Effects of methylprednisolone on blood-brain barrier and cerebral inflammation in cardiac surgery-a randomized trial

BACKGROUND

Cognitive dysfunction is a frequent complication to open-heart surgery. Cerebral inflammation caused by blood-brain barrier (BBB) dysfunction due to a systemic inflammatory response is considered a possible etiology. The effects of the glucocorticoid, methylprednisolone, on cerebrospinal fluid (CSF) markers of BBB function, neuroinflammation, and brain injury in patients undergoing cardiac surgery with cardiopulmonary bypass were studied.

METHODS

In this prospective, randomized, blinded study, 30 patients scheduled for elective surgical aortic valve replacement were randomized to methylprednisolone 15 mg/kg (n = 15) or placebo (n = 15) as a bolus dose administered after induction of anesthesia. CSF and blood samples were obtained the day before and 24 h after surgery for assessment of systemic and brain inflammation (interleukin-6, interleukin-8, tumor necrosis factor-alpha), axonal injury (total-tau, neurofilament light chain protein), neuronal injury (neuron-specific enolase), astroglial injury (S-100B, glial fibrillary acidic protein), and the BBB integrity (CSF/serum albumin ratio).

RESULTS

In the control group, there was a 54-fold and 17-fold increase in serum interleukin-6 and interleukin-8, respectively. This systemic activation of the inflammatory cytokines was clearly attenuated by methylprednisolone (p < 0.001). The increase of the CSF levels of the astroglial markers was not affected. A postoperative BBB dysfunction was seen in both groups as the CSF/serum albumin ratio increased from 6.4 ± 8.0 to 8.0 in the placebo group (p < 0.01) and from 5.6 ± 2.3 to 7.2 in the methylprednisolone group (p < 0.01) with no difference between groups (p = 0.98). In the CSF, methylprednisolone attenuated the interleukin-6 release (p < 0.001), which could be explained by the fall in systemic interleukin-6, and the serum to CSF gradient of IL-6 seen both at baseline and after surgery. In the CSF, methylprednisolone enhanced the interleukin-8 release (p < 0.001) but did not affect postoperative changes in CSF levels of tumor necrosis factor alpha. Serum levels of S-100B and neuron-specific enolase increased in both groups with no difference between groups. CSF levels of total tau, neurofilament light chain protein, and neuron-specific enolase were not affected in any of the groups.

CONCLUSIONS

Preventive treatment with high-dose methylprednisolone attenuated the systemic inflammatory response to open-heart surgery with cardiopulmonary bypass, but did not prevent or attenuate the increase in BBB permeability or the neuroinflammatory response.

TRIAL REGISTRATION

Clinical Trials, Identifier: NCT01755338 , registered 24 December 2012.

Renal tubular injury during cardiopulmonary bypass as assessed by urinary release of N-acetyl-ß-D-glucosaminidase

BACKGROUND

Acute kidney injury (AKI) is a common complication with a major impact on morbidity and mortality after cardiac surgery with cardiopulmonary bypass (CPB). The aim of the present study was to perform a detailed analysis on the release of the tubular injury biomarker N-acetyl-b-D-glucosaminidase (NAG) during and early after CPB and to describe independent predictors of maximal tubular injury. We hypothesized that renal tubular injury occurs early after the onset of CPB.

METHODS

In this prospective observational study, we included 61 patients undergoing open cardiac surgery with an expected CPB duration exceeding 60 min. The urinary NAG levels were measured at 30 min intervals during CPB, as well as early (30 min) after CPB and post-operatively. Independent predictors of tubular injury were identified using an Interquantile multivariate regression model.

RESULTS

Already 30 min after the onset of CPB, NAG excretion was significantly increased (P < 0.001), followed by a sixfold peak increase after discontinuation of CPB (P < 0.001). In the multivariable regression model, CPB duration (P < 0.05) and the degree of rewarming during CPB (P < 0.05), were independent predictors of peak NAG excretion.

CONCLUSION

In cardiac surgery, a renal tubular cell injury is seen early after onset of CPB with a peak biomarker increase early after end of CPB. The magnitude of this tubular injury is independently related to CPB duration and the degree of rewarming. Efforts made to decrease the CPB duration and to avoid hypothermia and the need for rewarming may decrease the risk for tubular injury.

Epoprostenol for the treatment of increasing oxygenator pressure drop during cardiopulmonary bypass. A case report

A change of oxygenator during cardiopulmonary bypass is a technically high-risk procedure with potential for a serious adverse event for the patient. This case report describes a case of increased pressure drop and pre-oxygenator blood pressure during cardiopulmonary bypass successfully treated with pre-oxygenator-administered epoprostenol.

