Double lung ventilation Independent lung

ventilation

• Rawan Tawfeek Al Herz Presented by :

Independent Lung Ventilation (ILV) is a rare and technically demanding procedure for managing unilateral lung disease or injury in patients who have failed conventional modes of mechanical ventilation.

ILV can significantly improve aeration of collapsed alveolar segments, increase systemic oxygenation, reduce hypoventilation, and reduce intrapulmonary shunt fraction.

No controlled clinical trials of ILV exist, but multiple case reports have shown it to be a viable option as a rescue ventilator strategy when conventional mechanical ventilation strategies have failed .

ILV techniques permit the isolation of one lung from the other and favor the ventilation of either one or both lungs separately. ILV requires selective control of each mainstem bronchus. Without such separation, both lungs will continue to be treated as a single unit. ILV can be classified as being used for either anatomical or physiological separation of the lungs .

Isolates a diseased lung from contaminating the non-diseased lung. Indications for anatomical lung separation include the management of massive hemoptysis and interbronchial aspiration of copious secretions , as well as whole lung lavage for pulmonary alveolar proteinosis . Typically a short-term emergent intervention to maintain oxygenation and ventilation until definitive therapy can be performed like surgery or embolisation .

Anatomical lung separation

each lung is ventilated as an independent unit after isolating one side from the other. Different ventilator strategies can be used on each side because of asymmetric lung disease resulting in different airway resistance and lung compliance. Unilateral parenchymal lung diseases , postoperative complications of single lung transplants and bronchopleural fistulas are common indications for physiological separation . ILV used as rescue ventilatory support in severe bilateral lung injury remains controversial

physiological lung separation

Independent lung ventilation

Indication

Anatomical lung separation Massive hemoptysis

Whole lung lavage for pulmonary alveolar proteinosis

Copious secretions (e.g. bronchiectasis, lung abscess)

Physiological lung separation

Unilateral parenchymal injury

 Aspiration

 Pulmonary contusion

 Pneumonia

 Unilateral pulmonary edema

Single lung transplant (post operative complications)

Bronchopleural fistula

Unilateral bronchospasm

Severe bilateral lung disease failing conventional ventilation

A variety of methods have been described and used to isolate the lungs . These methods include :

1) Double-lumen ETT (DLT)2) Endobronchial blockers (Bronchial blockers )

Double-lumen endotracheal tube

DLETs are essentially two endotracheal tubes fused together, each with a lumen for ventilating one of the two lungs. DLETs come as left-sided and right-sided tubes to accommodate the different bronchial anatomy encountered in each side

1. The ability to not merely isolate one lung but also to allow differential ventilation to both lungs

2. The ability to apply continuous positive airway pressure (CPAP) to a non-ventilated lung to prevent atelectasis,

3. The ability to more effectively suction secretions, pus, or blood.

Advantages

Insertion of a Double Lumen Tube

1. laryngeal trauma2. bronchial trauma or3. obstruction of one or more of the DLT ventilation ports.4. rupture of the tracheobronchial wall. 5. Mucosal ischemia may occur any time cuff pressure exceeds

Complications

Endobronchial blockers ( bronchial blocker )

The range of endobronchial blockers that are available varies from balloon catheters, such as the Fogarty to custom designed blockers that include the Arndt wire-guided blockers. Fogarty blockers with smaller balloon catheters (0.5 to 3 ml) allow segmental lung isolation to be achieved .

Univent blockers are single-lumen endotracheal tubes with an anterior channel that houses a balloon catheter. The balloon catheter acts as a blocker and the Univent has been shown to be as effective as double-lumen tubes .

Unlike double-lumen tubes, endobronchial blockers add no further complexity to intubation. They are introduced either along the side of a single-lumen endotracheal tube via direct laryngoscopy or into the lumen of the endotracheal tube after intubation. This offers a distinct advantage in the intubation of difficult upper airways .

Bronchial mucosal ischemia, bronchial rupture and pneumothorax are possible side effects of Univent blockers because of the high cuff pressures that can be generated .

The central lumen of the balloon catheter allows a limited amount of suctioning of secretions. Oxygen can also be insufflated through this central lumen into the non-ventilated lung to improve oxygenation.

 1)bronchoscopic visualisation is limited by massive hemoptysis. They cannot be used when the side of the bleeding is unknown.

2)Blocking up the pathological side, it is impossible to monitor continued bleeding or secretions. In pulmonary hypertension, lobar rupture can potentially occur from continued bleeding on the isolated side .

Problems encountered with endobronchial blockers :

Application of ILV requires the use of two ventilators permit the application of different modes of ventilation and different PEEP to each lung. Ventilatory support in ILV can be performed either synchronously or asynchronously .

