374
that treatment of the presenting life threatening event takes precedence over such disadvantages. Albumin is also used before exchange transfusion to enhance bilirubin removal but the evidence for this is debated.6 This means of treatment was employed extensively in the era of Rh haemolytic disease but is now much less often used. RESPIRATORY DISTRESS SYNDROME
The facts that infants with respiratory distress syndrome are oedematous and have low serum albumin concentrations led to the idea that replacement may confer benefits. Greenough et al most recently expressed this possibility and showed that infusions caused a diuresis and weight loss in sick infants.7 However, such- studies really only support the contention that infants with respiratory distress syndrome are hypovolaemic and therefore suffer from underperfusion. What is unclear is whether this matters or not. Perhaps a more interesting line of study would be to look at the effects of plasma expansion early in postnatal life-there were studies in the late 1960s suggesting that umbilical cord oedema and serum albumin concentrations could be used as markers for the development of respiratory distress syndrome. What would happen now if we were to expand the circulating volume in the first few minutes of extrauterine life and then follow up with modem intensive care methods? It is
McClure
unlikely that albumin will be curative but it might shorten or reduce the requirement for intensive care.
Conclusion The use of these substances in neonatal care is widespread but poorly studied. This is unfortunate as any means of treatment must be formally assessed to ensure that it is properly used and maximum benefit obtained. Formal studies should be undertaken in order to achieve this goal. The Nuffweld Department of Child Health, The Queen's University of Belfast, Institute of Clinical Science, Grosvenor Road, Belfast BT12 6BJ, Northern Ireland
G McCLURE
1 Beverley DW, Pitts-Tucker TJ, Congdon PJ, Arthur RJ, Tate G. Prevention of intraventricular haemorrhage by fresh frozen plasma. Arch Dis Child
1985;60:710-3.
2 Turner T, Prowse CV, Prescott RJ, Cash JD. A clinical trial on the early detection and correction of haematocrit defects in selected high-risk neonates. Br J7 Haematol 1981;47:65-75. 3 Stone HO, Thompson HK Jr, Schmidt-Lielson K. Influence of erythrocyte on blood viscosity. Am 7 Physiol 1968;214:913. 4 Halliday HL, McClure G, Reid MMcC. Handbook of neonatal intensive care. 3rd Ed. London: Bailliere Tindall, 1989. 5 Bove JR. Transfusion-transmitted diseases: current problems and challenges. Prog Hematol 1986;XIV:123-47. 6 Chan G, Schiff D. Variance in albumin loading in exchange transfusions. J Pediatr 1976;88:609. 7 Greenough A, Greenall F, Gamsu HR. Immediate effects of albumin infusion in ill premature neonates. Arch Dis Child 1988;63:307-9.
Is routine endotracheal suction justified? New developments provide the opportunity to answer this and other questions quickly and inexpensively. The precise role of routine endotracheal suction in intubated babies is controversial. Tracheobronchial suction can reduce respiratory system resistance' and should be performed whenever secretions accumulate, to prevent airway obstruction. However there are many potential hazards, including atelectasis,2 bradycardia,3 4 decreased lung compliance,4 hypoxia,4 5 transient increases in arterial and intracranial pressure and cerebral blood flow velocity,4 6 bacteraemia,7 and pneumothorax."'0 Although they are less noticeable, fluctuations in physiological variables due to suction still occur after paralysis'" or when disconnection from the ventilator is avoided by using a side port adaptor.'2 13 Some of these hazards, for example pneumothorax, may be particularly dangerous in very preterm infants within the first three days of life,'4 a period when secretions are usually scanty. Because of the risks, some workers question whether routine endotracheal suction is justified.4 6 Nevertheless, in many neonatal units endotracheal suction at intervals of one to six hours is still a routine procedure for all intubated babies, regardless of age or gestation. We remain collectively uncertain not only whether routine endotracheal suction is