Management of Operations in the Pulmonary Cripple

Management of Operations in the Pulmonary Cripple THOMAS F. NEALON, JR., M.D., F.A.C.S.* ATHOLE G. McNEIL, M.B., Ch.B. **

Improvements in the management of thoracic surgical procedures now make it possible to operate on many patients with limited pulmonary capacity. Furthermore, the increasing prevalence of pulmonary emphysema presents the general surgeon with many more respiratory problems among his patients. These patients may have a pulmonary function which is barely adequate for everyday activities. Since most operations are associated with a transient depression of pulmonary function, the patient with little or no reserve capacity may be put in a critical situation postoperatively. With proper management most of these patients can be safely carried through the operations. 4 This involves maximal improvement of function preoperatively, proper anesthetic management, and attentive care of the patients postoperatively. It is our purpose to outline this management and to illustrate our points with pertinent case reports.

GENERAL CONSIDERATIONS Most operations, nonthoracic as well as thoracic, will produce some diminution in pulmonary function. This is only transient and can be expected to clear totally provided no pulmonary tissue is removed and thoracic mechanics are not impaired. Lower abdominal procedures will have the least effect. Upper abdominal procedures can cause severe impairment of chest movement, almost as severe as thoracic procedures which have the highest inci-

This work was supported in part by U.S. Public Health Service Grants HE-03349-09, HE-04486-06 and FR-72, and a grant from the Heart Association of Northeastern Pennsylvania *Professor of Surgery, Jefferson Medical College, Philadelphia, Pennsylvania **Associate Professor of Anesthesiology, Jefferson Medical College, Philadelphia, Pennsylvania ·

Surgical Clinics of North America- Vol. 47, No. 5, October, 1967

1224

THOMAS

F.

NEALON,

A THOLE G.

McNEIL

dence of pulmonary complications as direct involvement of lung tissue is added to the incisional pain. These complications are more severe and require longer to resolve than those resulting from pain alone. If any functioning lung is resected or if the chest wall or diaphragm is altered, some loss of function will be permanent. Complications that interfere with expansion of the lung or motion of the chest wall and/or diaphragm will also cause permanent loss of function.

PREOPERATIVE EVALUATION Preoperative evaluation of a patient with pulmonary insufficiency includes a careful history and good physical examination supplemented by a limited number of special studies of his pulmonary function. The history can be very valuable. Particular attention should be given to the patient's exercise tolerance, smoking habits, occupational history (particularly if exposure to dust is involved), presence of cough and its productivity, previous episodes or symptoms of congestive heart failure as well as the results of any previous illness or operation. All preoperative patients should have a complete physical examination with special attention given to the examination of the chest. The contour of the chest, its ranges of motion, its dependence on accessory muscles of respiration at rest, any changes in percussion note, the quality of breath sounds, and any adventitious sounds such as rales, rhonchi, or wheezes should be noted. Cyanosis or dyspnea at rest, while talking, and after mild exercise can be very informative. All other organ systems should be examined in the conventional manner, with special studies as indicated by the findings. Routine laboratory studies should include: complete blood count, urinalysis, electrocardiogram, and chest x-ray. Patients with a history of chronic illness, weight loss, or blood loss frequently have a diminished blood volume. Blood volume should be determined preoperatively in all these poor-risk patients. Any sputum produced should be cultured for bacteria and the antibiotic sensitivity determined. The extent of pulmonary suppuration can be evaluated by having the patient collect all his sputum in a cup left at the bedside. Quantity, consistency, and appearance of the sputum and changes therein from day to day give a basis for evaluating the effect of treatment. Pulmonary function studies need not be elaborate. Vital capacity, timed vital capacity, and maximal breathing capacity should be measured before and after a bronchodilator is administered by intermittent positive pressure breathing. The results after treatment will give an index of the improvement which might be achieved with proper preparation. Arterial blood gases and pH should be determined before and after exercise and after the use of a bronchodilator. The ability of the patient to blow out a match is another indication of his ability to move air. The studies listed above are sufficient for all general surgical procedures. In patients with pulmonary insufficiency requiring resection of pulmonary tissue, the functional contribution of the tissue to be removed must be assessed by bronchospirometry. This is the best

MANAGEMENT OF OPERATIONS IN THE PULMONARY CRIPPLE

1225

means of deciding whether the patient can tolerate the contemplated operation. Serum electrolytes should also be measured as a baseline before diuretic therapy or if prolonged postoperative intravenous therapy will be necessary.

