oxygenation in spontaneously breathing, isoflurane anaesthetized horses: a retrospective study

ObjectivesTo investigate the influence of two inspired oxygen fractions (FIO2) on the arterial oxygenation in horses anaesthetized with isoflurane. Study DesignRetrospective, case-control clinical study. AnimalsTwo hundred equine patients undergoing non-abdominal surgery (ASA class 1–2), using a standardized anaesthetic protocol and selected from anaesthetic records of a period of three years, based on pre-defined inclusion criteria. MethodsIn group O (n = 100), medical oxygen acted as carrier gas, while in group M (n = 100), a medical mixture of oxygen and air (FIO2 0.60) was used. Demographic data, FIO2, arterial oxygen tension (PaO2) and routinely monitored physiologic data were recorded. The alveolar-arterial oxygen tension difference [P(A-a)O2] and PaO2/FIO2 ratio were calculated. The area under the curve, standardized to the anaesthetic duration, was calculated and statistically compared between groups using t-tests or Mann–Whitney tests as appropriate. Categorical data were compared using Chi-square tests. ResultsNo significant differences in age, body weight, sex, breed, surgical procedure, position, anaesthetic duration or arterial carbon dioxide tension were found. Mean FIO2 was 0.78 in group O and 0.60 in group M. Compared to group O, significantly lower values for PaO2 and for P(A-a)O2 were found in group M. In contrast, the PaO2/FIO2 ratio and the percentage of horses with a PaO2 <100 mmHg (13.33 kPa) were comparable in both groups. ConclusionsAlthough a reduction of the inspired oxygen fraction resulted in a lower PaO2, the P(A-a)O2 was also lower and the number of horses with PaO2 values <100 mmHg was comparable. Clinical relevanceIn healthy isoflurane anaesthetized horses, the use of a mixture of oxygen and air as carrier gas seems acceptable, but further, prospective studies are needed to confirm whether it results in a lower degree of ventilation/perfusion mismatching.

The effects of anesthesia, muscle paralysis, and ventilation on the lung evaluated by lung diffusion for carbon monoxide and pulmonary surfactant protein B.

An increased alveolar-arterial oxygen tension difference is frequent in anesthetized patients. In this study, we evaluated the effect on the lung of anesthesia, muscle paralysis, and a brief course of mechanical ventilation. Lung diffusion for carbon monoxide (DLCO), including pulmonary capillary blood volume (Vc) and conductance of the alveolar-capillary membrane (DM), and pulmonary surfactant protein type B (a marker of alveolar damage) were measured in 45 patients without pulmonary disease undergoing extrathoracic surgery. Anesthesia, muscle paralysis, and mechanical ventilation led to impairment of gas exchange, with a reduction of DLCO values immediately after anesthetic induction due to a concomitant reduction of both DM and Vc. While changes in DM were due to the reduction of lung volume, changes in Vc were not limited to volume loss, since the Vc/alveolar volume ratio decreased significantly. Although DLCO and its components decreased immediately after induction, none of the values decreased further at 1 and 3 hours. Surfactant protein type B, however, was unchanged immediately after anesthesia but increased at 1 hour after induction and further increased after 3 hours of anesthesia. The level of alveolar damage correlated with the reduction of lung perfusion and lung dynamic strain (i.e., ratio between tidal volume and end-expiratory lung volume). A brief course of anesthesia and controlled ventilation leads to: (1) alveolar damage, which is correlated with lung strain and perfusion, and (2) impaired gas exchange mainly due to volume loss but also to reduced aerated lung perfusion.

Effect of nasal continuous positive airway pressure and Bi-phase positive airway pressure on oxygen exchange indexes in newborns with mild to moderate neonatal respiratory distress syndrome

