BACKGROUND

Clinical characteristics such as oropharyngeal leak pressure (OLP) and ventilation peak pressure are important factors for successful use of supraglottic airway devices in general anaesthesia. We hypothesized that the LMA Protector™ compared to the LMA Supreme™ may develop a higher OLP, which could be of clinical significance.

METHODS

Ninety-six patients were randomized to the LMA Protector™ or LMA Supreme™ groups. We measured oropharyngeal leak pressure within 5 minutes after insertion of the supraglottic airway device with a standardized cuff pressure at 60 cm H2 O. Secondary parameters, such as insertion time of the supraglottic airway device, the number of attempts inserting the supraglottic airway device and the gastric tube, volume of gastric contents, and maximum airway pressure, as well as pulse oximetry throughout the operation were measured. Further, blood staining after removal of the supraglottic airway device and postoperative airway morbidity 3 hours after surgery were determined.

RESULTS

The mean difference of oropharyngeal leak pressure was 5.2 (95% CI 2.8-7.6), ie, 30.9 (7.4) cmH2 O for the LMA Protector™ vs 25.6 (4.4) cmH2 O for the LMA Supreme™ (P < 0.001; mean(SD)). Similarly, there was a mean difference between OLP and maximal ventilation peak pressure 5.6 (95% CI 3.1-8.2) ie 19.6 (7.7) cmH2 O for the LMA Protector™ vs 14.0 (4.4) cmH2 O for the LMA Supreme™ (P < 0.001). No difference was found between the groups for other secondary parameters, as well as postoperative airway morbidity.

CONCLUSIONS

The LMA Protector™ enabled a higher OLP compared to the LMA Supreme™. This finding may be important for patients requiring a higher peak pressure for sufficient supraglottic airway device ventilation.

OBJECTIVE

To evaluate the effects of continuous positive airway pressure (CPAP) on intrapulmonary shunt, cardiac output and oxygen delivery in horses subjected to a 6 hour period of general anaesthesia.

METHODS

Randomized, experimental, crossover study.

METHODS

Ten healthy adult horses.

METHODS

Following medetomidine, diazepam and ketamine administration, orotracheal intubation was performed and horses positioned in dorsal recumbency. Anaesthesia was maintained with isoflurane carried in an oxygen and air mix (FiO2 0.5) combined with a medetomidine infusion. Horses were anaesthetized twice and either CPAP (8 cmH2 O) or physiologic airway pressure (NO CPAP) was applied to the lungs for 6 hours; the order of treatments was randomly assigned. Following induction of anaesthesia, cardiovascular and respiratory variables (including arterial blood gas analysis) were recorded every 30 minutes, cardiac output was measured every 60 minutes using the lithium dilution technique and oxygen delivery calculated. If PaCO2 exceeded 100 mmHg (13.3 kPa), controlled ventilation was initiated and horses excluded from further data collection. Groups were compared using a general linear model.

RESULTS

Data from eight horses were analysed. PaO2 was 15-56 mmHg (2.00-7.45 kPa) higher (p < 0.001) and shunt fraction 6-14% lower (p < 0.001) in the CPAP group. No differences were seen for cardiac output and oxygen delivery. The lack of difference in oxygen delivery was attributed to lower haemoglobin levels in the CPAP group than in the NO CPAP group.

CONCLUSIONS

CPAP of 8 cmH2 O can be used in dorsally recumbent horses to decrease pulmonary shunt fraction without causing a decrease in cardiac output during longterm anaesthesia.

Assessment of respiratory muscle strength provides important diagnostic and prognostic information. Normative data in healthy, term infants is, however, limited. Surgically correctable birth defects, congenital diaphragmatic hernia (CDH) and abdominal wall defects (AWD), commonly have impaired diaphragm function. The study aims were to obtain normative data for respiratory muscle strength in healthy, term born infants at birth and at 6 weeks postnatal age (PNA) and to investigate the influence of growth and maturation on inspiratory muscle strength in CDH/AWD infants. Maximal inspiratory (cPimax) and expiratory (cPemax) pressures during crying were measured at birth in 67 healthy, term born infants (mean (SD) gestational age (GA) 39.4 (1.7) weeks) and reassessed in 27 at 6 weeks PNA. cPimax and functional residual capacity (FRC) (22.3 (4.2) ml/kg) were also measured in 23 infants with AWD/CDH (mean (SD) GA 36.9 (2.1) weeks) and reassessed in 16 at median (range) 6.5 (1.5-15) months PNA. In healthy infants, mean (SD) cPimax was 88.8 (19.33) cmH2 O and cPemax 61.8 (13.5) cmH2 O at birth, increasing significantly at followup to 100.9 (15.2) cmH2 O (P < 0.05) and 82.6 (19.4) cmH2 O (P < 0.001) respectively. Mean (SD) cPimax was significantly lower (47.5 (22.4) cmH2 O, P < 0.0001) in AWD/CDH infants compared to healthy infants at birth but had increased significantly to 88.1 (27.6) cmH2 O (P < 0.0001) at followup which correlated significantly with increases in FRC (r(2) = 0.33, P = 0.0263). Infants with AWD and CDH have significantly reduced inspiratory muscle strength compared to healthy term born infants but strength increases markedly in early life.

