|Year : 2023 | Volume
| Issue : 3 | Page : 85-93
Flexible bronchoscopy in pediatric intensive care unit
Krishan Chugh1, Neetu Talwar1, Manish Kori1, Kaustubh Mohite2, Mahesh Mohite3
1 Department of Pediatric Intensive Care and Pulmonology, Fortis Memorial Research Institute, Gurugram, Haryana, India
2 Department of Pediatric Pulmonologist, Sai Children's Hospital, Panvel, Maharashtra, India
3 Department of Pediatric Pulmonologist, Sai Children's Hospital, Panvel; Department of Pediatric, BJ Wadia Children Hospital, Mumbai, Maharashtra, India
|Date of Submission||22-Apr-2023|
|Date of Decision||04-May-2023|
|Date of Acceptance||07-May-2023|
|Date of Web Publication||19-May-2023|
Dr. Krishan Chugh
Fortis Memorial Research Institute, Gurugram - 122 002, Haryana
Source of Support: None, Conflict of Interest: None
Flexible bronchoscopy (FB) is a very rewarding procedure in the evaluation and management of appropriately selected children with respiratory issues in pediatric intensive care unit (PICU). An understanding of the alterations in respiratory physiology (airway resistance, compliance, and air exchange) during FB is absolutely essential for the safety of the child. To reduce discomfort and other side effects of FB it is necessary to optimize the condition of the child including sedation, analgesia, paralysis, ventilator settings, and cardiovascular status. With advancements in technology and instrumentation many interventional procedures can be performed safely and effectively using access to the airway through the endotracheal tube, tracheostomy tube, or Laryngeal Mask Airway (LMA). Close monitoring during and after FB minimizes complications.
Keywords: Bronchoalveolar lavage, flexible bronchoscopy, neonatal intensive care unit, pediatric intensive care unit
|How to cite this article:|
Chugh K, Talwar N, Kori M, Mohite K, Mohite M. Flexible bronchoscopy in pediatric intensive care unit. J Pediatr Crit Care 2023;10:85-93
|How to cite this URL:|
Chugh K, Talwar N, Kori M, Mohite K, Mohite M. Flexible bronchoscopy in pediatric intensive care unit. J Pediatr Crit Care [serial online] 2023 [cited 2023 Jun 2];10:85-93. Available from: http://www.jpcc.org.in/text.asp?2023/10/3/85/377436
| Introduction|| |
Flexible bronchoscopy (FB) is a cruise through the tracheobronchial tree. Real-time evaluation of the airways in 3 dimensions makes it an invaluable tool for the diagnosis of conditions such as tracheomalacia, bronchomalacia, tracheo esophageal fistula, mucus plugs, and many more indications, which would otherwise be left unconfirmed. In a recent multicentric pediatric intensive care units (PICU) study, in 87.2% of the patients, positive contribution of FB was identified.
And in today's age, we have entered a whole new world of interventional pulmonology, wherein therapeutic interventions such as removal of foreign bodies, balloon dilatation of stenotic segments, intrabronchial instillation of glue, removal of mucus plugs, and such other techniques are possible.
To a novice, a bronchoscopy done in the intensive care setting where many of the patients are intubated would be so very exciting and deceptively easy. After all, there is no maze of upper airway to be decoded, no esophagus eagerly lying in wait to be entered by default, coughing or agitation, no embarrassments to be faced when the scope does not enter the glottis in a few attempts. However, the fact remains that especially in these high-risk patients, one has to be absolutely sure of the justification of the procedure, since bronchoscopy is an invasive procedure, which invariably interferes with a lot of physiological processes.
| Characteristics Of Critical Care Setting|| |
Patients in the PICU or neonatal intensive care unit (NICU) usually are critical, very often with some degree of respiratory compromise requiring mechanical ventilation invasive or noninvasive. The procedure of FB, poses a challenge in these children because the airway is going to be obstructed for that short duration even if the smallest of bronchoscopes is used, which may not be easily tolerated by the patient.
