Surfactant replacement therapy for severe neonatal respiratory distress syndrome: implications for nursing care

', UK Ltd 1991 © Longman Group

Midwifery

Surfactant replacement therapy for severe neonatal respiratory distress syndrome: implications for nursing care Norma Sittlington, Richard Tubman and Henry L Halliday

This study, which was part o f a E u r o p e a n multicentre randomised controlled trial o f surfactant administration for severe respiratory distress syndrome, monitored the progess and nursing care o f the g r o u p o f babies enrolled in Belfast. In total 33 p r e t e r m babies with birth weights between 7 0 0 - 2 0 0 0 g were studied. Nineteen babies were treated with surfactant and fourteen acted as controls, receiving conventional t h e r a p y with mechanical ventilation alone. All the babies had severe respiratory distress s y n d r o m e requiring mechanical ventilation in oxygen concentrations greater than 60% by the age o f fifteen hours. T h e aim of the study was to d e t e r m i n e the effect on nursing workload of giving surfactant to babies with severe respiratory distress syndrome. T h e duration o f care, such as the length o f time the babies required intensive care and subsequent hospitalisation was calculated for each baby. T h e characteristics of the treated and control babies were similar b u t survival in the treated g r o u p was significantly greater (79% vs 36%, p < 0.05). T h e r e were no significant differences b e t w e e n the groups for individual nursing requirements. H o w e v e r d u e to the increase in n u m b e r s o f surviving surfactant treated babies there was a threefold increase in cumulative nursing workload. Surfactant replacement t h e r a p y effectively modifies the course o f respiratory distress s y n d r o m e b u t also increases the nursing workload and the need for intensive care. This has implications for staffing and financial s u p p o r t of Neonatal Intensive Care Units once surfactant replacement becomes a routine treatment.

Norma Sittlington RGN RSCN RM DM, Midwifery Sister, Neonatal Unit, Royal Maternity Hospital, Grosvenor Road, Belfast. Richard Tubman BSc MB BCh MRCP, Perinatal Research Fellow, Royal Maternity Hospital, Grosvenor Road, Belfast. Henry L Halliday MD FRCP FRCP (E), Consultant Paediatrician with special interest in Neonatology, Royal Maternity Hospital, Belfast City Hospital & Mater Infirmorum Hospital, Belfast and Honorary Lecturer, Department of Child Health, The Queen's University of Belfast. Manuscript accepted 9 August 1990 Correspondence and requests for offprints to NS

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INTRODUCTION In 1970 the UK National Survey of Perinatal Mortality (Chamberlain et al, 1975) showed that respiratory distress syndrome (RDS) was the commonest cause of death in the first week of life accounting for 3.2 deaths per thousand live births and contributing to 32% of all deaths in the first week of life. Despite advances in antenatal care, e.g. assessment of fetal lung maturity and maternal glucocorticoid administration,

MIDWIFERY

babies continue to be born prematurely and develop RDS. These babies often require mechanical ventilation and prolonged periods of intensive nursing care. Respiratory distress syndrome is due to a deficiency of pulmonary surfactant. T h e condition mainly affects the preterm baby particularly those u n d e r 34 weeks' gestation (Usher et al, 1971). Surfactant, a potent surface tension lowering agent, is essential for adequate lung expansion and deficiency leads to alveolar collapse with intrapulmonary shunting of blood, hypoxaemia, hypercarbia and acidosis. Conventional treatment includes supplemental oxygen therapy and assisted ventilation, continuous positive airway pressure (CPAP) or mechanical ventilation if respiratory failure or apnoea occur. Over the past 20 years attempts have been made to treat RDS by surfactant replacement. 'The surfactant used has been of two types, artificial produced by mixing chemicals in the laboratory or natural produced from extracts of animal lungs. T h e results o f early attempts at treatment with artificial surfactant were disappointing due to both the content and method of administration of the surfactant (Robillard et al, 1964; Chu et al, 1967). However, more recently use of, artificial lung expanding compound (ALEC) at birth by Morley et al (1981) has led to a reduction in mortality of preterm babies. In the 1980s a number of randomised clinical trials have shown that natural surfactant is effective in the treatment of RDS. These surfactants include: human surfactant, derived from amnior tic fluid (Hallman et al, 1985); calf lung surfactant extract (Enhorning et al, 1985) and Surfactant - T A (Fujiwara et al, 1980), both derived from bovine lungs; and Curosurf (Collaborative European Multicentre Study Group [CEMSG], 1988), derived from porcine lungs. These trials demonstrate that natural surfactant replacement increases survival and reduces the frequency of serious complications, in particular pulmonary interstitial emphysema and pneumothorax (Hallman et al, 1985; Enhorning et al, 1985; CEMSG, 1988). T h e r e is also an increase in the n u m b e r of babies surviving without bronchopulmonary dysplasia, a form of neonatal M I DW.- B

