Comparison of body surface and airway triggered ventilation in extremely premature infants

Failure of patient triggered ventilation in very premature infants may reflect the use of inappropriate triggering systems. We have therefore compared the performance of an airway and a body surface trigger in 12 infants of median gestational age 26 weeks (range 24–27). Airway flow and oesophageal and ventilator pressure changes were recorded during two periods of patient triggered ventilation. From the traces, the degree of asynchrony (inflation extending beyond inspiration), triggering rate, sensitivity (proportion of the infant's breaths detected) and trigger delay (response time) were calculated. Although with both triggering systems there was a high rate of asynchrony, the triggering rate ( p < 0.05), sensitivity ( p < 0.05) and trigger delay ( p < 0.01) were all better with the body surface trigger. These results suggest that the body surface trigger is the more appropriate system for very immature infants.     

Comparison of airway pressure and airflow triggering systems using a single type of neonatal ventilator

The performances of two triggering systems using a single neonatal ventilator type (SLE) were compared. Eight infants, gestational age 27-30 wk, were each recorded during two 1-h periods of patient-triggered ventilation (PTVs), one with airway pressure and one with airflow triggering. The airflow trigger had a shorter trigger delay (p < 0.02), higher sensitivity (p < 0.02) and lower asynchrony rate (p < 0.02). Conclusion: In immature infants with mild respiratory distress syndrome using the SLE ventilator with inflation times of 0.3 to 0.36 sec, airflow triggering is more appropriate than airway pressure triggering.     

Comparison of weaning by patient triggered ventilation or synchronous intermittent mandatory ventilation in preterm infants

Forty preterm infants were entered into a randomized controlled trial to compare the efficacy and duration of weaning by patient triggered ventilation (PTV) to that of synchronous intermittent mandatory ventilation (SIMV). Infants were randomized during recovery from respiratory distress once ventilator rate had been reduced to 40 breaths per minute; weaning during PTV was by reduction in ventilator pressure only, whereas infants randomized to SIMV were weaned by reduction in rate only. Weaning failed in 12 infants, 6 from each group, the 12 infants were more immature than those in whom weaning succeeded ( p < 0.01). Overall, the duration of weaning did not differ significantly between the PTV and SIMV groups.     

Long-term non-invasive positive airway pressure ventilation in infants

Aim: To evaluate the clinical application of long‐term non‐invasive ventilation (NIV) in infants with life‐threatening ventilatory failure with regard to: diagnosis, age at initiation, indication for and duration of treatment, clinical outcome and mortality and adverse effects. Patients and methods: The medical records of 18 infants treated in a home setting during a 7‐year period were reviewed. The criteria for ventilatory support were: (a) transcutaneous partial pressures of carbon dioxide (TcPCO₂) >6.5 kPa and oxygen (TcPO₂) < 8.5 kPa and (b) decreased cough ability and/or recurrent chest infections. Results: The median age at initiation was 4 months (range 1–12). NIV was initiated because of hypoventilation in 12 infants and because of reduced cough ability and/or recurrent infections in six infants. Tracheotomy was eventually needed in two infants. The median duration of treatment was 24 months (range 1–84). NIV produced significant improvements, with median TcPCO₂ falling from 9.9 to 6.1 kPa, and median TcPO₂ rising from 9.8 to 11.1 kPa. Conclusion: NIV can be successfully and safely used in infants with prolonged life‐threatening ventilatory failure, potentially avoiding intubation and tracheotomy.     

成比例辅助通气在呼吸机依赖极低出生体重儿中的临床应用

目的：比较成比例辅助通气模式（PAV）和传统辅/控通气模式（A/C）对呼吸机依赖极低出生体重儿的生理学和呼吸力学影响。方法：46例呼吸机依赖极低出生体重儿随机分为PAV组和A/C组（每组23例）。PAV组以脱逸法设置阻力卸载增益,A/C组按常规通气方法调节,连续通气治疗3 d。每日在早、中、晚3个时间段分别连续监测观察30 min,比较两组患儿动脉血气分析结果、血氧饱和度（SPO2）、心率、血压、呼吸频率（RR）、平均气道压（MAP）、吸气峰压（PIP）、呼吸末正压（PEEP）、潮气量（VT）、每分通气量（MV）及氧合指数（OI）等指标。结果：血气分析指标中,PAV组PaO2、OI高于A/C组（均P0.05）;呼吸力学指标中,PAV组PIP、MAP低于A/C组（均P0.05）;血流动力学指标中,PAV组收缩压、舒张压变异度均低于A/C组（均P0.05）。结论：对呼吸机依赖极低出生体重儿,较之A/C模式,PAV模式能以更低的气道压维持机体气体交换正常,改善氧合,人机协同性更好。     

