An Evaluation of Bubble-CPAP in a Neonatal Unit in a Developing Country: Effective Respiratory Support That Can Be Applied By Nurses

Abstract

To describe the implementation of bubble-CPAP in a referral hospital in a developing country and to investigate: the feasibility of nurses implementing bubble-CPAP and the impact of bubble-CPAP on need for mechanical ventilation and mortality. Retrospective evaluation of prospectively collected data from two time periods: 18 months before and 18 months after the introduction of bubble-CPAP. The introduction of bubble-CPAP was associated with a 50 per cent reduction in the need for mechanical ventilation; from 113 of 1106 (10.2 per cent) prior to bubble-CPAP to 70 of 1382 (5.1%) after introduction of CPAP (χ², p<0.001). In the 18 months prior to bubble-CPAP there were 79 deaths (case fatality of 7.1 per cent). In the 18 months after bubble-CPAP there were 74 deaths (CF 5.4 per cent), relative risk: 0.75 (0.55–1.02, χ², p=0.065). Nurses could safely apply bubble-CPAP after 1–2 months of on-the-job training. Equipment for Bubble-CPAP cost 15 per cent of the cost of the cheapest mechanical ventilator. The introduction of bubble-CPAP substantially reduced the need for mechanical ventilation, with no difference in mortality. In models of neonatal care for resource-limited countries, bubble-CPAP may be the first type of ventilatory support that is recommended. Its low cost and safety when administered by nurses makes it ideal for this purpose. Bubble-CPAP has the potential for being available at even lower cost than the current commercially available bubble systems used in this study.

Introduction

In developing countries, the introduction of Western models of neonatal intensive care has implications for the equitable distribution and cost of health care resources. Additional costs include those required for establishment and maintenance of technology, and wages for adequate numbers of staff and the cost of training. In Western countries the backbone of neonatal intensive care has been mechanical ventilation, which, in addition to high cost, is associated with technical complications where human and financial resources are stretched. When developing and transitional countries have reached the stage where basic neonatal care is in place, a model of how to set up appropriate referral-level neonatal care is necessary.

CPAP has become a common form of support for respiratory distress in neonatal intensive care units in industrialized countries. However CPAP is most frequently delivered to neonates using conventional mechanical ventilators; thus there is minimal or no cost saving. Bubble-CPAP has been available since the 1970s, but the earliest report is from 1992, which describes in vitro testing and use in three low birth weight neonates [1]. Bubble-CPAP involves a source of gas flow (typically 6–8 L per minute in a neonate), an air-oxygen blender, humidifier, and a T-piece, the expiratory arm of which is inserted in a bottle of water. The CPAP level delivered is equivalent to the distance that the distal end of the expiratory tubing is under water. Robust equipment is now available at a fraction of the cost of mechanical ventilators. Bubble-CPAP has several potential advantages over mechanical ventilation: lower cost, application by nursing staff, and lower risk of complications, and has been proposed as an inexpensive method of delivering CPAP in developing countries [2]. However, as there are few published reports of bubble-CPAP in developing countries, we evaluated the introduction of the technique in a government hospital neonatal intensive care unit (NICU) in Fiji. We investigated whether there were any differences in neonatal case fatality rates before and after the introduction of bubble-CPAP.

The site

Fiji has a population of 775 077, with 18 350 births annually. 54 per cent of the population is rural dwelling. The infant and child mortality rates are 17 and 24 per 1000 live births, respectively. Throughout the country access to antenatal care is generally good; 98 per cent of mothers deliver in a health facility. Referral systems are also generally good, with a medical or nursing escort for sick newborns and children transferred by aeroplane or boat from outlying islands. All health care, including transport, is free, and funded by the Fiji Government. Health centres and nursing stations are widely distributed in the rural areas. Deaths of children at home without accessing health care are very rare. The Colonial War Memorial Hospital is the referral hospital for the eastern side of the island of Viti Levu and the entire Eastern region, and the only hospital that provides neonatal intensive care services. The NICU admits about 60–75 neonates per month.

Methods

Data collection and evaluation

We studied all neonates admitted to the NICU 18 months before and 18 months after the introduction of bubble-CPAP in May 2003. Data on all babies who are admitted to the NICU were collected prospectively by the nurse-in-charge. We studied, in detail, the records of all babies requiring any form of respiratory support (oxygen, mechanical ventilation or bubble-CPAP). The following data were extracted: birth or admission weight, gestational age, diagnoses, presence of positive bacterial cultures at any time during the admission, duration of hospital stay and outcome.

