History and Scope of Anesthesia for Thoracic Surgery

Marcelle Blessing
Edmond Cohen

The history of anesthesia for thoracic surgery encompasses much of the history of anesthesia because the modern practice of thoracic anesthesia relies on major advances in preoperative evaluation, airway management, intraoperative monitoring, pharmacological agents, and improvements in postoperative pain management and intensive care management. These advances equip the modern thoracic anesthesiologist with the tools and techniques to care for even the frailest patients undergoing complex surgical operations. Many patients who would have been deemed inoperable in the past are operative candidates today, because of improvements in both anesthetic and surgical techniques that have augmented safety for all patients undergoing thoracic surgery. The current practice of anesthesia for thoracic surgery represents a culmination of 100 years of advances in anesthesia techniques, and these techniques continue to evolve.

THE EARLY YEARS OF THORACIC SURGERY

The safe delivery of anesthesia for thoracic surgery is a relatively late development in the history of anesthesia because of the ingenuity needed to overcome the unique challenges of safely performing surgery in the thorax. It is easy to forget today that prior to advances in general anesthesia techniques, specifically positive pressure ventilation and controlled respiration with endotracheal intubation, surgery that trespassed the chest wall posed grave risks to patients. Although inhalational anesthesia was introduced in the 1840s, it took another 100 years before anesthesiologists made significant headway in providing safe care for patients undergoing operations in the chest. Improvements in anesthetic practice permitted thoracic surgery to flourish as a specialty; the growth of no other surgical subspecialty depended so heavily on the progress of anesthesia. Although intrathoracic procedures have become routine, thoracic surgeons and anesthesiologists retain a unique relationship; few areas of surgery require as much communication and cooperation between surgeon and anesthesiologist.

As the scope of thoracic surgery has increased greatly, so has the scope of anesthetic practice for it. Today, knowledge of anesthesia techniques for thoracic surgery has become more important than ever. Greater numbers of and types of procedures for lung, esophageal, mediastinal, anterior and posterior spinal, thoracic aortic and cardiac surgery rely on thoracic approaches that require use of one-lung ventilation (OLV). Also, more intrathoracic procedures are being performed with minimally invasive approaches that rely on OLV for adequate surgical exposure. To safely provide the OLV that is universally favored by thoracic surgeons, anesthesiologists must be knowledgeable about the physiology of OLV, be familiar with the range of tools available for providing it, and be aware of techniques for preventing hypoxemia. A variety of double lumen endotracheal tubes and modern endobronchial blockers are now available to provide safe and reliable OLV for most patients.

The Pneumothorax Problem

The inherent danger of performing surgery within the thorax has been known since antiquity. Almost 2000 years ago, the Roman encyclopedia author Celsus, in De Medicina, described the problem succinctly by noting that when a knife penetrates the chest death ensues at once, even though the belly can be opened safely with the patient breathing spontaneously.¹ Celsus was describing the so-called “pneumothorax problem”: When the chest is opened and the lung is exposed to atmospheric pressure, the operative lung suddenly collapses because of the loss of the normally negative intrapleural pressure. The collapsed lung would paradoxically expand during expiration and collapse again during inspiration, as air was transferred from healthy to collapsed lung by the patient struggling to breathe. The transfer of air between the two lungs became known as “pendelluft.” A surgeon brave enough to open the chest wall of a spontaneously breathing patient would also face vigorous side-to-side movement of the mediastinum with respiration known as “mediastinal flapping” that would cause compression of the contralateral lung. The patient would quickly become tachypneic and cyanotic while struggling to breathe spontaneously. Only the briefest intrathoracic procedures could be performed under these circumstances, and for this reason thoracic surgery was mostly limited to procedures of the extrathoracic chest wall in the first third of the 20th century. John W. Strieder, an eminent thoracic surgeon, gave a colorful description of operating in the “good old days” where “the period of operation was, with dismaying frequency, a race between the surgeon and the impending asphyxia of the patient.”²

After the advent of inhalational anesthesia in the 1840s, the delivery of general anesthesia became routine and permitted the rapid growth of most areas of surgery. However, the techniques favored for delivering inhalational anesthesia until the 1930s remained mask or open drop administration of ether or chloroform, with or without nitrous oxide. Muscle relaxants did not yet exist, and endotracheal intubation was considered an invasive procedure that was used only by a few experts. Typically, patients would breathe spontaneously, and thus could control the depth of anesthesia with their depth and rate of respirations. Also, long before the use of cuffed endotracheal tubes, an intact cough reflex was valued during general anesthesia for protecting the lungs from gastric aspiration, so relatively light planes of anesthesia were the norm. Prior to the introduction of antibiotics in the 1930s, patients frequently presented with empyema, pulmonary abscess or tuberculosis, and often had copious secretions and formidable coughs. Clearly, operating conditions were poor for the early 20th century thoracic surgeon facing a lightly-anesthetized patient asphyxiating and coughing with an unprotected airway. With this in mind, it is no surprise that thoracic surgery remained in its infancy well into the 20th century, until anesthetic techniques progressed sufficiently to provide improved operating conditions.