Low colloid osmotic pressure in very low birthweight infants receiving assisted ventilation

Plasma colloid osmotic pressure (COP) was measured in three groups of very low birthweight infants. Babies in Group 1 ( n = 8) were breathing spontaneously and had no respiratory disease. Those in Group 2 ( n = 9) received assisted ventilation for hyaline membrane disease (HMD), and those in Group 3 ( n = 7) received assisted ventilation for other reasons (five apnoea, two pneumonia).
Both assisted ventilation groups had lower mean COP values than spontaneously breathing infants. Mean values (s.e.m.) for Groups 1,2 and 3, respectively, were: 15.3 (0.6), 11.3 (0.4) and 11.9 mmHg (0.5)( P < 0.001) on Day 1; and 15.2 (0.4), 12.9 (0.4) and 12.8 mmHg (0.3) ( P < 0.001) on Day 2. The Increase from Day 1 to Day 2 was significant for those with HMD ( P < 0.05). Colloid osmotic pressure correlated with mean blood pressure ( r = 0.51; P < 0.001) but not with birthweight, gestation, crystalloid fluid intake or pH.
The role of low COP in the pathogenesis of acute respiratory failure in infants with uncomplicated HMD is unclear, but such low COP may contribute to development of pulmonary oedema as a complication, particularly if the ductus'arteriosus is still patent and the infants are given high volume intravenous fluids.     

Inspiratory and expiratory times for infants ventilator-dependent beyond the first week

The aim of this study was to determine optimum inspiratory and expiratory times to be used for ventilation of infants older than one week of age. Each infant was studied at a rate of 30 breaths/min (inspiratory times (T_I) of 1.0, 0.67 and 0.5 s with expiratory times (T_E) of 1.0, 1.33 and 1.5 s, respectively) and at a rate of 60 breaths/min (T_I 0.5, 0.33 and 0.25 s and T_E 0.5, 0.67 and 0.75 s, respectively). Arterial blood-gases were examined after 20 min on each setting. Fifteen infants with a median gestational age of 27 weeks were studied at a median postnatal age of 9 days and 10 infants with a median gestational age of 27 weeks at a median postnatal age of 24 days. All infants had type I chronic lung disease. Oxygenation did not consistently improve as T_I was prolonged, elevating mean airway pressure but, particularly in older infants, was better at T_I± 0.5 s compared with T_I < 0.5 s. In both groups, carbon dioxide elimination was better at 60 than at 30 breaths/min. Thus we suggest that in infants fully ventilator-dependent beyond the first week of life, an inspiratory and expiratory time of 0.5 s should be used as the first choice.     

Bronchopulmonary dysplasia in very low birthweight infants

The incidence, clinical presentation and severity of bronchopulmonary dysplasia (BPD) in 110 consecutive very low birthweight (VLBW) infants admitted to the National University Hospital Neonatal Intensive Care Unit between October 1985 and January 1989 is reviewed. Thirty-two infants died, giving an overall survival rate of 70.9%. Sixty infants (54.4%) required mechanical ventilation in the first week of life; 24 (40%) of these infants died. Of the 36 survivors, 23 required oxygenation at 28 days of life and 21 fulfilled the criteria for BPD (35% of the 60 ventilated and 58% of the survivors). The incidence of BPD in all VLBW infants is 19% and of VLBW survivors 27%. Birthweight and gestational age appear to be important determinants. All the survivors in the 501-750 g birthweight group developed BPD compared to 6.25% in those above 1250 g. None of those greater than 30 weeks gestation developed BPD. Two forms of BPD were observed; the 'severe' group presented radiologically with chest radiographs characteristic of Stage IV BPD, while the 'mild' group with small or normal sized lungs demonstrated irregular strands of radio-densities alternating with areas of normal or increased lucency. The duration of mechanical ventilation and oxygen dependency were significantly longer in the 'severe' group, with the mean maximum peak inspiratory pressure, mean airway pressure, and FiO2 required in the first week of life being also significantly higher. Hyaline membrane disease was the main cause of respiratory failure requiring ventilation. The other causes were persistent pulmonary hypertension (1) and apnoea of prematurity (3); all of the latter developed only mild BPD.(ABSTRACT TRUNCATED AT 250 WORDS)     

