A comparison of the hemodynamic and respiratory effects of surfactant instillation during interrupted ventilation versus noninterrupted ventilation in rabbits with severe respiratory failure

The purpose of this study was to evaluate whether avoiding interruption of ventilation during surfactant instillation improves the effects on lung function and surfactant distribution and whether it prevents the adverse effects on blood pressure and cerebral blood flow. The study was performed using rabbits with severe respiratory failure induced by lung lavages. These rabbits were randomized to 99mTc-Nanocoll labeled surfactant instillation through a side lumen of the endotracheal tube without interrupting ventilation or instillation during a short interruption of ventilation. After surfactant instillation with interruption of ventilation, PaO2 rose from 8.7+/-1.3 to 24.9+/-6.4 kPa (mean+/-SEM). Without interruption, PaO2 rose from 8.4+/-0.8 to 32.4+/-4.3 kPa. PaCO2 decreased with interruption from 4.69+/-0.51 to 3.61+/-0.26 kPa and without interruption from 5.06+/-0.41 to 4.13+/-0.23 kPa. Dynamic and static compliance indices were not statistically different after both procedures. Surfactant distribution tended to be less nonuniform after instillation without interrupting ventilation. In contrast, avoidance of interruption of ventilation resulted in less uniform lobar distribution and less peripheral deposition of surfactant. By instillation with interruption, blood pressure increased quickly (28+/-6.6%), followed by a 22+/-5.3% decrease. Blood pressure increased quickly (16+/-4.2%), followed by a 40+/-10% decrease by surfactant instillation without interruption. Cerebral blood flow, measured by an ultrasonic transit time flow probe on the carotid artery, increased quickly (45+/-14%), followed by a 64+/-11% decrease with interruption, whereas it increased 15+/-4.9% (p = 0.06 versus with interruption) and decreased 61+/-13% without interruption of ventilation. Therefore, avoiding interruption of ventilation during surfactant instillation tends to prevent the potential adverse effects of a rapid rise in cerebral blood flow, and furthermore, tends to improve uniformity of surfactant distribution, whereas having no detrimental effect on respiratory function.     

Cerebral blood flow velocity variability in infants receiving assisted ventilation.

Cerebral blood flow velocity was measured using Doppler ultrasonography in 20 babies who weighed less than 2500 g at birth and who were receiving assisted ventilation; their patterns of spontaneous respiration were recorded simultaneously. The babies were induced to breathe synchronously or asynchronously with the ventilator by manipulating the inspiratory and expiratory time settings. The variability of cerebral blood flow velocity (coefficient of variation) was calculated from the area of the maximum Doppler frequency shift envelope for 10 cardiac cycles from 211 recordings made on 42 occasions, and was greatest within 12 hours of birth after which it fell progressively over the next 48 hours. Variability of cerebral blood flow velocity was significantly greater when the infants were breathing out of synchrony with the ventilator (median 11%, interquartile range 8-14%) than when they were either apnoeic (median 5%, 3-7%), or breathing synchronously with the ventilator (median 5%, 3-6%).     

Surfactant substitution in very small premature infants

In addition to the established treatment of neonatal respiratory distress syndrome by oxygen supplementation, artificial ventilation and thermoneutrality, substitution of surfactant offers a new therapeutic perspective. Up to now, either artificial mixtures of surface active components or surfactant extracts from minced animal lungs, lung lavage fluid, or human amniotic fluid have been used in controlled trials of prophylactic and rescue surfactant treatment. Meta-analysis of controlled prevention trials including about 2,400 preterm infants shows decreased mortality (21% in controls, 9.5% in infants treated with natural preparations, p less than 0.001; 17% in controls, 11% in infants treated with artificial preparations, p less than 0.001) and fewer complications of artificial ventilation (pneumothorax: 24 vs. 7.2% with natural preparations, p less than 0.001; 20 vs. 15% with artificial preparations, p less than 0.05). In rescue studies on more than 1,900 preterm infants, natural surfactant preparations decreased complications of artificial ventilation such as pulmonary interstitial emphysema and pneumothorax (32 vs. 13%, p less than 0.001). Although the immediate effect of artificial preparations is mild, the incidence of pneumothorax also could be reduced (30 vs. 19%, p less than 0.001). Mortality could be reduced by 1/3 with natural (31 vs. 20%, p less than 0.001) and with artificial preparations (23 vs. 16%, p less than 0.01). The incidence of bronchopulmonary dysplasia and intracerebral hemorrhage, however, did not drop significantly. Severe adverse side effects of this treatment seem to be rare. There are, however, potential hazards of surfactant substitution. Its use should be restricted to fully staffed and equipped neonatal intensive care units.     

