Lower PaO2 Research Articles

Effect of PaO2 and social circumstances on outcomes in out-patient treatment of COPD exacerbations

The current British Thoracic Society guidelines on COPD recommend that patients with COPD exacerbations should be admitted to hospital if they either have partial pressure of arterial oxygen of <7.0 kilopascals (kPa) or if they are living alone. This study was carried out to see if either of these factors have any effect on the outcome in patients presenting with COPD exacerbation in the setting of well established COPD services. This study was to see if patients with PaO2 < 7.0 kPa or those living alone were readmitted more frequently or had higher mortality than other patients discharged through the same scheme. A retrospective analysis was carried out on 1078 patients with acute exacerbation of COPD who were discharged home through Wigan "hospital at home" scheme in the period between November 1999 and February 2004 prior to the introduction of the new guidelines. This study found that there was no statistically significant difference in the rates of readmissions in patients with low PaO2 or those living in adverse social circumstances compared to other groups of patients. The number of patients dying in this period was too small to analyse with adequate power. This study indicates that such patients can be safely managed at home in the context of well established COPD services.

Evaluation of the Oxygenation Ratio as Long-Term Prognostic Marker After Lung Transplantation

Objective We hypothesized that the arterial blood gas oxygen tension/fraction of inspired oxygen ratio (PaO 2/FiO 2) would prove to be useful as a mortality marker after lung transplantation (LT). The aims of this study were to define the prevalence of various ranges of PaO 2/FiO 2 during the first 24 hours after LT and to evaluate which measurement using the PaO 2/FiO 2 best correlates with mortality. Methods A retrospective study was performed that included all patients who underwent LT from 1997 to 2005. We collected PaO 2/FiO 2 ratios at 0, 12, and 24 hours after admission to the intensive care unit (ICU). We classified the 132 patients in 5 groups, based on PaO 2/FiO 2 (Group 1, PaO 2/FiO 2 <100; Group 2, PaO 2/FiO 2 100–199; Group 3, PaO 2/FiO 2 200–299; Group 4, PaO 2/FiO 2 300–399; Group 5, PaO 2/FiO 2 ≥400). The correlation between PaO 2/FiO 2 and mortality was studied using Cox regression. Results Cox regression analysis showed that PaO 2/FiO 2 at 0 and 12 hours after admission to the ICU were not useful mortality markers. However, the PaO 2/FiO 2 at 24 hours after admission to the ICU was a useful long-term prognostic marker. PaO 2/FiO 2 >100 (groups 2, 3, 4, and 5) at 24 hours was significantly associated with less mortality when a lower PaO 2/FiO 2 was the reference (hazard Ratio: 0.08, 0.02, 0.05, and 0.02, respectively). On multivariate analysis PaO 2/FiO 2 ≥100 (groups 2, 3, 4, and 5) at 24 hours was significantly associated with less mortality when a lower PaO 2/FiO 2 was the reference (hazard ratio: 0.07, 0.003, 0.01, and 0.005, respectively). Conclusions A value of PaO 2/FiO 2 >100 mm Hg 24 hours after admission to the ICU is associated with a lower mortality.

Correlation between High-Resolution Computed Tomography Findings and Lung Function in Pulmonary Langerhans Cell Histiocytosis

Background: Pulmonary Langerhans cell histiocytosis (PLCH) is an uncommon interstitial lung disease which can lead to serious respiratory failure. The correlation between high-resolution computed tomography (HRCT) findings and lung function have not been studied in depth. Objectives: To assess the relationship between HRCT findings and lung function in PLCH. Methods: Since HRCT abnormalities in PLCH consist mainly of nodular opacities and cystic abnormalities, we determined semiquantitative scores of nodular profusion and cystic extent. We therefore assessed the relationship between HRCT abnormalities on one hand and lung function and gas exchange parameters on the other, in patients with PLCH. Results: In our series of 26 consecutive patients, we found no significant correlation between the score of nodular profusion and lung function or gas exchange parameters. The score of cystic extent showed a quite strong and significant correlation with FEV₁/FVC (r = –0.62; p = 0.01), but also with PaO₂ (r = –0.69; p = 0.001) and carbon monoxide diffusing capacity (r = –0.60; p < 0.01). Furthermore, the patients with a predominant cystic pattern (n = 7) had the highest grade of dyspnea on exertion (p = 0.004), the lowest FEV₁/FVC ratio (p = 0.02) and the lowest PaO₂ (p = 0.02) compared to patients with a predominant nodular (n = 12) or a mixed pattern (n = 7). Conclusions: We conclude that in PLCH, the cystic extent on HRCT, but not the nodular profusion, correlates significantly with lung function abnormalities and impairment of gas exchange.

