BACKGROUND

Breathing circuits connect the ventilator to the patients' respiratory system. Breathing tubes, connectors, and sensors contribute to artificial airway resistance to a varying extent. We hypothesized that the flow-dependent resistance is higher in pediatric breathing systems and their components compared to respective types for adults.

OBJECTIVE

We aimed to characterize the resistance of representative breathing systems and their components used in pediatric patients (including devices for adults) by their nonlinear pressure-flow relationship.

METHODS

We used a physical model to measure the flow-dependent pressure gradient (∆P) across breathing tubes, breathing tube extensions, 90°- and Y-connectors, flow- and carbon dioxide sensors, water traps and reusable, disposable and coaxial breathing systems for pediatric and for adult patients. ∆P was analyzed for usual flow ranges and statistically compared at a representative flow rate of 300 mL∙s-1 (∆P300 ).

RESULTS

∆P across pediatric devices always exceeded ∆P across the corresponding devices for adult patients (all P < .001 [no 95% CI includes 0]). ∆P300 across breathing system components for adults was always below 0.2 cmH2 O but reached up to 4.6 cmH2 O in a flow sensor for pediatric patients. ∆P300 was considerably higher across the reusable compared to the disposable pediatric breathing systems (1.9 vs 0.3 cmH2 O, P < .001, [95% CI -1.59 to -1.56]).

CONCLUSIONS

The resistances of pediatric breathing systems and their components result in pressure gradients exceeding those for adults several fold. Considering the resistance of individual components is crucial for composing a breathing system matching the patient's needs. Compensation of the additional resistance should be considered if a large composed resistance is unavoidable.

UNASSIGNED

What is the central question of this study? Maximal sniff nasal inspiratory and reverse sniff nasal expiratory pressures are measured as inspiratory and expiratory muscle strength, respectively. Is the genioglossus muscle activated during short maximal inspiratory and expiratory efforts through the nose? What is the main finding and its importance? Genioglossus muscle activity occurred with inspiratory muscle activity during a maximal sniff and with expiratory muscle activity during a maximal reverse sniff. These results indicate that genioglossus muscle activity is closely related to the generation of maximal sniff nasal inspiratory and reverse sniff nasal expiratory pressures.

UNASSIGNED

Maximal sniff nasal inspiratory pressure (SNIPmax ) is widely used to assess inspiratory muscle strength. The sniff nasal inspiratory pressure (SNIP) is lower in patients with neuromuscular disease with bulbar involvement compared with those without, possibly owing to impaired upper airway muscle function. However, the degree to which the genioglossus (GG) muscle, one of the upper airway muscles, is activated during inspiratory and expiratory efforts through the nose remains unclear. Therefore, we examined GG activity during short and sharp inspiratory and expiratory efforts through the nose, i.e. sniff and reverse sniff manoeuvres. In eight normal young subjects, we inserted fine wire electrodes into the GG muscle, parasternal intercostal and scalene (inspiratory) muscles and transversus abdominis (expiratory) muscle. We assessed EMG activity of each muscle and measured SNIP and reverse sniff nasal expiratory pressure (RSNEP) during sniffs and reverse sniffs from low to high intensities in the sitting position. The highest SNIP and RSNEP were analysed as SNIPmax and maximal RSNEP (RSNEPmax ), respectively. In each subject, GG EMG activity increased linearly with increasing SNIP and RSNEP. The SNIPmax and RSNEPmax were -85.1 ± 15.9 and 83.2 ± 24.2 cmH2 O, respectively. Genioglossus EMG activity varied with EMG activity of the parasternal intercostal and scalene muscles during generation of SNIPmax and with EMG activity of the transversus abdominis muscle during RSNEPmax . Genioglossus EMG activity during generation of SNIPmax was higher than during RSNEPmax (62.9 ± 31.1% EMG of SNIPmax , P = 0.012). These results suggested that GG activity was closely related to the generation of both SNIPmax and RSNEPmax .

OBJECTIVE

In preterm infants, the application of nasal Continuous Positive Airway Pressure (nCPAP) improves lung function through several mechanisms and may interact with the control of breathing. Our aim was to evaluate the effect of increasing/decreasing nCPAP on gas exchange, breathing pattern, and its variability in preterm infants.

METHODS

Fifeteen infants with mild to moderate respiratory distress syndrome (RDS) were studied on the first day of life. Infants had a mean (SD) gestational age of 30 + 4 (3 + 4) weeks + day and body weight of 1405 (606) g. nCPAP was increased every 10 min stepwise (0-4-8-10 cmH2 O) and then decreased every 20 min (8-6-4-2 cmH2 O). At each step, vital parameters, oxygenation, and chest wall volume changes (optoelectronic plethysmography) were evaluated. Tidal volume (VT ), inter-breath interval (IBI), end-expiratory lung volume (EELV) changes, and other breathing pattern parameters were computed breath-by-breath. The correlation properties of VT , IBI, and EELV were quantified by detrended fluctuation analysis, computing the scaling exponent α.

