Summary

Background and objective: Placement of central venous catheters in patients is associated with several risks including endocardial lesions and dysrhythmias. Correct positioning of central venous catheters in the superior vena cava is essential for immediate use. The objective of a first study was to evaluate the signal quality of an intravascular electrocardiogram (ECG) during position control using a guidewire compared with the customary fluid column-based ECG system, and to assess its efficacy of correct placement of the central venous catheter. A second study tested if dysrhythmias can be avoided by intravascular ECG monitoring during catheter and guidewire advancement.

Methods: The jugular or subclavian vein of 40 patients undergoing heart surgery or who were being treated in the intensive care unit was cannulated. Intravascular ECGs were recorded during position control, and guidewire and water column lead were compared in the same patient with regard to the quality of the ECG reading and P-wave enhancement. In another 40 patients, the guidewire was inserted only 10 cm and the central venous catheter advanced under guidewire ECG control. Correct position of all the central venous catheters was confirmed by chest radiography.

Results: All central venous catheters were correctly positioned in the superior vena cava. For the same catheter position, the P-wave was significantly larger in the guidewire ECG than in the fluid column system. No changes in the quality of the ECG were detected when the guidewire was advanced or withdrawn by 1 cm relative to the catheter tip. Cardiac dysrhythmias were not seen during ECG-monitored advancement of the guidewire.

Conclusions: ECG quality using a guidewire lead is superior to the water column-based system. Furthermore, it is independent from the exact position of the guidewire as related to the tip of the catheter. Using intravascular guidewire ECG during advancement can prevent induction of dysrhythmias.

Summary

Background and objective: Although electrocardiography (ECG) guidance of central venous catheters (CVCs) is traditionally thought to detect the entrance into the right atrium (RA), there is little evidence in the literature to confirm this. We previously observed a high incidence of left-sided CVCs abutting the wall of the superior vena cava (SVC), even when the catheters were advanced past the point of increased P-wave amplitude. Our hypothesis was that this ECG amplitude signal is actually detecting the pericardial reflection rather than the RA. The goal of the study was to position catheter tips under ECG guidance outside the RA.

Methods: One-hundred central venous triple-lumen catheters inserted either via the right or the left internal jugular veins, respectively, were analysed in cardiac surgical patients. The position of the catheter tip was ascertained by ECG. Method A: A Seldinger guide-wire in the distal lumen served as exploring electrode, the respective insertion depth was recorded. Method B: The middle lumen (port opening 2.5 cm from the catheter tip, thus the catheter was advanced more towards the atrium) filled with a saline 10% fluid column served as the exploring electrode, and the insertion depth was recorded again. Descriptive data are given as mean ± standard deviation.

Results: On average, the catheters were advanced by the expected 2 ± 0.3 cm using Method B beyond the initial insertion by Method A. All 100 CVCs were finally correctly positioned in the SVC and confirmed by transoesophageal echocardiography. When chest radiography was performed after surgery not a single catheter abutted the lateral wall of the SVC.

Conclusion: Since both methods detected the same structure, and catheters placed by Method B did not result in intra-atrial CVC tip position, the first increase in P-wave amplitude does correspond to a structure in the SVC, most likely the pericardial reflection.

Summary

Background and objective: To compare the accuracy of prognoses made by intensive care physicians with the performance of two indicators, the original Simplified Acute Physiology Score (SAPS) II and a modified version optimized to the patient sample.

Methods: Data from 412 patients consecutively admitted to intensive care units of Göttingen University Hospital, Germany, were collected according to the original score criteria. Information necessary for the computation of SAPS II and the vital status on hospital discharge was recorded. To customize the original SAPS II in our cohort, the database was randomly divided into two subgroups. Logistic regression analysis with physiological values as explanatory variables was used. A bootstrap procedure completed the process. Furthermore, physicians were asked to indicate their prognostic judgement concerning the patients’ hospital mortality.

Results: Discrimination analysis showed the following areas under receiver operating characteristic curves: physicians’ prognoses 0.84 (confidence interval (CI): 0.79–89), SAPS II 0.75 (CI: 0.69–0.80) and customized SAPS 0.72 (CI: 0.66–0.78). The physician's forecast was significantly better, while the customized and the original SAPS were not substantially different as regards their accuracy.

Conclusions: Prognoses made by physicians are superior to objective models. This may result from more extensive knowledge and other kinds of information available to clinicians. A clinician's action also depends on his/her prognosis at the beginning of the treatment, giving raise to a possible correlation between medical outcome and the clinician's prognosis. Our findings indicate that physicians do not limit their prognosis to the objective factors at their disposal, but indicate that they base their decisions on experience and individual observations.

