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Biomedical subjects

J Jordanoglou

Publications and source records attributed to J Jordanoglou.

At least 19 recordsLinked to original sources
PubMed2004

Unevenness of ventilation assessed by the expired CO(2) gas volume versus V(T) curve in asthmatic patients.

Recently, we have shown that the expired CO2 gas volume versus tidal volume (VCO2-VT) curve is a useful tool for assessing unevenness of ventilation because it allows the separation of tidal volume into three functional compartments: (a) the CO2-free expired air (V0), (b) the transitional volume (Vtr), (c) the alveolar volume (VA) and the measurement of alveolar FCO2 during resting breathing in normal subjects and patients with COPD. In this paper, we have investigated whether changes pertaining to unevenness of ventilation taking place immediately after the administration of methacholine can be assessed using the VCO2-VT curve in asthmatic patients. The VCO2-VT curve was obtained during tidal breathing from 16 stable asthmatic patients who underwent a methacholine challenge test. It has been found that the Vtr, and hence Bohr's dead space (VD,Bohr = V0 + Vtr), over tidal volume ratios were significantly increased immediately after the methacholine administration, whilst the V0 over tidal volume ratio was not affected. The change of the above ratios was not related to the percentage decrease of FEV1.0 following methacholine administration.

Administration, Inhalation↗
PubMed2003

Tidal expiratory flow limitation, dyspnoea and exercise capacity in patients with bilateral bronchiectasis.

In this study the authors investigated whether expiratory flow limitation (FL) is present during tidal breathing in patients with bilateral bronchiectasis (BB) and whether it is related to the severity of chronic dyspnoea (Medical Research Council (MRC) dyspnoea scale), exercise capacity (maximal mechanical power output (WRmax)) and severity of the disease, as assessed by high-resolution computed tomography (HRCT) scoring. Lung function, MRC dyspnoea, HRCT score, WRmax and FL were assessed in 23 stable caucasian patients (six males) aged 56 +/- 17 yrs. FL was assessed at rest both in seated and supine positions. To detect FL, the negative expiratory pressure (NEP) technique was used. The degree of FL was rated using a five-point FL score. WRmax was measured using a cyclo-ergometer. According to the NEP technique, five patients were FL during resting breathing when supine but not seated, four were FL both seated and supine, and 14 were NFL both seated and supine. Furthermore, it was shown that: 1) in stable BB patients FL during resting breathing is common, especially in the supine position; 2) the degree of MRC dyspnoea is closely related to the five-point FL score; 3) WRmax (% pred) is more closely correlated with the MRC dyspnoea score than with the five-point FL score; and 4) HRCT score is closely related to forced expiratory volume in one second % pred but not five-point FL score. In conclusion, flow limitation is common at rest in sitting and supine positions in patients with bilateral bronchiectasis. Flow limitation and reduced exercise capacity are both associated with more severe dyspnoea. Finally, high-resolution computed tomography scoring correlates best with forced expiratory volume in one second.

Adult↗
PubMed2001

Combined expression of p53, Bcl-2, and p21WAF-1 proteins in lung cancer and premalignant lesions: association with clinical characteristics.

We examined p53, p21WAF-1, and Bcl-2 protein expression in malignant and nonmalignant bronchial specimens obtained during bronchoscopy from 60 lung cancer patients. Twenty-six (43.3%), 36 (60%), and 20 (33.3%) of the tumors were p53, p21WAF-1, and Bcl-2 positive, respectively. High-level p53 and Bcl-2 expression characterized advanced preneoplastic lesions, while hyperplasias, squamous metaplasias, and mild dysplasias exhibited low levels of expression. There was no difference between early and advanced preneoplastic lesions in the level of p21WAF-1, expression. A history of heavy smoking was associated with p21WAF-1, expression in preneoplastic lesions (p = 0.022) and tumors (p = 0.032). p53(-)/p21WAF-1(++)/bcl-2(-) was the only significant independent predictor of lower clinical stage (OR: 0.88, p = 0.038). In univariate analysis, survival of NSCLC patients was affected by disease stage (p <0.001) and tumor histology (p = 0.018). While single-protein expression was not associated with prognosis, the combined immunophenotype p53(-)/p21WAF-1(++)/bcl-2(-) predicted longer survival (p = 0.03). In multivariate analysis, only the TNM stage was found to be a prognostic factor for NSCLC. We conclude that p53 and Bcl-2 alterations may happen early in bronchial carcinogenesis and that absence of these alterations in combination with p21WAF-1, overexpression may be associated with a less aggressive tumor behavior.

