Directional Atherectomy With Antirestenotic Therapy Versus PTA/Supera Stenting for Popliteal Artery Lesions: A Propensity-Matched Analysis.

PURPOSE: This study examines the use and impact of directional atherectomy with antirestenotic therapy (DAART) versus angioplasty plus Supera stent implantation on the outcomes during endovascular treatment of popliteal lesions in clinical practice. METHODS: Overall 143 consecutive patients (mean age 75.0±12.2 years, 72% male), with isolated atherosclerotic disease of the popliteal artery who underwent endovascular treatment using DAART therapy or percutaneous transluminal angioplasty (PTA)/Supera stenting of the popliteal artery between January 2016 and December 2021 were identified from a retrospectively database. Patient and plaque characteristics were collected. A propensity-score matched, case-control analysis was conducted to balance covariates between the group of patients who underwent DAART and the one treated by PTA/Supera stenting. RESULTS: A total of 51 patients (35.7%) showed severe claudication and 92 (64.3%) critical limb ischemia. There was a trend toward longer treated lesions (90.4±81 vs 72.5±5.3 mm, p=0.089) and more chronic total occlusions (60.5% vs 46.8%, p=0.058) in the PTA/Supera stenting group, although not reaching statistically significance. Moderate-to-severe calcification was present in most lesions treated (75.8% of DAART group, 80.2% of PTA/Supera stenting group, and 78.3% of total cohort). Among the 53 case-matched pairs of patients treated with DAART or PTA/Supera stenting, there were no significant differences in short-term outcomes, including rate of technical success (96.2% vs 98.1%, p=0.232), procedural success (88.7% vs 90.1%, p=0.251), distal embolization (1.9% vs 1.9%, p=0.178), dissection (5.7% vs 1.9%, p=0.268), perforation (3.8% vs 5.6%, p=0.163), hospital discharge (1.2±0.1 vs 1.0±0.1, p=0.325), 30 day minor (28.3% vs 32.1%, p=0.264) or major amputation rates (7.5% vs 3.8%, p=0.107), and 30 day mortality (1.9% vs 1.9%, p=0.173). At 1 year, there was no difference in primary patency (73.6% vs 77.4%, p=0.233), primary assisted patency (81.3% vs 84.9%, p=0.167), secondary patency (86.8% vs 92.5%, p=0.094), ipsilateral minor (35.8% vs 39.6%, p=0.472) or major amputation (9.4% vs 7.5%, p=0.186), ankle brachial index improvement (0.32±0.12 vs 0.37±0.37, p=0.401), or mortality (5.7% vs 5.7%, p=0.121) rate between patients who underwent DAART or PTA/Supera stenting for popliteal lesions. CONCLUSION: Twelve-month results following DAART technique or PTA/Supera stenting of atherosclerotic lesions of the popliteal artery are not different, regardless of patient and plaque characteristics. CLINICAL IMPACT: The DAART technique for the treatment of popliteal artery atherosclerotic disease is presented as a "leave nothing behind" strategy with on-year clinical outcomes similar to ATP/Supera stenting.

Rye B chromosomes influence the dynamics of histone H3 methylation during microgametogenesis.

We have studied the trimethylation dynamics of lysines 4 and 27 of histone H3 in rye with and without B chromosomes (Bs) in root tip mitosis, meiosis, and pollen grain mitosis by immunostaining. In root meristems, H3K4me3 immunolabeling was homogeneous along the chromosome arms of the normal complement (As), with the exception of the pericentromeric and subtelomeric regions which were unlabeled. On the contrary, a signal was observed on the long arm of the B chromosome, in the region where most of the B-specific repeats are located. H3K27me3 immunosignals were observed on the subtelomeric heterochromatic region of the As and the Bs and some interstitial bands of the As. Thus, the terminal region of the Bs showed both signals, whereas the subtelomeric region of the As showed H3K27me3 immunosignals only. During meiosis and first pollen grain mitosis, the immunosignals were observed distributed as in the root tip mitosis in plants with or without Bs. However, we observed remarkable changes in the immunolabeling patterns during the second pollen grain mitosis between 0B and +B plants. In 0B plants, H3K4me3 immunosignals were similarly distributed in the vegetative and generative nuclei. In B-carrying plants, the vegetative nucleus showed a lighter signal than the generative one. In 0B plants, all nuclei of the microgametophyte showed H3K27me3 immunosignals. In B-carrying plants, the generative nucleus and, correspondingly, the second metaphase, anaphase, and sperm nuclei did not show any signal. When the Bs were lost as micronuclei, they did not show any H3K4me3 or H3K27me3 signal. Most remarkably, Bs are able to change the pattern of H3 methylation on K4 and K27 during the second pollen mitosis, resulting in differently labeled sperm nuclei in 0 and +B plants.