Application of Ventilatory Support

In asynchronous ILV, the respiratory rate, tidal volume, inspiratory flow, PEEP, FiO2, and even mode of support (controlled mechanical ventilation, intermittent mandatory ventilation, pressure control ventilation, high frequency oscillatory ventilation, continuous positive airway pressure, etc…) can differ from one lung to the other.

In synchronous ILV, the respiratory rate applied to each lung is the same,but the tidal volume, inspiratory flow, PEEP, and FiO2 are selectively titrated to optimize oxygenation and ventilation while minimizing the potential for VILI “Ventilator induced lung injury “ in each lung. As most commonly performed .

Synchronization ensures avoidance of shifting of the mediastinum which can create an obstacle to venous return and resulting fall in cardiac output. Furthermore, the asynchronous insufflation of the lungs may create serious ventilation disorders. These complications occur mostly at low respiratory frequencies (<30 breaths/min).

The tidal volume of each lung can be set at 50% of the calculated tidal volume of the total lungs or two thirds of the tidal volume can be applied to the more diseased lung and one third to the less affected lung. Appropriate PEEP is applied to each lung. Ventilation of the two lungs is regulated according to the compliance, respiratory airway resistance, end tidal CO2 from each lung and central venous pressure. Inspired flow of oxygen (FiO2) and ventilatory parameters are adjusted as indicated by the clinical condition and blood gas measurement.

The problem of humidifying and heating the ventilated gases and difficulty in bronchosuctioning remains considerable and can lead to severe hypoxemia and hypercarbia.

Cases

a 57 year old male with a past medical history of persistent cough for 2 years, hemoptysis and emphysema. He has smoked for the past 30+ years. He was transferred from another hospital with a Spo2 of 50% on a 100% non-rebreather.

His blood gas, on a 100% non-rebreather was :

After admission he became increasingly more hypoxic and hemodynamically unstable and was intubated with a single lumen 8.0 Endo-tracheal tube.

A chest x-ray revealed an opacification of the right lung with a mediastinal shift. A spiral CT of his chest, revealed a large right mainstem lesion, which was occluding his right mainstem bronchus.

Mode : Pressure control 35 cm H20, PEEP 15 cm H2O, rate 14 bpm, Fio2 1.0, inspiratory time 1.5 sec and tidal volumes about 900 ml. ABG’s still revealed severe hypoxia and a CXR revealed a hyperinflated left lung

Upon his return to the MICU he was placed on

It was decided to start Nitric Oxide (NO) at 20 ppm for 30 minutes and to change to a Drager Evita XL Ventilator

PCV+ 25, PEEP 5 cm H2O, rate 14 bpm, Fio2 1.0, inspiratory time 1.0 sec and tidal volumes of 400-500ml.

Right lung: APRV P high 44 cmH2O/P low 3 cmH20, T high 6sec/T low 5sec

Left lung: PCV+ 25, PEEP 5 cmH2O, rate 20 1.0 sec inspiratory time and tidal volumes of 400-500ml. At one hour after initiating ILV the ABG’s were

After 30 min of NO therapy ABG’s revealed

The NO was discontinued and the patient was then intubated with a 39 French double lumen endobronchial tube to protect the left lung and to selectively ventilate the right lung. Asynchronized ILV was initiated utilizing two Drager Evita XL ventilators.

Figure 2 CXR 2 After ILV

Significance of the case: Independent Lung Ventilation (ILV) appeared to be valuable in re-expanding this patient’s right lung after other interventions failed to improve the lung collapse. As a result, this patient was more effectively ventilated and oxygenated. 

Figure 1 CXR 1 Before ILV

CXR revealed a hyperinflated right lung

A 69-year-old man, with a 40-pack-year history of smoking and known chronicobstructive pulmonary disease, presented with chest pain and dyspnoea.

A chest radiograph showed right-sided pneumothorax following rupture of a large apical emphysematous bulla. This was decompressed by insertion of two intercostal catheters. However, he had a massive air leak associated with increasing subcutaneous emphysema, which necessitated transfer to other hospital for surgical correction of the air leak (Figure 1A).

Following induction of anaesthesia, a left-sided 39 Fr double-lumen tube was inserted, and video-assisted thoracoscopy and partial right upper lobectomy were performed, with excision of the bulla. BioGlue (10mL) was also applied. The patient was returned to the intensive care unit intubated, where he was initially ventilated conventionally with synchronised intermittent mandatory ventilation (SIMV) volume control due to the difficult airway and extensive subcutaneous emphysema

In the ICU, the air leak persisted despite strategies tominimize mean airway pressure, including low tidal volume, zero positive end-expiratory pressure (PEEP) and attempts at spontaneous breathing. A postoperative chest x-ray showed a collapsed right lung. As this was associated with rapidly worsening oxygenation, respiratory acidosis and anongoing large air leak (Figure 1B), it was decided to reinstitute independent lung ventilation.