Aged↗
PubMed2001

A multicenter randomized clinical trial comparing paclitaxel-cisplatin-etoposide versus cisplatin-etoposide as first-line treatment in patients with small-cell lung cancer.

BACKGROUND: Previous phase I-II studies have shown that the combination of paclitaxel-cisplatin-etoposide (TEP) is very active and well tolerated in patients with small-cell lung cancer (SCLC). In order to compare the TEP combination to cisplatin etoposide (EP) regimen as front-line treatment in patients with SCLC, we conducted a randomised multicenter study. PATIENTS AND METHODS: One hundred thirty-three chemotherapy-naïve patients with histologically proven limited or extensive stage SCLC were randomised to receive either paclitaxel 175 mg/m2 i.v. three-hour infusion on day 1 and cisplatin 80 mg/m2 i.v. on day 2 and etoposide 80 mg/m2 i.v. on days 2-4 with G-CSF support (5 mcg/kg s.c. days 5-15) or cisplatin 80 mg/m2 i.v. on day 1 and etoposide 120 mg/m2 i.v. on days 1-3 in cycles every twenty-eight days. RESULTS: Due to excessive toxicity and mortality observed in the TEP arm, an early interim analysis was performed and the study was closed. Sixty-two patients received two hundred sixty-one cycles of TEP and seventy-one patients three hundred twenty-three cycles of EP The two patient groups were well balanced for age, sex, performance status, stage of disease and the presence of abnormal LDH at diagnosis. In an intention-to-treat overall analysis both regimens were equally active with a complete and partial response rate of 50% (95% confidence interval (CI): 37.5%-62.4%) for TEP and 48% (95%) CI: 36.2%-59.5%) for EP (P = 0.8). The median time to disease progression was 11 months for TEP and 9 months for EP (P = 0.02). The duration of response, one-year survival and overall survival were similar in the two arms. Similarly, in an intention-to-treat subgroup analysis of patients with limited or extensive stage disease, there was no difference in the activity between the two regimens except of a longer median time to disease progression in the extensive stage in favour of the TEP regimen, eight versus six months (P = 0.04). However, there were eight toxic deaths in the TEP arm versus none in the EP arm (P = 0.001). Moreover, the TEP regimen was associated with more severe toxicity than the EP regimen in terms of grade 4 neutropenia (P = 0.04), grade 3-4 thrombocytopenia (P = 0.02), febrile neutropenia (P = 0.08), grade 3-4 diarrhea (P = 0.01), grade 3-4 asthenia (P = 0.05) and grade 3 neurotoxicity (P = 0.06). CONCLUSIONS: In this early terminated study, the TEP regimen was significantly more toxic than the EP regimen. The TEP regimen is associated with significant toxicity and mortality, and should not be used outside of a protocol setting. For future investigations, dose and schedule modifications are necessary to reduce toxicity.

Adult↗
PubMed2001

Noninvasive measurement of mean alveolar carbon dioxide tension and Bohr's dead space during tidal breathing.

The lack of methodology for measuring the alveolar carbon dioxide tension (PA,CO2) has forced investigators to make several assumptions, such as that PA,CO2 is equal to end-tidal (PET,CO2) and arterial CO2 tension (Pa,CO2). The present study measured the mean PA,CO2 and Bohr's dead space ratio (Bohr's dead space/tidal volume (VD,Bohr/VT)) during tidal breathing. The method used is a new, simple and noninvasive technique, based on the analysis of the expired CO2 volume per breath (VCO2) versus the exhaled VT. This curve was analysed in 21 normal, healthy subjects and 35 chronic obstructive pulmonary disease (COPD) patients breathing tidally through a mouthpiece apparatus in the sitting position. It is shown that: 1) PA,CO2 is similar to Pa,CO2 in normal subjects, whilst it is significantly lower than Pa,CO2 in COPD patients; 2) PA,CO2 is significantly higher than PET,CO2 in all subjects, especially in COPD patients; 3) VD,Bohr/VT is increased in COPD patients as compared to normal subjects; and 4) VD,Bohr/VT is lower than the "physiological" dead space ratio (VD,phys/VT) in COPD patients. It is concluded that the expired carbon dioxide versus tidal volume curve is a useful tool for research and clinical work, because it permits the noninvasive and accurate measurement of Bohr's dead space and mean alveolar carbon dioxide tension accurately during spontaneous breathing.

Adult↗
PubMed2000

Eosinophils are a feature of upper and lower airway pathology in non-atopic asthma, irrespective of the presence of rhinitis.

