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Postgrad Med J: first published as 10.1136/pgmj.48.562.507 on 1 August 1972. Downloaded from

Postgradulate Medical Journal (August 1972) 48, 507-513.

Artificial ventilation, prolonged endotracheal and tracheostomy in paediatric W. J. GLOVER M.B., B.Ch., F.F.A.R.C.S., D.Obst.R.C.O.G. Hospitalfor Sick Children, Great Ormond Street, London, W.C. 1

THE young infant has much less respiratory reserve from the patient to the reading on the spirometer than older children and adults; for example, his (Glover, 1965). The volume of the circuit, the peak resting consumption, per unit of body weight, inspiratory pressure reached in the circuit, and the is twice that of the adult, 7 ml/kg/min compared with frequency of ventilation determine the size of this 3-5 ml/kg/min. The diameters of distal airways re- compressibility factor. The discrepancy between the main constant from birth until about 5 years of age patient's minute volume and spirometer reading will and only then increase in size (Hogg et al., 1970). therefore be greatest in infants requiring high in- Consequently, infants and young children have a spiratory pressures. high peripheral airways resistance and a greater tendency to airways occlusion than older children. (2) Pressure The average newborn infant has about twice the The inspiratory pressure required to ventilate the surface for heat loss for each kilogram of infant varies considerably. It will be less than compared with the average adult (Cross, 1965). If 10 cm H20 if the are normal and it may be as the infant is placed in a cool environment his meta- high as 50 cm H20 in infants with pulmonary oedema copyright. bolism increases to attempt to maintain his body and bronchiolitis. It is therefore essential to be able temperature. This increase in metabolism in turn to apply pressures of this order when the clinical increases his oxygen consumption and minute condition requires it. volume. an infant in a cool environment places an additional demand on the respiratory (3) Accurate control of inspired oxygen system. In an infant already in respiratory distress In patients of all ages there is a danger of pul- this could result in respiratory insufficiency. The if importance of conserving heat in the care of ill monary damage oxygen concentrations above 500 infants is therefore of the utmost are administered for a number of days. importance. Young animals exposed to 100% oxygen at 1 http://pmj.bmj.com/ In infants, as in adults, the cause of respiratory atmosphere die in 72-96 hours. At autopsy the lungs insufficiency may be decreased respiratory move- are large, dark, heavy and liver-like in appearance. ments or pulmonary complications or a combina- Man appears less susceptible and human volunteers tion of both. For the reasons given above, however, showed a fall in pulmonary diffusion capacity after infants will reach a state of respiratory insufficiency 30 hr exposure to 98% oxygen at 1 atmosphere and more readily than older children. a fall in vital capacity after 60 hr exposure (Caldwell et al., 1966). Essential features of a paediatric It is well known that high percentages of oxygen on October 1, 2021 by guest. Protected (1) administered to premature infants may result in The tidal volume of an infant varies inversely with blindness due to retrolental fibroplasia. This com- the respiratory rate and ranges from about 10 to 30 plication may arise if the Pao2 is above 150 mmHg ml in patients of about 3.5 kg. The ventilator must in the retinal vessels. If the oxygen tension in the deliver volumes in this range to the patient. The arterial blood is monitored from the umbilical artery volume indicated by a spirometer placed in the con- in the immediate newborn period lower values will ventional position in the expiratory limb of a circuit be obtained than exist in the vessels perfusing the does not represent the patient's minute volume. eye and brain. This is due to shunting from right-to- The figure obtained from the spirometer must be left via the ductus arteriosus. Where a considerable corrected to allow for compression of the gas in the right-to-left shunt exists, as in respiratory distress, patient circuit. Gas compressed in the circuit on a Pao2 of 60-90 mmHg in the umbilical artery blood inspiration will re-expand during expiration when the sample may be acceptable (Baum & Tizard, 1970). pressure falls and contribute with the expired gas In the care of ill patients there should be no Postgrad Med J: first published as 10.1136/pgmj.48.562.507 on 1 August 1972. Downloaded from

