SIVAUK Education Section

Stroke volume variation (SVV) is able to predict adequately the individual response to fluid loading. Our objective was to assess whether the SVV measured by a new algorithm (Vigileo^TM; Flotrac^TM) can predict fluid responsiveness.

Forty mechanically ventilated patients undergoing liver transplantation, who needed volume expansion (VE), were included. VE was done with albumin (4%) 20 mlxBMI over 20 min. SVV, pulse pressure variation (PPV), central venous pressure (CVP), and pulmonary artery occlusion pressure (PAOP) were measured immediately before and after VE. Cardiac output (CO) measured by transthoracic echocardiography (CO-TTE) was used to define responder patients if CO increased by 15% or more after VE, or non-responder otherwise. CO obtained with the pulmonary artery catheter (CO-PAC) and with Vigileo (CO-Vigileo) were also recorded.

Five patients were excluded. Seventeen patients were responders (Rs) and 18 were non-responders (NRs). Before VE (i) SVV and PPV were higher in Rs and (ii) CVP and PAOP were lower in Rs. Baseline SVV and PPV correlated with change in CO induced by VE (respectively, r²=0.72, P<0.0001; r²=0.84, P<0.0001). An SVV threshold of >10% discriminated Rs with a sensitivity of 94% and a specificity of 94%. After VE, the decrease in SVV was significantly correlated with the increase in CO (r²=0.51; P<0.0001). There was no difference between the area under the ROC curves of SVV and PPV. After VE, the change in CO-Vigileo was closely correlated with change in CO-TTE (r²=0.74, P<0.0001) and with change in CO-PAC (r²=0.77, P<0.0001).

The SVV obtained by the Vigileo system may be used as a predictor of fluid responsiveness in patients with circulatory failure after liver transplantation. CO-Vigileo is able to track the change in CO induced by VE.

Patients experiencing massive haemorrhage are at high risk of developing coagulopathy through loss, consumption, and dilution of coagulation factors and platelets. It has been reported that plasma fibrinogen concentrations may reach a critical low level relatively early during bleeding, calling for replacement fibrinogen therapy. Cryoprecipitate has been widely used in the past, but more recently, a pasteurized fibrinogen concentrate has become available. We audited the effects of fibrinogen concentrate therapy on laboratory and clinical outcome in patients with massive haemorrhage.

We identified 43 patients over the previous 2 yr to whom a fibrinogen concentrate had been administered as treatment for hypofibrinogenaemia during serious haemorrhage. Platelet count, P-fibrinogen, activated partial thromboplastin time (APTT), prothrombin time (PT), D-dimer, and volume of blood lost were obtained from medical and laboratory records. Numbers of units of red blood cells (RBC), fresh frozen plasma (FFP), and pooled platelet concentrates were recorded before and after fibrinogen substitution.

A significant increase in plasma fibrinogen concentration was observed after fibrinogen concentrate therapy. Platelet counts and fibrin D-dimer values remained unchanged, whereas the APTT and PT improved significantly. Requirements for RBC, FFP, and platelets were significantly reduced. Blood loss decreased significantly.

Off-label substitution therapy with a fibrinogen concentrate generally improved global laboratory coagulation results and as supplementary intervention, appeared to diminish the requirements for RBC, FFP, and platelet substitution in this patient cohort.

Morbidity and mortality are higher in patients with poor preoperative cardiorespiratory reserve. This study aimed to ascertain fitness and therefore risk in elective patients, comparing three measures: Duke Activity Status Index (DASI) questionnaire, incremental shuttle walk test (ISWT), and cycle cardiopulmonary exercise testing (CPET). We looked for correlation between the measures and for thresholds on the questionnaire or shuttle test which could identify fit patients and render CPET unnecessary.

A prospective cohort trial of 50 patients having intra-abdominal surgery. Each performed DASI, ISWT, and CPET during a single visit to the hospital.

