An uncuffed endotracheal tube (ETT) is rarely the standard of care for the pediatric patient. Depending on the circumstance, it can provide unique challenges to ventilation. When that uncuffed ETT is also too small for your patient, it now becomes a safety issue with respect to appropriate ventilation. Oftentimes this scenario is played out by referring staff before the transport team even arrives at the bedside. The team can find itself relegated to what worked best after several intubation attempts, and this choice can often be suboptimal for safely moving and ventilating a child with any consistency from a ventilation standpoint. This was recently the case for one of our teams. In this discussion, we provide the background and our decisions with the disclaimer that while we recognize the established standard of care, there are times that what is best for the patient might not follow that standard.
Consider the following case….
Our team was dispatched to a referring Pediatric Intensive Care Unit (PICU) for a 4-month-old female with an extensive past medical history significant for prematurity (33 3/7 weeks), Trisomy 21, and complete Atrio-Ventricular Septal Defect (AVSD) who is now admitted with aspiration pneumonia and worsening respiratory distress. Per nursing report, the patient presented a day earlier with a room air oxygen saturation (SpO2) of 50%. On admission, her chest x-ray (CXR) exhibited a ground-glass appearance with infiltrates in the right lung. A repeat CXR on the day of transport showed worsening ground-glass appearance and infiltrates throughout both lung fields.
The infant was tachypneic in the 80-bpm range with head bobbing, grunting, and retracting, prompting an increase in her oxygen support to high flow nasal cannula at 8LPM and 100% FiO2. She was experiencing SpO2’s around 90-92%, with precipitous drops to low 80’s with stimulation or stress. Understanding that transport via helicopter has some inherent stressors for the patient, the crew felt that first securing her airway and then sedating her for transport was safest and most appropriate.
Upon arrival to the referring unit, preparations for intubation were underway by the referring PICU team. The transport team immediately began preparing the monitor and ventilator as weather was moving in and an expeditious turn-around time was requested by the pilot. The team waited outside the patient’s room per request of the PICU staff. 25 minutes had passed when the team was brought to the bedside by the PICU fellow who shared the following events:
- 1st intubation attempt – #3.5 cuffed ETT. Grade I view using a GlideScope® Core™. Unable to pass the tube beyond the tracheal opening.
- 2nd intubation attempt – #3.0 cuffed ETT. Grade I view using GlideScope® Core™. Unable to pass the tube beyond the tracheal opening.
- 3rd intubation attempt- #2.5 uncuffed ETT. Grade I view using GlideScope® Core™. Tube passes easily, however large leak present with minimal chest rise with Bag/ETT ventilation.
- 4th intubation attempt – #3.0 uncuffed ETT. Grade I view using GlideScope® Core™. Tube passes easily, leak persists but can be managed with troubleshooting techniques such as chin-to-chest position that closed patient’s mouth.
The infant was being ventilated with a manual resuscitation device through the ETT (BVETT). She had bilateral chest rise and SpO2 of 100%. She was placed on our Hamilton T1 ventilator with the following settings: AC/PC, f-36 bpm, PEEP +6 cmH2O, Delta P 24 cmH2O , PIP 30 cmH2O generating a 46-50 ml tidal volume, inspiratory time (Ti) 0.6 seconds, and 100% FiO2. Initial waveform capnography (EtCO2) reading was 86 mmHg. Close monitoring of EtCO2 showed a gradual decline on these settings. A CXR was ordered to confirm tube placement prior to departure.
As the infant was being lifted off of the X-ray plate, her leak worsened, the ventilator began alarming “Low Minute Ventilation”, her SpO2 dropped to 88% and her EtCO2 precipitously rose to 78mmHg (it had fallen to 40mmHg after initiation of mechanical ventilation). BVETT ventilations were initiated with SpO2 quickly returning to 100% and EtCO2 slowly recovering. Bilateral chest rise was noted and ETT position was confirmed unchanged. The baby was moved to the transport stretcher and secured with manual ventilations ongoing. Just prior to departure, the Hamilton ventilator was again attempted however, the leak persisted (74% leak measured by ventilator), the ventilator alarmed, SpO2 began to drop, and EtCO2 began to rise to a dangerous level.
