Face mask resuscitation: does it lead to gastric distension?

Inflation and oesophageal pressures were recorded simultaneously during bag and mask resuscitation of 9 asphyxiated babies. After half a minute of standard inflation pressures, higher pressures were applied for at least 5 inflations by occluding the blow-off valve. No air entered the oesophagus until a high mean inflation pressure of 5.4 kPa was exceeded. These findings were confirmed in 4 fresh stillborn babies studied similarly. We conclude that resuscitation using bag and mask, applying pressures less than 3.5 kPa, should not lead to gastric distension.     

Use of permissive hypercapnia in the ventilation of infants with respiratory syncytial virus infection

We wished to retrospectively evaluate the effects of permissive hypercapnia (PHY) on barotrauma, mortality and length of stay when applied to ventilated infants with respiratory syncytial virus (RSV) bronchiolitis. Nineteen control infants with RSV induced respiratory failure were treated with conventional ventilation (April 1991–January 1994), after which time PHY was adopted as unit policy. A further 28 infants were then treated with PHY (January 1994–April 1996). Demographic and physiological data were collected from admission, and outcome variables including length of stay, barotrauma and mortality were recorded. The PHY group showed a significantly higher mean pCO₂ (7.6 vs 5.2 kPa), a lower mean pH (7.34 vs 7.40), and a reduction in maximal peak inspiratory pressures (25 vs 30 cmH₂O). Mortality, barotrauma, use of neuromuscular blockade and nosocomial infection did not differ between groups. There was a trend towards increased length of ventilation in the PHY group (median 7 vs 5 days). Conclusion Based on this retrospective data we can show no benefit for the use of permissive hypercapnia as a ventilatory strategy in this patient group. A prospective randomised controlled trial is warranted to accurately assess the outcome variables and cost implications of this strategy. Received: 22 June 1998 / Accepted in revised form: 25 August 1998     

Dry lung syndrome: complete airway collapse mimicking pulmonary hypoplasia?

We observed a premature baby born after severe oligohydramnios who could not be ventilated efficiently even with very high pressures immediately after birth, but who, after cessation of resuscitation attempts, recovered spontaneous sufficient breathing during the following hour. After this experience we searched our case records for other newborns with dry lung syndrome using the following definition: (1) premature birth after prolonged leakage of amniotic fluid, (2) very high ventilatory requirement after birth, (3) dramatic improvement during the first 24 to 36 h and (4) respiratory distress syndrome and infection excluded. Among 93 prematures with rupture of membranes for 4 days or more we found 3, including the index case, matching this definition. Conclusion Dry lung syndrome appears to be a distinct clinical entity that is possibly underrecognised but recognisable and that merits further study. Its pathogenesis may imply complete collapse of small airways to a degree that capillary forces impede distension by ordinary ventilatory pressures. Received: 18 December 1997 and in revised form: 9 March 1998 / Accepted: 13 March 1998     

Inflation times during resuscitation of preterm infants

Data on the effects of a prolonged inflation time during the resuscitation of very prematurely born infants are limited; one study showed no effect, and in another, although lower bronchopulmonary dysplasia (BPD) rates were seen, that effect could have been due to the prolonged inflation time, the positive end expiratory pressure applied or the combination of the two. The aims of our study were to assess the length of inflation times used during face mask and t-piece resuscitation of prematurely born infants in the labour suite and determine whether prolonged inflations led to longer inflation flow times. A respiration monitor (NM3 respiratory profile monitor) was used to record flow, airway pressure and tidal volume changes. The first five inflations for each baby were analysed. Forty prematurely born infants (median gestational age 30, range 26–32 weeks) were examined. Their median inflation pressure was 17.6 (range 12.2–27.4) cm H₂O, inflation time 0.89 (range 0.33–2.92) s, expiratory tidal volume 1.01 (range 0.02–11.41) ml/kg and inflation flow time 0.11 (range 0.04–0.54) s. There was no significant relationship between the inflation time and the inflation flow time, but there was a significant relationship between the inflation pressure and the inflation flow time (p = 0.024). Conclusion: These results suggest that prolonging inflation times during face mask resuscitation of prematurely born infants would not improve ventilation as prolonged inflation did not lead to longer inflation flow times.     