胎粪吸入性肺炎应用常频与高频通气的研究

目的　 评估常频通气和高频通气治疗胎粪吸入性肺炎 (MAS)所致呼吸衰竭的临床与实验对比疗效。 方法 　实验方面 :健康白兔 ,气管注入胎粪混悬液 ( 3～ 5ml/kg) ,呼吸衰竭模型出现后随机分组 :①继续常频通气 (CMV) 3h后转为高频通气 (HFV) 3h(CMV HFV组 ) ;②转为HFV 3h后再转为CMV 3h(HFV CMV组 )。 2 0例MAS患儿入院后即用CMV治疗 ,当所用吸入氧浓度 (FiO2 ) >0 82h左右 ,经皮氧饱和度 (TcPO2 )仍 <90 %,改为HFV治疗 ;当FiO2 >0 82h左右 ,TcPO2 能维持在90 %以上 ,继续用CMV治疗。 10例继续应用CMV治疗 ,10例改用HFV治疗。 结果 　动物出现呼吸衰竭模型时 ( 0h)的氧合指数 (OI)二组无差异 ,CMV HFV组在治疗后 3hOI无明显变化 ,至 6hOI有上升 ;HFV CMV组治疗后 3hOI较 0h时有下降 ,两组动物治疗后 3h的OI的组间比较有差异。 2 0例患儿中 ,CMV组治愈 7例 ,死亡 2例 ,放弃 1例 ;HFV组治愈 7例 ,放弃 2例 ,死亡1例。HFV组患儿治疗后 1hOI较 0h有下降 ,至治疗后 6h ,OI与 0h比较差异显著 ;CMV组治疗后 1hOI有明显下降 ,但至治疗后 6h下降幅度不明显。二组患儿的呼吸机应用时间和用氧时间均无差异。 结论 　MAS用HFV治疗后的氧合作用较CMV改善明显和吸入氧浓度下降迅速     

Prolonged ventilation of the premature newborn rabbit after treatment with natural or apoprotein-based artificial surfactant

Premature rabbit neonates (gestational age 27 days) were treated at birth with natural surfactant purified from chloroform extracts of porcine lung lipids either by acetone precipitation (Surfactant CK, n=10) or liquid gel chromatography (Curosurf, n=22). Another group of animals received artificial surfactant reconstituted from isolated low molecular weight (15 K) apoproteins and synthetic dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylglycerol (DPPG) (Aposurf, n=10). The phospholipid concentrations of the preparations were adjusted to provide the same individual dose of DPPC for each group of treated animals (3 or 4 mg). In comparison with untreated controls from the same litters, there was a 4–7-fold enhancement of lungthorax compliance in all groups of surfactant-treated animals during a 3-h period of artificial ventilation. The average initial (20 min) compliance value was lower in the Aposurf-treated group than in animals receiving natural surfactant preparations, but the difference between the groups gradually diminished and was no longer statistically significant during the 2nd and 3rd h of artificial ventilation. Judged from the fall in tidal volume during ventilation with a short expiration phase (0.17 instead of 0.75s), the apoprotein-based artificial surfactant was also less effective in stabilizing the lungs. A similar conclusion could be drawn from data on alveolar expansion in histological sections, evaluated by automated image analysis. Alveolar volume density was improved only moderately in the Aposurf-treated group (0.24 vs. 0.14; P=0.05), whereas the expected, prominent increase in this parameter was observed in both groups of natural surfactant-treated animals (0.48–0.62 vs. 0.14; P<0.001). We conclude that a physiologically active artificial surfactant can be prepared from the smaller (15 K) apoproteins, DPPC and DPPG; the in vivo effects of this preparation were clearly beneficial, yet inferior to those obtained with the same dose of natural surfactant.Abbreviations DPPC dipalmitoylphosphatidylcholine - DPPG dipalmitoylphosphatidylglycerol - RDS respiratory distress syndrome - V_v volume density - CV coefficient of variation - dV_T tidal volume reduction - K kilodalton(s)     