Pertussis: Severe clinical presentation in pediatric intensive care and its relation to outcome*

To describe our institutional experience in the management of infants and children with pertussis admitted during a 20-yr period (January 1985 through December 2004) and also to study the relation between method of presentation and outcome. Pediatric intensive care unit in a university-affiliated tertiary pediatric hospital in Melbourne, Australia. Retrospective review of medical records and radiology reports of patients with a diagnosis of pertussis identified from the pediatric intensive care unit database. A total of 49 patients (median age, 6 wks; interquartile range, 4-8 wks) required 55 admission episodes to the pediatric intensive care unit. Main reasons for admission were apnea with or without cough paroxysms (63%), pneumonia (18%), and seizures (10%). None of the infants had completed the primary course of immunization, and 94% had not received a single dose of pertussis vaccine. Infants presenting with pneumonia presented earlier (p = .001), had longer intensive care stay (p = .007), higher white cell count (p < or = .001), lower Pao2 at admission (p = .020), and higher mortality. Six infants out of seven needing circulatory support died (including all four treated with extracorporeal membrane oxygenation), and all deaths (n = 7) occurred in infants who had pneumonia at presentation. Patients with pertussis, presenting as apnea (with or without cough paroxysms), treated in the pediatric intensive care unit had 100% survival. However, pneumonia as the main reason for admission and the need for circulatory support is associated with a very poor outcome. A deeper understanding of the molecular basis of Bordetella pertussis and its relation to the human host might offer means for future therapies.

Are multiple blood transfusions really a cause of acute respiratory distress syndrome?

Multiple blood transfusions are considered a common cause of acute respiratory distress syndrome (ARDS). We hypothesized that ARDS is more a consequence of ARDS risk factors (in particular circulatory shock) requiring transfusions than a result of the transfusions themselves. This retrospective study included 103 patients admitted during a 10-month period to an 858-bed university hospital who received multiple transfusions (more than six units of packed red blood cells in 24 h). Ten patients developed ARDS; they were more commonly admitted with circulatory shock (36 (38.7%) vs. 8 (80%), P = 0.01), polytrauma (7 (7.5%) vs. 4 (40%), P = 0.01) or thoracic trauma (3 (3.2%) vs. 4 (40%), P = 0.01). The sequential organ-failure assessment (SOFA) score at admission was higher in patients who developed ARDS than in those who did not (9.0 +/- 3.1 vs. 5.6 +/- 3.4, P < 0.005). The total amount of transfusion in the first 24 h was 14.0 +/- 6.8 U in the ARDS patients and 10.6 +/- 7.3 U in the other patients (P = 0.17); the differences remained non-significant in the following days. During the first 24 h, patients who developed ARDS received more fresh frozen plasma than those who did not (21.8 +/- 10.6 U vs. 10.7 +/- 14.7 U, P = 0.02). Patients who developed ARDS had lower PaO2/FiO2 ratios (114 +/- 61 mmHg vs. 276 +/- 108 mmHg, P = 0.01), lower arterial pH (7.27 +/- 0.10 vs. 7.34 +/- 0.11, P = 0.06) and higher minute volume (10.6 +/- 2.8 L min(-1) vs. 7.9 +/- 1.8 L min(-1), P = 0.03) than patients without ARDS. Multivariable analysis retained thoracic trauma and hypoxaemia during the first 24 h (but not multiple transfusions) as independent risk factors for ARDS. In this retrospective study, the development of ARDS in massively transfused patients was less related to poly-transfusion than to other factors related to circulatory shock, polytrauma or thoracic trauma. Thoracic trauma and a low PaO2 during the first 24 h were identified as independent risk factors for ARDS.

