Latent environment allocation of microbial community data.

As data for microbial community structures found in various environments has increased, studies have examined the relationship between environmental labels given to retrieved microbial samples and their community structures. However, because environments continuously change over time and space, mixed states of some environments and its effects on community formation should be considered, instead of evaluating effects of discrete environmental categories. Here we applied a hierarchical Bayesian model to paired datasets containing more than 30,000 samples of microbial community structures and sample description documents. From the training results, we extracted latent environmental topics that associate co-occurring microbes with co-occurring word sets among samples. Topics are the core elements of environmental mixtures and the visualization of topic-based samples clarifies the connections of various environments. Based on the model training results, we developed a web application, LEA (Latent Environment Allocation), which provides the way to evaluate typicality and heterogeneity of microbial communities in newly obtained samples without confining environmental categories to be compared. Because topics link words and microbes, LEA also enables to search samples semantically related to the query out of 30,000 microbiome samples.

Effects of indigo carmine intravenous injection on oxygen reserve index (ORi™) measurement.

To retrospectively investigate the effects of indigo carmine intravenous injection on oxygen reserve index (ORi™) in 20 patients who underwent elective gynecologic surgery under general anesthesia. The study subjects were patients who underwent elective gynecologic surgery under general anesthesia between April 2016 and January 2017, and were administered a 5-ml intravenous injection of 0.4% indigo carmine for clinical purposes during surgery with ORi monitoring. Changes in ORi within 20 min after indigo carmine injection were observed. A relevant decrease in ORi was defined as ≥ 10% reduction in ORi from pre-injection level. ORi rapidly decreased after indigo carmine intravenous injection in all patients. In 10 of 19 patients, ORi decreased to 0 after indigo carmine injection. The median lowest value of ORi was 0 (range 0-0.16) and the median time to reach the lowest value of ORi was 2 min (range 1-4 min) after injection. ORi values returned to pre-injection levels within 20 min in 13 of 19 patients, and the median time to return to pre-injection levels was 10 min (range 6-16 min) after injection. During ORi monitoring it is necessary to consider the rapid reduction in ORi after intravenous injection of indigo carmine.

Effects of indigo carmine intravenous injection on noninvasive and continuous total hemoglobin measurement with using the Revision L sensor.

The effects of intravenous injection of indigo carmine on noninvasive and continuous total hemoglobin (SpHb) measurement were retrospectively evaluated with the Revision L sensor. The subjects were 18 patients who underwent elective gynecologic surgery under general anesthesia. During surgery, 5 mL of 0.4 % indigo carmine was injected intravenously, and changes in SpHb concentrations between before and after the injection were evaluated. The mean age was 52.4 ± 12.8 years. Before injection, the median SpHb level was 10.1 (range, 6.8-13.4) g/dL. The results demonstrated no change in SpHb concentration between before and after indigo carmine injection as detected by the Revision L sensor. SpHb measurements as determined with the Revision L sensor were not affected, even after the intravenous injection of indigo carmine.

Analysis of the sexual development-promoting region of Schizophyllum commune TRP1 gene.

This study aims to elucidate the mechanism of sexual development of basidiomycetous mushrooms from mating to fruit body formation. Sequencing analysis showed the TRP1 gene of basidiomycete Schizophyllum commune encoded an enzyme with three catalytic regions of GAT (glutamine amidotransferase), IGPS (indole-3-glycerol phosphate synthase), and PRAI (5-phosphoribosyl anthranilate isomerase); among these three regions, the trp1 mutant (Trp(-)) had a missense mutation (L→F) of a 338th amino acid residue of the TRP1 protein within the IGPS region. To investigate the function of IGPS region related to sexual development, dikaryons with high, usual, and no expression of the IGPS region of TRP1 gene were made. The dikaryotic mycelia with high expression of the IGPS formed mature fruit bodies earlier than those with usual and no expression of the IGPS. These results showed that the IGPS region in TRP1 gene promoted sexual development of S. commune.

Effects of indigo carmine intravenous injection on noninvasive and continuous total hemoglobin measurement.

The effects of an intravenous injection of indigo carmine on noninvasive and continuous total hemoglobin (SpHb) measurement were retrospectively evaluated. The subjects were 21 patients who underwent elective gynecologic surgery under general anesthesia. During surgery, 5 mL of 0.4 % indigo carmine was intravenously injected, and subsequent changes in SpHb concentrations were evaluated. The results demonstrate that the pre-injection SpHb level was 10 g/dL, and the minimum post-injection SpHb level was 8.3 g/dL. The amount of decrease was 1.8 g/dL. The time to reach the minimum value was 4 min, and the time to return to the pre-injection value was 15 min. The decrease in SpHb was greater in the group with a perfusion index (PI) < 1.4 than in the group with a PI > 1.4. The assessment of SpHb after an intravenous injection of indigo carmine necessitates caution.

