Pneumothorax: A Concise Review and Surgical Perspective

Abstract

Pneumothorax is the collection of air in pleural cavity, which is commonly due to development of a communication between pleural space and alveolar space (or bronchus) or the atmosphere. In this chapter, we will discuss the various aetiologies of pneumothorax, the differences in their pathophysiology and the implications on the management of the disease. The chapter focusses on the surgical aspects in the management, the revolution brought in by video-assisted thoracoscopic surgery (VATS) and the advancement of the field by introduction of uniportal VATS and robotic-assisted thoracic surgery. The principles of management of catamenial pneumothorax are revisited. The chapter also throws light on the nuances of anaesthesia techniques and the latest developments are outlined. Lastly, a section is dedicated to COVID-19 associated pneumothorax and the approach to its management.

1. Introduction

The term “pneumothorax” was coined by a French physician Itard, in 1803 [1]. Pneumothorax is defined as the presence of air in the pleural space. Even though intrapleural pressures are negative throughout the respiratory cycle, air does not enter the pleural space, as the net movement of gases from capillary blood into pleural space requires pleural pressures to be lower than −54 mmHg, which does not occur in normal circumstances. Hence, for air to be present in pleural space, one of the three events must occur: communication between pleural space and alveolar space (or bronchus), or communication between pleural space and the atmosphere, or presence of gas-producing organism in the pleural space [2].

Clinically, pneumothorax is classified as spontaneous (no obvious precipitating factor present) and non spontaneous (consequence of any thoracic injury). Spontaneous pneumothorax may be primary (no apparent underlying lung disease) or secondary (associated with clinically apparent underlying disease, like chronic obstructive pulmonary disease, cystic fibrosis), or catamenial (associated with menstruation). Pneumothorax can be of varying clinical severity, ranging from a small pneumothorax, which is likely to resolve spontaneously, to those with large pleural defects and collapse of entire lung and compromised ventilation.

Pneumothorax ranks second to rib fracture, as the most common manifestation of traumatic chest injury and is noted in 40–50% of patients with chest trauma [3]. Weissberg et al. in a study of 1199 cases of pneumothoraces found secondary spontaneous pneumothorax (505 patients) to be most common, followed by primary spontaneous pneumothorax (218 patients), traumatic pneumothorax (403 patients), and iatrogenic pneumothorax (73 patients) [4].

2. Pathophysiology

Normally, the pressure in pleural space is negative compared to the alveolar pressure during the entire respiratory cycle, due to the inherent elastic recoil of the lung. The pleural pressure is also negative with respect to atmospheric pressure. Development of communication between alveolus or atmosphere and the pleural space allows air to flow into the pleural space until there is no longer a pressure difference or until the communication is sealed [5].

Tension pneumothorax is a condition where there is continuous increase in the air trapped in the pleural space, due to formation of a one-way valve by the injured tissues. This trapped air builds up pressure on the affected side, causing collapse of the ipsilateral lung and shift of mediastinum into the contralateral hemithorax. This causes respiratory distress. Also, there is reduced venous return and thus decreased cardiac output. Further, hypoxia leads to increased pulmonary vascular resistance via vasoconstriction. Cardiopulmonary arrest becomes imminent. Tension pneumothorax, thus, culminates in a life-threatening condition.

Spontaneous rupture of blebs may result in pneumothorax. The rupture may be a consequence of pressure change, as seen in airplane crew members or scuba divers [6]. The volume of given mass of gas at a constant temperature is inversely proportional to its pressure. A given volume of air at an altitude of 3050 m, saturated at body temperature, expands to 1.5 times the volume at sea level. Scuba divers breathe the compressed air delivered by a regulator and during ascent, as ambient pressure falls rapidly, gas in the lungs expands and may rupture blebs [7].