"Idiopathic neutropenia'in very low birthweight infants

We employed a standardized investigative approach to evaluate four cases of"idiopathic neutropenia"in very low birthweight infants. The evaluation included maternal anti-neutrophil antibodies, a marrow aspiration, and a three-day trial of recombinant granulocyte colony-stimulating factor (rG-CSF). All patients had neutropenia at or shortly following delivery, and remained neutropenic (generally <500//μl) for 1-9 weeks until rG-CSF was administered. Blood and bone marrow studies in all 4 indicated that the neutropenia was: (i) the kinetic result of diminished neutrophil production; (ii) not alloimmune; (iii) not cyclic; and (iv) not associated with recognized inborn errors, bacterial or viral infections, or medications. All responded to rG-CSF by transiently increasing their blood neutrophils to normal, and the neutropenia resolved in all cases with time. It is likely that"idiopathic neutropenia"in this population represents a common phenotype of several different causes, rather than a single entity. Some cases, perhaps the majority, will respond to a short course of rG-CSF administration.     

Dopamine infusion and hypothyroxinaemia in very low birth weight preterm infants

The purpose of this study was to assess the relationship between transient hypothyroxinaemia of prematurity (THOP) in very low birth weight newborns and dopamine administration. A total of 172 newborns was enrolled in a prospective observational study and divided into three groups: group A included newborns who were never treated with dopamine; group B were infants in whom dopamine treatment was discontinued for at least 6 h before the congenital hypothyroidism screening and group C included infants who were given dopamine during the screening. Among those newborns given dopamine, the THOP incidence was higher (11.6% in group A; 53.8% in group B; 89.3% in group C), and the vales of TSH (1.67±2.32 µU/ml in group A; 1.29±1.74 µU/ml in group B; 0.89±1.34 µU/ml in group C) and thyroxine (6.1±2.2 µg/dl in group A; 3.9±1.9 µg/dl in group B; 2.4±1.4 µg/dl in group C) were significantly lower. These differences were further confirmed even after gestational age stratification and mathematical correction for differences in clinical conditions. The effects of dopamine appear to be dose-dependant. Conclusion:even if it cannot be excluded that reduced thyroid stimulating hormone and thyroxine concentrations are caused by non-thyroidal illness, the results suggest that the infusion of dopamine reduces the thyroid stimulating hormone and thyroxine levels in very low birth weight newborns.Abbreviations CHT congenital hypothyroidism - ESS euthyroid sick syndrome - GA gestational age - iRDS infantile respiratory distress syndrome - THOP transient hypothyroxinaemia of prematurity - VLBW very low birth weight     

Effect of body position on tidal volume and minute ventilation in very low birthweight infants

Background: To progress the clinical treatment of neonates, especially in the management of respiration, we have to be able to measure their pulmonary function appropriately. Various methods have been developed, but little is known about the pulmonary function of very low birthweight infants (VLBWI) because of the difficulty in taking their measurements with existing equipment. We have developed a very low dead space pneumotachograph to measure lung function in VLBWI. Methods and results: We used our pneumotachograph on 30 infants each weighing less than 1500 g at birth. The infants were intubated with endotracheal tubes of 2.5 or 2.0 mm diameter to measure tidal volume and minute ventilation in the prone and supine position. The tidal volume in the supine position was 6.99 ± 0.42 mL/kg and 7.58 ± 0.38 mL/kg in the prone position (mean ± SE). The tidal volume was significantly larger in the prone than the supine position (P < 0.05). However, no significant difference was observed in minute ventilation and respiratory rates. Conclusion: The tidal volume significantly increased in the prone position in VBLWI, confirming the previous observation of larger healthy infants is also applicable to the very low birthweight infants.     