PREOPERATIVE PREPARATION Preparation of the patient includes improvement of respiratory function with relief of bronchospasm and clearance of pulmonary infection. All smoking must be stopped. A history of heavy smoking (at least two packs of cigarettes a day) is of significance even in the patient who apparently has no pulmonary dysfunction. Substantial measurable improvement in pulmonary function usually results after smoking is stopped. All heavy smokers who must undergo a general anesthesia should stop smoking as soon as they enter the hospital. This not only facilitates anesthesia but it reduces postoperative complications. Patients with pulmonary suppuration should have postural drainage ten minutes four times daily. It is best to demonstrate the technique to the patients personally. Properly the patient is in a prone position and leans over the side of the bed so that only that portion of his body below his hips is on the bed. The remainder of his torso and head must be below the level of his hips. This is an uncomfortable position and should be timed by the clock rather than by the patient's sense of time to assure adequate performance. The sputum should be cultured and specific antibiotic therapy begun once the laboratory has identified the organisms and their sensitivities. Antibiotic treatment should be withheld until specific drugs can be administered. The quantity and consistency of the sputum for each 24-hour period should be noted. Satisfactory treatment results in an initial increase in volume but a decrease in consistency followed by a diminution in volume. All these patients should receive inhalation therapy. This consists of intermittent positive pressure breathing (IPPB) administered as often as is deemed necessary-usually for 20 minutes four times daily. The importance of using a gas mixture which has been warmed and humidified cannot be overstressed. To this basic regimen are added bronchodilators such as isoproterenol (lsuprel) or racemic epinephrine (Vaponephrin) to relieve the bronchospasm so commonly present in these patients. Such treatment should be continued for at least a week. Ideally the treatment should be continued until maximum improvement has been effected. This point is identified by periodically repeating the pulmonary function and blood gas studies. Obviously the point of maximal improvement cannot be identified until the curve of the improvement has leveled out. Although mucolytic agents are commonly used for removal of secretions, we have rarely found this necessary. Adequate hydration of the patient is as effective and when additional treatment is required we believe specific antibiotic therapy is far more helpful. Anemia should be corrected in hypovolemic patients by adminis-

1226

THOMAS

F.

NEALON,

A THOLE G.

McNEIL

tering whole blood; in the normovolemic, either by iron if operation can be delayed or, if not, by packed cells to avoid overloading the circulation. Patients with chronic pulmonary disease frequently have cardiac problems. These or other problems of any other system should be corrected as far as possible prior to operation.

OPERATION With modern anesthetic techniques, if the patient has been properly prepared for surgery as indicated above, the anesthetic management will usually be simple and the actual agents used need be no different from those in patients who are healthy. It is often advisable, however, to take some special precautions which are indicated by the pathologic findings in each case. In pulmonary surgery the use of one of the special endobronchial tubes such as the Carlens White or Gordon Green may be indicated so that there is control of individual areas of the lung and secretions can be isolated. Should this be unnecessary, or in patients who are to have abdominal surgery but in whom we might anticipate postoperative pulmonary complications, we use the largest possible cuffed nasa-endotracheal tube instead of the customary oral endotracheal tube as we find patients tolerate this better when they regain consciousness, and it can easily be used for at least the first few hours should supportive ventilation be necessary until the decision whether or not to do a tracheostomy is made. We have found that clinical appearance is not a good indication of satisfactory oxygenation and we therefore monitor arterial Po2 , Pco2 , and pH, 5 and we feel that one must be prepared to measure these parameters if one is going to operate on these patients. It could be argued that the routine use of a technique which permits high oxygen concentrations would avoid any desaturation and make such studies superfluous. This is not the case, for no matter how high the concentration of inspired oxygen, tbe Po 2 may be reduced. In addition, as blood gas studies are the only way to assess the patient postoperatively, the arterial cannula might as well be inserted at the beginning of surgery. In our experience changes in the blood gases have preceded changes in the vital signs usually monitored during operation. This practice has proved very helpful in picking up problems early, understanding their nature, and instituting proper treatment. We have seen changes in the blood gases occur as much as 45 minutes before changes in the usual vital signs. If induction of anesthesia causes a patient to develop bronchospasm and possibly cyanosis and hypotension which do not respond immediately to therapy, preparation has probably been inadequate. In that circumstance, the operation should be canceled. Furthermore, more intensive preparation will usually permit a later anesthesia without difficulty.

