[Techniques for quantifying endotypes of obstructive sleep apnea].

Obstructive sleep apnea (OSA) is the frequent occurrence of apnea and/or hypopnea during sleep, leading to intermittent hypoxia, hypercapnia, and disruption of sleep architecture, further resulting in multisystem damage. The pathophysiological mechanisms include abnormal anatomical structure, low arousal threshold, high loop gain, and poor muscle reactivity, etc. As there are individual differences in the underlying mechanisms of OSA (i.e. endotypes), the effectiveness of treatment and prognosis may also vary according to these characteristics. Understanding the endotype of OSA is critical to understanding which patients are most likely to benefit from non-invasive ventilation therapy. Quantification of endotypes is central to the precision treatment of OSA and may provide the basis for accurate clinical treatment of OSA based on endotypes.

[Prediction models for respiratory event types in OSA patients based on hypoxic parameters].

Objective: To analyze the hypoxic parameters in patients with obstructive sleep apnea (OSA), to explore the difference and association between different types of respiratory events and to construct predictive models for respiratory event types. Methods: Fifty patients [including 41 males and 9 females with age 18-74(45.72±13.39) years ] with OSA diagnosed by polysomnography (PSG) were selected for retrospective analysis, and all respiratory events with pulse oximetry (SpO2) desaturation in the recorded overnight data were divided into hypopnea group (Hyp, 3 316), obstructive apnea group (OA, 5 552), central apnea group (CA, 1 088) and mixed apnea group (MA, 1 369) according to the type of events, and all event records were exported separately from the PSG software as comma-separated variable (.csv) files, which were imported and analyzed using the in-house built Matlab software. A total of 13 hypoxic parameter differences were compared among the four groups, including minimum oxygen saturation of events (e-minSpO2), the depth of desaturation (ΔSpO2), the duration of desaturation and resaturation (DSpO2), the duration of desaturation (d.DSpO2), duration of resaturation (r.DSpO2), duration of SpO2<90% (T90), duration of SpO2<90% during desaturation (d.T90), duration of SpO2<90% during resaturation (r.T90), area under the curve of SpO2<90% (ST90), area under the curve of SpO2<90% during desaturation (d.ST90), area under the curve of SpO2<90% during resaturation (r.ST90), oxygen desaturation rate (ODR) and oxygen resaturation rate (ORR). Hyp model (H), OA model (O), CA model (C) and MA model (M) were constructed respectively; group differences for the different hypoxia parameters were assessed using single factor analysis and Kruskal-Wallis H test. For different categories of respiratory events, binary logistic regression was used to identify the variables included in the regression model. Receiver operating characteristic (ROC) curves were generated to assess and compare the sensitivity, specificity, positive predictive value and negative predictive value of the four models, thereby gauging the predictive precision of each model. Results: ΔSpO2, ODR, ORR, T90, d.T90, r.T90, ST90, d.ST90 and r.ST90 for each type of respiratory events showed MA>OA>CA>Hyp, and e-minSpO2 showed MA

Evolving information complexity of coarsening materials microstructures.

The temporal evolution of microstructural features in metals and ceramics has been the subject of intense investigation over many years because deviations from normal grain growth behavior are ubiquitous and strongly dictate observed mechanical and magnetic properties. To distinguish among different grain growth scenarios, we examine the time evolution of the information content of both synthetic and experimental coarsening microstructures as quantified by both a computable information density (CID) and a spectral entropy along with selected metrics and measures of shared information and interaction strength. In these approaches, microstructural evolution is described in terms of two time series representations, namely: (1) strings and their compressed counterparts that reflect the information contained in the configuration of a system over time, and (2) the spectra of graph Laplacians that embody the information contained in a coarsening grain network. These approaches permit one to characterize dynamically evolving microstructures and to identify correlation times associated with different coarsening scenarios. Moreover, as the information content of a system is a proxy for the entropy, a thermodynamic description of grain growth is also described.