Influence of atmospheric pressure on the incidence of spontaneous pneumothorax.

BACKGROUND: This study analyses the relationship between the incidence of idiopathic spontaneous pneumothorax (ISP) and atmospheric pressure (AP). METHODS: A total of 288 cases of ISP were included, 229 men and 59 women. The AP of the day of diagnosis, of the 3 prior days and the monthly average was registered. The association between the incidence of ISP and AP was analyzed by calculating standardized incidence ratio (SIR) and Poisson regression. RESULTS: The AP on the day of admission (mean±standard deviation) (1,017.9±7 hectopascals [hPa]) was higher than the monthly average AP (1,016.9±4.1 hPa) (P=.005). There was a monthly distribution pattern of ISP with the highest incidence in the months of January, February and September and the lowest in April. When AP was less than 1,014 hPa, there were fewer cases registered than what would statistically have been expected (58/72 cases). In contrast, when the pressure was higher than 1,019 hPa, the registered cases were more than expected (109/82 cases) (SIR=1.25; 95% CI: 1.04 to 1.51). The risk of ISP increased 1.15 times (95% CI: 1.05 to 1.25, P=.001) for each hPa of AP, regardless of sex, age and monthly average AP. A dose-response relationship was observed, with progressive increases in risk (IRR=1.06 when the AP was 1,014-1016 hPa; 1.17 hPa when the AP was 1,016-1,019 hPa and 1.69 when AP was superior to 1,019 hPa) (P for trend=.089). CONCLUSION: The AP is a risk factor for the onset of idiopathic spontaneous pneumothorax.

[Effect of vitamin D deficiency on hypocalcaemia after total thyroidectomy due to benign goitre]. / Efecto de la deficiencia de vitamina D sobre la hipocalcemia tras tiroidectomía total por bocio benigno.

INTRODUCTION: The purpose of this study was to analyse the relationship between preoperative serum levels of vitamin D and postoperative hypocalcaemia after total thyroidectomy. MATERIAL AND METHODS: A prospective observational study was conducted on 113 patients treated by total thyroidectomy due to benign disease. Preoperative vitamin D serum levels and postoperative albumin-corrected calcium and parathormone (PTH) levels were determined. Sensitivity, specificity, positive predictive value and negative predictive value of vitamin D and PTH levels, respectively, in the diagnosis of postoperative hypocalcaemia were calculated. RESULTS: Hypocalcaemia was diagnosed in 44 (38.9%) patients. Vitamin D levels were significantly higher in the group of patients with normal postoperative calcium (median: 25.4pg/mL; range: 4-60), compared to those who developed hypocalcaemia (median: 16.4pg/mL; range: 6.3-46.9) (P=.001). Postoperative hypocalcaemia was more frequent in patients with vitamin D < 30ng/mL (39/78) (50%), than among those with normal levels (5/35) (14.2%) (P=.001). Sensitivity, specificity, positive predictive value and negative predictive value were 88% and 68%, 43% and 82%, 50% and 71%, and 85% and 80% for vitamin D and PTH, respectively. Vitamin D and PTH showed independent prognostic values on the risk of hypocalcaemia. The OR associated with vitamin D < 30ng/mL was 4.25 (95% CI: 1.31-13.78) (P=.016), and the OR of PTH<13pg/mL was 15.4 (95% CI: 4.83-49.1) (P<.001). CONCLUSION: Vitamin D deficiency is a risk factor of hypocalcaemia after total thyroidectomy for benign goitre. The vitamin D level provides independent prognostic information, which is complementary to that given by PTH.