Prior to the development of antibiotics, the main indication for thoracic surgery was infection. Opening the pleural cavity did not necessarily pose a significant danger to these patients because long-standing infections often resulted in adhesions that formed between the lung and chest wall, preventing the formation of a significant open pneumothorax or mediastinal shift. In fact, repeated aspirations were often attempted to promote the formation of adhesions so that subsequently the pleural cavity could be opened safely, or substances such as air or water were injected into the pleural space as irritants, also to encourage adhesions, in preparation for surgery.^3,4 Another brutal technique to cope with the open pneumothorax, “Muller’s handgrip,” was also woefully inadequate: The surgeon would grab the lung while the chest was open and pull it into the wound to plug the thoracotomy incision.⁵ Pulmonary resection was usually performed using a snare or tourniquet technique, and reoperation would be necessary to remove necrotic tissue. Not surprisingly, such staged procedures could result in sepsis from remaining necrotic tissue. Complications were common and mortality from thoracic surgery was astonishingly high. In a review from 1922 by Howard Lillienthal, the mortality rate for lobectomy performed for chronic pus formation was 42%, and in the 10 cases where more than one lobe was involved, mortality was 70%.⁶

Differential Pressure Breathing

Better anesthetic techniques were sought to meet the demands of thoracic surgeries. The first promising solution to prevent the development of an open pneumothorax was developed in Germany by the surgeon Ernst Ferdinand Sauerbruch.⁷ In 1893, Sauerbruch’s mentor Johann von Mikulicz-Radecki asked him to tackle the “pneumothorax problem,” and his solution, differential pressure breathing, became the prevailing method for anesthetic management in thoracic surgery until World War II. Sauerbruch performed thoracotomies on dogs and found that spontaneous ventilations were sustained without lung collapse if the exposed lung was kept at a pressure 10 cm H₂O below atmospheric pressure, and later used this technique during thoracotomies on humans (Figure 1–1). To provide the negative pressure, the patient and surgical team had to work within a negative pressure chamber constructed of steel, and the patient’s head extended outside the cabinet and was exposed to ambient pressure. Throughout the surgery, the patient would breathe spontaneously and the lungs would remain inflated from the negative pressure within the chamber. The surgeon within the chamber was separated from the anesthetist by a thick wall so that communication was only possible by telephone, and then only with difficulty due to the loud noise in the chamber created by the pump that created the negative pressure. Although impractical, Sauerbruch’s method was considered a triumph and differential pressure breathing was adapted throughout Europe and America; Sauerbruch became a very influential figure in the history of thoracic anesthesia.

Figure 1–1. Sauerbruch’s experimental negative pressure box for performing thoracotomies on dogs. The dog’s chest is enclosed in the box in which the pressure is –10 mm Hg (1904). (From: Mushin WW, Rendell-Baker L, eds. The Principles of Thoracic Anesthesia. Springfield, IL: Charles C Thomas; 1953, with permission. Copyright Wiley-Blackwell.)

Even though Sauerbruch’s methods were highly commended, his negative pressure technique did not gain many followers because it required investment in an expensive and cumbersome negative pressure chamber. However, another option became popular that was based on essentially the same principle. Ludolph Brauer, a colleague of Sauerbruch’s, conducted his own experiments and developed a different solution simultaneously. In fact, his description of the use of a positive pressure chamber was initially presented in the same issue of the same journal as Sauerbruch’s initial presentation of his research. Instead of applying negative pressure to the open chest, Brauer increased the intrapulmonary pressure by placing his subject’s head in a positive pressure chamber. His original apparatus was simply a large box into which the head of the patient was placed after induction of anesthesia. Anesthesia was maintained using oxygen and chloroform, and the patient would breathe spontaneously without assistance. Prior to the opening of the chest, the pressure inside the box would be raised by adding compressed air. Brauer found that if the pressure were raised 10 mm Hg above the atmospheric pressure applied to the open lung, no pneumothorax developed. An obvious limitation and challenge of Brauer’s apparatus was that the anesthetist had no access to the patient’s head during surgery.⁷ Brauer’s device bears a striking resemblance to the helmets used for delivering noninvasive continuous positive airway pressure (CPAP), a tool for treating acute respiratory failure outside of the operating room (OR).⁸