Two cases of bilateral lung transplantation combined with intracardiac repair and pulmonary artery replacement: perioperative managements based on the left ventricular function.

We report on two patients who underwent bilateral lung transplantation (BLTx) combined with cardiac surgery. Patient 1 was a female whose pulmonary hypertension resulted from a congenital atrial septal defect (ASD) and idiopathic pulmonary arterial hypertension. She had a very small left ventricle (LV). We initiated venoarterial extracorporeal membrane oxygenation (ECMO) before induction of general anesthesia. She underwent ASD patch closure, pulmonary artery replacement, and BLTx under cardiopulmonary bypass (CPB). At the weaning from CPB, primary graft dysfunction and pulmonary edema induced by LV diastolic dysfunction was apparent. We gradually decreased the ECMO support and eventually weaned off the ECMO on the 4th postoperative day (POD) and the ventilator on the 29th POD. Patient 2 was a male with Eisenmenger syndrome, which resulted from ASD and ventricular septal defect (VSD). He had a normal LV. General anesthesia was induced smoothly without ECMO. He underwent ASD and VSD patch closure, pulmonary artery replacement, and BLTx under CPB. Weaning from CPB proceeded smoothly. These patients needed different management because of their different LV function. Especially, perioperative management of the BLTx patient with LV diastolic dysfunction was difficult. Assessment of perioperative cardiac function is very important in BLTx combined with cardiac surgery.

[Effects of Anesthetics on Perioperative Short-term Outcomes in Patients Undergoing Thoracic Surgery with One-lung Ventilation].

BACKGROUND: The present study was designed to evaluate the postoperative values such as body temperature (BT), white blood cells (WBC), P/F ratio and C-reactive protein (CRP) associated with propofol or sevoflurane in patients undergoing thoracic surgery with one-lung ventilation. METHODS: We retrospectively reviewed outcomes of patients undergoing video-associated thoracic surgery of the esophagus (VATS-E) with propofol (group P, n = 71) or sevoflurane (group S, n = 34). Data were taken at 1 POD and 2 POD in ICU. In addition, data of WBC and CRP were taken just before the operation and on 5 POD. Statistical analyses used t-value and two-way ANOVA with statistic significance as P < 0.05. RESULTS: There was no significant difference between the two groups and we could not find the correlation between anesthetics and each factor. CONCLUSIONS: Propofol and sevoflurane had similar effect on BT, WBC, P/F ratio and CRP in patients undergoing thoracic surgery with one-lung ventilation.

Glucocorticoid mediates the transcription of OAT-PG, a kidney-specific prostaglandin transporter.

OAT-PG is a kidney-specific prostaglandin transporter and exclusively expressed at the basolateral membrane of proximal tubules in rodent kidneys. We previously reported that OAT-PG was dominantly expressed in the male kidney similar to the other SLC22 family proteins as organic anion transporter (OAT) 1 and OAT3. Recently, Wegner et al. revealed that a transcription factor, B-cell CLL/lymphoma 6 (BCL6), is associated with the male-dominant expressions of OAT1 and OAT3 in the rat kidney. Here, we performed the luciferase assay to investigate whether OAT-PG is also transcriptionally regulated by BCL6. However, the promoter activity of OAT-PG was not directly affected by BCL6 overexpression nor the testosterone treatment, suggesting that different regulatory mechanisms underlie the male-dominant transcriptional regulation of OAT-PG compared to those of OAT1 and OAT3. We newly found that adrenalectomy (Adx) of male rat caused a significant reduction of OAT-PG expression without any significant changes in the OAT1 and OAT3 expressions, and it was recovered by the dexamethasone administration. Furthermore, the renocortical PGE2 concentration was markedly increased in Adx male rat, concomitant with the downregulation of OAT-PG, and it was reduced to the basal level by dexamethasone treatment. In the luciferase assay, dexamethasone stimulated OAT-PG promoter activity but not OAT1. The luciferase activity responsiveness to dexamethasone was significantly reduced by the deletion of glucocorticoid response elements in the OAT-PG promoter region. These results suggest that glucocorticoid plays an important role in the regulation of the renocortical PGE2 concentration by the transcriptional regulation of OAT-PG in the rat kidney.