Severe neonatal respiratory distress syndrome treated with the isolated phospholipid fraction of natural surfactant

Ten newborn infants (795-1680 g) with severe respiratory distress syndrome (RDS) were treated with the isolated phospholipid fraction of bovine or porcine surfactant, which was administered via the airways (dose 200 mg/kg), at a median age of 10.5 h. Before receiving surfactant, all the infants were on artificial ventilation (FiO2 0.6-1.0). Within 2 h after surfactant replacement, the arterial-to-alveolar PO2 ratio increased from 0.1 to 0.35. There was a concomitant improvement in lung aeration on the chest roentgenograms and a significant reduction in the right-to-left shunt. Four patients died of cerebral hemorrhage; two of them also had a patent ductus arteriosus. One surviving infant developed bronchopulmonary dysplasia, and another succumbed 8 months later to the sudden infant death syndrome. No antibodies against surfactant were detected in the sera of the survivors. Since our results show a significant improvement in lung function after replacement therapy, the efficacy of this new surfactant preparation should be further tested in randomized clinical trials.     

Instillation rate effects of Exosurf on cerebral and cardiovascular haemodynamics in preterm neonates.

The acute effects of surfactant instillation rate on the cerebral and cardiovascular haemodynamics were studied in a randomised trial of 27 preterm neonates with respiratory distress syndrome (RDS). Cerebral blood flow velocity (CBFV), mean arterial blood pressure (MABP), blood gases and electroencephalogram (EEG) were continuously recorded before, during, and for at least 10 minutes after the administration of surfactant. The measurements were repeated one, three, and six hours later. Left ventricular output (LVO) and ductal patency were assessed 10 minutes before and then one, three, and six hours after surfactant administration. Surfactant (Exosurf) was instilled rapidly over five minutes in 13 infants and slowly over 15 minutes in 14 infants. The rapid group showed a significant but transient increase (mean 38%) in CBFV, a rise strongly related to an increase in carbon dioxide tension. No significant change in CBFV was observed in the slow group. There were no significant changes in EEG, MABP, LVO, or ductal shunting in either group. The findings suggest that rapid instillation of Exosurf leads to an increase in CBFV and partial carbon dioxide pressure (PCO2) and requires a close monitoring of blood gases to maintain adequate ventilation. Furthermore, the findings should alert clinicians to the need for slow infusion of Exosurf.     

Cerebral hemodynamic effects of treatment with modified natural surfactant investigated by near infrared spectroscopy.

