Impact of delivered tidal volume on the occurrence of intraventricular haemorrhage in preterm infants during positive pressure ventilation in the delivery room.

BACKGROUND AND OBJECTIVES: Delivery of inadvertent high tidal volume (VT) during positive pressure ventilation (PPV) in the delivery room is common. High VT delivery during PPV has been associated with haemodynamic brain injury in animal models. We examined if VT delivery during PPV at birth is associated with brain injury in preterm infants <29 weeks' gestation. METHODS: A flow-sensor was placed between the mask and the ventilation device. VT values were compared with recently described reference ranges for VT in spontaneously breathing preterm infants at birth. Infants were divided into two groups: VT<6 mL/kg or VT>6 mL/kg (normal and high VT, respectively). Brain injury (eg, intraventricular haemorrhage (IVH)) was assessed using routine ultrasound imaging within the first days after birth. RESULTS: A total of 165 preterm infants were included, 124 (75%) had high VT and 41 (25%) normal VT. The mean (SD) gestational age and birth weight in high and normal VT group was similar, 26 (2) and 26 (1) weeks, 858 (251) g and 915 (250) g, respectively. IVH in the high VT group was diagnosed in 63 (51%) infants compared with 5 (13%) infants in the normal VT group (P=0.008).Severe IVH (grade III or IV) developed in 33/124 (27%) infants in the high VT group and 2/41 (6%) in the normal VT group (P=0.01). CONCLUSIONS: High VT delivery during mask PPV at birth was associated with brain injury. Strategies to limit VT delivery during mask PPV should be used to prevent high VT delivery.

Prediction of COPD and Related Events Improves by Combining Spirometry and the Single Breath Nitrogen Test.

Chronic obstructive pulmonary disease (COPD) develops in small airways. Severity of small airway pathology relates to progression and mortality. The present study evaluated the prediction of COPD of a validated test for small airway disease, i.e. a slope of the alveolar plateau of the single breath nitrogen test (N2-slope). The N2-slope, spirometry, age, smoking habits, and anthropometric variables at baseline were obtained in a population-based sample (n = 592). The cohort was followed for first COPD events (first hospital admission of COPD or related conditions or death from COPD) during 38 years. During follow-up, 52 subjects (8.8%) had a first COPD event, of which 18 (3.0%) died with a first COPD diagnosis. In the proportional hazard regression analysis adjusted for age and smoking habits, the cumulative COPD event incidence increased from 5% among those with high forced expired volume in one second (FEV1) to 25% among those with low FEV1, while increasing from 4% among those with the lowest N2-slope to 26% among those with the highest. However, combining the N2-slope and FEV1 resulted in considerable synergy in the prediction of first COPD event and even more so when taking account of smoking habits. The cumulative COPD event incidence rate was 75% among heavy smokers with the highest N2-slope and lowest FEV1, and less than 1% among never smokers with the lowest N2-slope and highest FEV1. Thus, combining the results of the single breath N2-slope and FEV1 considerably improved the prediction of COPD events as compared to either test alone.

Valores de referencia del test de marcha de seis minutos en niños sanos / Reference values for the 6-minutes walking test in healthy Chilean children

Background: The 6-minutes walking test (6WT) is the ideal submaximal test for the evaluation and follow-up of patients with chronic respiratory diseases. There are no reference values (RV) for Chilean children using the American Thoracic Society guidelines. Aim: To generate 6WT reference values for Chilean children aged 6 to 14 years. Material and Methods: 6MW was evaluated in 192 healthy children (100 women) aged between 6 and 14 years. The test was carried out in a 30 m long indoor flat surface. Children also answered a survey about health problems and their weight and height were recorded. Results: The distance walked by women and men was 596.5 ± 57 and 625 ± 59.7 m respectively (p < 0.05). There was a significant correlation between the distance walked and height (r = 0.58), age (r = 0.56), weight (r = 0.54) and reserve heart rate (r = 0.21). Conclusions: These results can be used as reference values for the 6WT in Chilean children aged 6 to 14 years. They are similar to those reported abroad.