LEVELS OF SPO2 BETWEEN 85% AND 93% ARE ASSOCIATED WITH NORMOXEMIA IN NEWBORNS RECEIVING OXYGEN THERAPY (FIO2 &gt; 0.21) IN THE NEONATAL INTENSIVE CARE UNIT.

Introduction Newborns (NBs) breathing room air (RA) have normal SpO2 of 95 to 100% but keeping SpO2 95 to 100% in NB breathing FiO2 > 0.21 can cause hyperoxia. In 2003 and 2006, we reported that SpO2 85 to 95% is associated with less morbidity. There is concern that these SpO2 levels may cause persistent or intermittent hypoxemia. Objective To evaluate PaO2 at different SpO2 levels in NBs with arterial catheters. Methods Prospective comparison of PaO2 and SpO2 in stable NB in six NICUs located at sea level in two countries. PaO2 was obtained for clinical indications; simultaneous SpO2 was recorded at the time of the arterial gas. Comparisons were made only in stable NBs if the SpO2 changed Results 674 paired SpO2 values in 85 NBs; 20% of the samples when NBs in RA. GA and BW: 30.5 ± 5.3 w and 1,516 ± 910 g. NBs in RA: Mean and median SpO2 were 94.6% ± 4.3 and 96% (73-100%); with SpO2 85 to 93%, mean PaO2 was 59.4 ± 15.9 mm Hg. When SpO2 > 93%, mean PaO2 was 72.7± 24.7 mm Hg. NBs breathing FiO2 > 0.21: (a) With SpO2 85 to 93%, mean PaO2 was 60 ± 16.7 mm Hg, median 56 mm Hg (29-112); PaO2 of 40 to 80 mm Hg in > 79% of samples, and PaO2 93%, mean PaO2 was 122.7 ± 62.9 mm Hg, median 110 mm Hg (38-438) (p ≤ .001 vs infants with SpO2 85-93%); 72% of the PaO2 values were > 80 mm Hg and 27% between 40 and 80 mm Hg. Conclusions NBs breathing FiO2 > 0.21: (1) Normoxemia is much more frequent with SpO2 85 to 93% than with SpO2 > 93%; (2) SpO2 85 to 93% avoids abnormally high PaO2 and is infrequently associated with low PaO2; (3) SpO2 > 93% is associated with hyperoxia, which may be of risk in some NBs receiving FiO2 > 0.21.

The Characteristics of Colorectal Cancer in Patients Older than 80 Years

Purpose: The frequency of surgery for elderly Koreans with colorectal cancer has increased because of the current life expectancy rates. The purpose of this study is to identify the characteristics of colorectal cancer in very elderly patients, to determine the optimal treatment decision, and to evaluate the patients prognosis. Methods: Between 1989∼2005, 181 patients (96 men and 85 women, median age 82) over the age of 80 with colorectal cancer underwent surgery at OO hospital, Korea. Medical records with these patients’ co-morbidities, symptoms, clinico-pathologic characteristics, complications, survival, and other relevant data were obtained and analyzed retrospectively. Results: The principal clinical symptoms were bleeding (45.3%) and bowel habit change (40.9%). Of these patients, 126 had at least one preoperative co-morbidity, and hypertension (29.3%), and cardiac disease (16.0%) were common. Curative surgery was performed in 82.9% (n=150). Emergency surgery was performed in 6.1% (n=11), and the principal cause was obstruction. The most common location of the colorectal cancer was the rectum (39.8%). There were postoperative complications in 36.4% of the patients, including voiding difficulty (12.2%) and wound infection (9.9%). The thirty-day mortality rate was 0.6% (n=1). A preoperative, low PaO2 level significantly increased the incidence of postoperative complications (P=0.036). The five-year survival rate of the curative resection group was higher than that in the remaining patients (44.3% vs. 38.8%, P＜0.001). Conclusions: Although the preoperative morbidity was high in these very elderly patients, it could be lowered with strict patient management. In addition, these patients showed a relatively good survival rate. Therefore, we believe that major, curative, colorectal surgery should be performed in selected very elderly patients.