RESULTS

During nCPAP, oxygenation improved and VT decreased significantly compared with no nCPAP. No significant changes in breathing pattern were observed between nCPAP levels. α of EELV was significantly higher off nCPAP than during nCPAP, suggesting that nCPAP helps stabilize EELV control mechanisms.

CONCLUSIONS

In our population of preterm infants with mild to moderate RDS, in the first day of life, nCPAP improved gas exchange, VT , and EELV stability independent of nCPAP level.

We performed a randomised, controlled, cross-over study of lung ventilation by Basic Life Support-trained providers using either the Tulip GT® airway or a facemask with a Guedel airway in 60 anaesthetised patients. Successful ventilation was achieved if the provider produced an end-tidal CO2>> 3.5 kPa and a tidal volume>> 250 ml in two of the first three breaths, within 60 sec and within two attempts. Fifty-seven (95%) providers achieved successful ventilation using the Tulip GT compared with 35 (58%) using the facemask (p < 0.0001). Comparing the Tulip GT and facemask, the mean (SD) end-tidal CO2 was 5.0 (0.7) kPa vs 2.5 (1.5) kPa, tidal volume was 494 (175) ml vs 286 (186) ml and peak inspiratory pressure was 18.3 (3.4) cmH2 O vs 13.6 (7) cmH2 O respectively (all p < 0.0001). Forty-seven (78%) users favoured the Tulip GT airway. These results are similar to a previous manikin study using the same protocol, suggesting a close correlation between human and manikin studies for this airway device. We conclude that the Tulip GT should be considered as an adjunct to airway management both within and outside hospitals when ventilation is being undertaken by Basic Life Support-trained airway providers.

UNASSIGNED

What is the central question of this study? Does inspiratory resistance breathing improve tolerance to simulated haemorrhage in individuals with elevated internal temperatures? What is the main finding and its importance? The main finding of this study is that inspiratory resistance breathing modestly improves tolerance to a simulated progressive haemorrhagic challenge during heat stress. These findings demonstrate a scenario in which exploitation of the respiratory pump can ameliorate serious conditions related to systemic hypotension.

UNASSIGNED

Heat exposure impairs human blood pressure control and markedly reduces tolerance to a simulated haemorrhagic challenge. Inspiratory resistance breathing enhances blood pressure control and improves tolerance during simulated haemorrhage in normothermic individuals. However, it is unknown whether similar improvements occur with this manoeuvre in heat stress conditions. In this study, we tested the hypothesis that inspiratory resistance breathing improves tolerance to simulated haemorrhage in individuals with elevated internal temperatures. On two separate days, eight subjects performed a simulated haemorrhage challenge [lower-body negative pressure (LBNP)] to presyncope after an increase in internal temperature of 1.3 ± 0.1°C. During one trial, subjects breathed through an inspiratory impedance device set at 0 cmH2 O of resistance (Sham), whereas on a subsequent day the device was set at -7 cmH2 O of resistance (ITD). Tolerance was quantified as the cumulative stress index. Subjects were more tolerant to the LBNP challenge during the ITD protocol, as indicated by a>> 30% larger cumulative stress index (Sham, 520 ± 306 mmHg min; ITD, 682 ± 324 mmHg min; P < 0.01). These data indicate that inspiratory resistance breathing modestly improves tolerance to a simulated progressive haemorrhagic challenge during heat stress.

To study the effect of end-expiratory pressure used during anesthesia on blood loss during radical prostatectomy.

We evaluated 247 patients who underwent either radical retropubic prostatectomy or robot-assisted laparoscopic prostatectomy at a single institution from 2008 to 2013 by one of four surgeons. Patient characteristics were compared using t-tests, rank sum or χ(2) -tests as appropriate. The association between positive end-expiratory pressure and estimated blood loss was tested using linear regression.

Patients were classified into high (≥4 cmH2 O) and low (≤1 cmH2 O) positive-end expiratory pressure groups. Estimated blood loss in radical retropubic prostatectomy was higher in the high positive end-expiratory pressure group (1000 mL vs 800 mL, P = 0.042). Estimated blood loss in robot-assisted laparoscopic prostatectomy was lower in the high positive end-expiratory pressure group (150 mL vs 250 mL, P = 0.015). After adjusting for other factors known to influence blood loss, a 5-cmH2 O increase in positive end-expiratory pressure was associated with a 34.9% increase in estimated blood loss (P = 0.030) for radical retropubic prostatectomy, and a 33.0% decrease for robot-assisted laparoscopic prostatectomy (P = 0.038).

In radical retropubic prostatectomy, high positive end-expiratory pressure was associated with higher estimated blood loss, and the benefits of positive end-expiratory pressure should be weighed against the risk of increased estimated blood loss. In robot-assisted laparoscopic prostatectomy, high positive end-expiratory pressure was associated with lower estimated blood loss, and might have more than just pulmonary benefits.