[Relationship between respiratory event-related arousal and increased pulse rate in patients with obstructive sleep apnea].

Objective: To investigate the relationship between respiratory event-related arousal and increased pulse rate in patients with obstructive sleep apnea (OSA), and to evaluate whether elevated pulse rate can be used as a surrogate marker of arousal. Methods: A total of 80 patients [40 males and 40 females, age range (18-63 years), mean age (37±13) years] who attended the Sleep Center of the Department of Respiratory and Critical Care Medicine, Tianjin Medical University General Hospital for polysomnography (PSG) from January 2021 to August 2022 were enrolled. Stable PSG recordings of non-rapid eye movement (NREM) sleep to compare the mean pulse rate (PR), the lowest PR 10 seconds before the onset of arousal, and the highest PR within 10 seconds after the end of arousal associated with each respiratory event. At the same time, the correlation between the arousal index and the pulse rate increase index (PRRI), as well as ΔPR1 (highest PR-lowest PR) and ΔPR2 (highest PR-mean PR), respectively, with the duration of respiratory events, the duration of arousal, the magnitude of pulse oximetry (SpO2) decline, and the lowest SpO2 was analyzed. Among the 53 patients, 10 events without arousal and 10 events with arousal (matched for the magnitude of SpO2 decline) were selected for NREM in each of the 53 patients, and ΔPR before and after termination of respiratory events in the two groups was compared. In addition, 50 patients were simultaneously subjected to portable sleep monitoring (PM) and divided into non-severe OSA group (n=22) and severe OSA group (n=28), and ΔPR≥3 times,≥6 times,≥9 times, and≥12 times after respiratory events were used as surrogate markers of arousal, and ΔPR was scored manually and integrated into the respiratory event index (REI) of PM. Then, we compared the agreement between REI calculated from the four PR cut-off points and the apnea-hypopnea index (AHIPSG) calculated by the gold standard PSG. Results: ΔPR1 [(13±7)times/min] and ΔPR2 [(11±6)times/min] were significantly higher in patients with severe OSA than in patients with non-OSA,mild and moderate OSA. The arousal index was positively correlated with the four PRRIs (r 0.968, 0.886, 0.773, 0.687, P<0.001, respectively), and the highest PR [(77±12) times/min] within 10 s after the end of arousal was significantly higher than the lowest PR [(65±10) times/min, t=113.24, P<0.001] and the mean PR [(67±11) times/min, t=103.02, P<0.001]. ΔPR1 and ΔPR2 were moderately correlated with the decrease in SpO2 (r=0.490, 0.469, P<0.001). After matching the magnitude of SpO2 decline, the ΔPR[(9±6)/min] before and after the termination of respiratory events with arousal was significantly higher than that of respiratory events without arousal [(6±5)/min, t=7.72, P<0.001]. The differences between REI+PRRI3 and REI+PRRI6 and AHIPSG in the non-severe OSA group were not statistically significant (P values 0.055 and 0.442, respectively), and REI+PRRI6 and AHIPSG showed good agreement (the mean difference was 0.7 times/h, 95%CI 8.3-7.0 times/h). The four indicators of PM in the severe OSA group were statistically different from AHIPSG (all P<0.05), and the agreement was poor. Conclusions: Respiratory event-related arousal in OSA patients is independently associated with increased PR, and frequent arousal may lead to increased frequency of PR fluctuations, and elevated PR may be used as a surrogate marker of arousal, especially in patients with non-severe OSA, where elevated PR≥6 times significantly improves the diagnostic agreement between PM and PSG.

Oral Pathobionts Promote MS-like Symptoms in Mice.