The purpose of this study was to investigate the effects on cerebral hemodynamics of administering modified natural surfactant (Curosurf, 200 mg.kg-1) to infants requiring mechanical ventilation for hyaline membrane disease. Observations were made using near infrared spectroscopy on 20 infants for between 26 and 109 (median 57) min before and 22 to 112 (median 46) min after surfactant instillation. Changes in cerebral oxyhemoglobin concentration and cerebral blood volume (CBV) were monitored continuously; cerebral blood flow, oxygen delivery, and the response of CBV to changes in arterial carbon dioxide tension were measured while the infants were stable shortly before and after surfactant was given. Cerebral oxyhemoglobin concentration fell transiently in all infants immediately after surfactant by a median of -0.21 (range -0.46 to 0.05) mL x 100 g-1, but quickly recovered so that the median change during the 10 min after surfactant was 0.01 (-0.46 to 0.46) mL x 100 g-1. Alterations in CBV also occurred ranging from -0.44 to 0.40 (median 0) mL x 100 g-1, which represented -12 to 16% of total CBV; these changes rapidly resolved. When the infants were stable before and after surfactant, the values for mean (SD) cerebral blood flow were 20.5 (7.5) and 23.1 (5.2) mL.100 g-1 x min-1, respectively (n = 9); for mean cerebral oxygen delivery, values were 2.71 (0.89) and 3.15 (0.73) mL x 100 g-1 x min-1 (n = 9); and for response of CBV to changes in arterial carbon dioxide tension, they were 0.14 (0.09) and 0.11 (0.11) mL x 100 g-1 x kPa-1 (n = 16); these changes were not statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)     

Asymmetry of fetal cerebral hemispheres: in utero ultrasound study

AIMS: To assess survival and neurodevelopmental outcome following prolonged ventilation beyond 27 or 49 days of postnatal life in neonates treated with antenatal steroids and surfactant. METHODS: The medical records of 84 babies born in 1994-1996 requiring ventilation after 27 postnatal days at Liverpool Women's Hospital were reviewed to determine the duration of mechanical ventilation, survival, and neurodevelopmental outcome at 3 years of age. RESULTS: Fifty six babies were mechanically ventilated after 27 postnatal days but for less than 50 days; 48 (86%) survived to 3 years. Twenty six (54%) of the survivors had normal neurodevelopment at 3 years and seven (15%) had only mild disability. Twenty eight babies were ventilated after 49 postnatal days; 14 survived to 3 years. Five of these survivors were neurodevelopmentally normal at 3 years and two had mild disability. CONCLUSIONS: Survival decreases with more prolonged ventilation. When antenatal steroids and postnatal surfactant are used, there appears to be improved survival and neurodevelopmental outcome in preterm babies who require prolonged ventilation.     

Randomized study of nasal continuous positive airway pressure in the preterm infant with respiratory distress syndrome

Aim: To evaluate whether very preterm babies can be extubated successfully to nasal continuous positive airway pressure (nCPAP) within one hour of birth after receiving one dose of surfactant in the treatment of respiratory distress syndrome (RDS). Methods: Forty-two infants of 25 to 28[Formula: See Text] wk of gestation were intubated at birth and given one dose of surfactant. They were then randomized within one hour of birth to either continue with conventional ventilation or to be extubated to nCPAP. Results: Eight out of 21 (38%) babies randomized to nCPAP did not require subsequent reventilation. (Ventilation rates of 62% vs 100%, p = 0.0034). The smallest baby successfully extubated weighed 745 g. There were also significantly fewer infants intubated in the nCPAP group at 72 h of age (47% vs 81%, p = 0.025). There was no significant difference between the two groups in the number of babies that died, developed chronic lung disease or severe intraventricular haemorrhage.

Conclusion: A significant number of very preterm babies with RDS can be extubated to nCPAP after receiving one dose of surfactant. nCPAP is a potentially useful modality of respiratory support even in very premature infants.     