justified, but how it should be done. Sometimes the baby is 'preoxygenated', sometimes not. Usually suction is preceded by instillation of 0-25-0-5 ml normal saline but occasionally as much as 2-0 ml is used. iO Sometimes the baby gets chest physiotherapy, which can increase the weight of secretions obtainediS but may exacerbate hypoxia. Endotracheal suction may be needed more often when inspired gas is poorly humidified, because this inhibits mucociliary clearance and thickens tracheobronchial secretions. In a non-randomised study, Lomholt et al reported a tenfold increase in the risk of plugging of the endotracheal tube with viscid secretions when inspired gas was less than
700/o saturated at 37°C, which is equivalent to an absolute humidity of 31 mg H20/1.6 It might thus be sensible to arrange for the hospital medical physics department to check periodically that intubated babies do not breathe gas of lower humidity than this, because inspired gas humidity varies widely during routine clinical practice (MFD O'Hagan et al, unpublished observations). For the jobbing neonatologist, these issues raise important practical questions. Is it better to have a policy of suction only when impending airway obstruction is suspected than a policy of routine suction? If so-for which babies? Should endotracheal suction be preceded by chest physiotherapy? These questions are most likely to be answered successfully in a large randomised controlled trial in which infants within each centre are randomly assigned to different policies. This would ensure that variations in case mix or clinical practice, which are inevitable, were balanced evenly between centres. To allow more than one question to be answered simultaneously a factorial design could be used so that infants were randomly assigned to either (a) routine endotracheal suction or (b) suction only when impending airway obstruction was suspected and, after the first 72 hours of life, to either (c) routine physiotherapy or (d) physiotherapy only when specifically indicated. Essential measures of outcome might include pneumothorax, duration of treatment with supplementary oxygen and with artificial ventilation, length of hospital stay, and abnormal ultrasound appearances at 6 weeks of age. It would be realistic to expect only a moderate reduction in the rate of any single adverse outcome, for example from 20% to 15%. A study would have a good chance (80% power) of showing such a reduction at a conventional level of significance (2p=0 05) if it recruited a total of 2000 infants. Now that paediatricians, nurses, epidemiologists, and parents are collaborating on an unprecedented scale to investigate the role of surfactant in the OSIRIS and CURO-
375
Is routine endotracheal suctionjustfied?
SURF 4 trials*, studies of this size have become feasible. In both these surfactant trials, a common 'core database' of descriptive variables and essential outcome measures (including those just described) is routinely collected. If this large collaborative network continued, other important questions could be answered quickly and inexpensively. Perhaps the first step is to agree an agenda of questions to be addressed.17 This might cover several other issues in respiratory management, such as the role of nasal or facemask continuous positive airway pressure before intubation in moderate respiratory disease,'8 19 or the optimum range of carbon dioxide or oxygen tension for mechanically ventilated preterm infants.20 The advent of large scale cooperation among those who care for the newborn is a major development, and we should seize the opportunity to make it permanent. WILLIAM TARNOW-MORDI
Department of Child Health, University of Dundee, Ninewells Hospital and Medical School, Dundee DDI 9SY
1 Prendiville A, Thomson A, Silverman M. Effect of tracheobronchial suction on respiratory resistance in intubated preterm babies. Arch Dis Child 1986; 61:1178-83.
*Information about the OSIRIS trial can be obtained from Dr Adrian Grant, Director, Perinatal Trials Service, National Perinatal Epidemiology Unit, Radcliffe Infirmary, Oxford OX2 6HE and about the CUROSURF 4 trial from Dr Henry Halliday, Neonatal Unit, Royal Maternity Hospital, Grosvenor Road, Belfast BT12 6BB.