Pressure-dependent changes in haematocrit and plasma volume during anaesthesia, a randomised clinical trial

BACKGROUND

Induction of general anaesthesia has been shown to cause haemodilution and an increase in plasma volume. The aim of this study was to evaluate whether prevention of hypotension during anaesthesia induction could avoid haemodilution.

METHODS

Twenty-four cardiac surgery patients, 66 ± 10 years, were randomised to receive either norepinephrine in a dose needed to maintain mean arterial blood pressure (MAP) at pre-anaesthesia levels after induction or to a control group that received vasopressor if MAP decreased below 60 mmHg. No fluids were infused. Changes in plasma volume were calculated with standard formula: 100 × (Hct(pre)/Hct(post) - 1)/(1 - Hct(pre)). Arterial blood gas was analysed every 10 minutes and non-invasive continuous haemoglobin (SpHb) was continuously measured.

RESULTS

Pre-anaesthesia MAP was 98 ± 7 mmHg. Ten minutes after anaesthesia induction, the haematocrit decreased by 5.0 ± 2.5% in the control group compared with 1.2 ± 1.4% in the intervention group, which corresponds to increases in plasma volume by 310 ml and 85 ml respectively. MAP decreased to 69 ± 15 mmHg compared to 92 ± 10 mmHg in the intervention group. The difference maintained throughout the 70 min intervention period. The change in haemoglobin level measured by blood gas analysis could not be detected by SpHb measurement. The mean bias between the SpHb and blood gas haemoglobin was 15 g/l.

CONCLUSION

During anaesthesia induction, haematocrit decreases and plasma volume increases early and parallel to a decrease in blood pressure. This autotransfusion is blunted when blood pressure is maintained at pre-induction levels with norepinephrine.

Hypotension During Endovascular Treatment of Ischemic Stroke Is a Risk Factor for Poor Neurological Outcome

Background and Purpose—

In retrospective studies, patients receiving general anesthesia for endovascular treatment for acute ischemic stroke have worse neurological outcome compared with patients receiving conscious sedation. It has been suggested that this is caused by general anesthesia–associated hypotension. We investigated the effect of intraprocedural hypotension on neurological outcome.

Methods—

One hundred eight patients with acute ischemic stroke, who underwent endovascular treatment in general anesthesia between 2007 and 2012, were included. Analyzed predictors of neurological outcome were age, sex, comorbidities, baseline National Institutes of Health Stroke Scale, intraprocedural relative changes in mean arterial blood pressure from baseline, blood glucose, modified Thrombolysis in Cerebral Infarction score, and elapsed time from stroke to computed tomography, groin puncture, and recanalization/end of procedure.

Results—

A fall in mean arterial blood pressure of >40% was an independent predictor for poor neurological outcome ( P =0.032), as were higher admission National Institutes of Health Stroke Scale score ( P =0.008) and lack of recanalization ( P =0.003).

Conclusions—

Profound intraprocedural hypotension is an independent predictor for poor neurological outcome in patients with acute ischemic stroke undergoing endovascular therapy in general anesthesia.

The effects of sevoflurane on cerebral blood flow autoregulation and flow-metabolism coupling during cardiopulmonary bypass

BACKGROUND

previous studies on non-cardiac surgical patients have shown that cerebral pressure-flow autoregulation and cerebral flow-metabolism coupling are maintained with sevoflurane. The effects of sevoflurane on cerebral blood flow (CBF) autoregulation and flow-metabolism coupling during cardiopulmonary bypass (CPB) have not been studied previously.

METHODS

the effects of sevoflurane-induced burst suppression, monitored with electroencephalography (EEG), on cerebral blood flow velocity (CBFV), cerebral oxygen extraction (COE) and flow autoregulation, were studied in 16 patients undergoing cardiac surgery. The experimental procedure was performed during non-pulsatile CPB with mild hypothermia (34 degreesC) in fentanyl/droperidol-anesthetized patients. Middle cerebral artery transcranial Doppler flow velocity, right jugular vein bulb oxygen saturation and jugular venous pressure were measured continuously. Autoregulation was tested during changes in the mean arterial pressure (40-90 mmHg), induced by sodium nitroprusside and norepinephrine before (control), and during additional sevoflurane administration, in a dose that resulted in an EEG burst-suppression level of 4-6/min.

