PubMed Health⌕ Search

Biomedical subjects

D Patakas

Publications and source records attributed to D Patakas.

At least 19 recordsLinked to original sources
PubMed2006

Visceral leishmaniasis infection in a patient with rheumatoid arthritis treated with etanercept.

Visceral leishmaniasis (VL) is a severe disease that can develop in immunocompromised patients. Antitumor necrosis factor-alpha (TNF-alpha) treatment of rheumatoid arthritis can result in clinical benefits, but with an increased risk of opportunistic infections. Leishmania infection in patients treated with TNF-alpha antagonists is extremely rare; for this reason, we report a patient with VL after etanercept treatment who had an unfavorable outcome.

Arthritis, Rheumatoid↗
PubMed2006

Diachronic study of pleural plaques in rural population with environmental exposure to asbestos.

BACKGROUND: The progress of pleural plaques in persons exposed to environmental asbestos in Almopia, Greece were studied prospectively. METHODS: During a 15-year period, 198 individuals, in whom pleural plaques had been observed during the period 1988-1990 were followed. Respiratory function was initially evaluated in 23. All were inhabitants of seven villages of Northern Greece, where rocks with high concentration in asbestos fibers were used for whitewashing until 1935. RESULTS: Out of this population, 126 survived and underwent chest X-ray in 2003 while respiratory function was retested in 18. New radiological findings were compared to previous ones using digital technology. Furthermore, the cause of death of the remaining 72 was recorded. Deterioration of X-ray findings was observed in all survivors. Not only did the surface area of previous plaques increase (8.66 +/- 12.6 cm2, mean value +/- SD) but new ones also appeared. Total lung capacity decreased from 95.6 +/- 14.8 in 1998 to 76.5 +/- 9.3% predicted in 2003. It was found that out of 72 deaths, 11 people died of malignant lung neoplasm, and 4 of mesothelioma. CONCLUSIONS: Radiological appearance of pleural plaques and respiratory function of people previously exposed to asbestos environmental pollution worsens over the years. Prevalence of mesothelioma was found to be higher than expected.

Adult↗
PubMed2006

Tuberculosis in patients receiving anti-TNF agents despite chemoprophylaxis.

SETTING: A major concern surrounding the use of tumor necrosis factor-alpha (TNF-alpha) inhibitors is their potential to increase the risk of opportunistic infections, particularly tuberculosis (TB). OBJECTIVE: To estimate the incidence of active TB in patients with rheumatic diseases receiving anti-TNF drug therapy and to evaluate the effectiveness of an antituberculosis chemoprophylaxis regimen. DESIGN: Retrospective study of the files of 613 patients with rheumatic diseases who had received anti-TNF agent (etanercept, infliximab and adalimumab) therapy from July 2000 to June 2004 at the Aristotle University of Thessaloniki, Greece. All patients had a tuberculin skin test (TST) and a postero-anterior chest radiograph (CXR) prior to anti-TNF therapy. When indicated (TST > or =10 mm and/or fibrotic lesions on CXR), treatment for latent TB was established (6 months isoniazid [INH] or 3 months INH and rifampicin [RMP]). Anti-TNF agent therapy was started again 2 months later. RESULTS: Of 45 patients who fulfilled the criteria for chemoprophylaxis, only 36 were treated correctly. Eleven patients developed active TB 2-35 months after the beginning of anti-TNF therapy. Six patients developed pulmonary and five extra-pulmonary TB. Eight of these had received infliximab and three adalimumab. CONCLUSION: The incidence of active TB in this study population was estimated at 449 cases per 100,00 population annually. Anti-tuberculosis chemoprophylaxis was only of partial preventive success in these patients.

Adalimumab↗
PubMed2004

Allergenic pollen records (15 years) and sensitization in patients with respiratory allergy in Thessaloniki, Greece.