BACKGROUND: Asthma and rhinitis often co-exist and there are data to suggest that they may be two ends of the same disease spectrum. Immunohistochemical studies have shown that eosinophilia in the airways is a feature of rhinitic patients without asthma. OBJECTIVE: The aim of our study was to examine whether cellular infiltration exists in the nasal mucosa of asthmatics even in the absence of symptoms and signs of rhinitis. METHODS: Nasal mucosa biopsies were taken from 27 non-atopic subjects and comprised nine asthmatic rhinitic patients (AR), eight asthmatic non-rhinitic patients (ANR) and 10 healthy control subjects (N). Bronchial mucosa biopsies were also taken simultaneously from some of the patients (n = 10) to determine whether there was an association between cellular infiltration in the nose and the lungs. The alkaline phosphatase-anti-alkaline phosphatase (APAAP) method was used on 6 microm thick cryostat sections using monoclonal antibodies against T cells (CD4, CD8), eosinophils (EG2) and mast cells (mast cell tryptase). Slides were counted blind and results expressed as cells per field. RESULTS: The results showed that eosinophil counts were higher in both asthma groups compared with control nasal biopsies (median values AR 8.3, ANR 9.2, N 2.1 cells per field, P < 0.01). Furthermore, there was a significant correlation between eosinophil cell counts in the nose and the airways (r = 0.851 P < 0.001). No differences in eosinophil numbers were detected between the two groups of asthmatics. Also, no differences were noted for any other cell type (i.e. CD4, CD8, tryptase) among the three study groups. CONCLUSIONS: These results show that eosinophil infiltration was present in the nasal mucosa of asthmatic patients even in the absence of rhinitis, and add further support to the hypothesis that asthma and rhinitis are clinical expressions of the same disease entity.

Adult↗
PubMed2000

Left ventricular function in patients with obstructive sleep apnoea syndrome before and after treatment with nasal continuous positive airway pressure.

BACKGROUND: Previous studies have yielded disparate results regarding the effect of obstructive sleep apnoea (OSA) syndrome on left ventricular (LV) function. OBJECTIVES: In order to clarify this, we performed a prospective study investigating OSA patients with no history of systemic hypertension, coronary artery disease, myocardial, pericardial or valvular problems, asthma or chronic obstructive pulmonary disease before and after treatment with nasal continuous positive airway pressure (nCPAP). METHODS: Fifteen patients (3 women, 12 men) with an apnoea/hypopnoea index >15 (mean +/- SD = 52 +/- 21) were studied with complete polysomnography, ambulatory blood pressure monitoring, M-mode two-dimensional echocardiography and pulsed Doppler echocardiography in two phases, i.e. before and after 12-14 weeks of nCPAP therapy. We measured systolic and diastolic blood pressure (BP) separately in the daytime and night-time, isovolumic relaxation time (IVRT), the ratio of peak early filling velocity (E) to peak late velocity (A) diastolic transmitral flow (E/A), posterior wall thickness (PWT) and septal thickness (IVST). The shortening fraction (SF) was also calculated. Eleven overweight non-apnoeic normal subjects matched for age were used as the control group. RESULTS: Our results showed that the patient group exhibited, before treatment, LV diastolic, but not systolic, dysfunction compared with the normal group (IVRT = 94.3 +/- 11.6 ms, p < 0.05; E/A = 0.94 +/- 0.26, p < 0.02; SF = 39.9 +/- 4.1%, not significant (NS); IVST = 9.9 +/- 1.2 mm, NS; PWT = 8.3 +/- 1.2 mm, NS). Moreover, the patient group developed diastolic hypertension both in the daytime and night-time (BP/diastolic/daytime = 93.3 +/- 9.2 mm Hg, BP/diastolic/night-time = 90.3 +/- 10.7 mm Hg). After 12-14 weeks of nCPAP treatment (no change in body mass index), significant improvement in LV diastolic function and a drop in blood pressure were noticed (IVRT = 85.6 +/- 8.8 ms, p < 0.05; E/A = 1.07 +/- 0.3, p < 0.05; BP/diastolic/daytime = 86.3 +/- 5.5 mm Hg, p < 0.02; BP/diastolic/night-time = 83.9 +/- 8. 6 mm Hg, p < 0.05) in our patient group. CONCLUSIONS: We conclude that repetitive apnoeas/hypopnoeas are very important factors in the development of both LV diastolic dysfunction and diastolic systemic hypertension in patients with OSA syndrome. Treatment with nCPAP leads to significant improvement in both ventricular function and systemic hypertension.