Diverticulitis with abscess formation: Outcomes of non-operative management and nomogram for predicting emergency surgery: The Diplicab Study Collaborative Group.

BACKGROUND: To assess short- and long-term outcomes from non-surgical management of diverticulitis with abscess formation and to develop a nomogram to predict emergency surgery. METHODS: This nationwide retrospective cohort study was performed in 29 Spanish referral centers, including patients with a first episode of a diverticular abscess (modified Hinchey Ib-II) from 2015 to 2019. Emergency surgery, complications, and recurrent episodes were analyzed. Regression analysis was used to assess risk factors, and a nomogram for emergency surgery was designed. RESULTS: Overall, 1,395 patients were included (1,078 Hinchey Ib and 317 Hinchey II). Most (1,184, 84.9%) patients were treated with antibiotics without percutaneous drainage, and 194 (13.90%) patients required emergency surgery during admission. Percutaneous drainage (208 patients) was associated with a lower risk of emergency surgery in patients with abscesses of ≥5 cm (19.9% vs 29.3%, P = .035; odds ratio 0.59 [0.37-0.96]). The multivariate analysis showed that immunosuppression treatment, C-reactive protein (odds ratio: 1.003; 1.001-1.005), free pneumoperitoneum (odds ratio: 3.01; 2.04-4.44), Hinchey II (odds ratio: 2.15; 1.42-3.26), abscess size 3 to 4.9 cm (odds ratio: 1.87; 1.06-3.29), abscess size ≥5 cm (odds ratio: 3.62; 2.08-6.32), and use of morphine (odds ratio: 3.68; 2.29-5.92) were associated with emergency surgery. A nomogram was developed with an area under the receiver operating characteristic curve of 0.81 (95% confidence interval: 0.77-0.85). CONCLUSION: Percutaneous drainage must be considered in abscesses ≥5 cm to reduce emergency surgery rates; however, there are insufficient data to recommend it in smaller abscesses. The use of the nomogram could help the surgeon develop a targeted approach.

Discrimination between silicone oil droplets and protein aggregates in biopharmaceuticals: a novel multiparametric image filter for sub-visible particles in microflow imaging analysis.

PURPOSE: Accurate monitoring of the sub-visible particle load in protein biopharmaceuticals is increasingly important to drug development. Manufacturers are expected to characterize and control sub-visible protein particles in their products due to their potential immunogenicity. Light obscuration, the most commonly used analytical tool to count microscopic particles, does not allow discrimination between potentially harmful protein aggregates and harmless pharmaceutical components, e.g. silicone oil, commonly present in drug products. Microscopic image analysis in flow-microscopy techniques allows not only counting, but also classification of sub-visible particles based on morphology. We present a novel approach to define software filters for analysis of particle morphology in flow-microscopic images enhancing the capabilities of flow-microscopy. METHODS: Image morphology analysis was applied to analyze flow-microscopy data from experimental test sets of protein aggregates and silicone oil suspensions. RESULTS: A combination of four image morphology parameters was found to provide a reliable basis for automatic distinction between silicone oil droplets and protein aggregates in protein biopharmaceuticals resulting in low misclassification errors. CONCLUSIONS: A novel, custom-made software filter for discrimination between proteinaceous particles and silicone oil droplets in flow-microscopy imaging analysis was successfully developed.

[Relationship between parathormone concentration during surgery and the post-operative outcome of primary hyperparathyroidism]. / Relación entre concentración intraoperatoria de parathormona y evolución postoperatoria del hiperparatiroidismo primario.