BACKGROUND: Very limited allergenic pollen records exist in Greece so far; moreover, there is a lack of investigation on patient sensitization. The above data are necessary for respiratory allergy diagnosis and treatment worldwide. METHODOLOGY: Daily records and identification of 16 airborne pollen species were made using a Burkard trap (1987-2001). Skin sensitivity to 13 most common pollen extracts was investigated, in a sample of 1311 asthmatics with atopy, admitted to the Out-Patient Clinic for Asthma (1990-2001). Skin sensitivity to 55 allergens, including 13 pollen extracts, was detected by skin prick test. RESULTS: The following pollen concentrations were recorded: cypress (24.9% of the total), oak (20.8%), wall pellitory (13.6%), olive (9.1%), pine (8.9%), grasses (6.3%), plane (5.4%), hazel (3%), goosefoot (2.5%) and poplar (1.4%). The respective percentages of birch, ragweed, mugwort, willow, alder and elm were lower than 1%. The highest counts of airborne pollen grains were detected from March to June. Regarding patient sensitization, sensitivity was detected to: grasses in 530 patients (40.4%), olive 417 (31.8%), goosefoot 240 (18.3%), wall pellitory 201 (15.3%), mugwort 198 (15.1%), plantain 194 (14.6%), cypress 166 (12.7%), hazel 126 (9.6%), pine 122 (9.3%), poplar 111 (8.4%), plane 107 (8,2%), oak 99 (7.6%) and to birch 89 patients (6.8%). The sensitivity to pollen grains displays preponderance (57.9%) to males. CONCLUSIONS: For the first time in Thessaloniki, Greece, 15-year allergenic pollen records were conducted. Clinical observations confirm that the pollen mainly implicated in respiratory allergy symptoms are grasses, olive and wall pellitory.

Air Pollutants↗
PubMed2004

Allergenic fungi spore records (15 years) and sensitization in patients with respiratory allergy in Thessaloniki-Greece.

BACKGROUND: The prevalence of respiratory allergy to fungi spores (FS) is not precisely known but is estimated at 20-30% of atopic patients. There are no aerobiological records, necessary for respiratory allergy diagnosis and treatment, in Thessaloniki and generally in Greece. AIM: Creation of a database on FS circulation and investigation of skin sensitivity (SS) of asthmatics by using skin prick tests (SPT). MATERIAL AND METHODS: Daily records and identification of 15 airborne FS species were conducted, using a Burkard trap during 1987-2001. SS to 5 most common FS extracts was investigated, by using SPT in a total of 1311 asthmatics with atopy, submitted to the Out-Patient Clinic of Asthma (Pulmonary Dept, Aristotle Univ, Thessaloniki) in 1990-2001. RESULTS: The FS recorded in the 15-year period were as follows: Cladosporium spp. (72.2%), Alternaria spp. (9.8%), Ustilago spp. (8.1%), Ascospores (2.7%), Agrocybe spp. (1.5%), Helminthosporium spp. (1.4%), Leptosphaeria spp (1.2%), Agrogybe spp. (1.1%), whereas the species Botrytis, Stemphylium, Pleospora, Nigrospora, Epicoccum. Fusarium, Torula and Phoma presented concentrations <1%. The highest numbers of airborne FS were recorded during summer. Positive skin reaction to FS was observed in 421 (32%) patients of the 1311 asthmatics. Positive skin reaction to Altemaria species was observed in 177 patients (13.5%), in 98 (7.4%) to Cladosporium, 65 (5%) to Aspergillus, 45 (3.4%) to Fusarium and 36 (2.7%) to Rhizopus. FS sensitivity is much more frequent in younger men. CONCLUSIONS: For the first time in Thessaloniki-Greece, 15 allergenic FS species circulation has been recorded for the last 15 years. SS was more frequently detected for the species of Alternaria, Cladosporium and Aspergillus.

Air Microbiology↗
PubMed2003

15-year aeroallergen records. Their usefulness in Athens Olympics, 2004.

