Opioid versus non-opioid analgesia for spine surgery: a systematic review and meta-analysis of randomized controlled trials.

PURPOSE: Opioids are the primary analgesics used in patients undergoing spine surgery. Postoperative pain is common despite their liberal use and so are opioid-associated side effects. Non-opioid analgesics are gaining popularity as alternative to opioids in spine surgery. METHODS: This systematic review evaluated current evidence regarding opioid and non-opioid intraoperative analgesia and their influence on immediate postoperative pain and adverse events in spine surgery. RESULTS: A total of 10,459 records were obtained by searching Medline, EMBASE and Web of Science databases and six randomized controlled trials were included. Differences in postoperative pain scores between opioid and non-opioid groups were not significant at 1 h: 4 studies, mean difference (MD) = 0.65 units, 95% confidence intervals (CI) [-0.12 to 1.41], p = 0.10, but favored non-opioid at 24 h after surgery: 3 studies, MD = 0.75 units, 95%CI [0.03 to 1.46], p = 0.04. The time for first postoperative analgesic requirement was shorter (MD = -45.06 min, 95%CI [-72.50 to -17.62], p = 0.001), and morphine consumption during first 24 h after surgery was higher in opioid compared to non-opioid group (MD = 4.54 mg, 95%CI [3.26 to 5.82], p < 0.00001). Adverse effects of postoperative nausea and vomiting (Relative risk (RR) = 2.15, 95%CI [1.37 to 3.38], p = 0.0009) and shivering (RR = 2.52, 95%CI [1.08 to 5.89], p = 0.03) were higher and bradycardia was lower (RR = 0.35, 95%CI [0.17 to 0.71], p = 0.004) with opioid analgesia. CONCLUSION: The certainty of evidence on GRADE assessment is low for studied outcomes. Available evidence supports intraoperative non-opioid analgesia for overall postoperative pain outcomes in spine surgery. More research is needed to find the best drug combination and dosing regimen. Prospero Registration: CRD42020209042.

Regional Cerebral Oxygen Saturation Changes After Decompressive Craniectomy for Malignant Cerebral Venous Thrombosis: A Prospective Cohort Study.

BACKGROUND: Decompressive craniectomy (DC) is a life-saving intervention for malignant cerebral venous thrombosis (CVT). Earlier studies have shown increase in cerebral oxygenation after DC in traumatic brain injury but similar studies are lacking in CVT. We hypothesized that regional cerebral (tissue) oxygen saturation (rSO2) on the side of CVT is lower than the contralateral side and improves after DC. MATERIALS AND METHODS: In this prospective cohort study, rSO2 was monitored using near-infrared spectroscopy technique, before and after DC on both cerebral hemispheres. Data regarding factors likely to affect rSO2 such as systolic blood pressure, partial pressure of oxygen and carbon dioxide in blood (PaO2 and PaCO2), and hemoglobin were simultaneously collected. The primary outcome measure was pre-post change in rSO2 on the ipsilateral cerebral hemisphere. The secondary outcomes were in-hospital mortality and duration of postoperative hospital stay. RESULTS: Seventeen patients underwent DC during the 6-month study period. Their mean age was 39.2±12.4 years. The pre-post DC change in rSO2 on the hemisphere with CVT was significant (mean difference=3.6%; 95% confidence interval, 1.5-5.7; P=0.002). One patient died in the hospital. There was no difference in the duration of postoperative hospital stay (10 d [range, 6 to 21 d] vs. 14 d [range, 1 to 30 d], P=0.92) between patients with preoperative ipsilateral rSO2 <60% and >60%. There was no correlation between PaO2, PaCO2, systolic blood pressure, and hemoglobin with rSO2. CONCLUSIONS: Patients with malignant CVT had a lower rSO2 on ipsilateral side of the lesion, which improved significantly after DC. Preoperative rSO2 was not correlated with the duration of hospital stay.

Cerebral vasospasm: current understanding.

