Post-polio syndrome: epidemiologic and prognostic aspects in Brazil.

OBJECTIVES: To describe the clinical and epidemiological aspects of post-polio syndrome (PPS) and identify predictors of its severity. MATERIALS AND METHODS: 132 patients with PPS were selected at the Neuromuscular Disease Outpatient Clinic of the Federal University of São Paulo. Descriptive analysis was carried out and predictors of PPS severe forms were investigated using an unconditional logistic regression. RESULTS: The average age at onset was 39.4 years. The most common symptoms were fatigue (87.1%), muscle pain (82.4%) and joint pain (72.0%); 50.4% of the cases were severe. The following were associated with PPS severity: a < or =4-year period of neurological recovery (OR 2.8), permanent damage in two limbs (OR 3.6) and residence at the time of acute polio in a city with more advanced medical assistance (OR 2.5). CONCLUSIONS: Health professionals should carefully evaluate polio survivors for PPS and be aware of the implications of muscle overuse in the neurological recovery period.

Response to inspiratory resistive loading during sleep in normal children and children with obstructive apnea.

The response to inspiratory resistance loading (IRL) of the upper airway during sleep in children is not known. We, therefore, evaluated the arousal responses to IRL during sleep in children with the obstructive sleep apnea syndrome (OSAS) compared with controls. Children with OSAS aroused at a higher load than did controls (23 +/- 8 vs. 15 +/- 7 cmH(2)O. l(-1). s; P < 0.05). Patients with OSAS had higher arousal thresholds during rapid eye movement (REM) vs. non-REM sleep (P < 0.001), whereas normal subjects had lower arousal thresholds during REM (P < 0.005). Ventilatory responses to IRL were evaluated in the controls. There was a marked decrease in tidal volume both immediately (56 +/- 17% of baseline at an IRL of 15 cmH(2)O. l(-1). min; P < 0.001) and after 3 min of IRL (67 +/- 23%, P < 0.005). The duty cycle increased. We conclude that children with OSAS have impaired arousal responses to IRL. Despite compensatory changes in respiratory timing, normal children have a decrease in minute ventilation in response to IRL during sleep. However, arousal occurs before gas-exchange abnormalities.

Discordant effects of alkalosis on elevated pulmonary vascular resistance and vascular reactivity in lamb lungs.

OBJECTIVES: After an initial vasodilator response to alkalosis, many children with pulmonary hypertension exhibit marked pulmonary vascular reactivity despite continued alkalosis therapy. This study sought to a) identify the mediator of alkalosis-induced pulmonary vasodilation in isolated lamb lungs; b) determine whether alkalosis-induced pulmonary vasodilation decreases over time in this model; and c) determine whether alkalosis enhanced vascular reactivity to subsequent pressor stimuli. DESIGN: Prospective, interventional study. SUBJECTS: Isolated perfused lungs from 1-month-old lambs. INTERVENTIONS: Hypocarbic alkalosis, hypoxia, and infusion of the thromboxane mimetic agent U46619 MEASUREMENTS AND MAIN RESULTS: Pulmonary artery pressure was measured at constant flow, so a change in pressure reflects change in resistance. Hypoxic pulmonary artery pressure was compared after 20 and 100 mins of hypocarbic alkalosis or normocarbia in control and cyclooxygenase-inhibited lungs. Pulmonary artery dose responses to U46619 were then measured in control lungs. Responses to hypoxia and U46619 were also compared after 60-80 mins of hypocarbic or normocarbic normoxia. Hypocarbic alkalosis acutely reduced hypoxic pulmonary vascular resistance, and this was sustained for at least 100 mins. Cyclooxygenase inhibition blocked this vasodilation, suggesting that it was mediated by dilator prostaglandins. However, subsequent reactivity to U46619 was enhanced in hypoxic alkalotic lungs, and both hypoxia and U46619 caused significant vasoconstriction in normoxic alkalotic lungs. CONCLUSIONS: Alkalosis caused sustained vasodilation when pulmonary vascular resistance was high but either failed to attenuate or enhanced vascular reactivity to subsequent pressor stimuli.

Maturational changes in ovine pulmonary vascular responses to inhaled nitric oxide.