The insertion of flexible fiberoptic bronchoscopy (FFB) into the trachea causes partial obstruction of its lumen depending on the size of the bronchoscope. In adults the trachea is approximately 20–25 mm in diameter, whereas the diameter of flexible bronchoscopes generally does not exceed 6.3 mm. In contrast, the tracheal diameter ranges from approximately 2.5 mm in premature babies to 5–10 mm in toddlers and young children. Hence airway compromise is significant in the pediatric age group. This is worsened in cases with artificial airway – endotracheal tube (ET) or tracheostomy tube. This not only makes ventilation difficult but also makes the procedure technically difficult, since the maneuverability of the bronchoscope is affected by the tubes as well as their curves.
| Bts Recommendations on Flexible Bronchoscopy in Intensive Care Unit|| |
- Risk assessment. Critically ill children often have hypoxia, electrolyte disturbances, clotting abnormalities, and arrhythmias. Hence, one needs to reconfirm the necessity of doing a bronchoscopy and its expected benefits versus risk ratio
- Patients in ICU should always be considered at high risk for complications when undergoing fiberoptic bronchoscopy. Continuous monitoring during and after the procedure is recommended. This should include:
- Electrocardiography (ECG), continuous intra-arterial blood pressure or intermittent noninvasive blood pressure measurement, pulse oximetry (SpO2), with appropriately set alarm
- Adverse events require immediate withdrawal of the bronchoscope and resuscitation and stabilization of the patient. Only after this, one needs to decide whether the procedure has to be continued or aborted
- Monitoring intracranial pressure (ICP) in case of head injury is essential if sudden rises in ICP are to be avoided due to CO2 retention or other causes
- Monitoring endotracheal CO2 in such patients may also help to detect falls in minute ventilation caused by the presence of the bronchoscope within the ET.
| Pathophysiological Effects Of Flexible Fiberoptic Bronchoscopy|| |
FFB is by definition, an invasive procedure that may cause or trigger a series of undesirable responses from several organs.
Effects on lung mechanics
During bronchoscopy, the most important effect is the increase in airway resistance (Raw) that results from the airway obstruction.
Increase depends on other factors as well like length of the tube. In an intubated and mechanically ventilated patient, increase in Raw will affect pressures, both peak inspiratory pressure (PIP) and the positive end-expiratory pressure (PEEP), as well as the tidal volume (TV) that is delivered to the patient. The parameters affected and the extent to which they are affected depends both on the size of the bronchoscope in relation to the size of the airway as well as on the mode of mechanical ventilation. These pressure changes increase the risk for an air leak especially in patients with obstructive lung disease and significant air-trapping. They may also cause significant hemodynamic instability in patients with impaired cardiovascular function.
The profound effects that bronchoscopes of different sizes have on various parameters of ventilation both in normal and diseased lungs have been demonstrated in various studies.,
- If pressure-controlled (PC) ventilation is used, TV decreases significantly
- In volume-controlled (VC) mode, the TV is maintained with the PIPs rising dramatically. The auto– PEEP also rises
- Pressure control ventilation has little effect on the pressures but it may severely limit the delivered TV and thus may lead to significant respiratory decompensation
- Among the two modes, VC was preferred because of the more consistent TV, which it provides
- As the bronchoscope–ET diameter difference decreased, PIP and auto-PEEP increased
- As a general guideline, to maintain TV >50% of baseline during PC ventilation, and to prevent PIP from increasing >20 cm water, bronchoscope– ET diameter difference should approximately >1.3 mm for infants and toddlers, >2.0 mm for small children, and young adolescents and >2.5 mm for older adolescents/young adults
- These changes were similar both in the normal and diseased lung.
Changes in lung compliance
During FB, suctioning as well as instillation of normal saline for the collection of bronchoalveolar lavage (BAL) is done frequently. This results in atelectasis and washing out of surfactant leading to significant changes in lung compliance.
Considering that patients in the ICU tend to have conditions associated with very low lung compliance (e.g., acute respiratory distress syndrome, pneumonia, and atelectasis), an additional decrease may have severe repercussions.
Effects on gas exchange
Transient deterioration of gas exchange occurs during FFB because of the partial obstruction of the airway. Hypoxemia is probably the single most common gas exchange abnormality. This could be due to atelectasis due to the decrease in TV resulting from the depletion of intra-alveolar oxygen due to frequent suctioning during the procedure.
The other reason is the instillation of normal saline used for the BAL that washes out surfactant and causes localized “flooding” of the alveoli.
Hypercapnia results from hypoventilation caused by the airway obstruction, which can't be compensated by increasing the respiratory rate or TV on the ventilator.
Usually, this does not cause any harm, except in two kinds of patients: those with pulmonary hypertension and those with cerebral edema. Hypercapnia may result in acute and severe pulmonary vasoconstriction in the former, thus raising the already increased pulmonary vascular resistance and worsening the pulmonary hypertension. In the latter case, hypercapnia causes cerebral vasodilatation leading to worsening of the cerebral edema.