Secondary spontaneous pneumothorax may be due to rupture of pre-existing blebs or due to areas of increased porosity. These are areas of disrupted mesothelial cells on the visceral pleura, replaced by an inflammatory elastofibrotic layer with increased porosity, allowing air leak into the pleural space [8]. Pneumothorax has, also, been reported to be the presenting sign of peripheral necrotic tumour or centrally located tumour.

Catamenial pneumothorax is defined as two episodes of pneumothorax temporally related to the onset of menses, usually within 72 hours. Catamenial pneumothorax is the presentation of thoracic endometriosis and thorax is the most common site of extra pelvic endometriosis. An older age at diagnosis (34.2 ± 6.9 years), and right sided lesions predominate the clinical picture. Thirty-nine percent of patients have associated diaphragmatic lesions. Diverse hypothesis have been advanced to explain the pathogenesis of endometriosis related pneumothorax: spontaneous rupture of blebs, shedding of endometrial implants of visceral pleura, and the transdiaphragmatic crossing of air from the genital tract during menses. Known risk factors associated with thoracic endometriosis include previous gynaecologic surgery (such as curettage for miscarriage, hysteroscopy for endometrial biopsy, or revision of the uterine cavity after caesarean section), primary or secondary infertility, and the history of pelvic endometriosis.

Iatrogenic pneumothorax may be caused during transthoracic needle aspiration or biopsy, subclavian or jugular vein catheterization, thoracocentesis, mechanical ventilation, cardiopulmonary resuscitation, tracheobronchial biopsy, among the commonly reported causes. Rarer reported causes are liposuction of axilla fat, liver biopsy, colonoscopy and gastroscopy [9]. Surgeries with operative fields far removed from thorax, have been reported to be associated with pneumothorax, such as orthognathic surgery [10]. Iatrogenic pneumothorax related to mechanical ventilation has been reported in up to 15% of ventilated patients [11].

Communication between a bronchus (main stem, lobar or sublobar bronchus) and pleural space, called bronchopleural fistula, usually results as a complication of lung-resection surgery. The incidence of bronchopleural fistula is up to 1% after lobectomy and about 4–20% after pneumonectomy [12].

3. Diagnosis

3.1 Clinical examination

On inspection, tachypnea, increased work of breathing and respiratory distress may be seen. Cyanosis, drowsiness and decreased oxygen saturation may be found in tension pneumothorax. On palpation, tachycardia, chest wall tenderness, subcutaneous emphysema, decreased chest wall expansion, decreased tactile fremitus and tracheal shift are noted.

Hyper-resonant notes on percussion over the affected lung fields and decreased air entry perceived on auscultation are indicative of pneumothorax. There may be absent breath sounds on the ipsilateral side with contralateral reduced air entry in tension pneumothorax. Iatrogenic pneumothorax should be suspected in any patient who becomes more dyspneic after a medical or a surgical procedure that is known to be associated with the development of the pneumothorax. Sudden increase in peak airway pressure and sudden decline in oxygen saturation in a patient on mechanical ventilation should ring warning bells for the intensivist.

3.2 Investigation

A chest X-ray may reveal free air around the periphery of the lung fields and decreased lung volume. It may demonstrate the aetiology of the pneumothorax, such as rib or sternal fractures or presence of emphysematous lungs. Films should be taken in erect position, because in supine position, air spreads out in whole of pleural cavity, and films may appear normal, even in the presence of significant air. In patients who cannot be positioned erect and need to be supine, a deep sulcus sign (deep lateral costophrenic angle) should be looked for [13].

Methods to determine the size of pneumothorax on chest X-ray give approximate idea only. There are currently two methods described in adults. If the lateral edge of the lung is >2 cm from the thoracic cage, then, it implies air is occupying at least 50% of thoracic volume and hence, pneumothorax is large in size. Another method is measuring the fractional change in linear dimension of lung, and that multiplied by a factor of three, gives the fractional volume of pneumothorax [14].