Administration, Intranasal↗
PubMed1998

Expression of mdm-2 protein in neoplastic, preneoplastic, and normal bronchial mucosa specimens: comparative study with p53 expression.

Loss of function of the p53 tumor supressor gene is involved in nearly all human cancer. Recently a cellular oncogene product, mdm2, has been shown to bind to p53 and eliminate its ability to function as a transcription factor. mdm2 and p53 immunohistochemical protein expression was studied in tumor tissues, preneoplastic lesions, and normal bronchial mucosa. The specimens were obtained during diagnostic bronchoscopy from 53 patients with lung cancer. In the tumor specimens, p53 nuclear staining was detected in 26 (49%) cases, mdm2 in 11 (20.7%), and simultaneous expression of both proteins in 6 (11.3%) cases. Thirty-five sections with preneoplastic lesions were found in 21 patients. p53 nuclear staining was found in 11 of 35 and mdm2 in 6 of 35 sections. In normal cells, mdm2 positive staining was found in 18 and p53 in 12 specimens. Simultaneous p53 and mdm2 expression was found in 4 specimens. Our results indicate that p53 expression is more frequent than mdm2 expression in lung cancer tissues. Alterations in these proteins are early events and may represent alternative pathways in carcinogenesis.

Bronchi↗
PubMed1998

Optimal duration of chemotherapy in small cell lung cancer: a randomized study of 4 versus 6 cycles of cisplatin-etoposide.

With the purpose of investigating whether the 6-course standard dose treatment of etoposide-platinum (EP) in small cell lung cancer could be reduced to 4 courses without compromising patient's survival, 70 patients were randomized to receive either 4 or 6 cycles of etoposide 120 mg/m2 i.v. days 1-3 and cisplatin 80 mg/m2 day 1. With the intention of comparing these two durations as primary treatment policies, patients were randomized on admission and not after the fourth course. From the 69 evaluable patients 34 received EPx4 cycles and 35 EPx6 cycles. Objective response for EPx4 was achieved by 21 patients (62%, 95% CI 44%-78%) compared to 24 patients (69%, 95% CI 51%-83%) of the EPx6 group. Median times to progression were 6 mo (4-19) and 7 mo (4-40) respectively (P=0.06) in the two groups. Median survivals were 8.5 mo (4-28.5) and 9.5 mo (4-51) (p=0.04) respectively. No differences in the survival of limited-disease patients were shown with 10.5 mo (6-28.5) and 12 mo (8-51) respectively, in the two groups. Patients with extensive disease had a trend favoring prolonged chemotherapy with a median survival of 9 mo (5-16) versus 6.5 mo (4-16.5) for those in the EPx4 group (p=0.09). Toxicity was not significantly more severe in the EPx6 group. In conclusion, patients achieving complete response within 4 cycles may not need continued chemotherapy, but patients with extensive disease may benefit from 2 more cycles.

Adult↗
PubMed1998

Phrenic nerve dysfunction after cardiac operations: electrophysiologic evaluation of risk factors.

BACKGROUND AND STUDY OBJECTIVE: Phrenic nerve injury may occur after cardiac surgery; however, its cause has not been extensively investigated with electrophysiology. The purpose of this study was to determine by electrophysiologic means the importance of various possible risk factors in the development of phrenic nerve dysfunction after cardiac surgical operations. DESIGN: A prospective study was conducted. SETTING: A tertiary teaching hospital provided the background for the study. PATIENTS: Sixty-three cardiac surgery patients on whom surgical operations were performed by the same surgical team constituted the study group. Mean (+/-SD) age and ejection fraction were 63+/-5 years and 50+/-10%, respectively. INTERVENTIONS: Measurement of phrenic nerve conduction latency time after transcutaneous stimulation preoperatively and at 24 h and 7 and 30 days postoperatively. RESULTS: Thirteen patients had abnormal phrenic nerve function postsurgery, 12 on the left side and one bilaterally. Logistic regression analysis revealed that among the potential risk factors investigated, use of ice slush for myocardial preservation was the only independent risk factor related to phrenic nerve dysfunction (p=0.01), carrying an 8-fold higher incidence for this complication. In contrast, age, ejection fraction of the left ventricle, operative/bypass/aortic cross-clamp time, left internal mammary artery use, and diabetes mellitus were not found to be associated with phrenic neuropathy. The postoperative outcome of patients who received ice slush compared with that of those who had cold saline solution did not differ in terms of early morbidity and mortality. CONCLUSION: Among the risk factors investigated, only the use of ice slush was significantly associated with postoperative phrenic nerve dysfunction. Therefore, ice should be avoided in cardiac surgery, since it does not seem to provide additional myocardial protection.