Bronchoscopy may cause significant cardiac or hemodynamic changes by indirect mechanisms, including changes in the vascular tone caused by hypoxemia and/or hypercapnia, as well as changes in the intrathoracic pressure (especially during coughing episodes) that may affect the venous return and/or the afterload of the left ventricle.
Finally, increases in heart rate and systemic blood pressure may be caused by anxiety and discomfort often associated with the procedure. These changes may not be significant in those without any cardiac problems. But may prove to be deleterious in those with a compromised cardiac function, increased systemic blood pressure or increased ICP.
Increase in PEEP can have profound effects on cardiac output. Last but not least is the increase in central venous pressure caused by high PEEP that in turn may cause a significant increase in the ICP.
| Indications of Bronchoscopy in Pediatric Intensive Care Unit/Neonatal Intensive Care Unit|| |
FB is used as the procedure of choice in intensive care units for various reasons. Depending on the hemodynamic stability of the child and the mode of ventilatory support, FB can be performed through nose, laryngeal mask inlet (LMA), or ET. The most common reason for performing FB in PICU is for obtaining bronchoalveolar lavage (BAL) sample. Based on the site of pathology guided by radiological imaging (X-ray, CT scan), the BAL sample can be obtained from the localized site and sent for microbiological evaluation. X-ray findings of atelectasis or hyperinflation can be assessed using FB. Airway assessment stays the other important indication in cases of persistent noisy breathing caused by stridor or wheeze. Conditions such as laryngomalacia, subglottic stenosis, vocal cord paralysis, hemangioma, and laryngeal anomalies (cyst, web, cleft) can cause persistent inspiratory stridor. Lower airway anomalies such as tracheomalacia, tracheoesophageal fistula, bronchomalacia, impacted foreign body, airway stenosis, granuloma, endobronchial tumor, and thick mucus impaction may cause or exacerbate the underlying pulmonary pathology. Non-infective pulmonary causes such as pulmonary hemorrhage, sarcoidosis, aspiration pneumonia, and lipoid pneumonia may give characteristic features on BAL sample. Compromised airway lumen due to external occlusion by lymph nodes or vascular structures can be assessed using FB in intensive care.
Various modalities to clear the airway lumen of intrinsic occlusion help improve the ventilation of the child in critical care. The suction of thick mucous impaction, debridement of granuloma or endobronchial tumor or retrieval of the aspirated foreign body helps clear the airway lumen. Balloon dilatation can be done in cases of congenital or acquired causes of airway stenosis. Persistent bleeders from airway mucosal surface can be controlled using argon plasma coagulation and cryotherapy. FB can be used as an accessory procedure in cases of difficult intubation, difficult extubation, and selective lung ventilation. In cases with anatomical airway malformation, a self-expanding metallic stent can be deployed with the assistance of FB in operation theater.
| Role Of Flexible Fiberoptic Bronchoscopy in Ventilator-Associated Pneumonia|| |
Children on the ventilator often develop new opacities in their lungs when on the ventilator, especially when ventilation is prolonged. Identifying the causative organism of ventilator-associated pneumonia (VAP) and choosing the appropriate antibiotic can be crucial. Endotracheal suction, blind bronchial sampling (BBS), “blind” BAL and FFB-assisted BAL are the techniques employed for obtaining the “secretions” from the lower airways. In a study, we (KC) compared these four techniques in children with VAP. Blind BAL was the most reliable method followed closely by blind bronchial sampling for the diagnosis of VAP. Considering the difference of the cost in the two procedures, blind bronchial sampling may be the preferred method in the PICU of a developing country.
| Sedation For Flexible Bronchoscopy|| |
Bronchoscopy is usually associated with anxiety, which can cause significant hemodynamic variations like increases in blood pressure and heart rate. These may prove to be catastrophic in a critically ill child. Hence, additional doses of narcotics and/or benzodiazepines could be used just before the starting the procedure. Various options are discussed below. Nil per oral requirements as per the ASA recommendations is followed.
General anesthesia (GA) is generally not used during flexible fiberoptic bronchoscopy (FFB) procedure in majority of the centers. Exceptions are interventions such as transbronchial biopsies or dilatation of subglottic stenosis etc., Local anesthesia using lidocaine instillation facilitates the procedure and helps reduce the need of deeper sedation. In newborns and infants, the procedure is feasible without sedation, particularly if evaluation of upper airway anatomy and movements is the indication for procedure.
Premedication and analgesia/sedation during procedure
Premedication with a sedative is commonly used before the procedure at many centers. However, FFB has been performed at other centers without any premedication also.