Dysbiotic oral microbiota has been associated with multiple sclerosis. However, the role and mechanism of oral microbiota in the development of multiple sclerosis are still elusive. Here, we demonstrated that ligature-induced periodontitis (LIP) aggravated experimental autoimmune encephalomyelitis (EAE) in mice, and this was likely dependent on the expansion of T helper 17 (Th17) cells. LIP increased the splenic richness of Enterobacter sp., which was able to induce the expansion of splenic Th17 cells and aggravate EAE in mice. LIP also led to enrichment of Erysipelotrichaceae sp. in the gut and increased Th17 cells in the large intestinal lamina propria of EAE mice. Fecal microbiota transplantation from EAE mice with LIP also promoted EAE symptoms. In conclusion, periodontitis exacerbates EAE, likely through ectopic colonization of oral pathobionts and expansion of Th17 cells.

[Clinical features and outcomes of newly diagnosed follicular lymphoma concurrent with diffuse large B-cell lymphoma component].

Objective: To explore the clinical features and survival of newly diagnosed follicular lymphoma (FL) patients with diffuse large B-cell lymphoma (DLBCL) component. Methods: 1845 newly diagnosed FL patients aged ≥ 18 years with grades 1-3a in 11 medical centers in China from 2000 to 2020 were included, and patients with DLBCL component were screened. The clinical data and survival data of the patients were retrospectively analyzed, and the prognostic factors were screened by univariate and multivariate analysis. Results: 146 patients (7.9% ) with newly diagnosed FL had DLBCL component. The median age was 56 (25-83) years, 79 males (54.1% ) . The pathology of 127 patients showed the proportion of DLBCL component. Patients were divided into two groups according to whether the proportion of DLBCL component was ≥ 50% . The study found that patients with DLBCL component ≥ 50% had higher grade 3 ratio (94.3% vs 91.9% , P=0.010) , Ki-67 index ≥ 70% ratio (58.5% vs 32.9% , P=0.013) and PET-CT SUVmax ≥ 13 ratio (72.4% vs 46.3% , P=0.030) than patients with DLBCL component<50% . All patients received CHOP or CHOP like ± rituximab chemotherapy. The overall response rate (ORR) was 88.2% , and the complete response (CR) rate was 76.4% . In the groups with different proportions of DLBCL component, there was no significant difference in the remission rate after induction treatment and the incidence of disease progression within 2 years after initiation of treatment (POD24) (P<0.05) . The overall estimated 5-year progression free survival (PFS) rate was 58.9% , and the 5-year overall survival (OS) rate was 90.4% . The 5-year OS rate of POD24 patients was lower than that of non POD24 patients (70.3% vs 98.5% , P<0.001) . Compared with non maintenance treatment of rituximab, maintenance treatment of rituximab could not benefit the 5-year PFS rate (57.7% vs 58.8% , P=0.543) , and the 5-year OS rate had a benefit trend, but the difference was not statistically significant (100% vs 87.8% , P=0.082) . Multivariate analysis showed that failure to reach CR after induction treatment was an independent risk factor for PFS (P=0.006) , while LDH higher than normal was an independent risk factor for OS (P=0.031) . Conclusion: FL patients with DLBCL component ≥50% have more invasive clinical and pathological features. CHOP/CHOP like ± rituximab regimen can improve the clinical efficacy of patients. Rituximab maintenance therapy can not benefit the PFS and OS of patients. Failure to reach CR after induction therapy was the independent unfavorable factor for PFS.

[Research progress of acetaldehyde dehydrogenase 2 in liver diseases].

Acetaldehyde dehydrogenase 2 (ALDH2) is an important kind of aldehyde dehydrogenase in mitochondria, which has the function of eliminating acetaldehyde and other toxic aldehydes substances. Furthermore, it is abundant in liver and is closely related to the occurrence and development of a variety of liver diseases. ALDH2 genetic polymorphisms plays an important role in the occurrence of a variety of liver diseases in the human population.This paper mainly reviews the research progress of ALDH2 in liver diseases in recent years, with a view to provide theoretical basis for clinical prevention and treatment.

[Effect of peritoneum reconstruction on postoperative complications after laparoscopic low anterior resection for rectal cancer].

