OCTOBER 1962

Cuffed Tracheotomy Tube vs. Tank Respirator fo·r Prolonged Artificial Ventilation

Peter Safar, M.D. Pittsburgh Barnett Berman, M.D. Evans Diamond, M.D. Karol Hoffman, M.D. Warren Holtey, M.D. Herman Moore, M.D. and Barrett Scoville, M.D. Baltimore

• During the 1960 epidemic of polio­ tions may benefit from controlled ven­ myelitis in Maryland, 24 apneic patients tilation (i.e., passive hyperventilation), were given respiratory aid with volume-cy­ which abolishes the work of breathing cled intermittent positive pressure respira­ and thus reduces their oxygen con­ tors. A routine was established which pro­ sumption and acidosis. vided adequate ventilation and prevented In the United States of America, pro­ major pulmonary complications. The rou­ longed artificial ventilation of patients tine included the use of large bore cuffed with poliomyelitis has been performed tracheotomy tubes, humidification, artificial most commonly with the tank respira­ coughing and sighing, changing of position, sterile tracheobronchial aspiration and mon­ tor (iron lung). In contrast, in Europe itoring of ventilation. Five of the 24 patients intermittent positive pressure ventila­ died within three months. Two of the 5 tion via cuffed tracheotomy tube was deaths could possibly have been prevented. preferred. In most American centers Six of the survivors will require artificial prolonged artificial ventilation has respiration for an indefinite period. In addi­ been under the direction of internists, tion, circulatory and respiratory parameters while in most European centers it has of 4 patients were studied during positive been under the direction of anesthesi­ pressure ventilation via tracheotomy and ologists. Are these differences in prac­ with the tank respirator. Clinical results of tice merely differences in "habit," or is tank respiration during previous epidemics one method actually superior to the are compared with results of positive pres­ other? sure ventilation via tracheotomy. Physiologically, both methods are In spite of the anticipated disappear­ positive pressure technics, since in each ance of paralytic poliomyelitis, pro­ the intrapulmonary pressure during in­ longed artificial ventilation will remain flation is higher than the pressure sur­ of practical importance. New indica­ rounding the patient. Therefore, the tions for prolonged artificial ventilation effects on lungs and circulation are are receiving increasing attention. They comparable. include: (1) respiratory paralysis from During the 1952 epidemic of polio­ intoxication or from deliberate curari~ myelitis in Scandinavia, Lassen,1 Ibsen zation in status epilepticus, tetanus or and others treated more than .300 pa­ prolonged hypothermia; (2) severe dis­ tients by prolonged artificial ventila­ ease of the lungs; (3) severe trauma of tion. Of the first 31 patients, who were the chest wall; (4) restrictions of breath­ ing movements, for instance, after an From the Departments of Anesthesiology and abdominal operation for abdominal Medicine, Baltimore City Hospitals, and the De­ partment of Anesthesiology, University of Pitts­ distention or obesity, and (5) metabolic burgh School of Medicine. The study was supported by the Research and acidosis, for instance, after an open heart Development Division of the Surgeon General, U. S. operation or prolonged hypoxia or dur­ Army Contract No. DA-49-193-MD-2160, and in part by Johnson & Johnson, New Brunswick, N. J. ing severe shock. Desperately ill pa­ Read at the Thirty-Ninth Annual Session of the American Congress of Physical Medicine a.nd tients suffering from reversible condi- Rehabilitation, Cleveland, Sept. 1, 1961.