POSTOPERATIVE MANAGEMENT Immediately postoperatively all these patients require additional oxygen and some support of their ventilation; consequently most pa-

MANAGEMENT OF OPERATIONS IN THE PULMONARY CRIPPLE

1227

tients, and particularly those with inherent pulmonary disease, should have an oxygen-enriched atmosphere postoperatively. 2 A word of caution: Oxygen may be harmful rather than helpful, particularly in the patient with chronic respiratory insufficiency. The respiratory cripple may be cyanotic because of inadequate oxygenation but at the same time he may be developing hypercapnea for the same reason. The oxygen may satisfy his oxygen needs and knock out his only remaining respiratory stimulus (anoxia). Many patients with chronic respiratory insufficiency have lost their ability to respond to hypercarbia. Consequently, when sufficient oxygen is available there is no stimulus to respiration; carbon dioxide accumulates and respiratory acidosis ensues. If oxygen is used alone, the patient must be watched carefully for signs of the development of C0 2 narcosis- a rise in pulse and blood pressure and drowsiness. If this occurs several therapeutic possibilities are available: (1) continuous oxygen with continuous ventilatory support; (2) continuous oxygen with frequent periodic IPPB (q 2 to 4 hours around the clock); (3) no oxygen but periodic IPPB. Prophylactic postoperative therapy is directed primarily at the prevention of hypoventilation and atelectasis. 3• 6 Frequent deep breathing, periodic coughing, and early ambulation are necessary. Sufficient analgesics to relieve pain will help the patient to carry out these exercises. A patient is far more likely to cough satisfactorily if his pain is controlled. Concern that narcotics will depress the cough reflex and promote the accumulation of secretions is often overdeveloped. These results occur only if sufficient narcotics are given to render the patient stuporous. A conventional dose can be very dangerous in a seriously ill patient, however. Consequently, in such a patient it is best to begin with quantities less than usual and to supplement them if necessary. Intermittent positive pressure breathing is used regularly in these patients to prevent hypoventilation, accumulation of secretions, and atelectasis. In spite of good care, secretions may continue to accumulate. In these cases a tracheobronchial toilet should be carried out. A sterile suction catheter is passed through the nose into the trachea and the resulting stimulation of the carina will produce coughing which will help expel material from the smaller bronchi. If the secretions are tenacious, 2 to 3 ml. of physiologic salt solution passed through the tube helps to loosen them. The danger of this form of toilet is that the catheter will aspirate the oxygen as well, raising the possibility of cardiac arrest. 7 A more ideal method would be to pass a nasal endotracheal tube each time. Through this, repeated suction can be carried out, alternating short periods of aspiration with short periods of ventilation using such equipment as an Ambu Bag. In this way, maximum aspiration can be achieved with minimum risk. If the nasal mucosa is desensitized with a local anesthetic agent such as 4 per cent lidocaine (Xylocaine) this is also less painful than repeated passage of a suction catheter. If the patient's respiratory problems persist with the above regimen, bronchoscopy is indicated and can be performed at the bedside with

1228

THOMAS

F.

NEALON,

A THOLE G.

McNEIL

minimal difficulty. It is well to culture the aspirations and obtain antibiotic sensitivities on any bacteria obtained. A tracheostomy should be performed if repeated bronchoscopies are needed to remove excess secretions. Tracheostomy should be elected before the patient becomes preterminal from the hypoxia and hypercapnea. This decreases the physiologic dead space, but more importantly simplifies aspiration of the tracheobronchial tree. Continual good hydration of the patient at all times in the postoperative period will help to loosen the bronchial secretions. Some surgeons insert a fine polyethylene catheter percutaneously via a needle through the cricoid cartilage into the trachea. 6 Coughing is stimulated and secretions cleared by the direct installation of small amounts of saline, bronchodilators, antibiotics, and/or enzymes into the trachea. We have not found it necessary to use this technique. All patients who require inhalation therapy preoperatively as well as those who are in respiratory difficulty postoperatively should have inhalation therapy postoperatively. Prophylactically a schedule similar to that used preoperatively is usually adequate. When used therapeutically it can be employed much more frequently, even continuously. The patient may be unable to move sufficient air to ventilate his lungs properly, or the effort required to do this may be exhausting to him. If he continues under these circumstances he will go into a generalized collapse and succumb. This can be prevented by providing the patient with adequate ventilation until he can breathe well for himself. This technique is described in detail elsewhere in this symposium.