Summary

Background and objective: We hypothesized that remifentanil–propofol cardiac anaesthesia, plus administration of pirinitramide (piritramide) upon cessation of the remifentanil infusion, would be associated with a shorter time to tracheal extubation than alfentanil–propofol anaesthesia, without the occurrence of major haemodynamic instability.

Methods: Haemodynamic stability and recovery characteristics of two remifentanil infusion regimens (0.5 μg kg−1 min−1; 0.25 μg kg−1 min−1) were therefore compared with an alfentanil infusion regimen (1 μg kg−1 min−1), in combination with target-controlled infusion of propofol, in a randomized blinded trial in 75 coronary artery surgery patients.

Results: Pirinitramide provided good postoperative analgesia without prolonging extubation times: median extubation time in minutes after stopping the opioid-sedative drugs was 300 in the higher-dose remifentanil group and 270 in the lower-dose remifentanil group and alfentanil group (P = 0.606). Significant time-by-treatment interactions were seen for systolic arterial pressure (P = 0.015), mean arterial pressure (P = 0.009) and diastolic arterial pressure (P = 0.006). No significant interaction (P = 0.489) and no constant treatment effect were seen for heart rate (P = 0.288). Time effects were highly significant (P < 0.0001) for all haemodynamic variables. Heart rate remained stable in all groups. In the higher-dose remifentanil group, blood pressure was significantly different and lower during surgery and in this group less bolus doses of the opioid-sedative drugs (P = 0.015) had to be given.

Conclusion: The higher-dose remifentanil infusion provided superior suppression of haemodynamic responses to noxious stimuli with better haemodynamic stability.

Summary

Background and objective: Outcome prediction and evaluation of intensive care unit (ICU) performance using severity of illness scoring is a tool for the estimation of effectiveness and quality of intensive care. We used the simplified acute physiology score (SAPS) II system to evaluate ICU performance.

Methods: The present study is a prospective observational study in an ICU at Vilnius University Emergency Hospital, Lithuania. The observed death rate was compared with the predicted death rate calculated using SAPS II system. The ability of the SAPS II prognostic system to predict the probability of hospital mortality was assessed with discrimination and calibration measures.

Results: Two-thousand-and-sixty-seven patients consecutively admitted to the ICU were studied. The median SAPS II score on the first ICU day was 29. The SAPS II system showed a good ability to separate those patients predicted to live from those predicted to die (an area under the receiver operating characteristic curve was 0.883). The calibration curve demonstrated under-prediction of the actual death rate (Hosmer–Lemeshow goodness-of-fit test, χ2 = 56.98; df = 8; P < 0.001). The observed mortality was higher than predicted by the SAPS II equation (observed to predicted ratio is 1.28).

Conclusions: The SAPS II system is a useful tool for the assessment of ICU performance. This system demonstrated a good ability of discrimination, but an under-prediction of the actual mortality rate, in Lithuanian ICUs.

Summary

Background and objective: Since the moribund hypodynamic phase of septic shock has primarily been studied in small animal models, the objective of this study was to investigate the usefulness of infusing Salmonella typhosa endotoxin at incrementing doses to establish an ovine model of hypodynamic endotoxaemia.

Methods: In a prospective laboratory experiment, eight adult ewes were instrumented for a chronic study. Following a baseline measurement in the healthy state, a continuous endotoxin infusion was started with 10 ng kg−1 min−1 and was doubled every hour seven times. Haemodynamics, key variables of oxygen transport, and arterial lactate concentrations were determined every hour.

Results: In a dose-dependent manner, endotoxin infusion caused pulmonary hypertension, decreased cardiac output and mean arterial pressure, increased heart rate, and to a certain extent, systemic vascular resistance index. Following 4 h of endotoxaemia, the maximum decrease in cardiac output occurred (4.8 ± 0.2 vs. 7.6 ± 0.3L min−1; P < 0.001). This was accompanied by tissue dysoxia, represented by decreases in oxygen delivery (797 ± 20 vs. 1041 ± 28 mL min−1), oxygen consumption (277 ± 14 vs. 396 ± 15 mL min−1) and oxygen extraction rate (0.35 ± 0.01 vs. 0.38 ± 0.01%; each P < 0.01), as well as an increase in arterial lactate concentration (1.7 ± 0.1 vs. 0.7 ± 0.1 mmol L−1; P < 0.05).