Appropriate positive end expiratory pressure level in surfactant-treated preterm infants

Positive end expiratory pressure (PEEP) is routinely used when ventilating preterm infants, and high levels are recommended in those with severe respiratory distress syndrome (RDS). Elevation of PEEP increases lung volume, as does surfactant administration. We postulated that in surfactant-treated infants even modest PEEP levels could result in overdistension and (CO₂) retention. To test that hypothesis, lung volume, compliance and arterial blood gases were measured in eight preterm infants (median gestational age 28 weeks, range 26–35 weeks) at three PEEP levels. The infants, all with RDS, were studied at a median time of 18 h, (range 12–68 h) after their last dose of surfactant. Infants were routinely nursed at 3 cmH₂O of PEEP, the PEEP level was then raised to 6 cmH₂O or lowered to 0 cmH₂O in random order. The new setting was maintained for 20 min; the PEEP level was then changed to the third level (0 or 6 cmH₂O) again for 20 min. At the end of each 20-min period, lung volume, compliance and blood gases were measured. Lung volume was assessed by measuring functional residual capacity (FRC) using a helium dilution technique. Compliance was measured by relating the volume change from a positive pressure inflation maintained until no further volume change occurred to the pressure drop (peak inflating pressure PEEP). Increasing PEEP from 0 to 3 cmH₂O and particularly to 6 cmH₂O resulted in increases in FRC (P < 0.05), oxygenation (ns) and paCO₂ (P < 0.02). Specific compliance (compliance/FRC) (P < 0.05) and pH (P < 0.02) fell. Conclusion Following surfactant treatment, relatively low levels of positive end expiratory pressure (≤3 cmH₂O) may be appropriate. Received: 20 April 1999 / Accepted: 26 May 1999     

Lung expansion, tidal exchange, and formation of the functional residual capacity during resuscitation of asphyxiated neonates.

Ventilatory exchange and endotracheal and esophageal pressures were measured during resuscitation of asphyxiated neonates born by cesarean section. In contrast to spontaneously breathing, vaginally born babies, an opening pressure had to be exceeded before lung expansion occurred. Subsequently there was usually a gradual increase in gaseous exchange over the first few lung inflations. A further rise in lung compliance occurred with the baby's inspiratory efforts. The functional residual capacity was formed with or without active inspiratory efforts by the baby, although gaseous retention occurred more rapidly as a result of the infant's inspiration.     

The importance of ventilation to effective resuscitation in the term and preterm infant

Although resuscitation at birth often has a successful outcome, there is very little data available on the optimal method. Face mask/bag resuscitation is relatively ineffective, rarely producing adequate alveolar ventilation before lung expansion has occurred, probably depending on the Head's Paradoxical Reflex to stimulate inspiratory efforts The T-piece/face mask technique is easier to use and more effective as the inflation pressure can be maintained for longer. Standard T-piece/endotracheal tube resuscitation produces inflation volumes of less than half of those generated by spontaneously breathing infants, and the functional residual capacity is not formed for several breaths. This can be overcome by maintaining the first inflation for 3 s. More studies are urgently required in very preterm infants as these are particularly vulnerable to volutrauma immediately after delivery.     

Pneumomediastinum in newborns induced by the Elder CPR/demand valve during resuscitation

Two term and one post-term newborn infants with pneumomediastinum associated with the use of an Elder CPR (cardiopulmonary resuscitation)/demand valve during resuscitation are described. Because of apnea or irregular gasping respiration after vaginal delivery, they received repetitive positive-pressure ventilation with this resuscitator, which is designed to provide 100% oxygen with a limited pressure of up to 40 cmH₂O. Following resuscitation, the infants had tachypnea and diminished breath sounds. Roentgenograms and computed tomography of the chest revealed pneumomediastinum in all three and cervical subcutaneous emphysema in one. They required 25–30% oxygen for 3–14 days until they recovered spontaneously. Thus, pressures as low as 40 cmH₂O can cause barotrauma, and the Elder resuscitator, even when functioning properly, may injure the lungs of newborn infants.     