There was a significant correlation between measured oxygen consumption and both ISWT and DASI. Receiver operator curve showed both the shuttle walk test and the DASI are sensitive and specific predictors of VO₂peak >15 ml O₂ kg^–1 min^–1 and anaerobic threshold (AT) >11 ml O₂ kg^–1 min^–1. Thirty-two patients would be considered lower risk, having achieved both VO₂peak and AT cut-offs. Setting an ISWT threshold of 360 m identified 13 of the lower risk patients [positive predictive value (PPV) 1.0, negative predictive value (NPV) 0.49]. Setting a DASI threshold score of 46 identified nine lower risk patients (PPV 1.0, NPV 0.44).

We found a significant correlation between the tests. However, many patients with poor questionnaire scores or shuttle walks had satisfactory CPET results. Hence, the ability of either simple test to determine risk in a heterogeneous surgical population is poor. CPET provides an objective measurement of cardiopulmonary fitness; however, evidence for this information improving patient outcome is limited and requires further research.

Intraoperative stress may suppress the adaptive immune system. Abolished proinflammatory lymphocyte function is associated with higher risk of infection and postoperative complications. We hypothesized that thoracic epidural anaesthesia (TEA) reduces intraoperative stress and thus attenuates lymphocyte decrease and impairment of proinflammatory lymphocyte function.

Fifty-four patients undergoing major abdominal surgery who had a thoracic epidural catheter inserted were studied. In the TEA-I group, this catheter was used for intraoperative analgesia, whereas the TEA-P group received systemic opioids during surgery. In both groups, patient-controlled epidural analgesia was used for postoperative pain management. Blood samples for immune analyses were obtained before induction of anaesthesia, 2 h after skin incision, and at days 1 and 4 after surgery. Lymphocyte subpopulations, expression of human leucocyte antigen (HLA)-DR on monocytes, plasma concentrations of interleukin (IL)-10, interferon- (IFN-), and IL-12, and concanavalin-A-stimulated concentrations of IFN- and IL-10 were measured. Intraoperative data including bispectral index and plasma concentrations of epinephrine/cortisol were analysed; APACHE-II, SAPS II, and additional postoperative data were documented.

Plasma concentrations of epinephrine and cortisol were significantly lower in the TEA-I patients during surgery. IFN-/IL-10 ratio was significantly higher in the TEA-I group from 2 h after skin incision until day 1. Lymphocyte numbers and T-helper cells were significantly higher in the TEA-I group at day 1, whereas no significant differences were detected among IL-12, HLA-DR, and postoperative clinical course.

Intraoperative use of thoracic epidural catheter reduced stress response and prevented stress-induced perioperative impairment of proinflammatory lymphocyte function.

Pharmacokinetic/pharmacodynamic (PK/PD) parameters of neuromuscular blocking agents (NMBAs) are generally assumed to be dose-independent. To our knowledge, there are very few clinical reports where the PK/PD parameters of a NMBA were derived separately for each dose group during a formal dose-ranging study. The primary objective of this study was to challenge a potential dose-dependency of cisatracurium PK/PD parameters by conducting a well-controlled experimental study.

Eight dogs were anaesthetized with pentobarbital and mechanically ventilated. Two doses of cisatracurium (1.5xED₉₅ and 6xED₉₅) were administered in a randomized cross-over design after an appropriate washout period. Neuromuscular function was monitored using train-of-four (TOF) stimulation. Arterial blood was sampled continuously for the first minute after cisatracurium injection and at frequent intervals thereafter. Cisatracurium plasma concentrations were determined by high performance liquid chromatography analysis. PK/PD modelling of individual data sets was performed with NONMEM using a non-parametric approach and a descriptive sigmoid E_max model.

Cisatracurium PKs were linear over the dose range studied. Using non-parametric PK/PD analysis, mean values for plasma–effect compartment equilibration delay (k_e0) were 0.0600 vs 0.1278 min^–1 (P<0.05) and sensitivity (EC₅₀) were 323 vs 235 ng ml^–1 (P<0.05) for the high and low doses, respectively.

A dose-dependent effect on the PK/PD parameters of cisatracurium has important clinical implications as an accurate estimate of the EC₅₀ is desirable. PK/PD parameters derived after intubating bolus doses of cisatracurium would be more reliable.