INTRODUCTION: About 5-25% of 16 000 athletes involved in preparation for the Athens 2004 Olympics may encounter respiratory allergy (asthma and rhinoconjunctivitis) triggered by exposure to aeroallergens (pollen and fungi spores). AIM: Provide information about circulating aeroallergens in three Olympic cities and ensure safety for the allergic athletes who will visit Greece from January to September 2004. METHODS: Aeroallergens were recorded using a Burkard volumetric trap. The most frequently implicated pollen (cypress, hazel, wall pellitory, plane, olive, grasses, goosefoot and mugwort) and fungi spores (Alternaria spp., Cladosporium spp.) are presented. These data derive from a 15-year database created by the Pulmonary Department, Thessaloniki, a 2-year database (University of Heraklion-Crete) and a 6-year database by the Pediatric Department, Athens. The above data and the current aeroallergen counts will be continuously announced by the mass media and Internet during the Athens 2004 Olympics. RESULTS: Are expressed as: (A) Presentation (Graphs, Tables) of the fluctuation of mean daily values of pollen grains or fungi spores/m3. (B) Presentation (Tables) of the start, peak and end time of aeroallergen circulation. Peak pollen concentrations were observed between March and May (athletes preparation time). During the 2004 Olympics (August-September) relatively high concentrations of goosefoot, mugwort, Alternaria and Cladosporium will be observed. Aeroallergens circulate in Athens 10-15 days earlier than in Thessaloniki and 10 days later than in Heraklion. CONCLUSIONS: The data presented in the study are expected to help allergic Olympic athletes achieve peak performance under prophylactic measures.

Allergens↗
PubMed2003

Serum total antioxidant status in severe exacerbation of asthma: correlation with the severity of the disease.

Oxidative processes, mediated by oxygen free radicals are recognized to contribute significantly to the inflammatory pathology of bronchial asthma. An imbalance between oxidants and antioxidants has also been proposed in this disease. This study examines the serum total antioxidant status (TAS) in asthmatic patients with severe exacerbation of their disease and the probable correlation with clinical or laboratory findings. The TAS was measured in 20 patients (10 men and 10 women, with a mean age of 41.95 +/- 20.75 years), using a colorimetric method. On the days of admission and discharge, the forced expiratory volume in 1 sec (FEV1), the partial arterial oxygen pressure (PaO2), and severity criteria were recorded and correlated with TAS at the same time. The TAS was also measured in 10 healthy subjects (8 men and 2 women, mean age of 39 +/- 9 years). A statistically significant decrease of TAS was observed on admission day compared to that on discharge day (0.98 +/- 0.08 vs. 1.12 +/- 0.17 mmol/L, p < 0.001, respectively, paired t-test) suggesting the presence of oxidative stress during an asthma attack. The TAS on admission was also statistically significantly decreased compared to that of normal subjects (0.98 +/- 0.08 vs. 1.19 +/- 0.09 mmo/L, p < 0.001, respectively, paired t-test). A statistically significant correlation was observed between FEV1 change and TAS change, from admission to discharge day (r = 0.58, p = 0.007, Pearson correlation). Finally, a statistically significant correlation was found between FEV1 change and TAS on discharge day (r = 0.65, p = 0.002). Decreased TAS was found during an asthma attack, probably as a consequence of increased oxidative stress. The TAS change was correlated with severity criteria, such as FEV1. Therefore, it seems that measurement of TAS could be a simple and useful tool in the evaluation of an asthma attack. The supplementary administration of antioxidants in future needs further clarification.

Adult↗
PubMed2002

Tumor necrosis factor-alpha serum levels, weight loss and tissue oxygenation in chronic obstructive pulmonary disease.

Weight loss has been recognized as a feature of advanced emphysema and a factor of poor prognosis, but its mechanisms remain obscure. Studies have demonstrated high serum concentrations of TNF-a (cachexin) in chronic obstructive pulmonary disease (COPD) patients with emphysema. Pink puffers (PP) COPD patients have worse tissue oxygenation when compared with blue bloaters (BB) COPD patients. Consequently, PP patients would become cachectic, whereas BB patients with better tissue oxygenation would not. The aim of this study is to test the hypothesis that malnutrition in emphysema is a cytokine-mediated marker of chronic progressive tissue hypoxia. Thirty male COPD patients, without clinical or laboratory evidence of infection and severe air way obstruction (FEV1 < 1.5 l) were allocated: 16 as pink puffers (PP) and 14 as blue bloaters (BB). Lung function measurements included FEV1, FVC, RV, TLC, DLCO and arterial blood gases on room air. TNF-a serum levels were measured by immunoenzymic method (ELISA). Tissue oxygenation was assessed from oxygen delivery (DO2), PvO2 and oxygen extraction ratio (O2ER) obtained after right heart catheterization with Swan Ganz catheter. PP patients demonstrated lower DLCO and higher TLC, FRC and PaO2 from BB. We found that oxygen delivery was better in our BB than in PP patients (CI 2.9 +/- 0.2 vs 2.5 +/- 0.4 l/min/m2--P < 0.01, DO2 16.1 +/- 2.1 vs 13.1 +/- 0.2 ml/min/kg--P < 0.001) and the same was found for tissue oxygenation (PvO2 34.6 +/- 2.9 vs 31.2 +/- 3.8 mmHg--P < 0.01, O2ER 0.27 +/- 0.02 vs 0.34 +/- 0.06%--P < 0.001). The TNF-a values were higher in PP (31.3 +/- 26 pg/ml vs 15.2 +/- 9.9 pg/ml--P < 0.05) and their percent fat-free mass (%FFM) was 49.6 +/- 11.5 vs 42 +/- 8%--P < 0.001. We found that COPD patients with lower DO2 had increased TNF-a levels; but the correlations between TNF-a serum levels and PvO2 or O2ER were not statistically significant. TNF-a levels were elevated in PP patients with tissue hypoxia and may be a factor contributing to the weight loss of these patients.

