Nonintubated video-assisted thoracoscopic surgery for the treatment of primary and secondary pneumothorax was first reported in 1997 by Nezu. However, studies on this technique are few. Research in the past 20 years has focused on the perioperative outcomes, including the surgical duration, length of hospital stay, and postoperative morbidity and respiratory complication rates, which appear to be better than those of surgery under intubated general anesthesia. This study provides information pertaining to the physiologic, surgical, and anesthetic aspects and describes the potential benefits of nonintubated thoracoscopic surgery for the management of primary and secondary spontaneous pneumothorax.
Key points
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Nonintubated video-assisted thoracoscopic surgery (VATS) is a feasible and safe alternative for the management of primary or secondary spontaneous pneumothorax.
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A variety of anesthetic techniques have been reported, and methods for managing the airway, analgesia, and sedation should be separately considered.
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Surgical techniques for nonintubated VATS bullectomy and pleurodesis are similar to those for the intubated approach.
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Hypercapnia may become intolerant in risky patients, and noninvasive ventilator should be prepared.
Introduction
Definition
The term pneumothorax was first presented in 1803. At that time, most cases of pneumothorax were secondary to tuberculosis, although some involved otherwise healthy patients (“pneumothorax simple”). The term “primary spontaneous pneumothorax” (PSP) was first used in 1932 to describe pneumothorax in healthy young individuals with no underlying respiratory disease. Currently, pneumothorax is classified by the cause or according to the underlying respiratory disease. PSP is defined as pneumothorax without traumatic injury or related pulmonary disease, whereas secondary spontaneous pneumothorax (SSP) refers to pneumothorax that develops in the presence of an underlying pulmonary condition, such as chronic obstructive pulmonary disease (COPD), cystic fibrosis, or Pneumocystis carinii pneumonia. Because of the effect of the preexisting lung disease, the management of SSP is potentially more difficult.
Treatment Choice and Indications
Currently, the optimal treatment of PSP and SSP is debatable. Generally, observation, simple aspiration, and chest tube insertion are used in the initial treatment course, whereas surgery and pleurodesis are suggested for recurrent or complicated pneumothorax. Surgical intervention involving video-assisted thoracic surgery (VATS) for bullectomy and pleurodesis ( Fig. 1 ) has shown satisfactory results, with most procedures performed under general anesthesia with lung isolation using a double-lumen endotracheal tube.
Double-lumen endobronchial tubes have been used since the development of modern thoracic surgery in 1959. These tubes facilitate single-lung ventilation, are safe, and allow easy manipulation of the lungs. However, several unavoidable disadvantages have been recorded over decades of observation; these include postoperative pneumonia, impaired cardiopulmonary function, ventilator-related barotrauma, lung atelectasis in both dependent and nondependent individuals, neuromuscular side effects, and major airway injury. Fortunately, rapid improvements in minimally invasive surgeries, primarily VATS, have resulted in the development and evolution of nonintubation anesthesia, with several studies proving its safety and feasibility in cases involving various thoracic conditions, such as solitary lung tumors (resection), interstitial disease, empyema thoracis (pleural decortication), mediastinal tumors (excision), bullous disease associated with pneumothorax, and emphysematous pulmonary disease. The aim of the present review is to discuss the feasibility and outcomes of nonintubated thoracoscopic surgery for pneumothorax.
Factors involved in nonintubated video-assisted thoracoscopic surgery
Respiratory Physiology: Oxygenation and Ventilation
For the maintenance of an effortless respiratory pattern during surgery, there should be no obvious mismatch between the alveolar ventilation (V) and alveolar blood flow/perfusion (Q), particularly in patients with compromised cardiopulmonary function. Conditions with a mismatch between ventilation and perfusion (V/Q mismatch), such as heart failure, pulmonary embolism, lung collapse, and sputum accumulation, which exhibit a high incidence in older patients with chronic cardiopulmonary diseases (COPD, interstitial lung disease [ILD], cystic fibrosis), can compromise the efficiency of oxygenation.
Locoregional Anesthesia
Generally, the area of regional anesthesia includes the chest cage and parietal pleura. Commonly used techniques include thoracic epidural anesthesia/analgesia (TEA), paravertebral nerve block, percutaneous or thoracoscopic intercostal nerve block (ICNB), and intrapleural analgesia. However, each technique has certain indications and contraindications, particularly for high-risk patients.
