Difference In PaO2 Research Articles

A Novel Method to Improve the Identification of Time of Intubation for Retrospective EHR Data Analysis During a Time of Resource Strain, the COVID-19 Pandemic.

Accurate determinations of the time of intubation (TOI) are critical for retrospective electronic health record (EHR) data analyses. In a retrospective study, the authors developed and validated an improved query (Ti) to identify TOI across numerous settings in a large health system, using EHR data, during the COVID-19 pandemic. Further, they evaluated the affect of Ti on peri-intubation patient parameters compared to a previous method—ventilator parameters (Tv). Ti identified an earlier TOI for 84.8% (n = 1666) of cases with a mean (SD) of 3.5 hours (15.5), resulting in alternate values for: partial pressure of arterial oxygen (PaO2) in 18.4% of patients (mean 43.95 mmHg [54.24]); PaO2/fractional inspired oxygen (FiO2) in 17.8% of patients (mean 48.29 [69.81]), and oxygen saturation/FiO2 in 62.7% (mean 16.75 [34.14]), using the absolute difference in mean values within the first 4 hours of intubation. Differences in PaO2/FiO2 using Ti versus Tv resulted in the reclassification of 7.3% of patients into different acute respiratory distress syndrome (ARDS) severity categories.

Application value of non-invasive ventilation combined with high flow nasal cannula oxygen therapy in sequential treatment of patients with chronic obstructive pulmonary disease after mechanical ventilation

Objective: To investigate the value of non-invasive ventilation (NIV) combined with high flow nasal cannula oxygen therapy (HFNCO) in sequential treatment of patients with chronic obstructive pulmonary disease after mechanical ventilation. Methods: Chronic obstructive pulmonary disease with acute exacerbation (AECOPD) patients with invasive mechanical ventilation (MV) and successful withdrawal admitted into Huxi Affiliated Hospital of Jining Medical College from January 2018 to December 2019 were enrolled for perspective study. The patients were divided into treatment group (n=40) and control group (n=33) by random number table method. The treatment group was given NIV and HFNCO, the control group was given NIV treatment alone. Bedside ultrasound was used to measure the patients' diaphragmatic motion, and the differences between the two groups of patients before treatment, 24, 48 and 72 h after treatment were compared in diaphragmatic excursions during quiet breathing (DEq), diaphragmatic excursions during deep breathing(DEd), diaphragmatic shallow fast breathing index (D-RSBI), arterial oxygen partial pressure (PaO(2)), arterial partial pressure of carbon dioxide (PaCO(2)), re-tracheal intubation rate, mortality rate for 28 days and average duration of NPPV treatment within 3 days. Results: There were no statistically significant differences in DEq, DEd, D-RSBI, PaO(2) and PaCO(2) between the two groups before treatment (all P>0.05). After 24 h treatment, DEd decreased in both groups, D-RSBI increased in both groups, However, D-RSBI [(1.33±0.56) vs (1.62±0.59) times·min(-1)·mm(-1)] in the treatment group was significantly lower than the control group, P=0.034. After 72 h treatment, DEd [(41.4±8.1) vs (37.8±6.0) mm] was significantly higher than the control group, D-RSBI [(1.02±0.27) vs (1.22±0.43) times·min(-1)·mm(-1)] was significantly lower than the control group (all P<0.05). The average duration of NIV treatment time [(7.5±1.2) vs (9.3±2.6) h] in the treatment group was significantly shorter than that in the control group (P<0.01). There were no statistically significant differences in PaO(2), PCO(2), re-tracheal intubation rate and the mortality rate of 28 days. Conclusion: NIV combined with HFNCO sequential therapy can effectively relieve diaphragm fatigue and promote recovery of respiratory muscle strength, and it's better than NIV alone.