Does sustained lung inflation at resuscitation reduce lung injury in the preterm infant?

BACKGROUND: Bronchopulmonary dysplasia (BPD) is a common outcome of preterm birth. Experimental animal work has shown that initial ventilation strategies injure the immature lung and may lead to BPD. Studies with asphyxiated babies have shown that, if tidal ventilation at birth is preceded by sustained lung inflation, larger inflation volumes can be achieved, which is thought to lead to clearance of lung fluid and formation of the functional residual capacity (FRC). OBJECTIVE: To see if sustained lung inflation at initial resuscitation of preterm babies would facilitate the removal of lung fluid, establish the FRC, and allow an even distribution of alveolar opening, permitting less aggressive ventilation, leading to a reduction in pulmonary inflammation and subsequent BPD. METHOD: The outcomes of 52 babies of less than 31 weeks gestation, resuscitated at birth using either a sustained lung inflation of five seconds or a conventional lung inflation of two seconds for the first assisted breath of resuscitation, were examined. Evidence of pulmonary inflammation was determined by quantification of interleukins 6, 10, and 1beta and tumour necrosis factor alpha in bronchoalveolar lavage fluid by enzyme linked immunosorbent assay. RESULTS: There were no significant differences in any of the cytokines. Death occurred in 3/26 babies in the conventional group and 6/26 babies in the sustained lung inflation group. Survival without BPD occurred in 13/26 and 14/26 respectively. CONCLUSION: The use of sustained lung inflation at resuscitation did not reduce lung injury, as measured by inflammatory markers.     

Persistent pulmonary arterial hypertension of the new born

Persistent pulmonary hypertension of the newborn (PPHN) characterised by right to left shunting with intense cyanosis is difficult to manage, and in the best of centres carries a 40–60 percent mortality. We report our one year's experience of managing six neonates with PPHN. There were 5 males and 1 female with mean birth weight of 2.59±0.487 kg and gestation period 39±2.0 wks and 1 minute Apgar score 2.8±2.1. Four to six babies were born by cesarean section and 3–6 babies had aspiration pneumonia. All babies presented within 12 hours of age (mean 5.08±5 hrs) with intense cyanosis and respiratory distress. Diagnosis were confirmed in all by (a) hyperoxia test, (b) simultaneous determination of preductal and postductal paO₂ (c) contrast echocardiography and (d) hyperoxia-hyperventilation test. Babies were managed with hyperventilation using mean ventilatory rates of 100±45 per minute, an inspired oxygen concentration of 100%, peak inspiratory pressures 27±9 cm of H₂O, and expiratory pressures 5±1.6 cms of H₂O, and mean air way pressures of 10.4±2.7 cms H₂O. Alkali therapy was used in 3 of the six babies whereas low dose dopamine was infused in all six babies. Inspite of aggressive ventilatory therapy, only 3 out of 6 babies could be salvaged.     

Inhaled salbutamol and beclomethasone for preventing broncho-pulmonary dysplasia: a randomised double-blind study

