Dead-space reduction and tracheal pressure measurements using a coaxial inner tube in an endotracheal tube

OBJECTIVE: To evaluate the effects on CO(2) washout of the coaxial double lumen tube (DLT) as compared to a standard endotracheal tube (ETT) and tracheal gas insufflation (TGI). Precision of tracheal pressure monitoring through the DLT and safety issues, including intrinsic PEEP (PEEPi) formation during DLT ventilation, were also evaluated. DESIGN: Lung model study. SETTING: University research laboratory. MEASUREMENTS AND RESULTS: CO(2) washout was analysed in a lung model by measuring single alveolar CO(2) concentration during DLT ventilation as compared to standard ETT ventilation, at different minute ventilation (6-14 l/min) and different CO(2)-output levels (180 ml/min, 240 ml/min, and 300 ml/min). At a CO(2) output level of 240 ml/min the CO(2) washout was also compared to tidal volume-adjusted continuous TGI and expiratory synchronised TGI. Precision of tracheal pressure monitoring and PEEPi formation during DLT ventilation was evaluated by comparing pressure in each limb above the tube to reference tracheal pressure, varying I:E ratios (1:2, 1:1, and 2:1), tidal volumes (300-700 ml), breathing frequencies (15-25), and compliance (20-50 ml/cmH(2)O). DLT ventilation had the same efficacy in removing CO(2) as continuous and expiratory synchronised TGI, reducing single alveolar CO(2) concentration by 9-21% compared to normal ventilation. Tracheal pressure could be measured through the DLT with high precision. There was only marginal formation of PEEPi at tidal volumes 相似文献   

Evaluation of a Pitot Type Spirometer in Helium/Oxygen Mixtures

Objective. Mixtures of helium and oxygen are regaining a place in the treatment of obstruction of the upper and lower respiratory tract. The parenchymal changes during the course of IRDS or ARDS may also benefit from the reintroduction of helium/oxygen. In order to monitor and document the effect of low-density gas mixtures, we evaluated the Datex AS/3 Side Stream Spirometry module with D-lite® (Datex-Engstrom Instrumentarium Corporation, Finland) against two golden standards. Methods. Under conditions simulating controlled and spontaneous ventilation with gas mixtures of He (approx. 80, 50, and 20%)/O2 or N2 (approx. 21 and 79%)/O2, simultaneous measurements using Biotek Ventilator Tester (Bio-Tek Instr., Vermont, USA) or body plethysmograph (SensorMedics System, Anaheim, USA) were correlated with data from the spirometry module. Data were analyzed according to a statistical regression model resulting in a best-fit equation based on density, voltage, and volume measurements. Results. As expected, the D-lite (a modified Pitot tube) showed density-dependent behaviour. Regression equations and percentage deviation of estimated versus measured values were calculated. Conclusion. Measurements with the D-lite using low-density gases are satisfactorily contained in best-fit equations with a standard deviation of less than 5% during all ventilatory modes and mixtures.     

Defining sepsis on the wards: results of a multi‐centre point‐prevalence study comparing two sepsis definitions

Our aim was to prospectively determine the predictive capabilities of SEPSIS‐1 and SEPSIS‐3 definitions in the emergency departments and general wards. Patients with National Early Warning Score (NEWS) of 3 or above and suspected or proven infection were enrolled over a 24‐h period in 13 Welsh hospitals. The primary outcome measure was mortality within 30 days. Out of the 5422 patients screened, 431 fulfilled inclusion criteria and 380 (88%) were recruited. Using the SEPSIS‐1 definition, 212 patients had sepsis. When using the SEPSIS‐3 definitions with Sequential Organ Failure Assessment (SOFA) score ≥ 2, there were 272 septic patients, whereas with quickSOFA score ≥ 2, 50 patients were identified. For the prediction of primary outcome, SEPSIS‐1 criteria had a sensitivity (95%CI) of 65% (54–75%) and specificity of 47% (41–53%); SEPSIS‐3 criteria had a sensitivity of 86% (76–92%) and specificity of 32% (27–38%). SEPSIS‐3 and SEPSIS‐1 definitions were associated with a hazard ratio (95%CI) 2.7 (1.5–5.6) and 1.6 (1.3–2.5), respectively. Scoring system discrimination evaluated by receiver operating characteristic curves was highest for Sequential Organ Failure Assessment score (0.69 (95%CI 0.63–0.76)), followed by NEWS (0.58 (0.51–0.66)) (p < 0.001). Systemic inflammatory response syndrome criteria (0.55 (0.49–0.61)) and quickSOFA score (0.56 (0.49–0.64)) could not predict outcome. The SEPSIS‐3 definition identified patients with the highest risk. Sequential Organ Failure Assessment score and NEWS were better predictors of poor outcome. The Sequential Organ Failure Assessment score appeared to be the best tool for identifying patients with high risk of death and sepsis‐induced organ dysfunction.     

