Discussion

Endoscopic sinonasal surgery is indispensable in managing a spectrum of conditions from intractable rhinosinusitis to complex neurosurgical pathology.^{Reference Dalziel, Stein, Round, Garside and Royle7} Originally, this procedure was performed under topical local anaesthesia but was typically limited to nasal polypectomy and septal surgery, leaving remaining nasal anatomy largely intact. Evolving surgical techniques permitted more extensive resection, necessitating general anaesthetic to achieve adequate airway protection, immobilise the surgical field and maximise patient comfort.^{Reference Lee, Kapur and Ramsden8} However, increasingly comorbid and ageing populations have more systemic risks of general anaesthesia such as myocardial infarction,^{Reference Devereaux, Xavier, Pogue, Guyatt, Sigamani and Garutti9} venous thromboembolism,^{Reference Pannucci, Bailey, Dreszer, Fisher Wachtman, Zumsteg and Jaber10} aspiration^{Reference Cook, Woodall and Frerk11} and delirium.^{Reference Strom, Rasmussen and Sieber12} Local anaesthetic endoscopic sinus surgery may be of particular worth in patients with multiple cardiorespiratory comorbidities who are not fit for general anaesthetic and would otherwise be denied a surgical management option.

Endotracheal intubation itself is not without complication, ranging from a mild sore throat,^{Reference McHardy and Chung13} minor bleeding^{Reference Kalingarayar, Nandhakumar, Subramanian and Namboothiri14} and dental damage^{Reference Vogel, Stubinger, Kaufmann, Krastl and Filippi15} to laryngotracheal injury^{Reference Mota, de Cavalho and Brito16} and pneumothoraces.^{Reference Berg, Mafee, Campos and Applebaum17} Moreover, direct laryngeal stimulation during endotracheal intubation promotes a sympathetic response contributing to haemodynamic instability.^{Reference Stoelting18} Thus, the principle advantage of local anaesthetic techniques is in enabling substantive surgery to be performed without positive pressure ventilation or airway instrumentation as the patient maintains their own airway.^{Reference Jourdy and Kacker19}

The increasing prevalence of congestive cardiac failure^{Reference Roger20} and obesity^{Reference Davies21} has consequently increased rates of orthopnoea, rendering many patients physiologically unable to lie flat for procedures. Non-intubated patients can be positioned more upright; for example, the reverse Trendelenburg position provides 15° of head elevation.^{Reference Gan, Habib, Rajwani and Javer22,Reference Ghanem and Elmalt23} This increases venous drainage of the head and neck as blood pools in the lower extremities.^{Reference Knight and Mahajan24} Every 2.5 cm elevation above the level of the heart corresponds with a 2 mmHg reduction in mean arterial blood pressure.^{Reference Enderby25} Accordingly, more upright positioning together with the vasoconstrictive properties of local anaesthetic improves the surgical view.^{Reference Hathorn, Habib, Manji and Javer26} In turn, this reduces operative time by decreasing rod cleaning and suctioning.^{Reference Lee, Kapur and Ramsden8}

Adverse events in endonasal sinus surgery remain rare, but significant,^{Reference Krings, Kallogjeri, Wineland, Nepple, Piccirillo and Getz27} including cerebrospinal fluid leak, haemorrhage, orbital trauma, epiphora, optic nerve damage and meningitis.^{Reference Cumberworth, Sudderick and Mackay28} Under local anaesthesia, patients remain conscious throughout and are therefore able to signal any pain or discomfort, which theoretically minimises complications like orbital breach.^{Reference Lee, Kapur and Ramsden8,Reference Jourdy and Kacker19,Reference Fedok, Ferraro, Kingsley and Fornadley29} However, local anaesthetic endoscopic sinus surgery does not universally reduce the risk of intra-operative complications.^{Reference Hosemann and Draf30}