Early inflammatory lesions and bronchial hyperresponsiveness are characteristics of the respiratory distress in premature neonates and are susceptible to aggravation by assisted ventilation. We hypothesized that treatment with inhaled salbutamol and beclomethasone might be of clinical value in the prevention of bronchopulmonary dysplasia (BPD) in ventilator-dependent premature neonates. The study was double-blinded and placebo controlled. We studied 173 infants of less than 31 weeks of gestational age, who needed ventilatory support at the 10th postnatal day. They were randomised to four groups and received either placebo + placebo, placebo + salbutamol, placebo + beclomethasone or beclomethasone + salbutomol, respectively for 28 days. The major criteria for efficacy were: diagnosis of BPD (with score of severity), mortality, duration of ventilatory support and oxygen therapy. The trial groups were similar with respect to age at entry (9.8–10.1 days), gestational age (27.6–27.8 weeks), birth weight and oxygen dependence. We did not observe any significant effect of treatment on survival, diagnosis and severity of BPD, duration of ventilatory support or oxygen therapy. For instance, the odds-ratio (95% confidence interval) for severe or moderate BPD were 1.04 (0.52–2.06) for inhaled beclomethasone and 1.54 (0.78–3.05) for inhaled salbutamol. Conclusion This randomised prospective trial does not support the use of treatment with inhaled beclomethasone, salbutamol or their combination in the prevention of BPD in premature ventilated neonates. Received: 20 November 1997 / Accepted: 2 March 1998     

Physiological responses of the newborn infant to resuscitation.

Lung ventilation, endotracheal, and intraoesophageal pressures were measured during standard resuscitation of 20 asphyxiated babies born by caesarean section. The most common response to resuscitation was the production of a large positive intraoesphageal pressure. An opening pressure greater than 2.0 kPa was required to expand the lungs of most of these babies. The need for resuscitation was associated with prolonged maternal anaesthesia before delivery.     

The effects of synthetic and natural surfactant on fluid balance in acute respiratory distress syndrome

To evaluate the effect of different surfactants on fluid balance in respiratory distress syndrome, we studied 24 premature infants who were randomised to receive either natural or synthetic surfactant. Data were collected on ventilatory parameters, daily urine output, daily weight, fluid intake and serum electrolytes. Ventilatory requirements decreased more rapidly in babies receiving natural surfactant, with significantly greater reductions in mean airway pressure from 1 to 48 h and oxygenation index from 1–18 h (P < 0.05). There were no differences in fluid intake and serum electrolytes. Mean daily urine output was higher in the group receiving natural surfactant (87 ml versus 61 ml, P < 0.05). This group also had a greater weight loss from birth weight (−146 g versus −65 g, P < 0.05). Conclusion Natural surfactant produces an earlier reduction in ventilatory requirements with an earlier diuresis. This should influence fluid management in respiratory distress syndrome. Received: 10 February 2000 / Accepted: 24 April 2000     

Airway Pressure Release Ventilation: An Alternative Ventilation Mode for Pediatric Acute Hypoxemic Respiratory Failure

Airway pressure release ventilation (APRV) is a relatively new mode of mechanical ventilation. The use of this model of ventilation in pediatrics has been limited. The authors describe their experience with this mode of ventilation in a series of pediatric hypoxemic respiratory failure patients. Three patients with acute hypoxemic respiratory failure (AHRF) were treated with APRV, when oxygenation did not improve with pressure control ventilation (PCV). The mean age of the patients was 5.8 ± 1.3 months. Fractional oxygen concentration decreased from 0.97 ± 0.02 for PCV to 0.68 ± 0.12 for APRV, peak airway pressure fell from 36.6 ± 11.5 cm H₂O for PCV to 33.3 ± 5.7 cm H₂O for APRV, mean airway pressure increased from 17.9 ± 5.9 cmH₂O for PCV to 27 ± 2.6 cmH₂O for APRV and release tidal volume increased from 8.3 ± 1.5 mL/kg for PCV to 13.2 ± 1.1 mL/kg for APRV after 1 h. APRV may improve oxygenation in pediatric AHRF when conventional mechanical ventilation fails. The APRV modality may provide better oxygenation with lower peak airway pressure.     