The choice of prophylactic operation for familial adenomatous polyposis (FAP) is controversial. Colectomy and ileorectal anastomosis (IRA) is a time-honoured procedure but has recently been replaced by restorative proctocolectomy in many centres. The objective of this study was to compare the operative and functional outcomes following IRA and restorative proctocolectomy (RPC). The morbidity rate, operation time, blood loss and hospital stay were compared in 99 IRA and 33 RPC patients. The functional outcome following IRA and RPC were compared in 22 sex-matched pairs. The median hospital stay was 11 days after IRA and 12 days after RPC. The operation time was longer in RPC (216 vs 182 min) and blood loss greater (1253 vs 634 ml). The complication rates were 30% after RPC and 18% after IRA. None of 23 primary RPC operations failed, but two (20%) of the 10 patients with secondary RPC following IRA finally received a permanent ileostomy. The overall functional satisfaction was excellent in 82% and 88% after RPC and IRA, respectively. The mean basal anal pressure was higher in the IRA groups (54 vs 39 cmH2 O, P = 0.004) and the stool frequency slightly less (4.7 vs 5.8, P = 0.06) than after RPC. There is little difference in short-term surgical or functional results between IRA and RPC but a secondary RPC may be unsuccessful. Therefore, primary RPC may be a better option in FAP than IRA.

OBJECTIVE

We explored the feasibility of use of continuous positive airway pressure (CPAP) with 15- and 4-cmH2 O for a randomized controlled trial with patients with pleural drainage.

METHODS

Ten patients with traumatic pleural effusion drained within 24 hr, with controlled pain received randomly CPAP with 0-, 4-, and 15-cmH2 O. Computed tomography was used to assess the lung aeration. Patients reported the level of tolerability. Air leak was also observed as a parameter of safety. The levels of pressure were compared using the Friedman test followed by the Tukey test as post hoc.

RESULTS

The lung area under CPAP with 15 cmH2 O (median = 3,913 mm2 ; IQR = 3,416-4,390 mm2 ) was greater than 4 (median = 3,495 mm2 ; IQR = 3,075-3,954 mm2 ) and 0 cmH2 O (median = 3,382 mm2 ; IQR = 2,962-3,658 mm2 ; p < 0.001). There was no difference between lung areas under CPAP with 4 and 0 cmH2 O. All levels of pressure were well tolerated by patients. No air leak was observed during the assessments.

CONCLUSIONS

CPAP with 15 cmH2 O is able to expand lungs of patients with pleural drainage. CPAP with 4 cmH2 O seems not have therapeutic effect. In addition, CPAP with 15 cmH2 O is well tolerated and safe in this population.

OBJECTIVE

This study aimed to compare the outcomes of pelvic floor muscle training (PFMT) between postpartum and non-postpartum women with stress urinary incontinence (SUI) and to detect potential factors that may influence these outcomes.

METHODS

A total of 54 and 79 participants were recruited into postpartum (PP group) and non-postpartum (non-PP group) groups, respectively. A physiotherapist treated the participants twice a week for 6-8 weeks. At baseline and 6 and 12 months after treatment, the 1-h pad weight test (PWT), vaginal contraction pressure (VCP), and Incontinence Impact Questionnaire Short Form (IIQ-7) were assessed by an evaluator or physiotherapist. The primary outcome was PWT improvement. The participants whose PWT improvement reached a >50% reduction relative to baseline were considered responders. Secondary outcomes included VCP, IIQ-7 score, and patient satisfaction rate.

RESULTS

The PWT improvement was 87.04% (95%CI: 0.78, 0.96) in the PP group at 1-year follow-up, which was significantly better than the 72.15% improvement (95%CI: 0.62, 0.82) in the non-PP group (OR = 2.591, 95%CI: 1.018, 6.595, P = 0.041). Changes in VCP and BMI were significant predictors of responders in the regression analysis. As the change in VCP increased by 1 cmH2 O, the efficiency increased by 4.2% (OR = 1.042, 95%CI: 1.010, 1.070). The change in BMI increased by 1 kg/m2 , and the efficiency decreased 23.0% (OR = 0.770, 95%CI: 0.633, 0.937).

CONCLUSIONS

The outcome of PFMT in postpartum participants with SUI was better than that in non-postpartum participants. Women with more improvements in VCP and weight loss showed better amelioration of SUI symptoms after PFMT.

The objective of this study was to determine failure pressures of 6 rhinologic repair techniques of large skull base/dural defects in a controlled, ex vivo model.