PURPOSE OF REVIEW: With recent research trying to explore the pathophysiologic mechanisms behind vasospasm, newer pharmacological and nonpharmacological treatments are being targeted at various pathways involved. This review is aimed at understanding the mechanisms and current and future therapies available to treat vasospasm. RECENT FINDINGS: Computed tomography perfusion is a useful alternative tool to digital subtraction angiography to diagnose vasospasm. Various biomarkers have been tried to predict the onset of vasospasm but none seems to be helpful. Transcranial Doppler still remains a useful tool at the bedside to screen and follow up patients with vasospasm. Hypertension rather than hypervolemia and hemodilution in 'Triple-H' therapy has been found to be helpful in reversing the vasospasm. Hyperdynamic therapy in addition to hypertension has shown promising effects. Endovascular approaches with balloon angioplasty and intra-arterial nimodipine, nicardipine, and milrinone have shown consistent benefits. Endothelin receptor antagonists though relieved vasospasm, did not show any benefit on functional outcome. SUMMARY: Endovascular therapy has shown consistent benefit in relieving vasospasm. An aggressive combination therapy through various routes seems to be the most useful approach to reduce the complications of vasospasm.

Changing trends in monitoring brain ischemia: from intracranial pressure to cerebral oximetry.

PURPOSE OF REVIEW: Cerebral ischemia forms the pathophysiological basis of several acute neurological conditions. Successful management of these conditions depends on early and accurate identification of ischemia and prompt treatment. Several techniques of assessing ischemia have evolved over decades. But their importance in the management of neurological patients remains ambiguous. RECENT FINDINGS: Current trends in monitoring cerebral ischemia follow two pathways: (1) Indirect methods of assessing global and regional cerebral perfusion [intracranial pressure/cerebral perfusion pressure (ICP/CPP), transcranial Doppler]; and (2) Assessment of adequacy of cerebral blood flow (CBF) at tissue level by monitoring global or regional oxygenation and metabolism (SjvO2, rSO2, PbtO2, microdialysis).Traditional approach to ICP/CPP monitoring has changed to more complex analysis of the ICP waveform to derive variables related to cerebral perfusion and vascular reactivity. Noninvasive techniques of cerebral perfusion pressure assessment are under investigation. Newer methods are being explored to derive indices of CBF autoregulation from various modalities of cerebral monitoring. Direct brain tissue oxygen tension monitoring and microdialysis facilitate regional monitoring of oxidative metabolism. However, there seems to be some complexity in interpreting the results from these monitors. SUMMARY: A wide range of options are available for monitoring adequacy of regional and global CBF. But no single monitor per se fulfils the requirements of all clinical situations. Impact of these monitors on clinical outcomes is equivocal. Also, at present, many of these monitors are invasive and not cost-effective.

Pulmonary function after surgery for congenital atlantoaxial dislocation: a comparison with surgery for compressive cervical myelopathy and craniotomy.

Deterioration of pulmonary function after surgery for congenital atlantoaxial dislocation (AAD) has been documented in a few studies. We proposed that this deterioration in AAD is much higher than what can be expected after a surgical procedure under general anesthesia or what occurs after any surgery on the cervical spine. To test this hypothesis, we recorded forced vital capacity (FVC), forced expiratory ratio (FEV 1.0), forced expiratory flow (FEF 25%-75%) and muscle power in the extremities in 25 patients undergoing surgical correction of AAD (AAD group), 29 patients undergoing surgery for compressive cervical spine lesions (cervical spine group) and 20 patients undergoing craniotomy for an intracranial lesion (craniotomy group). The observations were made before surgery and on postoperative days 1 and 7. The demographic characters were comparable among the 3 groups. All patients underwent an uneventful surgery and their trachea was extubated in the operating room. There was no decrease in the muscle power in the postoperative period in any of the groups. A significant decrease in FVC (expressed as percentage of the predicted value) was seen postoperatively in all the 3 groups. The reduction of FVC was significantly different among the groups, with the AAD group having the lowest values (P<0.001). The FVC values in the AAD group were 74.6+/-19.6%, 49.6+/-17.7%, 64.0+/-20.8% at baseline, on postoperative days 1 and 7, respectively (P<0.001). Postoperative change in forced expiratory ratio was also significantly different among the groups (P=0.03). A significant difference was found between the AAD and cervical spine group (89.8+/-8.3%, 88.2+/-17.6%, 89.3+/-9.8% in the AAD group and 95.5+/-20.5%, 78.4+/-13.4%, 72.7+/-19.1% in the cervical spine group at baseline and on postoperative days 1 and 7, respectively, P<0.05). FEF 25%-75% changes were also significantly different among the groups (P<0.001). The decrease in the AAD and cervical spine groups was significantly higher than that in the craniotomy group (P<0.001). In conclusion, during the first week after surgery, deterioration of pulmonary function in the AAD group is significantly different from that seen in patients undergoing surgery for compressive cervical lesions or craniotomy for a cerebral lesion. The data imply the need for special attention to respiratory function in patients operated for AAD in the postoperative period.