2 Brandstater B, Muallem M. Atelectasis following tracheal suction in infants. Anethesiology 1969;31:468-73. 3 Cordero L, Hon EH. Neonatal bradycardia following nasopharyngeal stimulation. J Pediatr 1971;78:441-7. 4 Simbruner G, Coradello H, Fodor M, et al. Effect of tracheal suction on oxygenation, circulation and lung mechanics in newborn infants. Arch Dis Child 1981;56:326-30. 5 Danford DA, Miske S, Headley J. Effects of routine care procedures on transcutaneous oxygen in neonates: a quantitative approach. Arch Dis Child 1983;58:20-3. 6 Perlman JM, Volpe JJ. Suctioning in the preterm infant: effects on cerebral blood flow velocity, intracranial pressure and arterial blood pressure. Pediatrics 1983;72:329-34. 7 Storm W. Transient bacteremia following endotracheal suctioning in ventilated newborns. Pediatrics 1980;65:487-90. 8 Alpan G, Glick B, Peleg 0, et al. Pneumothorax due to endotracheal tube suction. Am J Perinatol 1984;1:345-8. 9 Anderson KD, Chandra R. Pneumothorax secondary to perforation of sequential bronchi by suction catheters. J Pediatr Surg 1976;11:687-93. 10 Vaughan RS, Menka JA, Giacola GP. Pneumothorax: a complication of endotracheal suction. J Pediatr 1978;92:633-4. 11 Fanconi S, Duc G. Intratracheal suctioning in sick preterm infants: prevention of intracranial hypertension and cerebral hypoperfusion by muscle paralysis. Pediatrics 1987;79:538-43. 12 Gunderson LP, McPhee AJ, Donovan EP. Partially ventilated endotracheal suction. Am J Dis Child 1986;140:462-5. 13 Durand M, Sangha B, Cabal LA, et al. Cardiopulmonary and intracranial pressure changes related to endotracheal suctioning in preterm infants. Crit Care Med 1989;17:506-10. 14 Thorburn RJ, Lipscomb AP, Stewart AL, Reynolds EOR, Hope PL. Timing and antecedents of periventricular haemorrhage and cerebral atrophy in very preterm infants. Early Hum Dev 1982;7:221-38. 15 Etches PC, Scott B. Chest physiotherapy in the newborn: effect on secretions removed. Pediatrics 1978;62:713-5. 16 Lomholt N, Cooke R, Lunding M. A method of humidification in ventilator treatment of neonates. Br J Anaesth 1968;40:335-9. 17 Anonymous. Therapeutic trials and society. Drug Ther Buld 1986;24:37-8. 18 Allen LP, Reynolds EOR, Rivers RPA, et al. Controlled trial of continuous positive airway pressure given by face mask for hyaline membrane disease. Arch Dis Child 1977;52:373-8. 19 Avery ME. Tooley WH, Keller JB, et al. Is chronic lung disease preventable? A survey of eight centers. Pediatrics 1987;79:26-30. 20 Kraybill EN, Runyan DK, Bose CL, Khan JH. Risk factors for chronic lung disease in infants with birth weights of 751 to 1000 grams. J Pediatr 1989; 115:115-20.
that treatment of the presenting life threatening event takes precedence over such disadvantages. Albumin is also used before exchange transfusion to enhance bilirubin removal but the evidence for this is debated.6 This means of treatment was employed extensively in the era of Rh haemolytic disease but is now much less often used. RESPIRATORY DISTRESS SYNDROME
The facts that infants with respiratory distress syndrome are oedematous and have low serum albumin concentrations led to the idea that replacement may confer benefits. Greenough et al most recently expressed this possibility and showed that infusions caused a diuresis and weight loss in sick infants.7 However, such- studies really only support the contention that infants with respiratory distress syndrome are hypovolaemic and therefore suffer from underperfusion. What is unclear is whether this matters or not. Perhaps a more interesting line of study would be to look at the effects of plasma expansion early in postnatal life-there were studies in the late 1960s suggesting that umbilical cord oedema and serum albumin concentrations could be used as markers for the development of respiratory distress syndrome. What would happen now if we were to expand the circulating volume in the first few minutes of extrauterine life and then follow up with modem intensive care methods? It is
McClure
unlikely that albumin will be curative but it might shorten or reduce the requirement for intensive care.
Conclusion The use of these substances in neonatal care is widespread but poorly studied. This is unfortunate as any means of treatment must be formally assessed to ensure that it is properly used and maximum benefit obtained. Formal studies should be undertaken in order to achieve this goal. The Nuffweld Department of Child Health, The Queen's University of Belfast, Institute of Clinical Science, Grosvenor Road, Belfast BT12 6BJ, Northern Ireland
G McCLURE
1 Beverley DW, Pitts-Tucker TJ, Congdon PJ, Arthur RJ, Tate G. Prevention of intraventricular haemorrhage by fresh frozen plasma. Arch Dis Child
1985;60:710-3.