The Simplified Acute Physiology Score (SAPS) 3 has recently been developed, but not yet validated in surgical intensive care unit (ICU) patients. We compared the performance of SAPS 3 with SAPS II and the Acute Physiology and Chronic Health Evaluation (APACHE) II score in surgical ICU patients.

Prospectively collected data from all patients admitted to a German university hospital postoperative ICU between August 2004 and December 2005 were analysed. The probability of ICU mortality was calculated for SAPS II, APACHE II, adjusted APACHE II (adj-APACHE II), SAPS 3, and SAPS 3 customized for Europe [C-SAPS3 (Eu)] using standard formulas. To improve calibration of the prognostic models, a first-level customization was performed, using logistic regression on the original scores, and the corresponding probability of ICU death was calculated for the customized scores (C-SAPS II, C-SAPS 3, and C-APACHE II).

The study included 1851 patients. Hospital mortality was 9%. Hosmer and Lemeshow statistics showed poor calibration for SAPS II, APACHE II, adj-APACHE II, SAPS 3, and C-SAPS 3 (Eu), but good calibration for C-SAPS II, C-APACHE II, and C-SAPS 3. Discrimination was generally good for all models [area under the receiver operating characteristic curve ranged from 0.78 (C-APACHE II) to 0.89 (C-SAPS 3)]. The C-SAPS 3 score appeared to have the best calibration curve on visual inspection.

In this group of surgical ICU patients, the performance of SAPS 3 was similar to that of APACHE II and SAPS II. Customization improved the calibration of all prognostic models.

The influence of changes in body position relevant to neuraxial blockade on the location of the spinal cord and related neural structures has not been fully quantified. Our aim was to determine the changes, if any, that occur in the location of the spinal cord tip [equivalent to the tip of the conus medullaris (CM)] and nerve roots when an individual moves from the supine to the left lateral position with knees and hips flexed.

We used magnetic resonance imaging to determine movement of the spinal cord tip and associated structures in 30 adult volunteers.

The tip shifted both anteriorly [average 6.3 mm, standard deviation (sd) 2.15 mm; P<0.001] and laterally towards the dependent side (average 1.63 mm, sd 1.19 mm; P<0.001). Although we observed anterior shift in all 30 volunteers, lateral movement did not occur in seven. Movement along the cranio-caudal axis was not statistically significant.

Both the CM and associated nerve roots shift consistently and significantly anteriorly when moving from the supine to the lateral position with knees and hips flexed, which may provide a greater margin of safety during neuraxial blockade than might be predicted. However, the absence of significant cranial movement of the CM along the cranio-caudal axis still makes the spinal cord vulnerable to injury during lumbar neuraxial blockade.

It would be useful to have an open-source electroencephalographic (EEG) index of -amino-butyric acid (GABA)-ergic anaesthetic drug effect that is resistant to eye-blink artifact, responds rapidly to changes in EEG pattern, and can be linked to underlying neurophysiological and neuropharmacological mechanisms that control the conscious state.

The EEG waveform can be described as a sequence of ordinal patterns. The permutation entropy (PE) describes the relative occurrence of each of these patterns. It is high (1.0) when the signal has predominantly high frequencies and low (0.4) when the signal consists of only low frequencies. The response of the PE to various computer-generated EEG-like waveforms was assessed. A composite PE index (CPEI) was developed, which was the sum of two simple PEs and included a small measurement-noise threshold (0.5 µV). We also applied the CPEI to two small pilot EEG data sets from patients receiving sevoflurane (n=21) or propofol (n=9) anaesthesia.

With minimal pre-processing or artifact rejection, the CPEI reliably tracked the anaesthetic-related EEG changes, namely loss of high frequencies, spindle-like waves, and delta waves. Using NONMEM, it was possible to construct adequate pharmacokinetic–pharmacodynamic models from the data. The CPEI was comparable with models derived using the bispectral index [BIS R²=0.88 (0.08) vs CPEI R²=0.91 (0.06) for the propofol data] and M-entropy indices [M-entropy R²=0.91 (0.06) vs CPEI R²=0.87 (0.09) for the sevoflurane data].