Data were entered into an Excel spread sheet and analysed with Stata 7.0 (Statacorporation, Texas). Differences in mortality between the two time periods were analysed using the χ² test, and presented as relative risk and 95 per cent confidence intervals (95 per cent CI). Student's t-test was used for comparison of means of continuous variables with normal distribution. The Mann-Whitney U test to compare variables with marked skewness of distribution.

The study was approved by the administration of the Colonial War Memorial Hospital.

Results

Equipment and training

Before May 2003, nurses were only able to provide oxygen to neonates who had respiratory distress or apnoea, as they were not trained in insertion of nasopharyngeal tubes or anaesthetic techniques. For 6 years before the introduction of bubble-CPAP, the NICU had 5 ventilators: 3 Bearcub, cost of $40,000 each; and 2 Servo3000, cost of $65 000 each. In May 2003, bubble-CPAP was introduced. Equipment was purchased to provide bubble-CPAP to two neonates at any one time. The costs were $6000 for each blender and humidifier (Fisher & Paykel Pty Ltd), and $300 for circuitry. All equipment was donated by JICA (The Japanese Government Aid Organization), but the Fijian Ministry of Health is responsible for ongoing costs, and for expansion of appropriate neonatal services in other government hospitals.

In May 2003, three senior nurses/midwives were trained to recognize babies in respiratory distress and how to safely apply the nasal prongs and set up the CPAP circuit. Nurses from Australia conducted a three-day workshop at CWMH on the use of CPAP. Training of additional nurses was undertaken on the job, requiring one or two months before a nurse was considered competent to commence bubble-CPAP. A nurse trained in CPAP was rostered for each shift, and the nurse-patient ratio is 1:3 at best. Nurses frequently commenced CPAP during the initial observation period after arrival in the NICU. Indications for CPAP included grunting, severe chest indrawing, severe respiratory distress, and haemoglobin oxygen saturation <90 per cent despite oxygen delivered by head box or nasal catheter.

Patients

Tables 1 and 2 describe the characteristics and diagnoses present in these neonates requiring any form of respiratory support (oxygen, CPAP or mechanical ventilation) in the two eras. During the first and second time periods 1106 and 1382 neonates, respectively were admitted. The neonates admitted during the two time periods were similar in weight, age of admission (median and IQR in the first day of life in both eras), but there were a higher proportion of babies weighing 1000–1500 g in the first time period (p = 0.008).

Requirement for respiratory support

Some form of respiratory support (oxygen, CPAP or mechanical ventilation) was required by 596 (53.8 per cent) and 556 (40.2 per cent) neonates in the respective periods (Table 3). The introduction of bubble-CPAP was associated with a 50 per cent reduction in the need for mechanical ventilation. In the first time period mechanical ventilation was required by 113 neonates (10.2 per cent of all newborns admitted); after bubble-CPAP became available only 70 (5.1 per cent) required mechanical ventilation at any stage in their admission (χ²p < 0.001). In a logistic regression analysis that includes weight (the major observed difference at baseline in the two populations) as a variable, the odds ratio for requiring mechanical ventilation was 1.5 (95 per cent confidence intervals 1.2–2.1) prior to the introduction of bubble-CPAP.

Of the 105 who received CPAP, 24 failed and required mechanical ventilation, while 6 received bubble-CPAP as part of weaning from mechanical ventilation.

Effect on mortality

There was no difference in mortality between the two time periods. Among the 1106 neonates admitted between September 1st 2001 and May 14th 2003 there were 79 deaths (case fatality of 7.1 per cent). Among the 1382 neonates admitted between May 15th 2003 and August 30th, 2004 there were 74 deaths (CF 5.4 per cent), relative risk: 0.75 (0.55–1.02, χ², p = 0.065 (Table 3). In a logistic regression analysis that included weight as a variable, there was no difference in mortality between the two eras (odds ratio 1.04; 95 per cent confidence intervals 0.72–1.5).

Discussion

This was an observational study of the introduction of a new technique for ventilatory support for neonates with respiratory distress, in a referral hospital in a developing country. Bubble-CPAP was feasible and safe in this hospital that had nurse-patient ratios less than normally required by intensive care units, and one medical registrar, who out-of-hours had to cover all paediatric areas of the hospital (children's ward, emergency department, labour ward, paediatric intensive care unit and NICU). Nurses could safely apply bubble-CPAP after 1–2 months of on-the-job training. In this study there was no difference in mortality when neonates with respiratory distress were predominantly managed with intubation and mechanical ventilation or managed predominantly with bubble-CPAP, and the need for mechanical ventilation was 50 per cent lower after introduction of bubble-CPAP.