487 488 ARCHIVES of PHYSICAL MEDICINE & REHABILITATION Oct., 1962

treated with tank respirators, 27 (87 per persons taking care of the patients in cent) died in the acute phase of the dis­ the two groups seemed comparable. ease, primarily because of inadequate Most of the patients who were placed ventilation. Of the others, who were in the tank respirator without tra­ treated with intratracheal intermittent cheotomy had to be tracheotomized later positive pressure ventilation (either because of accumulation of secretions manually by compression of a breath­ in the tracheobronchial tree and be­ ing bag or mechanically with a respira­ cause of obstruction of the upper air­ tor), only approximately 40 per cent way by soft tissue obstruction. died; most deaths were late and due to All patients receiving prolonged in­ pulmonary infection. termittent positive pressure ventilation at the Baltimore City Hospital in 1960 Material and Methods were tracheotomized. The effectiveness of intermittent positive pressure ven­ At the Baltimore City Hospital, tilation is always increased by the use which receives almost all patients with of a tracheal tube or tracheotomy tube, paralytic poliomyelitis in Maryland, since the tube prevents gastric insufila­ the tank respirator was used exclusively tion and air leaks, facilitates tracheo­ prior to 1956. Since 1957, intermittent bronchial suction and provides a pa­ positive pressure ventilation has been tent airway at all times. Sometimes used exclusively in the intensive care intermittent positive pressure ventila­ unit.2 More than 100 patients were tion was started via an orotracheal treated with various types of positive tube, and tracheotomy was performed pressure respirators, primarily for prob­ later, when the need for prolonged ar­ lems other than poliomyelitis, since tificial ventilation became apparent. paralytic poliomyelitis has almost dis­ When intubation is necessary for more appeared. It was natural, therefore, that than one or two days, tracheotomy is intratracheal intermittent positive pres­ advisable, because the orotracheal tube sure ventilation was used exclusively may produce laryngeal edema and may also during the 1960 epidemic of polio­ become plugged with crusts, since it myelitis in Maryland, when 88 patients lacks an inner cannula. In addition, the with acute poliomyelitis were admitted conscious person tolerates a trache­ unexpectedly to the hospital, and 24 of ofomy tube better than an orotracheal them required prolonged artificial ven­ tube. tilation. With adults, intermittent positive Tracheotomy-Although the Scandi­ pressure ventilation was performed via navians showed that intermittent ·posi­ cuffed tracheotomy tubes, to prevent in­ tive pressure ventilation via cuffed halation of gastric contents or saliva tracheotomy tube can be carried out around the cannula and to permit con­ continuously and effectively for years, stant volume ventilation without leak­ their results with this method should age of air. Tracheal ulceration did not not be compared with their results with occur when the cuff was inflated only the tank respirator, for the following sufficiently to prevent leakage of air. reasons: 1. Their patients treated with The cuff was deflated briefly every two the tan:k resnirator were not trache­ hours. In conscious patients with intact otomized, while the other patients were. reflexes of the upper airway, a minimal 2. Their patierits treated with the tank leak between cuff and tracheal wall was respirator wer·e the first ones treated maintained to allow the patient to talk during the ·epidemic, at· a time when during inflations. 3 Inspite of this mini­ undoubtedly the staff had little experi­ mal leak, constant volume ventilation ence and was overwhelmed by the great could be maintained. number of patients. . · The indications for tracheotomy ·of In contrast, almost all patients treated patients with poliomyelitis were ap­ with the ta:rik respirator at the Balti­ proximately the same for those tre'ated more. City Hospital were tracheoto­ with ' the tank respirator and those mized, and the experience ,and skill of treated by intiatracheal intermittent ARTIFICIAL VENTILATION-SAFAR, et al 489

positive pressure ventilation: (1) de­ creased vital capacity; (2) difficulty in swallowing; (3) the presence of secre­ tions in the airways; weak cough; (5) ascending paralysis, and (6) signs of encephalitis. Tracheotomy care, however, was not comparable, since before 1956 suction was not performed by a sterile atrau­ matic routine. In 1960, shortly after the beginning of the epidemic, a rou­ tine of sterile atraumatic tracheotomy care was introduced3 (fig. 1). Fig. 2-Monitoring of tidal volumes and airway pres­ sures. Ventilation meter (1) and pressure gage (2) are placed temporarily be1ween nonrebreathing valve and tracheotomy tube during adjustment of Morch piston respirator.