Failure pressures of 6 dural repairs in a porcine model were studied using a closed testing apparatus; 24-mm × 19-mm dural defects were created; 40-mm × 34-mm grafts composed of porcine Duragen (Integra), fascia lata, and Biodesign (Cook) were used either with or without Tisseel (Baxter International Inc.) to create 6 repairs: Duragen/no glue (D/NG), Duragen/Tisseel (D/T), fascia lata/no glue (FL/NG), fascia lata/Tisseel (FL/T), Biodesign/no glue (B/NG), and Biodesign/Tisseel (B/T). Saline was infused at 30 mL/hour, applying even force to the underside of the graft until repair failure. Five trials were performed per repair type for a total of 30 repairs.

Mean failure pressures were as follows: D/NG 1.361 ± 0.169 cmH2 O; D/T 9.127 ± 1.805 cmH2 O; FL/NG 0.200 ± 0.109 cmH2 O; FL/T 7.833 ± 2.657 cmH2 O; B/NG 0.299 ± 0.109 cmH2 O; and B/T 2.67 ± 0.619 cmH2 O. There were statistically significant differences between glued (Tisseel) and non-glued repairs for each repair category (p < 0.05).

All glued repairs performed better than non-glued repairs. Both D/T and FL/T repairs performed better than B/T repairs. No repair tolerated pressures throughout the full range of adult supine intracranial pressure.

Previous studies have shown that 2-deoxy-d-glucose (2-DG) increases gastric motility via the vagus nerve, but the underlying mechanism remains elusive. Since nitric oxide (NO) is involved in gastric motility, a possible interplay between 2-DG and NO can be suggested. In the present study, Wistar rats (250-350 g) of both sexes were intravenously injected with 2-DG (200 mg/kg), and the effects of the intravenous injection of the nitric oxide synthase (NOS) inhibitors; nitro-l-arginine methyl ester (l-NAME, 10 mg/kg) and Nω -nitro-l-arginine (l-NNA, 10 mg/kg) were investigated. Animals were anaesthetized and cannulated for intravenous drug injections while the left vagal nerve was electrically stimulated (0.1-10 Hz, 0.5 ms duration, 12 V, for 60 seconds), and intragastric pressure and gastric motility changes were monitored using a latex gastric balloon. 2-DG increased the mean intragastric pressure (baseline, 5.0±0.4 cmH2 O; after 2-DG, 14.4±1.5 cmH2 O; P=.0156) and significantly increased the gastric motility index, while NOS inhibitors significantly attenuated both parameters. However, pretreatment with NOS inhibitors significantly augmented the gastric responses to peripheral electrical vagal stimulation. These results suggest that NO plays an excitatory role in gastric responsiveness to 2-DG and that this function may be effected in the central nervous system.

BACKGROUND

We hypothesized that anesthetized, apneic children could be ventilated equivalently or more efficiently by nasal mask ventilation (NMV) than face mask ventilation (FMV). The aim of this randomized controlled study was to test this hypothesis by comparing the expiratory tidal volume (Vte) between NMV and FMV.

METHODS

After the induction of anesthesia, 41 subjects, 3-17 years of age without anticipated difficult mask ventilation, were randomly assigned to receive either NMV or FMV with neck extension. Both groups were ventilated with pressure control ventilation (PCV) at 20 cmH2 O of peak inspiratory pressure (PIP) with positive end-expiratory pressure (PEEP) levels of 0, 5, and 10 cmH2 O. An additional mouth closing maneuver (MCM) was applied for the NMV group.

RESULTS

The Vte was higher in the FMV group compared with the NMV group (median difference [95% CI]: 8.4 [5.5-11.6] ml·kg(-1) ; P < 0.001) when MCM was not applied. NMV achieved less PEEP than FMV (median difference [95% CI]: 5.0 [4.3-5.3] cmH2 O at 10 cmH2 O; P < 0.001) though both groups achieved the set PIP level. In the NMV group, MCM markedly increased Vte (median increase [95% CI]: 5.9 [2.5-9.0] ml·kg(-1) ; P < 0.005) and PEEP (median increase [95% CI]: 5.0 [0.6-8.6] cmH2 O at 10 cmH2 O; P < 0.005); however, PEEP was highly variable and lower than that of FMV (median difference [95% CI]: 2.5 [0.8-8.5] cmH2 O at 10 cmH2 O; P < 0.05).

CONCLUSIONS

In anesthetized, apneic children greater than 2 years of age ventilated with an anesthesia ventilator and neck extension, FMV established a greater Vte than NMV regardless of mouth status. NMV could not maintain the set PEEP level due to an air leak from the mouth. The MCM increased the Vte and PEEP.

OBJECTIVE

To evaluate whether filling phase urodynamic parameters can predict the success of the artificial urinary sphincter (AUS) in treating post-prostatectomy incontinence (PPI).

METHODS

We reviewed the pre-AUS urodynamics of 99 patients with PPI at two tertiary referral centers. We documented the peak DO pressure (Pdet ), capacity, and compliance (C). We defined success as patient-reported continence or only using one safety pad. Patients' perception of improvement was assessed using the PGI-I score.