Effect of different mechanical ventilation modes on patient-ventilator synchrony and diaphragm function in rabbit model of acute respiratory distress syndrome

Objective: To observe the effect of different modes of mechanical ventilation on patient-ventilator synchrony and diaphragm function in rabbits with acute respiratory distress syndrome(ARDS). Methods: Eighteen New Zealand rabbit models of ARDS were induced by intratracheal infusion hydrochloric acid until the oxygenation index (PaO(2)/FiO(2)) was less than 200 mmHg, and then divided into three groups with random number: assisted-controlled mechanical ventilation (A/C) group, pressure support ventilation (PSV) group and neurally adjusted ventilatory assist (NAVA) group. All of them were ventilated for four hours with the targeted tidal volume (V(T)) (6 ml/kg) and the positive end-expiratory pressure (PEEP) titrated with the maximum oxygenation method. Gas exchange, pulmonary mechanics and patient-ventilator synchrony were determined during 4 h of ventilation and the concentrations of malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione (GSH) in diaphragm were measured after 4 h of ventilation. The q test was used for the multiple comparison of the sample mean. Results: There were no significant differences in PaO(2)/FiO(2) between three groups during ventilation 1-4 h (F=1.029, P>0.05). The V(T) in NAVA group was obviously lower than that in PSV group and the respiratory rate (RR) and the electrical activity of diaphragm(EAdi) were higher than those in A/C group(all P<0.05).The trigger delay and off cycle delay the in NAVA group were markedly lower than those in A/C and PSV group during ventilation 1-4 h(F=14.312, 9.342, both P<0.05). Asynchrony index in NAVA group (3.1%±1.0%) was obviously lower than those in A/C group (22.3%±5.2%) and PSV group(8.4%±2.3%) (F=7.192, P<0.05). In NAVA group, peak EAdi (EAdi(peak)) and peak airway pressure (Ppeak) were markedly correlated (r=0.97±0.16, P<0.05), while Ppeak delivery in A/C and PSV group was not correlated to EAdi(peak) (r=0.38±0.13,0.46±0.15, both P>0.05).Compared with A/C group, the concentration of MDA in the diaphragm in NAVA group was obviously lower(P<0.05). SOD and GSH level inthe diaphragm in NAVA group were both obviously higher than those in A/C group (both P<0.05). Conclusions: It is helpful to avoid eccentric contraction of diaphragm, lessen oxidative stress and alleviate ventilator-related diaphragm dysfunction by keeping spontaneous breathing as far as possible and subject-ventilator synchrony when ventilation in ARDS with NAVA.

Effects of hydrogen on the lung damage of mice at early stage of severe burn

Objective: To investigate the effects of hydrogen on the lung damage of mice at early stage of severe burn. Methods: One hundred and sixty ICR mice were divided into sham injury, hydrogen, pure burn, and burn+ hydrogen groups according to the random number table, with 40 mice in each group. Mice in pure burn group and burn+ hydrogen group were inflicted with 40% total body surface area full-thickness scald (hereafter referred to as burn) on the back, while mice in sham injury group and hydrogen group were sham injured. Mice in hydrogen group and burn+ hydrogen group inhaled 2% hydrogen for 1 h at post injury hour (PIH) 1 and 6, respectively, while mice in sham injury group and pure burn group inhaled air for 1 h. At PIH 24, lung tissue of six mice in each group was harvested, and then pathological changes of lung tissue were observed by HE staining and the lung tissue injury pathological score was calculated. Inferior vena cava blood and lung tissue of other eight mice in each group were obtained, and then content of high mobility group box 1 (HMGB1) and interleukin-6 (IL-6) in serum and lung tissue was determined by enzyme-linked immunosorbent assay. Activity of superoxide dismutase (SOD) in serum and lung tissue was detected by spectrophotometry. After arterial blood of other six mice in each group was collected for detection of arterial partial pressure of oxygen (PaO(2)), the wet and dry weight of lung tissue were weighted to calculate lung wet to dry weight ratio. The survival rates of the other twenty mice in each group during post injury days 7 were calculated. Data were processed with one-way analysis of variance, LSD test and log-rank test. Results: (1) At PIH 24, lung tissue of mice in sham injury group and hydrogen group showed no abnormality. Mice in pure burn group were with pulmonary interstitial edema, serious rupture of alveolar capillary wall, and infiltration of a large number of inflammatory cells. Mice in burn+ hydrogen group were with mild pulmonary interstitial edema, alveolar capillary congestion accompanied by slight rupture and bleeding, and the number of infiltration of inflammatory cells was smaller than that in pure burn group. The lung tissue injury pathological scores of mice in sham injury group, hydrogen group, pure burn group, and burn+ hydrogen group were (0.7±0.5), (0.8±0.5), (6.1±1.0), and (2.8±0.8) points, respectively. The lung tissue injury pathological score of mice in pure burn group was significantly higher than that in sham injury group (P 0.05). (5) At PIH 24, the ratios of lung wet to dry weight of mice in sham injury, hydrogen, pure burn, and burn+ hydrogen groups were 3.52±0.22, 3.61±0.24, 7.24±0.32, and 5.21±0.41, respectively. The ratio of lung wet to dry weight of mice in pure burn group was significantly higher than that in sham injury group (P<0.001). The ratio of lung wet to dry weight of mice in burn+ hydrogen group was significantly lower than that in pure burn group (P<0.001). (6) The survival rates of mice in sham injury group and hydrogen group during post injury days 7 were 100%. Compared with those in sham injury group, survival rates of mice in pure burn group from post injury days 3 to 7 were significantly decreased (with P values below 0.05). Compared with those in pure burn group, survival rates of mice in burn+ hydrogen group from post injury days 5 to 7 were significantly increased (with P values below 0.05). Conclusions: Hydrogen can significantly alleviate the infiltration of inflammatory cells and improve the pathological lesions of lung tissue of mice with severe burn. It has the effects of reducing inflammatory reaction and inhibiting oxidative stress, further showing the protective effect on the lung of burn mice.