Aged↗
PubMed1998

Adenosine deaminase activity and lysozyme levels in bronchoalveolar lavage fluid in patients with pulmonary tuberculosis.

SETTING: The estimations of adenosine deaminase (ADA) activity and lysozyme (LYS) levels in pleural fluid have been proved useful tools in the diagnosis of tuberculous pleural effusions. Little is known about their usefulness when estimated in bronchoalveolar lavage fluid (BALF). OBJECTIVE: To evaluate whether both ADA activity and LYS levels in BALF could be employed in the diagnosis of pulmonary tuberculosis, and especially in active but acid fast bacilli (AFB) smear negative cases. DESIGN: ADA activity and LYS levels were determined in BALF and serum obtained on the same day in 28 patients with tuberculosis, 21 with interstitial lung diseases, 14 with lung cancer and 13 with infectious diseases. RESULTS: Patients with pulmonary tuberculosis had significantly higher ADA activity in BALF than patients with non-tuberculous lung diseases (P < 0.001). High BALF ADA activity in pulmonary tuberculosis patients suggests increased local production. In contrast, in this group of patients BALF LYS levels were not significantly higher than in the other groups of patients, but were in the group with interstitial lung diseases. CONCLUSION: BALF ADA activity seems to be a useful tool in the differentiation of tuberculosis from other lung diseases. Its estimation can be restricted to the detection of cases with AFB negative smears.

Adenosine Deaminase↗
PubMed1997

Dependence of forced vital capacity manoeuvre on time course of preceding inspiration in patients with restrictive lung disease.

In normal subjects and patients with airway obstruction, flows during a forced vital capacity (FVC) manoeuvre are higher after a fast inspiration without an end-inspiratory pause (manoeuvre 1) as compared to a slow inspiration with an end-expiratory pause of approximately 5 s (manoeuvre 2). In this study, we investigated the influence of these manoeuvres on maximal expiratory volume-time and flow-volume curves in patients with restrictive lung disease. Eleven patients with restrictive lung disease were studied. Their average (+/-SD) lung function test results were: FVC=55+/-12% predicted value, forced expiratory volume in one second (FEV1) 52+/-20% pred, FEV1/FVC 85+/-6%, total lung capacity 55+/-8% pred, and carbon monoxide transfer factor 47+/-18% pred. The patients performed the two FVC manoeuvres in random order. We compared the ensuing spirograms and maximal expiratory flow-volume curves from which peak expiratory flow, FEV1, FEV1/FVC, maximal mid-expiratory flow, and maximal flows were computed. All spirometric indices were significantly higher with manoeuvre 1 than 2. Maximal expiratory flows at the same lung volume were also significantly higher with manoeuvre 1 than 2, in all patients. Routine spirometric indices, obtained during a forced vital capacity manoeuvre depend on the time course of the preceding inspiration in patients with restrictive lung disease. Therefore, the forced vital capacity manoeuvre should be standardized if used in clinical, epidemiological and research studies.

Adult↗
PubMed1996

Tumour necrosis factor, interleukin-1 and adenosine deaminase in tuberculous pleural effusion.

Tumour necrosis factor (TNF) and interleukin-1 (IL-1) are powerful mediators with a key role in inflammation. This study was undertaken to study the presence of TNF and IL-1 in tuberculous effusion where there is marked inflammation and where examination of the pleural fluid may give information about the local inflammatory reaction. Adenosine deaminase activity (ADA, a marker of TB pleurisy) was also tested. Tumour necrosis factor, IL-1 and ADA levels were measured in the pleural fluid and serum of 97 patients; 33 with tuberculous effusion, 33 with malignant effusion, and 31 patients with benign non-tuberculous effusion. Pleural fluid TNF and ADA levels were higher in tuberculous (TB) patients than in patients with benign disorders or cancer (P < 0.01). Serum TNF levels were also higher in TB patients than other benign (P < 0.01) or malignant (P < 0.05) effusions. There was a positive correlation between serum and pleural fluid values (r = 0.998-0.999, P < 0.001) although pleural fluid concentration was higher (P < 0.001), possibly suggesting local production in the pleural cavity. Pleural fluid IL-1 levels were not raised in any patient group but there was a positive correlation between TNF and IL-1. In addition, a positive correlation was found between TNF and ADA levels, probably indicating some common production mechanism. Furthermore, ADA sensitivity in the diagnosis of tuberculous effusion was augmented by the combined use of TNF and ADA. The use of both these markers may prove useful in the differential diagnosis of TBC pleurisy.