RESULTS

Sixty-eight percent (n = 68) of patients had a successful outcome. The mean compliance for the "success" and "failure" group was 112.3 mL/cmH2 O (±119.7) and 34.1 mL/cmH2 O (±36.2), respectively. Fifty-five percent (17/31) of patients in the "failure" group demonstrated DO(Pdet = 36.2 ± 18.2 cmH2 O) compared to 18% (12/68) in the success group. The differences between the two groups in Pdet and compliance were statistically significant (all P < 0.01). There was, however, no statistical difference between the mean cystometric capacities of patients in the two outcome groups. Thirteen out of 18 (72%) patients who had radiotherapy had a poor outcome ("success" group only 15% [9/59]). These results were used to develop a nomogram for the probability of AUS success. A good inverse correlation (r = -0.65) was demonstrated between the probability of AUS success as deduced from the nomogram and PGI-I score post-AUS implantation CONCLUSION: Compliance and Pdet are predictors of outcome following AUS implantation for PPI. We have developed and internally validated a nomogram that may be used to determine an individualized likelihood of AUS success. This nomogram may be used as a counseling tool to objectively set realistic expectations of continence post-AUS implantation.

Adult respiratory distress syndrome or ARDS as coined by Ashbaugh et al in 1967, has been a great challenge in the field of critical care since then. It is a clinical entity which can be caused by various insults at any age. There have been several case reports of ARDS involving infants and children in the past 10 years, but pediatric ARDS is still not well recognized in Taiwan. A review of admissions to the pediatric intensive care unit in the past 2 years shows that 11 of the cases were included as pediatric ARDS combined with the expanded definition of Murray et al, and that each patient had an acute lung injury score greater than 2.5. Clinical manifestations also presented acute pulmonary distress indicating ARDS. The distribution of age ranged from 13 months to 11 years. The predisposing insults included sepsis, gastrointestinal bleeding with shock and massive blood transfusion, central nervous system infection, major trauma, near drowning, fulminant hepatitis and chemotherapy for acute leukemia. All received mechanical ventilatory support. The average peak inspiratory pressure was 46.7 +/- 6.4 cmH2O and the mean value of maximal PEEP used was 11.9 +/- 4.4 cmH2 O. Three patients developed barotrauma. Two patients survived and nine expired, a mortality rate of 82%. It is important for physicians caring for infants and children with respiratory failure to consider the diagnosis and initiate adequate ventilatory support and other resuscitation management.

We studied the effects of tracheal tube cuffs filled with air, saline or alkalinised lidocaine on haemodynamic changes during tracheal extubation and postoperative laryngotracheal morbidity in children. We randomly allocated 164 children aged 3-13 years undergoing general anaesthesia to one of four groups; tracheal tube cuffs filled with air (n = 41); saline (n = 41); alkalinised lidocaine 0.5% (n = 41); or alkalinised lidocaine 1% (n = 41). Intracuff pressure was monitored and maintained below 20 cmH2 O. The mean (SD) increases in systolic blood pressure after tracheal extubation compared with before extubation were 10.9 (10.8) mmHg, 7.3 (17.7) mmHg, 4.1 (10.5) mmHg and 1.9 (9.5) mmHg in the air, saline, 0.5% and 1% alkalinised lidocaine groups, respectively (p = 0.021). The mean (SD) increases in diastolic blood pressure after tracheal extubation compared with before extubation were 3.9 (9.7) mmHg, 7.9 (14.6) mmHg, 0.7 (10.4) mmHg and 3.6 (6.9) mmHg in the air, saline, 0.5% and 1% alkalinised lidocaine groups, respectively (p = 0.019). The mean (SD) increases in heart rate after tracheal extubation compared with before extubation were 14.2 (7.6) beats.min-1 , 15.5 (13.1) beats.min-1 , 5.2 (9.6) beats.min-1 and 4.1 (6.6) beats.min-1 in the air, saline, 0.5% and 1% alkalinised lidocaine groups, respectively (p < 0.001). The incidence of sore throat 8 h after tracheal extubation was 22.0% in the air-filled group, 9.8% in the saline group, 4.9% in the 0.5% alkalinised lidocaine group and 2.4% in the 1% alkalinised lidocaine group, p = 0.015. We conclude that filling the tracheal tube cuff with alkalinised lidocaine-filled reduces the haemodynamic response to tracheal extubation and postoperative laryngotracheal morbidity in children.

OBJECTIVE

To investigate the effect of tadalafil on bladder blood flow and lower urinary tract function in a rat model of diabetes.