The changes and significance of multiple organ functions in acute pancreatitis patients under hypoxic condition on plateau

To explore characteristics of the pathogenesis and progression of the acute pancreatitis (AP) in high altitude and the relationship between AP and plateau erythrocythemia. Retrospective analysis of the clinical data of AP was conducted for 103 inpatients who were admitted during 2003 and 2005 to the People's Hospital of Qinghai Province, including 12 cases of AP complicated with plateau erythrocythemia and 91 cases of AP no complicating plateau erythrocythemia. The patients were divided into a group of 57 cases living in high altitude (>3 000 m) and 46 patients in lower altitude group (<2 200 m). Clinical data of the patients were collected at admission, and liver, kidney and lung functions were determined for all patients. Alanine aminotransferase (ALT) and creatinine (Cr) were significantly higher in AP complicating plateau erythrocythemia compared with AP patients without complicating plateau erythrocythemia [ALT: (160.70 + or - 19.14) U/L vs. (78.00 + or - 14.96) U/L, Cr: (135.45 + or - 11.99) micromol/L vs. (91.42 + or - 17.08) micromol/L, both P<0.05]. Arterial partial pressure of oxygen (PaO(2)) and arterial oxygen saturation (SaO(2)) were significantly lower in AP with complication of plateau erythrocythemia than in AP without complicating plateau erythrocythemia [PaO(2): (45.10 + or - 0.40) mm Hg vs. (65.48 + or - 1.36) mm Hg, 1 mm Hg=0.133 kPa, SaO(2): 0.851 + or - 0.004 vs. 0.940 + or - 0.009, both P<0.05]. There was no difference in aspartate aminotransferase (AST), blood urea nitrogen (BUN) and arterial partial pressure of carbon dioxide (PaCO(2)), however, their levels were higher in plateau erythrocythemia cases than those without plateau erythrocythemia [AST: (87.35 + or - 8.10) U/L vs. (83.00 + or - 18.61) U/L, BUN:(10.90 + or - 0.97) mmol/L vs. (7.37 + or - 0.98) mmol/L, PaCO(2): (33.20 + or - 0.31) mm Hg vs. (25.32 + or - 1.14) mm Hg , all P>0.05]. ALT and Cr were significantly higher in high altitude cases than those in lower altitude cases [ALT: (126.92 + or - 15.46) U/L vs. (86.00 + or - 10.23) U/L, Cr:(126.10 + or - 10.01)micromol/L vs. (101.84 + or - 5.46) micromol/L, both P<0.05]. There was no difference in AST, BUN and PaCO(2), however, the values were slightly higher in high altitude cases compared with lower altitude cases [AST: (98.70 + or - 8.10) U/L vs. (93.14 + or - 21.46) U/L, BUN: (8.15 + or - 1.00) mmol/L vs. (5.86 + or - 0.40) mmol/L, PaCO(2): (32.32 + or - 1.01) mm Hg vs. (30.12 + or - 2.76) mm Hg, all P>0.05]. There was no difference in PaO(2) and SaO(2), however, it was slightly lower in high altitude cases than lower altitude cases [PaO(2): (58.80 + or - 1.20) mm Hg vs. (66.86 + or - 3.20) mm Hg, SaO(2): 0.910 + or - 0.011 vs. 0.930 + or - 0.008, both P>0.05]. The results showed that the deterioration of hepatic, kidney and lung function in AP patients living in the plateau was related to high altitude and erythrocythemia.

