Experience with Tension‐free Vaginal Tape (TVT)‐SECUR for Female Stress Urinary Incontinence

Objectives: Tension‐free vaginal tape (TVT)‐SECUR is a technique specifically designed to place a short suburethral mesh sling for the treatment of female stress urinary incontinence (SUI). The aim of the technique is to decrease surgical morbidity. We report our experience of applying this technique on 10 patients. Methods: From June 2007 to July 2007, 10 female patients with SUI underwent TVT‐SECUR placement operation. The sling was inserted in a suprapubic direction over the inner surface of pubic bone (U‐shaped technique). Nine of the patients underwent videourodynamic study (VUDS). The maximal bladder neck decent distance (MBND) by abdominal straining was determined. We identified intrinsic sphincter deficiency (ISD) as a valsalva leak point pressure lower than 60 cm H₂O and hypermobility as MBND more than 2 cm. Results: Two patients had pure ISD, three had hypermobility, and four had both ISD and hypermobility. All patients remained continent for first month after surgery. SUI recurred in five of nine patients at an average of 2.5 months. The recurrence appeared in all three groups of patients. The recurrent SUI was so severe that three patients required repeat surgery using percutaneous prolene tape sling. After surgery, no further SUI was noted in the three patients. During surgery the TVT‐SECUR sling was found to have firmly adhered to perivesical tissue rather than to the pubic bone. Conclusion: Our experience shows that the current design of the TVT‐SECUR results in unpredictable outcomes. Some placed slings may migrate away from the inner surface of the pubic bone. To act as a reliable “hammock”, the sling must be securely fixed on immobile structures independent from the bladder/urethra.     

Secondary Transobturator Tape Procedure after Combined Pelvic Organ Prolapse Repair

A 66‐year‐old female who underwent a partial urethrectomy complained of severe incontinence due to intrinsic sphincter deficiency. Bone anchor surgical technique was performed, but in 3 years, serious pelvic organ prolapse had occurred. Consequently, anterior and posterior tension‐free vaginal mesh operation was planned. Preoperative urodynamic examination predicted postoperative stress incontinence, and concurrent transobturator tape (TOT) surgery was performed. After 3 months, stress incontinence reoccurred, and secondary TOT was performed. Relapse was probably caused by dislocation of the first TOT towards the bladder neck. Thus, the secondary TOT was placed distal to the initial tape towards the external urethral meatus, and proper tension was applied. After the operation, stress incontinence was cured. Thus, a second TOT procedure, with proper positioning and tensioning, can effectively cure stress incontinence that occurs after an initial TOT procedure.     

无张力阴道尿道悬吊术治疗老年女性尿失禁六例临床分析

目的 探讨无张力阴道尿道中段悬吊术(TVT)治疗老年女性尿失禁的临床意义和疗效。方法 采用SPRAC吊带系统对6例单纯性压力性尿失禁老年女性进行TVT治疗，分析其疗效及并发症。结果 6例TVT手术均在硬膜外麻醉下完成，平均手术时间31．6min，术中平均出血36．2ml，5例手术后24h内自行排尿，1例合并肥胖和阴道前壁膨出患者留置尿管1周后自行排尿。术后随访10～28个月，5例尿失禁治愈，1例手术后3个月再次发生尿失禁，2例术后伴不同程度的尿频、尿急，1例自觉耻骨后轻度不适。结论 TVT易操作、创伤小、疗效好，对绝经后老年女性合并肥胖和阴道前壁膨出的压力性尿失禁患者治疗有明显疗效。     

Simultaneous Treatment of Female Urethral Diverticulum and Stress Urinary Incontinence with Urethral Diverticulectomy and Suburethral Synthetic Mesh Sling

