Spontaneous minute ventilation is a predictor of extubation failure in extremely-low-birth-weight infants.

OBJECTIVE: To validate the percentage of time spent below a target value of spontaneous expiratory minute ventilation (< 125 ml/min per kg) during a 2-h period of continuous positive airway pressure (CPAP) via an endotracheal tube (ETT) as a predictor of failed extubation in preterm infants. METHODS: Forty-one infants intubated for at least 24 h, with birth weight between 500 and 1000 g, who were clinically stable and at ventilator setting compatible with an extubation attempt, were studied during a 2-h period of ETT CPAP. Dynamic lung compliance and total lung resistance were measured during a period of quiet breathing, while tidal volume (Vt), respiratory rate and the corresponding spontaneous expiratory minute ventilation values were calculated for the complete recording period of 2 h using a customized computer program. The time each patient spent below the target spontaneous expiratory minute ventilation value was reported as a percentage of the total recorded time (% spontaneous expiratory minute ventilation < 125 ml/min per kg). Extubation failure was defined as the need for reintubation within 72 h. RESULTS: Eleven out of 41 babies (26.8%) experienced failure of extubation (failure group) while 30 infants (73.2%) were successfully extubated (success group). There were no significant differences in dynamic lung compliance and lung resistance between the two groups, but the mean values of respiratory rate and spontaneous expiratory minute ventilation were significantly lower in the failure group than in the success group: 43 (37-56) breaths/min and 240 (160-353) ml/min per kg vs. 53 (28-67) breaths/min and 309 (223-434) ml/min per kg, respectively (p = 0.0129 and p = 0.0039). Moreover, the babies in whom extubation failed spent a longer time below the target value of spontaneous expiratory minute ventilation when compared with successfully extubated babies (p < 0.0001). Percentage of time spent with spontaneous expiratory minute ventilation < 125 ml/min per kg had a larger area than transcutaneous (Tc)PCO2, TcPO2 and pulse oxymetry saturation (SpO2) under the receiver operator characteristic curves. CONCLUSION: The measurement of spontaneous expiratory minute ventilation prior to extubation could be useful in identifying those babies who are not ready for spontaneous ventilation.     

Surgical treatment of complex tibial plateau fractures by closed reduction and external fixation. A review of 32 consecutive cases operated

Abstract Complex tibial plateau fractures are a challenge in trauma surgery. In these fractures it is necessary to anatomically reduce the articular part of the fracture and to obtain stable fixation. The aim of this study is to review the results of a surgical technique consisting of fluoroscopic closed reduction and combined percutaneous internal and external fixation. Thirty-two complex tibial plateau fractures in 32 patients were included. Twenty-one fractures were closed, 4 were open Gustilo grade I, 3 were Gustilo grade II and 4 were Gustilo grade III. The mean age was 37.8 years (range 21–64 years). Surgery was performed with patients in transcalcaneal traction and the knee flexed at 30° was used. Through a 1-cm incision centred over the tibial metaphysis of the tibia, a 3.2-mm hole was drilled in the antero-medial tibial aspect. The tibial plateau fracture fragments were elevated using either 1 or 2 curved Kirschner wires under fluoroscopy to control the reduction. Then the fragments were fixed with 2 cannulated AO screws inserted through small incisions into the medial aspect of the tibial plateau. Knee rehabilitation started postoperatively. Weight bearing started after 8–12 weeks depending upon the radiographic appearance. All external fixators were removed in outpatient facilities. All patients were clinically and radiographically evaluated at a mean follow-up of 48 months (range 38–57 months). Clinical results were evaluated according to the Knee Society clinical score. Average healing time was 24 weeks (range 18–29 weeks). In 1 patient a non-union occurred. This patient was treated with open reduction and plate fixation. In 2 patients a varus knee deformity occurred and a surgical correction was performed. There were no surgical complications. Mean knee range of motion was 105° (range 75–125°) and mean Knee Society clinical score was 89. Twenty-five results were scored as excellent, 4 good, 2 fair and 1 poor. Using this technique there is limited soft tissue damage and virtually no periosteum damage to the fracture fragments. However anatomical reconstruction of the joint can be obtained. Furthermore knee rehabilitation can be started immediately after surgery. We think that these factors were responsible for the optimal clinical long-term results.     

Chest wall kinematics and respiratory muscle action in ankylosing spondylitis patients.