Resuscitation of newborn infants with room air or oxygen

Oxygen is a toxic agent and a critical approach regarding its use during resuscitation at birth is developing. Animal data indicate that room air is efficient for newborn resuscitation. Three clinical studies have established that normal ventilation is delayed after oxygen resuscitation. Oxidative stress is augmented for several weeks in infants exposed to oxygen at birth – the long-term implications of these observations remain unclear. There are limited data regarding the use of room air during complicated resuscitations, i.e. in meconium aspiration, the severely asphyxiated infant and in the preterm infant. Thus, it is necessary to continue ongoing rigorous examination of the long-accepted practice of oxygen administration during neonatal resuscitation.     

Growth hormone treatment increases CO2 response, ventilation and central inspiratory drive in children with Prader-Willi syndrome

We studied whether the beneficial effects of growth hormone (GH) treatment on growth and body composition in PWS are accompanied by an improvement in respiratory function. We measured resting ventilation, airway occlusion pressure (P_0.1) and ventilatory response to CO₂ in nine children, aged 7–14 years, before and 6–9 months after the start of GH treatment. During GH treatment, resting ventilation increased by 26%, P_0.1 by 72% and the response to CO₂ by 65% (P < 0.002, <0.04 and <0.02, respectively). This observed increase in ventilatory output was not correlated to changes in body mass index. Conclusion Treatment of children with Prader-Willi syndrome (PWS) seems to have a stimulatory effect on central respiratory structures. The observed increase in ventilation and inspiratory drive may contribute to the improved activity level reported by parents of PWS children during growth hormone therapy. Received: 28 April 1998 / Accepted: 6 April 1999     

Simple method of <100% oxygen resuscitation for preterm infants

Background: The aim of this study was to determine the feasibility of 50–60% oxygen resuscitation by a simple method using a self‐inflation bag without oxygen reservoir for positive pressure ventilation (PPV) or using a constant distance and flow rate for blow‐by oxygen. Methods: Newborn infants ≤35 weeks gestational age were eligible. Infants requiring PPV were initiated with bag‐mask PPV without oxygen reservoir. Nearly 100% oxygen was given by attaching oxygen reservoir if heart rate < 100 beats/min after PPV for 90 s or SpO₂ < 75% at 3 min. For those requiring blow‐by oxygen, oxygen flow 5 L/min via facemask was given 5 cm from the nose. Almost 100% oxygen was given by close‐fitting facemask to nose if SpO₂ < 80% at 5 min. Results: Ninety‐one infants were eligible; 67 of them required resuscitation. Thirty‐five infants required PPV; 27 (77.1%) responded to bag‐mask PPV without oxygen reservoir. For 32 infants requiring blow‐by oxygen, 28 (87.5%) reached the targeted SpO₂. No significant differences in clinical outcomes were observed between responders and non‐responders. Conclusions: The technique of <100% oxygen supplementation was effective for preterm newborn resuscitation with a high success rate. This technique may be useful for a limited‐resource setting.     

Response to bronchodilators in clinically stable 1-year-old patients with bronchopulmonary dysplasia

Bronchodilators are often used in the treatment of patients with bronchopulmonary dysplasia (BPD). However, few studies evaluate their efficacy in patients with stable disease beyond the newborn period. Therefore, pulmonary function was measured before and after aerosol treatment with salbutamol (0.25 ml Ventolin 0.5%) and subsequently after aerosol with ipratropium bromide (0.25 ml Atrovent 0.025%). Studies were performed at the corrected postnatal age of 52±2 weeks in 52 patients who had been ventilated after birth because of newborn lung disease. Twenty-two of these 52 patients had developed BPD. Pulmonary function was measured after sedation and using the PEDS system. Expiratory resistance (median 52.1 versus 39.1 cmH₂O/l/s; P<.008) and inspiratory resistance (median 42.5 vs 27.8 cmH₂O/l/s; P<.04) were significantly worse in BPD patients at the age of 1 year. Half of the BPD patients had a decrease in pulmonary resistance after salbutamol. However, there was no statistically significant decrease in pulmonary resistance after salbutamol or ipratropium in the BPD patients as a group. After salbutamol pulmonary resistance significantly worsened in the patients who did not develop BPD. Conclusion Although individual patients may benefit, routine administration of bron chodilators seems not warranted in stable BPD patients at the age of 1 year. Received: 14 February 1997 / Accepted in revised form: 14 July 1997     