508 W. J. Glover hesitation in raising the inspired oxygen concentra- tive provided an artificial airway is in place. If the tion as much as is necessary to maintain acceptable patient is through his nose then neither arterial oxygen tensions. Retrolental fibroplasia will ultrasonic nor compressed air are effec- not occur unless the arterial oxygen tension is abnor- tive because the nose filters out the droplets (Wolfs- mally high and the danger of pulmonary damage dorf, Swift & Avery, 1969). When however an endo- from the high inspired oxygen concentration is not tracheal or tracheostomy tube is in place, the output acute enough to outweigh the serious and im- from the must be carefully controlled as it mediate consequences of severe oxygen desatura- is easy to overload an infant's lungs with fluid. tion. Saline is more dangerous than water in this respect It is therefore essential to be able to control and consequently distilled water should be used accurately the percentage oxygen delivered by a ven- (Modell et al., 1968). tilator. The inspired oxygen concentration should in An important disadvantage of both compressed addition be checked regularly with an oxygen analy- air and ultrasonic nebulizers is the possible trans- ser. When oxygen-rich mixtures are administered it is mission of bacteria to the patient (Moffet & Allan, also necessary to check the arterial oxygen tension. 1967). Any device producing mists is liable to dis- seminate quantities of bacteria. The smaller particles (4) Humidification produced by ultrasonic nebulizers are particularly Since the artificial airway (endotracheal tube or dangerous as they penetrate deeply into the lungs tracheostomy) by-passes the patient's humidifying where pulmonary clearance mechanisms may not be mechanism, the nose, it is essential to humidify the efficient. inspired gas. This aspect is often overlooked in con- Few will meet all four criteria described sidering the merits of various ventilators. In infants above. The clinician in choosing a machine must it is of even greater importance because the inspissa- bear in mind the nature of the clinical problems with tion of resulting from the inspiration of which he will be confronted in order that he may dry gas readily blocks the narrow airways of the make the best choice for his particular purpose. patient and also the of the endotracheal or tracheostomy tube. We should try to achieve a rela- Management copyright. tive humidity of 700 or more in order to maintain Continuous nursing supervision is essential in this ciliary activity, as a low relative humidity has a work. The objective in is to retarding effect on ciliary motion (Dalhamn, 1956). maintain the patient's arterial Po2 and Pco, near There are three methods of increasing the water physiological levels and this is most easily achieved content in the inspired air and only brief comments by taking complete control of the patient's respira- are made on them here: tion. (a) Standard humidification. This involves the heat- The use of patient-triggered ventilators would ing of water over which gas is passed to the patient. seem attractive but in practice in infants breathing

If the water in the humidifier is kept at about 55° C rapidly it can be extremely difficult to achieve satis- http://pmj.bmj.com/ then all vegetative organisms are killed. This elimi- factory patient-triggering. Under-ventilation will nates an important source of proliferation of bac- then occur. teria. The disadvantage of this method is that the If one ventilates children satisfactorily so that the temperature of the inspired gas falls as it passes along Pao2 and Paco2 are approximately normal then the the inspiratory tubing to the patient. It is desirable patient will follow the cycling of the ventilator and to keep the temperature at the patient end of the cease making his own efforts. There are three excep- tubing at approximately 35°C in young infants and tions to this generalization: 33°C in older children. In young infants humidified (1) If the patient is in pain following surgery then on October 1, 2021 by guest. Protected gas is a potent factor in maintaining body tempera- an such as morphine is required to gain ture as the patient does not have to produce water control. vapour from his and thereby lose (2) If