Lower incidence of emergence agitation in children after propofol anesthesia compared with sevoflurane: a meta-analysis of randomized controlled trials.

BACKGROUND: Emergence agitation (EA) from general anesthesia has been reported as an adverse effect of sevoflurane in children. We describe a meta-analysis of randomized controlled trials that compared the incidence of EA between children who underwent sevoflurane anesthesia and those who underwent propofol anesthesia. METHODS: A literature search was conducted to identify clinical trials that met our inclusion criteria. Prospective randomized trials comparing sevoflurane and propofol anesthesia in children less than 15 years of age were included in the meta-analysis. Data from each trial were combined using the random effects model to calculate pooled odds ratios (ORs) and their corresponding 95 % confidence intervals (CIs). The heterogeneity of data was assessed by Cochran's Q and I (2) tests. Sensitivity analysis was conducted for study quality, patient age, and type of surgical procedure. RESULTS: The meta-analysis included 14 studies, in which 560 patients received sevoflurane and 548 received propofol. The pooled OR for EA was 0.25 with a 95 % CI of 0.16-0.39 (P = 0.000), which indicates that propofol anesthesia resulted in a lower incidence of EA. The heterogeneity of data was not statistically supported (P = 0.191). All sensitivity analyses strengthened the evidence for the lower incidence of EA with propofol. CONCLUSIONS: Our meta-analysis demonstrated that EA in children is less likely to occur after propofol anesthesia compared with sevoflurane anesthesia.

[Anesthetic management of six patients with surgically repaired tetralogy of Fallot undergoing the second intra-cardiac surgery].

In Japan, more than 9,000 patients with congenital heart disease reach adulthood every year with improved medical treatment, and perioperative encounter with patients requiring the second intra-cardiac operation in adulthood is more often. Tetralogy of Fallot (TOF) is the most common form of cyanotic congenital heart disease, and long-term prognosis is good. Therefore, we have more chances to care the postoperarive adult patients with TOF. This is a retrospective study in 6 patients with TOF who underwent the second intra-cardiac operation in adulthood from 2008 to 2012. Among the six patients, six had pulmonary valve replacement; four had tricuspid valve replacements or valvuloplastys; four had ventricular septal defect closures; two had right ventricular outflow tract obstruction releases; one had aortic valve replacement; and three had cryoablations. Right ventricular end-diastolic volume was 194.1 +/- 83.5 ml x m(-2) (mean +/- SD), and right ventricular ejection fraction was 38.2 +/- 4.8%. The factors which influence the anesthetic management were as follows: right cardiac failure by abnormality of the pulmonary valve; residual disease and deuteropathy of two or more combination; the risks associated with the second open chest surgery such as long operative time and severe bleeding. Perioperative management of an adult with congenital heart disease requires full understanding of its pathophysiology such as congenital heart disease, adult-specific complications, and the second open chest surgery.

Differences in the released endothelial microparticle subtypes between human pulmonary microvascular endothelial cells and aortic endothelial cells in vitro.

Circulating endothelial microparticles (EMPs) are membrane vesicles that are shed into the blood stream from activated or apoptotic endothelial cells. We previously reported that circulating EMP numbers significantly increased in stable chronic obstructive pulmonary disease (COPD) patients and during exacerbation compared with healthy control subjects. However, different types of circulating EMPs with distinct time profiles were detectable during exacerbations. We hypothesized that the released EMP subtypes correlated with differences in the inflammatory stimuli and the endothelial cell type. We compared the EMP subtypes from human aortic endothelial cells (Aortic ECs) and human lung microvascular endothelial cells (Pulmonary microvascular ECs) released in response to various stimuli, including proinflammatory cytokines (TNFα), oxidative stress (H2O2), and cigarette smoke extracts (CSE) in vitro. We defined circulating EMPs by the expression of endothelial antigens: CD144(+) MPs (VE-cadherin EMPs), CD31(+)/CD41(-) MPs (PECAM EMPs), CD62E(+) MPs (E-selectin EMPs), and CD146(+) MPs (MCAM EMPs). E-selectin EMPs were released from both pulmonary microvascular and aortic ECs in response to TNFα but not to H2O2 or CSE stimulation. The amount of MCAM EMPs released from pulmonary microvascular ECs differed significantly between the cells stimulated with H2O2 and those stimulated with CSE. VE-cadherin EMPs were only released from aortic ECs, whereas PECAM EMPs were released exclusively from pulmonary microvascular ECs. The EMP subtypes released differ in vitro among TNFα, H2O2, and CSE stimulation as well as between pulmonary microvascular and aortic ECs. The differences in circulating EMP subtypes may reflect a condition or site of endothelial injury and may serve as markers for endothelial damage in COPD patients.