Objective: To determine the effect of peritoneum reconstruction on postoperative complications after laparoscopic low anterior resection (LAR) for rectal cancer. Methods: Retrospective cohort study and propensity score matching were conducted. Case inclusion criteria: (1) pathologically confirmed rectal adenocarcinoma; (2) 18 to 80 years; (3) patients with middle to low rectal cancer undergoing laparoscopic LAR; (4) patients staging cT1-4aN0-2M0 or ycT1-4aN0-2M0 after neoadjuvant therapy; (5) the distance of 4-10 cm from tumor low margin to anal verge. Exclusion criteria: (1) abdominal surgery history (except appendicitis, cholecystitis, ectopic pregnancy); (2) anastomosis above the peritoneal reflection; (3) tumor distant metastasis or clinical staging of T4b during surgery; (4) conversion to open surgery; (5) severe incapacitating disease (American Society of Anesthesiologists classification IV or V, ASA). A total of 666 patients with middle to low rectal cancer undergoing laparoscopic LAR in The First Affiliated Hospital of Army Medical University from January 2017 to June 2020 were enrolled. There were 473 males and 193 females with the median age of 59 (18-80) years. Laparoscopic LAR with peritoneum reconstruction was performed in 188 cases (PR group), and laparoscopic LAR without peritoneum reconstruction was performed in 478 cases (NPR group). After 1:1 propensity score matching according to 1:1 based on age, gender, body mass index, TNM staging, ASA classification, intraoperative blood loss, distance from tumor low margin to anal edge, 153 cases were included in each group. Postoperative complications were classified according to Clavien-Dindo classification. Anastomotic leakage was defined and graded according to the International Study Group of Rectal Cancer (ISGRC) criteria. Results: After propensity score matching, there were no significant differences in baseline demographic characteristics between the 2 groups (all P>0.05), indicating that these two groups were comparable. (1) Operative conditions: All the patients in both groups completed operation successfully. Compared with the NPR group, the PR group had longer operation time [(181.3±60.3) minutes vs. (168.9±51.5) minutes, t=2.185, P=0.029], shorter postoperative median hospital stay [8 (7, 10) days vs. 9 (7, 11) days, Z=-2.282, P=0.022], and the differences were statistically significant (P<0.05). (2) Postoperative complications: The overall morbidity of postoperative complication in PR group and NPR group was 20.3% (31/153) and 24.2% (37/153) respectively, and the incidence of anastomotic leakage was 9.8% (15/153) and 11.1%(17/153) respectively, whose differences were not statistically significant (both P>0.05). Compared with NPR group, PR group had lower morbidity of grade III to IV complications [3.9% (6/153) vs. 11.1% (17/153), χ(2)=5.688, P=0.017] and lower secondary operation rate [1.3% (2/153) vs. 5.9% (9/153), χ(2)=4.621, P=0.032], the differences were statistically significant (both P<0.05). Though PR group had lower incidence of grade C anastomoic leakage [1.3% (2/153) vs. 3.9% (6/153), χ(2)=2.054, P=0.152], but the differences were not statistically significant. (3) Postoperative inflammation: The difference of the procalcitonin level of both PR and NPR groups at postoperative 1-d, 3-d, and 5-d was statistically significant (F=5.222, P=0.010) in time-dependent manner, while the difference was not significant in the interaction effect (P>0.05). No statistically significant differences in the C-reactive protein level between two groups at postoperative 1-d, 3-d, and 5-d were found (all P>0.05). Conclusion: Peritoneum reconstruction in laparoscopic LAR can decrease the morbidity of postoperative complication of grade III to IV and the reoperation rate, and plays an important role in controlling the inflammatory reaction, which has great clinical value.

[CRISPR/Cas9-mediated microRNA-21 knockout increased imatinib sensitivity in chronic myeloid leukemia cells].