Now what do we do?????
A great deal of discussion ensued whether or not to change out the ETT for a third time prior to our departure. We asked ourselves the following questions as we decided how to proceed…
Q: Is this safe for the patient and crew?
A: While everyone at the bedside (referring MD, referring RN, referring RT, flight crew) agreed that this was not ideal, we all agreed that it was, in fact safe. We were able to handbag the patient for a good deal of time and during that time we were able to maintain SpO2’s of 99-100% and an EtCO2 of 35-42 mmHg. We observed bilateral equal chest rise and fall with minimal pressures (25-30 cmH2O measured with the manometer attached to the manual resuscitation device). We were able to generate a PEEP +6 cmH2O utilizing a PEEP valve. The patient was chemically sedated and paralyzed ensuring respiratory synchrony.
Q: Are we able to adequately ventilate/oxygenate with the current ETT?
A: This was an easy “yes” given vital signs and the observations stated above with hand bagging.
Q: Do we have the resources to complete the transport while hand bagging the patient?
A: The use of a ventilator during transport provides consistent ventilation to an intubated patient. Additionally, there are alarm parameters that alert clinicians when changes occur with ventilator parameters. Since we would not be using a ventilator, we agreed that one of us would be designated to the airway and that job would be to solely manage ventilation/oxygenation. It was determined that this small patient would likely not need extensive interventions during the transport (PRN sedation was determined to be only foreseeable intervention needed).
Q: Is the patient a known difficult airway?
A: Per the referring pediatric cardiologist, there was a “difficult airway” diagnosis at one time that was evaluated prior to her open-heart surgery that is now being called “resolved”. Given this diagnosis and the difficulty in passing an ETT on this admission, the flight crew felt that there was some validity to the difficult airway diagnosis and attempting to change out the ETT could prove to be difficult again.
Q: Can the patient be effectively bag/mask ventilated in the event this tube no longer allowed for adequate ventilation/oxygenation?
A: Both flight nurses had observed bag/mask ventilations of the baby prior to the 3rd and 4th intubation attempt. In both instances, the baby was easily ventilated/oxygenated using a manual resuscitation device (BVM). The resuscitation mask utilized was taken from the bed and taped above the patient’s head on the transport stretcher so that it would be easily accessible in the event of ETT dislodgement.
Q: Is there a potential for airway swelling due to the diagnosis? RSV, epiglottitis, COVID, croup, etc. may make intubation efforts difficult?
A: In this case no. While a COVID-19 screen was not done on the baby, her CXR (ground glass with infiltrates) and respiratory assessment (pursed lip breathing, head bobbing, retractions, grunting, tachypnea, low SpO2, and high oxygen requirements) fit with the aspiration pneumonia diagnosis.
Q: Are there potentially harmful consequences to the patient from an additional intubation attempt?
A: While intubation is a life-saving procedure, it does not come without potential for harm. Injury to the trachea such as rupture or tracheomalacia can occur with excessive intubation attempts, traumatic intubations, or aggressive and frequent suctioning (Walsh, 2019). Multiple attempts can lead to airway damage/swelling making efforts to change out the ETT more difficult. This baby had been intubated at birth, intubated for her AVSD surgical repair, and had 4 intubation attempts on this day. It was decided that another intubation attempt could cause harm to the patient’s airway.
Q: Can we expect a lengthy transport time?
A: Tolerance of an air leak is inversely proportionate to flight times. In this instance, we had a door-to-door time of less than one hour increasing our confidence that we could continue to ventilate/oxygenate this baby until we reached the accepting facility.
Q: Do we have time to perform an intubation?