Hypercyanotic spell after general anesthesia in Tetralogy of Fallot

A 21-year-old woman with tetralogy of Fallot referred because of a right temporo-occipital abscess, 2-months history of progressive visual loss, and headache. She had history of multiple drainages of brain abscesses and a Blalock-Taussing shunt, which was failed. With general anesthesia (GA) she underwent a temporo-occipital craniotomy and en-block removal of abscess. After termination of GA, she experienced two generalized seizures and became unconscious, tachycardia, and respiratory distress. The ABG showed low PaO2 and low pH. The respiratory distress was controlled by propranolol. When hypercyanotic spell occurs during anesthesia or early postoperative period, could cause serious problems for diagnosis and treatment.

Effect of pentoxifylline on lung inflammation and gas exchange in a sepsis-induced acute lung injury model

Experimental models of sepsis-induced pulmonary alterations are important for the study of pathogenesis and for potential intervention therapies. The objective of the present study was to characterize lung dysfunction (low PaO2 and high PaCO2, and increased cellular infiltration, protein extravasation, and malondialdehyde (MDA) production assessed in bronchoalveolar lavage) in a sepsis model consisting of intraperitoneal (ip) injection of Escherichia coli and the protective effects of pentoxifylline (PTX). Male Wistar rats (weighing between 270 and 350 g) were injected ip with 10(7) or 10(9) CFU/100 g body weight or saline and samples were collected 2, 6, 12, and 24 h later (N = 5 each group). PaO2, PaCO2 and pH were measured in blood, and cellular influx, protein extravasation and MDA concentration were measured in bronchoalveolar lavage. In a second set of experiments either PTX or saline was administered 1 h prior to E. coli ip injection (N = 5 each group) and the animals were observed for 6 h. Injection of 10(7) or 10(9) CFU/100 g body weight of E. coli induced acidosis, hypoxemia, and hypercapnia. An increased (P < 0.05) cell influx was observed in bronchoalveolar lavage, with a predominance of neutrophils. Total protein and MDA concentrations were also higher (P < 0.05) in the septic groups compared to control. A higher tumor necrosis factor-alpha (P < 0.05) concentration was also found in these animals. Changes in all parameters were more pronounced with the higher bacterial inoculum. PTX administered prior to sepsis reduced (P < 0.05) most functional alterations. These data show that an E. coli ip inoculum is a good model for the induction of lung dysfunction in sepsis, and suitable for studies of therapeutic interventions.

Early Procoagulant Shift in the Bronchoalveolar Compartment of Patients with Secondary Peritonitis

In acute respiratory distress syndrome or pneumonia, a procoagulant shift is observed in bronchoalveolar lavage fluid (BALF). The effect of a primarily extrapulmonary infection on coagulation and fibrinolysis in the pulmonary compartment is unclear. In 35 patients, 87 bronchoalveolar lavages were performed on the day of operation for secondary peritonitis (day 0) and on days 2 and 3 after surgery. Two noninfectious control groups were included: subjects undergoing bronchoalveolar lavage after elective surgery (n=8) and those undergoing long-term mechanical ventilation (n=10). In BALF from patients with peritonitis, a tissue factor (TF)/factor VIIa-mediated activation of coagulation was shown (high levels of thrombin-antithrombin complexes). Levels of fibrinolysis activators decreased rapidly after day 0, whereas levels of inhibitors increased. The net effect was reduced fibrinolysis (plasminogen activator activity). The sequential comparison of plasma levels of TF pathway inhibitor showed higher levels in patients who died (28-day mortality; P<.001). Sequential levels of TF in BALF were higher in patients with low PaO2 : FiO2 ratios (<200; P=.039). Differences between patients and control subjects were more pronounced in BALF than in plasma. Secondary peritonitis induces an early activation of the coagulation and inhibition of fibrinolysis in the systemic and bronchoalveolar compartments, possibly via a compartmentalized response. This imbalance may be associated with reduced oxygen delivery and an adverse outcome in secondary peritonitis.