TEA can also induce motor blockade in the respiratory muscles within the thoracic cage, with a 10% decline in the lung volume (vital capacity, functional residual capacity [FRC], forced vital capacity [FVC], and forced expiratory volume in 1 second [FEV1]). Moreover, it is a time-consuming and technically demanding procedure and can cause peripheral vasodilation and functional hypovolemia owing to sympathetic blockade. Neurologic and cardiorespiratory complications have also been occasionally reported. Consequently, ICNB is sometimes used as an alternative. Vagus nerve block and intravenous narcotics are also reliable tools for minimizing visceral pain. These methods preserve the phrenic nerve (origin in the neck [C3 to C5]), consequently maintaining the function of the diaphragm.
Anesthetic Management
With regard to the sedation level during nonintubated VATS, patients are generally fully awake or moderately to deeply sedated. Diverse depths of sedation are particularly necessary for anxious patients or patients requiring prolonged surgery. Inhaled anesthetics administered through laryngeal airway masks and intravenous anesthetics (eg, propofol, midazolam) ( Fig. 2 ) have shown satisfactory results in such cases, although these anesthetic agents inadvertently reduce FRC.
Spontaneous Breathing
Preservation of FRC of the dependent lung is one of the benefits of nonintubated surgery. In intubated patients, the overall FRC reduces once the induction of anesthesia is initiated. As a result, the nondependent lung becomes more compliant, whereas the dependent lung shifts to a less compliant area in the pulmonary compliance curve. Administration of a muscle relaxant for ventilation control results in redirection of the tidal volume. Without spontaneous diaphragmatic contraction, the abdominal pressure results in increased tension and, consequently, an obvious reduction in FRC.
Permissive Hypercapnia
Without lung separation, communication between the dependent and nondependent lungs during surgical pneumothorax would lead to “carbon dioxide rebreathing,” which results in hypercapnia. Because the hypercapnia can trigger tachypnea, respiratory depressants, such as opioids or sedatives, are administered in these cases. In the past, respiratory depressants were associated with concerns about deterioration in ventilation and oxygenation. However, more recent studies have shown that the degree of hypoventilation induced by these agents is not clinically significant. A face mask, a laryngeal mask airway, a high-flow nasal cannula, or an oropharyngeal cannula can be used for supplemental oxygen delivery. A perioperative increase in the carbon dioxide level is not considered harmful if it is within the range used for permissive hypercapnia.
Surgical Pneumothorax
Surgical pneumothorax is created after opening the nondependent hemithorax. The dependent lung would bear the full weight of the mediastinum because of the lack of a negative intrapleural pressure in the nondependent hemithorax. At this time, reductions in FRC and the ventilation volume become apparent. Moreover, there is a decrease in the caval venous return, which results in a decrease in the cardiac output and pulmonary perfusion. The increasing vascular resistance in the collapsed nondependent lung may shift the pulmonary blood to the dependent lung and improve the V/Q ratio. Nevertheless, the decline in the cardiac output may worsen the blood oxygen-carrying capacity, influence the mixed oxygen saturation, and deteriorate oxygenation. The use of a sedative drug or TEA can significantly influence this compensation. The medication should be carefully titrated, particularly for patients with impaired cardiopulmonary function.
Rationale and potential advantages of nonintubated video-assisted thoracoscopic surgery for spontaneous pneumothorax
Primary Spontaneous Pneumothorax
Patients with PSP are mostly young adults without contraindications for nonintubated VATS. In the field of minimally invasive thoracic surgery, nonintubated VATS is potentially a less invasive procedure for the management of PSP and is associated with better procedure acceptance, faster postoperative recovery, and a shorter hospital stay. Furthermore, surgery-related costs may decrease because of the low incidence of adverse effects.
Secondary Spontaneous pneumothorax
Patients with SSP are generally elderly with an underlying pleural or pulmonary disease, namely COPD, ILD, or cystic fibrosis or other less common diseases. Regardless of the cause, the morbidities and mortalities for SSP are higher than those for PSP. In most patients with SSP, the performance status and cardiopulmonary function are generally poor, with a high likelihood of a reduced FEV1 and FEV1/FVC ratio.