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chronic lung disease (CEMSG, 1988). Our unit took part in the European multicentre trial of porcine surfactant replacement (Curosurf) from 1985 to 1987. In this report we have tried to assess the impact of this new form of treatment on the nursing care of the preterm baby with severe RDS. Nursing care of the preterm baby Neonatal intensive care can be defined as 'provision of continuous skilled supervision by nursing and medical staff to babies who may be receiving assisted ventilation, total parenteral nutrition and continuous cardiorespiratory monitoring (British Paediatric Association, 1985). Preterm babies with signs of respiratory distress are initially given supplemental oxygen, usually by a perspex headbox. An umbilical or peripheral arterial catheter is inserted to facilitate regular blood gas analysis. Heart rate, respiratory pattern and blood pressure are monitored continuously. Investigations on admission include haematocrit, blood glucose, cultures of blood, surface swabs and gastric aspirate, and chest radiography to confirm the diagnosis and exclude other conditions such as group B, beta haemolytic streptococcal sepsis or pneumothorax. Mechanical Ventilation Mechanical ventilation is indicated should respiratory failure supervene, i.e., when one or more of the following is present: PaO2 < 6kPa (45 mmHg) in 100% oxygen on CPAP of 6-8 cm H20; PaCO2 > 8-10kPa (60-75mmHg); pH < 7.20, or intractable apnoea (Halliday et al, 1989b). A pressure limited, time cycled ventilator e.g. Sechrist (Anaheim, California) is commonly used. Mechanical ventilation is not without its risks; the ventilated baby requires skilled and diligent nursing care with close observation for any deterioration in his condition. This may be caused by kinking, blockage or displacement of the endotracheal tube, or the development o f pneumothorax. Ventilator settings and concentration of inspired oxygen must be checked frequently. If tracheal secretions are copious there is a risk of endotracheal tube blockage and

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MIDWIFERY

regular suction of the airway should be performed u n d e r these circumstances.

Monitoring Heart rate, respiratory rate, oxygen saturation and blood pressure are monitored continuously. Deterioration in the baby's condition is often indicated by' bradycardia, apnoea or falling oxygen saturation. Skilled observation is therefore required and the midwife or nurse must be able to detect and interpret these changes and intervene promptly when indicated. Nutrition Total parenteral nutrition (TPN) is used when the baby is unable to tolerate enteral feeds. T P N solutions contain amino-acids, carbohydrate and fat, with added vitamins and minerals which may be given by peripheral or central venous catheter. T h e individual daily requirements are calculated taking into account the baby's weight, age and blood urea and electrolyte values. Maintenance o f a strict aseptic technique is essential When dispensing and changing parenteral fluids to prevent bacterial contamination. Meticulous care of the infusion site is necessary to prevent extravasation into the tissues which can lead to skin necrosis. Milk feeding is introduced when the baby's clinical condition has improved. This is often given via a silastic oral feeding tube, which is passed through the pylorus into the j e j u n u m (transpyloric or orojejunal feeding). T h e volume of milk given is gradually increased as tolerated with careful monitoring of vomiting, abdominal distension or blood stained stools, which may be features o f necrotising enterocolitis.

Parental Involvement Parental contact with the baby begins at birth. Following delivery the m o t h e r is encouraged to see, touch and hold her baby if at all possible. She is also provided with a photograph. Frequent visiting by parents is welcomed. A mother who wishes to breast feed is encouraged and helped to express breast milk, as often this may be the only thing that she is initially able to do for her ill baby.

When the baby no longer requires assisted ventilation and can tolerate enteral feeds he is usually transferred to the high dependency and later to the special care area of the nursery to undergo a period o f convalescence in preparation for discharge. At this stage m o r e active parental involvement in the actual day to day care of the baby is encouraged. Continual support of the parents is o f the utmost importance for the future d e v e l o p m e n t of the baby. A r a p p o r t between parents, nursery staff and paediatricians must be built u p as many fears and anxieties can be dispelled by discussion. Good communication is essential in dealing with parents of the p r e t e r m baby. T h e midwife or nurse has a major role to play in giving advice, education and e n c o u r a g e m e n t in preparation for discharge.