ing exhalation if the expiratory pause at atmospheric pressure is at least as long as the inspiratory phase. 4. The respirator must function with room air and without carbon dioxide absorbents. 5. It must be simple and reliable in long term use, i.e., it must be "nurse proof." 6. It must deliver humidified air or a mixture of air and oxygen, with a relative humidity above 90 per cent at the tracheotomy tube; this is possible Fig. 1-Sterile tracheotomy care: (1) Catheter with curved tip inserted with forceps; (2) intermittent oc­ only with the use of specially heated clusion of T-tube for suction; (3) inner cannula with humidifiers. (The Morch piston respira­ swivel connector; (4) nonrebreathing valve; (5) tube tor, which normally does not come.with for inflation of cuff. a heated humidifier, had to be modi­ fied.) Respirators-Drinker tank respirators For most adult patients tidal .vol­ providing negative. and positive tank umes between 500 and 1,000 ml. of air pressures were used. The intermittent positive pressure respirators usually at a rate of 15 inflations per minute were modified Morch piston respira­ were required to prevent cyanosis and tors, 4 which proved reliable and sim­ to make the patient feel adequately ple. Other respirators are equally or ventilated. This amount of ventilation even more satisfactory, provided they is about twice that recommended by fulfil the following requirements: 1. the. Radford Nomogram. This hyper­ Ventilation must be adequate for .oxy­ ventilation usually caused arterial car­ genation and removal of carbon diox­ bon dioxide tensions between 20 and ide, even for patients with reduced 35 mm. of mercury. Normal ventilation lung-thorax compliance and· increased according to the Radford N omogram airway resistance; volume-set 'respira­ often provided normal c~rbon dioxide tors are more reliable in this respect tensions, but hypoxia was common. 1 than pressure-set respirators. 2. There must be means of monitoring tidal This suggests abnormality of i:he lungs volumes and airway pressures (fig. 2). with venous ~dmixture,. commoi;i i,n. pa­ 3. Peak airway pressures must be high tients treated by respirator. Therefore, enough to overcome increased pulmo­ in addition to hyperventilation i.t is nary resistance, but 'mean airway pres­ always advisable to increase the con­ sures should be as low as possible; this centration of inhaled ·oxygen of. the does not require a negative phase dur- respirator air to approximately 50 ·per 490 ARCHIVES of PHYSICAL MEDICINE & REHABILITATION Oct., 1962 cent during prolonged artificial venti­ Results lation. The results are summariz:ed in tables Apneic patients with poliomyelitis 1 and 2. In 1952, 1953 and 1955, 48 pa­ crave hyperventilation, even when car­ tients were treated with the tank res­ bon dioxide and oxygen values are pirator; most of them were tracheot­ normal. Therefore, complicated tech­ omized, and more than half of them nics for monitoring of blood gases are died during artificial ventilation. In rarely essential when deliberate mild 1960, 24 patients were treated by intra­ hyperventilation with 50 per cent oxy­ tracheal intermittent positive pressure gen is used. Hyperventilation was main­ ventilation; all of them had been tained for months with the patient re­ tracheotomized, and 17 per cent of maining conscious and showing no them died during artificial ventilation. signs of tetany. Deaths which occurred after the return Ventilation for Emergency Reoxygen­ of adequate spontaneous respiration are ation, Interval Ventilation and Trans­ not included in table 1. portation 5-Under emergency condi­ Table 2 indicates that in 1955 death tions the use of complicated equipment occurred during the acute phase of is not only cumbersome but dangerous. disease of all 5 adults who died. The The simplest and most versatile meth­ other 5 adults were discharged to a ods of reoxygenating the lungs of as­ respirator center after one or two phyxiated persons and for short term months, when they still required arti­ intermittent positive pressure ventila­ ficial ventilation Most patients treated tion are manual compression of a in the iron lung suffered from pul­ breathing bag or bellows or insuffiation monary complications which eventually of exhaled air (mouth to mouth or were lethal. Until 1956, almost all pa­ mouth to tracheotomy tube). tients who survived in the tank had to remain in it until discharge to a res­ The self-inflatin~ foam rubber bag de­ pirator center between one and three signed by Ruben or hand bellows do months later. not depend on a supply of compressed In contrast, in the 1960 series (table oxygen. Ventilation with the self-inflat­ 2) 14 patients regained adequate spon­ ing bag, which was connected via a non­ taneous respiration after intratracheal rebreathing valve to the tracheotomy intermittent positive pressure ventila­ tube, proved extremely simple and ef­ tion for periods ranging from two days fective whenever there was need for dis­ to three months. Twelve of these 14 continuing the respirator, e.g., during patients were discharged with adequate nursing care, service to the machine or spontaneous respiration. One patient, transportation of the patient to another a 22-year-old man, was breathing ade­ hospital. Long tubing between the bag quately and ready to be discharged, but and the nonrebreathing valve provided died suddenly during defecation (Val­ maximal flexibility during transporta­ salva maneuver) on the fifty-first day tion. Suction during transportation was after admission. Another patient, a 5- performed with a foot pump, which · year-old mongoloid boy, had regained does not depend on power supply or adequate spontaneous respiration after oxygen. three months of intermittent positive Whenever possible, transportation of pressure ventilation, but died of ful­ patients who require respiratory as­ minating bilateral pneumonia during sistance should be performed under the the fifth month after admission. supervision of an anesthesiologist, as­ Six patients were discharged to res­ sisted by a nurse. A regular ambulance pirator centers while they were still car is sufficient. Transportation in tank essentially apneic between 1 and 4V2 respirators requires a large team of months after admission. One of these experts, usually does not provide unin­ patients died in a tank respirator at terrupted adequate ventilation and is the respirator center. Four of these 6 unnecessarily cumbersome. patients regained some minimal breath- ARTIFICIAL VENTILATION-SAFAR, et al 491