Objectives: Pubovaginal fascial sling along with urethral diverticulectomy has been advised as the most appropriate anti‐incontinence procedure for female stress urinary incontinence (SUI) with concomitant urethral diverticula (UD). We believe that suburethral synthetic mesh tape sling can also be safely used in some patients with concomitant SUI and UD. Herein, we present our experience for simultaneous treatment of UD and SUI with urethral diverticulectomy and suburethral synthetic mesh tape sling. Methods: From 2003 to 2008, there are three patients with UD and SUI in our institution. They received transvaginal urethral diverticulectomy and suburethral synthetic mesh tape sling simultaneously. Videourodynamics was done before and three months after the surgery. Results: Preoperative pelvis magnetic resonance imaging and videourodynamic study showed UD over distal urethra and SUI in all three patients. Urinalysis disclosed mild pyuria in two of the patients, and they both received intravenous antibiotics treatment to eradicate the infection prior to the surgery. They all underwent urethral diverticulectomy with suburethral synthetic mesh tape sling. The postoperative videourodynamic study showed no recurrence of UD and SUI. With a mean follow up of 33.3 months, there was no infection or exposure of synthetic mesh tape. Conclusions: In patients with UD and SUI, suburethral sling using synthetic mesh can be as effective and safe as facial sling in selected patients.     

Tension-free vaginal tape for the treatment of stress urinary incontinence in geriatric patients

OBJECTIVE: To evaluate the safety and efficacy of tension-free vaginal tape (TVT) for the treatment of stress urinary incontinence (SUI) in geriatric patients. PATIENTS AND METHODS: Fifty-one women, aged 65-80 (mean 72.3) years, underwent a TVT procedure for genuine SUI from 2001 to 2004. A urodynamic test together with uroflowmetry were performed. The patients' SUI bother score was assessed using a visual analog scale (VAS). RESULTS: The mean operative time was 25 (range 14-29) min and mean hospitalization time was 1.2 (range 1-2) days. Bladder perforation occurred in 3 cases (5.8%) and was managed conservatively. Pre- and postoperative maximum flow rate were not significantly different (p > 0.05). The patients' SUI bother score estimated by the VAS was statistically significantly improved (p < 0.0001). After a mean follow-up of 35.6 (range 14-60) months, 49 patients (96%) had no SUI, while 2 patients (3.9%) had persistent SUI. Also, during the follow-up 5 patients (9.8%) were diagnosed with de novo urgency due to detrusor overactivity and 1 patient (1.9%) had persistent dysuria that was resolved with urethrolysis. CONCLUSIONS: SUI in elderly women can be safely treated with the TVT procedure in the vast majority of the patients. However, bladder perforation during surgery and de novo urgency postoperatively should be taken into account.     

Different sling procedures for stress urinary incontinence: A lesson from 453 patients

Several midurethral sling (MUS) procedures, such as tension-free vaginal tape (TVT), TVT obturator (TVT-O), tension-free vaginal tape SECUR (TVT-S), and pubovaginal sling (PVS), have been used for the treatment of female stress urinary incontinence (SUI); however, which method is best for a particular patient group is not known. This study aimed to identify the best rationale for choosing the optimal MUS procedure for each patient. In total, 453 consecutive female patients with SUI who were treated with MUSs in West China Hospital of Sichuan University from September 2003 to September 2011 were enrolled in this study. All the patients underwent comprehensive pre-, intra-, and postoperative evaluations, including collection of demographic information, pelvic examination, and urodynamic testing, and operation-related complications were recorded. The Incontinence Quality of Life questionnaire was also completed. Under local or general anesthesia, 105 cases were treated with TVT, 243 with TVT-O, 90 with TVT-S, and 15 with PVS. Patients with different profiles in terms of age, symptom duration, concomitant procedures, urodynamic parameters, and pelvic organ prolapse (POP) quantification score were treated successfully; the body mass index did not differ significantly among the various treatment options. The cure and improvement rates were similar among the treatment groups: 97.14% (102/105) in TVT, 100% (243/243) in TVT-O, 98.89% (89/90) in TVT-S, and 100% (15/15) in PVS. Only minor complications were experienced by the patients. In conclusion, each MUS procedure was observed to be safe and effective in different subpopulations of patients, and the results suggest that appropriate patient selection is crucial for the success of each MUS procedure.     