No direct measurements of the pressures produced by the ribcage muscles, the diaphragm and the abdominal muscles during hyperventilation have been reported in patients with ankylosing spondylitis. Based on recent evidence indicating that abdominal muscles are important contributors to stimulation of ventilation, it was hypothesised that, in ankylosing spondylitis patients with limited ribcage expansion, a respiratory centre strategy to help the diaphragm function may involve coordinated action of this muscle with abdominal muscles. In order to validate this hypothesis, the chest wall response to a hypercapnic/hyperoxic rebreathing test was assessed in six ankylosing spondylitis patients and seven controls by combined analysis of: 1) chest wall kinematics, using optoelectronic plethysmography, this system is accurate in partitioning chest wall expansion into the contributions of the ribcage and the abdomen; and 2) respiratory muscle pressures, oesophageal, gastric and transdiaphragmatic (Pdi); the pressure/volume relaxation characteristics of both the ribcage and the abdomen allowed assessment of the peak pressure of both inspiratory and expiratory ribcage muscles, and of the abdominal muscles. During rebreathing, chest wall expansion increased to a similar extent in patients to that in controls; however, the abdominal component increased more and the ribcage component less in patients. Peak inspiratory ribcage, but not abdominal, muscle pressure was significantly lower in patients than in controls. End-inspiratory Pdi increased similarly in both groups, whereas inspiratory swings in Pdi increased significantly only in patients. No pressure or volume signals correlated with disease severity. The diaphragm and abdominal muscles help to expand the chest wall in ankylosing spondylitis patients, regardless of the severity of their disease. This finding supports the starting hypothesis that a coordinated response of respiratory muscle activity optimises the efficiency of the thoracoabdominal compartment in conditions of limited ribcage expansion.     

The magnetic resonance of small hepatocarcinoma. A comparison with echography, computed tomography, digital angiography and computed tomography with lipiodol]

Diagnostic techniques as a whole and periodic ultrasonography (US) in particular frequently allows tumors < 3 cm (small hepatocellular carcinomas) to be detected in patients suffering from liver cirrhosis. Multifocal diseases are a major limitation to surgery. Recently, MR imaging has shown its capabilities in the diagnosis of small hepatocellular carcinomas. In our study the diagnostic value of MR imaging was compared with that of US, of pre- and post-contrast CT, of digital angiography and of CT after lipiodol injection (Lipiodol CT). The morphologic and signal intensity MR features of small hepatocellular carcinomas were investigated. Fifteen cirrhotic patients with 31 nodules of hepatocellular carcinoma < 3 cm were examined. All patients were studied with US, MR imaging, angiography and Lipiodol CT; 12/15 patients underwent CT. Histologic confirmation was obtained in 12 nodules (2 at surgery and 10 by means of percutaneous biopsy); in the extant 19 cases the diagnosis was made by combining US, CT, MR, angiographic and lipiodol-CT findings; in 9 tumors < 1 cm Lipiodol retention one month after angiography was considered as diagnostic. MR imaging detected 21/31 nodules (63%), US 22/31 (66.6%), CT 12/24 (50%), angiography 24/31 (74%), lipiodol CT 29/31 (92.5%). Mc Nemar test showed no difference in sensitivity between MR imaging and CT, MR and angiography, MR and US, lipiodol CT and angiography; however, the differences between the detection rates of MR imaging and Lipiodol CT and CT and lipiodol CT and US were statistically significant (p < 0.05). The difference in sensitivity between the detection rates of lipiodol CT and US was just above the threshold value which is usually considered significant (p = 0.065). One false positive was observed on US and none with MR, CT, angiography and lipiodol CT. On Se T1-weighted images 18 nodules were hyperintense, 2 isointense and 2 hypointense; on proton-density images 14 nodules were hyperintense, 7 isointense and none hypointense. On SE T2-weighted images 18 nodules were hyperintense, 3 isointense and none hypointense. A pseudocapsule was seen in 10/17 nodules (58%), especially on T1-weighted images. Accuracy and limitations of each technique and morphologic and signal intensity MR findings of small hepatocellular carcinoma are discussed. We believe that US is still the best diagnostic technique for the screening of hepatocellular carcinomas in cirrhotic livers.(ABSTRACT TRUNCATED AT 400 WORDS)     

Low ceiling respiratory depression by ciramadol

Ciramadol, an agonist-antagonist analgesic of lesser milligram potency than morphine, given intravenously at 30 mg/70 kg produced respiratory depression equivalent to that observed with morphine 10 mg/70 kg. Respiratory depression was measured in terms of drug induced displacement of the carbon dioxide response curve of healthy volunteers. In contrast to the progressive respiratory depression by each 10 mg/70 kg increment of morphine, further doses of ciramadol up to 90 mg/70 kg failed to increase respiratory depression. The ceiling of respiratory depression by ciramadol was half the ceiling previously demonstrated for nalbuphine and dezocine. Ceiling respiratory depression may be a general characteristic of agonist-antagonist type analgesics in contrast to pure agonist analgesics.     