ILLUSTRATIVE CASE REPORTS CASE 1. C. K., a 39-year-old housewife, was admitted to JMCH for treatment of a large substernal thyroid. On admission the patient, who had a long history of pulmonary emphysema, was markedly short of breath. Sitting in bed she could barely talk because of her dyspnea. Her thyroid was markedly enlarged with the left side the more pronounced. Inspiratory and expiratory fine rales could be heard in both lung fields but were more pronounced at the bases. Wheezes and rhonchi could be heard throughout both bases. Chest x-ray demonstrated displacement of the trachea to the right due to a mass lesion at the level of the thoracic inlet, thought to be due to thyroid enlargement. The lung fields were clear (Fig. 1). Pulmonary function studies demonstrated a vital capacity of 49 per cent of the predicted 2797 cc. and a maximum voluntary ventilation 32 per cent of the 92 L/M predicted. Bronchodilators did not produce any appreciable change in these values (Table 1). These studies seemed to suggest that little improvement could be expected. However, a course of pressure breathing gave her considerable symptomatic relief. Serial function studies showed a gradual improvement in vital capacity from 49 per cent to 70 per cent over a 2-week period. These are listed in detail in Table 1. Thyroidectomy was performed under endotracheal ether oxygen anesthesia on October 25, 1966. Arterial blood gases were analyzed periodically during the operation and in the early postoperative period and we were prepared to institute continuous ventilatory support if necessary. However, there was no need for this. She did well during operation. The Po2 arid Pco 2 of her arterial blood remained within normal limits during operation. Furthermore, she was able to maintain

a::

z> ~ m

:::m

z.., 0

"1

Table 1. Pulmonary Function Studies in Case 1 10/10/66

10/3/66 BEFORE BRONCHODILATOR

10/17/66

10/31/66

AFTER BRONCHODILATOR

Pred.

Ob.

%Pred.

Ob.

2797

1452

49%

1474

92

32

35%

29

0.., m ..,~

0 zrJl

..,z

Ob.

% Pred.

Ob.

% Pred.

Ob.

% Pred.

:t

49%

1748

59%

2075

70%

2370

80%

"0

32%

34

37%

42

45%

54

59%

8z

% Pred.

m

Vital capacity Maximum voluntary ventilation (L/M) Forced expiratory volume 1 second 2 seconds 3 seconds Maximum midexpiratory flow rate (LiM) Maximum expiratory flow rate (L/M)

67% 85% 95%

76% 96% 100%

70% 86% 94%

78% 92% 97%

77% 92% 97%

c:t"'

>

~

n

38

54

71

62

122

..,..,~

25

27

69

107

154

m

t"'

.....

N N

cc

1230

THOMAS

F.

NEALON,

A THOLE G.

McNEIL

Figure 1. Admission x-ray of the chest in Case 1. The trachea is displaced to the right by a mass at the level of the thoracic inlet.

these values without ventilatory support during the early postoperative period. On the second postoperative day, she had difficulty with retained secretions which cleared readily following bronchoscopy. The only ventilatory support she received was IPPB 20 minutes q.i.d. She left the hospital 6 days after operation. Another function study done on the day of discharge demonstrated further improvement (Table 1). Furthermore, her Po2 while breathing room air which was 84 mm. Hg preoperatively had risen to 93 mm. Hg under similar circumstances at the time of discharge.

Comment. This is an example of the value of good preoperative management in preparing a patient with pulmonary insufficiency for operation. She could not have tolerated any type of general anesthesia when she first entered the hospital, yet after preparation she did very well. Since the operation in no way interfered with function of her lungs she readily returned to her preoperative status. Her postoperative convalescence was no different from that of the average patient. Ideally the preparation should have continued longer before the operation. The final preoperative study demonstrated continued improvement. Preparations should have continued until the improvement had leveled_out. TP.is is· further substantiated by the additional improvement after operation. · CAsE 2. A 62-year-old man was transferred to JMCH on July 15, 1966 from another hospital. Eighteen months earlier a diagnosis of advanced emphysema had been made and he was started on IPPB at home. He had been hospitalized for the previous 2 weeks with shortness of breath and abdominal complaints. Changes in his right lung (Fig. 2, A) were diagnosed as pneumonia. He was given penicillin, continuous oxygen, and started on IPPB. He had been admitted there with lower abdominal pain. He developed abdominal distention which responded to intestinal intubation but recurred each time the tube was removed and an effort was made to feed him. During his hospital stay he became progressively confused and lethargic. He was transferred to Jefferson because of a new development of right upper quadrant pain and tendemess.