Non-invasive positive pressure ventilation in patients with acute hypoxemic respiratory failure: a prospective cohort study

To investigate the clinical effect of non-invasive positive pressure ventilation (NPPV) on acute hypoxemic respiratory failure (AHRF), and to look for predictors of failure of NPPV in patients with AHRF. In the cohort study, the clinical data of patients with AHRF in respiratory intensive care unit (RICU) of Beijing Chaoyang Hospital from January 2004 to December 2007 were collected prospectively. Patients were divided into successful group and failure group according to outcome of NPPV. Basic clinical information, NPPV mode and duration, vital signs, arterial blood gas analysis, and oxygenation index (PaO(2)/FiO(2)) before and 2 hours, 24 hours after NPPV were analyzed and compared between two groups. (1)The NPPV successful rate in 59 cases was 62.7% (37/59). (2)Compared with failure group, mean age, the ratio of patients in whom respiratory failure were induced by pulmonary infection were lower in successful group (both P<0.01). There was no difference in PaO(2)/FiO(2)between two groups before NPPV, but PaO(2)/FiO(2) in successful group was markedly higher than those of failure group after 2 hours and 24 hours of NPPV (P<0.05 and P<0.01), while heart rate (HR), respiratory rate (RR) were significantly lower (all P<0.01). (3)Logistic regression analysis identified age > or = 60 years [odds ratio (OR) 8.30, 95% confidence interval (CI) 2.49-27.60, P=0.002], pulmonary infection as underlying disease of respiratory failure (OR 6.19, 95%CI 1.90-20.20, P=0.027), PaO(2)/FiO(2)<150 mm Hg (1 mm Hg=0.133 kPa) after 2 hours of NPPV (OR 3.65, 95%CI 1.20-11.04, P=0.044), HR>100 times/min after 24 hours of NPPV (OR 7.45, 95%CI 2.15-25.58, P=0.010), and RR>30 times/min after 24 hours of NPPV (OR 7.26, 95%CI 1.88-24.49, P=0.018) as risk factors independently associated with failure of NPPV. NPPV can be the first line treatment for severe AHRF patients without absolute contraindication, while patients of older age with pulmonary infection, the risk of failure of NPPV is higher. Lack of improvement in cardiorespiratory and oxygenation condition after a short period of NPPV is the predictor of NPPV failure.

Modified Low-Flow Ultrafiltration Ameliorates Hemodynamics and Early Graft Function and Reduces Blood Loss in Living-Donor Lobar Lung Transplantation

This study analyzed the clinical application of modified low-flow ultrafiltration (MUF) to minimize cardiopulmonary bypass (CPB)-related adverse effects in patients undergoing living-donor lobar lung transplantation (LDLLT). The study enrolled 33 consecutive patients who underwent LDLLT from 1999 to 2004: 8 patients underwent conventional CPB without MUF (control group), and 15 underwent arteriovenous MUF (MUF-treated group). Hemodynamics, graft function, blood loss and blood transfusion requirements, and clinical outcomes were analyzed. There was a significant increase in systolic blood pressure and a decrease in pulmonary to systemic pressure ratio in the MUF-treated group (p < 0.05). No hemodynamic changes occurred in the control group. MUF resulted in significant improvements in arterial oxygen tension/fraction of inspired oxygen ratio (PaO(2)/FiO(2;) 411 +/- 107 vs 272 +/- 107 mm Hg, p < 0.05) and the alveolar-arterial oxygen difference (a-aDO(2); 158 +/- 84 vs 315 +/- 127 mm Hg, p < 0.05) at 15 minutes after CPB. There were no differences in PaO(2)/FiO(2) and A-aDO(2) between the groups beyond 6 hours post-operatively. Post-operative blood loss and blood transfusion requirements were lower in the MUF-treated group than in the control group (p < 0.05). There were no differences in survival, duration of ventilation, intensive care unit stay, and hospital stay between the groups. The low-flow MUF brought improved hemodynamics and gas exchange capacity of transplanted grafts and lowered post-operative blood loss and blood transfusion requirement. This strategy may minimize CPB-related adverse effects in patients undergoing LDLLT.