The free portal pressure in awake patients with and without cirrhosis of the liver

ABSTRACT— The free portal pressure was measured by percutaneous transhepatic catheterization of the portal vein in 106 patients with cirrhosis of the liver and in 19 patients without liver disease and with normal portography. Patients with cirrhosis had a median portal pressure of 38 cmH₂O and patients without liver disease had a median portal pressure of 16 cmH₂O. Among the cirrhotic patients the free portal pressure showed no relationship to etiology of cirrhosis, ascites, variceal bleedings or extrahepatic shunting. The median portal pressure was significantly higher in patients with (40 cmH₂O) than without (30 cmH₂O) gastroesophageal varices (p<0.01). The pressure was not related to the size of the varices.     

TVT and TOT: a comparison between these two techniques based on our clinical experience

AIM OF THE STUDY: A retrospective evaluation and a comparison of results from two minimally invasive surgery techniques that we adopted for the treatment of SUI. MATERIALS AND METHODS. In this study we evaluated 113 selected patients who underwent SUI minimally invasive surgery from 1-1-2000 to 31-12-2007. 87 patients underwent epidural anesthesia. 26 local anesthesia. In Group A (TVT) 61 patients were enrolled, mean age 57.6 (±22). 43 patients (70%) were on menopause. In Group B (TOT out-in) 52 patients were enrolled (for 34 of them we used the Obtape? sling while for 18 the Obtryx? one), their mean age was 58.5 (±20.5) and 39 patients (75%) were on menopause. Patients from both groups did not undergo any past previous urogynecological surgery and suffered from stress urinary incontinence with cervico-urethral hypermobility butno other associated pathology. The pre-operative work-up included an evaluation of patients based on ICS guidelines. RESULTS. Group A (TVT) - mean follow-up 66.3 months, dry patients 53/61 (86.8%). Bladder perforations resolved by catheterization 3/61 (5%). Transient voiding dysfunction 14/61 (22.8%). "De novo" urgency 8/61 (13%). One patient on self-catheterization due to persistent urinary retention underwent a single-side section of the sling with spontaneous micturition and complete continence recovery. Group B (TOT out-in) - mean follow-up 35.5 months, dry patients 43/52 (82%). 4 patients (7.6%) complained oftransient voiding dysfunction, 5 patients (9.5%) for "de novo" urgency, 1 patient underwent a sling removal due to vaginal erosion 4 months after surgery (Obtape?).     

Acute Effect of Bronchodilator on Intrathoracic Airway Wall Compliance in COPD Patients

Purpose

In patients with chronic obstructive pulmonary disease (COPD), bronchial responsiveness after acute administration of short acting bronchodilators is conventionally assessed by measuring the improvement of forced expiratory volume in the first second (FEV₁) during a maximal forced expiratory maneuver. This study aimed to measure the variation of intrathoracic airway wall compliance (AWC) after acute administration of short acting beta-2 agonist in COPD patients since this might influence the final modification of airway caliber during maximal expiratory effort and the resulting bronchodilation as inferred by FEV₁ changes.

Methods

In a group of 10 patients suffering from COPD, intrathoracic AWC was measured at middle (50% of Forced Vital Capacity (FVC) and low (75% of FVC) lung volumes using the interrupter method during forced expiratory maneuver in basal conditions and after acute inhalation of albuterol (salbutamol) (400 mcg by MDI). Ten healthy subjects were examined similarly as a control group.

Results

Lower values of baseline intrathoracic AWC at both lung volumes were found in COPD patients (1.72?±?0.20 ml/cmH₂O and 1.08?±?0.20 ml/cmH₂O, respectively) as compared to controls (2.28?±?0.27 ml/cmH₂O and 1.44?±?0.22 ml/cmH₂O, respectively) (p?<?0.001). In COPD patients, AWC increased significantly at both lung volumes after salbutamol, amounting to 1.81?±?0.38 ml/cmH₂O and 1.31?±?0.39 ml/cmH₂O, respectively (p?<?0.01), but the relative change was not different from that observed in controls.

Conclusion

In COPD patients, AWC is reduced compared to controls, but after bronchodilator, the intrathoracic airways become more compliant. The consequent increased collapsibility under high positive pleural pressure could limit the airway caliber improvement seen after bronchodilator, as assessed by the FEV₁ changes during the forced expiratory maneuver, underestimating the effective bronchodilation achieved in these patients.