Decreased expression of a novel prostaglandin transporter, OAT-PG, facilitates renocortical PGE2 accumulation during rat pregnancy.

BACKGROUND: Prostaglandin (PG)-specific organic anion transporter (OAT-PG) is a recently identified renal transporter involved in the local clearance of prostaglandin E2 (PGE2). Since the renal biosynthesis of PGE2 is not increased during pregnancy, this transporter expression would affect the gestational changes in the renal PGE2 content. METHODS: Kidneys from rats at different gestational stages were used to examine gestational changes in the renocortical PGE2 concentration. The renal expression of OAT-PG and the enzymes for PGE2 synthesis was also examined sequentially, together with the gestational changes in renal renin production. RESULTS: The renocortical PGE2 concentration was significantly increased during midterm to late pregnancy, with a maximum increase of 47.6 ± 11.5% from the virgin value. Although the expression of the enzymes, such as cyclooxygenases and PG synthases, was not increased, that of OAT-PG was significantly decreased throughout pregnancy, inversely correlating with changes in the renocortical PGE2 concentration. Renal renin production was significantly increased during pregnancy. CONCLUSION: This study demonstrated for the first time that the tissue PGE2 concentration was increased in pregnant rat kidneys, which may be associated with the gestational rise in glomerular filtration rate. The decreased expression of OAT-PG was thought to be responsible for the increased tissue PGE2 content.

Higher fraction of inspired oxygen in anesthesia induction does not affect functional residual capacity reduction after intubation: a comparative study of higher and lower oxygen concentration.

BACKGROUND: Low fraction of inspired oxygen (FIO2) reduces the atelectasis area during anesthesia induction. However, atelectasis may occur during laryngoscopy and endotracheal intubation because lungs can collapse within a fraction of a second. We assessed the effects of ventilation with 100 and 40 % oxygen on functional residual capacity (FRC) in patients undergoing general anesthesia. METHODS: Twenty patients scheduled for elective open abdominal surgery were randomized into 40 % oxygen (GI, n = 10) and 100 % oxygen (GII, n = 10) groups and FRC was measured. Preoxygenation and mask ventilation with 40 and 100 % oxygen were used in GI and GII, respectively. In both groups, 40 % oxygen was used for anesthesia maintenance after intubation. Bilateral lung ventilation was performed with volume guarantee and low tidal volume (7 ml/kg predicted body weight) using bilevel airway pressure. We measured FRC and blood gas in all patients during preoxygenation, after intubation, and during surgery. RESULTS: FRC decreased from during preoxygenation (GI 2380 ml, GII 2313 ml) to after intubation (GI 1569 ml, GII 1586 ml) and significantly decreased during surgery (GI 1338 ml, GII 1417 ml) (P < 0.05). PaO2/FIO2 decreased from during preoxygenation (GI 419 mmHg, GII 427 mmHg) to after intubation (GI 381 mmHg, GII 351 mmHg) and significantly decreased during surgery (GI 333 mmHg, GII 291 mmHg) (P < 0.05). No significant differences were found between the groups in both parameters. CONCLUSIONS: FRC significantly decreased from the awake state to surgery in both groups. FRC was not influenced by FIO2 elevation at anesthesia induction.

[Perioperative management of lung transplantations in patients with pulmonary arterial hypertension compared with that in patients with lymphangiomyomatosis].

BACKGROUND: The number of lung transplantation has tended to increase as a treatment for patients with pulmonary arterial hypertension (PAH) and lymphangiomyomatosis (LAM) in Japan. However, we have little evidence about the comparison of perioperative management in patients with PAH and that in patients with LAM. METHODS: In this retrospective study, ten patients with PAH and seventeen patients with LAM who underwent the lung transplantations between 2006 and 2011 were enrolled. RESULTS: PAH patients received double lung transplantation with intraoperative cardiopulmonary bypass (CPB) support. Before anesthesia induction, percutaneous cardiopulmonary support (PCPS) was begun. Most of LAM patients received single lung transplantation without using CPB support and PCPS support before anesthesia induction. But sometimes during an operation PCPS support was necessary. Postoperative PCPS support showed no significant differences between PAH and LAM. The four year survival rate was 80% (PAH) and 87.8% (LAM). Pao2/FIo2 in patients with PAH and in those with LAM, %FEV10 in those with LAM after surgery improved when compared to those before surgery. CONCLUSIONS: The large difference in perioperative management between patients with PAH and those with LAM is an important knowledge for anesthesist.