an infant is hungry then a feed is required heat. to establish control. (b) Compressed air nebulizer. This gives a variable (3) If there are large right-to-left shunts causing droplet size and a high proportion of the droplets arterial oxygen desaturation as in respiratory distress may be comparatively large. Droplets greater than syndrome or then mechanical ventilation 10 ,u are deposited in the upper . The output will not correct the blood gases and the patient tends from compressed air nebulizers is low even with high to 'fight the ventilator'. When this occurs respiratory gas flow rates. With low gas flow rates as used in depressants such as morphine or muscle relaxants paediatric practice the output may be extremely such as are required. small (Fenstermaker, 1970). In general however, control of call be (c) Ultrasonic niebilizer. These are extremely effec- accomplished without resorting to drugs. Postgrad Med J: first published as 10.1136/pgmj.48.562.507 on 1 August 1972. Downloaded from Treatment of respiratory insufficiency in paediatric surgery 509 The avoidance of muscle relaxant drugs in the circulation is good, a capillary sample from a heel management of these patients ensures that a patient prick is satisfactory. When the peripheral circulation who is being under-ventilated will attempt to is poor, a peripheral arterial sample should be taken breathe spontaneously. When a patient ceases to if the umbilical artery is not available. follow the ventilator one should assume that he is not being adequately ventilated until proved other- Pressure wise. There may be several reasons for under- As stated earlier, the pressure required to ventilate ventilation; secretions in the airway, collapse of a the lung will vary considerably depending on the air- lobe of a lung, , an accidental change way resistance and lung compliance. in the settings of the ventilator, or a fault in the The correct pressure in a particular patient is the ventilator. All these possibilities should be checked pressure which will produce adequate tidal volumes. before resorting to drugs. High pressures are not dangerous provided they are When putting an infant on a ventilator one must necessary because the pressure is largely dissipated in consider the rate, volume and pressures to be used. overcoming the high airway resistance. They would be dangerous if applied to the normal lung because Rate of the likelihood of producing a pneumothorax or of Infants in respiratory distress have a very high impairing pulmonary blood flow. respiratory rate because it is easier for the infant to increase his rate of respiration than his depth of Discontinuation of mechanical ventilation respiration. It is not necessary in mechanical venti- Once the respiratory insufficiency which created lation to follow this pattern as rates of ventilation the need for mechanical ventilation is no longer near the physiological range are satisfactory, i.e. present there is generally no difficulty in removing 30-40/min. It may be that this slower rate of venti- the patient from the ventilator. A useful method is to lation may result in more even distribution of gas, try the patient off the ventilator on an oxygen- especially in diseased lungs, but this is difficult to enriched mixture for progressively longer periods prove in clinical practice. until he is completely off. This may be achieved about 24 hr after commencing withdrawal. A patient who copyright. Minute volume is unable to tolerate near-normal inspired oxygen The difficulties encountered in attempting to study concentrations while on the ventilator is unlikely to the normal ventilation in the newborn have been be able to do without the ventilator. stated in detail by Cross (1965). The effect of a cold environment in causing an increase in ventilation in Complications the newborn has already been mentioned. The means of minimizing most complications There are probably wide variations from infant to have already been dealt with. If a pneumothorax infant. A useful average figure to take is 600 ml as occurs, a chest drain connected to an under-water the minute volume with a tidal volume of 15 ml at seal should be inserted and positive pressure ventila- http://pmj.bmj.com/ a respiratory rate of 40/min in an infant weighing tion continued. This should be very 3'5 kg. It must be appreciated that this is a mean uncommon if correct pressures are used. figure. The danger of cross-infection by the