Objective To observe the effect of nasal continuous positive airway pressure (nCPAP) and Bi-phase positive airway pressure (BIPAP) on the oxygen exchange indexes in newborns with mild to moderate neonatal respiratory distress syndrome (NRDS). Methods After infusion of pulmonary surfactant into lung bilaterally, 116 cases with mild to moderate NRDS were treated with nCPAP(nCPAP group, n=75) and BIPAP(BIPAP group, n=41) respectively.Oxygen exchange indexes including arterial partial pressure of oxygen[pa(O2)], modified oxygenation index(P/F), alveolar- arterial oxygen tension difference(A-aDO2), respiratory index(RI), artery /alveolar oxygen partial pressure ratio[pa(O2)/pA(O2)] and pulmonary shunt fraction(Qs/Qt) were measured or calculated at 0 (before treatment), 2, 8 and 24 h after being treated with nCPAP or BIPAP. Results Six different oxygen exchange indexes of pa(O2), P/F, A-aDO2, RI, pa(O2)/pA(O2) and Qs/Qt in both groups didn't show statistical significance at 0 hour: pa(O2)(kPa)(6.1±0.6 vs 6.1±0.6, t=0.11, P>0.05), P/F(kPa)(15.59±1.45 vs 15.71±1.45, t=1.59, P>0.05), A-aDO2(kPa)(6.04±0.64 vs 6.24±0.69, t=1.59, P>0.05), RI(6.0±1.0 vs 6.2±1.1, t=1.35, P>0.05), pa(O2)/pA(O2) (0.24±0.02 vs 0.25±0.03, t=1.63, P>0.05)and Qs/Qt(%)(11.9±1.6 vs 11.6±1.6, t=1.10, P>0.05). A-aDO2, RI, pa(O2)/pA(O2) and Qs/Qt of BIPAP group had more improvement than those of nCPAP at 2 and 24 h, and oxygen exchange indexes at 2 h of BIPAP group and those of nCPAP group were: A-aDO2(kPa)(3.83±0.49 vs 4.24±0.67, t=18.26, P 0.05), P/F(28.49±3.17 vs 31.85±2.85, t=3.76.P>0.05)]. Nineteen cases in nCPAP group needed invasive mechanical ventilation, and only 3 cases in BIPAP group underwent the procedure; there was a significant difference (χ2=4.01, P<0.05). Oxygen exchange indexes in both groups were gradually improved from 2 h, 8 h to 24 h, but 22 deteriorated cases showed no improvement, who underwent invasive ventilation.Positive end-expiratory pressure(PEEP) positive airway pressure (EPAP) was (0.42±0.19) kPa in BIPAP group, and (0.56±0.23) kPa in nCPAP group(t=3.45, P<0.01). Conclusions 1.BIPAP and nCPAP can improve the ability of oxygen exchange in newborns with mild to moderate NRDS, but BIPAP is more effective than nCPAP, which can shorten the possibility of invasive ventilation and reduce the PEEP level.2.pa(O2), P/F, pa(O2)/pA(O2) and RI may be more suitable for evaluating oxygen exchange for neonatal NRDS. Key words: Neonatal respiratory distress syndrome; Noninvasive ventilation; Arterial partial pressure of oxygen; Oxygenation index; Alveolar arterial oxygen tension difference; Respiratory index; Arterial/alveolar oxygen partial pressure ratio; Pulmonary shunt fraction

Heliox augmented mechanical ventilation in the treatment of premature infants with respiratory distress syndrome

The aim of the study was to assess the influence of mechanical ventilation with helium-oxygen mixture (heliox) on basic vital signs, oxygenation, acid-base balance and respiratory mechanics in newborns with respiratory distress syndrome (RDS), previously treated with surfactant. The study was carried out in preterm newborns with respiratory failure requiring mechanical ventilation due to RDS, requiring Fi02>0.4 after a single dose of surfactant. Patients were ventilated using PC-SIMV Parameters of mechanical ventilation, respiratory function, oxygenation, acid-base balance and vital signs were recorded at baseline, one hour during and one hour after heliox ventilation. Ten newborns with RDS were enrolled in the study Mechanical ventilation with heliox did not affect vital signs and patient general condition remained stable during and after ventilation with heliox. Mechanical ventilation with heliox was associated with a statistically significant increase in tidal volume (mean 5.48 vs. 6.55 ml/kg). There were no significant changes in minute ventilation and peak expiratory flow rate. Mechanical ventilation with heliox allowed the use of significantly lower fractions of inspired oxygen (mean 0.55 vs. 0.35), with a significant decrease in the oxygenation index (mean 8.77 vs. 5.02) and alveolar-arterial oxygen tension difference (mean 263.81 vs. 113.28 mm Hg). After ventilation with this gas mixture was stopped, the patients required higher Fi02, 01 and AaD02 levels increased. Mechanical ventilation with heliox was safe, improved oxygenation and caused an increase in tidai, volume in newborns with RDS previously treated with surfactant.