2 Turner T, Prowse CV, Prescott RJ, Cash JD. A clinical trial on the early detection and correction of haematocrit defects in selected high-risk neonates. Br J7 Haematol 1981;47:65-75. 3 Stone HO, Thompson HK Jr, Schmidt-Lielson K. Influence of erythrocyte on blood viscosity. Am 7 Physiol 1968;214:913. 4 Halliday HL, McClure G, Reid MMcC. Handbook of neonatal intensive care. 3rd Ed. London: Bailliere Tindall, 1989. 5 Bove JR. Transfusion-transmitted diseases: current problems and challenges. Prog Hematol 1986;XIV:123-47. 6 Chan G, Schiff D. Variance in albumin loading in exchange transfusions. J Pediatr 1976;88:609. 7 Greenough A, Greenall F, Gamsu HR. Immediate effects of albumin infusion in ill premature neonates. Arch Dis Child 1988;63:307-9.
Is routine endotracheal suction justified? New developments provide the opportunity to answer this and other questions quickly and inexpensively. The precise role of routine endotracheal suction in intubated babies is controversial. Tracheobronchial suction can reduce respiratory system resistance' and should be performed whenever secretions accumulate, to prevent airway obstruction. However there are many potential hazards, including atelectasis,2 bradycardia,3 4 decreased lung compliance,4 hypoxia,4 5 transient increases in arterial and intracranial pressure and cerebral blood flow velocity,4 6 bacteraemia,7 and pneumothorax."'0 Although they are less noticeable, fluctuations in physiological variables due to suction still occur after paralysis'" or when disconnection from the ventilator is avoided by using a side port adaptor.'2 13 Some of these hazards, for example pneumothorax, may be particularly dangerous in very preterm infants within the first three days of life,'4 a period when secretions are usually scanty. Because of the risks, some workers question whether routine endotracheal suction is justified.4 6 Nevertheless, in many neonatal units endotracheal suction at intervals of one to six hours is still a routine procedure for all intubated babies, regardless of age or gestation. We remain collectively uncertain not only whether routine endotracheal suction is justified, but how it should be done. Sometimes the baby is 'preoxygenated', sometimes not. Usually suction is preceded by instillation of 0-25-0-5 ml normal saline but occasionally as much as 2-0 ml is used. iO Sometimes the baby gets chest physiotherapy, which can increase the weight of secretions obtainediS but may exacerbate hypoxia. Endotracheal suction may be needed more often when inspired gas is poorly humidified, because this inhibits mucociliary clearance and thickens tracheobronchial secretions. In a non-randomised study, Lomholt et al reported a tenfold increase in the risk of plugging of the endotracheal tube with viscid secretions when inspired gas was less than
700/o saturated at 37°C, which is equivalent to an absolute humidity of 31 mg H20/1.6 It might thus be sensible to arrange for the hospital medical physics department to check periodically that intubated babies do not breathe gas of lower humidity than this, because inspired gas humidity varies widely during routine clinical practice (MFD O'Hagan et al, unpublished observations). For the jobbing neonatologist, these issues raise important practical questions. Is it better to have a policy of suction only when impending airway obstruction is suspected than a policy of routine suction? If so-for which babies? Should endotracheal suction be preceded by chest physiotherapy? These questions are most likely to be answered successfully in a large randomised controlled trial in which infants within each centre are randomly assigned to different policies. This would ensure that variations in case mix or clinical practice, which are inevitable, were balanced evenly between centres. To allow more than one question to be answered simultaneously a factorial design could be used so that infants were randomly assigned to either (a) routine endotracheal suction or (b) suction only when impending airway obstruction was suspected and, after the first 72 hours of life, to either (c) routine physiotherapy or (d) physiotherapy only when specifically indicated. Essential measures of outcome might include pneumothorax, duration of treatment with supplementary oxygen and with artificial ventilation, length of hospital stay, and abnormal ultrasound appearances at 6 weeks of age. It would be realistic to expect only a moderate reduction in the rate of any single adverse outcome, for example from 20% to 15%. A study would have a good chance (80% power) of showing such a reduction at a conventional level of significance (2p=0 05) if it recruited a total of 2000 infants. Now that paediatricians, nurses, epidemiologists, and parents are collaborating on an unprecedented scale to investigate the role of surfactant in the OSIRIS and CURO-
375
Is routine endotracheal suctionjustfied?