MANAGEMENT OF OPERATIONS IN THE PULMONARY CRIPPLE

1231

Figure 2. X-rays of the chest in Case 2. A, Eighteen months prior to admission. B, On admission and C, at discharge. The fluid present on admission (B) had cleared by the time of discharge (C). (From Pennsylvania M. J. 69:49, 1966.)

On arrival under continuous oxygen he was markedly lethargic. There was diminution of breath sounds throughout his chest, and generalized wheezing. There was flatness of percussion over his lower right lung field. His abdomen was slightly distended with tenderness and guarding in the right upper quadrant. Chest x-ray demonstrated generalized advanced emphysema and a pleural effusion of the right base (Fig. 2, B). X-ray of the abdomen showed enlarged loops of small bowel (Fig. 3). He was prepared with IPPB 20 minutes every t_wo hours around the clock with a marked clearing of his sensorium. On the fourth hospital day, laparotomy revealed an empyema of the gallbladder and a partial small bowel obstruction due to involvement in an appendiceal abscess. A cholecystectomy accompanied by appendectomy was performed. He tolerated the operation without difficulty and responded well while in the operating room. In the recovery room his Pco 2 began to rise and a cuffed nasotracheal tube was inserted and attached to a respirator. This readily corrected the blood gas values. Ventilation was continued without interruption overnight. The tube was removed the following day. He was put on continuous oxygen and on IPPB 20 minutes every 2 hours around the clock. The Pco2 ranged between 46 and 56. The frequency of treatment was gradually decreased with no deleterious effect on his breathing or his blood gases. It was possible to discontinue the continuous oxygen on the third day. At the time he left the hospital on the seventeenth postoperative

1232

THOMAs

F.

NEALON,

A THOLE G.

McNEIL

Figure 3. Abdominal film in Case 2 showing distended loops of small bowel. (From Pennsylvania M. J. 69:49, 1966.)

day he was able to resume normal activity without dyspnea, using IPPB four times daily. An x-ray of his chest showed that most of the fluid had resorbed (Fig. 2,C).

Comment. l'his patient arrived at our hospital in carbon dioxide narcosis because of injudicious use of oxygen. The oxygen therapy was emphasized while the ventilatory support (IPPB) although ordered was not pushed. This allowed carbon dioxide to accumulate and narcosis to develop. At that time his pulmonary problems were complicated by pulmonary infection and pleural effusion probably secondary to his intra-abdominal sepsis. In many patients with a similar problem, a tracheostomy and continuous ventilatory support would probably have been necessary postoperatively. It was avoided in this case because of the effective use of the IPPB. This was possible because the patient was an intelligent individual who had long experience with the apparatus. He needed ventilation more than he needed oxygen. The IPPB provided sufficient assistance until his function improved. Stopping the continuous oxygen early in the postoperative period also helped to hold the carbon dioxide level down. CASE 3. L. T., a 59-year-old retired foundry worker, was admitted to JMCH on October 10, 1965 for treatment of a large mass in his left lung. He had a chronic cough for many years. He recently developed hemoptysis and was bril!ging up 2 ounces of sputum daily. He had a limited exercise tolerance for several

