Acta Paediatr 81: 946-50. 1992
LETTERS TO THE EDITOR
High frequency jet ventilation Sir, Continuous positive airway pressure (CPAP) applied by the nasal route is widely used in treating neonates with respiratory distress syndrome (RDS) (1). However, intubation and initiation of conventional mechanical ventilation (CMV) are still necessary for a significant number of patients. The use of CMV is accompanied by barotrauma and has led to the emergence of new diseases such as bronchopulmonary dysplasia (2). In an attempt to find a technique to decrease the number of neonates needing intubation, we combined high frequency jet ventilation (HFJV) with nasal CPAP. After getting the approval of the hospital medical ethics committee and parent consents, 20 patients were selected. Criteria were established to select RDS patients of body weight less than 2000 g who were treated with nasal CPAP. Patients with intracranial haemorrhage, congenital malformations or who had been previously intubated were excluded. CPAP was applied by the MEDEC MK 78 Amsterdam infant ventilator via two nasal prongs with an internal diameter of 2-2.5 mm. A home-made high frequency jet ventilator was used to supply HFJV. The high frequency jet injector was positioned just before the nasal prongs. A frequency of 180 jets per minute, tidal volume 3 4 . 8 ml per jet and inspiratory time of 10 ms did not result in any change in the tubing pressures connected to the nasal CPAP device.
After patient selection, patients were randomly assigned to continue on nasal CPAP alone (group 1, N = 10) or received HFJV combined with nasal CPAP (group 2, N = 10). Criteria for patients' intubation were severe respiratory acidosis (pH less than 7.2) and/or frequent apneic attacks. Three patients in group 1 and four patients in group 2 needed intubation. The number of patients is too small for significant statistical calculations. However, our results suggest that nasal HFJV/ CPAP offers no advantage over nasal CPAP alone in preventing intubation of premature infants with RDS. We hope that our results will stimulate other investigators to study the technique on a larger number of patients.
References I . Kattwinkel J, Flemin D, Cha CC, Fanarrof AA, Klaus MH. A device for administration of continuous positive airway pressure by the nasal route. Pediatrics 1973;52:131-3 2. Northway WH Jr, Rosan RC, Porter DY. Pulmonary disease following respiratory therapy of hyaline membrane disease. N Engl J Med 1967;276:357-68 Ezzat S Aziz. L Deen, S Elkharieh, J Koppe' and M Boloens'. Depurtmenf s of Anaesthesiology and Neonutologq' , Academic Medical Center. Meibergdreef 9, I I05 AZ Amsterdam. The Nerherlands
Menarcheal age in East German girls Sir, Recently, Lindgren et al. ( I ) published data on the menarche in Swedish schoolgirls in 1990. Comparing results from different studies they concluded ". . . that the secular trend in menarcheal age has not only made a halt but might even have been reversed. . ." This may concern mainly girls born in 1971-1980. Using the status quo method in 1986, we analyzed data on menarcheal age in 8703 East German schoolgirls aged 8-16 years in a cross-sectional study. Girls with chronic diseases or disorders, including those with mental retardation were excluded from the study. The sample included East German girls of all social and economic classes, from urban as well as rural regions, and from all geographical regions in East Germany.
According to Lindgren et al., calculations were made by probit analysis (2), also. Based on this material and comparing previous data on menarcheal age in East German girls, we can underline this tendency of reversal of the accelerated menarcheal age effect. Using the values in Table I , the probit regression line is calculated as follows: Yprobit = - 23.2792 25.0462 'log Xtime
+
The regression line is well fitted to the data: df=6, r = 0.9958, P < 0.001. Using this regression equation, a mean menarcheal age of 13.46 years (SD 1.18 years) was found. This is the oldest age observed in the past 40 years in East German girls. Even if in the past, isolated
LETTERS TO THE EDITOR
High frequency jet ventilation Sir, Continuous positive airway pressure (CPAP) applied by the nasal route is widely used in treating neonates with respiratory distress syndrome (RDS) (1). However, intubation and initiation of conventional mechanical ventilation (CMV) are still necessary for a significant number of patients. The use of CMV is accompanied by barotrauma and has led to the emergence of new diseases such as bronchopulmonary dysplasia (2). In an attempt to find a technique to decrease the number of neonates needing intubation, we combined high frequency jet ventilation (HFJV) with nasal CPAP. After getting the approval of the hospital medical ethics committee and parent consents, 20 patients were selected. Criteria were established to select RDS patients of body weight less than 2000 g who were treated with nasal CPAP. Patients with intracranial haemorrhage, congenital malformations or who had been previously intubated were excluded. CPAP was applied by the MEDEC MK 78 Amsterdam infant ventilator via two nasal prongs with an internal diameter of 2-2.5 mm. A home-made high frequency jet ventilator was used to supply HFJV. The high frequency jet injector was positioned just before the nasal prongs. A frequency of 180 jets per minute, tidal volume 3 4 . 8 ml per jet and inspiratory time of 10 ms did not result in any change in the tubing pressures connected to the nasal CPAP device.
After patient selection, patients were randomly assigned to continue on nasal CPAP alone (group 1, N = 10) or received HFJV combined with nasal CPAP (group 2, N = 10). Criteria for patients' intubation were severe respiratory acidosis (pH less than 7.2) and/or frequent apneic attacks. Three patients in group 1 and four patients in group 2 needed intubation. The number of patients is too small for significant statistical calculations. However, our results suggest that nasal HFJV/ CPAP offers no advantage over nasal CPAP alone in preventing intubation of premature infants with RDS. We hope that our results will stimulate other investigators to study the technique on a larger number of patients.
References I . Kattwinkel J, Flemin D, Cha CC, Fanarrof AA, Klaus MH. A device for administration of continuous positive airway pressure by the nasal route. Pediatrics 1973;52:131-3 2. Northway WH Jr, Rosan RC, Porter DY. Pulmonary disease following respiratory therapy of hyaline membrane disease. N Engl J Med 1967;276:357-68 Ezzat S Aziz. L Deen, S Elkharieh, J Koppe' and M Boloens'. Depurtmenf s of Anaesthesiology and Neonutologq' , Academic Medical Center. Meibergdreef 9, I I05 AZ Amsterdam. The Nerherlands
Menarcheal age in East German girls Sir, Recently, Lindgren et al. ( I ) published data on the menarche in Swedish schoolgirls in 1990. Comparing results from different studies they concluded ". . . that the secular trend in menarcheal age has not only made a halt but might even have been reversed. . ." This may concern mainly girls born in 1971-1980. Using the status quo method in 1986, we analyzed data on menarcheal age in 8703 East German schoolgirls aged 8-16 years in a cross-sectional study. Girls with chronic diseases or disorders, including those with mental retardation were excluded from the study. The sample included East German girls of all social and economic classes, from urban as well as rural regions, and from all geographical regions in East Germany.
According to Lindgren et al., calculations were made by probit analysis (2), also. Based on this material and comparing previous data on menarcheal age in East German girls, we can underline this tendency of reversal of the accelerated menarcheal age effect. Using the values in Table I , the probit regression line is calculated as follows: Yprobit = - 23.2792 25.0462 'log Xtime
+
The regression line is well fitted to the data: df=6, r = 0.9958, P < 0.001. Using this regression equation, a mean menarcheal age of 13.46 years (SD 1.18 years) was found. This is the oldest age observed in the past 40 years in East German girls. Even if in the past, isolated