Vascular supply to the nasal cavities is extensive and anastomotic. Haemorrhage substantially disrupts visibility during endoscopic sinus surgery,^{Reference Milonski, Zielinska-Blizniewska, Golusinski, Urbaniak, Sobanski and Olszewski31} potentiating the risk of orbital, vascular or intracranial damage.^{Reference Tan and Poopalalingam32} Hypotension is deliberately achieved during general anaesthetic. The mean arterial blood pressure is lowered^{Reference Simpson33} in order to reduce intra-operative blood loss by up to 141 ml,^{Reference Elsharnouby and Elsharnouby34} thereby improving the surgical visual field.^{Reference Wormald, Athanasiadis, Rees and Robinson35} Although rare, intentional hypotension is not without consequence and theoretically may engender cerebral thrombosis, renal hypoperfusion and myocardial infarction.^{Reference Ghanem and Elmalt23,Reference Choi and Samman36,Reference Nishimura, Suzuki, Hatazawa, Nishimura, Shirane and Yasui37} The techniques outlined in this paper recommend the initial use of Lignospan (2 per cent lidocaine + 1:80 000 adrenaline). In addition to providing topical anaesthesia, this decongestant acts as a potent vasoconstrictor which aids mucosal decongestion and reduces haemorrhage, mitigating the hypotensive benefits seen in general anaesthesia.^{Reference Yang, Li, Jil, Wang, Sun and Wang38} Caution must be exercised as systemic absorption can result in hypotension,^{Reference Yang, Wang, Wang, Sun, Wang and Zuo39–Reference Phillips, Hutchinson, Bayly and Hollway41} hypertension,^{Reference Tanaka and Nishikawa42} tachycardia^{Reference Yang, Li, Jil, Wang, Sun and Wang38} and arrythmias^{Reference Thomas, Behbehani, Coyle and Denson43,Reference Sia, Sarro, Lepri and Bartoli44} depending on the anaesthetic agent selected. However, Cohen-Kerem et al.^{Reference Cohen-Kerem, Brown, Villasenor and Witterick45} demonstrated systemic absorption to be rare, and haemodynamic observations remained within normal range. Furthermore, although adrenaline theoretically reduces tissue perfusion,^{Reference Wilhelmi, Blackwell, Miller, Mancoll, Dardano and Tran46} the study by Hafner et al. of 10 000 patients undergoing ear and nasal surgery reported no cases of tissue necrosis.^{Reference Hafner, Rocken and Breuninger47} Procedures performed under local anaesthetic may induce fear, stress and pain, with consequent catecholamine release.^{Reference Guimaraes, Lopes Motta, Bergamaschi, Araújo, Andrade and Figueiró48} In turn, systemic stress hormones can cause hypertension and arrhythmias.^{Reference Godzieba, Smektała, Jedrzejewski and Sporniak-Tutak49,Reference Meyer50}

In addition to providing nasal anaesthesia, local vasoconstriction, mucosal decongestion and enhanced haemostasis, endonasal surgery performed under local anaesthetic permits early patient mobilisation and long-lasting post-operative analgesia.^{Reference Yang, Li, Jil, Wang, Sun and Wang38,Reference Caner, Olgun, Gultekin and Aydar51–Reference Lee, Yoo, Yon, Kim, Kim and Lee53} The initial discomfort associated with local anaesthetic blocks in the awake patient can be mitigated through slow infiltration and use of a fine 27-gauge needle.^{Reference Jourdy and Kacker19,Reference Metzinger, Bailey, Boyce and Lyons54} Procedures performed under local anaesthetic permit shorter total operative and recovery times^{Reference Jourdy and Kacker19,Reference Ghanem and Elmalt23} and help release anaesthetic capacity for other operating theatres.^{Reference Caner, Olgun, Gultekin and Aydar51} Fedok et al.^{Reference Fedok, Ferraro, Kingsley and Fornadley29} reported local anaesthetic procedures reduced total operative time by up to 22 per cent when compared with general anaesthetic. This was particularly noted for shorter, less extensive procedures (such as anterior ethmoid and maxillary sinus surgery), where the anaesthetic component forms a larger proportion of the total operative time. Although the absolute time saved was only 17.5 minutes, cumulative benefit by process of marginal gains may confer practical, clinical significance.