     

Risk Factors for De Novo Mixed Urinary Incontinence and Stress Urinary Incontinence Following Surgical Removal of a Urethral Diverticulum

Objectives: The aim of the present study was to investigate the risk factors for the development of de novo stress urinary incontinence (SUI) and mixed urinary incontinence (MUI) after surgical removal of a urethral diverticulum (UD). Methods: We identified 35 consecutive women that underwent surgical removal of a UD between November 2002 and December 2009, and we retrospectively reviewed their medical records, including patient demographics, pelvic magnetic resonance imaging (MRI), presenting symptoms related to voiding, and outcomes. Results: Among the 35 patients we identified, 28 were included in the study. After UD removal, five of the 28 patients (17.8%) developed de novo MUI, and four of the 28 patients (14.2%) developed de novo SUI. The incidences of SUI and MUI were significantly higher in patients who had a UD that measured over 3 cm in diameter and in patients in whom the UD was located in the proximal urethra. Of the seven patients with a diverticulum over 3 cm, SUI occurred in three (42.8%) (P = 0.038) and MUI occurred in five (45.4%) (P < 0.001). Of the 11 patients with a diverticulum located in the proximal urethra, SUI occurred in five (45.4%) (P = 0.011) and MUI occurred in four (36.4%) (P = 0.011). Conclusion: Significant risk factors for the development of SUI and MUI after transvaginal simple diverticulectomy include a UD measuring over 3 cm and a UD located in the proximal urethra.     

Efficacy of Clean Intermittent Catheterization for Urinary Incontinence in Children with Neurogenic Bladder Dysfunction Secondary to Myelodysplasia

Objectives: To evaluate the efficacy of clean intermittent catheterization for urinary incontinence in myelodysplastic children. Methods: The cohort comprised of 38 children (19 boys and 19 girls, aged between 10 months to 16 years) with neurogenic bladder secondary to myelodysplasia. Group A included 16 children who had dilated upper urinary tract or vesicoureteral reflux when clean intermittent catheterization was introduced. The remaining 22 children with normal upper urinary tract were enrolled to group B. In the present study, we defined socially acceptable continence as having completely dry or slight stress incontinence that patients can manage with several small pads. Results: Of the 16 group A patients, 9 obtained socially acceptable continence by conservative management. Of the 22 group B patients, 11 reported socially acceptable continence by conservative management. Vesical compliance was significantly higher in cases who reported socially acceptable continence than in those with incontinence persistent regarding all participants (10 ± 7.2 vs 6.8 ± 6.2 mL/cmH₂O, P = 0.0347) and group A (9.1 ± 6.7 vs 3.7 ± 1.4 mL/cmH₂O, P = 0.0350). Leak point pressure was significantly higher in patients who obtained socially acceptable continence than in those having persistent incontinence regarding all participants (50 ± 17.2 vs 25 ± 6.6 mL/cmH₂O, P = 0.0003), group A (51 ± 21.4 vs 26 ± 7.2 mL/cmH₂O, P = 0.0348) and also, group B (49 ± 12.8 vs 23.7 ± 6.3 mL/cmH₂O, P = 0.0043). Conclusion: In our series, socially acceptable continence was obtained in only 20 patients (52%) by conservative management. The present study suggests that the limitation of conservative treatment seems to be apparent when they have urethral closure deficiency and/or intractable poor vesical compliance.     

Severe Thigh Abscess Two Years after Transobturator Sling Operation

Objectives: Tension‐free vaginal tape has gained large popularity owing to the ease of the procedure and its effectiveness. These procedures were initially thought to rarely involve any significant morbid complications. The transobturator tape (TOT) procedure reproduces the natural suspension similar to the tension‐free vaginal tape with a reduction in potential bladder, bowel, and vascular complications by the retropubic approach. However, the TOT procedure is not risk‐free when improperly performed. We report a rare case of abscess formation after TOT. Methods: A 45‐year‐old woman was admitted to the orthopedic department with the chief complaint of right side thigh pain and swelling. Pelvis MRI showed abscess formation and inflammatory changes extending into the soft tissues and muscles between the right gracilis and adductor femoris. During incision and open drainage, the remnant mesh could not be located. On urologic consult, the pelvic examination located the remnant mesh to the right upper vaginal wall. Our patient underwent excision of the mesh material. Results: She had significant improvement of the leg pain and was discharged home in good condition on postoperative day 7. Ultimately, the treatment for this complication was the removal of the mesh. Conclusion: Treatment for thigh abscess after TOT was the removal of the mesh. All patients should be counseled about this potential complication.     