PE of the EEG shows promise as a simple measure of GABAergic anaesthetic drug effect.

The optimal dose of oxytocin at Caesarean section is unclear. Oxytocin may cause adverse cardiovascular effects, including tachycardia and hypotension, whereas an inadequate dose can result in increased uterine bleeding. We compared the effects of two doses of oxytocin in a randomized double-blind trial.

Eighty patients undergoing elective Caesarean section received an i.v. bolus of either 2 or 5 units (u) of oxytocin after delivery, followed by an oxytocin infusion of 10 u h^–1. All received combined spinal–epidural anaesthesia with arterial pressure maintained by a phenylephrine infusion. We compared changes in heart rate (HR), mean arterial pressure (MAP), blood loss, uterine tone, the need for additional uterotonic drugs, and emetic symptoms.

There was a greater increase in mean (sd) HR in patients who received 5 u of oxytocin [32 (17) beats min^–1] than in those who received 2 u [24 (13) beats min^–1] (P=0.015). There was a larger decrease in MAP in patients who received 5 u [13 (15) mm Hg] than in those who received 2 u [6 (10) mm Hg] (P=0.030). The frequency of nausea and antiemetic use was higher after 5 u (32.5%) than 2 u (5%) (P=0.003). There were no differences in blood loss, uterine tone, or requests for additional uterotonic drugs (17.5% in both groups).

In elective Caesarean section, a 2 u bolus of oxytocin results in less haemodynamic change than 5 u, with less nausea and no difference in the need for additional uterotonics.

Propofol clearance is lower in neonates than in adults and displays extensive interindividual variability, in part explained by postmenstrual age (PMA) and postnatal age (PNA). Since propofol is almost exclusively cleared metabolically, urinary propofol metabolites were determined in early life and compared with similar observations reported in adults.

Twenty-four hours urine collections were sampled after a single i.v. bolus of propofol (3 mg kg^–1) in neonates undergoing procedural sedation. Clinical characteristics (PMA, PNA, weight, and cardiopathy) were recorded. Urine metabolites [propofol glucuronide (PG), 1- and 4-quinol glucuronide (QG)] were quantified using high-pressure liquid chromatography. Urine recovery (% administered dose) and the contribution of PG and QG to urinary elimination were calculated. Data were reported by median and range, analysed by Mann–Whitney U or Spearman's rank.

Eleven neonates (median PNA 11 days, PMA 38 weeks) were included. Median propofol metabolite recovery was 64% (range 34–98%). PG contributed 34% (range 8–67%) and QG 65% (range 33–92%). There was no significant correlation between either PMA, PNA, or cardiopathy and propofol metabolites. Compared with adults, the contribution of PG (34% vs 77%) was lower and the contribution of QG (65% vs 22%) was higher in neonates.

Propofol metabolism in neonates differs from adults, reflecting the age-dependent limited glucuronidation capacity. Hydroxylation to quinol metabolites already contributes to propofol metabolism. These differences likely explain the PMA- and PNA-dependent reduced propofol clearance in neonates.

Approximately 30–80% of postoperative patients complain about moderate to severe post-surgical pain, indicating that postoperative pain treatment is still a problem.

We analysed prospectively collected data on patients in a university hospital receiving systemic and epidural patient-controlled analgesia and continuous peripheral nerve block (CPNB) documented by the acute pain service team in a computer-based system.

Of 18 925 patients visited in the postoperative period between 1998 and 2006, 14 223 patients received patient-controlled epidural analgesia (PCEA), 1591 i.v. patient-controlled analgesia (IV-PCA), 1737 continuous brachial plexus block, and 1374 continuous femoral/sciatic nerve block. Mean dynamic and resting pain scores (VAS 0–100) were significantly lower for peripheral or neuroaxial regional analgesia compared with patient-controlled systemic opioid analgesia (P<0.05). The risk of a symptomatic spinal mass lesion including epidural haematoma (0.02%; 1:4741) or epidural abscess (0.014%; 1:7142) after PCEA was 1:2857 (0.04%). Neurological complications after CPNB occurred in two patients who received interscalene brachial plexus block.