Computed tomography (CT) chest provides more accurate information regarding volume of pneumothorax and associated pathology. Obtaining X-ray or CT images may be problematic and time-consuming in poly-trauma patients. Nowadays, in many trauma centres, pneumothorax is detected by sonography and has been included as a part of focused abdominal sonography for trauma (FAST) examination [15]. Ultrasound plays a important role in patients who are not stable enough for chest X-ray and CT. Also, ultrasound is not invasive and the patient is not exposed to radiation. According to a study of Blaivas et al., chest X-ray and ultrasound have a sensitivity of 75.5 and 98.1%, respectively and a specificity of 100 and 99.2%, respectively [16].

Bronchopleural fistula should be suspected in a lung resection patient with large continuous air leak and signs of empyema (leukocytosis, fever, purulent fluid on thoracocentesis, and pleural fluid on chest X-ray or CT scan). Large pneumothorax developing days or weeks after resection is strongly indicative of a bronchopleural fistula. There is often a persistent and worsening cough. Since these patients have high mortality rates, of 11–18% for early fistula (within 30 days of surgery) and 0–7% for late fistula (beyond 30 days of surgery), they should be evaluated thoroughly by CT scan and flexible bronchoscopy. Bronchopleural fistula is separately discussed thoroughly elsewhere.

4. Management

4.1 Initial management

Initial management of pneumothorax patients involves ensuring adequate airway, providing supplemental oxygen, securing an intravenous line, looking for signs of compromised breathing and deciding on the need of tube thoracostomy. Tension pneumothorax should be diagnosed by clinical assessment and a tube thoracostomy/needle thoracocentesis should be performed immediately. Scant data exists in literature proving the efficacy of needle thoracocentesis procedure. However, when tube thoracostomy is anticipated to take time, a needle thoracocentesis may be done immediately, to save life.

Tube thoracostomy is an emergency procedure and is mandatory where pneumothorax is large, or patient has respiratory compromise. Some centres practice drainage of all traumatic pneumothoraces irrespective of symptoms [11]. This line of management in simple pneumothorax is considered invasive by other centres, who recommend observation and oxygen supplementation for small pneumothoraces.

Sucking chest wounds require immediate sealed-cover with an occlusive, air-tight, clean plastic sheet. The sterile inside of gloves-packet can be used in an emergency situation. No patient with penetrating chest wound should be neglected, as tension pneumothorax or life-threatening respiratory emergency can arise.

Upright positioning is beneficial unless contraindicated, like in spinal injury. In a patient with pneumothorax who requires air transport, it is essential that an intercostal tube with Heimlich valve be placed prior to transfer, as pressure changes during flight will cause progression in the severity of the injury and may potentially lead to development of tension pneumothorax.

Pain impairs the ability of the person to breathe, further compromising lung mechanics, in inflammed and contused lungs. In addition, it causes the retention of pulmonary secretions which further suppresses the patient’s cough reflex, finally leading to atelectasis and increasing morbidity, Nonsteroidal anti-inflammatory drugs, systemic opioids or regional analgesia methods such as epidural analgesia, intrapleural analgesia, intercostal nerve block, and thoracic paravertebral block have been used for pain control.

Supplemental oxygen therapy, instead of room air, accelerates the resorption of air in pleural cavity by four-fold. By breathing 100% oxygen instead of air, alveolar pressure of nitrogen falls, and nitrogen is gradually washed out of tissue and oxygen is taken up by vascular system. This builds substantial gradient of nitrogen between tissue capillary and the pneumothorax space, resulting in multifold increase in absorption from pleural space. About 1.25% of the volume of pleural air is absorbed in 1 day; hence 25% of the volume is absorbed in 20 days [17]. Small pneumothoraces are often managed with oxygen administration and monitoring via chest X-rays.