Cell Hypoxia↗
PubMed2001

A Phase II study of docetaxel and carboplatin in the treatment of non-small cell lung cancer.

We investigated the efficacy of docetaxel (D) in combination with carboplatin (C) in the treatment of non-small cell lung cancer (NSCLC) patients. Since 1996, 123 with inoperable NSCLC were enrolled in the study; 120 (108 males, 12 females; mean age 58.0+/-8.3 years) were evaluated. Of those, 46 patients had squamous carcinoma, 44 adenocarcinoma, 11 large cell carcinoma and 19 undifferentiated tumours. Eligibility criteria included, documented inoperable NSCLC, WHO performance status (PS) 0-1, age up to 70 years, and normal renal and hepatic function. A total of 622 cycles of chemotherapy (CHT) (median 7 (95% CI 6.2-7.47), courses per patient) were administered. Each cycle consisted of 100 mg/m(2) of docetaxel in a 2-h infusion with C at a dose of area under the curve (AUC) of 6 on day 1. This regimen was repeated every 28 days up to eight cycles. Of the patients, five (4%) achieved complete response, 49 (40%) partial response, 47 (39%) had stable disease and 19 (15%) had progressive disease. The median survival was 12 months for all patients, 12 for the four patients with stage IIb disease, 18 for the patients with stage IIIa disease, 20 for the 29 patients with stage IIIb disease, and 11 for the 65 stage IV patients. The median time to progression was 8 months (90 patients). Toxicity was, grade 3/4 neutropenia, 18 patients (15%); grade 3/4 anaemia, 6 patients (5%); and tolerable peripheral neuropathy, 16 patients (13.3%). Responders received radiotherapy (total dose, 50 Gy in 4 weeks) between the 6th and 8th cycle. Among responders with initial stage IIIb disease, 7 (5%) underwent surgical resection. Patients with early progression of the disease received the same dose of radiotherapy between 2nd and 3rd cycle. The study is ongoing, and six patients (5%) are still alive (after 3 years). Preliminary results indicate that the D/C combination is very active in the treatment of NSCLC with tolerable toxicity. It appears that this drug combination is also good as neoadjuvant therapy in inoperable NSCLC patients.

Adult↗
PubMed2001

Hering-Breuer reflex in normal adults and in patients with chronic obstructive pulmonary disease and interstitial fibrosis.