Morphine administration in horses anaesthetized for upper respiratory tract surgery

ObjectiveTo determine the effect of morphine administration on commonly monitored cardio-respiratory variables and recovery quality in horses undergoing anaesthesia and surgery. Study designProspective, randomized clinical study. AnimalsThirty-eight thoroughbred horses, 32 geldings and six mares, 3–13 years old, weighing 411–600 kg. Materials and methodsA standard anaesthetic technique was used. Twenty minutes after induction of anaesthesia horses received 0.1 mg kg−1 (0.1 m) or 0.2 mg kg−1 (0.2 m) morphine by intravenous injection. A control group did not receive morphine. Heart rate, respiratory rate (fr), mean arterial pressure (MAP) and blood gases were measured before morphine administration and every 10 minutes thereafter. Horses were positioned for 35 minutes in right lateral recumbency for tension palatoplasty by cautery and were then moved into dorsal recumbency for additional intraluminal surgery comprising one or more of aryepiglottic fold resection, sub-epiglottal mucosal resection, ventriculectomy and cordectomy. A subjective recovery score from 0 (worst) to 5 (best) was assigned by a single observer who was unaware of treatment group. Two-way repeated measures anova, one-way anova, Kruskal–Wallis test, Mann–Whitney test, Pearson and Spearman correlation coefficients, and chi-squared tests were used to analyse the data where appropriate. ResultsArterial partial pressure of oxygen (PaO2) decreased significantly over time and was significantly lower in horses that received morphine. One horse in the control group and two horses in each of the morphine groups had a PaO2 <13 kPa. No other significant cardiopulmonary effects were detected. Recovery scores [median (range)] were higher in morphine recipients: 4 (2–5) in 0.1 m, 4 (3–5) in 0.2 m compared with 3 (2–4) in the control group. Conclusions and Clinical relevanceThe lower PaO2 in morphine recipients did not appear to be of clinical significance in healthy horses because the number of horses with a low PaO2 was similar between groups. The quality of recovery was significantly better in morphine recipients. These results indicate that morphine may be considered for use in clinical cases although further work is required to assess the analgesic properties of the drug in this species.

Hepatopulmonary syndrome in patients with chronic liver disease: role of pulse oximetry

BackgroundHepatopulmonary syndrome (HPS) is a rare complication of liver diseases of different etiologies and may indicate a poor prognosis. Therefore, a simple non-invasive screening method to detect HPS would be highly desirable. In this study pulse oximetry was evaluated to identify patients with HPS.MethodsIn 316 consecutive patients with liver cirrhosis (n = 245), chronic hepatitis (n = 69) or non-cirrhotic portal hypertension (n = 2) arterial oxygen saturation (SaO2) was determined using a pulse oximeter. In patients with SaO2 ≤92% in supine position and/or a decrease of ≥4% after change from supine to upright position further diagnostic procedures were performed, including contrast-enhanced echocardiography and perfusion lung scan.ResultsSeventeen patients (5.4%) had a pathological SaO2. Four patients (1.3%) had HPS. HPS patients had a significant lower mean SaO2 in supine (89.7%, SD 5.4 vs. 96.0%, SD 2.3; p = 0.003) and upright position (84.3%, SD 5.0 vs. 96.0%, SD 2.4; p = 0.001) and had a lower mean PaO2 (56.2 mm Hg, SD 15.2 vs. 71.2 mm Hg, SD 20.2; p = 0.02) as compared to patients without HPS. The mean ΔSaO2 (difference between supine and upright position) was 5.50 (SD 7) in HPS patients compared to non-HPS patients who showed no change (p = 0.001). There was a strong correlation between shunt volume and the SaO2 values (R = -0.94).ConclusionArterial SaO2 determination in supine and upright position is a useful non-invasive screening test for HPS and correlates well with the intrapulmonary shunt volume.

Maintained inspiratory activity during proportional assist ventilation in surfactant-depleted cats early after surfactant instillation: phrenic nerve and pulmonary stretch receptor activity