Preserving Oxygenation during Walking in Severe Chronic Obstructive Pulmonary Disease: Noninvasive Ventilation versus Oxygen Therapy

Background: Physical activity is known to cause significant deoxygenation in patients with severe chronic obstructive pulmonary disease (COPD). Although noninvasive positive pressure ventilation (NPPV) has been shown to improve oxygenation and physical activity in these patients, no practical approach for the application of NPPV during walking has yet been established. Objective: To elucidate the most effective approach to preserving oxygenation during walking in patients with severe COPD receiving long-term NPPV. Methods: Three 12-min walking tests were performed in a randomized cross-over design on 3 consecutive days, comparing the usual and double dosages of oxygen versus NPPV plus the usual dosage of oxygen. The ventilator and oxygen tank were placed in a backpack. Results: Eleven patients (FEV₁ 26 ± 9% predicted) completed the study, while 8 patients refused to walk with NPPV, due to the weight of the ventilatory device (7.3 kg with NPPV vs. 3.1 kg without). PaO₂ changes during walking differed [p = 0.01, repeated-measures (RM)-ANOVA], whereas dyspnea was unchanged. The difference in PaO₂ change was 14.0 ± 16.6 mm Hg (unadjusted p = 0.0036, critical level = 0.017, RM-ANOVA) in favor of NPPV compared to the usual dosage of oxygen. Changes in FEV₁, tidal volume and inspiratory impedance were in favor of NPPV-aided exercise (all p < 0.05, RM-ANOVA). Walking distance was reduced under NPPV (555 ± 227 m) compared to the usual (619 ± 210 m) and double (622 ± 215 m) dosages of oxygen (p = 0.024, RM-ANOVA). Conclusions: NPPV plus supplemental oxygen, but not oxygen alone, preserves oxygenation during walking in patients with severe COPD. However, dyspnea and walking distance were not improved due to the burden of carrying the heavy ventilatory equipment in a backpack.

The effect of pentoxifylline on oxidative stress in CO2 pneumoperitoneum

Carbon dioxide (CO(2)) pneumoperitoneum induces peritoneal oxidative stress. This experimental, randomized, controlled study was designed to investigate the effect of pentoxifylline on oxidative stress induced by CO(2 )pneumoperitoneum. For this study, 36 Swiss albino rats were randomized into three groups. Arteria, vena femoralis, and peritoneal cavity were cannulated after anesthesia. The arterial pH, partial arterial oxygen pressure (PaO(2)), venous PO(2), arterial and venous PO(2) difference (P((a-v))O(2)), serum aspartate aminotransferase (AST), serum alanine aminotransferase (ALT), and thiobarbituric acid-reactive substances (TBARS) were studied at the end of the first and second hours in group 1 (control). In group 2, 1 cc isotonic NaCl was injected into peritoneal cavity and then CO(2) pneumoperitoneum was established. At the end of the first hour of insufflation and one hour after desufflation, the same parameters as in group 1 were studied. In group 3, the CO(2) pneumoperitoneum plus pentoxifylline group, all procedures as in group 2 were repeated, with the exception of pentoxifylline (50 mg/kg) injected in place of saline. At the end of the first hour, P((a-v))O(2 )value in group 2 was significantly less than in the control group (group 1) and group 3 (p \ 0.05). There were no significant differences in PaO(2, )pH, AST, and ALT values between groups (p [ 0.05). TBARS level in group 1 was significantly lower than in the other groups, but there was no significant difference in TBARS level between groups 2 and 3. At the end of the second hour, TBARS level in group 3 was significantly lower than in group 2 (p \ 0.05). Pentoxifylline may reduce the oxidative injury following laparoscopic procedures.

ESOMEPRAZOLE 40 MG ADMINISTERED INTRAVENOUSLY (I.V.) PROVIDES BETTER CONTROL OF BASAL AND STIMULATED GASTRIC ACID SECRETION THAN OMEPRAZOLE 40 MG ADMINISTERED I.V.