INTRODUCTION: The relationship between the intra-operative concentration of parathyroid hormone (IOPTH) and the long-term outcome of patients intervened due to primary hyperparathyroidism (PHPT). PATIENTS AND METHODS: A prospective observational study was performed with 120 patients. Three determinations were made of PTH in blood: baseline, when the diseases gland was located, and 10 minutes after its extirpation. The calcium, PTH and vitamin D (25-OH-D3) levels were measured during follow up. RESULTS: A decrease in IOPTH > 50% was observed in 96 (80%) patients, and the post-extirpation value returned to the normal range (Group I), in 18 (15%) a decrease of > 50% but the final value remained higher than normal (Group II) and in 6 (5%) the decrease was<50% (Group III). Persistent PHPT was detected during follow up in 6 patients (5%): one in Group I (1%), 3 (16.7%) in II and 2 (33.3%) in group III (P<.001). The risk of persistent PHPT was higher in Group II (odds ratio: 19; 95% CI: 1.85-194) and in Group III (odds ratio: 47; 95% CI: 3.53-639). There were no cases of recurrent PHPT. A normal calcium with an increased PTH was detected in 20 patients of Group I (20.8%), 11 (61.1%) in II and 3 (50%) in III (P<.001). These patients had a lower concentration of post-operative vitamin D (17 ng/ml, range: 24; compared to 28 ng/ml, range: 21) (P=.008) and higher frequency of hypovitaminosis D (70.6% compared to 26.2%) (P>.001). CONCLUSION: The risk of persistent PHPT is higher when the IOPTH decreases more than 50% but still remains high.

Subunit movements in single membrane-bound H+-ATP synthases from chloroplasts during ATP synthesis.

Subunit movements within the H(+)-ATP synthase from chloroplasts (CF(0)F(1)) are investigated during ATP synthesis. The gamma-subunit (gammaCys-322) is covalently labeled with a fluorescence donor (ATTO532). A fluorescence acceptor (adenosine 5'-(beta,gamma-imino)triphosphate (AMPPNP)-ATTO665) is noncovalently bound to a noncatalytic site at one alpha-subunit. The labeled CF(0)F(1) is integrated into liposomes, and a transmembrane pH difference is generated by an acid base transition. Single-pair fluorescence resonance energy transfer is measured in freely diffusing proteoliposomes with a confocal two-channel microscope. The fluorescence time traces reveal a repetitive three-step rotation of the gamma-subunit relative to the alpha-subunit during ATP synthesis. Some traces show splitting into sublevels with fluctuations between the sublevels. During catalysis the central stalk interacts, with equal probability, with each alphabeta-pair. Without catalysis the central stalk interacts with only one specific alphabeta-pair, and no stepping between FRET levels is observed. Two inactive states of the enzyme are identified: one in the presence of AMPPNP and one in the presence of ADP.

Proton-powered subunit rotation in single membrane-bound F0F1-ATP synthase.

Synthesis of ATP from ADP and phosphate, catalyzed by F(0)F(1)-ATP synthases, is the most abundant physiological reaction in almost any cell. F(0)F(1)-ATP synthases are membrane-bound enzymes that use the energy derived from an electrochemical proton gradient for ATP formation. We incorporated double-labeled F(0)F(1)-ATP synthases from Escherichia coli into liposomes and measured single-molecule fluorescence resonance energy transfer (FRET) during ATP synthesis and hydrolysis. The gamma subunit rotates stepwise during proton transport-powered ATP synthesis, showing three distinct distances to the b subunits in repeating sequences. The average durations of these steps correspond to catalytic turnover times upon ATP synthesis as well as ATP hydrolysis. The direction of rotation during ATP synthesis is opposite to that of ATP hydrolysis.

Subunit movements in membrane-integrated EF0F1 during ATP synthesis detected by single-molecule spectroscopy.