An investigation on the respiratory mechanics of mechanically ventilated patients during spontaneous breathing trials with enhanced low-level pressure support ventilation

Introduction

Low-level pressure support ventilation (PSV) is most commonly adopted in spontaneous breathing trials (SBTs), and some have proposed setting the positive end-expiratory pressure (PEEP) to 0 cmH₂O in order to shorten the observation time of SBTs. This study aims to investigate the effects of two PSV protocols on the patients' respiratory mechanics.

Material and method

A prospective randomized self-controlled crossover design was adopted in this study, which involved enrolling 30 difficult-to-wean patients who were admitted to the intensive care unit of the First Affiliated Hospital of Guangzhou Medical University between July 2019 and September 2021. Patients were subjected to the S group (pressure support: 8 cmH₂O, PEEP: 5 cmH₂O) and S1 group (PS: 8 cmH₂O, PEEP: 0 cmH₂O) for 30 min in a random order, and respiratory mechanics indices were dynamically monitored via a four-lumen multi-functional catheter with an integrated gastric tube. Among the 30 enrolled patients, 27 were successfully weaned.

Result

The S group showed higher airway pressure (Paw), intragastric pressure (Pga) and airway pressure–time product (PTP) than the S1 group. The S group also showed a shorter inspiratory trigger delay, (93.80 ± 47.85) versus (137.33 ± 85.66) ms (P = 0.004); and fewer abnormal triggers, (0.97 ± 2.65) versus (2.67 ± 4.48) (P = 0.042) compared with the S1 group. Stratification based on the causes of mechanical ventilation revealed that under the S1 protocol, patients with chronic obstructive pulmonary disease (COPD) had a longer inspiratory trigger delay compared to both post-thoracic surgery (PTS) patients and patients with acute respiratory distress syndrome. Despite providing greater respiratory support, S group led to significant reductions in inspiratory trigger delay and less abnormal triggers compared to S1 group, especially among patients with chronic obstructive pulmonary disease.

Conclusion

These findings suggest that the zero PEEP group was more likely to induce a higher number of patient–ventilator asynchronies in difficult-to-wean patients.     

Changes in Pulmonary Mechanics after Lung Volume Reduction Surgery

Lung volume reduction surgery (LVRS) is a promising new treatment for emphysema and leads to increased flow rates. We investigated the mechanisms by which flow rates could increase and the correlates of lessened dyspnea in patients undergoing LVRS before and 3 months after LVRS in patients with severe emphysema. The following were done: routine pulmonary function testing, measurements of elastic recoil (Pel), tidal breathing patterns, inspiratory work of breathing (W_insp), construction of static recoil-maximum flow curves, and measurement of baseline and transitional dyspnea index (TDI). There were increases in forced vital capacity (FVC: 2.24 ± 0.71 to 2.92 ± 0.63 liters; p < 0.05), forced expired volume in 1 (FEV₁: 0.64 ± .16 to 1.03 ± 0.28 liters; p < 0.01), and decreases in all divisions of lung volume, e.g. total lung capacity (TLC: 6.86 ± 1.41 to 5.96 ± 1.49 liters; p < 0.01). Maximum Pel increased (11.7 ± 3.7 to 19.8 ± 7.8 cmH₂O; p < 0.02) as did the coefficient of retraction (C_R= Pel/TLC: 1.8 ± 0.7 to 3.6 ± 3.6 ± 2.2 cmH₂O/liter). However, the individual responses in other parameters were markedly different among patients. There was no consistent trend in changes in the slope or position of the static recoil-maximum flow curve or W_insp. The only positive correlate of improved dyspnea (TDI = 3.22 ± 2.22; p < 0.01) was improvement in C_R, FEV₁ being a weak negative correlate and change in lung volume not being a correlate at all. We conclude that there is a heterogeneous response of the airways to LVRS. Increased elastic recoil was the primary determinant of improved flow rates after LVRS and is the only positive correlate for improvement in dyspnea. Accepted for publication: 14 July 1997     

