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The who, where and what of anaesthesia for interventional bronchoscopy – an attempt to redefine our answers based on recent guidelines and advances

By September 7, 2019volume2-issue1
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Anand Murugesan et al.: The who, where and what of anaesthesia for interventional bronchoscopy – an attempt to…..

Review Article

The who, where and what of anaesthesia for interventional bronchoscopy – an attempt to redefine our answers based on recent guidelines and advances

Anand Murugesan1 and Indumathi.D2

1Senior Consultant, Department of Anaesthesiology, Apollo hospitals, Greams road, Chennai. 2Associate Consultant, Department of Anaesthesiology, Apollo hospitals, Greams road, Chennai.

ABSTRACT:

Interventional bronchoscopy has evolved from simple office based bronchoscopies done under local anaesthesia or conscious sedation to state of the art bronchoscopy suite based practice equipped for complex interventions requiring intense monitoring and general anaesthesia. New advances in the field of anaesthesiology such as the laryngeal mask airway, short-acting anaesthetics with minimal effect on respiratory function and mechanical jet ventilators are well suited for interventional bronchoscopy procedures.
Keywords: Interventional bronchoscopy, Bronchoscopy suites, conscious sedation, Laryngeal mask airway, jet ventilation.

Corresponding Author: Dr. Anand Murugesan, Senior Consultant, Department of Anaesthesiology, Apollo hospitals, Greams road, Chennai

How to cite this article: Anand Murugesan and Indumathi. D, The who, where and what of anaesthesia for interventional bronchoscopy – an attempt to redefine our answers based on recent guidelines and advances, JAPT 2019:2(1):18-21

Introduction

It is imperative to improvise our protocols to cater to the ever expanding scope of interventional bronchoscopy by incorporating newer anaesthesia drugs and equipment. This article tries to answer some of the common questions pertaining to anaesthesia.

Who Should Perform and Where?

The major limitations of local anaesthesia is its inability to reduce the patient’s anxiety and [1,2] a maximum allowable dose, especially in patients with hepatic and renal issues [3]. Thus, conscious sedation with anxiolytics, with or without opioids, combined with local anaesthesia, has become the preferred form of anaesthesia for diagnostic bronchoscopy procedures [4]. These sedations are performed by the pulmonologist or a trained anaesthesia nurse, in most institutions.

However, conscious sedation has limitations like, doses required to achieve the desired effect vary widely among patients, complications like hypoventilation, hypoxemia,loss of airway patency, and hemodynamic instability. The interventionalist has to manage these complications,or abandon the procedure [5]. Recovery related issues delay discharge and result in unplanned hospital admission [6] which increases the financial burden on patients.

Also, patients with multiple comorbidities warrant close monitoring during and after the procedure thus reinforcing the need for an anaesthesiologist even if it is done under local anaesthesia. Many hospitals have realised the need for dedicated bronchoscopy suite with updated anaesthesia equipment, oxygen, air, and suction ports, scavenging system, equipment for management of emergency situations, and can double up as operating rooms [7].

The American College of Chest Physicians in 2003 gave a non specific recommendation, that ‘all procedures may be performed using local anaesthesia with or without conscious sedation or using general anaesthesia as indicated by the applicable guidelines in a particular practice environment (p. 1694). ‘However, general anaesthesia was recommended for rigid bronchoscopy and for pediatric bronchoscopic procedures’ [8].

The European Respiratory Society and the American Thoracic Society on interventional pulmonolgy in 2002 (ERS/ATS) was more specific, and stated that ‘Although several procedures can be performed by flexible bronchoscopy with local anaesthesia and conscious sedation, the interventional bronchoscopist should be prepared to convert to general anaesthesia, if the situation requires (p. 358)’. The ERS/ATS also recommended that the design of the bronchoscopy suite should account for the presence of anaesthesia equipment [7].

What type of Anaesthesia ?

Patient Factors

Patients with ASA score above 2, acute illness, and low room air oxygen saturation and low Pao2 and high Pa co2 in ABG are less likely to tolerate the transient hypoxia associated with bronchoscopy [9]. General anaesthesia with ultra-short-acting drugs like propofol or volatile anaesthetic agents like sevoflurane allow rapid recovery and return to baseline respiratory parameters[10] without need for post procedure ventilation.