To investigate the effects of propofol and isoflurane on urethral pressure profilometry of female dogs and goats, and to identify the method of anesthesia that least influences urethral pressure profilometry and to assess its reproducibility.

The effects of premedication with midazolam, propofol sedation and isoflurane anesthesia were assessed in five female dogs. The effects of propofol and isoflurane were compared in seven goats, whereas in another group of 19 goats, the state of deep propofol sedation was compared with the state of recovery from propofol sedation. The coefficient of reproducibility and within-subject coefficient of variation were calculated to evaluate test-retest reproducibility.

In conscious female dogs, maximal urethral closure pressure and functional area were significantly higher than under propofol or isoflurane (P = 0.04), but not different from the recovery state. In six of seven goats, maximal urethral closure pressure and functional area were higher when measured under propofol sedation than under isoflurane (median maximal urethral closure pressure, 69 vs 47 cmH2 O; P = 0.03). Maximal urethral closure pressure was lower under propofol than during recovery from propofol in 17 of 19 goats (median maximal urethral closure pressure, 54 vs 66 cmH2 O; P < 0.001). The test-retest coefficient of reproducibility for goats was 28 cmH2 O, and the within-subject coefficient of variation was 16%.

In dogs, urethral pressure profilometry should be measured in conscious animals whenever possible. In goats, urethral pressure profilometry is least affected during recovery from propofol sedation, and it shows acceptable reproducibility under this condition.

BACKGROUND

Equine asthma is a disease characterised by reversible airflow obstruction, bronchial hyper-responsiveness and airway inflammation following exposure of susceptible horses to specific airborne agents. Although clinical remission can be achieved in a low-airborne dust environment, repeated exacerbations may lead to irreversible airway remodelling. The available data on the pharmacotherapy of equine asthma result from several small studies, and no head-to-head clinical trials have been conducted among the available medications.

OBJECTIVE

To assess the impact of the pharmacological interventions in equine asthma and compare the effect of different classes of drugs on lung function.

METHODS

Pair-wise and network meta-analysis.

METHODS

Literature searches for clinical trials on the pharmacotherapy of equine asthma were performed. The risk of publication bias was assessed by funnel plots and Egger's test. Changes in maximum transpulmonary or pleural pressure, pulmonary resistance and dynamic lung compliance vs. control were analysed via random-effects models and Bayesian networks.

RESULTS

The results obtained from 319 equine asthma-affected horses were extracted from 32 studies. Bronchodilators, corticosteroids and chromones improved maximum transpulmonary or pleural pressure (range: -8.0 to -21.4 cmH2 O; P<0.001). Bronchodilators, corticosteroids and furosemide reduced pulmonary resistance (range: -1.2 to -1.9 cmH2 O/L/s; P<0.001), and weakly increased dynamic lung compliance. Inhaled β2 -adrenoreceptor (β2 -AR) agonists and inhaled corticosteroids had the highest probability of being the best therapies. Long-term treatments were more effective than short-term treatments.

UNASSIGNED

Weak publication bias was detected.

CONCLUSIONS

This study demonstrates that long-term treatments with inhaled corticosteroids and long-acting β2 -AR agonists may represent the first choice for treating equine asthma. Further high quality clinical trials are needed to clarify whether inhaled bronchodilators should be preferred to inhaled corticosteroids or vice versa, and to investigate the potential superiority of combination therapy in equine asthma.

To clarify the involvement of bladder α1-adrenoceptors (α1-ARs) in afferent pathways by investigating the effects of silodosin and BMY7378, selective α1A- or α1D-AR antagonists, respectively, on single-unit afferent nerve fibre activity (SAA) of the primary bladder afferent nerves and their relationship with bladder microcontractions in rats.

A total of 63 female Sprague-Dawley rats were anaesthetized with urethane. The SAA of Aδ and C fibres generated from the left L6 dorsal roots was determined using electrical stimulation of the left pelvic nerve and bladder distension. After measuring baseline SAA during constant filling cystometry, the procedure was repeated with i.v. (0.3-30 μg/kg) or intravesical (10 μm) administration of each antagonist. In separate rats, the bladder was filled with saline until the intravesical pressure reached 30 cmH2 O, and was kept under isovolumetric conditions, then the recording was performed with i.v.-administered vehicle and silodosin (0.3 μg/kg).