4.2 Tube thoracostomy

Correct placement of the tube is seen as the stream of the bubbles during expiration and coughing and the rise on the level of fluid in the underwater seal during inspiration. Complications of tube thoracostomy include injury to lung or mediastinum, haemorrhage (usually from intercostal artery injury), neurovascular bundle injury, infection, bronchopleural fistula, and subcutaneous or intraperitoneal tube placement.

Heimlich valve or the Vycon self-sucking chest drainage valve are applied directly to the chest tube and reduce or eliminate the underwater drainage period. The Heimlich flutter valve is quite inconspicuous under clothes and makes ambulatory treatment possible. The valve is made of latex rubber that acts as one-way valve, letting air out and preventing reentry. The Vycon device is a double self-sucking valve. It has a soft plastic casing that allows application of manual pressure to aspirate air or fluid [18].

If the lung remains unexpanded or if there is a persistent air leak 72 hours after tube thoracostomy, thoracoscopy or thoracotomy should be considered. Presence of hemopneumothorax, bilateral pneumothorax, first contralateral pneumothorax and pregnancy may be considered for early invasive treatment [19].

Tube thoracostomy is usually sufficient to treat primary spontaneous pneumothorax. However, Schramel et al. reviewed 11 studies over 32 years, involving 1242 patients with primary spontaneous pneumothorax, treated with needle aspiration or tube drainage, and concluded that about 30% patients have recurrence of pneumothorax [20]. Risk factors for recurrence are radiographic evidence of pulmonary fibrosis, smoking, asthenic habitus and younger age [21]. Presence of blebs or bullae was not found to be significantly associated with recurrence [21]. Of patients with recurrent pneumothorax after initial spontaneous pneumothorax, 72% will develop a subsequent pneumothorax within a 2-year period [21]. Recurrent spontaneous pneumothorax or persistent air leaks at initial presentation are indications for operative treatment. Patients in occupations with excessive pressure changes (pilots and divers) or those residing in remote areas, are candidates for operative intervention after a single episode of spontaneous pneumothorax to prevent a potentially life-threatening recurrence.

Clinical picture in secondary spontaneous pneumothorax (SSP) is complicated by the presence of underlying diffuse lung disease, such as chronic obstructive pulmonary disease (COPD), cystic fibrosis, tuberculosis, fibrotic lung diseases such as idiopathic pulmonary fibrosis, and autoimmune diseases involving pleura such as rheumatoid arthritis, ankylosing spondylitis, systemic sclerosis, and Sjogren’s syndrome. Observation without evacuation of the pneumothorax, is usually not possible because these patients usually are very symptomatic. Simple aspiration is less likely to be successful in SSP than in primary pneumothorax [22]. It is attempted as an initial treatment in small (air space <2 cm) pneumothoraces in minimally breathless patients under the age of 50 years. If the patient with SSP is 50 years or older, and if the rim of intrathoracic air is larger than 2 cm on a chest X-ray, intercostal tube drainage is advocated. Clinically unstable patients should have a chest tube inserted, notwithstanding the size of the pneumothorax. Sixty-one to seventy percent of leaks resolve by day seven of tube drainage. Further drainage is unlikely to improve success. If air leak does not stop after 48 hours of continuous drainage, consultation for surgical intervention is recommended because of significantly lower healing rate of pleura in cases of SSP compared with primary spontaneous pneumothorax [23].

Indications for operative treatment include persistent air leak, recurrent pneumothorax, pneumothorax after pneumonectomy or intolerance of the prolonged effects of pneumothorax, not relieved by more conservative approaches.

4.3 Surgical method

Prevention of persistent air leak or future recurrence requires initial identification of the source of the air leak, that is, macroscopic blebs or bullae. Bullae are air filled spaces within the lung parenchyma resulting from the progressive destruction of alveolar tissue. Typically they have relatively thick fibrous walls, grow progressively larger, and are poorly ventilated and with poor perfusion. A giant bulla is defined as one which occupies more than one third of the chest cavity. Complete intrathoracic inspection requires division of all pleural adhesions since these often conceal the culprit lesion. The source of air leak is then controlled by stapling, or suturing.