Table 1: Poliomyelitis at Baltimore City Hospital Number of Patients

Deaths Mortality Bulbar and Prolonged During (%of Bulbospinal Artificial Artificial Respirator Total Paralysis Tracheotomy Ventilation Ventilation Patients) 1952* 137 25 5 5* 4 80 1953* 255 59 23 28* 13 46 1955* 129 12 15*(5 children; 8 (3 children; 53 10 adults) 5 adults) 1960t 88 43 25 24t(l0 children; 4 (3 children; 17 14 adults) 1 adult) *Tank respiration. tintermittent positive pressure ventilation with cuffed tracheotomy tube.

Table 2: Poliomyelitis at Baltimore City Hospital Duration of Artificial Ventilation

1955 1960 Tank Respiration lntratracheal Intermittent Positive Pressure Ventilation

Adults Children Period Result* Period Result* Period Result* 1 day Died 2 days S.R. 3 days S.R. 2 days Died 3 days S.R. 3 days S.R. 3 days Died 4 days Died 5 days S.R. 9 days Died 10 days S.R. 7 days Died 12 days Died 14 days S.R. 10 days Died 1 mo. R.C. 15 days S.R.t 11 days S.R. 1 mo. R.C. 16 days S.R. 11 days Died 1 mo. R.C. 24 days S.R. 1 mo. S.R. 2 mo. R.C. 1 mo. S.R. 3 mo. S.R.t 2mo. R.C. 1 mo. R.C. 4Yz mo. R.C. 3 mo. R.C.t (Adults only; data on children are 3Yz mo. R.C. not available) 3Yz mo. R.C. 4 mo. R.C. *S.R. indicates recovery with adequate spontaneous respiration; R.C. indicates discharge to respirator center with artificial ventilation. " tLate.death. ing movements, but still required re­ In some of these patients cardiac ac­ spiratory assistance one year later, I tion was restored by external cardiac child was still apneic I Y2 years later. massage. However, all of them died sub­ Four patients died during prolonged sequently. intratracheal intermittent positive pres­ The use of the tank respirator pro­ sure ventilation: vided adequate ventilation only when 1. A 35-year-old woman (E.M.) died soon after the airways were clear, the lungs and admission from what seemed to be circulatory thorax were compliant and there were collapse, inadequately treated, in spite of ade-. quate reoxygenation of the lungs. no significant leaks of air at the collar. 2. A 9.year-old boy (R.H.) was admitted with It often was difficult to provide a leak­ bilateral pneumonitis, large amounts of tracheo­ free seal of the collar of the tracheot­ bronchial secretions and bulbospinal paralysis. omized patient, particularly when the He died on the seventh day from what seemed neck was short. to be a combination of circulatory collapse and hypoxia due to pneumonitis. For patients with abnormal lungs and 3. A 3-year-old girl (V.T.) died from an un­ large amounts of tracheobronchial secre­ recognized obstruction of the tracheotomy tube. tions and for patients who were heavy This was an entirely preventable death. and obese, only intermittent positive 4. An 11-year-old boy (N.D.), admitted with pressure ventilation via tracheotomy tracheobronchial secretions and severe hyper­ thennia, died with signs of encephalitis, hyper­ provided adequate ventilation in the thennia and pneumonitis soon after admission. acute phase of the disease. For many pa­ The hyperthermia was inadequately treated. tients whose pulmonary condition de- 492 ARCHIVES of PHYSICAL MEDICINE & REHABILITATION Oct., 1962

