Intense Intraoperative Thirst: A Neglected Concern during Awake Craniotomy Surgeries

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To JNA Readers:
The advantages of optimal resection over the eloquent cortex, constant communication with patients, reduced hospital stay, less resource utilization, and higher patient satisfaction1,2 have enhanced the popularity of the awake craniotomy technique for tumor excision, epilepsy, and deep-brain stimulation surgeries. Commonly, these cases are conducted under scalp block (with local anesthetics) along with conscious sedation using drugs such as opioids (fentanyl, remifentanil), midazolam, propofol, or dexmedetomidine. The application of these unconventional techniques has led to the emergence of newer clinical dilemmas, which hitherto were not observed under general anesthesia as consciously sedated patients are able to verbalize.
We wish to report our experiences with 2 patients who were undergoing awake craniotomies under bilateral scalp blocks and intravenous dexmedetomidine sedation. Midway through the surgery, both the patients started complaining of severe dryness of mouth and demanded drinking water. Severe thirst caused significant restlessness and anxiety in these patients. Repeated verbal explanations and assurances failed to pacify these patients and the surgery had to be interrupted repeatedly. The distress made the patients agitated and raised apprehensions of them hurting themselves, as their heads were fixed with pins over frames. Ultimately, we had to administer 2 small aliquots (10 mL each) of water orally to placate them and allow the completion of surgery.
Various factors make these patients prone to intraoperative dehydration. Mandatory fasting before surgery is one of the main reasons causing dryness of the mouth and the throat. The American Society of Anesthesiologists recommends fasting from the intake of clear liquids for at least 2 hours before elective procedures requiring general/regional anesthesia or sedation/analgesia (ie, monitored anesthesia care).3 Avoiding unnecessary prolongation of the fasting period and allowing clear fluids till the stipulated period ensures adequate hydration perioperatively. Diuretics (mannitol) used to reduce the brain volume can potentiate dehydration. High ambient temperatures and low humidity caused by overhead lights in operation theaters enhance insensible losses from mucosal surfaces. Thus, stringent regulation of operation theaters temperatures and humidity should be ensured, especially in tropical climates, to provide optimum comfort and prevent moisture loss. Oxygen supplementation through a face mask or nasal prongs should utilize adequately humidified oxygen to prevent drying of the oral mucosa. Anticholinergic drugs such as glycopyrrolate have antisialogogue effects and can cause appreciable dry mouth. Unless absolutely indicated, they should be avoided during awake surgeries. Dexmedetomidine, which is extensively used during conscious sedation, includes dry mouth in its side-effect profile.4Although uncommon, fentanyl administration may cause xerostomia.5
The success of awake craniotomy largely depends on patients' cooperation. Preventing distress and ensuring optimum intraoperative comfort contributes immensely to the smooth conduct of this novel technique. With the widespread use of conscious sedation for awake craniotomies, underrated problems such as intraoperative thirst are surfacing. These scenarios should be anticipated beforehand and should be explained sympathetically during preoperative counseling. The above-mentioned factors, which can aggravate intraoperative thirst and dryness, should be modified suitably according to the existing local practices. In addition, as continuous intraprocedural verbal communications can further aggravate dry mouth, it should be limited to the absolutely essential clinical queries.

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