After completion of the bleb resection, pleurodesis is performed to decrease risk of recurrence. Horio et al. has shown, in a comparative study, that recurrence rate diminished from 16 to 1.9%, when pleurodesis is added to bullectomy [24]. Areas of pleural porosity are potential sources of recurrence, and may be too widespread to be resected. Hence, pleural symphysis is important.

There are three basic approaches to achieve the principles above: thoracostomy, thoracoscopy or thoracotomy. Video-assisted thoracoscopic surgery (VATS) is enabled by the insertion of a 5- to 10-mm videothoracoscope via a 1- to 2-cm incision in the lateral sixth intercostal space. Two more similar incisions are placed anteriorly and inferiorly in the fourth and seventh intercostal space (Figure 1). Instruments are introduced via rigid or flexible ports. Adhesions are taken down with sharp dissection. Bleb excision or bullectomy is carried out with an endoscopic linear cutter. The bullae are deliberately opened by cautery or scissors and allowed to deflate. An endoscopic lung clamp is used to grasp the bulla and is then rotated repeatedly as if winding a clock. This action collapses the bulla onto itself and the demarcation between bulla and normal lung parenchyma is revealed. Small ventilated breaths to the ipsilateral lung can also highlight this transition zone. The endoscopic linear cutter stapler is then used to amputate the base of the bulla (Figure 2). Alternatively, bleb may be ligated using a pre-tied Roeder slip knot, introduced by an external applicator.

Figure 1.

Port placement for blebectomy [25].

Figure 2.

Apical bullectomy using ring forceps and endoscopic stapler [25].

When excising the emphysematous bulla, the staple lines must be reinforced to reduce chance of postoperative air leak. Application of buttress material in the staple line distributes tension throughout the staple line, seals off the staple holes and narrows the spaces between each staple, thus reducing tearing at the staple line. Additionally, the buttress provides a broader pressure profile around each individual staple across the staple line, leading to potentially improved haemostasis. Material such as fibrin glue, bovine pericardium, poly-glycolic acid, polydioxane ribbon, Teflon felt, collagen patches and polytetrafluoroethylene (PTFE) sheets have been used to reinforce staple line. Nonabsorbable synthetic materials carry the potential hazard of inflammation and/or bacterial colonisation. Biomaterials originating from animal tissues have a risk of cross-species transmission of infection.

Accessory ports are removed under direct thoracoscopic guidance and the sites inspected for haemostasis. A 24 or 28 F drain is placed to the apex of the hemithorax. This is brought out of one of the port sites and connected to underwater seal drainage and suction. The lung is inflated under direct vision by the scope to verify complete inflation, locate additional blebs, and insure proper placement of the chest tube to the apex of the hemithorax. An inflated lung can displace a tube 2–3 cm caudally. If not corrected, this will frequently lead to a loculated pneumothorax at the apex and thwart the pleurodesis. The sites are closed in two layers with an absorbable suture.

Open surgery is usually performed via muscle-sparing thoracotomy. A lateral or axillary thoracotomy via the fourth intercostal space preserving the fibres of latissimus dorsi and with minimal rib retraction is the approach of choice. Bullae are opened, bronchial edges are oversewed, edges of the bullae are unfolded and stapled. Exogenous materials are buttressed to minimise postoperative air leak.

Randomised prospective study comparing VATS with axillary thoracotomy found no significant difference in postoperative blood loss, lung function, postoperative pain, use of analgesics, postoperative complications, duration of hospital stay and resumption of normal activities. However, with a minimum follow-up of 2 years the recurrence rate after VATS was 4.3% and after a limited thoracotomy, was 0% [26].

However, for recurrent pneumothorax, a randomised study found significantly longer operative time with VATS. Complication rate, chest tube duration, hospital stay, and incidence of chronic pain were not significantly different [27].