Adenosine Deaminase↗
PubMed1996

Recurrent respiratory papillomatosis with malignant transformation in a young adult.

The term 'papilloma' was first used by Mackenzie 100 years ago, who claimed that this was the most benign tumour of the larynx. Today papillomas are considered to be caused by the Human Papilloma Virus group (H.P.V.). The majority of patients suffering from this disease which is also referred to as 'recurrent respiratory papillomatosis' require multiple surgical operations for tumour removal. Malignant transformation of papillomas, which is a rare condition, is considered to occur mainly to irradiated patients. The following report describes the case of a male patient, with a history of vocal cord papillomas since his first year of age, who developed bronchial and pulmonary spread of the disease. He died at the age of 26 years because of squamous cell carcinoma which was related to the malignant transformation of the pulmonary papillomas.

Adult↗
PubMed1995

Molecular and immunohistochemical study of class I growth factor receptors in squamous cell lung carcinomas.

The class I growth factor receptor family includes epidermal growth factor receptor, i.e. c-erbB-1, c-erbB-2 and c-erbB-3 molecules. These receptors have a significant sequence homology and play an important role in cell growth and differentiation. To further investigate their implication in squamous cell lung carcinomas (SqCLCs), we studied the protein expression by immunohistochemistry and examined for possible gene amplification by a novel semi-quantitative differential polymerase chain reaction (DPCR) technique. Expression of c-erbB-1, c-erbB-2 and c-erbB-3 was present in 65%, 28% and 10% respectively, of 40 SqCLCs cases. Seven of the 11 cases that expressed c-erbB-2, as well as all 4 c-erbB-3 expressing cases, also stained with the anti-c-erbB-1 mAb. Expression of c-erbB-1, but not of c-erbB-2 or c-erbB-3, correlated with the grade of tumor differentiation (100%, 64% and 36% positive cases of well, moderately and poorly differentiated cases respectively, p < 0.003). In addition, c-erbB-1 expression correlated with the presence of regional lymph node metastases within the moderately differentiated group. The c-erbB-1 gene was amplified in 11/40 (28%) cases, all of which overexpressed c-erbB-1 protein, while c-erbB-2 gene amplification was detected in only one case. There was no c-erbB-3 gene amplification in any of the 40 SqCLCs cases. These findings suggest that c-erbB-1, c-erbB-2 and c-erbB-3 receptors do not have a common role and are of different physiological importance, at least at the stage of clinically overt tumor in human SqCLCs.

Base Sequence↗
PubMed1995

Measurement of effective alveolar carbon dioxide tension during spontaneous breathing in normal subjects and patients with chronic airways obstruction.

BACKGROUND: The measurement of effective alveolar carbon dioxide tension (PA-CO2eff) is still a matter of debate. It has, however, become common practice to use arterial instead of alveolar CO2 tension for computing alveolar oxygen tension (PAO2) and physiological dead space, not only in normal subjects but also in patients. The purpose of this study was to estimate alveolar CO2 tension during spontaneous breathing with a new bedside technique which is simple and non-invasive, and to compare these values with arterial CO2 tension measured in normal subjects and patients with chronic airways obstruction. METHODS: The subjects breathed quietly through the equipment assembly (mouthpiece, monitoring ring, Fleisch transducer head) connected to a pneumotachograph and a fast response infrared CO2 analyser. The method is a computerised calculation of the volume weighted effective alveolar CO2 tension obtained from the simultaneously recorded expiratory flow and CO2 concentration versus time curves. An arterial blood sample was taken to measure PaCO2 for comparison during the study. RESULTS: The results showed a mean difference (PACO2eff-PaCO2) of -0.205 kPa in 20 normal subjects and -0.460 kPa in 46 patients. The 95% confidence interval of the bias was -0.029 to -0.379 kPa in normal subjects and -0.213 to -0.707 kPa in patients. The limits of agreement between PACO2eff and PaCO2 were 0.526 to -0.935 in normal subjects and 1.170 to -2.088 in patients. CONCLUSIONS: The volume weighted effective alveolar PCO2 in normal subjects and patients with chronic airways obstruction is lower than the arterial PCO2 and is recommended as a better estimate in the classical equations for estimating dead space and intrapulmonary shunt.

Adult↗