Objective: To observe the effects of miR-21 knockout on proliferation and drug resistance in K562/G01 cells, and to preliminarily explore the mechanism of imatinib sensitivity by knocking out miR-21 in K562/G01 cells. Methods: Using CRISPR/Cas9 to knock out the miR-21 gene in K562/G01 cells, and single-cell-derived clones of miR-21 knockout were obtained by genomic DNA PCR screening, Sanger sequencing, and real-time PCR. We used MTT and cell colony formation assays to assess the cell proliferation, and determined imatinib sensitivity by MTT assay and Annexin-Ⅴ-APC/7-AAD double staining flow cytometry. Using western blot, we examined the potential mechanisms affecting imatinib sensitivity by knocking out miR-21 in K562/G01 cells. Results: Three miR-21 knockout K562/G01 single-cell-derived clones were successfully constructed. The mutation efficiency mediated by CRISPR/Cas9 was 7.12%-8.11%. MiR-21 knockout inhibited the proliferation of K562/G01 cells; the clone formation rates of WT and 1#, 2#, 6# K562/G01 single-cell clones were (57.67±8.25) %, (26.94± 5.36) %, (7.17±2.11) %, (31.50±3.65) %, respectively. MiR-21 knockout increased the sensitivity of K562/G01 cells to imatinib, IC(50) of imatinib in WT, and 1#, 2#, 6# K562/G01 single-cell clones were (21.92±1.36) µmol/ml, (3.98±0.39) µmol/ml, (5.38±1.01) µmol/ml, (9.24±1.36) µmol/ml. After the knockout of miR-21, the activation of PI3K/Akt signaling molecules was inhibited, while the expression of P210(B)CR-ABL and p-P210(BCR-ABL) was downregulated; however, the expression of PTEN was not affected. Conclusion: The knockout of miR-21 can suppress cell proliferation and improve sensitivity to imatinib in K562/G01 cells, which may be achieved by inhibiting the PI3K/AKT signaling pathway and BCR-ABL expression.

[Value of night pulse oximetry monitoring in obstructive sleep apnea hypopnea syndrome prediction and classification].

Objective: To explore the value of night pulse oximetry monitoring in the prediction and classification of obstructive sleep apnea hypopnea syndrome (OSAHS). Methods: From January 2018 to December 2019, 580 snoring patients admitted to the Sleep Center of Tianjin Medical University General Hospital were analyzed retrospectively. There were 418 males and 162 females, aging 13-85(49±14) years. All subjects underwent polysomnography, and the apnea hypopnea index (AHI)was 0-101.4(43.06±27.47) times/hour. There were 52 cases in the non-OSAHS group (AHI<5 times/h), 69 cases in the mild OSAHS group (5 times/h30 times/h) was 94.74%±0.76%. Conclusion: Based on the signals recorded by the SpO2 monitor, the methods of using MLR model for AHI prediction and using BPNN model for multi-classification may have higher value for the prediction and classification of OSAHS.

Multiple b-value diffusion-weighted imaging in differentiating benign from malignant breast lesions: comparison of conventional mono-, bi- and stretched exponential models.

AIM: To prospectively evaluate multiple b-value diffusion-weighted imaging (DWI) in differentiating malignant from benign breast lesions. MATERIALS AND METHODS: The study cohort included 103 patients who underwent 3 T magnetic resonance imaging (MRI). The conventional sequences included T1-weighted dynamic contrast-enhanced, T1-weighted and T2-weighted fat-suppressed sequences, single b-value (b=0, 1000 s/mm2) DWI, and multiple b-values (12 values, from 0 to 3,000 s/mm2) DWI. Pathological diagnosis of breast lesions was based on the latest World Health Organization (WHO) guide on the pathology and immunohistochemistry of the breast. SPSS Statistics V19.0 was used for the statistics analysis. RESULTS: The following parameters were calculated: apparent diffusion coefficient (ADC), tissue diffusivity (D), perfusion fraction (f), pseudo-diffusion coefficient (D∗), distributed diffusion coefficient (DDC), and alpha (α) by the same radiologist twice (interval time of 3 months). There was good inter/intra-observer agreement for each of the parameters. The D, D∗, f, DDC, and α values were significantly different among malignant tumours, benign lesions, and normal breast tissue (p<0.05). CONCLUSION: D, f, DDC, α, and ADC values have good sensitivity and specificity, respectively. In addition, the combined use of D and f or DDC and α has good diagnostic performance. Thus, the applications of the new multi-b DWI variables or combined variables are promising.