Purpose: This study compared the effect on basal and pentagastrin stimulated acid output (BAO and PAO) of single-dose i.v. administration of esomeprazole 40 mg and omeprazole 40 mg. Methods: This was an open, randomized, two-way cross-over study in 23 Helicobacter pylori-negative healthy male and female subjects (18 males; mean age: 26 years; mean body mass index: 22.8 kg/m). Both drugs were administered as single 30-minute i.v. infusions with a washout period of at least 6 days. BAO (1 h) and PAO (1.5 hrs) were determined at baseline, between 3–5.5 h and finally between 23–25.5 h after drug administration on each study day. Blood samples, taken during the first 12 hours, were used to determine the area under the plasma concentration-time curve (AUC) and maximum observed plasma concentration (Cmax) for both drugs. The PAO and BAO values were analyzed using a mixed model ANOVA. The mean for each treatment and the mean treatment difference were estimated with 95% confidence intervals (CI). As an interim analysis was performed when 12 subjects had been included in the study, a 97.5% CI was calculated for the mean difference in PAO measured 3-5.5 hours after dose. Results: At baseline the mean BAO and PAO were 4.4 mmol/h (95% CI: 3.0 to 5.8) and 34.0 mmol/h (95% CI: 30.2 to 37.2), respectively. Intravenous administration of esomeprazole 40 mg resulted in a more pronounced reduction in BAO and PAO both measured 3–5.5 h and 23–25.5 h after dose compared with omeprazole 40 mg i.v. (Table). The geometric mean AUC and Cmax values were 36% and 18% higher, respectively, for esomeprazole 40 mg i.v. compared with omeprazole 40 mg i.v. There were no serious adverse events and both drugs were well tolerated.Table: Basal and pentagastrin stimulated acid output (BAO, PAO).Conclusions: Esomeprazole 40 mg i.v. provides faster and more complete control of basal and stimulated gastric acid secretion throughout the 24-hour period than omeprazole 40 mg i.v.

Effect of Body Position on PaO2 and PaCO2 during Pregnancy

Background: The body position may have an effect on gas exchange though the magnitude of this effect has not been studied thoroughly during the three trimesters of pregnancy. Objectives: This study analyzes the effect of body position change on arterial oxygen tension (PaO₂) and arterial carbon dioxide tension (PaCO₂) in healthy pregnant women. Methods: We examined 21 lung healthy pregnant women at the end of the first, second and third trimester of pregnancy. Blood was drawn from the radial artery first in the sitting and subsequently in the supine position. Peak expiratory flow rate was determined as well. Results: No statistically significant difference was detected between the mean values of PaO₂ in the supine and in the sitting position at the end of the first trimester. On the contrary, at the end of the second trimester the mean value of PaO₂ in the supine position was 92.39 ± 1.95 mm Hg, while in the sitting position the mean PaO₂ was 96.56 ± 1.83 mm Hg (p < 0.001). At the end of the third trimester the mean PaO₂ in the supine position was 90.48 ± 2.91 mm Hg while in the sitting position the mean PaO₂ was 97.48 ± 1.46 mm Hg (p < 0.001). Conclusions: According to our data we conclude that the statistically significant difference in PaO₂ in the sitting and supine positions clearly shows that the position needs to be considered both when attempting to establish reference values and when evaluating gas tensions at the end of pregnancy.

SCR1sLe(X) reduces lung allograft ischemia-reperfusion injury but does not ameliorate acute rejection.

Combined inhibition of complement and leukocyte adhesion by sCR1sLe(X) reduces lung allograft dysfunction up to 24 h. In the present study its effect on graft function and acute rejection was evaluated up to 5 days after experimental transplantation. Orthotopic single left lung transplantation was performed in 35 male rats (Brown Norway to Fischer 344) after a total ischemic time of 20 h. Two groups were assessed after 1, 3, and 5 days post-transplant, respectively (n=5 per group and time point): controls vs. recipients which received 10 mg/kg sCR1sLe(X) 15 min prior to reperfusion. In addition, five animals received 10 mg/kg per day sCR1sLe(X) for 5 days. For blood gas analysis of the graft, the contralateral lung was occluded for 5 min to assess graft function. Lung grafts were flushed, and histological grading was performed in blinded fashion according to the International Society for Heart and Lung Transplantation criteria. Graft PaO(2) in recipients treated with sCR1sLe(X) was superior on day 1 (383+/-118 vs. 56+/-15 mmHg; P<0.0001) and day 3 (446+/-48 vs. 231+/-108 mmHg; P<0.0001). Five days after transplantation, no difference in PaO(2) was found (61+/-28 vs. 83+/-31 mmHg; P=0.59). Repeated treatment with sCR1sLe(X) for 5 days did not improve PaO(2) (64+/-5 mmHg; P=0.65 vs. control; P=0.93 vs. sCR1sLe(X)). At any time point, there was no difference in the degree of rejection between groups. In this model sCR1sLe(X) provided marked improvement of graft function up to 3 days, but inhibition of both complement system and selectin dependent leukocyte adhesion failed to protect against acute rejection.