Novel Method for Processing Respiratory Specimens for Detection of Mycobacteria by Using C18-Carboxypropylbetaine: Blinded Study

A novel method for processing respiratory specimens to improve culture and acid-fast staining of mycobacteria is introduced. This new method utilized N,N-dimethyl-N-(n-octadecyl)-N-(3-carboxypropyl)ammonium inner salt (Chemical Abstract Service no. 78195-27-4), also known as C₁₈-carboxypropylbetaine (CB-18). In a blinded, five-center study, CB-18-based processing was compared to the standard method combining NALC and NaOH (NALC/NaOH). A total of 573 respiratory specimens were tested. Individual specimens were split approximately equally; the host institutions processed half of each specimen by the NALC/NaOH method, while the other half was processed with CB-18 at Quest Diagnostics—Baltimore. A total of 106 specimens were culture positive for acid-fast bacilli (AFB). Replacement of the primary decontamination agent with CB-18 caused changes in all diagnostic parameters. Aggregate culture sensitivity improved by approximately 43% (P < 0.01), and smear sensitivity improved by approximately 58% (P < 0.01). The sensitivity of smear relative to that of M. tuberculosis isolates exceeded 93% (P < 0.01) when specimens were processed with CB-18. The average times to a positive result were reduced by 7.3 days in liquid culture (P < 0.01) and 5.3 days on solid media (P < 0.05); however, the CB-18 method had a 20.8% contamination rate in liquid culture versus a rate of approximately 7.5% with NALC/NaOH processing. There were also unusual reductions in liquid culture sensitivity and smear specificity among CB-18-processed specimens. The characteristics of the latter parameters suggested that refinement of the CB-18 processing method should allow further improvements in culture sensitivity. This study showed that the CB-18 method has the potential to improve both smear and culture detection for these important human pathogens.     

Evaluation of a reformulated CHROMagar Candida

CHROMagar Candida is a differential culture medium for the isolation and presumptive identification of clinically important yeasts. Recently the medium was reformulated by Becton Dickinson. This study was designed to evaluate the performance of the new formula of CHROMagar against the original CHROMagar Candida for recovery, growth, and colony color with stock cultures and with direct plating of clinical specimens. A total of 90 stock yeast isolates representing nine yeast species, including Candida dubliniensis, as well as 522 clinical specimens were included in this study. No major differences were noted in growth rate or colony size between the two media for most of the species. However, all 10 Candida albicans isolates evaluated consistently gave a lighter shade of green on the new CHROMagar formulation. In contrast, all 26 C. dubliniensis isolates gave the same typical dark green color on both media. A total of 173 of the 522 clinical specimens were positive for yeast, with eight yeast species recovered. The recovery rates for each species were equivalent on both media, with no consistent species-associated differences in colony size or color. Although both media were comparable in performance, the lighter green colonies of C. albicans isolates on the new CHROMagar made it easier to differentiate between C. albicans and C. dubliniensis isolates. In conclusion, the newly formulated Becton Dickinson CHROMagar Candida medium is as equally suited as a differential medium for the presumptive identification of yeast species and for the detection of multiple yeast species in clinical specimens as the original CHROMagar Candida medium.     

Walking modality affects respiratory muscle action and contribution to respiratory effort

We hypothesized that walking at increased speed or increasing gradient might have different effects on chest wall kinematics and respiratory muscle power components, and contribute differently to respiratory effort sensation. We measured the volumes of chest wall compartments by optoelectronic plethysmography, esophageal, gastric and transdiaphragmatic (P _di) pressures, and the sensation of the respiratory effort by a Borg scale in five normal subjects walking both at ascending gradient with constant speed (AG) and at ascending speed with constant gradient (AS). Chest wall kinematics, evaluated by displacement of chest wall compartments, did not show any significant difference between AS and AG. Muscle power, calculated as the product of mean flow and mean pressure, increased similarly, but its partitioning into pressure and velocity of shortening differed in the two modes. A greater increase in the pressure developed by the abdominal muscles (P _abm) (4.06-fold), and in the velocity of shortening of both rib cage inspiratory muscles (v _rcm,i) (2.01-fold) and the diaphragm (v _di) (1.90-fold) was associated with a lower increase in the pressure developed by the rib cage inspiratory muscles (P _rcm,i) (1.24-fold) and P _di (0.99-fold) with AG. Instead, with AS, a lower increase in P _abm (2.12-fold), v _rcm,i (1.66-fold) and v _di (1.54-fold) was associated with a greater increase in P _rcm,i (1.56-fold) and P _di (1.97-fold). A combination of P _abm and v _di during AG (Wald ²=23.19, P<0.0000), with the addition of P _rcm,i during AS (Wald ²=29.46, P<0.0000), was the best predictor of Borg score. In conclusion, the general strategy adopted by respiratory centers during different walking modes does not differ in terms of ventilation, chest wall kinematics, and respiratory muscle power production, whereas it does in terms of partitioning of power into pressure and velocity of shortening, and respiratory muscle contribution to respiratory effort sensation. Combinations of different patterns of flow and pressure generation made the respiratory effort sensation similar during AS and AG modes.