ventilator Having decided on a particular minute volume, the can be avoided by sterilizing the patient circuit after measurement of the minute volume produced by the use. ventilator presents problems. The errors involved in In infants with a very high airway resistance it is using a spirometer have been described earlier. necessary, as already described, to use pressures of Accurate measurements of tidal and minute volumes 40 cm H20 or more to inflate the lungs. In such on October 1, 2021 by guest. Protected can be obtained by using a pneumotachograph which patients the lungs become over-inflated because there measures flow and this can be integrated with time is insufficient motive force to expel the air through to measure volume. However, to do this an airtight the narrow airways during expiration (Barnes et al., fit is required around the endotracheal or tracheo- 1969). Discontinuing mechanical ventilation in these stomy tube and this is not advisable in clinical prac- patients often takes several weeks. This complication tice for the reasons given later. In addition, such is only seen in infants with a high airway resistance instruments require careful calibration and are fairly and has not been observed apart from this. difficult to use in everyday practice. In clinical practice it is more useful to assess the Prolonged endotracheal intubation and tracheostomy patient's colour and the adequacy of movement of Positive pressure ventilation of the lungs requires the chest wall as one would do in anaesthesia. the insertion of an artificial airway, either an endo- Blood gas analysis can then be done to confirm the or a tracheostomy tube. The precise adequacy of ventilation. Provided the peripheral role of endotracheal intubation or tracheostomy in Postgrad Med J: first published as 10.1136/pgmj.48.562.507 on 1 August 1972. Downloaded from

510 W. J. Glover the care of these patients has aroused considerable and this is a further reason for ensuring that the tube controversy over the past 9 years. is the correct length. The most commonly used polymer for endotra- (3) Erosion of ala or septum of nose. If the tube cheal or tracheostomy tubes is polyvinyl chloride presses on the edge of the nostril or septum, erosion (PVC). When formed by itself into a device it is hard, can appear within 24 hr. If the pressure isnotrelieved, brittle, inflexible and translucent. The heat used to erosion through the lateral wall of the nose or the form the device tends to cause thermal degradation. septum can occur in a few days. Considerable care This is shown by a yellowing of the material. is required in avoiding this complication. The tube In order to confer flexibility, various materials should be fixed in such a way that it protrudes down- known as plasticizers are used and to retard thermal wards from the nostril and therefore does not press degradation various materials known as stabilizers on the edge of the nostril. are used (Guess, 1970). (4) Blockage of the tube. This is a serious and Guess & Stetson (1968) identified a toxic substance common occurrence if care is not taken to ensure which leached out of some PVC materials when good humidification and regular aspiration of the these were inserted in rabbit muscle. Necrosis oc- tube. Instruction must be given to the nurse to ensure curred in the muscle around the plastic insert. This that she passes the suction all the way substance was an organotin compound which is one through the tube to the trachea. of the most widely used stabilizers. Most manufac- (5) Sub-glottic oedema and sub-glottic stenosis. turers have now ceased using organotin compounds This has been the most serious of all complications for this purpose and substituted epoxydized soya oil and in the early reports it appeared in almost all as a stabilizer. Users must however realize that there series. The incidence was low, 5% in some series, are various additives in PVC tubes and that not all and this encouraged the view that this complication manufacturers' products contain the same sub- was preventable. A widely held current view is that stances. the tubes used in a few cases in the earlier series In the case of tracheostomy or endotracheal tubes were too large. no satisfactory test has yet been published that re- The endotracheal tube, unlike tubes in the urethra veals the subtle effects of these devices upon mucous or oesophagus must pass a non-distensible area at copyright. tissues (Guess, 1970). the level of the . Prolonged pressure on the mucosa at this level leads to ischaemia, oede- Prolonged endotracheal intubation ma and ultimately, fibrosis. Treatment of a severe stenosisis extremelydifficult and along-term tracheo- Management and complications stomy is usually the unfortunate result. Nasotracheal intubation is generally preferred to In paediatric anaesthetic practice one normally oral intubation as it is easier to fix the nasal tube to uses the largest tube which will easily pass the the face. There is then less danger of the ventilator in order to have an airtight fit. While this is satisfac- tubing dislodging the endotracheal tube. tory for periods of a few hours, it is probable that in http://pmj.bmj.com/ In all patients, every complication of an artificial prolonged use (over 24 hr) some degree of oedema airway, whether it is an endotracheal or a tracheo- and ischaemia occurs. Stocks (1970) therefore recom- stomy tube, must be regarded as extremely serious. mends that the correct size of tube is 0.5 mm internal Consequently, it is of the utmost importance to ob- diameter less than the size which gives an airtight serve the following details: fit. A useful guide for the inexperienced is that when (I) Incorrect length of endotracheal tube. As the positive pressure is applied to the tube to inflate the infant's head may be flexed or extended in the day- lungs an audible leak occurs around the tube at to-day care of the patient, there will be some move- laryngeal level. It is this leak which leads to difficulty on October 1, 2021 by guest. Protected ment of the endotracheal tube up and down the in using the pneumotachograph referred to earlier. trachea. The length of the tube must therefore be determined fairly precisely to avoid, on the one hand, Tracheostomy endobronchial intubation and, on the other, dis- In the past decade, while experience has built up lodgement of the tube from the trachea. A useful with prolonged endotracheal intubation, the method is to insert the tube via the nose until the tip management of tracheostomy has improved con- of the tube is almost at the glottis; the tube is then siderably. Complications such as death during the cut to allow an appropriate length to pass the larynx operative procedure, blockage or dislodgement of and reach the mid-point of the trachea. the tracheostomy tube, pneumothorax, tracheal (2) Kinking. The most likely site at which kinking stenosis and delayed decannulation are largely pre- occurs is when a redundant length of tube protrudes ventable (Fearon, 1962: Holinger, Brown & Maurizi, from the nostril. The comparatively heavy connec- 1965: Aberdeen, 1965: Glover, 1970). Attention to tions to a ventilator will cause it to kink at this point detail is as important as in prolonged endotracheal Postgrad Med J: first published as 10.1136/pgmj.48.562.507 on 1 August 1972. Downloaded from Treatment ofrespiratory insufficiency in paediatric surgery 511 intubation because complications, which are on the stomy tube that will comfortably fit the trachea, one whole preventable, are serious. has a sufficiently leak-proof fit to be satisfactory clinically, thereby enabling quite high inflating pres- Technique sures to be used. There is ample evidence now that Anaesthesia. Tracheostomy in young children used inflatable cuffs increase the incidence of trachea to be performed as an emergency, often under local trauma (Stiles, 1965: Davidson et al., 1971). anaesthesia, and quite often in the ward rather than Management. As in prolonged endotracheal in- in the operating theatre. This resulted in a high tubation, continuous nursing supervision and good operative mortality from . Today the humidification are essential. If the patient shows normal practice is to administer a signs of respiratory embarrassment after the trache- via an endotracheal tube. This ensures a good airway ostomy tube is in place one must exclude the possi- and a well-oxygenated motionless patient so that a bility of a pneumothorax. planned operation can take place without haste. Changing the tracheostomy tube. If humidification In an emergency situation an endotracheal tube is adequate it is seldom necessary to change the can be passed in the ward and the tracheostomy can tube. It may be changed once per week to enable then take place as a planned procedure in the complete toilet to be done to the . In the first operating theatre. 