BackgroundInspiratory activity is a prerequisite for successful application of patient triggered ventilation such as proportional assist ventilation (PAV). It has recently been reported that surfactant instillation increases the activity of slowly adapting pulmonary stretch receptors (PSRs) followed by a shorter inspiratory time (Sindelar et al, J Appl Physiol, 2005 [Epub ahead of print]). Changes in lung mechanics, as observed in preterm infants with respiratory distress syndrome and after surfactant treatment, might therefore influence the inspiratory activity when applying PAV early after surfactant treatment.ObjectiveTo investigate the regulation of breathing and ventilatory response in surfactant-depleted young cats during PAV and during continuous positive airway pressure (CPAP) early after surfactant instillation in relation to phrenic nerve activity (PNA) and the activity of PSRs.MethodsSeven anesthetized, endotracheally intubated young cats were exposed to periods of CPAP and PAV with the same end-expiratory pressure (0.2–0.5 kPa) before and after lung lavage and after surfactant instillation. PAV was set to compensate for 75% of the lung elastic recoil.ResultsTidal volume and respiratory rate were higher with lower PaCO2 and higher PaO2 during PAV than during CPAP both before and after surfactant instillation (p < 0.05; both conditions). As an indicator of breathing effort, esophageal deflection pressure and PNA were lower during PAV than during CPAP in both conditions (p < 0.02). Peak PSR activity was higher and occurred earlier during PAV than during CPAP (p < 0.01), and correlated linearly with PNA duration in all conditions studied (p < 0.001). The inspiratory time decreased as tidal volume increased when CPAP was changed to PAV, with the highest correlation observed after surfactant instillation (r = -0.769). No apneic periods could be observed.ConclusionPSR activity and the control of breathing are maintained during PAV in surfactant-depleted cats early after surfactant instillation, with a higher ventilatory response and a lower breathing effort than during CPAP.

The influence of butorphanol dose on characteristics of xylazine–butorphanol–propofol anesthesia in horses at altitude

ObjectiveTo characterize behavioral and physiological responses to short-term, unsupplemented intravenous (IV) anesthesia in healthy horses at high altitude (2240 m), and to test the hypothesis that the dose of butorphanol modifies the response of the horse to propofol anesthesia following xylazine pre-medication. Study designRandomized prospective butorphanol dose cross-over experimental design. AnimalsEight healthy horses, 13 ± 6 (mean ± SD) years of age, and weighing 523 ± 26 kg. MethodsEach horse was anesthetized three times with at least 3 weeks between each anesthesia. After collecting pre-drug data, xylazine (0.5 mg kg−1) was given IV. Five minutes later butorphanol was given IV according to a randomized order of three doses: 0.025, 0.05 and 0.075 mg kg−1. Five minutes later, anesthesia was induced with propofol, 2 mg kg−1 IV. Data on heart rate (HR) and respiratory rate (fr), mean arterial blood pressure, PaO2, PaCO2 and pHa were collected before, during and for 60 minutes following anesthesia, and quality of induction and recovery was scored. ResultsThe pre-drug values for the three butorphanol groups did not differ. The combined pre-drug values from the 24 studies were HR, 33 ± 7 beats minute−1; fr, 11 ± 3 breaths minute−1; PaO2, 67 ± 7 mmHg; PaCO2, 36 ± 4 mmHg; and pHa, 7.42 ± 0.04. Five minutes after anesthetic induction PaO2 decreased and PaCO2 increased 14.5 ± 7.7 and 5.1 ± 4.9 mmHg, respectively, but returned to pre-drug levels within 15 minutes of anesthetic recovery. There were no significant butorphanol dose-related differences in physiological results, anesthetic induction and recovery quality scores or recovery time. Conclusions and Clinical relevanceDose of butorphanol did not markedly influence study results. Notably, low PaO2 values related to geographic location of study and general anesthesia indicates a narrow margin of error for hypoxemia-related complications in anesthetized horses breathing unsupplemented air at high altitude.

Pretreatment with Simvastatin Reduces Lung Injury Related to Intestinal Ischemia-Reperfusion in Rats

In this rat model study we evaluated whether pretreatment with simvastatin affects the severity of acute lung injury caused by intestinal ischemia-reperfusion (I/R). Twenty-four animals were randomly allocated to three equal groups (sham, control, simvastatin). The simvastatin group was pretreated with simvastatin 10 mg x kg(-1) x day(-1) for 3 days, whereas the other groups received placebo. The simvastatin and control groups underwent 60 min of superior mesenteric artery occlusion and 90 min of reperfusion. Compared with the simvastatin group, the control group exhibited significantly more severe intestinal I/R-induced acute lung injury, as indicated by lower Pao2 and oxygen saturation (P = 0.01 and P = 0.005, respectively) and higher mean values for neutrophil infiltration of the lungs (P = 0.003), total lung histopathologic injury score (P = 0.003), lung wet-to-dry weight ratio (P = 0.009), and lung-tissue malondialdehyde levels (P = 0.016). The control and simvastatin groups had similar serum levels and similar bronchoalveolar lavage fluid levels of cytokines (interleukin-1, interleukin-6, and tumor necrosis factor-alpha) and P-selectin at all measurements, except for a significantly higher level of bronchoalveolar lavage fluid P-selectin in the control group (P = 0.006). Pretreatment with simvastatin reduces the severity of acute lung injury induced by intestinal I/R in rats.