A total of Aδ fibres and 33 C fibres were isolated from 63 rats. The SAA of Aδ fibres, but not C fibres, were dose-dependently decreased after both i.v. and intravesical administrations of each of the antagonists. In the experiments under bladder isovolumetric conditions, silodosin administration significantly decreased the SAA of Aδ fibres, but not C fibres, compared with vehicle administration. There were no significant effects on either the mean basal bladder pressure or microcontractions.

The present study suggests that both α1A- or α1D-ARs in the rat bladder are involved in the activation of the bladder mechanosensory Aδ fibres during bladder filling, and that this activation may not be related to bladder microcontractions.

OBJECTIVE

To analyse the mid-term safety and efficacy of the ALTIS® single-incision sling (Coloplast Corp., Minneapolis, MN, USA) for female stress urinary incontinence (SUI).

METHODS

We conducted a prospective, single-arm, unsponsored, observational single-centre trial in a cohort of patients undergoing SUI surgery with the ALTIS procedure. All patients were diagnosed according to clinical reports, physical exploration and urodynamics. Body mass index (BMI) was categorised according to World Health Organization classification. Valsalva leak-point pressure (VLPP) was categorised in three groups: <60, 60-90 and >90 cmH2 O. Patients were evaluated postoperatively at 1, 6, 12 and 24 months with physical examination, International Consultation on Incontinence Questionnaire Short Form (ICIQ-SF), and satisfaction visual scale (SVS; score 0-10). Adverse events were assessed at each visit. Multivariate analysis for risk factors of surgery failure was performed.

RESULTS

We recruited 110 women, with a mean (SD) follow-up of 22.34 (10.34) months. Regarding efficacy, 91 patients (82.7%) were objectively cured and 97 (88.2%) were subjectively cured. Regarding VLPP and BMI, no differences were seen between groups (P>> 0.05). There was a ~20% decrease in urge UI (P = 0.04). No variable showed to be an independent risk factor for ALTIS failure (P>> 0.05). Overall, nearly 96% of the women reported 9 or 10 points on the SVS. A total of 24 patients (21.8%) had some kind of complication. No mesh erosion was reported in any patient.

CONCLUSIONS

The ALTIS sling demonstrated to be an effective and safe procedure for SUI in the mid-term setting. Objective and subjective cure rates are at least comparable to 'gold standard' procedures with a minimal rate of self-limiting non-surgical complications.

OBJECTIVE

To examine the outcomes of lower urinary tract symptoms (LUTS) and urodynamic test results after cerebrospinal fluid (CSF) shunt surgery in idiopathic normal pressure hydrocephalus (iNPH).

METHODS

Records of 48 patients (33 men; 15 women), who met the definite iNPH criteria and underwent CSF shunt surgery, were retrospectively analyzed. LUTS and their impact on quality of life (QOL) were evaluated using an all-or-none questionnaire targeting four symptoms, the Overactive Bladder Symptoms Score (OABSS), and the QOL index. Urodynamic investigations included filling cystometry and pressure-flow studies performed before and after surgery.

RESULTS

Forty-seven (98%) patients complained of LUTS, 41 (87%) patients of whom experienced LUTS improvement after surgery. The OABSS and QOL index, which before surgery were 6.8 ± 0.7 and 4.1 ± 0.4, respectively, significantly decreased to 4.6 ± 0.6 and 3.2 ± 0.3, respectively, after surgery. The maximum cystometric capacity (174.9 ± 13.3 mL to 222.4 ± 14.7 mL) and bladder compliance (35.8 ± 4.4 ml/cmH2 O to 52.1 ± 5.4 ml/cmH2 O) significantly increased after surgery. Detrusor overactivity, which was observed in 37 (77%) patients preoperatively, became undetectable in 7 patients postoperatively. Voiding dysfunction (defined as maximum flow rate <10 mL/s or post-void residual >100 mL) was observed in 29 (60%) patients, 22 (75%) of whom had detrusor underactivity before surgery. None of the voiding urodynamic parameters significantly improved postoperatively.

CONCLUSIONS

iNPH is often associated with LUTS and both storage and voiding dysfunctions. CSF shunt surgery improved LUTS and storage dysfunction, with limited effects on voiding dysfunction.

OBJECTIVE

Air-charged (AC) and water-perfused (WP) catheters have been evaluated for differences in measuring pressures for voiding dysfunction. Typically, a two-catheter system was used. We believe that simultaneous pressure measurements with AC and WP in a single catheter will provide analogous pressures for coughs, Valsalvas, and maximum pressures in voiding pressure studies (VPS).

METHODS

This IRB approved prospective study included 50 women over age 21. AC dual TDOC catheters were utilized. The water-filling channel served as the bladder filler and the water pressure readings. Patients were evaluated with empty bladders and at volumes of 50-100 mL, 200 mL, and maximum capacity with cough and Valsalva maneuvers. Comparative analysis was performed on maximum stress peak pressures. At maximum bladder capacity, VPS was done and maximum voiding pressure was recorded.