Cerebrovascular reactivity to carbon dioxide in the normal and abnormal cerebral hemispheres under anesthesia in patients with frontotemporal gliomas.

Cerebral pathology may alter the cerebrovascular reactivity to carbon dioxide (CO2). In the present study, in patients with brain tumors, we examined the cerebral vascular reactivity to CO2 in the cerebral hemispheres with and without tumors under intravenous and inhalational anesthesia. Twenty-nine patients undergoing craniotomy for frontotemporal gliomas were randomized to receive intravenous anesthesia with propofol or inhalational anesthesia with isoflurane. Cerebral blood flow velocity in the middle cerebral artery (VMCA) and pulsatality index were measured under normocapnia and hypocapnia in the normal cerebral hemisphere and the hemisphere with tumor. Hypocapnia significantly decreased the VMCA in both the cerebral hemispheres under both the anesthetic techniques (P < 0.006). The percentage change in VMCA was similar between the hemispheres with and without tumor both under isoflurane (3.45 +/- 4.11% on the normal side and 2.91 +/- 2.40% on the tumor side; mean difference 0.54 +/- 1.31%; 95% CI -2.18 to +3.27) and propofol anesthesia (2.32 +/- 2.64% on the normal side and 1.69 +/- 4.04% on the tumor side; mean difference 0.63 +/- 1.2%; 95% CI -1.83 to +3.10). The changes in pulsatality index also were not significantly different between the hemispheres. In conclusion, cerebrovascular response to hypocapnia is similar between the normal and the abnormal cerebral hemispheres both under intravenous and inhalational anesthesia.

Spontaneous intraoperative hypothermia and cerebral protection in aneurysmal subarachnoid hemorrhage.

BACKGROUND: In patients with aneurysmal subarachnoid hemorrhage (SAH), a trend towards cerebral protection has been demonstrated with intraoperative mild hypothermia. Mild to moderate spontaneous hypothermia occurs intraoperatively if no active measures are taken to warm the patient. The present study investigated the cerebral protective role of such spontaneous intraoperative hypothermia in patients with aneurysmal SAH. METHODS: In 50 patients undergoing surgery for aneurysmal subarachnoid hemorrhage, nasopharyngeal temperatures were monitored from the time of endotracheal intubation till the end of surgery. The patients were observed for any neurological deterioration during the first 24 h postoperatively. The temperatures of the deteriorated and nondeteriorated patients, at different stages during surgery, were compared. RESULTS: Ten out of the 50 patients showed neurological deterioration within the first 24 h after surgery. The nondeteriorated patients had significantly lower nasopharyngeal temperatures compared to the deteriorated group at the time of dural opening, temporary vessel occlusion (TVO), dural closure and the end of surgery (p < or = 0.05). They also had a significantly lower temperature for 2 h starting from the time of temporary vessel occlusion (p < or = 0.05). When the patients were divided into hypothermic (< 34.5 degrees C) and normothermic groups (> 34.5 degrees C) on the basis of their nasopharyngeal temperature at the time of TVO, the normothermic group tended to have a higher incidence of postoperative neurological deterioration (p = 0.07). When the aneurysms were classified according to their anatomical location, a significant intraoperative temperature difference between the deteriorated and nondeteriorated groups was evident only in patients with anterior communicating artery aneurysms (p < or = 0.02) and not others. Infective complications were more frequent in hypothermic patients (p = 0.02). CONCLUSIONS: The findings of the current study suggest that mild spontaneous intraoperative hypothermia offers cerebral protection in patients undergoing surgery for aneurysmal subarachnoid hemorrhage. This protective role of seems to be related to the anatomical location of the aneurysm.