Surgical Advantages of Selective Unilateral Ventilation

Transcription

1 Surgical Advantages of Selective Unilateral Ventilation Richard E. Wood, M.D., Donovan Campbell, M.D., Maruf A. Razzuk, M.D., Donald L. Paulson, M.D., and Harold C. Urschel, Jr., M.D. ABSTRACT Two hundred major thoracic operations have been performed using controlled selective unilateral pulmonary ventilation with no morbidity or mortality related to this technique. A group of 20 patients ventilated selectively with a double-lumen endotracheal tube and 5 additional patients ventilated with a single-lumen tube were studied to determine the physiological effects of each technique. Blood gases and physiological shunt determinations showed better values with selective ventilation, whereas some derangement was noticed in the group ventilated with a single-lumen tube. The physiological and technical advantages provided by the double-lumen endobronchial tube make selective ventilation safer and more practical. S elective unilateral pulmonary ventilation with a double-lumen endobronchial tube provides several technical advantages over the standard single-lumen tube ventilation. These include improvement of surgical exposure, unilateral cessation of respiratory and diaphragmatic excursions, safe inspection of the open bronchus, selective deflation and inflation of the lung, and prevention of transbronchial spread of purulent secretions or blood. No untoward physiological effect has been observed with this technique, and the patient is maintained in satisfactory homeostatic balance. The efficiency of ventilation is demonstrated by the stable normal values of blood gases throughout the operative procedure. Comparable values of blood gases have been found to be moderately deranged with the single-lumen endotracheal tube ventilation as compared with unilateral selective ventilation. The purpose of this paper is to present the technical advantages and emphasize the physiological safety provided by the use of selective unilateral pulmonary ventilation in thoracic operative procedures. Clinical Data Two hundred major thoracic operations have been performed under general anesthesia with 1 or 2% halothane and oxygen employing a semi- From the Departments of Thoracic Surgery, Baylor University Medical Center and the University of Texas Southwestern Medical School, Dallas, Tex. Presented at the Eighth Annual Meeting of The Society of Thoracic Surgeons, San Francisco, Calif., Jan , Address reprint requests to Dr. Wood, 3810 Swiss Ave., Dallas, Tex VOL. 14, NO. 2, AUGUST,

2 WOOD ET AL. closed system without the use of muscle relaxants or barbiturates. Selective unilateral ventilation was used in all patients with no related morbidity or mortality. The double-lumen tube used in this study was introduced by Robertshaw [8]. t is made of rubber and is designed for right and left bronchial intubation. The left tube is angled 45 degrees at the tip and is provided with both endotracheal and left main bronchus cuffs, while the right lumen terminates just above the carina (Fig. 1). When the left bronchial and endotracheal cuffs are inflated, the right lumen communicates only with the right main bronchus. The right-sided tube has a tip angled 20 degrees to enter the right main bronchus and has a slotted endobronchial cuff to permit inflation of the right upper lobe (Fig. 2). Twenty consecutive patients, 12 men and 8 women ranging in age from 17 to 71 years, have been evaluated to determine the physiological status of unilateral ventilation. Five additional patients ventilated by the single-lumen endotracheal tube were evaluated in the same manner. All patients had preoperative pulmonary function studies and arterial blood gas determinations. Operative blood gases with the patient in the lateral decubitus position were obtained just before the start of unilateral ventilation, at intervals of 15, 45, 1 2 FG. 1. The position of u left-sided double-lumen endobronchial tube, which is used in right thorucotomies. FG. 2. A right-sided double-lumen tube with slotted cuff positioned in the right bronchus for selective ventilation, which is used for left thorucotomies. 174 THE ANNALS OF THORACC SURGERY

3 Selective Unilateral Ventilation and 75 minutes after its initiation, and at the conclusion of the operation after the bronchial cuff had been deflated. Blood gases were also determined at the same time intervals in patients ventilated with the standard singlelumen endotracheal tube. Blood samples were withdrawn with the patient breathing 100% oxygen for a period of 5 to 10 minutes. R esu 1 ts Blood gas values in the group ventilated by the selective unilateral technique remained practically stable throughout the procedure with no significant deviation from the preocclusion values except, however, for a moderate decrease in p02 (Figs. 3-5). The blood gases in the group ventilated by the single-lumen tube technique showed variation between the preoperative and operative values with a definite increase in the pc02 and decreases in ph and p02 (Figs. 3-5). The degree of physiological shunting, which ranged preoperatively between 0.3 and 8% with a mean of 3.3%, corresponded closely with the pulmonary function. The intraoperative shunt before thoracotomy was nearly five times greater than the preoperative value and rose slightly during the period of anesthesia (Fig. 6). Comment Bjork and associates [2] in 1953 reported selective unilateral ventilation with the Carlens double-lumen bronchospirometry tube. Several modifications of this tube have been described [2, 3, 6, 8, 91. The tube used in this study is that improvised by Robertshaw [8] in t is made of rubber and is available in sizes small, medium, and large, corresponding with the Magill endotracheal tubes sized 8, 10, and 12. The large internal lumen of this ( rn in 1. d DURAllON FG. 3. Graphic comparison of mean PO, values for both tubes. Note the drop in PO, of the single-lumen tube (dotted line) as compared with the double-lumen tube (solid line). VOL. 14, NO. 2, AUGUST,