极早产儿俯卧位机械通气对呼吸功能的影响

目的 探讨极早产儿俯卧位机械通气对呼吸功能的影响。方法 83例经口气管插管机械通气极早产儿随机分为仰卧位组和俯卧位组,4例退出研究,79例完成治疗和观察（仰卧位组37例,俯卧位组42例）,以容量辅助/控制模式机械通气。俯卧位组患儿每仰卧位通气4 h行俯卧位通气2 h。分组干预之前以及分组干预后仰卧位组每6 h、俯卧位组每于转换为俯卧位后的1 h,分别记录呼吸机参数、动脉血气分析和生命体征。结果 俯卧位组FiO₂、气道峰压,平均气道压、机械通气时间低于仰卧位组,差异有统计学意义（P < 0.05）;两组潮气量、呼气末正压的差异无统计学意义（P > 0.05）;俯卧位组的PO₂/FiO₂比值高于仰卧位组,而氧合指数、呼吸频率较低,差异均有统计学意义（P < 0.05）。两组PaO₂、pH、BE、心率和有创动脉血压平均压的差异无统计学意义（P > 0.05）。结论 俯卧位与仰卧位交替通气能改善机械通气极早产儿的氧合功能,降低吸入氧体积分数,缩短机械通气时间。     

不同通气模式对呼吸窘迫综合征极低出生体重儿心功能的影响

目的 探讨呼吸窘迫综合征（RDS）极低出生体重儿在不同机械通气模式下心功能的变化.方法 选择本院新生儿重症监护病房2009年1月至2012年12月收治的RDS极低出生体重儿为研究对象.根据随机号将患儿分为高频振荡通气组（HFOV）和常频机械通气组（CMV）两组.在通气8～12 h、生命体征相对稳定后,采用彩色多普勒超声对两组患儿心脏泵血功能进行评价,包括心输出量（CO）、左室射血分数（EF）、每搏输出量（SV）、收缩期主动脉瓣峰值流速（AV）、收缩期肺动脉瓣峰值流速（PV）、舒张期二尖瓣口峰值流速（MV）和舒张期三尖瓣口峰值流速（TV）.结果 研究期间共收治极低出生体重儿合并RDS者152例,89例符合入选标准,其中47例在研究过程中被排除,两组最终完成研究的例数均为21例.HFOV组胎龄（29.8±1.6）周,出生体重（1335±98）g;CMV组胎龄（28.7±1.8）周,出生体重（1344±115）g.两组胎龄、日龄、体重、心率、经皮血氧饱和度、血压、血气分析和RDS分度等方面差异均无统计学意义（P＞0.05）.HFOV组MAP高于CMV组[（9.5±1.2）cmH2O比（7.2±0.6） cmH2O,P＜0.05];心功能方面,HFOV组PV和MV均低于CMV组[（0.53±0.15） m/s比（0.66±0.18） m/s,（0.53±0.22） m/s比（0.71±0.07） m/s,P＜0.05],两组CO、EF、SV、AV及TV差异均无统计学意义（P＞0.05）.结论 HFOV组MAP增高,可降低右室收缩功能及左室舒张功能,但对左室收缩射血功能无明显影响.     

Prophylactic high-frequency oscillatory ventilation in preterm infants

The role of high-frequency oscillatory ventilation (HFOV) for the treatment of respiratory disease in preterm infants remains uncertain. Several randomized trials, comparing HFOV and conventional ventilation (CV) have been performed and their results suggest that HFOV may reduce the incidence of chronic lung disease (CLD) in preterm infants. However, the trials have several limitations and it remains unclear whether HFOV might increase intracranial pathology in very prematurely born infants. UKOS, a large, UK-based, multicentre trial was conducted to establish conclusively the role of prophylactic HFOV for the prevention of CLD in infants born prior to 29 wk of gestational age.
Conclusion : There is still a need to fully evaluate prophylactic HFOV with particular emphasis on both short and long term respiratory and neurological outcomes.     

