Regarding neurosurgical characteristics, stable awake status and recovery of neural function are required as soon as possible to facilitate early neurological examination and improve the neurological outcome. Studies show that overall complications after neurosurgery are relatively high[7–11]. In our research we analyzed data of 1586 adult patients over a period of 1 year to obtain a better understanding of postoperative complications in neurosurgery.
The main finding of our study is that the most frequent complication was hypertension, followed by hypoxemia and airway obstruction. The thresholds used in clinical hypertension have included either SBP > 160 mmHg, DBP > 90 mmHg, MAP > 110 mmHg, or a relative change from baseline (an increase in SBP or DBP of ≥ 20%). In specific cases such as ruptured aneurysm, patients may already have hypertension before surgery. For this reason we used the increase in SBP or DBP of ≥ 20% as the threshold to treat hypertension.
For neurological patients, hypertension in the perioperative and postoperative period may increase intracranial pressure and cause bleeding at the surgical site, intracranial hemorrhage, or cerebral ischemia, resulting in poor outcomes that include prolonged hospital stay, brain dysfunction, and increased mortality, especially in the first 24 hours[17–20]. One study found that post-craniotomy intracranial hematoma was associated with intraoperative and postoperative hypertension. In our study the incidence of hypertension was 23% in cranial cases and 16% in spinal cases, similar to the findings from a study by Rolston et al. in which cranial cases were more likely to have complications than spinal cases. This may be explained by the nature of disease requiring cranial neurosurgery being very different from that requiring spine surgery, whereby the former is often much more liable to operative complications. In addition, acute physiological changes during anesthesia recovery (such as increased cerebral blood flow and intracranial pressure) can add to the severity of intracranial complications.
In our study, we found trigeminal neuralgia is the most common surgery type leading to hypertension. It may due to that the patients who suffer from trigeminal neuralgia have a high frequent of a concomitant hypertension, which is called neurogenic essential hypertension[22, 23]. Besides, the severe pain of this disease may stimulate the sympathetic system, thus increasing the blood pressure.
Not surprisingly, aneurysm patients are second most frequently affected by hypertension. For patients with aneurysmal subarachnoid hemorrhage, preceding hypertension is an independent risk factor for poor outcome and cerebral infarction. Research has also indicated that normalization of blood pressure will significantly reduce the incidence of aneurysm rupture, while partial normalization of blood pressure will lead to a trend of reduced rupture rate. Overall, therefore, there appears to be a dose-dependent relationship between blood pressure reduction and prevention of aneurysmal rupture.
It should be noted that some factors such as pain, anxiety, ureter discomfort, hypothermia, and hypoxia are associated with postoperative hypertension and should be excluded before administering antihypertensive drugs. In our study, postoperative moderate to severe pain occurred in 51 of the patients (3.22%) in the PACU, almost half of whom (45.1%) had hypertension. Research shows that the MAP is higher in patients with severe postoperative pain than in those with no or mild pain. In proportion to the severity of the stimulus, the spinal reflexes recruited by increasing pain may cause activation of the sympathetic nervous system, which increases peripheral resistance.
The general incidence of postoperative nausea and vomiting (PONV) is about 30–50%, and up to 80% in high-risk groups without antiemetic prophylaxis after surgery[28–31]. Owing to changes in intracranial pressure, cerebral intravascular pressure, hemostasis, and cerebral perfusion, the incidence of PONV in craniotomy surgery is higher. Since it is a frequently occurring postoperative complication in the neurosurgery patient population, a variety of antiemetic agents is used to lower the incidence of PONV, such as 5-HT3 receptor antagonists, dexamethasone, metoclopramide, and the neurokinin-1 receptor blocker aprepitant[33, 34]. In our study, PONV problems occurred in 1.77% of patients, For which we use tropisetron, a serotonin antagonist used in the prevention of chemotherapy-induced nausea and vomiting.
In our study, the risk factors of hypertension such as hypertensive comorbidities, sex, advanced age, and the duration of general anesthesia are traditional predictors. Since research on the risk factors for postoperative hypertension remain inadequate, further investigation is warranted.
This study has some limitations. First and most importantly, it is an observational study and therefore can only address association but not causality. Second, because most emergence operations went to ICU after surgery, so we only included elective neurosurgery, while most hypertensive cerebral hemorrhage patients, who make up a sizable proportion of the general hypertensive population, undergo surgery in the emergency operating room.