4 WOOD ET AL. 35 PRE-THollpcOroMY OPERATVE CLOSURE (minuter) DURATON FG. 4. Graphic comparison of mean pc0, values for both tubes. Note the elevated values with the single-lumen tube (dotted line) as compared with the double-lumen tube (solid line). tube provides decreased airway resistance and permits easy aspiration of endobronchial secretions. Both right and left tubes are available with angulated tips of 20 and 45 degrees, respectively, for endobronchial intubation. This option to use tubes for the right or left side is of particular value in doing pneumonectomies and in handling patients with obstructions of the main bronchi. The anesthetic technique employed in this series consisted of the administration of 1 to 2% halothane in oxygen for both induction and maintenance throughout the procedure. No muscle relaxants or barbiturates were given pn PRE-lHO(ACOlOMY OPERAT VE (minutes) D URAT ON FG. 5. Graphic comparison of mean PH values for both tubes. While the values of the double-lumen tube (solid line) remain stable and within physiological range, those of the single-lumen tube (dotted line) show definite derangement. 176 THE ANNALS OF THORACC SURGERY

5 Selective Unilateral Ventilation Percent of 15 Physiological Shunt 10 5 RE minyt., ) DURATON FG. 6. Graphic comparison of mean physiological shunts for both tubes. Slightly higher values are observed with the single-lumen tube (dotted line) than with the double-lumen tube (solid line). The use of selective unilateral ventilation by means of the double-lumen endobronchial tube in major thoracic procedures provides many technical and physiological advantages over the standard endotracheal tube. t prevents transbronchial contamination by purulent materials or necrotic debris that might gravitate from the operated lung into the opposite, dependent site, which is likely to occur in patients with cavitary tuberculosis, chronic lung abscesses, suppurative cavitating bronchogenic carcinoma, or saccular bronchiectasis. The unilateral collapse of the operated lung improves surgical exposure and shortens the duration of operation as a result of cessation of pulmonary and diaphragmatic movements. The deflated lung can be selectively inflated when lobar or intersegmental resection is performed in order to facilitate delineation of the anatomical planes. Open inspection and aspiration of the bronchus can be safely done without interrupting ventilation. This technique obviates the necessity for cross-clamping the proximal bronchus, which is of particular benefit when performing bronchotomies, bronchoplastic procedures, or pneumonectomies. The quiet operative field afforded by this technique is of great help in esophageal resections and repair of diaphragmatic hernia. Selective unilateral ventilation also provides physiological advantages over single-lumen tube ventilation because it effects better ventilation of the dependent lung, which has greater perfusion than the contralateral side. t has been shown by radioactive isotope studies (xenon 133) that distribution of pulmonary blood flow varies with body position, with the most dependent portion receiving the greatest flow [71. This phenomenon is due mainly to gravity [l, 5, 81, although Pain and West [7] showed that blood flow is higher in the expanded lung than when it is deflated. This presumably VOL. 14, NO. 2, AUGUST,

6 WOOD ET AL. was the effect of change in the surface tension of the alveolar lining altering the pericapillary pressure. That physiological advantages are provided by controlled selective ventilation is supported by the results of blood gas tests obtained in this study. The ph, p02, and pc02 were stable throughout the procedure in patients having selective ventilation, without any significant deviation from the preoperative values. However, these same values showed definite derangement in patients ventilated by means of the single-lumen endotracheal tube. The ph and p02 were decreased, and the pc02 was increased. Although the physiological shunting was five times greater with both techniques during the operative procedure as compared with preoperative values, lower values were observed with selective ventilation. The physiological and technical advantages provided by the doublelumen endotracheal tube make selective unilateral ventilation a safer and more practical method of ventilation in major thoracic operative procedures. References 1. Anthonisen, N. R., Dolovich, M. B., and Bates, D. V. Steady state measurement of regional ventilation to perfusion ratios in normal man. J. Clin. nvest. 45: 1349, Bjork, V. O., Carlens, E., and Friberg, 0. Endobronchial anesthesia. Anesthesiology 14:60, Bryce-Smith, R. A double-lumen endobronchial tube. Br. J. Anaesth. 31:274, Campbell, E. J. M. Respiration. Ann. Rev. Physiol. 30:105, Fishman, A. P. Regulation of pulmonary circulation. Physiol. Rev. 41:214, Madntosh, R., and Leatherdale, R. A. L. Bronchus tube and bronchus blocker. Br. J. Anaesth. 27:556, Pain, M. C. F., and West, J. V. Effect of the volume history of the isolated lung on distribution of blood flow. J. Appl. Physiol. 21:1545, Robertshaw, F. L. Low resistance double-lumen endobronchial tubes. Br. J. Anaesth. 34:576, White, G. M. J. Evolution of endotracheal and endobronchial intubation. Br. J. Anaesth. 32:235, Discussion DR. RAYMOND C. READ (Little Rock, Ark.): agree completely with the authors: operation on the quiet lung offers many advantages. Why haven t more surgeons adopted this technique, especially since unilateral ventilation was recommended for routine use in thoracic surgery back in 1958 by Jenkins and Clark in England and three years later in this country by Newman, Finer, and Downs? Togelher these two groups reported a satisfactory experience with 500 patients. believe there have been two factors holding up the widespread acceptance of this technique. First, anesthesiologists find double-lumen tubes a little more difficult to handle than standard endotracheal tubes. Dr. Wood and his colleagues have elicited excellent cooperation from their anesthetists, thus eliminating this problem. The second objection is more serious. Does total collapse of one lung lead in certain patients to arterial oxygen desaturation from venous admixture? 178 THE ANNALS OF THORACC SURGERY