In multiple studies, VATS was found to be associated with higher recurrence rate compared to open thoracotomy [28, 29, 30]. Barker and colleagues performed a meta-analysis by comparing the reported recurrence rates in patients undergoing VATS with those having open surgery. Results showed a four-fold increase when a similar pleurodesis procedure is performed with a video-assisted approach compared with an open approach [28]. One of the reasons attributed to it was insufficient visualisation of bullae or blebs on the lung by thoracoscopy. Another reason quoted was less adhesion between the lungs and the chest wall postoperatively when VATS is performed compared with open thoracotomy. Inspite of this, many thoracic surgeons prefer the VATS approach as it is less invasive, less painful, and associated with a shorter hospital stay [31]. VATS is, thus, now considered approach of choice for elderly patients or those with multiple comorbidities [32, 33].

Migliore et al. approached pneumothorax through single port, using handcrafted 20 mm flexible trocar [31]. Jutley et al. compared the standard three-port VATS and uniVATS for surgical management of spontaneous pneumothorax and demonstrated safety and effectiveness with the latter technique [34]. Reduction of intraoperative blood loss and postoperative pain with a higher patient’s satisfaction score in uniVATS emerged from a propensity matched comparative analysis by Dai et al. [35]. However, retrospective comparison of uniport versus multiport VATS lobectomies by Chang et al. revealed no difference in operative time, postoperative 30-day mortality, chest tube permanence, hospital stay and reoperation rates [36].

More recent advance in the field of thoracic surgery is robotic-assisted surgery. The surgeon sits at a console, away from the patient in operating room and controls the instruments, including camera, on the robotic surgical system. A small 3D high-definition camera is placed through one of the incisions to provide a good view of the chest cavity, while wristed robotic instruments are inserted through the other small incisions.

For bilateral bullous disease, staging the operations is preferred, to minimise morbidity as well as to allow the ipsilateral lung to re-expand completely, optimising the patient’s functional status before tackling the contralateral lesion.

Catamenial pneumothorax with mild symptoms is usually managed with simple rest and thoracocentesis or chest tube for symptomatic relief. The surgical aspects include removal of blebs and bullae, wedge resection, and pleurodesis (abrasion or talc). Most surgical treatment is performed by thoracoscopy, and pleurodesis has been advocated to reduce recurrences. Endometrial deposits on diaphragm are removed as conservatively as possible to spare the diaphragmatic function. Multiple small defects are repaired by titanium clips. The diaphragm is finally reinforced by Prolene or Gore-Tex® mesh. Spiral clips are placed radially at the border of the prosthesis [37]. There is still no agreement regarding whether a prosthetic repair should be recommended. Bagan et al. reported fewer recurrences after diaphragm reinforcement with polyglactin mesh [38]. Concern exists about the use of VATS for large diaphragm defects. Minimally invasive approach is not fully supported by evidence. Both sides of the diaphragm need to be evaluated if one side is noted to have endometrial implants. Superficial diaphragmatic endometriosis can be treated with cold scissors, monopolar energy, bipolar energy, CO₂ laser, or a plasma energy source [39]. Bagan et al. suggested application of surgical treatment during menses, for better visualisation of the endometriotic lesions [38].

Postoperative treatment with GnRH agonists or oral contraceptives for 6–12 months is suggested for all patients with proven catamenial pneumothorax for symptomatic relief and to reduce recurrences. The goal of early GnRH analogues administration is to prevent cyclic hormonal changes and induce suppression of ectopic endometrium activity, until accomplishment of effective pleurodesis, since formation of effective pleural adhesions require time [40]. Longer period of hormonal treatment (median 17.5 months) has been required after reoperations for catamenial pneumothorax. Recurrence rate varied from 14.3 to 55%.