[Clinical characteristics in patients with hypervirulent Klebsiella pneumoniae infection and its capsular serotypes and multilocus sequence typing].

Objective: To describe the clinical characteristics of hypervirulent Klebsiella pneumoniae (hvKP) infection. To analyze the antibiotic susceptibility of hvKP to provide the empiric antibiotic options. To investigate capsule serotype and sequence type (ST) of hvKP and their correlation with clinical profiles. Methods: hvKP was defined as bacteria isolated from patients with community-acquired pyogenic liver abscess (CA-PLA) with co-infection sites outside liver or a bloodstream infection in a host without underlying biliary tract diseases. Patients with CA-PLA hospitalized in the First Hospital of China Medical University were retrospectively analyzed from January 2011 to December 2017. Antibiotic susceptibility was detected by automatic bacterial identification and antibiotic susceptibility analysis system in vitro. Polymerase chain reaction method and gene sequencing were used to detect the main capsule serotype and ST. Results: A total of 140 cases with hvKP infection were enrolled. The co-infections outside liver abscess included 98 bloodstream infections, 53 pneumonia, 11 perianal abscess, 10 urinary system infections, 3 subphrenic abscess, 3 endophthalmitis, 2 spleen abscess, and other miscellaneous infections including 1 peritonitis, 1 skin and soft tissue infection, 1 myelitis, 1 colitis, 1 psoas major abscess and 1 myocardial abscess. Among the 140 cases, 106 presented with single co-infection site, 32 with 2 sites, and 2 with 3 sites. HvKP manifested high antibiotic susceptibility up to 80% for most commonly used antibiotics. Capsule serotyping of 43 revived isolates indicated that K1 serotype accounted for 53.49% (23/43), K2 34.88 (15/43), K54 2.33% (1/43), K57 2.33% (1/43), and other serotypes 6.98%(3/43). There was no significant distribution among K1, K2, K54 and K57 of hvKP capsule serotypes in patients with or without diabetes mellitus (P>0.05). Multilocus sequence typing (MLST) suggested that ST23 and ST65 were predominant accounting for 39.53% (17/43) and 25.58% (11/43) respectively. No serotype or ST predominance was seen in any of the clinical infections. Conclusion: HvKP is related to a wide spectrum of infectious diseases, including multiple extrahepatic sites and bloodstream infections besides CA-PLA with high antibiotic susceptibility. K1 and K2 are the predominant capsule serotypes, and ST 23 and ST65 are the predominant sequence types.

[Autologous peripheral blood stem cell transplantation for POEMS syndrome].

Six patients with POEMS syndrome who received autologous peripheral blood stem cell transplantation (auto-PBSCT) were retrospectively analyzed. Conditioning regimen was high dose melphalan. Peripheral blood stem cells were collected after mobilization with cyclophosphamide (CTX) and growth factors. One patient presenting hydrothorax and ascites was treated with 3 cycles of lenalidomide and dexamethasone before mobilization. Auto-PBSCT was fairly tolerable. Hematopoietic reconstitution was successful in all patients without transplantation-related mortality. A decrease or normalization of serum vascular epithelial growth factor (VEGF) was observed in all patients at 3 months after transplantation. The neurological remission was seen in 5/6 patients.

[Study on the characteristics of major birth defects in 1.69 million cases of fetus in Guangxi Zhuang Autonomous Region].