Stable microbubble test on tracheal aspirate for the diagnosis of respiratory distress syndrome

BACKGROUND: Exogenous surfactant should be used as early as possible in the presence of respiratory distress syndrome (RDS), but diagnosis may only become clear late in the course of the disease. The stable microbubble test (SMT) in the tracheal aspirates could help in the decision to give early surfactant to preterm babies with respiratory distress. OBJECTIVES: The objective of this study was to evaluate the accuracy of the SMT on tracheal aspirate for the diagnosis of RDS in newborns requiring mechanical ventilation. METHODS: The test was performed on specimens obtained from 74 infants requiring mechanical ventilation, through routine suctioning. RESULTS: Patients with RDS and meconium aspiration syndrome (MAS) had a significantly lower stable microbubble count than non-RDS and non-MAS patients. Preterm infants without RDS had a significantly higher microbubble count than preterm babies with RDS and a similar count to that of term babies. Considering a cutoff point of 120 microbubbles/mm(2) for the diagnosis of RDS, the sensitivity of the microbubble test was 96.3% (95% CI: 79.1-99.8) and the specificity 97.6% (95% CI: 85.9-99.9). CONCLUSIONS: The SMT on tracheal aspirates is accurate for RDS diagnosis and may be useful to support the decision to give surfactant to newborns on mechanical ventilation.     

A randomised control study of partial liquid ventilation after airway lavage with exogenous surfactant in a meconium aspiration syndrome animal model

AIMS: To test the hypothesis that lavage with exogenous surfactant before partial liquid ventilation in meconium aspiration syndrome (MAS) would improve debris removal, and therefore the effectiveness of partial liquid ventilation. METHODS: 12 newborn piglets were randomised into 4 groups, partial liquid ventilation or gas ventilation, with and without surfactant lavage. Physiological and blood gas data were compared between groups by analysis of variance. RESULTS: Arterial oxygen pressure (PaO(2)) was improved in the group treated with surfactant lavage when compared with the group not receiving surfactant. PaO(2) in the group receiving surfactant lavage followed by partial liquid ventilation was further improved when compared with the group treated with surfactant lavage followed by gas ventilation and the group receiving partial liquid ventilation alone. CONCLUSION: The effectiveness of partial liquid ventilation in MAS might be enhanced by pretreatment with exogenous surfactant bronchial lavage.     

Partial liquid ventilation and nitric oxide in experimental acute lung injury

OBJECTIVE: To investigate the effects of inhaled nitric oxide (iNO) and partial liquid ventilation (PLV) on oxygenation and pulmonary haemodynamics in acute lung injury (ALI), and to assess their effects on lung function, systemic haemodynamics and lung injury. METHODS: Using saline lung lavage, ALI was induced in 18 piglets. A control group was ventilated with conventional mechanical ventilation (CMV) for 2 h. An iNO-first group received iNO for the first hour and then iNO with PLV. A PLV-first group received PLV for the first hour and then PLV with iNO. Variables were measured at baseline, 5 min postlavage, and at 1 h and 2 h postlavage. RESULTS: During the first hour, both treatment groups showed improvement in oxygenation index (OI). At 2 h, the dif-ferences in OI were statistically significant (P = 0.037), with a mean +/- SD of 23.8 +/- 20.7 in the control group, 4.4 +/- 0.9 in the PLV-first group and 6.5 +/- 3.1 in the iNO-first group. The OI was similar in both treatment groups (P = 0.178). At 2 h, the pulmonary artery pressure (PAP) was significantly different (P = 0.04) between groups, with a mean +/- SD PAP of 36.3 +/- 7.2 mmHg in the control group, 27.4 +/- 4.0 mmHg in the PLV-first group and 30.0 +/- 4.1 mmHg in the iNO-first group. The PAP was similar in both treatment groups (P = 0.319). CONCLUSION: In ALI, oxygenation and pulmonary hypertension are improved with PLV and iNO given together, regardless of the order in which they are commenced.     

Continuous Positive Airway Pressure for Spontaneously Breathing Premature Infants with Respiratory Distress Syndrome

Objective

To analyze the outcome of inborn preterm neonates with respiratory-distress-syndrome(RDS), using the approach of administering nasal-continuous-positive-airway-pressure(CPAP) alone and administering surfactant only if they require mechanical ventilation(MV).