Use of an occlusive penile clamp during filling cystometry in men with symptoms of stress urinary incontinence

Objective: In severe post‐prostatectomy stress urinary incontinence (SUI), urodynamics may not identify crucial parameters because of inadequate bladder filling. This study evaluated cystometry and pressure flow studies (PFS) in men in whom severe SUI during attempted filling necessitated application of a penile clamp to allow filling to reach cystometric capacity. Men who had undergone prior radical prostatectomy were identified from a database of patients attending for video urodynamic testing between 2012 and 2017. Symptom scores, bladder diary and free flow rate tests were retrieved. Measurements of the subgroup of men for whom a Thomson‐Walker compression clamp was used to enable full urodynamic evaluation were evaluated. 166 patients were identified. In 30 patients (18%), severe SUI led to incomplete filling cystometry. Following application of the penile compression clamp, further filling was achieved in each case. Applying the clamp did not alter vesical filling or impede pressure recording. These men had a lower maximum urethral closure pressure (31.6 vs. 46.5 cm H₂O; P < 0.001), volume at strong desire to void (132 vs. 242 mL; P = 0.003) and cystometric capacity (226 mL with clamp applied vs. 310 mL; P < 0.001) than the overall post‐prostatectomy incontinence population. Flow rates during PFS were comparable, but detrusor pressure at maximum flow was lower in the clamp group (11 vs. 22 cm H₂O; P = 0.009). A penile clamp applied at the time when leakage becomes excessive during filling cystometry avoids premature test termination in men with severe incontinence.     

Role of positive end-expiratory pressure changes on functional residual capacity in surfactant treated preterm infants

Both surfactant replacement and positive end-expiratory pressure (PEEP) increase lung volume in infants with respiratory distress syndrome (RDS). We measured pulmonary mechanics and functional residual capacity (FRC) in 21 preterm infants with RDS, > 48 hr post-surfactant therapy (BW, 1,168 ± 441 g; GA, 28.3 ± 2.8 weeks; postnatal age, 3–7 days). A non-linear but significant increase in mean FRC was noted as PEEP increased from 2 to 5 cmH₂O: 18.4 ± 4.7mL/kg at 2 cmH₂O; 19.7 ± 4.3 mL at 3 cm H₂O; 22.6 ± 5.5ml/kg at 4 cmH₂O; and 26.2 ± 6.2 mL/kg at 5 cmH₂O (P < 0.01). Because of the synergistic combined effect on lung volume, surfactant treated neonates should be weaned cautiously from PEEP during ventilatory management. Our study also suggests that the occurrence of inadvertent end-distending pressure during FRC measurement in the ventilated neonate lead to erroneous results. Pediatr Pulmonal. 1994;18:89–92. © 1994 Wiley-Liss, Inc.     

Esophageal variceal pressure influence on the effect of ligation

AIM: To explore the effect of in vitro porcine esophageal variceal pressure on complete ligation degree for polycyclic ligators. METHODS: An in vitro model of experimental porcine venous vessels was used to test various venous pressures. Three treatment groups were designated according to the preset pressure range: P1 = 25-30 cm H2O; P2 = 35-40 cm H2O; P3 = 45-50 cm H2 O. The effect of pressure on ligation was assessed and compared among the groups. RESULTS: Complete ligation was achieved at a rate of 56.25%(18/32) in group P1, 37.5%(12/32) in group P2, and 33.33%(11/33) in group P3(χ2 = 3.6126; P = 0.0573). CONCLUSION: Higher variceal pressures impair the ligation completion rate. Therefore, measuring variceal pressure may help predict the effect of endoscopic ligation and guide treatment choice.     

