Pediatric airway management and hypercarbia in a patient post lung transplant admitted for bronchial stent placement.
Frank van der Heusen MD, Neil Bennett MD
Department of Anesthesiology, University of Florida College of Medicine
Case Report: The patient is a six year old girl with a history of
bilateral lung transplant in for interstitial pneumonitis at age 3. She was
admitted this time because of increasing work of breathing, decreasing lung
function and multiple episodes of respiratory distress. She was found to
have right bronchomalacia and was therefore scheduled to undergo bronchial
stent placement by interventional radiology. Her past medical history
revealed bilateral lung transplant, multiple bronchoscopies, cataracts,
hypertension, vertebral fracture due to osteopenia, Gastrostomy tube, anemia
and transplant rejection. On physical examination the patient was awake and
cooperative anxious. Cosistent with delayed growth, her weight and height
were 14.2 kg and 99cm, respecively. Vital signs on supplemental oxygen
(2l/min by nasal cannula) were normal.
The patient was transported to interventional radiology for right sided
bronchial stent placement. During initial mask placement the patient was
fully awake and talking with an end-tidal (ET) CO2 of 70 torr. The initial
plan to place the bronchial stent under sedation failed, because the patient
did not tolerate the procedure and desaturated during airway manipulation by
the radiologist. Intermittend mask ventilation was required to maintain
oxygen saturations (SpO2) above 94%. A decision was made to let the patient
wake up and proceed under general endotracheal anesthesia. After
preoxygenation anesthetic induction was performed using mask induction with
sevoflurane and rocuronium for muscle relaxation. The patient was intubated
with a 5.5mm ID uncuffed endotracheal tube fixed at 16cm at the lip.
Ventilation was difficult and required high peak inspiratory pressures.
Fluoroscopy identified the tip of the endotracheal tube in the left mainstem
bronchus. Despite withdrawing the tube to 14cm at the lip, the patient
remained difficult to ventilate and was ventilated by hand with an FIO2 of
100%.
Post intubation the initial ET CO2 was 53 torr and ranged within 40-45 torr
with ventilation by hand. During radiologic manipulation through the ETT the
endtidal CO2 measurement was lost due to a significant leak via the uncuffed
tube as well as intermittent ventilation. The decision to extubate and
reintubate the patient was rejected because of possible dislodgement of the
bronchial stent. After stent placement and continued regular ventilation the
initial ET CO2 started out at 109 torr whilst saturation remaind stable at
100 %. We were able to hyperventilate and bring the ET CO2 down to 89 torr
before an arterial blood gas could be drawn which returned a ph of 6.94,
pCO2 140, pO2 303, HCO3 29, BE –5.5. The alveolar arterial pCO2 gradient was
arround 50 torr.
The patient had a prolonged awakening possibly secondary to CO2 narcosis and
was taken to the PICU intubated. The patient was extubated in the PICU on
POD #1 and was transferred to the floor the same day. The patient required
reintubation on POD #3 and despite a variety of ventilatory strategies the
pCO2 remained above 60 torr with an SpO2 of 100% on an FIO2 of 30%. The
patient required 3 more general anesthetics within the next 2 month during
which ET CO2’s ranged from 85-90 torr. Unfortunately the patient expiered 2
month after the initial case due to respiratory failure, acute renal failure
and CHF.
Discussion:
- should a pediatric airway be secured with a smaller cuffed rather than a
uncuffed endotracheal tube on a routine basis. Advantages and disadvantages
will be discussed.
- hypercarbia and anesthesia – causes, complications and implications.