RESULTS

Comparing coughs and Valsalva maneuvers pressures, there was significant increase in variability between AC and WP measurements with less than 50 mL volume (P < 0.001). Significant correlations were observed between AC and WP measurements for coughs and Valsalvas with bladder volume over 50 mL. Visual impression showed virtually identical tracings. Cough measurements had an average difference of 0.25 cmH2 O (±8.81) and Valsalva measurements had an average difference of 3.15 cmH2 O (±4.72). Thirty-eight women had usable maximum voiding pressure measurements and had a strong correlation.

CONCLUSIONS

Cystometrogram and maximum voiding pressure measurements done with either water or air charged catheters will yield similarly accurate results and are comparable. Results suggest more variability at low bladder volumes <50 mL.

OBJECTIVE

To assess the predictive value of a simple clinical test (posterior vaginal wall pull down maneuver) in the diagnosis of intrinsic sphincter deficiency.

METHODS

The present prospective study included 62 women suffering from stress urinary incontinence. Every patient underwent a urogynecological examination including multichannel urodynamic testing (cystometry, urethral pressure profile, Valsalva Leak Point Pressure measurement) and a clinical examination including posterior vaginal wall pull down maneuver. Posterior vaginal wall pull down maneuver was carried out with the bladder filled with 400 mL of saline in a supine position, and was obtained by means of a split speculum allowing gentle pull down traction of the posterior vaginal wall. Posterior vaginal wall pull down maneuver was considered as positive when a urine leak was observed during the manoeuvre. Intrinsic sphincter deficiency was urodynamically defined by maximum urethral closure pressure ≤20 cmH2 O. Correlations between positive/negative posterior vaginal wall pull down maneuver and urodynamic intrinsic sphincter deficiency were calculated.

RESULTS

There was a statistical correlation between age and low maximum urethral closure pressure (P < 0.0001), and between low maximum urethral closure pressure and positive posterior vaginal wall pull down maneuver (P < 0.0001). Regarding the intrinsic sphincter deficiency diagnosis, the posterior vaginal wall pull down maneuver positive predictive value was 94.67% and the negative predictive value was 95.4%, with a specificity of 97.6% and sensitivity of 90%.

CONCLUSIONS

Posterior vaginal wall pull down maneuver is a reliable clinical test, easy to carry out, inexpensive and without significant risk. This test allows the diagnosis of intrinsic sphincter deficiency in women suffering from stress urinary incontinence, thus avoiding further invasive urodynamic testing (urethral pressure profile, Valsalva Leak Point Pressure measurement) in women with genuine stress urinary incontinence. Furthermore, it is helpful when choosing the type of sling procedure (retropubic vs transobturator) when a surgery is planned.

BACKGROUND

High airway pressures, necessary to keep equine lungs open, can have a detrimental impact on central and peripheral perfusion.

OBJECTIVE

The aim of this study was to assess the effects of stepwise increasing airway pressure recruitment on central and intestinal perfusion and oxygenation during isoflurane anaesthesia in horses.

METHODS

In vivo experimental study.

METHODS

Ten anaesthetised horses were ventilated using intermittent positive pressure ventilation immediately after induction. After 90 min, end-expiratory pressure (PEEP) was increased by steps of 5 cmH2 O every 10 min up to a PEEP of 30 cmH2 O and decreased back to zero maintaining a constant airway pressure difference of 20 cmH2 O. Mean arterial blood pressure (MAP), heart rate, central venous pressure, pulmonary artery pressure, expiratory isoflurane concentration and cardiac output (thermodilution method) were measured. Cardiac index (CI) was calculated. Arterial blood gases were taken to measure arterial partial oxygen pressure (PaO2 ) and calculate arterial oxygen saturation (SaO2 ). Intestinal microperfusion and oxygenation were measured by laser Doppler flowmetry and white-light spectrophotometry. After ventral median laparotomy, a probe was placed on the stomach, jejunum and pelvic flexion of the colon. An ANOVA for repeated measurements and Tukey's post hoc test were used for statistical analysis (α = 5%).

RESULTS

Recruitment of the lungs resulted in a significant increase in PaO2 from 201 ± 58 mmHg (baseline) to a maximum of 495 ± 75 mmHg. The CI and MAP decreased continuously with increasing airway pressures. When CI and MAP were 37 ± 9 ml/kg/min and 52 ± 8 mmHg (at PEEP of 25 cmH2 O), respectively, a sudden decrease in intestinal perfusion followed by a delayed decrease in oxygenation occurred.