BACKGROUND: It has been suggested that the Hering-Breuer reflex (HBR) is unimportant in adults during normal tidal breathing and that it is elicited only if tidal volume is increased above a certain critical threshold. OBJECTIVE: The aim of this study was (1) to study the occurrence of the HBR in adults with normal pulmonary function and (2) to examine if changes in lung mechanics have any effect on the HBR. METHODS: We examined 11 adults with normal pulmonary function, 8 patients with chronic destructive pulmonary disease (COPD) and 3 with interstitial fibrosis (IF). All subjects were lightly sedated with fentanyl, intubated and ventilated with a Servo-900 ventilator. Inspiratory and expiratory flow (and after integration, volume) and mouth pressure were recorded from the endotracheal tube with a pneumotachograph and a pressure transducer. Pressure support ventilation was applied in all patients and functional residual capacity (FRC) was measured with the N(2) washout method. Mean (Te(mean)) and maximal expiratory time (Te(max)) were determined for each individual for 20 breaths. Following several breaths to establish a stable baseline the airway was occluded at end inspiration by a shutter. A positive HBR was interpreted as longer Te(occ) than Te(max) (Te(occ)/Te(max), %). Occlusion was maintained until negative airway pressure occurred and the occlusion time (Te(occ)) was measured. We attempted occlusions after the addition of 5 cm H2O positive end-expiratory pressure (PEEP) and subsequently with 10, 15 and 20 cm H(2)O PEEP. Te(occ) was measured of progressively larger lung volumes. To examine the HBR sensitivity in the three groups, we plotted the lung volumes of occlusion against the corresponding Te(occ)/Te(max). RESULTS: The ratio Te(occ)/Te(max) increased from 167.5 +/- 82.5 at normal FRC to 474 +/- 200.2 s (PEEP(20)). On the contrary, in patients with COPD, Te(occ)/Te(max) increased from 125.2 +/- 34 to 193.7 +/- 74.2 (p < 0.05). CONCLUSIONS: The HBR was positive in all subjects. COPD patients were found to be less sensitive to volume changes when compared with normal controls and with IF patients.

Aged↗
PubMed1999

Effects of chemical feedback on respiratory motor and ventilatory output during different modes of assisted mechanical ventilation.

The purpose of the study was to examine the effects of chemical feedback on respiratory motor and ventilatory output in conscious subjects ventilated on various modes of assisted mechanical ventilation. Seven subjects were connected to a ventilator and randomly ventilated on assist-volume control (AVC), pressure support (PS) or proportional assist ventilation (PAV). On each mode, the assist level was set to the highest comfortable level. Airway and oesophageal (Poes) pressures, tidal volume, respiratory frequency (fR) and end-tidal carbon dioxide tension (PET,CO2) were measured breath-by-breath. When the subjects were stable on each mode, the fraction of inspired carbon dioxide (FI,CO2) was increased stepwise, and changes in minute ventilation (V'E) and respiratory motor output, estimated by the pressure-time product of all the respiratory muscles per breath (PTPrm) and per minute (PTPminute), were observed. At zero FI,CO2, PTPminute/PET,CO2 did not differ between modes, while V'E/ PTPminute was significantly lower with PAV than that with PS and AVC. As a result V'E/PET,CO2 was significantly lower with PAV, preventing, unlike AVC and PS, a significant drop in PET,CO2. With PAV, independent of CO2, V'E/PTPminute remained constant, while it decreased significantly with increasing CO2 stimulus with PS and AVC. At high PET,CO2 respiratory effort was significantly lower with PAV than that with PS and AVC. In conclusion, the mode of mechanical ventilation modifies the effects of chemical feedback on respiratory motor and ventilatory output. At all carbon dioxide stimulus levels neuroventilatory coupling was better preserved with proportional assist ventilation than with pressure support and assist-volume control ventilation.

Adult↗
PubMed1999

Reversible platypnoea and orthodeoxia after surgical removal of an hydatid cyst from the liver.

A patient with a large hydatid cyst of the liver developed a positionally symptomatic right to left shunting across a patent foramen ovale with both platypnoea and orthodeoxia, despite normal pulmonary arterial pressures and normal pulmonary function tests. When the patient was in the supine position the calculated right to left shunt was 15.1% and 29.5% when seated. The shunt was attributed to the compression of the right atrium and ventricle by the cyst. Surgical evacuation of the cyst relieved the symptoms and the positionally induced shunting.

Cardiac Catheterization↗
PubMed1998

Comparison of the effects of salmeterol and ipratropium bromide on exercise performance and breathlessness in patients with stable chronic obstructive pulmonary disease.