METHODS

We studied female Sprague-Dawley rats and induced diabetes in some using a single intraperitoneal injection of streptozotocin. We divided the rats into nondiabetes (ND), diabetes (D), and diabetes with tadalafil (DT) groups. The rats were raised for an additional 7 weeks after diabetes induction. The DT group received oral tadalafil (2 mg/kg/day) for 7 days before the experiments. At 7 weeks after diabetes induction, we performed cystometry, resected the bladders for immunohistochemistry (hypoxia-inducible factor-1α [HIF-1α] and 8-oxo-2'-deoxyguanosine [8-OHdG] staining), and measured bladder blood supply using a laser blood flow meter.

RESULTS

The opening pressure, when the urethra opens and urine flow starts, was significantly lower in the DT group than in the D group (24.9 ± 5.9 vs 43.6 ± 12.3 cmH2 O). The inter-contraction interval was significantly longer in the D group than in the ND and DT groups (1566.2 ± 168.7 vs 702.9 ± 165.2 and 787.4 ± 148.8 s). Immunohistochemistry showed positive staining of the urothelial layer for both HIF-1α and 8-OHdG in the D group, but not in the ND or DT groups. Bladder blood flow was significantly lower in the D group than in the ND or DT groups.

CONCLUSIONS

Tadalafil improves bladder blood supply and lower urinary tract function in diabetic rats. Tadalafil may be a promising drug that restores lower urinary tract dysfunction in the early phase of diabetes.

BACKGROUND

Oscillatory pressure (ΔP) measurement during high frequency oscillatory ventilation (HFOV) is technically challenging and influenced by all the components of the measurement system.

OBJECTIVE

To evaluate the differences between the ΔP delivered at the inlet of the endotracheal tube and those displayed by commercial neonatal mechanical ventilators and monitoring devices and to characterize how the ventilator circuit and the flowmeter proximal to the patient affect these differences.

METHODS

Six devices were evaluated while ventilating three mechanical analogues representing the newborn respiratory system in different disease states. ΔP measured at different points of the ventilator circuit were compared.

RESULTS

ΔP accuracy is highly variable and decreases with increasing oscillation frequency and amplitude, independently of the mean airway pressure. At 15 Hz, a ΔP displayed by ventilators of 40 cmH2 O resulted in a ΔP effectively delivered at the tracheal tube ranging from 22 to 49 cmH2 O, depending on the ventilator model, the ventilator circuit, and the patient condition. At these settings, the errors exclusively due to the ventilator circuit and the presence of the flowmeter ranged from 6 to 9 cmH2 O and from 1 to 6 cmH2 O, respectively.

CONCLUSIONS

The ventilator model, the breathing circuit, the flowmeter, and the patient condition severely impacts ΔP measurement accuracy during HFOV, leading to highly variable performances. This prevents the possibility of using the ΔP required to normalize gas exchange as an indicator of patients' condition, complicates comparison of ventilators performances, and adds a significant element of complexity in clinical management of HFOV.

Leakage of colonised oropharyngeal secretions across the tracheal tube cuff may cause iatrogenic pulmonary infection. We studied a novel 'add-on' cuff, which can be inserted over an existing tracheal tube and advanced into the subglottic region. The physical properties of the novel silicone cuff (BronchoGuard, Ciel Medical, USA) were evaluated in comparison with the Hi-Lo® tracheal tube. In a bench study, we identified saline inflation volumes required to transmit pressures between 15 and 30 cmH2 O against artificial tracheas of 18, 20 and 22 mm internal diameter. We computed cuff compliance, and minimal inflation volume to achieve air sealing during mechanical ventilation. Finally, we compared the leakage flow rate of artificial saliva across the novel cuff. On average, the mean (SD) inflation volumes necessary to transmit tracheal pressures of 15, 20, 25 and 30 cmH2 O were 4.1 (2.2), 4.4 (2.3), 4.6 (2.4) and 4.8 (2.4) ml for the novel cuff and 7.7 (2.5), 8.0 (2.6), 8.4 (2.6) and 8.7 (2.7) ml for the Hi-Lo tube, respectively (p < 0.001). The minimal inflation volumes to achieve air sealing were 3.8 (0.9) and 10.5 (2.1) ml (p < 0.001), which resulted in transmitted tracheal pressures of 8.3 (9.8) and 27.6 (34.8) cmH2 O (p < 0.001). Compliance was 0.026 (0.004) and 0.616 (0.324) ml.cmH2 0-1 , respectively (p < 0.001). Although massive leak was found when the novel cuff transmitted pressures ≤ 20 cmH2 O against the trachea, leakage was avoided with pressures ≥ 25 cmH2 O, owing to optimal contact between the cuff and the tracheal wall. In contrast, the standard cuff consistently leaked irrespective of the pressure. We conclude that the novel cuff has advantageous properties that warrant clinical corroboration.