RESULTS

sevoflurane, at an inspired concentration of 3.36 ± 0.03%, induced a 17% decrease in CBFV (P<0.05) and a 22% decrease in COE (P<0.05) compared with the control. The slope of the positive relationship between CBFV and cerebral perfusion pressure was steeper with sevoflurane (p<0.01) compared with control measurements, as was the slope of the negative relationship between cpp and coe (p<0.01).

CONCLUSION

burst-suppression doses of sevoflurane exert an intrinsic cerebral vasodilatory effect, which impairs CBF autoregulation during mildly hypothermic CPB. Furthermore, during sevoflurane administration, CBF is in excess relative to oxygen demand, indicating a partial loss of the cerebral flow-metabolism coupling.

The Effects of Isoflurane-Induced Electroencephalographic Burst Suppression on Cerebral Blood Flow Velocity and Cerebral Oxygen Extraction During Cardiopulmonary Bypass

We investigated the effects of isoflurane-induced burst suppression, monitored with electroencephalography (EEG), on cerebral blood flow velocity (CBFV), cerebral oxygen extraction (COE), and autoregulation in 16 patients undergoing cardiac surgery. The experimental procedure was performed during nonpulsatile cardiopulmonary bypass (CPB) with mild hypothermia (32 degrees C) in fentanyl-anesthestized patients. Middle cerebral artery transcranial Doppler flow velocity, right jugular vein bulb oxygen saturation, and jugular venous pressure (JVP) were continuously measured. Autoregulation was tested during changes in mean arterial blood pressure (MAP) within a range of 40-80 mm Hg, induced by sodium nitroprusside and phenylephrine before (control) and during additional isoflurane administration to an EEG burst-suppression level of 6-9/min. Isoflurane induced a 27% decrease in CBFV (P < 0.05) and a 13% decrease in COE (P < 0.05) compared with control. The slope of the positive relationship between CBFV and cerebral perfusion pressure (CPP = MAP - JVP) was steeper with isoflurane (P < 0.05) compared with control, as was the slope of the negative relationship between CPP and COE (P < 0.05). We conclude that burst-suppression doses of isoflurane decrease CBFV and impair autoregulation of cerebral blood flow during mildly hypothermic CPB. Furthermore, during isoflurane administration, blood flow was in excess relative to oxygen demand, indicating a loss of metabolic autoregulation of flow.

IMPLICATIONS

The effects of isoflurane on cerebral blood flow velocity (CBFV) and oxygen extraction (COE) as a function of perfusion pressure were studied. When added to fentanyl anesthesia, isoflurane induced a 27% and 13% decrease in CBFV and COE, respectively. CBFV became more pressure-dependent with isoflurane indicating an impaired autoregulation.

Rectally administered diclofenac (Voltaren) reduces vomiting compared with opioid (morphine) after strabismus surgery in children

BACKGROUND

Nausea, vomiting and pain are common complications after strabismus surgery in children. Diclofenac, a non-steroid anti-inflammatory drug, is widely used to treat acute and chronic pain but there are few reports of its use given rectally in children undergoing strabismus surgery. This open randomised study was designed to investigate the analgesic and anti-emetic properties of rectally administered diclofenac compared with opioid (morphine) given i.v. in connection with strabismus surgery in children.

METHODS

After obtaining approval from the local ethics committee and written informed consent from the parents, 50 ASA class I-II children, 4-16 years of age, were randomised to receive either rectally administered diclofenac (Voltaren) 1 mg/kg or i.v. opioid (morphine) 0.05 mg/kg perioperatively. The children were consecutively operated upon from May 1999 to January 2001. Anaesthesia was induced with fentanyl and propofol and maintained with propofol. Nitrous oxide was omitted. The postoperative pain was assessed after arrival at the post anaesthesia care unit (PACU) by using the validated Wong and Baker scale (FACES) Pain Rating Scale. Postoperative nausea and vomiting (PONV) was assessed by measuring the frequency of vomiting and the degree of nausea.

RESULTS

In the diclofenac group the incidence of PONV during the first 24 h was 12% (of which one child had severe vomiting). The incidence of PONV was much higher, 72% (P = 0.0000), in the morphine group, where 56% of the children also had severe vomiting. There were no difference in pain score between the two groups. Recovery time at the PACU was longer (P < 0.002) and the postoperative analgesic requirement higher in the morphine group (10 vs. 5 children). No children needed overnight admission to the hospital.

CONCLUSION

Diclofenac given rectally is an effective analgesic for this kind of surgery and gives less postoperative nausea than i.v. morphine. No serious adverse events were observed.