METHODS We monitored the progress and nursing workload involved in the care of a g r o u p of babies enrolled in the Belfast arm o f the European Multicentre Trial of natural porcine surfactant replacement C u r o s u r f (CEMSG, 1988; McCord, 1988). Thirty three preterm babies were studied, 19 babies were randomised to receive surfactant and 14 acted as controls. Criteria for inclusion in the study were: birth weight 700-2000 g, age 2-15 h and clinical and radiological evidence o f severe RDS (CEMSG, 1988). All babies received mechanical ventilation with a fraction o f inspired oxygen I>0.60. T r e a t e d babies received 2.5 ml/kg C u r o s u r f via the endotracheal tube, followed by 2min of manual ventilation whereas control babies did not receive a placebo but were manually ventilated for 2 min. T h e nursing and medical care of both groups o f babies after randomisation was the same. T h e treated babies usually responded to surfactant therapy with an immediate decrease in need for oxygen as assessed by pulse oximetry (CEMSG, 1988; Halliday et al, 1989a). During this acute phase the babies needed very close observation of vital signs including blood pressure, and ventilator

MIDWIFERY 23 Table 1 Clinical characteristics of babies entered into the study

Gestational age (wk)* Birth weight (g)* Male(n,%) Survival (N, %)

Treated (19)

Control (14)

27.8 1250 11 15

28.9 1333 8 5

(1.8) (330) (58%) (79%)

(212) (360) (57%) (36%)**

*Mean (sd) * * p = 0.03, Fisher's Exact Test

Table 2 Characteristics of surviving babies

Survival <1200g (n, %) Gestational age (wk)* Birth weight (g)*

Treated (15)

Control (5)

7 (47%) 28.1 (1.7) 1287 (337)

0 (0%) 30.0 (2.5)~ 1625 (261)$

*Mean (SD) l"t = 2.34, df = 18, p = 0.03 Ct = 2.20, df = 18, p = 0.04

settings were often altered according to frequent blood gas analyses. Falling blood pressure indicated the need for volume expansion with blood, plasma or albumin. Treated babies in the European Muhicentre Study had lower mortality and pneumothorax rates than controls (CEMSG, 1988). We documented duration of stay in hospital and length of time each baby required assisted ventilation, cardiorespiratory monitoring, parenteral nutrition, and incubator care. Results were expressed as both a median (range) and as a cumulative total for each form of care. Statistical comparison between treated and control groups was performed using the independent t, MannWhitney U and Fisher's exact tests where relevant. P values where quoted are for two-tailed tests.

FINDINGS TEe clinical characteristics o f the babies entered into the study are shown in Table 1. T h e r e were no significant differences in birth weight, gestational age or the proportion o f male babies

between the groups. T h e survival rate of treated babies was more than twice that of controls (79% vs 36%, P < 0.05). Not only was overall survival increased in the treated group, but the surviving treated babies had a significantly lower mean birthweight and gestational age than controls (Table 2). There were no survivors weighing less than 1200g in the control group. When individual requirements for duration o f nursing care were expressed as a median (range) n u m b e r of days, there were no significant differences between treated and control babies (Table 3). However when the n u m b e r of cumulative care days was calculated, the overall workload was substantially greater in the treated group (Table 4). The increase in nursing workload for this group o f babies with severe RDS was about 3-4 fold for treated babies. T h e r e were no significant differences in workload between groups for those babies who died.

Table 3 Duration of various components of nursing and medical care*

Duration of ventilation (days) Duration of TPN (days) Duration of monitoring (days) Time in incubator (days)

Treated (19)

Controls (14)

9 (3-53) 35 (10-97)

11 (7-39) 43 (20-46)

54 (22-120)

53 (30-55)

61 (36-173)

56 (42-67)

*Median (range)

Table 4 Cumulative duration of care for the two groups of babies Treated (19) Ventilation (days) TPN (days) Monitoring (days) Incubator (days) Hospital stay (days)

Control (14)