Heliox for mechanically ventilated newborns with bronchopulmonary dysplasia

ObjectiveWe assessed the safety and studied the influence of short-term helium–oxygen (heliox) mechanical ventilation (MV) on respiratory function, gas exchange and oxygenation in infants with bronchopulmonary dysplasia (BPD) or at...

Role of serine threonine protein kinase-1 and Smad3 in lung tissues in development of hepatopulmonary syndrome in rats

Objective To investigate the role of serine threonine protein kinase-1 (Akt1) and Smad3 in lung tissues in development of hepatopulmonary syndrome in rats.Methods Seventy-two healthy male SpragueDawley rats,aged 3-4 months,weighing 200-250 g,were randomly divided into 3 groups (n=24 each):control group (C group),sham operation group (S group) and common bile duct ligation (CBDL) group.The rats were anesthetized with 3％ pentobarbital sodium 45 mg/kg.In group CBDL,laparotomy was performed,the common bile duct was ligated and then the abdomen was closed,while the common bile duct was only exposed,but not ligated and then the abdomen was closed in group S.At 1st,3rd and 5th weeks (T1-3),8 rats were chosen randomly in each group and blood samples were obtained from the abdominal aorta for blood gas analysis.The rats were then sacrificed and lungs were isolated to detect the expression of Aktl and Smad3 mRNA and protein in lung tissues (by RT-PCR and Western blot).The lung tissues were sliced and stained with hematoxylin eosin for examination of the pathological changes of pulmonary capillaries.Results Compared with C and S groups,the expression of Akt1 and Smad3 mRNA and protein in lung tissues was significantly up-regulated at T2,3,and alveolar-arterial oxygen tension difference was increased at T3 in CBDL group (P ＜ 0.05).The pulmonary capillary was obviously dilated at T3 in CBDL group.Conclusion The expression of Akt1 and Smad3 in lung tissues is up-regulated,which may be one of the mechanisms of development of hepatopulmonary syndrome in rats. Key words: Hepatopulmonary syndrome ; Lung ; Protein-serine-threonine kinases ; Smad3 protein

Optimal positive end-expiratory pressure during robot-assisted laparoscopic radical prostatectomy.

BackgroundIncreased intra-abdominal pressure during laparoscopic surgery causes cephalad displacement of the diaphragm, resulting in the formation of atelectasis, which can be overcome by positive end-expiratory pressure (PEEP). The aim of this prospective study was to investigate the level of optimal PEEP to maintain adequate arterial oxygenation and hemodynamics during robot-assisted laparoscopic radical prostatectomy (RLRP).MethodsOne hundred patients undergoing RLRP were randomly allocated to one of five groups (n = 20) (0, 3, 5, 7 and 10 cmH2O of PEEP). Hemodynamic variables and respiratory parameters were measured at baseline with the patient in the supine position; at 30 min, 1, 2, 3 and 4 h during CO2 insufflation with the patient in the post-Trendelenburg position; and after deflation in the supine position with increasing PEEP.ResultsThe PaO2 levels and alveolar-arterial difference in oxygen tension (AaDO2) were improved in patients with PEEPs compared with patients in whom PEEP was not used. The application of PEEP (10 cmH2O) resulted in higher PaO2 levels compared to those with lower PEEP levels, but excessive peak airway pressure (PAP) was sometimes observed. The application of a PEEP of 7 cmH2O resulted in similar PaO2 levels without causing excessive PAP. There was a significant difference in central venous pressure between the groups, but there were no significant differences in heart rate, mean arterial pressure or minute ventilation between the groups.ConclusionsA PEEP of 7 cmH2O is associated with the greater improvement of PaO2 and AaDO2 without causing excessive PAP during RLRP.