CONCLUSIONS

There was linear correlation between airway pressures and CI and MAP but not between central and gastrointestinal perfusion. Despite improvement of arterial oxygenation the decrease in CI and, therefore, in oxygen delivery PEEP resulted in a decrease in gastrointestinal oxygenation.

We examined whether urine reflux into the prostate can induce prostatic inflammation in a rat and evaluated the effect of α1-adrenoreceptor antagonist.

Experiment 1: Male Sprague-Dawley rats were injected with 500 µl of Evans Blue through the urethral orifice. Intravesical pressure was measured, and the prostate was excised to evaluate urine reflux. Experiment 2: Rats were injected with 500 µl urine or saline (control) from the urethral orifice. Silodosin (200 µg/kg/day) was administered to the silodosin group. We evaluated histopathology, the expression of proinflammatory cytokines and oxidative stress markers of the prostate on day 7, after assessing the prostatic microcirculation and cystometrogram.

Experiment 1: The histopathology showed that Evans Blue instilled through the urethral orifice entered the prostatic ducts. Intravesical pressure during Evans Blue instillation was 47.7 ± 1.6 cmH2 O (mean ± standard error). Experiment 2: On day 7 after urine instillation through the urethral orifice, histopathology showed infiltrated inflammatory cells in the peri-glandular stroma. Inflammation-associated proteins (IL-1α, IL-1β, IL-6, and TNFα) were upregulated in the urine-instilled rats but not in the silodosin group. Erythrocyte speed on the prostatic surface, immunostaining for hypoxyprobe, and quantification of oxidative stress markers (MDA and HIF-1α) demonstrated prostatic hypoxia in the urine-instilled rats, which was ameliorated in the silodosin group. Cystometrogram revealed a shorter intercontraction interval in the urine-instilled rats, which was prolonged in the silodosin group.

Urine reflux into the prostatic duct induces abacterial prostatitis. Silodosin relieved prostatic inflammation and bladder overactivity by increasing microcirculation in the prostate. Prostate 77:164-172, 2017. © 2016 Wiley Periodicals, Inc.

This study compared two methods of controlling the intracuff pressure in laryngeal mask airways. One hundred and eighty patients were randomly assigned into two groups. In the first group (n = 90), after training, the intracuff pressure was controlled using digital palpation of the pilot balloon. In the second group (n = 90), continuous manometry was used to control the intracuff pressure. An upper pressure limit of 60 cmH2 O was set. The median (IQR [range]) intracuff pressure in the palpation group was 130 (125-130 [120-130]) cmH2 O compared with 29 (20-39 [5-60]) cmH2 O in the manometry group (p < 0.001). In the palpation group, 37% of patients experienced pharyngolaryngeal complications vs. 12% in the manometry group (p < 0.001). We conclude that the digital palpation technique is not a suitable alternative to manometry in controlling the intracuff pressure in laryngeal mask airways.

BACKGROUND

We recently reported that a high respiratory rate was associated with less inflammation than a low respiratory rate, but caused more pulmonary edema in a model of ARDS when an ARDSNet ventilatory strategy was used. We hypothesized that an open lung approach (OLA) strategy would neutralize the independent effects of respiratory rate on lung inflammation and edema. This hypothesis was tested in an ARDS model using two clinically relevant respiratory rates during OLA strategy.

METHODS

Twelve piglets were subjected to an experimental model of ARDS and randomized into two groups: LRR (20 breaths/min) and HRR (40 breaths/min). They were mechanically ventilated for 6 h according to an OLA strategy. We assessed respiratory mechanics, hemodynamics, and extravascular lung water (EVLW). At the end of the experiment, wet/dry ratio, regional histology, and cytokines were evaluated.

RESULTS

After the ARDS model was established, Cdyn,rs decreased from 21 ± 3.3 to 9.0 ± 1.8 ml/cmH2 O (P < 0.0001). After the lung recruitment maneuver, Cdyn,rs increased to the pre-injury value. During OLA ventilation, no differences in respiratory mechanics, hemodynamics, or EVLW were observed between groups. Wet/dry ratio and histological scores were not different between groups. Cytokine quantification was similar and showed a homogeneous distribution throughout the lung in both groups.

CONCLUSIONS

Contrary to previous findings with the ARDSNet strategy, respiratory rate did not influence lung inflammatory response or pulmonary edema during OLA ventilation in experimental ARDS. This indicates that changing the respiratory rate when OLA ventilation is used will not exacerbate lung injury.

BACKGROUND

Although anorectal transplantation is a challenging procedure, it is a promising option for patients who have completely lost anorectal function or in whom it failed to develop, as in congenital malformations. The paucity of animal models with which to test functional outcomes was addressed in this study of anorectal manometry in rats.