Unstudied infants: outcomes of moderately premature infants in the neonatal intensive care unit

BACKGROUND: Newborns of 30-34 weeks gestation comprise 3.9% of all live births in the United States and 32% of all premature infants. They have been studied much less than very low birthweight infants. OBJECTIVE: To measure in-hospital outcomes and readmission within three months of discharge of moderately premature infants. DESIGN: Prospective cohort study including retrospective chart review and telephone interviews after discharge. SETTING: Ten birth hospitals in California and Massachusetts. PATIENTS: Surviving moderately premature infants born between October 2001 and February 2003. MAIN OUTCOME MEASURES: (a) Occurrence of assisted ventilation during the hospital stay after birth; (b) adverse in-hospital outcomes-for example, necrotising enterocolitis; (c) readmission within three months of discharge. RESULTS: With the use of prospective cluster sampling, 850 eligible infants and their families were identified, randomly selected, and enrolled. A total of 677 families completed a telephone interview three months after hospital discharge. During the birth stay, these babies experienced substantial morbidity: 45.7% experienced assisted ventilation, and 3.2% still required supplemental oxygen at 36 weeks. Readmission within three months occurred in 11.2% of the cohort and was higher among male infants and those with chronic lung disease. CONCLUSIONS: Moderately premature infants experience significant morbidity, as evidenced by high rates of assisted ventilation, use of oxygen at 36 weeks, and readmission. Such morbidity deserves more research.     

Nasal high-frequency ventilation for premature infants

Aim: To assess the use of nasal high‐frequency ventilation (HFV) to provide noninvasive ventilatory support for very low birthweight (VLBW) infants. Study Design: VLBW infants, >7 days of age on nasal continuous positive airway pressure (CPAP), were placed on nasal HFV for 2 h using the Infant Star high‐frequency ventilator (Mallinckrodt, Inc., St. Louis, MO, USA). Mean airway pressure was set to equal the previous level of CPAP, and amplitude was adjusted to obtain chest wall vibration. Capillary blood was sampled before starting HFV and after 2 h to determine change in pH and partial pressure of carbon dioxide (pCO₂). Results: Fourteen subjects were studied, 10 males and 4 females. Gestational age was 26–30 weeks (median 27). Age at study was 18–147 days (median 30). Median birth weight was 955 g; median weight at study was 1605 g. Nasal CPAP pressure was 4–7 cm H₂O (mean 5). Amplitude was 30–60 (median 50). After 2 h, PCO₂ (mean 45 torr) was significantly lower than initial PCO₂ (mean 50 torr) (p = 0.01), and pH had increased significantly (7.40 vs. 7.37, p = 0.04). Conclusions: Nasal HFV is effective in decreasing pCO₂ in stable premature infants requiring nasal CPAP support. Long‐term use of nasal HFV requires further study.     

Transfusion-associated fall in platelet count in very low birthweight infants

Abstract Thirty-three infants with a birthweight of less than 1500 g were investigated retrospectively for the incidence and aetiology of thrombocytopenia occurring during the first week of life. The platelet count fell below 100 × 10⁹/l in 16 infants (48%). There was a moderately strong inverse correlation between the platelet count at its nadir during the first week or the first value below 100 × 10⁹/l and the percentage of blood volume transfused prior to this ( r =−0.61; P < 0.0001). When the platelet count was expressed as a percentage of the initial count the correlation was −0.74 ( P < 0.0001). The results were not affected by the elimination of the 10 infants with clinical conditions regarded as a probable cause of thrombocytopenia. The fitted least-squares regression line suggests that a transfusion equal to 10% of the blood volume on average reduced the platelet count by 19 × 10⁹/l or by 7% in these very low birthweight infants during the first week of life.     

Comparison of three different noninvasive ventilation strategies as initial respiratory support in very low birth weight infants with respiratory distress syndrome: A retrospective study