4.4 Pleurodesis (mechanical and chemical) and parietal pleurectomy

Pleural symphysis is used to obliterate the potential space between pleural surfaces to prevent recurrent pneumothorax. This is accomplished by inducing an inflammatory reaction between the visceral and parietal surfaces with a chemical agent, mechanical abrasion or by stripping the parietal pleura which results in fusion of the visceral surface to the denuded thoracic wall. Chemical agents include talc, doxycycline, tetracycline, bleomycin, iodopovidone, Corynebacterium parvum and silver nitrate. Mechanical pleurodesis is done by vigorously abrading the parietal pleural surface with tightly rolled gauze, held by ringed forceps or a Bovie scratch pad (Figure 3).

Figure 3.

Method of mechanical pleurodesis [25].

Parietal pleurectomy involves sacrifice of the parietal pleura. With the help of saline infusion in sub-pleural space, the parietal pleura can be bluntly dissected with a end-forceps. Alternatively, electrocautery can be used. Ayed and Chandrasekran suggested that in apical region, pleurectomy might be a more effective procedure than pleural abrasion [41].

In a randomised prospective study of 96 patients, pleurodesis by talc slurry resulted in the lowest recurrence rate of 8%, compared to 13% with tetracycline and 36% with simple tube drainage [42]. Talc is insufflated into the chest so that complete dispersion throughout the hemithorax is accomplished. This is typically accomplished with an atomizer. Alternatively, talc can be blown into the chest from a LUKI tube in front of a 6 L/minute oxygen flow rate. Alternatively, talc slurry can be instilled through a chest tube in patients who are not surgical candidates.

Talc is cheap. Talc instillation carries a low risk. However, complications such as pulmonary edema, acute respiratory distress syndrome, and hypotension have been reported [43, 44]. In an experimental study in rats, rapid absorption of talc from the pleural space was seen and systemic distribution might explain the complications [45]. Thus, size of the talc particles seems important, smaller particles inducing more systemic complications. In a recent prospective European multicentre study, thoracoscopic pleurodesis with 2 g of graded talc consisting of large particles, was found to be safe after a 30 day observation period [46].

Talc induces a painful inflammatory reaction on the pleural surfaces, which requires adequate analgesia. Aggressive pleurodesis methods should be avoided in chronic obstructive pulmonary disease patients who are suitable for lung transplantation, to reduce graft implantation complications.

In a comparative, randomised study including 73 patients with pleural effusion or spontaneous pneumothorax, talc and iodopovidone were found to be equally efficient and safe [47]. Pleurodesis by autologous blood has been initially used by Robinson, for treatment of persistent air leak in spontaneous pneumothorax patients [48]. This method is being widely used as a treatment of choice for air leaks, since pain and fever, which have been reported with other chemical pleurodesis agents, are rarely encountered with this agent [49, 50]. Development of empyema and tension pneumothorax have been reported, which had occurred due to clotting of the blood in the chest tube and care must be taken to prevent it [50].

In children, the management protocols of pneumothorax remain almost the same. In children too, surgery reduces ipsilateral primary spontaneous pneumothorax recurrence. But, surgery is shown to be predictive for contralateral recurrence in them [51]. Perhaps the positive pressure ventilation required during surgery leads to formation of new blebs contralaterally, or to over-distension of already existing contralateral blebs [52].

5. Anaesthesia

VATS is commonly performed under general anaesthesia with split-lung ventilation. The COPD patient’s baseline pulmonary functions are often suboptimal and they may represent a relative contraindication to split-lung ventilation, thus conferring axillary thoracotomy an advantage over VATS. However, postoperative exacerbation of respiratory function or postoperative chest pain has been more effectively avoided with thoracoscopic surgery [53, 54]. To prevent hypoxemia during one-lung ventilation for thoracoscopic surgery, application of continuous positive airway pressure to the non-ventilated lung is performed [55]. More sophisticated techniques using fiberoptic bronchoscopic segmental oxygen insufflation and recruitment have been reported [56].