MANAGEMENT OF OPERATIONS IN THE PULMONARY CRIPPLE

1233

years and in recent months had several bouts of pneumonitis. He had lost 25 pounds over the previous several years. On admission he was a thin male with dyspnea on any exertion. His chest had an emphysematous contour. He had diminished breath sounds at his left base and wheezes throughout both lungs. X-ray of the chest (Fig. 4, A) demonstrated fibrosis and emphysema throughout both lung fields and a mass with an air fluid level in the midportion of the left lung. Bronchoscopy revealed a mass protruding from the bronchus to the superior segment of the left lower lobe, which on biopsy proved to be a squamous cell carcinoma Pulmonary function studies revealed a maximal breathing capacity (MBC) of 45 per cent of predicted, which improved to 65 per cent of predicted following the use of IPPB with a bronchodilator. The patient was started on a course of postural drainage, inhalation therapy and antibiotics. Some clinical improvement occurred at once but his course was punctuated by episodes of respiratory infections. After a month of therapy his MBC had improved only to 50 per cent. It was felt that the improvement accomplished by the treatment had been offset by an increase in the size of the tumor and repeated episodes of pneumonitis caused by spill of secretions. It was decided that maximal benefit had been attained and that operation should be undertaken with the full realization that he was going to require intensive care postoperatively. A left pneumonectomy was performed on November 15, 1965. He did well until after his bronchial stump had been closed when his condition deteriorated and his blood pressure fell. An arterial blood sample showed a Po2 of 68, a Pco2 of 80 and a pH of 7.13. The ventilation was markedly increased and he was given a small amount of ephedrine. His blood pressure responded and his color improved. At this point his Po 2 had risen to 150, his Pco2 had dropped to 45, and his pH had risen to 7.34. As soon as the operation was completed a tracheostomy was performed and he was attached to a mechanical ventilator for continuous ventilatory support. His condition stabilized. He was kept on continuous ventilator support for 5 days. During this time his Po2 and Pco2 remained within normal limits. He was then switched to an oxygen collar and frequent IPPB and this was gradually decreased until he was able to be active about the hospital using the IPPB 20 minutes four times daily. At the time of discharge, on room air, he was maintaining a Po2 of 70 mm. Hg and a Pco 2 of 35 and a pH of 7.46. The patient retumed for a follow-up examination 11 months after operation. He was without dyspnea and had not used the IPPB for 3 months. Without inhalation therapy his Po2 while breathing room air was 93 mm. Hg. There was no evidence of recurrence of his disease (Fig. 4, B).

Comment. Good care at all phases of his hospitalization was necessary to get this man home well. Monitoring his blood gases during operation made it possible for us to treat his collapse properly and promptly. If we had assumed that the collapse was due to blood loss and had overtransfused him we could have caused him serious harm. He would not have survived had it not been possible to give him continuous ventilatory support for several days immediately postoperatively. His improvement after he left the hospital was most pleasing and totally unexpected. We thought he had attained most of his postoperative recovery before he left the hospital. It may be that the repeated aspiration pneumonias caused changes which were very slow in resolving. This man was probably as ill as any one on whom we would attempt such management. We were willing to try it only because we had seen how these supporting measures can help these patients.

1234

THOMAS

F.

NEALON,

A THOLE G.

McNEIL

Figure 4. X-rays of the chest in Case 3. A, Upon admission there is fibrosis and emphysema throughout both lung fields and a mass with an air-fluid level in the midportion of the left lung. B, Eleven months after operation. There is some overdistention of the remaining lung but no evidence of recurrence of his carcinoma.

SUMMARY Most patients with respiratory insufficiency can be carried through any general surgical procedure and many thoracic procedures with proper management. This begins with therapy in the preoperative period, with cessation of smoking, periodic pressure therapy (IPPB), bronchodilators, tracheal toilet, and specific antibiotic therapy. Management during anesthesia is simplified for the anesthesiologist when the patient has been properly prepared. In the postoperative period, hypoventilation with accumulation of secretions and C02 must be prevented. Frequently oxygenation and ventilation must be augmented. Such patients are best cared for in a special unit but can be treated in any general hospital by a staff with special training who have a blood gas laboratory available.

REFERENCES 1. Fineberg, C., Cohn, H. E., and Gibbon, J. H., Jr.: Cardiac arrest during nasotracheal aspiration. J.A.M.A. 174:410, 1960.

2. Heller, M., and Watson, T. R.: Postoperative hypoxemia and its treatment with nasal oxygen. Surgery 58:819, 1965. 3. Loftrom, B., and Pemow, B.: Postoperative pulmonary complications. Acta Chir. Scand. 129:395, 1965. 4. Nealon, T. F., Jr., McNeil, A. G., and Prorok, J.: Respiratory insufficiency in surgery. Pennsylvania Med. 69:49, 1966. 5. Nealon, T. F., Jr., Prorok, J., Gostin, S., and Fraimow, W.: Impaired oxygenation with prolonged continuous ventilatory support. Ann. Surg. 164:558, 1966. 6. Siger, J., Frederick, P., and Osborn, M.: Prevention of postoperative pulmonary complications by percutaneous endotracheal catheterization. Surg. Gynec. & Obst. 123:336, 1966. 1025 Walnut Street Philadelphia, Pennsylvania 19107