We demonstrated that PCEA, IV-PCA, and CPNB are safe and efficient. Although all of these treatment strategies provide effective analgesia, PCEA and CPNB provided superior pain relief compared with IV-PCA. We demonstrated that serious complications of analgesic techniques are rare but possibly disastrous necessitating a close supervision by an acute pain service. We found a low rate of adverse effects including hypotension and motor impairment and a low incidence of epidural haematoma for thoracic PCEA compared with lumbar PCEA.

Block of parietal nociceptive afferent nerves using continuous wound infiltration with local anaesthetics may be beneficial in multimodal postoperative pain management. The effectiveness of continuous wound infusion of ropivacaine for postoperative pain relief after open nephrectomy was analysed in a prospective, randomized, double-blinded, placebo-controlled trial.

One hundred and sixty-eight patients were randomized to either 0.5% ropivacaine (ON-Q group) or 0.9% NaCl (control group), using an elastomeric pump which delivered 4 ml h^–1 over 48 h through two multiholed Soaker^® catheters placed between the transverse and the internal oblique muscles and the s.c. space. All patients received a standard postoperative pain management protocol, including patient-controlled analgesic morphine and ketorolac. Outcomes measured over 48 h after operation were visual analogue scale (VAS) and incident (i) VAS pain scores, morphine consumption, and side-effects; time to bowel function recovery; and mean length of hospitalization.

Side-effects were similar between the two groups. VAS and i-VAS pain scores, morphine consumption [11.5 (0.27) vs 21.8 (0.37) mg; P<0.001], time to bowel recovery [21.8 (0.4) vs 33.6 (0.9) h; P<0.001], and mean length of hospitalization [2.1 (0.03) vs 3.2 (0.1) days; P<0.001] were significantly reduced in the ON-Q group. Cost analysis revealed an overall savings of ~273 euros per patient in the ON-Q group.

Continuous surgical wound infusion with ropivacaine improved pain relief and accelerated recovery and discharge reducing overall costs of care.

Fast onset and short duration are prominent properties of the amide-type local anaesthetic articaine. Similar to bupivacaine, a hyperbaric solution of articaine may produce faster onset and shorter duration of spinal anaesthesia than a plain solution.

Patients undergoing open inguinal hernia repair received in random order articaine 84 mg in either hyperbaric (HyperA, n=49) or plain solution (PlainA, n=48) intrathecally. A blinded observer tested the dermatomal spread (pinprick) and motor block (Bromage scale).

Median (range) onset time to the T₁₀ dermatome was 2 (2–8) (n=46) and 6 (2–30) min (n=39) (P<0.001), and the duration of the sensory block at (or above) the T₁₀ dermatome was 86 (39–148) and 69 (15–118) min (P=0.007), in Groups HyperA and PlainA, respectively. Peak sensory block was greater in Group HyperA T₄ (L₂–C₂) than in Group PlainA T₈–T₇ (L₃–T₃) dermatome, median (range), P<0.001. Spread of the block to the cervical dermatomes associated with hypotension occurred in three patients of Group HyperA (one patient C₂ and two C₄). The sensory block resolved to the S₂ dermatome significantly faster in Group HyperA, 2.5 (1.5–4.5) h, than in Group PlainA, 3.5 (2.0–4.5) h (P<0.001). Median duration of the motor block was significantly shorter in Group HyperA, 2.0 (1.3–3.5) vs 3.0 (1.5–4.0) h (P<0.001).

Hyperbaric articaine 84 mg had a faster onset and shorter duration of spinal anaesthesia than the plain solution.

Retrobulbar anaesthesia allows eye surgery in awake patients. Severe complications of the blind techniques are reported. Ultrasound-guided needle introduction and direct visualization of the spread of local anaesthetic may improve quality and safety of retrobulbar anaesthesia. Therefore, we developed a new ultrasound-guided technique using human cadavers.

