Efficient handling of cardiac patients in cardiac surgeries is not an easy task. Patients
are labile and more liable than others to hemodynamic changes in response to anaesthetic
drugs and unfortunately, these changes are not well tolerated. (Choudhury A et al., 2017)
Any Hemodynamic change can have a great impact on the oxygen delivery - demand balance
and lead to more damage. Every step is critical, but induction is the most challenging
representing the peak of the dynamicity. Any change could happen, either tachycardia,
hypertension, or arrhythmia in response to intubation or hypotension after induction or
during period of minimal stimulus. (Soleimani A et al., 2017)
Although the concept of opioid based anaesthesia was the gold standard in cardiac
surgeries for decades as opioids lack the negative inotropic effects, their usage was
shifted from the mega doses of long acting opioids to titrating doses of short acting
ones as fentanyl that became the primary in use.(Grant MC et al., 2023) Trying to control
stress response to intubation by higher doses of opioids increase the liability for post
induction hypotension which occurs in nearly one fourth to one third of patients
receiving general anaesthesia. (Chen B et al., 2021)
The stress response to intubation could be inhibited by blocking the sensory pathway and
hence the reflex response. Targeting the superior laryngeal nerve (SLN) that innervate
the base of the tongue, epiglottis, piriform fossa, and vallecula together with trans
tracheal topical anaesthesia will reduce the stress response to intubation. Fortunately,
it's not essential to master anatomical landmarks and invasive techniques to block the
sensory pathway as gradual topical spraying of local anaesthesia over the airway mucosal
surfaces will lead to nearly equivalent effect in a simpler way. (Pignot G et al., 2022)
Lidocaine is one of the most commonly used local anaesthetics. It is generally safe and
available in multiple dosage forms (topical, I.V., nebulizer and spray) and
concentrations. It has been widely used for several indications in general anaesthesia
starting from just cough suppression and reduction of sore throat to modulation of the
stress response to intubation. (Mikawa K et al., 1997) Using lidocaine either topical or
by nebulizer is a well-established method to anesthetise airway and can be used safely in
cardiac surgeries. (Choudhury A et al., 2017) Also, lidocaine topical airway block showed
significant effect on reducing QT changes in patients undergoing cardiac surgeries if
applied before intubation. (Bilgi M et al.,2020)
Therefore, authors have hypothesised that air way block may help in reducing the doses of
opioids needed to control the stress response of intubation and hence to better
management of patient. This can be simply done by topical airway block with non-invasive
techniques that are both safe and applicable for practice.