Methods

All preterm neonates diagnosed as RDS from 01-May-2006 to 10-July-2010 were prospectively enrolled for the study at a referral centre in India. Nasal-CPAP alone was administered to all spontaneously breathing neonates. Surfactant was administered in babies <28 wk gestational age if the baby was intubated for resuscitation at birth. For the remaining babies, surfactant was administered if the baby required ventilation for RDS in first 72 h. The primary outcome assessed was survival to discharge.

Results

Of the 83 babies with RDS, 33(39.76%) neonates needed MV of which one baby was transferred due to non-availability of ventilator. Of the remaining 32 babies administered MV, 31 were administered surfactant. Fifty (61.24%) babies were managed with CPAP alone. Overall, 72/82(87.8%) babies managed at the authors’ center survived the neonatal period, and 71/82(86.8%) babies were discharged to home. Among the neonates who were ventilated, 26/32(81.25%) survived the neonatal period, and 25/32(78.12%) were discharged home. Among the babies receiving CPAP, 46/50 (92%) survived and were discharged to home.

Conclusions

Institution of CPAP alone in all spontaneously breathing preterm babies with RDS and administration of surfactant to only those needing MV reduces the need for intubations and surfactant administration without affecting the outcome adversely. Extreme preterms with RDS, however, may be given surfactant if they happen to be intubated for resuscitation at birth.

     

Randomized European multicenter trial of surfactant replacement therapy for severe neonatal respiratory distress syndrome: single versus multiple doses of Curosurf.

There is now convincing evidence that the severity of neonatal respiratory distress syndrome can be reduced by surfactant replacement therapy; however, the optimal therapeutic regimen has not been defined. This randomized European multicenter trial was designed to determine whether the beneficial effects of a single large dose of Curosurf (200 mg/kg) in babies with severe respiratory distress syndrome (arterial to alveolar oxygen tension ratio approximately 0.10) could be enhanced by using multiple doses of surfactant. Preterm neonates (birth weight 700 to 2000 g) with severe respiratory distress syndrome requiring artificial ventilation with fraction of inspired oxygen greater than or equal to 0.6 were randomized into two groups at an age of 2 to 15 hours. Both groups received the usual dose of Curosurf (200 mg/kg) immediately after randomization. In neonates randomized to receive multiple-dose treatment, two additional doses of Curosurf (100 mg/kg each) were instilled into the airways (12 and 24 hours after the initial dose) provided that the patients still needed artificial ventilation with fraction of inspired oxygen greater than 0.21. In both groups (single dose: n = 176, multiple doses: n = 167) there was a rapid improvement in oxygenation as reflected by a threefold increase in arterial to alveolar oxygen tension ratio within 5 minutes after surfactant instillation (P less than .001), and peak inspiratory pressure and mean airway pressure could be reduced significantly during the first 6 hours after surfactant treatment. In addition, ventilatory requirement (peak inspiratory pressure, ventilatory efficiency index) was reduced in the multiple-dose group 2 to 4 days after randomization (P less than .05 to .01).(ABSTRACT TRUNCATED AT 250 WORDS)     

Surfactant tracheobronchial lavage for the management of a rabbit model of meconium aspiration syndrome