Airway Factors

Central airway obstruction, severe hemoptysis, Obesity, Obstructive sleep apnea, can cause respiratory distress or failure with acute loss of airway patency during a bronchoscopy procedure under conscious sedation. General anaesthesia with LMA or ETT is ideal for such patients [9]

Procedural Factors

Rigid Bronchoscopy

General anaesthesia with muscle relaxation, with spontaneous assisted ventilation , or jet ventilation avoids hypoxia and hypercapnia[11,12] and airway injury[8] due to scopy. EBUS. The procedure can be quite lengthy as small lymph nodes and multiple lymph node stations are sampled [13]. Movement or coughing during the procedure can be risky because of proximity to great vessels, thus general anaesthesia and muscle relaxation is ideal. LMA is commonly used as EBUS requires a large calibre FOB and using the same through an ETT can result in high airway pressures and inadequate ventilation.

Pleuroscopy

Lateral position with diseased side nondependent is not well tolerated by patients. Also, there is a risk of lung injury when a rigid thoracoscope is introduced, more so if the patient is coughing or dypneic. Thus general anaesthesia with muscle relaxation is ideal.

Cryotherapy

The cryo probe requires insertion of a large diameter FOB and the cryo probe can cause damage to the tracheal mucosa when it is being withdrawn. Thus general anaesthesia with muscle relaxation via an ETT large enough to allow adequate ventilation (minimum 8mm) or LMA where such a large ETT cannot be used as in females or tracheal lesions is preferable.

Flexible Bronchoscopy

Local anaesthesia alone in cooperative patients or conscious sedation with midazolam with or without Fentanyl along with Local anaesthesia in uncooperative and paediatric patients. Monitored anaesthesia is preferred in ASA 3 and above patients is preferable.

Thermoplasty

Most of the patient coming for thermoplasty have florid wheeze, reduced lung compliance ,high airway pressures and are prone to intra and post procedural bronchospasm, inability to ventilate, hypoxia, pneumothorax and even tension pneumothorax with hemodynamic collapse. General anaesthesia with muscle relaxant is the preferred technique.

Anaesthetic Agents and Equipment

Propofol is superior to midazolam due to its short onset time of 30 s, rapid recovery time, better neuro psychometric recovery [6] reduce coughing and the depression in ciliary function [14] as well as the release of cytokines and the stress hormone response [15,16].

Remifentanil is the shortest acting opioid available with duration of action of 3–10 min and rapid onset of action (1 min), also blunts airway reflexes during the procedure with no residual effect in the recovery room [10].

Ketamine induces a dissociative state in which sensory stimuli are blocked from reaching the cerebral cortex with associated amnesia and analgesia, analgesic property makes it a good adjunct to propofol [17] with bronchodilating properties without causing respiratory depression. Dexmedetomidine is an alpha-2 agonist which provides sedation and analgesia without causing respiratory depression [18], with cardioprotective benefits by lowering perioperative oxygen consumption, and the stress response. [19].

Laryngeal Mask Airway

The laryngeal mask airway (LMA) is placed above the level of the vocal cords, allowing inspection of the entire airway [20] and is preferred over ETT in tracheal stenosis or tumors to avoid trauma [21]also allows introduction of large therapeutic bronchoscopy as required for EBUS or Cryptography, without interfering with ventilation[22].

Newer resusable LMAs like the Ambu aura have a large airway tube which is ideal for EBUS. Ambu aura gain has a gastric suction port which can be used to deflate stomach contents. I gel is a singe use LMA which adapts to the shape of the oral cavity can also be used. In obese patients, the Proseal LMA offers the advantage of lower ventilation pressure with an additional gastric suction port.

Mechanical Jet Ventilation

Mechanical jet ventilators control the respiratory rate, inspiratory time, driving pressure, humidify the inspired oxygen up to 100% preventing without airway mucosa dryness and necrosis or damage to ciliary function [24] and has two alarm systems to protect against barotrauma.

Conclusion

The field of interventional bronchoscopy has evolved tremendously and with it anaesthesia too has evolved with focus on enhanced recovery after anaesthesia (ERSA) and fast tracking by using ultra short acting drugs, careful patient selection, safe anaesthesia practice and effective communication between pulmonologist and anaesthesiologist during planning and administration of anaesthesia.

Acknowledgement

We thank the management of Apollo Hospitals, Greams Road, Chennai for their support to our department.

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