Sublingual microcirculatory shock and loss of haemodynamic coherence during subarachnoid anaesthesia

Dear Editor,
Optimization of tissue perfusion is one of the primary goals of peri­operative care and its adequacy is often assumed based on systemic measures, such as mean arterial pressure (MAP). However, microcirculatory alterations may occur even when global haemodynamic variables are within normal targets and are associated with the development of organ dysfunction. Indeed, perfusion-related complications are a main cause of morbidity and mortality in the surgical population, especially within the first thirty postoperative days [1, 2].
Although several studies have emerged in the last years providing important data that highlight the relationship between intraoperative hypotension and organ injury [3, 4], intraoperative microcirculatory endpoints and the impact of microcirculatory-guided therapeutic interventions have not yet been well defined [5]. In this report, we present a case of intra­operative loss of haemodynamic cohe­rence in a patient with normal systemic haemodynamics during subarachnoid anaesthesia.
A 51-year-old white woman with a body mass index of 33.3 kg m–2, American Society of Anesthesiologists Physical Status Classification II, and stable general condition was scheduled to undergo total knee arthroplasty under subarachnoid anaesthesia. Her medical history was remarkable for well-controlled hypothyroidism and chronic psychosis managed with L-thyroxine (112 μg per day), nebivolol hydrochloride (5 mg per day), trazodone (150 mg per day), olanzapine (2.5 mg per day), agomelatine (25 mg per day), and prazepam (10 mg per day). Physical cardiopulmonary examination before surgery was unremarkable. Preoperative electrocardiogram and laboratory blood tests were also unremarkable except for haemoglobin of 10.6 g dL^–1 and creatinine of 0.46 mg dL^–1. Preoperative calculated plasma volume status was 0.32.
Upon arrival at the operating room, she was awake with a Glasgow Coma Scale score of 15 and no neurological deficiencies. Standard monitoring was placed. The patient was haemodynamically stable with heart rate 89 beats min^–1, arterial blood pressure 126/82 mmHg, respiratory rate 14 min^–1, peripheral oxygen saturation 99% on room air, and body temperature 36.4°C. Two large-bore (17G) intravenous cannulae were inserted. She received 5 mL kg^–1 of a balanced crystalloid solution to compensate for preoperative fasting and vasodilation associated with anaesthesia...


View full text...