B. Chest x-ray after attempted surgical correction of the air leak, showing collapse of the right lung with opacification of the right apical region from BioGlue, a right-sided chest drain, gross hyperinflation of the left side and extensive subcutaneous emphysema.

A left-sided 39 Fr double-lumen tube was placed and, after effective lung separation was confirmed, asynchronous independent lung ventilation was

instituted with two ventilators (Puritan Bennett 840, Puritan Bennett Corporation, USA). Positive end-expiratory pressure and mean airway pressure

were minimized on the affected lung, which reduced the air leak, leading to closure of the fistula over 48 hours. The parameters for ventilation of the left lung, which was also emphysematous, were optimised for oxygenation and

ventilatory needs while minimising the risk of barotrauma

When ventilation was adequately established, bronchoscopy was performed through the double-lumen tube, allowing removal of copious bloody material from the right main bronchus, facilitating re-expansion

and improved compliance of the right lung. Sedation and neuromuscular paralysis were maintained during this time with

propofol, fentanyl and vecuronium infusions.

They replaced the double-lumen tube with a single-lumen endotracheal tube after 24 hours, as the respective lung compliances equalised. The patient was successfully extubated on the third postoperative day and

was discharged home .

A 40-year-old man underwent left-sided single-lung transplantationfor advanced usual interstitial pneumonitis. His immediate postoperative course was unremarkable, and he was discharged home soon afterwards. On Day 94 postoperatively, he developed progressive respiratory distress associatedwith an acute haemorrhage in the native lung and soiling of the transplanted lung (Figure 2). The bleeding was attributed to a combination of coagulopathy secondary to haemolytic uraemic syndrome/thrombotic thrombocytopenic purpura (HUS/TTP)-like syndrome (probably triggered by immunosuppression with everolimus) and invasive aspergillosis .

Chest x-ray on Day 94 after left-lung transplantation, showing fibrosis of the right lung, with evidence of alveolar consolidation of the native and the transplanted left lung.

The patient was intubated and ventilated with SIMV volume control after an unsuccessful trial of non-invasive ventilation. Cessation of everolimus, initiation of antifungal therapy (caspofungin and voriconazole), plasma exchange pulse corticosteroid therapy and correction of coagulopathy (with fresh frozen plasma, cryoprecipitate and recombinant coagulation factor VIIa [eptacog alfa]) failed to stop the ongoing bleeding. Attempts at embolisation of the bleeding bronchial artery were aborted when an abnormal communication with the right vertebral artery was detected. With progressive soiling of the transplanted lung and worsening oxygenation, lung separation was achieved with a right-sided double-lumen tube, and the lungs were differentially ventilated. The ventilator settings and arterial blood gas parameters just before beginning independent lung ventilation and the initial settings for independent lung ventilation are shown in Table 2.

With effective anatomical lung separation and ventilator strategies tailored for each lung, the compliance of the transplanted lung improved demonstrably over 2 days. Bronchoscopic examination was performed every 6 hours for the first 24 hours, to confirm the position of the doublelumen tube and for airway toilet. Inhaled nitric oxide (20 ppm) was administered to the transplanted lung during the initial period of severe hypoxaemia. Increased concentrations of inspired oxygen to the native lung achieved minimal improvement in systemic oxygenation (evidenced by a rise in the PaO2 of less than 10mmHg with FIO2 of 0.21–1.0), confirming minimal gas transfer function of the diseased lung.Subsequent bronchoscopy revealed ongoing bleeding of the native

lung. A right-sided pneumonectomy was performed 3 days after the institution of independent lung ventilation. The patient was successfully weaned from mechanical ventilation over the subsequent 2 days. After extensive physical rehabilitation for critical illness weakness, he was discharged home and continued to have good graft function 11 months after discharge.

These cases are a reminder that independent lung ventilation may be a successful treatment when pulmonary disease is markedly asymmetrical or when the pathological process in one lung adversely affects the other .

ILV is usually instituted as rescue therapy . Prevention of contamination of the unaffected lung by secretions or blood may involve endobronchial blockade or selective double-lumen tube ventilation. Physiological lung separation is used when mechanics and ventilation/perfusion ratios are very different between the two lungs. In such instances, application of uniform ventilatory support, such as PEEP, inspiratory flow rate, respiratory rate and tidal volume, may be injurious to one lung even if beneficial to the other.

The limitation of the current data is that they are confined to case reports and series with no prospective, systematic investigations in the intensive care unit available.

Any decision to institute ILV must account for the expertise required in double-lumen tube/endobronchial blocker insertion, skilled and intensive nursing, specialised monitoring and ready availability of fibreoptic bronchoscopy . Complications associated with ILV are usually related to either double-lumen tube intubation or endobronchial blocker placement or the inadvertent loss of functional separation. These technical requirements and potential complications must be carefully weighed against any perceived benefits before proceeding with ILV.

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