BackgroundThere is inadequate evidence regarding which noninvasive ventilation (NIV) is superior for initial respiratory support of preterm infants with respiratory distress syndrome.ObjectivesTo compare the failure of noninvasive ventilation (NIV) and neonatal outcomes between nasal continuous positive airway pressure (NCPAP), bi-level positive airway pressure (BiPAP), and nasal intermittent positive pressure ventilation (NIPPV) as the initial respiratory support with less invasive surfactant administration (LISA) in very low birth weight (VLBW) infants.MethodsMedical records of 419 VLBW infants born at 26–30 weeks’ gestation who did not require intubation in the delivery room and were initially supported with either NCPAP (n = 221), BiPAP (n = 101), or NIPPV (n = 97) were retrospectively reviewed. The LISA approach was preferred in cases of surfactant requirement. The primary outcome was the failure of NIV within the first 72 h of life. Failure of NIV was defined as the persistence or recurrence of one or more of the following: hypoxemia, respiratory acidosis, more than one episode of apnea requiring bag and mask ventilation or more than six episodes of apnea requiring stimulation over a 6-h period. Data were analyzed using univariate and multivariate logistic regression analysis.ResultsFailure of NIV within the first 72 h of life was significantly higher in the NCPAP group (29.4%) compared with the BiPAP (12.9%) or NIPPV (12.4%) group (P < 0.001). However, the BiPAP and NIPPV groups were not different in terms of NIV failure (P = 0.91). Multivariable logistic regression analysis showed that antenatal steroid administration (OR: 0.49, 95% CI: 0.27–0.90; P = 0.02) and gestational age ˂ 28 weeks (OR: 2.03, 95% CI: 1.18–3.49; P = 0.01) were independent factors that influence failure of NIV within the first 72 h of life.ConclusionCompared with NCPAP, the use of NIPPV/BiPAP strategies for initial respiratory support can reduce the need for invasive ventilation in infants born at 26–30 weeks’ gestation.     

Morphine increases synchronous ventilation in preterm infants

Objectives: To examine the short-term cardiorespiratory effects of intravenous morphine infusion in ventilated preterm infants.
Methodology A randomized double-blind placebo-controlled trial in a neonatal intensive care unit. Twenty-six preterm infants (29-36 weeks gestation) with hyaline membrane disease requiring ventilatory assistance on the first day after birth were included in the study. A loading dose of morphine 100 μg/kg over 30 min followed by a continuous intravenous infusion at 10 μg/kg per hour was given. Primary measures were heart rate, blood pressure, respiratory rate and interaction of spontaneous respiration with mechanical ventilation. Secondary measures were durations of oxygen therapy, ventilator therapy and hospitalization as well as incidence of bronchopuimonary dysplasia, periventricular haemorrhage and pneumothorax.
Results Morphine-treated infants spent a significantly greater percentage of total ventilated time breathing in synchrony with their ventilators (median [IQ]= 72[58-87] vs 31 [17-51]%; P = 0.0008). Heart rate and respiratory rate, but not blood pressure, were reduced in morphine-treated infants. Duration of oxygen therapy was reduced (median [IQ]= 4.5[3-7] vs 8[4.75-12.5] days; P = 0.046).
Conclusions Intravenous morphine infusion increases synchronicity of spontaneous and ventilator-delivered breaths in preterm infants. Morphine reduces heart rate and respiratory rate without reducing blood pressure, and may help to reduce duration of oxygen therapy in preterm infants with hyaline membrane disease.     

Apnoea in very low birthweight infants: Outcome at 2 years

Follow-up data to 2 years are reported for 164 of an initial cohort of 172 consecutively, surviving very low birthweight infants. The 13 infants who suffered apnoeic episodes at home were not predicted at discharge from hospital. The mean (s.d.) general developmental quotient at 2 years for the total group was 97.3(12.0), compared with 99.0 (10.2) for the 72 infants who had nil-mild apnoea in the newborn period and 96.0 (13.4) for the 92 infants with moderate-severe apnoea ( P <0.1). All six infants with general quotients <76 had sustained moderate-severe apnoea ( P <0.05). Multivariate analysis to assess the influence of confounding variables showed that the presence of chronic lung disease decreased the general quotient by 4.0 units, birthweight <1000 g 3.3 units, mechanical ventilation 2.2 units and moderate-severe apnoea only 0.1 unit. Moderate-severe apnoea occurred in six of eight babies with neurological handicap and all eight with sensory handicaps ( P <0.01). Overall, of the 12 (7.3%) handicapped children, two had no apnoea and 10 moderate-severe apnoea ( P = 0.07).
Moderate or severe apnoea occurred in 58% of very low birthweight infants and was associated with the smallest and sickest infants who had the most handicaps at 2 years. However, when correction for birthweight <1000 g, mechanical ventilation and chronic lung disease is made, apnoea per se , as it was detected and managed between 1978-80, had no additional deleterious effect on average intellectual performance though it may have been an important causative factor in functional handicap.