3 days it should not be changed outside the operat- Surgical aspects. There are two points to observe: ing theatre as it may be extremely difficult to replace (1) The first tracheal ring should be left intact as it before a track has formed. division of it can lead to perichondritis and sub- Prevention of infection. The danger of infection is glottic stenosis (Watts, 1963). greatest in premature babies. If a tracheostomy is (2) No cartilage should be excised in the infant performed on such an infant the greatest care must trachea. If cartilage is excised it does not regenerate be taken to avoid infection, e.g. sterile gloves should and healing is by fibrous tissue with consequent be worn when inserting the sterile suction catheter narrowing (Watts, 1963). into the trachea. In infants even a few weeks old These points can be met by making a vertical in- there is much less danger from this source. Many cision in the mid-line of the trachea through the infants of this age already carry pathogens such as copyright. third and fourth (Holinger, et al., 1965) or third, P. aeruginosa or coagulase-positive staphylococci in fourth and fifth tracheal rings (Aberdeen, 1968). their nose, throat or rectum. It is almost inevitable After insertion of the tube it is important to flex that these organisms will be isolated, within a few the neck fully when tying the tapes as the distance days, from the tracheal aspirate. Such patients do from the tracheostomy to the posterior aspect of the not show signs ofclinical infection and it is not neces- neck is minimal in this position. Failure to do this sary to treat them with in such circum- will result in the tapes being comparatively loose with stances. A 'no-touch' technique should be used consequent danger of dislodgement of the tube post- when introducing the sterile catheter to aspirate the operatively. trachea of these older infants, i.e. the part of the http://pmj.bmj.com/ Tracheostomy tube. Most centres now use plastic catheter introduced into the trachea need not be tracheostomy tubes in infants. The tube designed by handled. Aberdeen (1965) has been very satisfactory (Stool, Decannulation. If tracheostomy has been per- Campbell & Johnson, 1968; Talbert & Haller, 1968). formed as described and if a plastic tracheostomy Tubes of this type adapt to the individual infant's tube has been used, then, provided the upper airway trachea and therefore do not cause excessive pressure was normal before the tracheostomy was done, one at any point. Silver cannulae with a removable inner does not anticipate difficulty in decannulation. tube are unnecessary. The purpose of the inner tube Damage to the first ring of the trachea is the com- on October 1, 2021 by guest. Protected is to enable a blocked tube to be cleared. Humi- monest cause of decannulation difficulty. It is of dification, which is essential for the reasons already course essential, before attempting decannulation, described, eliminates the need for an inner tube. to ensure that the infant is in a satisfactory condition, Furthermore, a rigid tube must always produce i.e. secretions should be minimal and cardiac failure pressure at certain points as it cannot adapt to the or other causes of respiratory difficulty should have individual trachea. This pressure may occur on a been eliminated. tracheal ring with consequent erosion of it and col- Young infants often do not breathe normally lapse of the trachea leading to decannulation diffi- after decannulation. This may be because co- culties. Pressure may also occur at the tip of the ordination between the larynx and respiration is lost. tube causing ulceration of the wall of the trachea. For example, the cords may remain in apposition on An important point about tracheostomy tubes in inspiration and as a result the infant struggles for air infants and young children is that an inflatable cuff and becomes cyanosed as the stoma closes. One is unnecessary. By putting in the largest tracheo- method of attempting to overcome this problem is to Postgrad Med J: first published as 10.1136/pgmj.48.562.507 on 1 August 1972. Downloaded from