METHODS

Wistar rats were assigned randomly to four groups: orthotopic anorectal transplantation, heterotopic transplantation, sham operation, or normal control. Bodyweight and anal pressure were measured immediately before and after operation, and on postoperative days 7 and 14. ANOVA and Tukey's test were used to compare results for bodyweight, anal manometry and length of procedure.

RESULTS

Immediately after the procedure, mean(s.d.) anal pressure in the orthotopic group (n = 13) dropped from 31·4(13·1) to 1·6(13·1) cmH2 O (P < 0·001 versus both sham operation (n = 13) and normal control (n = 15)), with partial recovery on postoperative day 7 (14·9(13·9) cmH2 O) (P = 0·009 versus normal control) and complete recovery on day 14 (23·7(12·2) cmH2 O). Heterotopic rats (n = 14) demonstrated partial functional recovery: mean(s.d.) anal pressure was 26·9(10·9) cmH2 O before operation and 8·6(6·8) cmH2 O on postoperative day 14 (P < 0·001 versus both sham and normal control).

CONCLUSIONS

Orthotopic anorectal transplantation may result in better functional outcomes than heterotopic procedures. Surgical relevance Patients with a permanent colostomy have limited continence. Treatment options are available, but anorectal transplantation may offer hope. Some experimental studies have been conducted, but available data are currently insufficient to translate into a clinical option. This paper details functional outcomes in a rat model of anorectal autotransplantation. It represents a step in the translational research that may lead to restoration of anorectal function in patients who have lost or have failed to develop it.

BACKGROUND

Numerous studies have investigated the best method of selecting the appropriate size of endotracheal tube (ETT) for children. However, none of the methods or formulae for selection of ETT size have shown better prediction over another, and they have required complex formulae calculation or even use of cumbersome equipment. Recursive partitioning analysis creates a decision tree that is more likely to enable clearer and easier visualization of decision charts compared to other data mining methods.

OBJECTIVE

The aim of the current study was to develop a clinically practical and intuitive chart for prediction of ETT size.

METHODS

Pediatric patients aged 2-9 years undergoing general anesthesia were intubated with uncuffed ETT. The tube size was considered optimal when a tracheal leak was detected at an inflation pressure between 10 and 25 cmH2 O. The observed ETT size was compared with the predicted ETT size calculated using Cole's formula, multivariate regression analysis, ultrasonographic measurements, and recursive partitioning tree structure analysis. Preference among the prediction methods was also investigated by asking physicians about their preference of methods.

RESULTS

Correct prediction rates were 33.3%, 50%, 61.9%, and 59.5%, and close prediction rates were 61.9%, 83.3%, 88.1%, and 93.7% for Cole's formulae, multivariate regression analysis, ultrasonographic measurements, and recursive partitioning tree model, respectively. Fourteen of 16 physicians prefer to use the easy-to-interpret tree model.

CONCLUSIONS

Analysis of the tree model by recursive partitioning structure analysis accomplished a high correct and close prediction rate for selection of an appropriate ETT size. The intuitive and easy-to-interpret tree model would be a quick and helpful tool for selection of an ETT tube for pediatric patients.

Findings from manikin-based studies on ventilation are commonly directly extrapolated to clinical practice. The aim of this study was to determine how the use of manikins affects measurements of ventilatory variables. We connected a lung simulator to a manikin, which was then ventilated at different inspiratory flows. We defined three experimental models to compare measurements of ventilatory variables between the mechanical ventilator and the lung simulator. Even when no leakage occurred, significant tidal volume deviations were observed; from a mean (SD) of 21 (2) ml to 49 (9) ml, and from 40 (4) ml to 88 (5) ml for invasive and non-invasive ventilation, respectively (p < 0.001). Significant peak pressure deviations from 0.7 (0.1) cmH2 O to 10.6 (0.3) cmH2 O were also recorded during non-invasive ventilation (p < 0.001). Evaluation of manikin resistance and airway dead space may be essential to limit study bias. We suggest a recalibration of the recorded data if comparisons are made between different tests performed at different inspiratory flows.

OBJECTIVE

The effect of non-invasive ventilation (NIV) in acute severe asthma is unclear and there are concerns regarding its safety.

METHODS

We undertook a 5-year case-control review of mortality and morbidity associated with NIV use in acute severe asthma and compared this with asthma requiring invasive mechanical ventilation (IMV) and a control group with less severe asthma without ventilatory support.

RESULTS

Eight hundred seventy-three patients had acute severe asthma of whom 30 were treated with NIV, 17 with IMV and 90 served as controls. The mean duration of NIV was 9.5 ± 7.3 h with inspiratory positive airway pressure and expiratory positive airway pressure of 11.9 ± 1.4 and 5.8 ± 1.2 cmH2 O respectively. Mortality was zero in the NIV and control groups, compared with 41% in the IMV group. None of the NIV or control groups required escalation to invasive ventilation. There were no instances of haemodynamic compromise in the NIV or control groups. Length of hospital stay was 121 ± 96 h in the NIV group and similar to the severe IMV group (136 ± 99 h, P>> 0.05) and significantly longer than the control group (42 ± 40 h, P < 0.05).

