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372 P R I N C I P L E S A N D P R A C T I C E O F C R I T I C A L C A R E

Native lung
( compliance)

Graft lung
( compliance)

FIGURE 14.4 Mechanism of pulmonary dynamic hyperinflation: distribu-
tion of inspiratory gas.

Commonly, ventilatory settings and respiratory weaning
are guided by pH rather than CO 2 levels. A modest degree
of hypercarbia is anticipated postoperatively and resolves
over time. Given that low-volume ventilation has a posi-
tive impact on lung recovery and long-term outcomes
in patients with adult respiratory distress syndrome
(ARDS), 147 it has now been recommended that SLTx and
BSLTx recipients receive similar settings to prevent baro-
trauma while providing adequate ventilation. 142 In SLTx FIGURE 14.5 Chest X-ray of patient with left single lung transplant for
recipients, ventilation perfusion mismatches can also be COPD who has developed PDH.
improved by inhaled NO and by positioning patients
regularly with the allograft uppermost. To ventilator
Allograft dysfunction can develop in SLTx recipients with To ventilator
a remaining native COPD lung who are ventilated via a
single-lumen ETT, due to gas trapping in the over-
distensible native lung, a condition known as pulmonary
dynamic hyperinflation (PDH) (see Figure 14.4). Any
condition that lowers the compliance of the allograft can
lead to PDH in these patients. Nurses need to be aware Tracheal cuff
of the patients who can potentially develop PDH and
to remain hypervigilant, as early signs and opportunities
to stabilise patients’ haemodynamic and respiratory R.U.L. bronchus
status quickly can be easily missed. Initial presentation
of PDH is usually a set of ABGs showing inadequate
ventilation (hypercarbia and hypoxaemia). However, this
pattern of ABG values must not be responded to with R. main bronchus L. main bronchus
increases in respiratory rate, tidal volume or PEEP, as
these actions will exacerbate the degree of native lung
hyperinflation; rather, minute ventilation must be Bronchial cuff
reduced. 148 FIGURE 14.6 Correct positioning of double-lumen endotracheal tube for
pulmonary dynamic hyperinflation.
Other common presenting cues of PDH include a hae-
modynamic profile of cardiac tamponade, tracheal devia-
tion, obvious hyperinflation of the native lung with or
without mediastinal shift on chest X-ray, decreased air physician is required to administer an anaesthetic, insert
entry to the allograft on auscultation and pneumothorax. a dual-lumen ETT, check the position of each lumen’s
The early stages of PDH in a patient with a left SLTx for position and cuff with an intubating bronchoscope.
COPD can be seen on the chest X-ray in Figure 14.5. Secure placement of the tube is paramount, to avoid
Immediate management of the condition requires slight movement of the position and consequent dis-
attempts to minimise hyperinflation with altered ventila- placement of correct cuff placement (see Figure 14.6 for
tory settings and bronchodilators. If this fails, a skilled correct positioning of a dual-lumen ETT).