[Assessment of the perioperative factors contributing to the hemodynamic changes during surgery in ten patients with pheochromocytoma].

BACKGROUND: Intensive perioperative management is required for adrenalectomy in patients with pheocromocytoma because of the unstable hemodynamics and life threatening cardiovascular disturbances due to catecholamine surge from the neuroendocrine tumors. The aim of this study was to assess the perioperative factors contributing to the hemodynamic changes during surgery in pheochromocytoma. METHODS: Ten patients with pheochromocytoma undergoing elective adrenalectomy were enrolled in this retrospective study. The circulating blood volume before surgery and the perioperative factors associated with hemodynamic changes during surgery were assessd by the pulse dye densitometry and VigileoTM/ FroTracTM system, respectively. RESULTS: The decreases of blood pressure after resections of the central veins from tumors were significantly greater in laparotomy than those in laparoscopic surgery (P<0.05). In addition, the decreases of blood pressure after resection of the central were correlated with tumor sizes (R= -0.611), perioperative noradrenaline (NA) blood levels (R= -0.860), perioperative amounts of NA in urine (R= -0.743), and mean stroke volume variations for 5 min after resection of the veins(R= - 0.679). CONCLUSIONS: The decreases of blood pressure after resections of the central veins are dependent on the perioperative blood NA levels, the level of NA in the perioperative urine testig, and tumor sizes.

Targeted amplicon sequencing of wastewater samples for detecting SARS-CoV-2 variants with high sensitivity and resolution.

Wastewater-based epidemiology (WBE) is a promising approach for monitoring the spread of SARS-CoV-2 within communities. Although qPCR-based WBE is powerful in that it allows quick and highly sensitive detection of this virus, it can provide limited information about which variants are responsible for the overall increase or decrease of this virus in sewage, and this hinders accurate risk assessments. To resolve this problem, we developed a next generation sequencing (NGS)-based method to determine the identity and composition of individual SARS-CoV-2 variants in wastewater samples. Combination and optimization of targeted amplicon-sequencing and nested PCR allowed detection of each variant with sensitivity comparable to that of qPCR. In addition, by targeting the receptor binding domain (RBD) of the S protein, which has mutations informative for variant classification, we could discriminate most variants of concern (VOC) and even sublineages of Omicron (BA.1, BA.2, BA.4/5, BA.2.75, BQ.1.1 and XBB.1). Focusing on a limited domain has a benefit of decreasing the sequencing reads. We applied this method to wastewater samples collected from a wastewater treatment plant in Kyoto city throughout 13 months (from January 2021 to February 2022) and successfully identified lineages of wild-type, alpha, delta, omicron BA.1 and BA.2 as well as their compositions in the samples. The transition of these variants was in good agreement with the epidemic situation reported in Kyoto city during that period based on clinical testing. These data indicate that our NGS-based method is useful for detecting and tracking emerging variants of SARS-CoV-2 in sewage samples. Coupled with the advantages of WBE, this method has the potential to serve as an efficient and low cost means for the community risk assessment of SARS-CoV-2 infection.

Increased circulating endothelial microparticles in COPD patients: a potential biomarker for COPD exacerbation susceptibility.

RATIONALE: The influence of COPD exacerbation on the endothelium is not completely understood. Circulating endothelial microparticles (EMPs) are membrane vesicles in circulating blood that are shed by activated or apoptotic endothelial cells. OBJECTIVE: To compare EMP numbers in stable COPD patients with those during and after exacerbation. METHODS: We examined the EMP numbers in 80 stable COPD patients, 27 patients with exacerbated COPD, and 20 healthy non-COPD volunteers. EMPs were defined as CD144+ MPs (VE-cadherin EMPs), CD31+/CD41- MPs (PECAM EMPs), CD146 MPs (MCAM EMPs) and CD62E+ EMPs (E-selectin EMPs) as analysed by FACS. Von Willebrand factor (vWF) expression was utilised to identify the origins of the EMPs. RESULTS: VE-cadherin, PECAM and E-selectin EMP numbers were significantly higher in the stable COPD patients than in the non-COPD volunteers, and they were significantly higher in the patients with exacerbated COPD than in the stable COPD patients. The majority of these increased EMPs were vWF-negative, indicating a pulmonary capillary origin. Baseline E-selectin EMP levels were significantly higher in COPD patients who experienced frequent exacerbations than in those who did not have frequent exacerbations (p<0.001). Twenty-eight days after the onset of exacerbation, E-selectin EMP levels returned to those observed in stable COPD patients, whereas PECAM EMP levels remained high. MCAM EMP numbers were not elevated in stable or exacerbated-COPD patients. CONCLUSIONS: Endothelial damage, mainly in pulmonary capillaries, occurs during exacerbation and continues even after clinical symptoms disappear. Higher baseline E-selectin EMP levels may indicate COPD patients who are susceptible to exacerbation.