The H+ -ATPsynthase from E. coli was isolated and labelled at the gamma- or epsilon-subunit with tetramethylrhodamine, and at the b-subunits with bisCy5. The double labelled enzymes were incorporated into liposomes. They showed ATP hydrolysis activity, and, after energization of the membrane by DeltapH and Deltavarphi, also ATP synthesis activity was observed. Fluorescence resonance energy transfer (FRET) was used to investigate the movements of either the gamma-subunit or the epsilon-subunit relative to the b-subunits in single membrane-integrated enzymes. The results show that during catalysis, the gamma-epsilon complex rotates stepwise relative to the b-subunit. The direction of rotation during ATP synthesis is opposite to that during ATP hydrolysis. The stepwise motion is characterized by dwell times (docking time of the gamma-epsilon complex to one alphabeta pair) up to several hundred ms, followed by a rapid movement of the gamma- and epsilon-subunit to the next alphabeta pair within 0.2 ms. The same FRET levels (i.e., the same gamma-b and epsilon-b distances) are observed during proton transport-coupled ATP hydrolysis and ATP synthesis, indicating that the reaction proceeds via the same intermediates in both directions. Under non-catalytic conditions, i.e., in the absence of ATP or without energization also, three FRET levels are found, however, the distances differ from those under catalytic conditions. We conclude that this reflects a movement of the epsilon-subunit during active/inactive transition.

Pharmacokinetic/pharmacodynamic modeling of benazepril and benazeprilat after administration of intravenous and oral doses of benazepril in healthy horses.

Pharmacokinetic and pharmacodynamic (PK/PD) properties of the angiotensin-converting enzyme inhibitor (ACEI) benazeprilat have not been evaluated in horses. This study was designed to establish PK profiles for benazepril and benazeprilat after intravenous (IV) and oral (PO) administration of benazepril using a PK/PD model. This study also aims to determine the effects of benazeprilat on serum angiotensin converting enzyme (ACE), selecting the most appropriate dose that suppresses ACE activity. Six healthy horses in a crossover design received IV benazepril at 0.50mg/kg and PO at doses 0 (placebo), 0.25, 0.50 and 1.00mg/kg. Blood pressures (BP) were measured and blood samples were obtained at different times in order to measure serum drug concentrations and serum ACE activity, using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and spectrophotometry, respectively. Systemic bioavailability of benazeprilat after PO benazepril was 3-4%. Maximum ACE inhibitions from baseline were 99.63% (IV benazepril), 6.77% (placebo) and 78.91%, 85.74% and 89.51% (for the three PO benazepril doses). Significant differences in BP were not found. Although oral availability was low, benazeprilat 1.00mg/kg, reached sufficient serum concentrations to induce long lasting serum ACE inhibitions (between 88 and 50%) for the first 48h. Additional research on benazepril administration in equine patients is indicated.

Modulation of acute transient exercise-induced hypertension after oral administration of four angiotensin-converting enzyme inhibitors in normotensive horses.

Changes in blood pressure (BP) during acute hypertension in response to angiotensin-converting enzyme inhibitors (ACEIs) have not been investigated in normotensive horses. In this study, six healthy horses were subjected to five trials, consisting in a treadmill exercise workload of 8 m/s for 1 min, 2 h after oral administration (PO) of placebo (0 mg/kg), enalapril (2.0 mg/kg), quinapril (1.0 mg/kg), ramipril (0.2 mg/kg) or benazepril (0.5 mg/kg). Serum angiotensin converting enzyme (ACE) activity was measured and systolic (SBP) and diastolic (DBP) blood pressures were recorded at rest (R), 2 h after placebo or ACEI administration (pre-E) and within the first 20 s after exercise (post-E). Mean maximum serum ACE inhibition 2 h after PO administration was 4.8% (placebo), 39.4% (enalapril), 46.4% (quinapril), 55.0% (ramipril) and 71.68% (benazepril). There were no significant differences in serum ACE inhibition between enalapril and quinapril. SBP and DBP at times R and pre-E were not different in any of the five trials. In response to exercise, SBP increased by 67.6% (placebo), 52.7% (enalapril), 43.1% (quinapril), 26.6% (ramipril) and 4.2% (benazepril). In response to exercise, DBP increased by 20.6, 13.2, 11.7, 16.6 and 3.7% after placebo, enalapril, quinapril, ramipril and benazepril administration, respectively. Serum ACE activity changed during exercise, but statistical significance was not achieved. In conclusion, administration of PO benazepril at a dose of 0.5 mg/kg modulated physiological hypertension induced by exercise in horses that were otherwise normotensive.