Several choices are available for sedation and analgesia for FFB in children and neonates [Table 1]. Although standard doses are known, the usual practice is to give a smaller dose initially and titrate the further doses according to the need.
|Table 1: Sedation and analgesia for flexible fiberoptic bronchoscopy in children|
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It has been suggested that fentanyl, either alone or in combination with midazolam, should not be given to infants younger than 3 months of age for fear of respiratory depression or chest wall rigidity.
- Apart from local instillation of 2% lidocaine spray, injection atropine and glycopyrrolate are kept ready in anticipation of increased secretions due to irritation of the mucosa and due to drugs like ketamine.
- Analgosedation approach is preferred. Injection fentanyl or ketamine are most commonly used drugs along with midazolam and propofol. Dexmedetomidine is another safe option as it preserves the respiratory drive to a greater extent. A combination approach is used to avoid higher doses of the individual drugs. Paralysis may be required to facilitate endotracheal intubation. If ET is in situ, usually procedure can be completed without paralysis.
Various drugs used and their main features are summarized below:
- Ketamine-(N-Methyl-D-aspartate receptor antagonist) combination with propofol can achieve adequate analgosedation depth with maintenance of spontaneous breathing. Increased airway secretions are a limiting factor, which maybe reduced by premedication with atropine
- Fentanyl-synthetic opioid is used in combination with Midazolam or propofol. Its rapid bolus should be avoided
- Morphine-generally avoided due to the availability of fentanyl which has a better safety profile
- Propofol simplifies sedation for bronchoscopy and makes it safer by effectively suppressing respiratory reflexes with a favorable context-sensitive half-time
- Midazolam-rapid onset, short duration of action, and retrograde amnesia are useful features
- Dexmedetomidine-selective alpha 2 agonist, has been used in combination with fentanyl/remifentanil with adequate sedation and safety profile.
It is advisable to have a dedicated sedation team for the procedure. Bronchoscopist-administered sedation may be associated with longer procedure time and increased risk of adverse effects. Mondal et al. compared the safety, time efficiency, and cost-effectiveness of FB performed under bronchoscopist administered moderate sedation (BAMS) versus GA in children. The study found that FB under BAMS had lower costs and fewer procedural complications compared with FB under GA, but the safety of BAMS could not be conclusively established.
The sedation-agitation scale can be used to guide sedative dosage in conscious sedation before bronchoscopy in children, minimizing adverse reactions and improving the operating experience.
The laryngeal mask airway (LMA) is a device used as an alternative to the facemask and ET for airway support in children undergoing diagnostic FB [Figure 1]. It consists of a flexible tube attached to a small elliptical silicone mask with an inflatable outer cuff and is designed to sit in the hypopharynx, forming an airtight seal around the laryngeal inlet when the cuff is inflated. The LMA allows for the use of larger flexible bronchoscopes, providing greater illumination and sharper images of the laryngotracheal structures. LMA is connected to a Dual-Axis Swivel Adapter to facilitate the introduction of the bronchoscope [Figure 2]. [Figure 3] depicts the assembly of the adapter with the LMA. [Table 2] provides an estimate of LMA size selection as per the weight category of the child.
Accidental dislodgement of the ET/LMA during the procedure can cause respiratory and hemodynamic changes and be dangerous for critically ill patients. Therefore, it is recommended to have an assistant hold the ET/LMA firmly in place to prevent it from being dislodged during insertion, withdrawal, or maneuvering of the bronchoscope. The assistant can also help position the patient's head and straighten the ET/LMA if needed.
Ventilator management-Patients on mechanical ventilation require certain adjustments to their ventilator settings during bronchoscopy. Here are some key guidelines
- Fraction of inspired oxygen: Give 100% oxygen throughout the procedure to avoid desaturation
- Respiratory rate: Increase the ventilator rate when heavy sedation or muscle relaxation is used. Decrease the frequency and/or TV when bronchoscopy is performed through a narrow airway to allow complete exhalation
- PEEP: Decrease PEEP by 50% in patients who have an air leak or would be adversely affected by raised PEEP (e.g., patients who have undergone Glenn or Fontan surgery). In patients already receiving very high PEEP (>10 cm H2O), it may be necessary to adjust PEEP
- TV: Maintaining a TV within a reasonably optimum range can be challenging. The safest and most efficient way to ventilate critically ill patients is by manual ventilation using a prolonged inspiratory time and the lowest possible respiratory rate
- Adaptor/connector: Use a double swivel adapter/mount catheter connected to the ET or LMA to allow manual ventilation to continue. Use an adaptor with a “slit diaphragm” to provide an optimal seal around the bronchoscope and reduce air leaks.