T:C ratio*

305 564

79 194

3.9:1 2.9:1

890

240

3.7:1

833

235

3.5:1

1164

280

4.2:1

*T:C ratio = ratio of duration of care for treated: control babies

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MIDWIFrRY

DISCUSSION T h e findings o f this s t u d y suggest t h a t a l t h o u g h s u r f a c t a n t r e p l a c e m e n t t h e r a p y is effective in the t r e a t m e n t o f RDS, it is associated with a substantial increase in n u r s i n g w o r k l o a d . T h i s increase is d u e to t h e i m p r o v e d survival o f small p r e t e r m babies w h o w o u l d have o t h e r w i s e d i e d h a d t h e y n o t b e e n t r e a t e d with s u r f a c t a n t . T h e s e babies s u b s e q u e n t l y r e q u i r e d p r o l o n g e d p e r i o d s o f hospitalisation a n d b o t h intensive a n d special care n u r s i n g . T h e s e findings have a n u m b e r o f implications f o r the f u t u r e . S u r f a c t a n t is n o w a r o u t i n e f o r m o f t r e a t m e n t for babies with s e v e r e RDS in those units w h e r e its use was p i o n e e r e d . T h e babies in the E u r o p e a n M u l t i c e n t r e S t u d y w e r e very ill a n d c o n s t i t u t e d only t h e most ill 10% o f babies n e e d i n g m e c h a n i c a l ventilation for RDS in o u r unit ( a b o u t 15 babies p e r year). L a r g e scale c o m m e r c i a l p r o d u c t i o n o f a n u m b e r o f types o f artificial o r n a t u r a l s u r f a c t a n t s is now u n d e r way a n d these will soon b e c o m e m o r e widely available. I f these s u r f a c t a n t s a r e u s e d to t r e a t g r e a t e r n u m b e r s o f babies in the U K a n d E u r o p e t h e n the overall costs o f c a r e m a y i n c r e a s e significantly. As m o r e babies will be e x p e c t e d to survive, n u r s i n g w o r k l o a d within n e o n a t a l units will increase. T r e a t i n g p r e t e r m babies who have less severe RDS m a y s h o r t e n t h e d u r a t i o n o f intensive care given to t h e m , b u t t h e y m a y still require prolonged hospitalisation because of i m m a t u r i t y . T o this m u s t also b e a d d e d the cost o f e x t r a doses o f surfactant, which c u r r e n t l y is in the o r d e r o f £ 3 0 0 - 5 0 0 p e r dose. W h e n p l a n n i n g f u t u r e p e r i n a t a l services full r e g a r d m u s t t h e r e f o r e be m a d e f o r sufficient e d u c a t i o n a n d t r a i n i n g o f midwives a n d nurses involved in the c a r e o f p r e t e r m babies, a n d a d e q u a t e staffing levels m u s t b e m a i n t a i n e d to e n s u r e a d e q u a t e a n d safe n u r s e - b a b y ratios. W e believe t h a t s u r f a c t a n t r e p l a c e m e n t has a m a j o r role to play in the t r e a t m e n t o f t h e sick p r e t e r m baby. It is vital t h e r e f o r e to e n s u r e t h a t p r o v i s i o n is m a d e f o r a d e q u a t e f u n d i n g to c o p e with the n e e d f o r e x t r a staffing a n d ancillary services that will result f r o m t h e r o u t i n e use o f surfactant. T h i s is all the m o r e i m p o r t a n t in t h e p r e s e n t

e c o n o m i c climate w h e r e we a r e r e q u i r e d by G o v e r n m e n t to j u s t i f y o u r s p e n d i n g policies. L a r g e r trials o f s u r f a c t a n t r e p l a c e m e n t are c u r r e n t l y b e i n g o r g a n i s e d in the U K a n d E u r o p e a n d these s h o u l d p r o v i d e us with m o r e i n f o r m a tion r e g a r d i n g b o t h t h e n u r s i n g a n d financial implications o f s u r f a c t a n t r e p l a c e m e n t t h e r a p y .

References British Paediatric Association and British Association for Perinatal Paediatrics 1985 Categories of babies requiring neonatal care. Archives of Disease in Childhood 60:599-60 Chamberlain R, Chamberlain G, Howlett Bet al 1975 British births 1970, Vol 1, the first week of life. Heinemann, London Chu J, Clements J A, Cotton E K et al 1967 Neonatal pulmonary ischaemia: clinical and physiological studies. Pediatrics 40:709-82 Collaborative European Multicentre Study Group 1988 Surfactant Replacement Therapy for severe neonatal respiratory distress syndrome: An International Randomised Clinical Trial. Pediatrics 82:683-91 Enhorning G E, Shennan A, Possmayer F et al 1985 Prevention of neonatal respiratory distress by tracheal instillation or surfactant. A randomised clinical trial. Pediatrics 76:145-53 Fujiwara T, Maeta H, Chida Set al 1980 Artificial surfactant therapy in hyaline membrane disease. Lancet i: 55-59 Halliday H L, McCord F B, McClure B G, Reid M McC 1989a Acute effects of instillation of surfactant in severe respiratory distress syndrome. Archives of Disease in Childhood 64:13-16 Halliday H L, McClure B G, Reid M McC 1989b Handbook of Neonatal Intensive Care. Third Edition. Bailliere Tindall, London Hallman M, Merritt T A, Jarvenpaa A et al 1985 Exogenous human surfactant for treatment of severe respiratory distress syndrome: a randomised prospective clinical trial. Journal of Pediatrics 106: 963-69 McCord F B, Curstedt T, Halliday H Let al 1988 Surfactant treatment and incidence of intraventricular haemorrhage in severe respiratory distress syndrome. Archives of Disease in Childhood 63:10-16 Morley C J, Bangham A D, Millar Net al 1981 Trial of artificial lung surfactant and its effect on very premature babies. Lancet i: 64-68 Robillard E, Alarie Y, Deagenais-Perusse P, et al 1964 Microaerosol administration of synthetic dipalmitoyllecithin in the respiratory distress syndrome: a preliminary report. Canadian Medical Society Journal 1964; 90:50-57 Usher R H, Allen A C, McClean F H 1971 Risk of respiratory distress syndrome related to gestational age, route of delivery and maternal diabetes. American Journal of Obstetrics and Gynecology 111 : 826-32