Developmental changes in modulation of pulmonary vasomotor tone by endothelium-derived nitric oxide (EDNO) may reflect maturational differences in endothelial synthesis of and/or vascular smooth muscle response to nitric oxide. This study sought to determine whether pulmonary vascular sensitivity and responsiveness to nitric oxide change during newborn development, and whether this is related to changes in guanylate cyclase activity. Pulmonary artery dose-responses to inhaled nitric oxide (iNO, 0.25-100 parts per million) were measured in hypoxic, indomethacin-treated, isolated lungs from 1-day (1-d)- and 1-month (1-m)-old lambs. The lungs of 1-m-old lambs were ventilated with 4% (oxygen) O2, and lungs of 1-d-old lambs were ventilated with either 4% or 7% O2 in order to achieve similar stimuli or vasomotor tone. Cyclic guanosine monophosphate (cGMP) concentrations in the perfusate were measured at iNO concentrations of 0, 5, and 100 parts per million (ppm). Basal and stimulated pulmonary guanylate cyclase activity was also measured in lung extracts in vitro. The effects of iNO were similar in both 1-d groups, even though baseline hypoxic tone was significantly higher in 1-d lungs ventilated with 4% O2 than with 7% O2. Furthermore, both the 1-d 7% O2 and 1-d 4% O2 lungs exhibited greater responsiveness and sensitivity to iNO than 1-m lungs. Perfusate cGMP concentrations and soluble guanylate cyclase activity were higher under stimulated than basal conditions, but neither differed statistically between 1 d and 1 m. These data suggest that pulmonary vascular responsiveness and sensitivity to nitric oxide decrease with age, but the mechanisms underlying these maturational changes require further investigation.

Relative effects of cyclooxygenase and nitric oxide synthase inhibition on vascular resistances in neonatal lamb lungs.

Effective attenuation of pulmonary vasoconstriction is essential during early postnatal development when increased pulmonary vascular resistance (PVR) may lead to a resumption of right-to-left shunting across fetal channels. In addition, modulation of venous resistance contributes to normal lung fluid balance. This study was designed to identify the relative modulating effects of endothelium-derived nitric oxide (EDNO) and dilator prostaglandins (PG) on normoxic and hypoxic pulmonary vasomotor tone in young newborns. Total and segmental PVR were measured using inflow-outflow and double occlusion techniques in isolated lungs of 6-h-old lambs studied under control conditions or after blocking PG and/or EDNO synthesis with indomethacin and/or N omega-nitro-L-arginine, respectively. During normoxia, both indomethacin and N omega-nitro-L-arginine were required to increase total PVR, but EDNO appeared to have the greater modulating effect. Indomethacin markedly enhanced hypoxic pulmonary vasoconstriction of large and small arteries and small veins, whereas N omega-nitro-L-arginine caused a lesser, but significant, increase in hypoxic pulmonary vasoconstriction of small arteries and veins, suggesting that dilator PG played the dominant modulating role during hypoxia. In addition, PG synthesis appeared to be enhanced after inhibition of EDNO synthesis. In contrast, indomethacin caused a decrease in venous resistance, suggesting that constrictor prostanoids had a greater effect than dilator PG on this segment. EDNO had a modest modulating effect on venous resistance in these lungs. These data suggest that dilator PG and EDNO exert complementary effects in attenuating total and segmental PVR during normoxia and hypoxia in 6-hold lamb lungs.

Adult respiratory distress syndrome in newborns: 5 cases.

Aiming to set out the occurrence of the Adult Respiratory Distress Syndrome (ARDS) in the neonatal period, and according to recent descriptions in literature, we prospectively analyzed 5 cases. The criterion adopted to characterize ARDS was the expanded definition of the syndrome suggested by Murray & Matthay, (10), conjointly with non-invasive cardiac monitoring, to exclude pulmonary edema resulting from myocardial dysfunction. For each case, evolution was briefly described, as well as the predisposing conditions associated to the clinical score punctuation for diagnosis, stressing the importance of adequate identification and fastest possible management of such source of systemic effects. Upon admission at the intensive care unit (Ped. ICU), the five cases were either related to sepsis or to the syndrome of multiple organ failure, or to both. Both syndromes were essentially triggered by severe anoxia neonatorum, respiratory distress of the newborn and/or previous hospitalization with hypoxemia and use of a higher inspired fraction of oxygen. The primary causes of death were related to uncontrolled infection or shock, and not directly related to pulmonary failure.