In total, 20 blocks on both sides in 10 embalmed human cadavers were performed. Using a small curved array transducer and a long-axis approach, a 22 G short bevel needle was introduced under ultrasound guidance lateral and caudal of the eyeball until the needle tip was seen 2 mm away from the optic nerve. At this point, 2 ml of contrast dye as a substitute for local anaesthetic was injected. Immediately after the injection, the spread of the contrast dye was documented by means of CT scans performed in each cadaver.

The CT scans showed the distribution of the contrast dye in the muscle cone and behind the posterior sclera in all but one case. No contrast dye was found inside the optic nerve or inside the eyeball. In one case, there could be an additional trace of contrast dye behind the orbita.

Our new ultrasound-guided technique has the potential to improve safety and efficacy of the procedure by direct visualization of the needle placement and the distribution of the injected fluid. Furthermore, the precise injection near the optic nerve could lead to a reduction of the amount of the local anaesthetic needed with fewer related complications.

Airway Scope is a new videolaryngoscope which requires less cervical movement during intubation than direct laryngoscopy. Thus, in patients wearing a rigid cervical collar, we compared the efficacy of the Airway Scope and the gum elastic bougie with Macintosh laryngoscope during tracheal intubation.

Anaesthesia was induced with propofol, fentanyl, and rocuronium. A rigid cervical collar was applied, and patients were randomly assigned to tracheal intubation with an Airway Scope (n=48) or multiple-use gum elastic bougie with Macintosh laryngoscope (n=48). Measurements included intubation time, gum elastic bougie insertion time, intubation success rate, and insertion and intubation attempts. Airway complications were also recorded.

The time required for successful intubation was significantly shorter with the Airway Scope compared with the gum elastic bougie with Macintosh laryngoscope [mean (sd) 34 (13) vs 49 (27) s, P=0.001], although the overall success rate of the Airway Scope (100%) compared with the gum elastic bougie with Macintosh laryngoscope (90%) did not reach the statistical significance (P=0.056). Oesophageal intubation (n=8) occurred only with the gum elastic bougie with Macintosh laryngoscope. Incidence of mucosal trauma and lip injury was similar with each device. No dental injury or hypoxia occurred with either device.

The Airway Scope shortens intubation time, is less likely to result in oesophageal intubation, and may offer a marginally higher intubation success rate in patients with simulated restricted neck mobility.

Single-lung ventilation (SLV) during thoracic surgery causes important cardiopulmonary disturbances. Absolute cerebral oximetry was used to determine the incidence and magnitude of the decrease in cerebral oxygen saturation (Sct_o2) in patients undergoing SLV during thoracic surgery.

Data were obtained from 20 consecutive patients undergoing thoracic surgery and necessitating SLV of more than 1 h. The FORESIGHT^TM (CASMED, USA) absolute oximeter was used to measure left, right, and average absolute Sct_o2 every 5 min from the awake state to extubation. Bispectral index and standard monitoring parameters were also recorded every 5 min. Blood gas analysis was performed every 15 min. Data median (IQR) (range) were analysed using repeated-measures anova and Spearman’s correlation test, P<0.05.

Patients [median age 65 yr (range 46–75)] showed an absolute Sct_o2 of 80% (78, 82) (74–87) in the awake state, which decreased to a minimum Sct_o2 value of 63% (57, 65) (53–73) during SLV to recover to an Sct_o2 of 71% immediately after extubation. During SLV, all patients had a decrease of more than 15% of the initial Sct_o2 and 70% of patients had a decrease of more than 20%. The decrease in Sct_o2 was not correlated with any standard clinical parameters, for example, arterial pressure, blood loss, peripheral oxygen saturation, or Pa_o2.

Thoracic surgery with SLV seems to be associated with a significant decrease of Sct_o2 in the majority of patients. Parameters such as peripheral oxygen saturation or Po₂ which are used to guide SLV during thoracic surgery are not sufficient to detect significant cerebral oxygen desaturations.