512 W. J. Glover sedate the infant fairly heavily with morphine (0-2 ciated with mechanical ventilation have been in mg/kg) before decannulation. The sedated infant infants and children undergoing cardiac surgery. usually continues to sleep, the stoma closes gradually In this group of patients we are dealing with respira- and more and more air enters via the normal airway. tory insufficiency secondary to cardiac failure or When the has worn off respiration is ventilation/perfusion upsets of a transitory nature in usually well established by the normal route and the the lung following cardiac surgery. It is logical to stoma may be almost closed. give mechanical support in such conditions and, There is one important point to note. If in spite provided the surgery itself has been successful, then of sedation an infant shows signs of obstructed is usually necessary for a few respiration as the stoma closes then one must assume days only leading to full recovery. that there is an organic obstruction until proved In neonatal surgery of the oesophagus, repair of otherwise. The tracheostomy tube should be re- diaphragmatic hernia or surgery of the intestines, placed and, under full , an endo- mechanical ventilation when required is less reward- scopy should be performed to exclude such things as ing for various reasons. granulations or a mucosal flap at the site of the (a) In an otherwise normal infant undergoing stoma. oesophageal or intestinal surgery, mechanical venti- The choice of airway. Many infants and young lation is rarely necessary immediately postopera- children in several centres have been managed by tively. If it does become necessary a few days later, either prolonged endotracheal intubation or by it will probably be the result of serious complications tracheostomy. The supervision and the general such as severe peritonitis from a leaking intestinal techniques are similar for both methods and simple anastomosis or pneumonia secondary to an exten- mistakes can easily be fatal in these ill patients, sive leak from the oesophageal anastomosis. Early whichever method is used. and successful surgery may be necessary to avoid a An endotracheal tube seems to be more difficult fatal outcome from these complications. In these to manage from the nursing point of view and is less circumstances mechanical ventilation will be in a pleasant for the patient. The danger of erosion of the supportive role and survival will depend on the nose is a constant anxiety and becomes more diffi- success of the surgical management. copyright. cult to avoid as time goes on. The serious complica- (b) In congenital diaphragmatic hernia, artificial tion of sub-glottic stenosis although probably re- ventilation is often necessary before and after lated mainly to the use of too large a tube may also surgery. In such infants, requiring artificial ventila- have some relation to the duration of intubation. tion within a few hours of birth, results are poor. It would seem therefore that the case for intubation The contralateral lung may be hypoplastic in addi- becomes weaker the longer the tube is required. tion to severe hypoplasia of the lung on the affected A tracheostomy does, of course, involve a small side. In addition, there are probably severe ventila- operation and a scar on the neck. In a few patients tion/perfusion upsets in the lung as these infants there will be decannulation difficulties if the opera- may remain seriously desaturated even when venti- http://pmj.bmj.com/ tion has been performed at too high a level and in a lated with 100% oxygen. few patients granulations may form in the trachea (c) Some neonates requiring surgery may be at the stoma. premature and therefore may require artificial venti- If a patient requires an artificial airway for a few lation immediately postoperatively. Such patients days it seems reasonable to use an endotracheal tube. may have respiratory distress syndrome associated If at the end of this time the patient is not improving with their prematurity. Results will vary in this it is probably best to do a tracheostomy at that stage. group depending on the degree of prematurity, the Both endotracheal intubation and tracheostomy severity of the RDS and the extent of the surgery. on October 1, 2021 by guest. Protected have made considerable contributions to the care of It is the policy in some centres to ventilate a high ill patients and each method should be regarded as proportion of neonates in the immediate post- complementing the other rather than excluding it. operative period. This will give a much higher per- centage survival in the total results and must be The role of mechanical ventilation in paediatric remembered when interpreting those results. surgery In conclusion, it can be said that in the total field Although the