Brauer’s positive pressure technique was the favored method for preventing pneumothorax because the equipment involved was simpler, less bulky, and inexpensive compared with negative pressure chambers. At the same time, even more complicated versions of Sauerbruch’s negative pressure chamber were developed. The American surgeon Willy Meyer modified the Sauerbruch device to create his “universal differential pressure chamber” that included both a positive and negative pressure chamber so that the patient’s head, an anesthetist and assistant could be enclosed in a positive pressure chamber.⁹ He constructed the only negative pressure chamber for such a use in the United States. By using both chambers, the pressure gradient could be maintained by applying positive pressure to the head, negative pressure to the open chest, or both. The chamber was used not only to support respiration during surgery, but also to improve wound drainage and lung expansion postoperatively.¹⁰

Both the positive-pressure and negative-pressure methods relied on maintaining a pressure gradient between the air inside and outside the lungs, otherwise known as differential pressure anesthesia. Both methods were successful at preventing the formerly inevitable open pneumothorax after thoracotomy, but both were ultimately doomed to become historical relics because they provided dangerously inadequate ventilation. Hypoventilation, hypercarbia, hypoxemia, and impaired venous return were significant problems during prolonged cases. Clinical deterioration was not unusual after long cases using these techniques, even though the lungs never collapsed. Meyer recognized that carbon dioxide accumulation was probably the culprit in such cases of unexplained shock, and recommended periodically deflating the lungs by applying rhythmic variations in pressure coinciding with spontaneous respirations to assist ventilation.¹⁰

ENDOTRACHEAL INTUBATION AND ANESTHESIA

While the debate continued regarding the merits of positive versus negative pressure application, an alternative anesthetic method for preventing the development of the open pneumothorax evolved from earlier discoveries in tracheal intubation and mechanical ventilation and became popular in America. This new method, called tracheal insufflation anesthesia, was the clear precursor to the endotracheal anesthesia that is universally used for thoracic surgery today.

Endotracheal Intubation

Tracheal intubation and mechanical ventilation were by no means new discoveries. Because of widespread reluctance to accept tracheal intubation for common use, the course of its development did not follow a smooth path. Andreas Vesalius described tracheal intubation and positive pressure ventilation of a pig in 1543. He performed a tracheotomy and passed a reed into the trachea of a pig and blew into the tube to provide artificial ventilation during a thoracotomy and was able to prevent a potentially lethal pneumothorax. However, his findings went unnoticed and had to be rediscovered. In the 18th century, interest in artificial ventilation for resuscitation grew. In 1788, Charles Kite resuscitated victims of drowning from the Thames using curved metal cannulas that he placed blindly in the trachea. Application of these resuscitation techniques to anesthesia delivery began soon after the discovery of inhalational anesthetics in the 1840s. In 1869, Friedrich Trendelenburg used a tracheostomy tube with an inflatable cuff to administer chloroform during head and neck procedures. William MacEwen, a Scottish surgeon, is credited with the first use of oral tracheal intubation for an anesthetic. On July 5, 1878, MacEwen placed a flexible metal tube in the larynx of an awake patient who was to have an oral tumor removed at the Glasgow Royal Infirmary.¹¹ Unaware of earlier uses of intubation, Joseph O’Dwyer, a pediatrician, performed blind oral tracheal intubations on children suffering from diphtheria in 1885.¹² O’Dwyer later developed a rigid tube with a conical tip that occluded the larynx sufficiently to facilitate positive pressure ventilation. In 1893, George Fell attached O’Dwyer’s metal tube to a bellows and T-piece, creating the Fell-O’Dwyer apparatus. Fell used the apparatus to provide ventilatory support for opioid-induced respiratory depression (Figure 1–2).

Figure 1–2. The Fell-O’Dwyer apparatus (c. 1888). O’Dwyer’s laryngeal tube has a curved right angle and uses fitted, interchangeable, conical heads of different sizes designed to fit securely into the larynx. Rings were provided for the operator’s fingers and the operator’s thumb was placed over the expiratory orifice during inflation. (From: Mushin WW, Rendell-Baker L, eds. The Principles of Thoracic Anesthesia. Springfield, IL: Charles C Thomas; 1953, with permission. Copyright Wiley-Blackwell.)

