Experts from the five Nordic countries offer consensus recommendations for safe clinical practice of neuraxial blocks and how to minimize the risks of serious complications from spinal bleeding. A brief version of the recommendations is available on http://www.ssai.info.

Objective To assess whether intrapartum acidosis affects specific components of fetal heart rate variability.Design Prospective clinical study.Setting Twelve Nordic delivery units.Subjects Fetal heart rate variability was studied in 334 fetuses divided into two groups according to cord pH value: the acidotic group (cord arterial pH <7.05 at birth, n ¼ 15) and the control group (cord arterial pH !7.05 at birth, n ¼ 319). Methods In spectral analysis of fetal heart rate variability, frequencies were integrated over the total frequency band (0.04 -1.0 Hz), low-frequency band (0.04 -0.15 Hz) and high-frequency band (0.15 -1.0 Hz). We also calculated the low-to-high frequency ratio. Main outcome measures The spectral bands of fetal heart rate variability were compared between the acidotic and control fetuses. Results We found that during the last hour of monitoring, baseline fetal heart rate gradually decreased, whereas total, low-frequency and high-frequency fetal heart rate variability initially increased but then, near the delivery, decreased in the acidotic fetuses when compared with the controls. Low-to-high frequency ratio was greater in the acidotic group during the whole study period (P ¼ 0.002). Cord artery pH was inversely associated with total fetal heart rate variability (P < 0.001), low-frequency fetal heart rate variability (P < 0.001) and low-to-high frequency ratio (P ¼ 0.004). Conclusions Marked fetal acidosis was associated with frequency-specific changes in fetal heart rate variability as reflecting the compensation ability of autonomic nervous activation during the last hour of labour.

Inhaled supranormal partial pressure of oxygen induces bradycardia and peripheral vasoconstriction. The exact mechanism of the decreasing heart rate is not clear, but the autonomic nervous system is partly involved. In the present study the role of the autonomic nervous system in hyperoxic bradycardia was evaluated by using the power spectral analysis of heart rate variability. Ten healthy volunteers participated in four experiments: (i) hyperbaric oxygen treatment (100% oxygen at 2.5 ATA), (ii) hyperbaric air treatment (O2 21% at 2.5 ATA), (iii) oxygen treatment at normal pressure (100% O2, 1 ATA) and (iv) air breathing at normal pressure (21% O2, 1 ATA). During the experiments, ECG was registered and subjected to power spectral analysis. The volunteers rated their perception of temperature, ear discomfort, sweating and excitement on a visual analogue scale. Statistical comparison of the results of the four trials was conducted with a two-way ANOVA for repeated measurements. Heart rate decreased during all interventions, but there were no statistically significant differences between the sessions. High frequency variability of heart rate variability and Hayano's index of HF power increased and LF/HF ratio decreased with increasing partial pressure of oxygen. Our results suggest, that normobaric and hyperbaric hyperoxia increase parasympathetic influence in the regulation of the heart.

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There is growing evidence of a strong association between the compromised autonomic nervous system and sudden cardiac death. Heart rate variability (HRV) measures are widely used to measure alterations in the autonomic nervous system. Several studies with cardiac patients show that decreased HRV as well as baroreceptor dysfunction are more powerful predictors for sudden cardiac death than established clinical predictors such as left ventricular ejection fraction. One-third of all postoperative complications and more than half of the deaths are due to cardiac complications. Several risk indices are useful for immediate perioperative short-term, but not for long-term outcome risk stratification of an individual patient. Currently, there are no clinically assimilated methods for long-term postoperative risk assessment. Recently, few studies have shown that preoperatively decreased HRV can independently predict postoperative long-term mortality. Further studies with surgical patients are needed to establish a possible predictive value of preoperative baroreceptor dysfunction, alone and combined with HRV, for short- and long-term postoperative outcome.

The centrally acting alpha2-adrenoceptor agonists clonidine and dexmedetomidine have been used with success to provide haemodynamic stability for patients undergoing surgery. Particularly in the case of patients with overt or underlying cardiac disease the actions of alpha2-adrenoceptor agonists, which include maintenance of stable systemic blood pressure and low heart rate and a reduction in overall oxygen consumption, can be expected to reduce the risk of procedure-related cardiac events. This expectation has been corroborated in clinical trials with clonidine, dexmedetomidine and mivazerol and meta-analyses; additional large controlled trials would be instructive in establishing a robust estimate of the scale of the benefit. In addition, alpha2-adrenoceptor agonists used as premedication have been shown to substantially reduce anaesthetic requirements among surgical patients, and the use of these agents has been associated with a reduced risk of postoperative delirium, which may be expected to improve considerably the postoperative course for at-risk patients. Dexmedetomidine is the only alpha2-adrenoceptor agonist currently approved for use in the intensive care unit. A distinctive feature of dexmedetomidine in that setting is that in addition to haemodynamic stability it confers a distinctive and advantageous quality of sedation: patients are tranquil but responsive to requests from attending staff. This review examines the pharmacological principles underlying the use of alpha2-adrenoceptor agonists as adjuncts to surgery and clinical experience in that indication.

Continuous epidural bupivacaine/fentanyl analgesic regimen, started preoperatively, reduces the amount of myocardial ischaemia in elderly patients with hip fracture.

BackgroundDexmedetomidine, an alpha2-adrenoceptor agonist, has been evaluated as an adjunct to anesthesia and for the delivery of sedation and perioperative hemodynamic stability. It provokes dose-dependent and centrally-mediated sympatholysis. Coronary artery bypass grafting (CABG) with extracorporeal circulation is a stressful procedure increasing sympathetic nervous system activity which could attenuate renal function due the interrelation of sympathetic nervous system, hemodynamics and renal function. We tested the hypothesis that dexmetomidine would improve kidney function in patients undergoing elective CABG during the first two postoperative days.MethodsThis was a double-blind, randomized, parallel-group study. Patients with normal renal function and scheduled for elective CABG were randomized to placebo or to infusion of dexmedetomidine to achieve a pseudo steady-state plasma concentration of 0.60 ng/ml. The infusion was started after anesthesia induction and continued until 4 h after surgery. The primary endpoint was creatinine clearance. Other variables included urinary creatinine and output, fractional sodium and potassium excretion, urinary potassium, sodium and glucose, serum and urinary osmolality and plasma catecholamine concentrations. The data were analyzed with repeated-measures ANOVA or Cochran-Mantel-Haenszel test.ResultsSixty-six of 87 randomized patients were evaluable for analysis. No significant between-group differences were recorded for any indices of renal function except for a mean 74% increase in urinary output with dexmedetomidine in the first 4 h after insertion of a urinary catheter (p < 0.001). Confidence interval examination revealed that the sample size was large enough for the no-difference statement for creatinine clearance.ConclusionsUse of intravenous dexmedetomidine did not alter renal function in this cohort of relatively low-risk elective CABG patients but was associated with an increase in urinary output.This study was carried out in 1994-1997 and was thus not registered.