We evaluated the effect of tracheobronchial lavage with diluted surfactant solution (bovine lipid extract surfactant, bLES) in a rabbit model of meconium aspiration. All animals were anaesthetized, tracheotomized and given 3-4 ml/kg of 25% slurry of human meconium into the endotracheal tube and mechanically ventilated for 1 h. The animals were then randomly assigned to surfactant lavage (n = 12) with 15 ml/kg of diluted surfactant at a concentration of 5.4 mg phospholipid/ml administered in aliquots of 2 ml; or simple endotracheal suction (control n = 12) when the oxygenation index (OI) was >/=15. Changes in the arterial blood gases and the histomorphological and radiological appearances of the lungs were recorded. The OI and arterial/alveolar oxygen tension (a/A PO2) of the surfactant lavage group improved significantly at 5 min post-treatment, and these improvements were observed throughout the ensuing 4 h of ventilation. There was significantly more solid content recovered by surfactant lavage compared with the control group (p = 0.0001). Radiologically, the post-treatment air space opacification scores of the lavage group were significantly lower compared with the control (p = 0.002). The post-treatment radiographs of the lavage-treated rabbits were rated by the radiologist, who was blinded to the treatment groups, as much improved in 5 and improved in 4, whereas the control rabbits were rated as much worse in 3 and worse in 4. Histological examination showed the lungs of the lavaged rabbits had significantly more normal airway (p < 0.0001), more fields showing completely normal airspace (p = 0.0001) and less fields showing severe overdistension with meconium (p = 0.0005). We concluded that lavage with diluted surfactant solution effectively washed out the meconium, improved gases exchanges, and improved the histological and radiological appearances in the rabbit model of MAS.     

High-frequency oscillatory ventilation in pediatric patients with acute respiratory failure.

OBJECTIVE: To evaluate the effectiveness of high-frequency oscillatory ventilation (HFOV) in pediatric patients with acute respiratory failure, failing conventional ventilation. DESIGN: A prospective, clinical study. SETTING: Tertiary care pediatric intensive care unit. PATIENTS: Twenty pediatric patients (ages 12 days to 5 yrs) with acute respiratory failure (pneumonia, 14; sepsis with acute respiratory distress syndrome, 3; pulmonary edema as a complication of upper airway obstruction, 2; salicylate intoxication with acute respiratory distress syndrome, 1), failing conventional ventilation (median alveolar-arterial oxygen difference [P(A-a)O2] 578 [489-624] torr, median oxygenation index 26 [21-32]. INTERVENTIONS: HFOV was instituted after a median length of conventional ventilation of 15.5 (3.3-43.5) hrs. MEASUREMENTS AND MAIN RESULTS: Ventilator settings, arterial blood gases, oxygenation index, and P(A-a)O2 were recorded before HFOV (0 hrs) and at predetermined intervals during HFOV and compared using the one-way Friedman rank-sum procedure and a two-tailed Wilcoxon matched-pairs test. Initiation of HFOV caused a significant decrease in FiO2 at 1 hr that continued to 24 hrs (p 相似文献   

Glycemic level in mechanically ventilated children with bronchiolitis.

OBJECTIVE: To evaluate in children with bronchiolitis requiring mechanical ventilation the association between blood glucose level and duration of mechanical ventilation and pediatric intensive care unit (PICU) stay. DESIGN: Retrospective cohort study. SETTING: University hospital PICU. PATIENTS: Children admitted to a university hospital PICU over a period of 3 yrs. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Demographic data, infection with respiratory syncytial virus, history of prematurity, mechanical ventilator settings, and use of inotrope during illness were noted. In addition, C-reactive protein, alanine transaminase, and glucose levels were recorded. Data from 50 children with median (interquartile range) age of 2.2 (1.3-4.7) months were analyzed. There were 37 boys, 21 children had been premature babies, and 30 children were positive for respiratory syncytial virus. Hyperglycemia at any time was frequent (peak glucose > or =6.1 mmol/L [110 mg/dL] in 98% and >8.3 mmol/L [150 mg/dL] in 72%). Children with sustained hyperglycemia were more likely to be boys with higher alanine transaminase and C-reactive protein, requiring inotrope (p < .05). These children are more likely to have required high-frequency oscillation ventilation, required higher airway pressures, and had longer duration of mechanical ventilation and PICU stay (p < .05). Peak glucose and sustained peak glucose were not independently associated with duration of mechanical ventilation or PICU stay. Multiple regression showed that age, C-reactive protein, the need for inotrope, and respiratory syncytial virus infection were independent factors associated with duration of PICU stay. Glucose level was not a factor. CONCLUSIONS: Our findings show that hyperglycemia is frequent in children with bronchiolitis requiring mechanical ventilation, but we failed to show that this phenomenon was independently associated with prolonged duration of mechanical ventilation or PICU stay. Our observations raise the question whether tight glycemic control should be used in children with bronchiolitis.     