CONCLUSIONS

NIV can be safely used in acute severe asthma although further work is needed to delineate the precise patient selection process.

We investigated the involvement of the 14-residue thrombin receptor activating peptide SFLLRNPNDKYEPF (TRAP-14) in mediating the pulmonary vasoconstriction in response to alpha-thrombin. Isolated guinea pig lungs were uniformly perfused with Ringer-albumin solution at a constant flow of 28 ml/min. Addition of TRAP-14 or human alpha-thrombin to the perfusate caused dose-dependent increases of pulmonary arterial pressure within 1 min. TRAP-14 at 1 microM increased pulmonary arterial pressure to a similar extent as 10 nM alpha-thrombin (i.e., increase of 7.7 +/- 0.8 and 7.4 +/- 0.9 cmH2(0) from baseline, respectively). The increases in pulmonary venous resistance induced by TRAP-14 and alpha-thrombin were two- to fivefold greater than the increases in pulmonary arterial resistance, indicating that both agonists mediated pulmonary hypertension secondary to pulmonary venoconstriction. Stimulation of cultured guinea pig pulmonary artery smooth muscle cells with 100 microM TRAP-14 or 10 nM alpha-thrombin increased cytosolic Ca2+ concentration about five- to sevenfold over baseline. The increase in cytosolic Ca2+ concentration in smooth muscle cells was not observed with a subsequent challenge with either agonist, indicating desensitization. In the perfused lungs, an initial stimulation with alpha-thrombin or TRAP-14 desensitized the lungs to either agonist. The alpha-thrombin-desensitized lungs remained refractile to alpha-thrombin after 1 h of perfusion with fresh Ringer solution, whereas the TRAP-14-desensitized lungs recovered 79% of the vasoconstrictor response by 10 min and 93% of the response by 30 min.(ABSTRACT TRUNCATED AT 250 WORDS)

BACKGROUND

During anaesthetic induction with a facemask, the inconsistent inspiratory flow with manual ventilation (MV) raises the peak airway pressure (PAP), which can be significantly higher than PAP during pressure-controlled ventilation (PCV). In this study, PAP was compared between MV and PCV at the same tidal volume of 8-10 ml/kg during facemask ventilation for anaesthetic induction in children. The occurrence of gastric insufflation (GI) was evaluated with ultrasonography and stethoscopic auscultation.

METHODS

Forty-eight children, aged 0.5-7 years, undergoing elective urologic surgery were randomly allocated into either Group MV or Group PCV. Under light sedation with thiopental iv., ultrasonography (US) was performed and the gastric antrum was identified. After additional thiopental and rocuronium administration, facemask ventilation with a tidal volume of 8-10 ml/kg was performed for 3 min, whereas respiratory parameters were recorded at 1 min intervals. Real-time US and stethoscopic auscultation were performed for evaluation of GI.

RESULTS

In the MV group, PAP was higher at all the time points compared with the PCV group (14 vs. 9.5, 15 vs. 10 and 15 vs. 9 cmH2 O, all P < 0.05). However, there was no difference in the GI occurrence between Group MV and Group PCV (7 vs. 3, P = 0.284). There was no difference between PAP in patients with GI and without GI (P>> 0.05). Ultrasonography was more sensitive in detecting GI than the stethoscopic auscultation (10 vs. 5). Gastric antral area was expanded after facemask ventilation in both groups, but there were no intergroup differences.

CONCLUSIONS

Although PCV provided lower PAP than MV at the same tidal volume, the risk of GI may not be eliminated during facemask ventilation in paralysed small children.

To evaluate the effect of positive end-expiratory pressure (PEEP) on sound propagation through injured lungs, we injected a multifrequency broad-band sound signal into the airway of eight anesthetized, intubated and mechanically ventilated pigs, while recording transmitted sound at three locations bilaterally on the chest wall. Oleic acid injections effected a severe pulmonary oedema predominately in the dependent lung regions, with an average increase in venous admixture from 19 ± 15 to 59 ± 14% (P < 0.001), and a reduction in dynamic respiratory system compliance from 34 ± 7 to 14 ± 4 ml cmH2 O(-1) (P < 0.001). A concomitant decrease in sound transit time was seen in the dependent lung regions (P < 0.05); no statistically significant change occurred in the lateral or non-dependent areas. The application of PEEP resulted in a decrease in venous admixture, increase in respiratory system compliance and return of the sound transit time to pre-injury levels in the dependent lung regions. Our results indicate that sound transmission velocity increases in lung tissue affected by permeability-type pulmonary oedema in a manner reversible during alveolar recruitment with PEEP.