To compare the effects of salmeterol, an adrenergic drug, and ipratropium bromide, an anticholinergic drug, on breathlessness and gas exchange during exercise in patients with chronic obstructive lung disease (COPD), we performed a progressive treadmill exercise test on 15 patients on 3 days (24 h apart), after inhalation placebo, ipratropium bromide (120 micrograms) or salmeterol (50 micrograms) in a randomized fashion. Dyspnoea during exercise was evaluated from the regression slope between Borg scale (BS) scores and distance walked each minute on the treadmill. The regression was expressed as the distance walked at BS score 5, the threshold load of dyspnoea (TLD) and breakpoint load of dyspnoea. During and after the exercise, oxygen saturation was monitored by pulse oxymeter and we measured the lower SaO2 during exercise and the recovery time of SaO2 after exercise. In comparison to placebo inhalation we found the same small but significant improvement in airflow limitation after salmeterol or ipratropium inhalation, also the distance walked on treadmill increased after bronchodilators. After bronchodilators the magnitude of oxyhaemoglobin desaturation with exercise was similar to that observed after placebo but the duration of the recovery from sustained SaO2 desaturation after exercise was shorter to the same extent as after ipratropium or salmeterol. Dyspnoeic sensation, when assessed by the TLD and by the distance walked at BS score 5, was decreased after salmeterol and after ipratropium bromide to a similar extent. We conclude that the salmeterol, when given in conventional doses, produces significant improvement in the airway obstruction in the recovery of postexercise HbO2 desaturation and in dyspnoeic sensation in patients with COPD, effects which were similar to those observed after inhalation of the anticholinergic agent ipratropium bromide.

Adrenergic beta-Agonists↗
PubMed1997

Respiratory response to CO2 during pressure-support ventilation in conscious normal humans.

The respiratory response to CO2 during pressure-support ventilation (PSV) was studied in 16 conscious normal humans. The subjects breathed through a mouthpiece connected to a ventilator in PSV mode, with pressure set to the highest comfortable level for each subject (10.1 +/- 0.6 cm H2O, mean +/- SE). Compared with breathing spontaneously through the ventilator (CPAP mode with zero positive end-expiratory pressure), with PSV, tidal volume (VT) increased significantly (1.16 +/- 0.1 versus 0.85 +/- 0.04 L), whereas breathing frequency (f) remained stable (16.0 +/- 0.9 versus 15.6 +/- 1.1 breaths/min). As a result, the subjects hyperventilated, decreasing significantly end-tidal PCO2 (PETCO2, 23.5 +/- 1.2 versus 35.5 +/- 1.1 mm Hg). Fraction of inspired CO2 (FICO2) was then increased in steps, and changes in respiratory motor output were quantitated from changes in f, VT, ventilation (VI), peak inspiratory flow (Vpeak), and muscle pressure (Pmus). Pmus was calculated by the equation of motion, based on respiratory system mechanics, which were measured previously by airway occlusion at end-inspiration, VT, VI, and Pmus increased significantly with increasing PETCO2, and the response was detectable even below eupneic levels; f remained relatively stable over a wide range of PETCO2 (23 to 45 mm Hg) and increase significantly only when PETCO2 approached 50 mm Hg. These results indicate that in conscious normal humans during PSV, CO2 responsiveness extends well into hypocapnia and is expressed principally as an increase in intensity of respiratory motor output with little change in respiratory rate.

Adult↗
PubMed1995

Effects of breathing patterns on mechanically ventilated patients with chronic obstructive pulmonary disease and dynamic hyperinflation.

OBJECTIVE: To examine the circulatory and respiratory effects of breathing pattern in patients with chronic obstructive pulmonary disease (COPD) and dynamic hyperinflation (DH) during controlled mechanical ventilation. DESIGN: Prospective, controlled, randomized, non-blinded study. SETTING: Respiratory intensive care unit of a university hospital. PATIENTS: Nine patients with acute respiratory failure and DH due to acute exacerbations of COPD. INTERVENTIONS: Keeping tidal volume and total breath duration (TTOT) constant, patients were ventilated at six different values of expiratory time (TE). TE changes were randomly induced by alterations of constant inspiratory flow (VI) and/or end-inspiratory pause (EIP). Patients were studied at three levels of VI(0.93 +/- 0.08, 0.72 +/- 0.06 and 0.55 +/- 0.04 l/s, mean +/- SE), with and without EIP (10% of TTOT). MEASUREMENTS AND RESULTS: Lung volumes, airflows, airways pressures, oxygenation indices and dead space were measured. Alveolar pressure and airway resistance (Rmin), as well as the additional resistance (delta R) due to viscoelastic pressure dissipation and time-constant inequalities, were estimated by rapid airway occlusion during inflation. In seven out of nine patients, right-heart catheterization was performed and hemodynamic parameters were obtained at each value of TE. A significant decrease of intrinsic positive end-expiratory pressure (PEEPi), end-inspiratory static and mean (mPaw) airway pressures, end-expiratory lung volume above passive FRC (Vtrap), delta R and venous admixture and a significant increase of peak airway pressure, Rmin, stroke volume index and mixed venous PO2 (PvO2) were observed when VI increased. At each VI, the addition of EIP significantly decreased iso-volume expiratory flows and PvO2 and increased Vtrap and mPaw. CONCLUSIONS: We conclude that in mechanically ventilated patients with COPD, the pattern of lung inflation and TE alteration have a significant impact on respiratory system mechanics, gas exchange and hemodynamics. Addition of EIP in patients with COPD may be detrimental.