Comparison of Respiratory Mechanics in Adult Patients Undergoing Minimally Invasive Repair of the Pectus Excavatum and Removal of a Pectus Bar

The objective of this study was to compare the respiratory mechanics and gas exchange in adult patients undergoing minimally invasive repair of the pectus excavatum (MIRPE group) and removal of a pectus bar (bar removal group). A prospective observational study. A tertiary university hospital. Thirty-two patients scheduled for elective MIRPE or removal of a pectus bar. None. Spirometry was used to measure the peak inspiratory airway pressure (PIP), static compliance, and respiratory resistance. The measurements were recorded at 1 minute after beginning mechanical ventilation (T0), 15 minutes after beginning sevoflurane inhalation (T1), and after the insertion (or removal) of a pectus bar through the chest wall (T2). Pulmonary gas exchange was assessed by calculating the alveolar arterial oxygen tension difference (AaDO2) before surgical incision and after insertion (or removal) of the pectus bar. In the MIRPE group, static compliance was decreased significantly (p < 0.001), and PIP was increased significantly (p < 0.001) after insertion of the pectus bar (T2) compared with baseline. In contrast, the bar removal group showed the opposite results. There were significant differences in static compliance and PIP at T2 between the groups (p = 0.002 and 0.026, respectively). AaDO2 was increased significantly in the MIRPE group compared with the bar removal group (p = 0.012). Insertion of the pectus bar through the chest wall results in significant changes in respiratory mechanics and gas exchange. Therefore, close attention to pulmonary function is required during and after these surgical procedures.

Effect of NaCl/Hydroxyethyl Starch 200/0.5 on Lung Function and Hemodynamics in Patients Operated on under Extracorporeal Circulation

Objective: to study the effect of 7.2% NaCl/hydroxyethyl starch 200/0.5 on extravascular lung water and respiratory and cardiovascular systems in patients with coronary heart disease (CHD) after myocardial revascularization under extracorporeal circulation (EC). Subjects and methods. A prospective, randomized study was conducted in 40 patients with coronary artery disease. A study group (n=20) received 7.2% NaCl/hydroxyethyl starch 200/0.5; a control group (n=20) had 0.9% NaCl in a dose of 4 ml/kg within 30 min before EC. Extravascular lung water and central hemodynamic parameters were assessed using transpulmonary thermodilution and a Swan-Ganz catheter; respiratory function was estimated by the arterial oxygenation index, alveolar-arterial oxygen tension difference, and venous shunt fraction. Plasma osmolality and Na concentration were determined using an Osmomat 030 device. Conclusion. The intraoperative use of 7.2% NaCl/hydroxyethyl starch 200/0.5 in patients with CHD leads to a significant reduction in extravascular lung water after myocardial revascularization, thereby effectively protecting pulmonary oxygenizing function. The single administration of 7.2% NaCl/hydroxyethyl starch causes a short-term increase in cardiac index and it is a relatively safe in preventing neurological disorders and heart failure. Key words: 7.2% NaCl/hydroxyethyl starch 200/0.5; extravascular lung water, respiratory function, cardiac index, osmolarity.

Hypertonic Solution Decreases Extravascular Lung Water in Cardiac Patients Undergoing Cardiopulmonary Bypass Surgery

To test the hypothesis that the infusion of hypertonic solution would decrease extravascular lung water postoperatively and thus improve pulmonary function. Prospective, randomized, blinded trial. Tertiary cardiothoracic referral center. Twenty-six patients with coronary artery disease who underwent surgery with cardiopulmonary bypass (CPB). Patients were allocated randomly to receive 4 mL/kg of 7.2% NaCl/hydroxyethyl starch, 200/0.5 (HSH group) or an equal volume of 0.9% NaCl (control group) for 30 minutes starting after anesthesia induction. The extravascular lung water index, hemodynamic and biochemical data, and the rate of complications were analyzed. The extravascular lung water index was significantly lower (7 v 9.5 mL/kg) in the HSH group at the first postoperative day (p < 0.01). The index of arterial oxygenation efficiency was significantly higher at 5 minutes and 2 and 4 hours after cardiopulmonary bypass (CPB) in the HSH group (p < 0.05). The alveolar-arterial oxygen tension difference was significantly lower at 5 minutes and 2 and 4 hours after CPB in the HSH group (p < 0.01). The cardiac index was significantly higher at 5 minutes after infusion in the HSH group (p < 0.05). The infusion of HSH leads to significant decreases in the extravascular lung water index during and after cardiac surgery and is associated with better preservation of pulmonary function and transient increases in the cardiac index. Further trials are needed to clarify the clinical advantages of hypertonic solution administration in patients undergoing surgery with CPB.