This paper expands a previous study on functional analysis of high frequency jet (HFJV) "Ergojet CVT" ventilation module inserted in Ergotronic 3 (Temel SA) respirator. The analysis was made on a pulmonary monoalveolar model with a compliance of 50 ml/cmH2 = and a resistance of 20 cmH2O/l/se simulating an obstructive pattern. Results were also compared with those obtained in a previous study on normal lung. HFJV was applied using a jet with or without additional gas input (VE) at respiratory rates of 90, 120, 150, 180, 210, 240, 270, and 300 per minute varying in each frequency the releasing pressure of the jet (PG 1, 2, and 3 kg/cm2) and the inspiratory time (Ti 30 to 50%) giving rise to a total of 96 different situations. In each of these conditions we measured the air way pressure (Paw) and the alveolar pressure (PA) and we calculated the tidal volume (VT) and the trapped volume (VAT). These measurements were correlated with those monitored by the respirator and those obtained in the normal lung. Results show that the VT is composed almost exclusively by the jet volume (VTjet), being only of consideration the VE with a Ti of about 33% and a PG of 2 to 3 kg/cm2. When the normal pattern was compared with the obstructive one, a small reduction in VT (average of 15%) and a marked increase in peak Paw (average of 75%) were observed. The use of a Ti of 50% has no clinical interest due to the large VAT that it produces.(ABSTRACT TRUNCATED AT 250 WORDS)

OBJECTIVE

To investigate the significance of the ice water test in patients with multiple sclerosis and to evaluate a novel ice water test nomogram in a large patient cohort.

METHODS

A total of 201 ice water tests of patients with multiple sclerosis were retrospectively evaluated. Incontinence episodes in 24 h and sex were correlated with the ice water test. Furthermore, an ice water test nomogram was developed in order to categorize the detrusor overactivity in severity degrees. Descriptive statistics were carried out for population characteristics. Correlations of categorical variables were calculated by the χ2 -test. The independent t-test was carried out for correlations of continuous variables. Furthermore, the data were evaluated in the novel ice water test nomogram.

RESULTS

The patient population consisted of 141 (70.1%) women and 60 (39.9%) men. A clinically positive ice water test (maximum detrusor pressure >15 cmH2 O) was identified in 75 patients (37.3%). Significantly more men presented a clinically positive ice water test (P = 0.006). In 16.5%, the ice water test unmasked an involuntary detrusor contraction, although routine cystometry did not show any detrusor overactivity. The ice water test nomogram could be successfully applied. The incontinence episodes and maximum detrusor pressure correlated positively with a higher categorization in the nomogram. Therapeutic interventions and follow-up controls could be successfully illustrated by the nomogram.

CONCLUSIONS

The ice water test is a simple tool for unmasking non-identified detrusor overactivity in neurogenic bladder dysfunction. A severity categorization of the detrusor overactivity can be facilitated by the use of the ice water test nomogram. After further validation, the ice water test could be ultimately used in future as objective assessment for bladder dysfunction.

OBJECTIVE

Ketamine abuse may cause variable lower urinary tract symptoms and severe cystitis. In this study, we evaluated the relevance of urodynamic parameters according to the dose and duration of ketamine use and investigate the value of urodynamic studies in determining the severity of ketamine-associated cystitis (KC).

METHODS

The urodynamic study results of 30 patients with KC between January 2009 and December 2012 were analyzed retrospectively. All patients had been diagnosed based on their history and clinical features before urodynamic investigations. Cystoscopy was performed to confirm the diagnosis and measure the maximum anesthetic bladder bladder capacity (MBC) (under spinal anesthesia).

RESULTS

The mean (± standard deviation) age of patients with KC was 22.0 ± 3.3 years. The mean duration of ketamine abuse was 39.0 ± 20.8 months. Maximum cystometric capacity was 115 ± 66.6 mL. Seventy-five percent of patients had a high maximal urethral closure pressure (MUCP) >> 90 cmH2 O). There was no significant difference of urodynamic parameters between the high-dose (≥ 5 gm/day) and low-dose groups (< 5 gm/day) or the long-duration (≥ 3 years) and short-duration (< 3 years) groups. However, the MBC was significantly lower in high-dose and long-duration groups compared to the low-dose and short-duration groups (191.3 ± 68.5 vs. 299.0 ± 99 mL; P = 0.01; 219.0 ± 59.7 vs. 325.5 ± 104.5 mL; P = 0.002).

CONCLUSIONS

The urodynamic test results help diagnose KC, but may not be useful in determining the severity of the disease. The MBC measured under anesthesia may be a better predictor of the disease progression in KC.

OBJECTIVE

Pressure flow studies are regarded as the gold standard for evaluating both bladder outlet obstruction and detrusor contractility, but none of the current methods for evaluating bladder contraction patterns are well validated. Impaired bladder contraction results in a lower peak Watts factor and poorly sustained detrusor contractions. From this viewpoint, the maximum Watts factor and its pattern should be considered separately. To examine detrusor contraction pattern in patients after radical prostatectomy by using multiple parameters.