General anesthesia in SSP patients can result in hemodynamic instability, alveolar barotrauma, volutrauma, and atelectrauma in the perioperative period, and some patients cannot undergo surgery because of the impaired pulmonary function and high incidence of cardiopulmonary complications caused by general anesthesia. Therefore, conservative treatment has often been the first line of treatment in the past. However, of late, the role of surgical treatment, particularly VATS, has become indisputable. Although most VATS procedures for SSP are performed under general anesthesia, nonintubated VATS precludes the need for general anesthesia and prevents ventilator-induced damage. Previous reports recommend that patients with SSP who are contraindicated for surgery because of the risk of cardiopulmonary complications should undergo awake surgery performed by experienced surgeons. Studies by Noda and colleagues and Mineo and Ambrogi also showed the clinical benefits of awake thoracoscopic surgery in patients with SSP, including a lower incidence of postoperative respiratory complications and reduced expression of stress hormones and systemic inflammatory markers. Avoidance of neuromuscular blockade, which prevents atelectasis in the nonoperated dependent lung and lowers the risk of hypoxia and ventilator dependency, is another important consideration in nonintubated surgery. It maintains FRC and preserves the compliance of the dependent lung, thus maintaining adequate perfusion and preventing a V/Q mismatch. All of these effects are vital for patients with SSP. The risk of hypoxemia and hypercapnia is also lower with nonintubated anesthesia than with intubated general anesthesia.
Previous research has documented the mechanism of hypoxic pulmonary vasoconstriction. The vessels in nonventilated areas are redirected to the ventilated areas. The volatile anesthetics used for general anesthesia suppress the compensation mechanism, whereas intravenous anesthetics, such as propofol, and TEA agents, such as bupivacaine, ropivacaine, and xylocaine, have a negligible influence on the mechanism of hypoxic pulmonary vasoconstriction. Nonintubated surgery may be a safer choice for patients with long-term hypoxic conditions, such as pulmonary fibrosis and emphysema. Some metaanalyses showed that nonintubated surgery reduced cardiac morbidity and mortality after noncardiac procedures, whereas other studies showed that nonintubated surgery could prevent a third of the pulmonary infections and half of the pulmonary complications induced by general anesthesia. Nonintubated surgery is also associated with earlier mobilization and improved coughing ability because of lesser opioid use, which prevents the accumulation of secretions and prevents respiratory infection. These benefits lower the overall risk for patients with SSP.
Anesthetic considerations
Anesthetic Choice
In 1997, Nezu and colleagues reported the potential of local anesthesia (LA) with sedation during thoracic surgery for spontaneous pneumothorax. Subsequently, clinicians began using TEA, which became the most common analgesic technique ( Table 1 ). TEA has been applied in almost every study concerning nonintubated thoracoscopic surgery for PSP and SSP. However, it is technically demanding and causes potential side effects; therefore, ICNB is used as an alternative technique for regional anesthesia. Guo and colleagues reported a retrospective cohort study involving 240 cases subjected to VATS bullectomy under total intravenous anesthesia (TIVA)/TEA or TIVA/LA. The short-term outcomes and recurrence rates showed no significant differences between the 2 anesthetic techniques, and the investigators suggested that TIVA/LA may be a suitable alternative to TIVA/TEA for the surgical management of PSP.
| First Author, y | Study Design | Patient Number | Anesthesia | Ports | Pleurodesis | Morbidity (%) | Recurrence Rate (%) | Hospital Stay |
|---|---|---|---|---|---|---|---|---|
| Nezu a et al, 1997 | Observational study | 32 | ICNB + TIVA | 3 | Fibrin glue | 9.4 | 3.1 | 4.5 ± 1.3 |
| Pompeo et al, 2007 | Randomized controlled trial | 43 | TEA/GA | 3 | Abrasion | 4.5 | 4.5 | 2.0 ± 1.0 |
| Rocco et al, 2011 | Case report | 1 | TEA + TIVA | 1 | Abrasion with talc pleurodesis | — | No | 1 b , c |
| Onodera et al, 2013 | Case report | 1 | TEA + TIVA | 1 a | — | — | No | 2 b |
| Chen et al, 2013 | Case report | 1 | TEA + TIVA + Vagal block | — | Abrasion | — | No | 4 b |
| Li et al, 2015 | Observational study | 32 | TEA + TIVA | 1 | — | — | 0 | 1.7 ± 0.3 |
| Guo et al, 2016 | Observational study | 240 | TIVA-TEA/TIVA-ICNB | 2 | — | 2/2 | 3/2 | 3.4 ± 1.5/2.7 ± 1.5 b |
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