By the 1890s, there was interest in the application of endotracheal anesthesia to thoracic surgery as a possible solution to the pneumothorax problem. Two French surgeons, Tuffier and Hallion, reported on their use of tracheal intubation and artificial ventilation for thoracotomies on animals in 1896.¹¹ Their device also incorporated a bellows that was used for rhythmic inflation of the lungs, and a water valve that could control the degree of resistance to expiration, a precursor of the modern use of positive end-expiratory pressure (PEEP). Rudolph Matas, among his many pioneering contributions to anesthesiology, made modifications to the Fell-O’Dwyer apparatus so it could be used for surgical purposes. He cited the research of Tuffier and Hallion as his inspiration, and was convinced that these methods were ideal for thoracic cases. His modifications to the Fell-O’Dwyer apparatus included a graduated cylinder for delivery of precise volumes of gases and a mercurial manometer for direct measurement of intrapulmonary pressures. He also added an intralaryngeal cannula connected by a stopcock to a rubber tube and funnel that could be used for administration of chloroform.¹³

Tracheal Insufflation

Until 1907, endotracheal techniques always involved an endotracheal tube that was similar in width to the trachea, through which inspiration and exhalation occurred. However, in 1907, a different method was introduced by Barthélemy and Dufour that became known as “tracheal insufflation”.¹¹ Insufflation anesthesia consisted of placing a thin tube in the trachea and then continuously blowing gases under positive pressure into the lower portion of the trachea. Expired gases escaped between the tracheal tube and the tracheal wall. Meltzer and Auer, American physiologists, used this technique extensively in animal studies. They showed that curarized dogs could be anesthetized by blowing air and ether continuously into a tube inserted into the trachea, and that gas exchange would occur “without any normal or artificial rhythmical respiratory movements whatever” because expired gases could escape around the tracheal tube.¹⁴ Because gas was insufflated continuously, and no rhythmic applications of pressure were used, the insufflation method was similar to Brauer’s positive pressure method; however, efficiency of gas exchange was improved by the decrease in dead space achieved by placing the cannula in the trachea.

Charles Elsberg, a thoracic surgeon in New York City, was inspired by Meltzer and Auer’s physiology research, and he utilized and modified their insufflation technique for application to thoracic surgery. His modifications included replacing the bellows of Meltzer and Auer’s apparatus with an electric motor. He also favored placement of the tracheal cannula under direct vision using either a Killian bronchoscope or Chevalier Jackson’s laryngoscope, after topicalization with cocaine.¹⁵ Elsberg first used insufflation to resuscitate a myasthenic patient who had become cyanotic and pulseless. After initiation of insufflation, her color improved and pulse returned, but resuscitation was discontinued after 5 hours because she did not regain consciousness. Bolstered by his success, Elsberg presided over the first use of tracheal insufflation anesthesia for thoracotomy.¹⁶ In February 1910, a 55-year-old butcher was admitted to the Mt. Sinai Hospital with a 13-month history of productive cough. A diagnosis of lung abscess was made, and the thoracic surgeon Howard Lilienthal sought a definitive operative cure, so he enlisted Elsberg for his expertise with tracheal insufflation. When the pleura was opened, 15 mm Hg pressure was applied, and the lung was described as “two-thirds of its capacity, mottled, and rosy pink in color.” Different pressures were applied and the lung readily collapsed and distended. He recommended the periodic interruption in the stream of insufflation every 2 or 3 minutes to allow the lungs to collapse and improve carbon dioxide elimination, bringing this method closer to modern positive pressure ventilation. The anesthetic was considered a great success, and Elsberg promoted tracheal insufflation for all types of surgery requiring general anesthesia. Just 1 year later, he published on his experiences anesthetizing over 200 patients with this technique.¹⁷ Elsberg’s method of tracheal insufflation strongly resembles the modern practice of oxygen insufflation used during rigid bronchoscopy that was introduced by Sanders in 1968.¹⁸