Ventilator assessment of respiratory mechanics in paediatric intensive care

Many modern “paediatric” mechanical ventilators have in-built features for estimation of respiratory mechanics which could be useful in the management of ventilated infants and children. The aim of this study was to determine if such measurements were reproducible and accurate. Ventilator (Draeger Evita 4) displayed compliance (Cvent) and resistance (Rvent) values were assessed and compared to the results of respiratory system mechanics (respiratory system compliance (Crs) and resistance (Rrs)) measurements obtained using a single breath occlusion technique. Seventeen children (median age 5.1; range 0.3 to 16 yrs) were studied on 24 occasions. The mean coefficients of variations for the techniques were similar (Cvent 13%; Crs 11%; Rvent 16%; Rrs 14%). The mean (SD) Crs (22.8 (12.3) ml/cmH₂O) did not differ significantly from Cvent (22.1 (12.7) ml/cm H₂O) but the mean Rrs 21.0 (12.7) cmH₂O/l/s was significantly higher than the mean Rvent 32.0 (32.0) cmH₂O/l/s (p = 0.03). Bland and Altman analysis demonstrated a mean difference of −10.94 cmH₂O/l/s (SD 24.1) between Rrs and Rvent; the agreement between Rrs and Rvent decreased as Rrs increased (p = 0.008). Conclusions: Ventilator assessment of compliance, but not resistance, using the Evita 4 is reproducible and reliable. Funding note: Dr Harikumar was supported by the Wellcome Trust.     

Cardiopulmonary interaction during partial liquid ventilation in surfactant-treated preterm lambs

Gas ventilation following instillation of perfluorochemical (PFC) liquid, partial liquid ventilation (PLV), improves gas exchange and pulmonary mechanics in neonatal animals and humans with severe respiratory distress. The effect of PLV on cardiac contractility, performance, pulmonary blood flow and ductal shunt has not been fully described. To this end, we evaluated these indices of cardiopulmonary function in eight conventionally gas ventilated, surfactant-treated premature lambs (125 days gestation) before and during PLV. Animals were instrumented with central venous and aortic lines. Serial evaluation of arterial blood chemistry/pressure, and pulmonary mechanics was performed; cardiac contractility, performance, pulmonary blood flow and ductal shunts were serially assessed by echocardiography. As compared to conventional gas ventilation, during PLV there was a significant decrease in left ventricular meridian (22.5 ± 6.6 SE vs 8.1 ± 1.4 SE g/cm², P < 0.02) and circumferential wall stress (54.1 ± 16.5 vs 24.4 ± 3.8 SE g/cm², P < 0.04) at end systole. The fall in wall stress at end systole was associated with a significant decrease in left ventricular internal diameter (1.2 ± 0.05 SE vs 1.04 ± 0.045 SE cm; P < 0.01). There were no significant changes in heart rate, systemic arterial and central venous pressures, systemic vascular resistance, left ventricular shortening and ejection fractions during PLV. The decrease in wall stress was associated with a significant decrease in mean airway pressures (15.9 ± 1.1 SE vs 9.9 ± 0.2 SE cmH₂O; P < 0.05) and ostensibly a change in intrathoracic pressures during PLV. There were no significant differences in blood flows (pre vs during PLV; ml/min/kg): pulmonary (226 ± 62 SE vs 293 ± 65 SE), aortic (237 ± 36 SE vs 204 ± 21 SE), and left to right ductal (119 ± 25 SE vs 105.5 ± 26 SE) measured before and during PLV. Conclusion Cardiac output and pulmonary blood flow do not change significantly during PLV and therefore do not appear to contribute to improved gas exchange. This stable cardiac performance occurs at lower wall stress and thereby more advantageous energetic conditions. Received: 18 July 1996 and in revised form: 28 May 1997 / Accepted: 31 May 1997