Sustained low diffusing capacity in hepatopulmonary syndrome after liver transplantation

To study the presence of sustained low diffusing capacity (DL(CO)) after liver transplantation (LT) in patients with hepatopulmonary syndrome (HPS). Six patients with mild-to-severe HPS and 24 without HPS who underwent LT were prospectively followed before and after LT at mid-term (median, 15 mo). HPS patients were also assessed at long-tem (median, 86 mo). Before LT, HPS patients showed lower PaO(2) (71 +/- 8 mmHg), higher AaPO(2) (43 +/- 10 mmHg) and lower DL(CO) (54% +/- 9% predicted), due to a combination of moderate-to-severe ventilation-perfusion (V(A)/Q) imbalance, mild shunt and diffusion limitation, than non-HPS patients (94 +/- 4 mmHg and 19 +/- 3 mmHg, and 85% +/- 3% predicted, respectively) (P<0.05 each). Seven non-HPS patients had also reduced DL(CO) (70% +/- 4% predicted). At mid- and long-term after LT, compared to pre-LT, HPS patients normalized PaO(2) (91 +/- 3 mmHg and 87 +/- 5 mmHg), AaPO(2) (14 +/- 3 mmHg and 23 +/- 5 mmHg) and all V(A)/Q descriptors (P<0.05 each) without changes in DL(CO) (53% +/- 8% and 56% +/- 7% predicted, respectively). Post-LT DL(CO) in non-HPS patients with pre-LT low DL(CO) was unchanged (75% +/- 6% predicted). While complete V(A)/Q resolution in HPS indicates a reversible functional disturbance, sustained low DL(CO) after LT also present in some non-HPS patients, points to persistence of sub-clinical liver-induced pulmonary vascular changes.

High Mortality Rate After Extubation Failure After Pediatric Cardiac Surgery

The objective of this study was to evaluate the different causes of extubation failure and the consequent mortality rates in a pediatric population after cardiac surgery. We studied 184 consecutive patients with a median age of 9 months (range, 0-165). In 158 patients, extubation was successful (group A). Nine patients were reintubated for upper airway obstruction and finally extubated successfully (group B). Seventeen patients were reintubated for cardiorespiratory failure, finally leading to death in 11 of 17 patients (65%) (group C). Group B patients were younger and had a longer intubation period compared to group A patients. Group C patients had more reoperations (30% vs 4% in group A patients, p < 0.001), a lower PaO2 on admission at the intensive care unit as well as just prior to extubation, a lower base deficit before extubation, and needed more inotropic support during their stay in the intensive care unit. We conclude that extubation failure after pediatric cardiac surgery due to cardiorespiratory failure is a bad prognostic sign. Patients with high inotropic support and a low PaO2 prior to extubation are especially at risk and probably need careful evaluation before final extubation.

Prevalence and clinical significance of a patent foramen ovale in patients with chronic obstructive pulmonary disease