A: While weather is never the ultimate deciding factor for a situation like this, it is involved in decision making. The pilot had requested as expeditious of a turn-around as we could give him due to the potential for pop-up thunderstorms. If we took the time to do the intubation and deal with any potential problems we might encounter (such as those the referring PICU MD did), we may end up having to transport via ground ambulance leading to longer out-of-hospital times, more moving increasing the risk of tube dislodgement, and potentially more agitation.
So, after careful discussion and evaluation of the situation, we decided collectively to transport the baby with the #3.0 uncuffed ETT and utilize positioning and ventilation techniques to aid in ventilation/oxygenation.
Positioning Techniques Used to Decrease a Leak in an Uncuffed ETT
- Flexion of the head (chin to chest). Remember that this will bring your ETT up some so use caution with an ETT that is already high as this maneuver may lead to inadvertent extubation.
- Extension of the head. Try a roll under the patient’s shoulders or extension of the neck. Use caution in low ETT’s as this maneuver may lead to inadvertent movement of the ETT into the right mainstem bronchi.
- Make every effort to avoid bending the ETT back and securing the vent tubing on the side of the head/face that the ETT is taped on. This position could worsen the air leak by pulling on the tracheal opening allowing more air to escape. Additionally, ETT’s are plastic and body heat creates a permanent “curve” in the tube. Self-extubation can occur with only a small movement of the head away from the ETT if it is not secured properly.
***ALWAYS draw ETT across the mouth and secure vent tubing on the opposite side of ETT tape***
Securing of the ETT on the same side of the head as the tube is taped may result in extubation if the patient suddenly moves their head to the side. This could also worsen an air leak because the ETT is pulled thus stretching the tracheal opening allowing air to escape.
Moving the ETT across the mouth will prevent inadvertent self-extubations by the patient moving their head and may help minimize airway leaks.
Reduce flow rate
Regardless of whether you use a ventilator or a resuscitation bag to ventilate/oxygenate your patient, reducing the flow rate of delivered gas may help overcome the leak and improve gas distribution. At low flow rates, the stream lines of air flow are parallel to the sides of the tube. This is known as laminar flow (Fig. A BELOW). As the flow rate is increased, unsteadiness develops, especially at branches (Fig. C BELOW). Here, separation of the stream lines from the wall may occur. At still higher flow rates, complete disorganization of the stream lines is seen (Fig. B BELOW); this is turbulence (Walsh, 2019).
The faster you deliver a breath, whether this is with a ventilator or a resuscitation bag, the more likely you are to disrupt laminar flow and increase turbulence. Turbulent air does not follow a specified pattern of distribution but will likely follow to the path of least resistance. In an uncuffed ETT that is too small for the patient, this path of least resistance will likely be out the mouth and nose resulting in an increased leak and less gas distribution.
Decreasing flow can be accomplished by doing any one of the following:
- Use longer inspiratory times (Ti). This may require you to increase pressures or rates to deliver an adequate minute ventilation.
- Turn down the flow on your resuscitation bag.
- Decrease the bias flow on your ventilator
Take Home Points
- While mechanical ventilation during transport is the standard of care, what is best and safest for the patient should always take precedent. Make your decisions based upon this and weigh the risk vs. benefit for THIS transport.
- Understand what can affect the position of a correctly placed ETT and take steps to mitigate excessive movement BEFORE initiating transport.
- If you understand how gas moves through the conducting and terminal airways, it is easier to understand how to control the movement and travel of that gas in order to optimize ventilation.
- As with any intervention, closely monitor your vital signs (specifically EtCO2 and SpO2) and patient for their response.
References
Miller, K. A., & Nagler, J. (2019). Advances in emergent airway management in pediatrics. Emergency Medicine Clinics, 37(3), 473-491.
Walsh, B.K. (2019). Neonatal and pediatric respiratory care. (5th Ed.). St. Louis, MO: Elsevier
West, J.B. & Luks, A.M. (2016). West’s respiratory physiology: The essentials. (10th Ed.). Philadelphia, PA: Lippincott Williams & Wilkins.