Table 1
Clinical trials and physiological studies of continuous distending pressures
| Year | Trials | Results |
|---|---|---|
| 1971 | Gregory et al 19 | First use of CPAP in neonates showed oxygenation increased by 38% within 12 hours and survival improved. |
| 1973 | Rhodes and Hall20 | Randomised infants to face mask CPAP or control. Mortality was 53% in controls and 27% with CPAP. |
| 1973 | Kattwinkel et al 21 22 | Showed that CPAP significantly reduces the duration of exposure to high levels of oxygen. |
| 1973 | Herman and Reynolds23 | Showed that oxygenation increased as PEEP increased from 0 to 5 cm H2O with no extra improvement at 10 cm H2O. Arterial PaCO2 increased as the PEEP increased but at 10 cm H2O the PaCO2 was “unacceptably high”. |
| 1976 | Berman et al 24 | Intubated infants recovering from RDS had the lowest oxygenation and lung volume with zero PEEP. They improved when the infants received a PEEP of 2 cm H2O or were extubated. |
| 1976 | Speidal et al 25 | Nasal CPAP regularised the respiratory pattern and abolished or reduced apnoeic attacks. |
| 1979 | Alexanderet al 26 | Nasal CPAP and continuous negative pressure both improved oxygenation. Nasal CPAP was easier. Both techniques produce some air leaks. |
| 1981 | Stewartet al 27 | Increases in PEEP improved oxygenation per cm H2O mean airway pressure than increasing peak inspiratory pressure or changing the I:E ratio. Increasing PEEP increased the PaCO2. |
| 1982 | Engelkeet al 28 | Nasal CPAP post extubation compared with head box oxygen showed that nasal CPAP improved oxygenation, carbon dioxide levels, pH, chest x-rays and lowered the respiratory rate. |
| 1986 | Kim et al 29 | Endotracheal tube CPAP for six hours reduced extubation success compared with extubation to a head box. |
| 1987 | Hausdorf et al 30 | Increasing PEEP proportionally reduced the left and right ventricular stroke volume and cardiac output and slightly impaired the systemic and pulmonary blood flows. |
| 1988 | Trang et al 31 | Cardiac index fell at PEEP of 3, 6, 9 cm H2O by 6%, 11% and 19%. The stiffer the lungs the smaller the effect. Despite this, heart rate and mean blood pressure did not change. |
| 1991 | Higgins et al 32 | In a randomised trial of extubation strategies for babies <1 kg: 75% were successfully extubated when treated with nasal CPAP and only 30% if treated in a head box. |
| 1992 | Greenough et al 33 | Acutely ventilated infants increased oxygenation and carbon dioxide as PEEP levels increased. Chronically ventilated infants showed the same trends for oxygen but with little effect on PaCO2. |
| 1993 | Chan et al 34 | Compared extubation to head-box oxygen or nasal CPAP at 3 cm H2O and showed no difference in failure rate between the two. |
| 1994 | Da Silva et al 35 | Increasing PEEP from 2 to 5 cm H2O increased the FRC from 18.4 ml/kg to 22.6 ml/kg (about 20 to 30 ml/kg in healthy neonates). Increasing PEEP by 1 cm H2O increased the FRC on average by 1.3 ml/kg. |
| 1994 | Bartholomew et al 36 | A 1 cm H2O change in PEEP had twice the effect on tidal volume as a 2 cm H2O change in peak pressure in paralysed infants. Reductions in PEEP are as effective at reducing PaCO2 as increasing the peak inspiratory pressure. |
| 1995 | Tapia et al 37 | Showed no clear effect of extubating babies to nasal CPAP compared with head-box oxygen at 3 to 4 cm H2O. |
| 1995 | So et al 38 | Reintubation occurred in 16% of infants treated with CPAP compared with 52% treated in a head box. |
| 1998 | Davis et al 39 | Different levels of CPAP applied to infants with tracheomalacia increased the lung volume but did not alter the forced expiratory flow. |
| 1998 | Ahluwalia et al 40 | In a cross over study showed there was no difference in oxygenation, other physiological parameters or comfort score between single prong nasal CPAP and the Infant Flow Driver. |
| 1998 | Davis et al 41 | This study randomised extubated babies to nasal CPAP or head box and showed that 66% were successfully extubated to CPAP and 40% to head box. Nasal CPAP after extubation reduces the adverse events without increasing side effects. |
| 1998 | Robertsonet al 42 | Ventilated premature babies were randomised at extubation to nasal CPAP or head box oxygen although the head box group also received CPAP if criteria were met. There was no difference in successful extubation between the groups. Therefore CPAP may be used for prophylaxis or rescue treatment at extubation. |