Overall, the substantial reduction in recovery time for local anaesthetic procedures proves more critical to patient flow and hospital efficiency than the slight reduction in operative duration. Patients recovering from general anaesthetic require higher-intensity, first-stage recovery which is more expensive and labour intensive. Faster recovery combined with reduced admission rate and lack of anaesthetist therefore reduces the procedure costs of local anaesthetic.^{Reference Jourdy and Kacker19,Reference Ghanem and Elmalt23} Patient preference is perhaps even more important; Caner et al. found 89 per cent of patients would choose to reselect future procedures to be performed under local anaesthetic.^{Reference Caner, Olgun, Gultekin and Aydar51} A dedicated time-and-motion study looking at local anaesthetic endoscopic sinus surgery may help quantify the relative cost-benefits over and above operating under sedation or general anaesthetic.

Endoscopic sinonasal surgery performed under local anaesthetic presents surgical challenges for analgesia, airway protection and immobilisation. Total nociceptive anaesthesia requires good knowledge of local anatomy, and some advocate the use of titrated sedation (such as midazolam, fentanyl, remifentanil or propofol infusion).^{Reference Lee, Kapur and Ramsden8,Reference Fedok, Ferraro, Kingsley and Fornadley29,Reference Buyukkocak, Ozcan, Daphan, Apan and Koc55,Reference Scamman, Klein and Choi56} When used, sedation does provide the advantage of retrograde amnesia.^{Reference Lee, Kapur and Ramsden8} However, caution should be advised as this experience can be disorientating and requires a dedicated sedation-trained healthcare professional. Airway evaluation must be scrupulous if sedation is planned, especially if an anaesthetist will not be present. Indeed, some endoscopic procedures performed under sedation have reported fatalities.^{Reference Thompson, Wright, Murray, Ritchie, Burton and Stonebridge57}

Other papers describing local anaesthetic techniques for endonasal surgery focus predominantly on topical mucosal anaesthesia, as opposed to regional nerve blockade, to achieve nasal anaesthesia. For example, Lee et al.^{Reference Lee, Kapur and Ramsden8} describe topical application of 25 per cent cocaine paste to progressively anaesthetise nasal mucosa. Although topical anaesthesia permits some endonasal procedures, including uncinectomy and exploration of sphenoid sinuses, it does not offer the formal regional block, as described in this paper. A variety of studies have assessed the role of local anaesthetic blocks with concomitant general anaesthesia.^{Reference Cho, Drover, Nekhendzy, Butwick, Collins and Hwang58–61} For example, Shamil et al.^{Reference Shamil, Rouhani, Basetti, Bast, Hopkins and Surda62} demonstrated a statistically significant reduction in post-operative pain following anterior ethmoidal and sphenopalatine ganglion blocks with 0.5 per cent Bupivicaine and 1:200 000 adrenaline. Crucially, all patients underwent general anaesthetic prior to endoscopic sinus surgery. Techniques outlined for the sphenopalatine ganglion block reflect our maxillary nerve block via the greater palatine foramen approach, whereas the anterior ethmoidal nerve block only blocks the anterior lateral nasal branch of the nerve. Although Jespersen et al. assessed the analgesic effects of a sphenopalatine ganglion block in patients receiving epidural blood patches, they successfully demonstrated that this technique can be plausibly performed under local anaesthetic.^{Reference Jespersen, Jaeger, Ægidius, Fabritius, Duch and Rye63} Sphenopalatine artery ligation can be performed under local anaesthetic using a maxillary nerve block via greater palatine foramen approach.^{Reference Jonas, Viani and Walsh64} Thus, for appropriately selected patient cohorts, the techniques outlined in this paper should provide sufficient analgesia to obviate the need for general anaesthesia or sedation as required by Lee et al.^{Reference Lee, Kapur and Ramsden8}

A combination of shrewd patient selection and good local anaesthetic technique should hopefully negate the need for sedation. Stoical patients may better tolerate local anaesthetic endoscopic sinus surgery if they have had previous experience of dental procedures or surgery performed under local anaesthetic. Tolerance of endoscopic nasal examination in an out-patient setting may indicate likelihood of successful local anaesthetic endoscopic sinus surgery. Patients should be co-operative, following precise instruction and remaining awake for the duration of the procedure. If applicable, pre-operative counselling should inform patients of the potential risk of conversion to general anaesthetic. However, Lee et al. found conversion was only required in 1 of 554 patients undergoing local anaesthetic endoscopic sinus surgery.