Influence of lung volume hysteresis on collateral resistance in intact dogs

Collateral resistance (Rcoll) is highly lung volume dependent. We studied 12 dogs in an attempt to evaluate the influence of hysteresis on this volume dependency. Rcoll measurements were obtained at baseline and at different lung volumes as modified by the application of negative or positive extrathoracic pressure (ETP) in an iron lung. ETP was modified in 5 cmH₂O steps from +20 to -25 cmH₂O) and back to +20 cmH₂O on the first day (cycle 1), and, in 4 of these dogs, from -25 to +20 cmH₂O and back to -25 cmH₂O on a second day (cycle 2). The behavior of Rcoll for both cycles was the same in all dogs, varying inversely with the changes in end-expiratory lung volume (EELV). All dogs presented a similar pattern: during cycle 1, for a same lung volume, Rcoll was much higher during the deflation limb than during the inflation limb. For cycle 2, Rcoll at a given lung volume was similar whether measured during the inflation or deflation limb. Changes in EELV were higher for any given negative ETP during the deflation than during the inflation limb of the pressure cycles (e.g., for the 4 dogs who had both cycles, at -15 cmH₂O ETP of cycle 2 the increase in EELV was 1167±121 ml during deflation and 525±102 ml during the subsequent inflation [mean±SEM]). In conclusion, the effects of hysteresis on Rcoll and on lung volumes are similar, except at low lung volumes during the deflation limb of cycle 2. This latter finding could be due to the closure of collateral pathways at a higher lung volume during deflation than during inflation.     

Endotracheal tube cuff pressure change: Proof of concept for a novel approach to objective cough assessment in intubated critically ill patients

PurposeCough strength assessment aids in predicting extubation failure. Peak expiratory flow rate during cough manoeuvre (CPF) is the gold-standard tool and flow rates of <60l/min suggest risk of failed extubation. We aimed to assess endotracheal tube cuff pressure change (ΔP_cuff) as a novel method of objective cough strength assessment in intubated patients considered for extubation.Materials and MethodsPaired measurements of CPF and ΔP_cuff were sampled during cough manoeuvres by intubated recovering critically ill patients. Spearman's correlation was used to assess agreement between the variables. Categorical data and receiver operating characteristic (ROC) curve analysis were undertaken to assess discriminating ability of ΔP_cuff to identify low CPF.ResultsIn total, 42 patients yielded 81 paired measurements. Paired samples with the highest CPF per patient had a correlation coefficient of 0.74. The composite of all samples had a correlation coefficient of 0.77. Regression analysis showed CPF=60l/min equates to ΔP_cuff=28cmH₂O with categorical analysis using these cut-offs showing significant dependence between the variables (p = 0.000001). ROC curve analysis identified an area under the curve (AUC) of 0.9 [95% CI (0.84, 0.97)], with optimal sensitivity and specificity of ΔP_cuff at 20cmH₂O.ConclusionsWe identified a good correlation between CPF and ΔP_cuff. Our research showed that overall discriminating ability of ΔP_cuff in identifying CPF <60l/min was excellent. Further studies, looking at ΔP_cuff and extubation outcomes are required to establish clinical utility.     

Sintering Nano-Silver Paste by Resistive Joule Heating Process for 2G HTS Tape Joints

Developing a joining technology for 2G HTS tapes without significantly reducing their superconducting property is crucial for numerous applications (MRI, motor/generator, power transmission, etc.). In this study, low sintering temperature (~230 °C) nano-silver paste was used as solder to join two 2G HTS tapes. In addition, two heating methods, i.e., furnace heating (heat flux outside-in) and resistive Joule heating (heat flux inside-out), were studied. This study indicates that the heat flux from internal by resistive Joule heating method shows less deteriorating impact to the 2G RE-Ba-Cu-O tape (RE: rare earth element) during the sintering process with the best specific resistance of 0.074 μΩ∙cm² and I_c retention percentage of 99% (i.e., I_c reduced from 100 A before joining to 99 A after joining). This study indicates that nano-silver paste together with resistive Joule heating can possibly be used as soldering materials to join 2G HTS tapes.