METHODS

A total of 37 patients with clinically localized prostate cancer underwent both pre- and post-radical prostatectomy urodynamic evaluations. The examined urodynamic parameters included the maximum flow rate, post-void residual volume, detrusor pressure at maximum flow, maximum Watts factor and relative volume (maximum Watts factor). Some parameters were defined from the Watts factor curve throughout micturition. Relative volume (maximum Watts factor) was the relative bladder volume at the maximum Watts factor. A normal detrusor contractility pattern involves an increase in Watts factor at the initiation followed by further gradual increases until the end of micturition.

RESULTS

Maximum flow rate increased significantly after radical prostatectomy (pre: 13.0 ± 6.5, post: 17.3 ± 7.7 mL/min; P < 0.01), whereas detrusor pressure at maximum flow and post-void residual volume decreased significantly (pre: 49.6 ± 21.6 and 31.4 ± 18.2 cmH2 O; post: 48.6 ± 66.1 and 10.1 ± 28.5 mL; P < 0.05). Maximum Watts factor did not change significantly after radical prostatectomy (pre: 10.5 ± 3.1 W/m2 , post: 11.0 ± 3.2 W/m2 ), but relative volume (maximum Watts factor) decreased significantly (pre: 0.48 ± 0.3, post: 0.20 ± 0.20; P < 0.001). Maximum Watts factor represents the maximum power of bladder contraction at a particular point in time, whereas relative volume (maximum Watts factor) can be used to detect changes in detrusor contraction pattern.

CONCLUSIONS

Evaluation of relative volume (maximum Watts factor) confirms that radical prostatectomy restores the normal detrusor contractility pattern in prostate cancer patients.

Research has suggested that sighs may serve a regulatory function during stress and emotions by facilitating relief. Evidence supports the hypotheses that sighs both express and induce relief from stress. To explore the potential role of sighs in the regulation of symptoms, the present study aimed to investigate the relationship between sighs and relief of symptoms, and relief of dyspnea, specifically. Healthy volunteers participated in two studies (N = 44, N = 47) in which dyspnea was induced by mild (10 cmH2 O/l/s) or high (20 cmH2 0/l/s) inspiratory resistances. Dyspnea relief was induced by the offset of the inspiratory resistances (transitions from high and mild inspiratory resistance to no resistance). Control comparisons included dyspnea increases (transitions from no or mild inspiratory resistance to high inspiratory resistance) and dyspnea continuations (continuations of either no resistance or a high resistance). In Experiment 1, dyspnea levels were cued. In Experiment 2, no cues were provided. Sigh rate during dyspnea relief was significantly higher compared to control conditions, and sigh rate increased as self-reported dyspnea decreased. Additionally, sigh rate was higher during cued dyspnea relief compared to noncued dyspnea relief. These results suggest that sighs are important markers of dyspnea relief. Moreover, sighs may importantly express dyspnea relief, as they are related to experiential dyspnea decreases and occur more frequently during expected dyspnea relief. These findings suggest that sighs may not only be important in the regulation of stress and emotions, but also may be functional in the regulation of dyspnea.

BACKGROUND

Inspiratory esophagogastric junction (EGJ) pressure is lower in gastroesophageal reflux disease (GERD) and patients fail to increase EGJ pressure during the inspiratory effort. The aim of this study was to assess the EGJ activity during inspiratory maneuvers (high-resolution manometry, HRM) and the crural diaphragm (CD) thickness (endoscopic ultrasound, EUS) in GERD.

METHODS

Twenty esophagitis patients (average age 45 years, 7 grade A, 13 grade B) had HRM and EUS. Forty-three controls were recruited; 30 had HRM (average age 33 years), and 13 had EUS (average age 40 years). The EGJ contractility index (EGJ-CI) (mm Hg×cm) was measured during normal respiration and two inspiratory maneuvers: without and with inspiratory loads of 12, 24, and 48 cmH2 O (TH-maneuvers). A composite metric for TH-maneuvers ("EGJ total activity") was defined as the product of the maximal EGJ pressure and the length of its aboral excursion during the maneuver (mm Hg×cm). The CD thickness (cm) was measured during expiration (12 MHz).

RESULTS

Expiratory lower esophageal sphincter pressure and integrated relaxation pressure were lower in GERD. The EGJ-CI and the "EGJ total activity" were lower in GERD during TH-maneuvers (48-cmH2 O load: 168.4 ± 13.8 vs 114.8 ± 9.6, P=.006). Patients failed to sustain the inspiratory CD activity across the 12 and 48-cmH2 O efforts. The CD was thinner in GERD patients (0.37 ± 0.03 vs 0.49 ± 0.04, P=.02). The CD thickness correlated with the increment in the "EGJ total activity" in GERD without a hiatal hernia (r=.702, P=.016, n=11).

CONCLUSIONS

There are anatomical changes and functional failure of the CD in esophagitis patients supporting the possibility of a skeletal muscle deficiency in GERD.