Awake surgery under epidural anaesthesia might be advocated in case with several thoracic diseases [57, 58]. Though the efficacy and safety of awake surgery are still controversial, and definitive criteria for indications for awake surgery do not exist, studies have shown that the mean time for chest tube drainage, hospital stay, and operative time were shorter in epidural anaesthesia group than in general anaesthesia group. The postoperative pain score was significantly lower in the epidural anaesthesia group. The study proved that well-maintained breathing and hemodynamics during the awake thoracoscopic surgery attenuated the surgical stress responses and had a smaller impact on the postoperative lymphocyte responses when compared with conventional thoracoscopic surgery under general anaesthesia with single-lung ventilation [59, 60].

Another alternative to general anaesthesia with split-lung ventilation is total intravenous anaesthesia, using propofol and sufentanil, with local anaesthesia, using lignocaine, at incision sites and pleural surface. This has been described to have comparable results, while doing away with the adverse effects of epidural anaesthesia, such as epidural hematoma, spinal cord injury and phrenic nerve palsy. Total intravenous anaesthesia is technically demanding, and anaesthesia-related phenomena, such as hypotension and bradycardia, may arise. Anaesthetists have used laryngeal masks to secure the patients’ airway during the procedure, and provided deep sedation without compromising patient safety [61].

In contrast to secondary spontaneous pneumothorax due to COPD, that caused by lung fibrotic disease shows different characteristics—lungs with fibrotic disease are very fragile and shrunken. The postoperative mortality rate is high (three of 14 patients in one study) due to the exacerbation of basic lung disease and also because full expansion of lung is not achieved by applying negative intrathoracic pressure due to low respiratory compliance [62]. Such a pulmonary fibrotic disease that has taken the centre stage among all diseases, is the COVID-19 disease.

6. Pneumothorax in COVID-19 patients

Lungs of patients with COVID-19 who have significant interstitial involvement seem physiologically small, with low compliance and reduced elastance. The thickened, stiff tissue makes it difficult for lungs to expand properly, and sustained-pressure ventilation may be necessary to obtain acceptable gas exchanges. In this setting, fibrotic parenchyma and preexisting emphysematous blebs are prone to rupture, with consequent risk of pneumothorax. Overinflation and high positive end-expiratory pressure in such fibrotic and hypoelastic lungs may cause alveolar or preexisting bleb rupture.

Furthermore, pneumothorax and bulla have been reported in COVID-19 patients who did not have any risk factors for pneumothorax, including mechanical ventilation, history of smoking, or pulmonary comorbidities [63]. The alveolar damage, and bronchiolar distortion and narrowing, caused by fibrosis following resolution of COVID-19 pneumonia, led to pulmonary bullae formation. Moreover, the severe cough associated with viral infections increases the intrapulmonary pressure. This, in turn, may precipitate bullae rupture and pneumothorax formation [64].

Chest tube placement should be considered first-line treatment. Persistence of air leak may constitute an indication for low-tidal volume two-lung ventilation thoracoscopy. Because of stiffer parenchyma, black cartridge staplers are needed for bulla resection. Ideal timing for surgical procedure is unclear. It may be better to do the procedures early in the disease when the interstitial tissues are less traumatised, less fibrotic, and less inflamed [65].

Extra-corporeal membrane oxygenation (ECMO) as a treatment option for pneumothorax with severe ventilator settings has been tried successfully, to reduce ventilator settings and thus, allowing the lungs to rest. This reduced the lung inflation, and avoided over distension of the lungs, while reducing the air leak and allowing the pleura to heal [66, 67].

7. Conclusion

Pneumothorax is a relatively common malady, both in traumatic and non-traumatic setting. The management is initiated by tube thoracostomy and other supportive measures. Presence of underlying lung disease warrants a more aggressive approach. Prevention of recurrence is also crucial, as recurrences are associated with poorer outcome. VATS is an attractive surgical option due to smaller incision and faster recovery. Innovative procedures continue to be described and many will achieve wide acceptability.