不同机械通气方式联合肺表面活性物质对新生儿急性肺损伤/急性呼吸窘迫综合征疗效比较

目的 比较高频振荡通气+肺表面活性物质 （HFOV+PS）、常频机械通气+肺表面活性物质 （CMV+PS）、常频机械通气 （CMV）3种治疗方式对新生儿急性肺损伤/急性呼吸窘迫综合征 （ALI/ARDS）的临床疗效。方法 纳入ALI/ARDS新生儿136例 （ALI73例,ARDS63例）,其中HFOV+PS组45例,CMV+PS组53例,CMV组38例,前两组应用肺表面活性物质气管内滴入 （70~100mg/kg）。分别检测机械通气0h、12h、24h、48h、72h的PaO2、PaCO2、PaO2/FiO2、氧合指数 （OI）、呼吸指数 （RI）。结果 机械通气12h、24h、48h时HFOV+PS组的PaO2高于CMV+PS组和CMV组,PaCO2低于CMV+PS组和CMV组 （P < 0.05）;在机械通气12h、24h、48h、72h时HFOV+PS组PaO2/FiO2高于CMV+PS组和CMV组,OI、RI低于CMV+PS组和CMV组 （P < 0.05）;HFOV+PS组机械通气时间、用氧时间均低于CMV+PS组和CMV组 （P < 0.05）;3组气漏、颅内出血发生率及治愈率比较差异无统计学意义。结论 与单纯CMV以及CMV联合PS治疗相比,HFOV联合PS更可改善ALI/ARDS新生儿的肺功能,缩短通气时间及用氧时间,且不增加并发症的发生。     

High frequency oscillation ventilation compared to conventional mechanical ventilation plus exogenous surfactant replacement in rabbits

OBJECTIVES: (a) to evaluate the effect on oxygenation and ventilation of rabbits with induced surfactant depletion when they are submitted to a conventional mechanical ventilation, plus a small dose of exogenous surfactant; (b) to compare this group with another group submitted to a High Frequency Oscillation (HFO) without exogenous surfactant administration.METHODS: Twenty New Zealand White rabbits weighing (-/+ 3 kg) were anaesthetized and artificially induced to a endogenous surfactant depletion by successively lung lavage with normal saline (aliquots of 25 ml/kg) until to reach a persistent PaO(2) less than 100 mmHg when submitted to a mechanical ventilation in a pressure control mode with a target tidal volume of 10ml/kg, PEEP of 5cm H(2)O, FiO(2) 1.0, respiratory rate 30/min, and inspiratory time of 0.65 s. Then the rabbits were divided in (a) CMV+S group, submitted to a conventional mechanical ventilation plus exogenous surfactant replacement; (b) HFO group, submitted to a High Frequency Oscillation Ventilation. Arterial blood gases were measured at control period, post lung lavage, 15, 16 and 120 minutes after treatment started. The groups were compared using Student t test.RESULTS: The post lung lavage PaO(2) in both groups was lower than 50mmHg (p=0.154), increasing after 15 min of treatment to 254 mmHg (CMV+S) and 288 mmHg (HFO, p=0.626). The PaO(2) at 60 and 120 minutes were higher (p=0.001) in the HFO group (431 e 431 mmHg) when compared with the CMV+S group, which showed a progressive fall (148 e 126 mmHg). At 60 minutes of treatment, the PaCO(2) was lower (p=0.008) in the CMV+S group (29 versus 41 mmHg).CONCLUSIONS: In ARDS animal model a protect mechanical ventilation strategy as HFO by itself promotes a fast and persistent increase in the oxygenation, with superior levels than those observed in animals treated with conventional mechanical ventilation plus exogenous surfactant replacement.