SURF 4 trials*, studies of this size have become feasible. In both these surfactant trials, a common 'core database' of descriptive variables and essential outcome measures (including those just described) is routinely collected. If this large collaborative network continued, other important questions could be answered quickly and inexpensively. Perhaps the first step is to agree an agenda of questions to be addressed.17 This might cover several other issues in respiratory management, such as the role of nasal or facemask continuous positive airway pressure before intubation in moderate respiratory disease,'8 19 or the optimum range of carbon dioxide or oxygen tension for mechanically ventilated preterm infants.20 The advent of large scale cooperation among those who care for the newborn is a major development, and we should seize the opportunity to make it permanent. WILLIAM TARNOW-MORDI
Department of Child Health, University of Dundee, Ninewells Hospital and Medical School, Dundee DDI 9SY
1 Prendiville A, Thomson A, Silverman M. Effect of tracheobronchial suction on respiratory resistance in intubated preterm babies. Arch Dis Child 1986; 61:1178-83.
*Information about the OSIRIS trial can be obtained from Dr Adrian Grant, Director, Perinatal Trials Service, National Perinatal Epidemiology Unit, Radcliffe Infirmary, Oxford OX2 6HE and about the CUROSURF 4 trial from Dr Henry Halliday, Neonatal Unit, Royal Maternity Hospital, Grosvenor Road, Belfast BT12 6BB.
2 Brandstater B, Muallem M. Atelectasis following tracheal suction in infants. Anethesiology 1969;31:468-73. 3 Cordero L, Hon EH. Neonatal bradycardia following nasopharyngeal stimulation. J Pediatr 1971;78:441-7. 4 Simbruner G, Coradello H, Fodor M, et al. Effect of tracheal suction on oxygenation, circulation and lung mechanics in newborn infants. Arch Dis Child 1981;56:326-30. 5 Danford DA, Miske S, Headley J. Effects of routine care procedures on transcutaneous oxygen in neonates: a quantitative approach. Arch Dis Child 1983;58:20-3. 6 Perlman JM, Volpe JJ. Suctioning in the preterm infant: effects on cerebral blood flow velocity, intracranial pressure and arterial blood pressure. Pediatrics 1983;72:329-34. 7 Storm W. Transient bacteremia following endotracheal suctioning in ventilated newborns. Pediatrics 1980;65:487-90. 8 Alpan G, Glick B, Peleg 0, et al. Pneumothorax due to endotracheal tube suction. Am J Perinatol 1984;1:345-8. 9 Anderson KD, Chandra R. Pneumothorax secondary to perforation of sequential bronchi by suction catheters. J Pediatr Surg 1976;11:687-93. 10 Vaughan RS, Menka JA, Giacola GP. Pneumothorax: a complication of endotracheal suction. J Pediatr 1978;92:633-4. 11 Fanconi S, Duc G. Intratracheal suctioning in sick preterm infants: prevention of intracranial hypertension and cerebral hypoperfusion by muscle paralysis. Pediatrics 1987;79:538-43. 12 Gunderson LP, McPhee AJ, Donovan EP. Partially ventilated endotracheal suction. Am J Dis Child 1986;140:462-5. 13 Durand M, Sangha B, Cabal LA, et al. Cardiopulmonary and intracranial pressure changes related to endotracheal suctioning in preterm infants. Crit Care Med 1989;17:506-10. 14 Thorburn RJ, Lipscomb AP, Stewart AL, Reynolds EOR, Hope PL. Timing and antecedents of periventricular haemorrhage and cerebral atrophy in very preterm infants. Early Hum Dev 1982;7:221-38. 15 Etches PC, Scott B. Chest physiotherapy in the newborn: effect on secretions removed. Pediatrics 1978;62:713-5. 16 Lomholt N, Cooke R, Lunding M. A method of humidification in ventilator treatment of neonates. Br J Anaesth 1968;40:335-9. 17 Anonymous. Therapeutic trials and society. Drug Ther Buld 1986;24:37-8. 18 Allen LP, Reynolds EOR, Rivers RPA, et al. Controlled trial of continuous positive airway pressure given by face mask for hyaline membrane disease. Arch Dis Child 1977;52:373-8. 19 Avery ME. Tooley WH, Keller JB, et al. Is chronic lung disease preventable? A survey of eight centers. Pediatrics 1987;79:26-30. 20 Kraybill EN, Runyan DK, Bose CL, Khan JH. Risk factors for chronic lung disease in infants with birth weights of 751 to 1000 grams. J Pediatr 1989; 115:115-20.