Effect of Body Position on Arterial Oxygen Tension in the Elderly

Background: It is well known that body position can have an effect on gas exchange though the magnitude of this effect has not been studied thoroughly in the elderly. Objectives: This study analyzes the effect body position change has on arterial oxygen tension (PaO₂) and arterial carbon dioxide tension (PaCO₂) in healthy elderly. Methods: We tested 46 ‘lung-healthy’ elderly, including 30 women and 16 men, 67–88 years of age. Blood was drawn from the radial artery first in the sitting position and subsequently in the supine position. Spirometry was performed. Results: Mean (SD) sitting PaO₂ was 10.53 kPa (1.22), whereas mean supine PaO₂ was 9.85 kPa (1.33). The difference between sitting and supine PaO₂ was 0.68 kPa (0.86) and was statistically significant. Sitting PaCO₂ was 5.06 kPa (0.47) and supine PaCO₂ was 5.05 kPa (0.54). The difference between sitting and supine PaO₂ correlated positively with FEV₁/FVC %, negatively with the corresponding difference between sitting and supine PaCO₂,and negatively with BMI. Conclusions: We conclude that the significant difference in PaO₂ in sitting and supine positions clearly shows that the position needs to be considered both when attempting to establish reference values and when evaluating gas exchange in elderly persons. The positional changes in oxygenation are related to the corresponding change in PaCO₂, and to FEV₁/FVC % and BMI.

Effect of body position on gas exchange in patients with unilateral pleural effusion: influence of effusion volume

The objective of this study was to evaluate the effect of lateral body position on gas exchange in patients with unilateral pleural effusion, with special reference to the influence of effusion volume. Thirty consecutive patients with unilateral pleural effusion, without evidence of parenchymal pulmonary involvement, were entered into the study. Arterial blood gas tensions ( PaO 2, PaCO 2) were randomly measured in both right and left lateral decubitus body positions, while breathing room air. To assess the influence of the effusion volume, roentgenographic and functional parameters were used. Among the latter, FVC, FEV 1, TLC and RV were determined. The influence of the presence or absence of pleuritic pain on gas exchange was also assessed. There was no significant difference in PaCO 2 between right and left lateral decubitus body positions (31·1 ± 4·2 vs. 31·0 ± 4·5 mmHg). The differences in PaO 2 between the two body positions ranged from 0·5–2·5 mmHg (mean 9·3 ± 6·6 mmHg). Mean PaO 2 with the normal-side (control) down ( PaO 2-N) (81·4 ± 8·5 mmHg) was higher, but without significant statistical difference, than mean PaO 2 with the effusion-side down ( PaO 2-E) (78·0 ± 12·5 mmHg). PaO 2-N was higher than PaO 2-E in 22 of 30 patients (conventional), and lower in eight patients (paradoxical). No consistent relationship was found for alterations in PaO 2 in different positions with the volume of effusion, either when estimated by a roentgenographic method or when using spirometric or plethysmographic values. The mean difference between PaO 2 values in the two positions ( ΔPaO 2 N-E) (6·3 ± 9·8 mmHg) in patients with chest pain was significantly greater ( P<0·05) than the ΔPaO 2 N-E in patients without pain (−3·3 ± 10·7 mmHg). Moreover, only pleuritic chest pain showed a significant statistical influence on ΔPaO 2 N-E, when all factors were analysed simultaneously. Although gas exchange is improved in most patients in the lateral decubitus position with normal-side down, some patients behave paradoxically. This difference does not appear to be related to the effusion volume, but seems to be influenced by the presence of pleural pain.