Objective: Tracking the information on 1.69 million fetal cases across Guangxi Zhuang Autonomous Region (Guangxi) so as to study the occurrences of total and major birth defects in order to evaluate the ability on related prevention and control programs in Guangxi. Methods: Using the self-developed "Gui Women's System" to establish a database of 1.69 million fetal cases in Guangxi and to analyze the distribution of time, space and population, as well as the outcomes of pregnancy, using the big data. Results: During the 29 months of observation, the overall live birth rate was 99.25%, with stillbirth rate during pregnancy as 0.44%, stillbirth rate during birth as 0.02%, and the 0-6 days mortality rate as 0.14%. The total detection rate on birth defects was 197.63/10 000; the incidence rate was 103.04/10 000, the birth rate was 102.55/10 000. The overall discovery rate of major birth defects was 48.33/10 000, with the incidence rate as 783 000, the birth rate as 0.58/10 000. The discovery rates of major birth defects in 14 cities were between 35 and 68/10 000, and the birth rate dropped significantly to less than 1.00 in 10 000. Nationalities showed that the number of pregnant women with birth defects more than 50 000 would include Hui (9.68/10 000), Yao (9.57/10 000), and Jing (9.37/10 000). With the increasing age of gestation, number of birth defects, incidence of major birth defects also increased. Ninety-five percent of the major birth defects were found within <28 weeks and with the top 5 kinds of major birth defects as complicated congenital heart disease (9.11/10 000), alpha thalassemia (8.36/10 000), and 21-trisomy syndrome (7.85/10 000), beta thalassemia (5.32/10 000) and fetal edema syndrome (4.92/10 000). The top 5 major birth defects appeared as complicated congenital heart disease (9.11/10 000), alpha thalassemia (8.36/10 000), and 21-trisomy syndrome (7.85/10 000), beta thalassemia (5.32/10 000) and fetal edema syndrome (4.92/10 000). Conclusion: Programs leading to increase the rate on discovery of major birth defects were fundamental in effectively reducing the major birth defects.

VE/VCO2 Slope and Functional Capacity in Patients Post-Heart Transplantation.

BACKGROUND: The ventilatory efficiency represented cardiovascular, pulmonary, and musculoskeletal performance into an integrate index has been used as long-term and short-term prognostic variables in congestive heart failure. The heart failure patients post heart transplantation, whether the ventilatory efficiency was also normalized is still unknown. METHODS: This was a cross-sectional study. We measured ventilation to carbon dioxide production slope and oxygen consumption in peak exercise (peak VO2) by cardiopulmonary exercise test, which represented ventilatory efficiency and functional capacity respectively. Strength of hand grip, the 30-second chair stand test, and 6-minute walking test were also evaluated. Patients with ventilation to carbon dioxide production slope <30 were defined as the normal group; others were defined as the abnormal group. Independent t tests and paired t tests were used when appropriate. The level of statistical significance was set at .05. RESULTS: There were 51 clinically stable post-heart transplantation patients (age 53 ± 12.4 years; 86.3% were male) at 65.14 ± 41.17 months after transplantation. The ventilation to carbon dioxide production slope was 29.2 ± 5.6, which significantly improved compared to that recorded 1 month after heart transplantation (32.6 ± 6.4). There were 20 patients in the abnormal group, characterized by lower 6-minute walking test distance (normal vs abnormal, 422.5 ± 97.8 vs 532.6 ± 87.6 m) and peak VO2 (normal vs abnormal, 14.9 ± 5.3 vs 18.8 ± 5.1 mL/kg/min). The abnormal ventilation to carbon dioxide production slope was significantly correlated with 6-minute walking test distances in multivariate analyses. CONCLUSION: Our findings indicate that the ventilation to carbon dioxide production slope is partially abnormal among patients post-heart transplantation. A ventilation to carbon dioxide production slope above the normal range is characterized by a lower peak VO2 during cardiopulmonary exercise test and lower 6-minute walking test distance. The ventilation to carbon dioxide production slope is also significantly negatively correlated with peak VO2, peak work rate, and 6-minute walking test distance. The prognostic utility of the ventilation to carbon dioxide production slope for patients post-heart transplantation requires further investigation.