UNASSIGNED

What is the central question of this study? Higher levels of positive end-expiratory pressure (PEEP) have recently been used in patients with acute respiratory distress syndrome (ARDS). In normal physiological conditions, the ability of the diaphragm to generate pressure is reduced when the lung volume is elevated beyond its functional residual capacity. It is unknown whether higher levels of PEEP will have a negative impact on diaphragmatic contraction in the presence of the pathophysiology of ARDS. What is the main finding and its importance? Mechanical ventilation with higher levels of PEEP reduced lung injury, improved diaphragmatic contractility and increased the expression of both dihydropyridine receptor and ryanodine receptor in the diaphragms of rats with ARDS. Higher levels of positive end-expiratory pressure (PEEP) have recently been used in patients with acute respiratory distress syndrome (ARDS). In normal physiological conditions, the ability of the diaphragm to generate pressure is reduced when the lung volume is elevated beyond its functional residual capacity. Thus, it is critical to understand whether higher levels of PEEP will have a negative impact on diaphragmatic contraction in the presence of the pathophysiology of ARDS. This study was designed to determine whether higher levels of PEEP reduce diaphragmatic contractility in a rat model of ARDS generated using i.p. lipopolysaccharide. Forty rats were randomly assigned to the following five groups: a control group with no special treatment; an ARDS group with no mechanical ventilation; and three ARDS groups with mechanical ventilation with PEEP at 0, 5 or 10 cmH2 O, respectively. We found that mechanical ventilation with PEEP reduced lung injury, improved diaphragmatic contractility and increased the expression of both dihydropyridine receptor and ryanodine receptor in the diaphragms of rats with ARDS. These changes were most significant at a PEEP of 10 cmH2 O among all applied levels of PEEP. In conclusion, using a rat ARDS model, this study confirmed that diaphragmatic contractility was preserved by mechanical ventilation with high levels of PEEP.

Primary graft dysfunction occurs in up to 25% of patients after lung transplantation. Contributing factors include ventilator-induced lung injury, cardiopulmonary bypass, ischaemia-reperfusion injury and excessive fluid administration. We evaluated the feasibility, safety and efficacy of an open-lung protective ventilation strategy aimed at reducing ventilator-induced lung injury. We enrolled adult patients scheduled to undergo bilateral sequential lung transplantation, and randomly assigned them to either a control group (volume-controlled ventilation with 5 cmH2 O, positive end-expiratory pressure, low tidal volumes (two-lung ventilation 6 ml.kg-1 , one-lung ventilation 4 ml.kg-1 )) or an alveolar recruitment group (regular step-wise positive end-expiratory pressure-based alveolar recruitment manoeuvres, pressure-controlled ventilation set at 16 cmH2 O with 10 cmH2 O positive end-expiratory pressure). Ventilation strategies were commenced from reperfusion of the first lung allograft and continued for the duration of surgery. Regular PaO2 /FI O2 ratios were calculated and venous blood samples collected for inflammatory marker evaluation during the procedure and for the first 24 h of intensive care stay. The primary end-point was the PaO2 /FI O2 ratio at 24 h after first lung reperfusion. Thirty adult patients were studied. The primary outcome was not different between groups (mean (SD) PaO2 /FI O2 ratio control group 340 (111) vs. alveolar recruitment group 404 (153); adjusted p = 0.26). Patients in the control group had poorer mean (SD) PaO2 /FI O2 ratios at the end of the surgical procedure and a longer median (IQR [range]) time to tracheal extubation compared with the alveolar recruitment group (308 (144) vs. 402 (154) (p = 0.03) and 18 (10-27 [5-468]) h vs. 15 (11-36 [5-115]) h (p = 0.01), respectively). An open-lung protective ventilation strategy during surgery for lung transplantation is feasible, safe and achieves favourable ventilation parameters.

Thirty females, aged 25-50 years old, scheduled for abdominal total hysterectomy were randomly divided to two groups. For patients in group I, 2 mL 1% lidocaine solution was injected through the catheter on the tube to desensitize the trachea while surgeon started to close the peritoneum. In group II, 2 mL 2% lidocaine was used. The peak cuff pressures generated in the awakening group I patients were 49.0 +/- 2.5 cmH2 O (mean +/- SD) which shows greater than that in group II (27.9 +/- 7.2 cmH2 O), p less than 0.01. Bucking before awakening was also evaluated clinically. One hundred % (15/15) in group I patients bucked compared with 13.3% (2/15) in group II patients (p less than 0.01). Gag reflex was preserved in all patients and none suffered from aspiration postoperatively. Intratracheal administration of two mL 2% lidocaine through the catheter of modified endotracheal tube showed significant effect for suppressing bucking during recovery of general anesthesia.