Particules lipidiques intramacrophagiques recueillies par lavage bronchoalvéolaire : fréquence et intérêt diagnostique

This study aimed to determine the incidence and diagnostic value of fat-laden alveolar macrophages obtained by bronchoalveolar lavage (BAL). In 128 patients, including 66 patients admitted for multiple trauma, 158 BAL were carried out. However, 41 BAL from 32 patients were excluded because of poor quality of samples (not enough macrophages, too many ciliated cells, or haemorrhage). All the patients were intubated and mechanically ventilated, having pulmonary infiltrates on the chest film. BAL samples were examined after staining with oil-red-O. They were considered to be positive when more than 5 % of alveolar macrophages contained fat droplets. Among them 14 out of 47 patients (30 %) without multiple trauma were positive ; 7/14 had never been given any intravenous lipid infusion, and 5/14 had aspiration pneumonia (as opposed to 3/32 patients with negative BAL). Further 27 patients out of the 49 (55 %) with multiple trauma were positive. Among them 10/49 had clinical evidence of fat embolism, however, only 7/10 had positive samples. All these last ten patients had been given intravenous lipid infusions. The rate of positive alveolar macrophages was correlated neither with the plasma triglyceride concentration, nor the Fracture Index Score, nor the delay between the end of the lipid infusion and the BAL. There was no significant difference in PaO 2/ Fio 2 ratio between the patients with positive and negative BAL. Positive BAL was significantly associated with lipid infusions. The data therefore suggest that the presence of fat-laden alveolar macrophages are associated with various pathological pulmonary conditions, particularly aspiration pneumonia and lipid infusions. In the polytrauma patient with fat embolism, alveolar fat droplets is a common event which cannot be considered as pathognomonic because of numerous false positives in mechanically ventilated patients.

Exercise-induced arterial hypoxaemia in healthy human subjects at sea level.

We determined the incidence of exercise-induced arterial hypoxaemia and its determinants in sixteen highly trained, healthy runners who were capable of achieving and sustaining very high metabolic rates (maximal O2 uptake = 72 +/- 2 ml kg-1 min-1 or 4.81 +/- 0.13 l min-1). Arterial blood gases and acid-base status were determined at each load of a progressive short-term exercise test and repeatedly during constant-load treadmill running while breathing air and during inhalation of mildly hypoxic, hyperoxic, and helium-enriched gases. Three types of responses to heavy and maximum exercise were evident and highly reproducible within subjects. Four runners maintained arterial PO2 (Pa, O2) within 10 mmHg of resting values, another four showed 10-15 mmHg reductions in Pa, O2, and the remaining eight showed reductions of 21-35 mmHg, i.e. in all cases to a Pa, O2 of less than 75 mmHg and to less than 60 mmHg in two cases. During constant-load exercise, Pa, O2 was often maintained during the initial 30 s when hyperventilation was greatest; then hypoxaemia occurred and in most cases was either maintained or worsened over the ensuing 3-4 min. The most severe hypoxaemia during heavy exercise was associated with no or little alveolar hyperventilation (Pa, CO2 greater than 35 mmHg and PA, O2 less than 110 mmHg) and an alveolar to arterial PO2 difference [(A-a)DO2] in excess of 40 mmHg. During 3-4 min of heavy exercise alveolar PO2 (PA, O2) decreased by 20 mmHg in mild hypoxia (0.17 FI, O2; inspired % O2) and increased by 20 mmHg during mild hyperoxia (0.24 FI, O2) and 10 mmHg during the hyperventilation which accompanied normoxic helium breathing. In all cases Pa, O2 changed in proportion to PA, O2 with no consistent change in the alveolar to arterial PO2 difference [(A-a)DO2]. In view of the correction of hypoxaemia with mild hyperoxia and the very high ratios of alveolar ventilation to pulmonary blood flow (VA/QC = 4-6) achieved during heavy exercise, we think it unlikely that non-uniformity of the VA/QC distribution or veno-arterial shunt could explain the hypoxaemia observed in most of our subjects. By exclusion, we suggest that hypoxaemia may be attributed to a diffusion limitation secondary to very short red cell transit times in at least a portion of the pulmonary circulation.(ABSTRACT TRUNCATED AT 400 WORDS)