A patent foramen ovale (PFO) is not widely recognized as a factor contributing to hypoxemia in patients with chronic obstructive pulmonary disease (COPD). We therefore sought to clarify the prevalence and clinical significance of a PFO in patients with COPD, and to analyze the factors related to its occurrence. This study included 52 consecutive stable patients with COPD and 50 healthy controls. The demographic and clinical features of the study group were noted. To test for a PFO, standard and contrast transthoracic echocardiographic examinations were performed while resting and during the Valsalva maneuver (VM). Patients performed 6-min walking tests (6 MWT), and the distances traveled were measured. During VM, we detected a PFO in 23 COPD patients and 10 healthy controls (P<0.01). A PFO was detected while resting in 11 COPD patients, but in none of the controls (P=0.001). Comparison of multiple parameters between COPD patients with and without a PFO during VM did not reveal any clinically significant differences. When we compared COPD patients with and without a PFO during resting, however, we found that the former had longer durations of disease, lower PaO2 and SaO2, higher dyspnea scores, shorter distances walked during 6 MWT and higher desaturation rates (P<0.05). Logistic regression analysis showed that longer duration of disease, lower SaO2 and higher systolic pulmonary artery pressure were independent predictors of the occurrence of a PFO in resting COPD patients. The prevalence of a PFO is higher in patients with COPD than in healthy individuals. The presence of a PFO while resting may contribute significantly to the deterioration of arterial oxygenation and performance status. These findings indicate that a PFO may be a principle cause of hypoxemia in patients with COPD.

Exhaled nitric oxide during normoxic and hypoxic exercise in endurance athletes

Endogenous nitric oxide (NO) through its relaxing effect on smooth muscle cells may be involved in pulmonary gas exchange as well as in the modulation of the hypoxic pulmonary vasoconstriction. As athletes with exercise-induced hypoxaemia (EIH) present pulmonary gas exchange abnormalities in normoxia that could be even greater in hypoxia, we hypothesized that pulmonary NO may be lower in such athletes with EIH. Eleven athletes with EIH [decrease in arterial oxygen blood partial pressure (PaO2) > 12 mmHg] and 9 without EIH (NEIH) exercised at 40%, 60% (10 min) and 90% (5 min) of normoxic maximal power output (Pmax) in normoxia, and at 40% and 60% (10 min) of Pmax in hypoxia (FiO2 = 15%). Exhaled NO concentration during a constant flow exhalation (FENO(0.170)) and arterialized blood gases were measured at every power output. FENO(0.170) decreased from rest to exercise both in normoxia (-27.8 +/- 22.8% at 90% Pmax, P < 0.001) and hypoxia (-23.8 +/- 17.5% at 60% Pmax, P < 0.001). At 90% Pmax in normoxia, EIH athletes showed lower PaO2 (76.7 +/- 5.4 vs. 82.8 +/- 4.4 mmHg, P = 0.013) and greater FENO(0.170) decrement (-37.0 +/- 24.7% vs. -16.6 +/- 14.6%, P = 0.042) than NEIH athletes. During hypoxic exercise, P(a)O(2) and FENO(0.170) decreases were similar in both groups (P > 0.05). The present study shows lower pulmonary NO in athletes with gas exchange abnormalities during intense exercise in normoxia, while EIH and NEIH athletes have similar decreases in blood gases and pulmonary NO during hypoxic exercise. Decreased pulmonary NO in such conditions may contribute to ventilation-perfusion inequality and/or increase pulmonary vascular tone in athletes.

Relationship between hypoxic hepatitis and cor pulmonale in patients treated in the respiratory ICU*

To determine independent risk factors associated with the pathogenesis hypoxic hepatitis (HH) in hypoxemic patients. The prospective study, multivariate analysis, between January 1999 and March 2003 was conducted at University hospital, intensive care unit, Department of Chest Diseases. A total of 445 consecutive patients were included in the study. Patients who were not hypoxemic (PaO(2) > 80 mmHg) were excluded from analysis. The total number of those found eligible for the study was 297. Patients with a >20-fold increase in liver enzyme levels were diagnosed as HH (study group). The other patients were defined as control group. There were no interventions. Mean age was 62, and 191 were males. Twenty-two patients were diagnosed as HH (study group; 7.41%). Cor pulmonale (CP) was 77.3% in the study group and 36.7% in the control group. The need for mechanical ventilation and hospital mortality were 63.6 and 54.5% in the study group and 32 and 28.7% in the control group, respectively. On multivariate analysis, the presence of CP (p = 0.007; OR: 4.418; CI: 1.492-13.083), high-serum BUN level (>37 mg/dl; p = 0.0001; OR: 1.029; CI: 1.015-1.044) and low PaO(2) level (<46 mmHg; p = 0.008; OR: 0.945; CI: 0.906-0.985) were found to be significantly different between the two groups. Patients with severe hypoxemia, CP and higher BUN level have higher risk levels for HH, the most important risk factor being CP.