In vitro assembly of mosaic hepatitis B virus capsid-like particles (CLPs): rescue into CLPs of assembly-deficient core protein fusions and FRET-suited CLPs.

Hepatitis B virus core protein self-assembles into icosahedral, highly immunogenic capsid-like particles (CLPs) that can serve as molecular platforms for heterologous proteins. Insertion into the centrally located c/e1 epitope leads to surface display, fusion to the C terminus to internal disposition of the foreign domains. However, symmetry-defined space restrictions on the surface and particularly inside the CLPs limit the size of usable heterologous fusion partners. Further, CLPs carrying differing foreign domains are desirable for applications such as multivalent vaccines, and for structure probing by distance sensitive interactions like fluorescence resonance energy transfer (FRET). Here, we report an in vitro co-assembly system for such mosaic-CLPs allowing successful CLP formation with a per se assembly-deficient fusion protein, and of CLPs from two different fluoroprotein-carrying fusions that exert FRET in an assembly-status dependent way.

Stepwise rotation of the gamma-subunit of EF(0)F(1)-ATP synthase observed by intramolecular single-molecule fluorescence resonance energy transfer.

The EF(0)F(1)-ATP synthase mutants bQ64C and gamma T106C were labelled selectively with the fluorophores tetramethylrhodamine (TMR) at the b-subunit and with a cyanine (Cy5) at the gamma-subunit. After reconstitution into liposomes, these double-labelled enzymes catalyzed ATP synthesis at a rate of 33 s(-1). Fluorescence of TMR and Cy5 was measured with a confocal set-up for single-molecule detection. Photon bursts were detected, when liposomes containing one enzyme traversed the confocal volume. Three states with different fluorescence resonance energy transfer (FRET) efficiencies were observed. In the presence of ATP, repeating sequences of those three FRET-states were identified, indicating stepwise rotation of the gamma-subunit of EF(0)F(1).

¿Puedes llamar hiperfrecuentadores a los pacientes por su alta frecuentación? / Could we call frequent attenders to patients because of their high frequency of attendance?

No disponible

Pharmacokinetics and pharmacodynamics of enalapril and its active metabolite, enalaprilat, at four different doses in healthy horses.

Pharmacokinetic and pharmacodynamic of IV enalapril at 0.50 mg/kg, PO placebo and PO enalapril at three different doses (0.50, 1.00 and 2.00 mg/kg) were analyzed in 7 healthy horses. Serum concentrations of enalapril and enalaprilat were determined for pharmacokinetic analysis. Angiotensin-converting enzyme (ACE) activity, serum ureic nitrogen (SUN), creatinine and electrolytes were measured, and blood pressure was monitored for pharmacodynamic analysis. The elimination half-lives of enalapril and enalaprilat were 0.67 and 2.76 h respectively after IV enalapril. Enalapril concentrations after PO administrations were below the limit of quantification (10 ng/ml) in all horses and enalaprilat concentrations were below the limit of quantification in 4 of the 7 horses. Maximum mean ACE inhibitions from baseline were 88.38, 3.24, 21.69, 26.11 and 30.19% for IV enalapril at 0.50 mg/kg, placebo and PO enalapril at 0.50, 1.00 and 2.00 mg/kg, respectively. Blood pressures, SUN, creatinine and electrolytes remained unchanged during the experiments.

Acute phase proteins in Andalusian horses infected with Theileria equi.