Acute Disease↗
PubMed1995

Ventilatory post-stimulus potentiation in patients with brain damage.

In normal humans when a brief hypoxic ventilatory stimulus is terminated abruptly by breathing 100% O2, ventilation during hyperoxia gradually declines to baseline prehypoxic levels without an undershoot. This has been interpreted as evidence of decay of short-term potentiation (STP), a mechanism located in the brainstem and not dependent upon higher center inputs. STP decay may be important in preventing periodic breathing by damping ventilatory responses to cyclic stimuli. Patients with brain damage commonly have periodic breathing that may be caused partly by impairment of STP activation. To test this 12 tracheostomized patients with severe brain damage (Glasgow score 9.9 +/- 0.6) were studied. Breathing stability was estimated by at least 6 h of capnography and from these records apnea index (AI, episodes/hour) and cyclic changes of end-tidal CO2 (c-PETCO2, cycles/hour) were derived. STP activation was examined by brief exposure to hypoxia (45 s, end-tidal O2 = 50 mm Hg) followed by hyperoxia. Forty-four hypoxic-hyperoxic runs were analyzed and compared with 19 normoxic-hyperoxic trials. At the end of the hypoxia ventilation (VI) increased 39.5 +/- 5.8% and PETCO2 decreased 2.7 +/- 0.6 mm Hg to 91.5 +/- 2.2% of baseline value. When hypoxia was terminated abruptly by hyperoxia VI dropped immediately to 63.2 +/- 7.2% of baseline, remaining for 35 s significantly lower than the corresponding values acquired during hyperoxia after normoxia. After hypoxia, apneas occurred in 19 of 44 hyperoxic runs. There was a negative relationship between nadir hyperoxic ventilation after hypoxia and both AI and c-PETCO2.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Effect of hypoxic sensitivity on decay of respiratory short-term potentiation.

In normal conscious humans, when a brief hypoxic ventilatory stimulus is followed immediately by breathing 100% O2, ventilation during hyperoxia gradually declines to baseline prehypoxic levels without an undershoot. During the decline, ventilation is greater than baseline in the absence of hypoxia and hypercapnia. This has been interpreted as evidence of decay of short-term potentiation (STP) or afterdischarge. It is not known whether the intensity of the stimulus that activates STP influences the time course of its decay. Therefore we studied STP decay in nine normal adults after administration of placebo (P) and almitrine (A) in a single-blind manner on 2 separate days. On each day, three runs consisting of 45 s of isocapnic hypoxia (end-tidal PO2 = 55 mm Hg) followed by 2 min of hyperoxia were conducted while ventilation (VI) was measured breath by breath. Baseline VT did not differ between A and P, but at the end of hypoxia, VI with A was 169 +/- 14% (SE) of baseline while VI with P was 132 +/- 7% of baseline (p < 0.05). Immediately after hyperoxia was instituted, VI fell abruptly, the fall being 36% of baseline for A and 15% for P. This probably represented the withdrawal of peripheral chemoreceptor input. Thereafter, VI declined slowly toward baseline, and the time course of this decline did not differ between P and A. Our results indicate that within the limits we studied, the increase of the intensity of the discharge of the peripheral chemoreceptors during hypoxia does not influence STP decay.

Adult↗