Some caution is required in the interpretation of these results. This was not a randomized trial, and other factors confounding mortality rates are possible. There were some differences in the two populations we compared. There was a significantly higher proportion of neonates with very low birth weight (1000–1500 g) admitted during the first time period era than in the second (Tables 1 and 2). In such settings as Fiji, these babies constitute a high-risk group but may benefit most from a referral level of neonatal care. Slightly more neonates were admitted to the NICU in second period (77 admissions per month compared to 61 in the first time period), and as we did not collect data on severity of illness (apart from diagnosis and weight). It is possible that more babies of lower severity of illness were admitted during the second period. We adjusted for this in the logistic regression analysis on outcome and need for mechanical ventilation, but only a randomized trial could fully compensate for other confounding.

Second, bubble-CPAP was provided in an environment where mechanical ventilation was available as a back-up method for ventilation if it failed; this occurred in 24 per cent (24/99) of babies initially treated with bubble-CPAP. Therefore the study cannot claim that bubble-CPAP can be applied with the expectation of similar outcomes in settings where there are no other types of ventilator assistance.

The mortality rate among mechanically ventilated neonates in this study was high: 53 per cent of 183 during the combined study periods (49.6 per cent and 58.6 per cent in the first and second study periods respectively, χ² for a difference in case-fatality rate between the two eras, p = 0.29). Complications of mechanical ventilation include nosocomial infection, endotracheal tube obstruction or malposition, accidental extubation, pulmonary overdistension or hypoventilation when inappropriate pressures are applied, and the complications of sedation and paralysis. The recognition by staff that such complications can occur may mean that mechanical ventilation is instituted late, when infants are in a moribund condition. The higher mortality among mechanically ventilated neonates during the second time period in this study might reflect further delays in intubation when bubble-CPAP was available. Other studies from neonatal intensive care units in developing countries have reported high mortality rates, for example 46 per cent overall mortality among 234 neonates in Zimbabwe, and an odds ratio for death of 12 if babies required mechanical ventilation compared to those who received conventional CPAP [3].

Safe mechanical ventilation requires a high level of expertise, and the constant availability of trained medical staff. This is rarely a reality in provincial or district hospitals in developing countries, but these hospitals admit a large proportion of seriously ill neonates. Therefore it is highly advantageous if a simpler and cheaper intervention can significantly reduce the need for mechanical ventilation with at least the same survival rate.

If neonatal intensive care services are developed before adequate primary and first-referral level neonatal care, or before effective transport and communication systems are in place, equitable improvements in neonatal survival will not occur. In Fiji, such basic public health, clinical and organizational services are in place, so it is appropriate to consider the provision of higher-level referral services in an effort to further reduce neonatal mortality. In countries undergoing such transition, perhaps an initial step in development of neonatal referral services should be the provision of bubble-CPAP, rather than the use of mechanical ventilators. Programs to improve the general quality of neonatal care, incorporating ward management, monitoring, standardization of drug therapies, prevention of hypoglycaemia and hypothermia, and audit are also essential components of a model of referral level neonatal care [4]. Without addressing these issues the impact of any form of respiratory support will be less than optimal.

There have been few evaluations of bubble-CPAP [1, 5, 6]. In a retrospective analysis, after introduction of a policy of early institution of bubble-CPAP in the delivery room, the number of days of mechanical ventilation decreased, and the postnatal weight gain increased [5]. However meta-analyses of randomized trials evaluating the early institution of CPAP (delivered by any method) failed to show a benefit. In a randomized cross-over trial in 10 premature infants considered immediately after extubation [6], blood gas results were no different whether CPAP after extubation was delivered using bubble-CPAP or using ventilator-derived CPAP.

Bubble-CPAP has the potential for being available at even lower cost than the current commercially available bubble systems used in this study. At its simplest, bubble-CPAP requires an air-compressor, oxygen blender, humidifier and tubing. A challenge for the biomedical industry is to manufacture an inexpensive appropriate technology model for further evaluation in developing countries.

References

Author notes

aColonial War Memorial Hospital, Suva, Fiji

bCentre for International Child Health, Melbourne University Department of Paediatrics, Royal Children's Hospital, Parkville, 3052, Victoria, Australia