Remifentanil use for cesarean section in a patient with intracranial re-ruptured arteriovenous malformation.

We describe the successful administration of remifentanil as part of the anesthetic technique used for cesarean section performed under general anesthesia in a 24-year-old woman with intracranial re-hemorrhage caused by re-ruptured arteriovenous malformation. A low dose of remifentanil was useful to obtund the hypertensive response during induction and maintenance of anesthesia without neonatal respiratory depression.

A case of congenital central hypoventilation syndrome.

We encountered a 2-year-old female infant with congenital central hypoventilation syndrome (CCHS) who underwent an abdominal operation for strangulated ileus. Prior to the surgery, at home, the infant had been receiving non-invasive positive-pressure ventilation (NPPV) support only during sleep. However, after postoperative extubation, the blood oxygen saturation (SpO(2)) decreased to approximately 90 % with NPPV during sleep alone, necessitating the use of biphasic cuirass ventilation (BCV) along with NPPV for 2 days. The infant was weaned from the BCV on hospital day 9, and was discharged from the intensive care unit (ICU) on hospital day 13. Although it has been said that CCHS is not under the control of the respiratory center, there are no reports of the true CO(2) response curves in these patients. Therefore, during respiratory management in the ICU post-surgery, we examined (with the consent of the mother) the relationship of the end-tidal carbon dioxide (ETCO(2)) to the tidal volume and respiratory rate, for a period of 6 min in the absence of sedation, using a respiratory profile monitor. Electrocardiographic and SpO(2) monitoring was also conducted at the same time, to ensure the patient's safety. In this patient, while the ETCO(2) increased, the tidal volume and respiratory rate remained unchanged. No relationship was found between the tidal volume and the respiratory rate. Various modalities have been used for the treatment of CCHS (tracheotomy, NPPV, and diaphragmatic pacing). Treatment of these patients in the ICU should be tailored to the needs of individual patients and their families.

Impact of changes of positive end-expiratory pressure on functional residual capacity at low tidal volume ventilation during general anesthesia.

PURPOSE: Several reports in the literature have described the effects of positive end-expiratory pressure (PEEP) level upon functional residual capacity (FRC) in ventilated patients during general anesthesia. This study compares FRC in mechanically low tidal volume ventilation with different PEEP levels during upper abdominal surgery. METHODS: Before induction of anesthesia (awake) for nine patients with upper abdominal surgery, a tight-seal facemask was applied with 2 cmH(2)O pressure support ventilation and 100 % O(2) during FRC measurements conducted on patients in a supine position. After tracheal intubation, lungs were ventilated with bilevel airway pressure with a volume guarantee (7 ml/kg predicted body weight) and with an inspired oxygen fraction (FIO(2)) of 0.4. PEEP levels of 0, 5, and 10 cmH(2)O were used. Each level of 5 and 10 cmH(2)O PEEP was maintained for 2 h. FRC was measured at each PEEP level. RESULTS: FRC awake was significantly higher than that at PEEP 0 cmH(2)O (P < 0.01). FRC at PEEP 0 cmH(2)O was significantly lower than that at 10 cmH(2)O (P < 0.01). PaO(2)/FIO(2) awake was significantly higher than that for PEEP 0 cmH(2)O (P < 0.01). PaO(2)/FIO(2) at PEEP 0 cmH(2)O was significantly lower than that for PEEP 5 cmH(2)O or PEEP 10 cmH(2)O (P < 0.01). Furthermore, PEEP 0 cmH(2)O, PEEP 5 cmH(2)O after 2 h, and PEEP 10 cmH(2)O after 2 h were correlated with FRC (R = 0.671, P < 0.01) and PaO(2)/FIO(2) (R = 0.642, P < 0.01). CONCLUSIONS: Results suggest that PEEP at 10 cmH(2)O is necessary to maintain lung function if low tidal volume ventilation is used during upper abdominal surgery.