teriorated while they were in the iron ease of patients treated by the latter lung in spite of tracheotomy, initial re­ means. There were 6 patients treated suscitation was possible by switching to by intratracheal intermittent positive positive pressure ventilation with a pressure ventilation who were still com­ breathing bag. pletely apneic after four months of arti­ The incidence of atelectasis was in­ ficial ventilation, while almost all pa­ creased during the use of the tank res­ tients who survived the acute phase in pirator, apparently because of difficulty the tank respirator had some sponta­ in changing the patient's position and neous respirations. in performing physical therapy, physical The safety of prolonged intermittent examination and roentgen examination. positive pressure ventilation lies in the Patients treated in the tank respirator following factors: (1) adequate ventila­ frequently required bronchoscopic as­ tion to keep the patient comfortable, piration. None of the adults treated by alert and well supplied with oxygen, (2) intratracheal intermittent positive pres­ meticulous tracheotomy care with ut­ sure ventilation required this. This dif­ most attention to both sterility and ference, we believe, was due to the avoidance of trauma; (3) maintenance routine of sterile and atraumatic tra­ of ciliary function by maximal humidi­ cheotomy care, the artificial coughing fication of the inhaled air with a heated and sighing maneuvers3 and the fact humidifier; (4) artificial sighing and that the positive pressure technic pro­ coughing maneuvers to counteract ate­ vides increased tidal volume. Prolonged lectasis; (5) frequent changes of posture ventilation with small tidal volume leads to prevent hypostatic pulmonary con­ to a reduction in lung compliance and gestion; (6) support of circulation, and atelectasis. (7) uninterrupted ventilation with Other disadvantages of the tank res- hand-operated equipment when the res­ . pirator are: (1) poor psychologic effect pirator is disconnected. on the patient, who feels as though en­ cased in a box; (2) difficulty in nursing Summary and Conclusions care, which leads to a higher incidence of pressure sores and phlebothrombosis; The use of the tank respirator should (3) difficulty in synchronizing the ma­ be reserved for the rare apneic patient chine with spontaneous respiration; (4) with "dry" lungs who does not need the patient's inability to talk in the tracheotomy. presence of a tracheotomy tube, and The principal advantages of intra­ (5) the high price. tracheal positive pressure ventilation The advantages of the tank respirator over tank respiration are greater ac­ over intratracheal intermittent positive cessibility and mobility of the patient pressure ventilation are: 1. The tank and the increased ventilatory reserve. can be used by patients who do not Intratracheal intermittent positive require tracheotomy, but these are pressure ventilation produces better exceedingly rare. 2. In the absence ventilation than tank respiration for of direct supervision, accidental inter­ · the patient with abnormal lungs and ruption of ventilation is less likely to the patient who is heavy and short. occur in the tank, since there is a pos­ sibility of accidental kinking or discon­ Acknowledgments: We thank Dr. D. Carrol for the performance of analyses of blood gas and Drs. nection of tubing of positive pressure T. DeKornfeld, L. Finberg and John Pearson for their help. ventilators. Obviously, with the use of School of Medicine either respirator a patient-triggered University of Pittsburgh Pittsburgh 13, Pa. alarm system should be provided. (Dr. Safar) Patients 'treated by intratracheal in­ termittent positive pressure ventilation References had a higher survival rate than those 1. Lassen, H. C. A.: Management of Life-Threat­ treated in the tank respirator, and this ening Poliomyelitis. Baltimore, Williams & was not due to increased severity of dis- Wilkins, 1956.