Clinical and laboratory findings were determined in 23 Andalusian horses in southern Spain that were positive for Theileria equi by PCR, including 16 mares at pasture (group A1) and seven stabled stallions (group B1). Five healthy mares at pasture (group A2) and five stabled stallions (group B2), all of which were negative for T. equi in Giemsa stained blood smears and by PCR, were used as controls. The most frequent clinical signs were anorexia, anaemia, depression and icterus (group A1), along with loss of performance or failure to train and depression (group B1). Thrombocytopoenia was evident in 5/7 horses in group B1. Lower serum iron concentrations were observed in both diseased groups compared with their respective control groups. There were no significant differences in APP concentrations between diseased and control groups; all affected horses had APP concentrations within reference limits. Serum haptoglobin, serum amyloid A and plasma fibrinogen concentrations were higher than the reference limits in 5/23, 3/23 and 1/23 diseased horses, respectively. It was concluded that horses with theileriosis exhibited only a mild systemic inflammatory response.

Influencia de la presión atmosférica sobre la incidencia de neumotórax espontáneo / Influence of atmospheric pressure on the incidence of spontaneous pneumothorax

INTRODUCCIÓN: Se analiza la relación entre incidencia de neumotórax espontáneo idiopático (NEI) y presión atmosférica (PA). MÉTODOS: Se incluyen 288 casos de NEI, 229 hombres y 59 mujeres. Se recogió PA el día del diagnóstico, PA en los 3 días previos y PA media mensual. Se analizó la asociación entre incidencia de NEI y PA mediante cálculo de razón de incidencia estandarizada (RIE) y regresión de Poisson. RESULTADOS: La PA el día del ingreso (media ± desviación típica) (1.017,9 ± 7 hectopascales [hPa]), fue más elevada que la PA media mensual (1.016,9 ± 4,1 hPa; p = 0,005). Hubo un patrón de distribución mensual del NEI, con mayor incidencia los meses de enero, febrero y septiembre y menor en abril. Cuando la PA fue inferior a 1.014 hPa se registraron menos casos de los que estadísticamente hubiera sido esperable encontrar (58/72 casos); sin embargo, cuando la PA fue superior a 1.019 hPa se registraron más casos de los esperados (109/82 casos) (RIE = 1,25; IC95%: 1,04-1,51). El riesgo de NEI aumentó 1,15 veces (IC 95%: 1,05-1,25; p = 0,001) por cada hPa de PA, independientemente del género, la edad y la PA media mensual. Se observó relación dosis-respuesta, con aumentos progresivos del riesgo (IRR = 1,06 cuando la PA fue 1.014-1.016 hPa; 1,17 cuando la PA fue 1.016-1.019 hPa y 1,69 cuando la PA fue superior a 1.019 hPa) (p de tendencia = 0,089). CONCLUSIONES: La PA es factor de riesgo para la aparición de neumotórax espontáneo idiopático

BACKGROUND: This study analyses the relationship between the incidence of idiopathic spontaneous pneumothorax (ISP) and atmospheric pressure (AP). METHODS: A total of 288 cases of ISP were included, 229 men and 59 women. The AP of the day of diagnosis, of the 3 prior days and the monthly average was registered. The association between the incidence of ISP and AP was analyzed by calculating standardized incidence ratio (SIR) and Poisson regression. RESULTS: The AP on the day of admission (mean ± standard deviation) (1,017.9 ± 7 hectopascals [hPa]) was higher than the monthly average AP (1,016.9 ± 4.1 hPa) (P=.005). There was a monthly distribution pattern of ISP with the highest incidence in the months of January, February and September and the lowest in April. When AP was less than 1,014 hPa, there were fewer cases registered than what would statistically have been expected (58/72 cases). In contrast, when the pressure was higher than 1,019 hPa, the registered cases were more than expected (109/82 cases) (SIR = 1.25; 95% CI: 1.04 to 1.51). The risk of ISP increased 1.15 times (95% CI: 1.05 to 1.25, P = .001) for each hPa of AP, regardless of sex, age and monthly average AP. A dose-response relationship was observed, with progressive increases in risk (IRR = 1.06 when the AP was 1,014-1016 hPa; 1.17 hPa when the AP was 1,016-1,019 hPa and 1.69 when AP was superior to 1,019 hPa) (P for trend = .089). CONCLUSION: The AP is a risk factor for the onset of idiopathic spontaneous pneumothorax