causes of respiratory insufficiency of paediatric surgery mechanical ventilation has an are many and varied, mechanical ventilation is important supportive role to play. This supportive always in a supportive role while the basic cause is role must be stressed otherwise too much may be being treated. It follows that if the basic cause is not expected from it. successfully treated then mechanical ventilation will The nature of the underlying condition necessitat- merely delay the probable fatal outcome. ing artificial ventilation will usually determine the In the author's experience, the best results asso- outcome. Postgrad Med J: first published as 10.1136/pgmj.48.562.507 on 1 August 1972. Downloaded from

Treatment of respiratory insufficiency in paediatric surgery 513 References GUESS, W.L. (1970) Tissue testing of polymers. In: Prolonged ABERDEEN ,E. (1965) Tracheostomy and tracheostomy care (Ed. by J. B. Stetson). International in infants. Proceedings of the Royal Society of , Anaesthesiology Clinics, 8, 787. 58, 900. GuEss, W.L. & STETSON, J.B. (1968) Tissue reactions to ABERDEEN, E. (1968) Tracheostomy in infants. In: Operative organotin-stabilized polyvinyl chloride (PVC) . Surgery (Ed. by C. Rob and R. Smith), 2nd edn. Butter- Journal of the Amnerican Medical Association, 204, 580. worth, London. HOGG, J.C., WILLIAMS, J., RICHARDSON, J.B., MACKLEM, BARNES, N.D., GLOVER, W.J., HULL, D. & MILNER, A.D. P.T. & THURLBECK, W.M. (1970) Age as a factor in the (1969) Effects of prolonged positive pressure ventilation in distribution of lower-airway conductance and in the infancy. Lancet, ii, 1096. pathologic of obstructive lung disease. New BAUM, J.D. & TIZARD, J.P.M. (1970) Retrolental fibroplasia: England Journal of Medicine, 282, 1283. Management of . British Medical Bulletin, HOLINGER, P.H., BROWN, W.T. & MAURIZI, D.G. (1965) 26, 171. Tracheostomy in the newborn. American Journal ofSurgery, CALDWELL, P.R.B., LEE, W.L., SCHILDKRAUT, H.S. & 109, 771. ARCHIBALD, E.R. (1966) Changes in lung volume, diffusing MODELL, J.H., MOYA, F., RUIZ, B.C., SHOWERS, A.V. & capacity and blood gases in men breathing oxygen. NEWBY, E.J. (1968) Blood gas and electrolyte determina- Journal of Applied , 21, 1477. tions during exposure to ultrasonic nebulized aerosols. CROSS, K.W. (1965) Handbook of Physiology, Section 3, British Journal of Anaesthesia, 40, 20. Respiration, Vol. II. American Physiological Society, MOFFET, H.L. & ALLAN, D. (1967) Colonization of infants Washington, D.C. exposed to bacterially contaminated mists. American DALHAMN, T. (1956) Mucous flow and ciliary activity in the Journal of Diseases of Children, 114, 21. trachea of healthy rats and exposed to respiratory irritant STILES, P.J. (1965) Tracheal lesions after tracheostomy. gases. Acta physiologica Scandinavica, 36, Suppl. 123. Thorax, 20, 517. DAVIDSON, I.A., CRUICKSHANK, A.N., DUTHIE, W.H., BARGH, STOCKS, J. (1970) Prolonged nasal intubation in paediatric W. & DUNCAN, J.G. (1971) Tracheal lesions following intensive care. In: Progress in Anaesthesiology, Interna- tracheostomy. Proceedings of the Royal Society of Medi- tional Congress Series No. 200, p. 447. Excerpta Medica cine, 64, 886. Foundation, Amsterdam. FEARON, B. (1962) Acute laryngotracheobronchitis in infancy STOOL, S.E., CAMPBELL, J.R. & JOHNSON, D.G. (1968) and childhood. Pediatric Clinics of North America, 9, 1095. Tracheostomy in children: The use of plastic tubes. FENSTERMAKER, D.E. (1970) A review of ultrasonic nebuliza- Journal of Pediatric Surgery, 3, 402. tion. In: Prolonged tracheal intubation (Ed. by J. B. TALBERT, J.L. & HALLER, J.A. (1968) Improved silastic Stetson). International Clinics, 8, 949. tracheostomy tubes for infants and young children. Journal GLOVER, W.J. (1965) Mechanical ventilation in respiratory of Pediatric Surgery, 3, 408. copyright. insufficiency in infants. Proceedings of the Royal Society WATTS, J. McK. (1963) Tracheostomy in modern practice. of Medicine, 58, 902. British Journal of Surgerry, 50, 954. GLOVER, W.J. (1970) Tracheostomy in the intensive care of WOLFSDORF, J., SWIFT, D.L. & AVERY, M.E. (1969) Mist infants. In: Progress in Anaesthesiology, International therapy reconsidered; An evaluation of the respiratory Congress Series No. 200, p. 451. Excerpta Medica Foun- deposition of labelled water aerosols produced by jet and dation, Amsterdam. ultrasonic nebulizers. , 43, 799. http://pmj.bmj.com/ on October 1, 2021 by guest. Protected