In the 1920s and 30s, tracheal insufflation anesthesia was the most popular anesthetic method for thoracic surgery in the United States. Insufflation anesthesia became popular in Europe for head and neck surgery because it gave the surgeon better access than mask or hand drop techniques. However, differential pressure anesthesia remained the preferred anesthetic technique for thoracic procedures in Europe for years to come. Reasons for this include the dominance of Sauerbruch and his refusal to endorse any other method. In 1916, Sauerbruch’s own assistant, Giertz, conducted experiments on animals that showed that rhythmic inflation of the lungs was superior to either continuous negative or positive pressure anesthesia. Giertz’s experiments demonstrated that differential pressure anesthesia resulted in inadequate ventilation, carbon dioxide retention, and impaired venous return causing circulatory depression.⁷ Tracheal insufflation was far from perfect. Carbon dioxide accumulation frequently occurred if gas flow went uninterrupted, so modifications to Elsberg’s apparatus were developed that periodically stopped airflow to permit lung collapse. Also, dangerously high-intrapulmonary pressure could occur when the return of gas was impeded. Cases of alveolar rupture and surgical emphysema referred to as “wind-tumor” occurred, probably as a result of vocal cord spasm around thin insufflation catheters interfering with the exit of expired gases.¹¹

Advances in Laryngoscopy

Even though instruments for direct laryngoscopy existed by the 1920s, they were infrequently used. Blind placement of endotracheal tubes required considerable skill and could be a traumatic procedure. Prior to 1895, direct visual examination of the larynx was assumed to be impossible. Alfred Kirstein, a physician in Berlin, is credited with inventing the first direct laryngoscope in 1895.¹⁹ Kirstein’s “autoscope” was not used by anesthetists, but it was the prototype for most laryngoscopes to follow. In 1913, Chevalier Jackson developed his own laryngoscope and published a landmark paper on proper positioning and technique for laryngoscopy.²⁰ In the 1940s, there was a renewed interest in laryngoscope blade design. Robert Miller created the familiar Miller blade in 1941, but the origins of its design are evident in Kirstein’s and Jackson’s laryngoscopes. Only 2 years later, Sir Robert Macintosh released his familiar curved blade that would go on to become the most popular blade in the world.

Endotracheal Tubes

Alongside the development of direct laryngoscopy, came the development of improved endotracheal tubes. World War I produced many casualties with head and neck injuries requiring reconstructive plastic surgery. In 1919, the British anesthetists Ivan Magill and Stanley Rowbotham were assigned to work with the British army plastics unit, and they were forced to adapt endotracheal anesthesia to safely care for these patients. They became experts in blind nasal tracheal intubations to provide unhindered access to the face and airway. They were dissatisfied with the thin endotracheal catheters that were in use for insufflation anesthesia, so they progressed to using wide-bore tubes that more closely resemble what are in use today. By using larger tubes, they returned to the older inhalation method where respiration occurred in both directions through one tube. By doing this, they rejected the popular insufflation technique. Magill’s wide-bore red rubber tubes resisted kinking and were better suited to the contours of the upper airway. “Magill tubes” remained the standard endotracheal tubes until plastic tubes were introduced.

In 1928, Arthur Guedel and Ralph Waters introduced an endotracheal tube with a detachable inflatable cuff (Figure 1–3).²¹ Prior to Guedel and Waters, there were sporadic proponents of cuffed tubes. As early as 1871, Trendelenburg fitted a cuff on a tracheotomy cannula, followed by Eisenmenger in 1893, and Dorrance in 1910.²² However, none of these early attempts to apply cuffs to endotracheal tubes attracted much interest. Guedel demonstrated the effectiveness of the cuff’s seal with his colorful “dunked dog” demonstrations. He submerged his intubated and anesthetized dog, Airway, in an aquarium, from which he emerged unharmed.²³ Guedel’s cuffed endotracheal tube could prevent the aspiration of gastric contents, so it was no longer necessary to keep the patient “light” so the cough reflex would remain intact. Also, since deeper planes of anesthesia could be used, suctioning the trachea without coughing was possible. Aside from aspiration prevention, cuffed endotracheal tubes enabled the most important advancement in anesthetic management for thoracic surgery: the use of controlled positive pressure ventilation. By increasing the depth of anesthesia and delivering controlled breaths using a cuffed endotracheal tube, hyperventilation was now possible to suppress respiratory efforts.

Figure 1–3. Guedel and Waters “new intratracheal catheter” (1928). The catheter is shown deflated and then inflated. The tube was 14 inches long and made of rubber. (From: Mushin WW, Rendell-Baker L, eds. The Principles of Thoracic Anesthesia. Springfield, IL: Charles C Thomas; 1953, with permission. Copyright Wiley-Blackwell.)

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