The advantages of muscle relaxation include easier procedure for the bronchoscopist and prevention of sudden movements, labored breathing due to partial obstruction of the airway, and harmful coughing. However, the disadvantages are that airway dynamics cannot be assessed and evaluated, which may hinder the diagnosis of conditions such as laryngomalacia and tracheobronchomalacia.
To minimize risk in high-risk cases with limited respiratory capacity, non-invasive ventilation should be initiated before FB to help recruit atelectatic areas and prevent further atelectasis. We recommend using a laryngeal mask airway (LMA) during the procedure in these cases.
| Mobile Videobronchoscopy|| |
A mobile bronchoscopy unit permits the procedure to take place in any part of the hospital. A mobile cart needs to be equipped with a bronchoscope, light source, ECG monitor and a pulse oximetry, video equipment, and a suction device. The basic accessories (forceps, brushes, and mucus traps) should also be stored in the cart along with the basic resuscitation equipment (ETs, laryngoscopes, suction catheters, and ventilation bag).
In our hospital, we have a video bronchoscope with a small screen [Figure 4], which is, battery operated and is equipped to take and store images and can be easily taken to the PICU, post– op theatres, and cardiac ICU for a quick bronchoscopy. No mobile cart is needed as all the other equipment other than a swivel adapter and mount catheter is present in such areas.
| Disposable Bronchoscopes|| |
Disposable bronchoscopes are now available which are light, cheaper, and easily transportable to the PICU/NICU from the bronchoscopy suite or can be stationed in the PICU itself. The picture/video is available on a small screen of the size of a tablet. A complete examination of the airways as well as BAL can be done through these scopes.
| Contraindications|| |
Contra-indications of flexible bronchoscopy
There is no absolute contraindications of FB. However, FB should be performed with caution in case of severe hypoxemia, hypotension, and pulmonary hypertension. American Thoracic Society has given criteria in adults for contraindication on FB which could be extrapolated in the pediatric age group. These include noncorrectable hypoxemia (partial pressure of oxygen (PaO2) <75 mmHg), PaO2/FiO2 <150, or oxygen saturation <90% with supplemental oxygen. Severe thrombocytopenia and coagulopathy stay a relative contra-indication for FB.
| Complications Of Flexible Bronchoscopy|| |
The most frequent complication post-FB includes hypoxemia with or without hypercapnia, laryngospasm, and bronchospasm, as well as cardiac arrhythmia and bradycardia.
Injury and friction caused by FB may cause epistaxis, hemoptysis, pneumothorax, broncho-pleural fistula, or postbronchoscopy subglottic edema.
These complications are purely dependent on the disinfection and cleaning practices carried by a unit and can be prevented by following set protocols.
Life-threatening complications such as drug overdose causing excessive respiratory depression, improper medication and inadequate monitoring postsedation should be kept in mind while performing FB.
Fever is the most common complication in 24 h post-BAL aspiration by FB. It has been attributed to release of cytokines and transient bacteremia. Some of the pathological conditions encountered in the PICU are shown in [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12], [Figure 13], [Figure 14], [Figure 15], [Figure 16], [Figure 17], [Figure 18].
|Figure 5: Vallecular cyst. Red arrow shows the Vallecular cyst just above and anterior to the epiglottis|
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|Figure 6: Laryngeal web. A closure view in the right picture shows that the web is thin and membranous|
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|Figure 10: Laryngomalacia. Glottic opening can be seen during expiration in the left picture while it closes as the epiglottis folds on to itself and the arytenoids fall over the glottic opening during inspiration as seen in the right picture|
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|Figure 11: Evaluation of tracheostomy. Granulation tissue in subglottic area above the tracheostomy stoma as seen in a closure view in the right picture|
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|Figure 12: Pulsatile vascular compression of left main bronchus in a case of tetralogy of fallot with absent pulmonary valve and enlarged left pulmonary artery|
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|Figure 13: Tracheomalacia is confirmed when tracheal opening is seen to collapse (right picture) in the respiratory cycle|
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|Figure 14: Bronchomalacia. (a) Bronchus open in inspiration, (b) Bronchus closes in expiration. Red arrow shows the collapsed bronchus during expiration|
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|Figure 18: Caseous material seen partially blocking the bronchial opening in two patients|
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12], [Figure 13], [Figure 14], [Figure 15], [Figure 16], [Figure 17], [Figure 18]
[Table 1], [Table 2]