Continuous on-line measurements of respiratory system, lung and chest wall mechanics during mechanic ventilation

OBJECTIVE: We present a concept of on-line, manoeuvre-free monitoring of respiratory mechanics during dynamic conditions, displaying calculated alveolar pressure/volume curves continuously and separating lung and chest wall mechanics. DESIGN: Prospective observational study. SETTING: Intensive care unit of a university hospital. PATIENTS: Ten ventilator-treated patients with acute lung injury. INTERVENTIONS: Different positive end-expiratory pressure (PEEP) and tidal volumes, low flow inflation. MEASUREMENTS AND RESULTS: Previously validated methods were used to present a single-value dynostatic compliance for the whole breath and a dynostatic volume-dependent initial, middle and final compliance within the breath. A high individual variation of respiratory mechanics was observed. Reproducibility of repeated measurements was satisfactory (coefficients of variations for dynostatic volume-dependent compliance: < or =9.2% for total respiratory system, < or =18% for lung). Volume-dependent compliance showed a statistically significant pattern of successively decreasing compliance from the initial segment through the middle and final parts within each breath at all respiratory settings. This pattern became more prominent with increasing PEEP and tidal volume, indicating a greater distension of alveoli. No lower inflection point (LIP) was seen in patients with respiratory rate 20/min and PEEP at 4 cmH2O. A trial with low flow inflation in four of the patients showed formation of a LIP in three of them and an upper inflection in one. CONCLUSIONS: The monitoring concept revealed a constant pattern of successively decreasing compliance within each breath, which became more prominent with increasing PEEP and tidal volume. The monitoring concept offers a simple and reliable method of monitoring respiratory mechanics during ongoing ventilator treatment.     

Cardiopulmonary function in former girl swimmers and the effects of physical training.

Sixteen former girl swimmers were studied in 1971 before and after 12 weeks of physical training. These girls constituted a representative selection from a group of 30 girls swimmers studied in 1961 (3). Maximal oxygen uptake increased by 14%, to 2.47 l/min, whereas heart volume and vital capacity remained unchanged. Cardiac output and intrapulmonary gas exchange were also studied in 6 girls. Cardiac output in maximal exercise was 15.3 l/min; heart rate, 185 beats/min; stroke volume, 83 ml; and the arteriovenous oxygen diffence, 15.6 ml/100 ml. The stroke volume did not show the usually good correlation with heart volume. Normal values for V-E/V-O2, V-A/VO-2, V-A/Q, and PAO2-Pao2 were found both at rest and during exerice. The increase in maximal oxygen uptake after training was related to the increase in stroke volume. No increase was found in values for pulmonary gas exchange nor in the maximal arteriovenous oxygen difference. The results obtained suggest that a long period of previous intense physical training does not significantly influence the maximal aerobic power later in life when again sedentary. Moreover, the observed increase of 14% in VO2, max after 12 weeks of training may not be large enough to prove any advantageous effects when training is resumed.     

The intestinal T cell response to alpha-gliadin in adult celiac disease is focused on a single deamidated glutamine targeted by tissue transglutaminase

The great majority of patients that are intolerant of wheat gluten protein due to celiac disease (CD) are human histocompatibility leukocyte antigen (HLA)-DQ2(+), and the remaining few normally express HLA-DQ8. These two class II molecules are chiefly responsible for the presentation of gluten peptides to the gluten-specific T cells that are found only in the gut of CD patients but not of controls. Interestingly, tissue transglutaminase (tTG)-mediated deamidation of gliadin plays an important role in recognition of this food antigen by intestinal T cells. Here we have used recombinant antigens to demonstrate that the intestinal T cell response to alpha-gliadin in adult CD is focused on two immunodominant, DQ2-restricted peptides that overlap by a seven-residue fragment of gliadin. We show that tTG converts a glutamine residue within this fragment into glutamic acid and that this process is critical for T cell recognition. Gluten-specific T cell lines from 16 different adult patients all responded to one or both of these deamidated peptides, indicating that these epitopes are highly relevant to disease pathology. Binding studies showed that the deamidated peptides displayed an increased affinity for DQ2, a molecule known to preferentially bind peptides containing negatively charged residues. Interestingly, the modified glutamine is accommodated in different pockets of DQ2 for the different epitopes. These results suggest modifications of anchor residues that lead to an improved affinity for major histocompatibility complex (MHC), and altered conformation of the peptide-MHC complex may be a critical factor leading to T cell responses to gliadin and the oral intolerance of gluten found in CD.     

Serum levels of the low molecular weight form of insulin-like growth factor binding protein in healthy subjects and patients with growth hormone deficiency, acromegaly and anorexia nervosa

The low molecular weight form of insulin-like growth factor binding protein (35 kD IGFBP), determined in serum by radioimmunoassay during non-fasting conditions, was high at birth and declined with increasing age during childhood and adolescence (N = 149). Inverse correlation was found between chronological age and 35 kD IGFBP values (r = -0.61, P less than 0.001) during childhood and adolescence, but no age dependency was found in adult subjects aged 20-66 years (N = 73). The mean and 95% confidence limits of immunoreactive 35 kD IGFBP were 34 micrograms/l and 15-79 micrograms/l, respectively, in healthy adults (N = 73) in whom the blood samples were drawn after a one-night fast. The mean level of the 35 kD IGFBP in patients with acromegaly (19 micrograms/l, N = 23) was decreased by 50% in comparison with healthy adults, whereas a 2-fold elevation of the mean levels was found in both anorexia nervosa patients (70 micrograms/l, N = 13) and adult patients with GH deficiency (69 micrograms/l, N = 22). In patients with anorexia nervosa, the 35 kD IGFBP levels were inversely related to the body mass index (r = -0.65, P less than 0.02).