7 Selective Unilateral Ventilation The authors assert on the basis of their average arterial poz values that when 100% oxygen is used for ventilation, this hypoxia is eliminated. agree that for most patients this is true. We have found, however, in agreement with isolated reports in the literature, that in a minority of approximately 15% of patients the arterial poz falls to 70 mm. Hg or below. There is such great variability from individual to individual, presumably related to distribution of disease and hemodynamics or ventilatory factors, that we have been unable to select out such persons. n 39 patients we found that the arterial poz during administration of 100% oxygen ranged from 58 to 304 mm. Hg and averaged 179 during unilateral ventilation. The highest value occurred in a patient undergoing pneumonectomy in whom the pulmonary circulation to the collapsed lung had presumably already been eliminated. would like to know the lowest arterial PO, values observed by the authors during lung collapse. Finally, the authors, as a result of their studies, seem to have reached a remarkable conclusion-that a patient is better ventilated when one lung is totally collapsed than when one lung is partially compromised. Such a finding is dramatically opposed to that reported in separate investigations from Sweden and the Mayo Clinic. t seems too good to be true. Another interpretation of their data is, believe, more likely. The control group of 5 patients undergoing pulmonary resection in the conventional manner were underventilated and therefore atypical. Thus their average poz on 100% oxygen fell drastically to 165 mm. Hg, their pcoz rose to about 50, and the ph was only Our own work has been in the direction of trying to eliminate the occasional case of hypoxemia. We have monitored these patients arterial poz so that we can recognize when the lung is collapsed. One patient, for instance, a 55-year-old man, had a right upper lobectomy, and his poz fell to 72 mm. Hg. We then clamped the main pulmonary artery to the right lung during the resection, and his poz instantly rose to very reasonable levels. We believe that if one maintains the possibility of clamping the inflow of the lung, the potential hazard in a few patients of a large shunt leading to low poz levels can be eliminated. DR. NCHOLAS J. DEMOS (Jersey City, N.J.): Our experimental and clinical studies of unilateral pulmonary ventilation started fifteen years ago at Northwestern University with Dr. F. John Lewis and were reported in the older sister association. The purpose of our work was to achieve a bloodless operation in a quiet field through concomitant bronchial as well as vascular occlusion. All dogs that were operated upon had long survival following as much as 90 minutes of normothermic or two hours of hypothermic hilar occlusion, even after contralateral pneumonectomy. Thus we established the safe limits of bronchial and vascular hilar occlusion. We applied this technique successfully in more than 40 patients without major complications and with only slightly prolonged postoperative air leakage from the raw lung surface, compared with that following the usual massive clamping and suturing method. The concomitant vascular occlusion added to the bronchial occlusion is necessary to avoid the overwhelming physiological shunt produced by bronchial occlusion alone. t is well known that general anesthesia by itself decreases the ventilation-perfusion ratio. f one adds the atelectasis of one entire lung, the shunt assumes tremendous proportions. n spite of the good blood gas values in the authors patients, would be hesitant to use this method routinely. would recommend limiting the indications to selected patients such as those with bullous emphysema or arteriovenous fistula or certain patients with tuberculosis. f one has to use it, would recommend concomitant vascular occlusion added to the bronchial occlusion in order to avoid excessive physiological shunting.

8 WOOD ET AL. DR. WOOD: The technical advantages of selective unilateral ventilation by a double-lumen endotracheal tube (Robertshaw) in more than 200 patients undergoing thoracic procedures without operative mortality or morbidity have been reported. n this series, temporary ipsilateral pulmonary artery occlusion has not been required to maintain a stable physiological state, although arterial gas monitoring should be utilized until one is familiar with selective unilateral ventilation and in all gravely ill patients. ntubation and positioning of the Robertshaw tube are performed by standard anesthetic techniques, enabling most anesthesiologists to employ this type of anesthesia. 180 THE ANNALS OF THORACC SURGERY