Conclusions: This large animal model may be helpful to study the pathophysiology responsible for cardiovascular failure, and also new therapeutic approaches relevant to management of hypodynamic circulation in the common setting of progressed systemic inflammation.

Summary

Background and objective: We evaluated the validity of a newly developed pulse dye densitometer for indigo carmine for measuring cardiac output and circulating blood volume.

Methods: Measurements of cardiac output and circulating blood volume were performed with the indigo carmine densitometer during normovolaemia, hypovolaemia and hypervolaemia in nine mongrel dogs under general anaesthesia. The validity was evaluated by comparison of the values of cardiac output and circulating blood volume obtained by the thermodilution technique and the 51Cr-labelled red blood cell method, respectively. We also examined indigo carmine removal by continuous veno-venous haemofiltration after indigo carmine injection.

Results: There was good agreement between dye densitometer- and thermodilution-derived cardiac output (r = 0.885, P < 0.001). The bias and limits of agreement of these values were 0.09 and ± 1.07L min−1 (2 SD, n = 22), respectively. The dye-densitometer-derived circulating blood volume was greater than that of the 51Cr-labelled red blood cell method, and both values showed weak agreement (r = 0.587, P < 0.027). The sieving coefficient of indigo carmine through continuous veno-venous haemofiltration was 0.34 ± 0.06.

Conclusions: These data indicate that indigo carmine densitometry is a reliable method for cardiac output determination, but it overestimates circulating blood volume, probably due to the transition of indigo carmine into the extravascular space in the systemic circulation.

Summary

Background and objective: This study was performed to determine the individual exposure of paediatric operating theatre personnel to sevoflurane and to evaluate the impact of inhalation induction and various airway approaches on exposure to airborne sevoflurane.

Methods: Mean individual environmental (workplace air) exposure to sevoflurane and a biomarker of exposure (urinary sevoflurane) were monitored in 36 subjects (10 anaesthetists, 10 surgeons, 12 nurses and 4 auxiliary personnel) working in two paediatric operating rooms.

Results: Environmental and urinary values were significantly greater in anaesthetists compared with other groups, with median values of 0.65 ppm (interquartile range 1.36; 95th percentile 4.36) for breathing zone sevoflurane and 2.1 μg L−1 urine (interquartile range 2.6; 95th percentile 7.6) for urinary sevoflurane. Anaesthetists exceeded the 2 ppm maximum allowed environmental concentration recommended by the National Institute for Occupational Safety and Health in 4 of 22 cases (18.1%). A positive correlation was found between the number of patients undergoing inhalational induction each day and mean values of breathing zone and urinary sevoflurane. An increase in the number of daily laryngeal mask insertions, or the use of rigid bronchoscopy, are statistically related to higher environmental and urinary values (P < 0.01 and <0.00001 for breathing zone sevoflurane, P < 0.05 and <0.01 for urinary sevoflurane, respectively).

Conclusions: Anaesthesia with sevoflurane can pose a hazard of chronic exposure with anaesthetists having the highest risk. Endotracheal intubation offers considerable protection against exposure. Routine anaesthesia using a standard facemask, a laryngeal mask or rigid bronchoscopy are risk factors for increased anaesthetic exposure.

Summary

Background and objective: We tested the hypothesis that disturbances of the visual pathway following sevoflurane general anaesthesia (a) exist and persist even after clinical discharge criteria have been met and (b) are associated with decreased contrast sensitivity.

Methods: We performed pattern and full-field flash electroretinograms (ERG) in 10 unpremedicated ASA I patients who underwent nitrous oxide/sevoflurane anaesthesia. ERG and contrast sensitivity were recorded preoperatively, immediately after discharge from the recovery room and 2 h after discontinuation of sevoflurane. The time at which the Post Anaesthesia Discharge Score first exceeded 9 was also noted. Data were analysed using paired, one-tailed t-tests and Pearson's correlation coefficient.

Results: On the full-field photopic ERG, b-wave latency was greater at each postoperative time point (31.6 ± 1.1 and 30.8 ± 1.1 ms) compared to preoperatively (30.1 ± 1.1 ms, P < 0.001 and P = 0.03, respectively). Oscillatory potential latencies were greater on discharge from the recovery room compared with pre-anaesthetic values (23.1 ± 3.1 vs. 22.4 ± 3.3 ms, P = 0.01) and returned to baseline by 2 h after emergence from anaesthesia. Also at 2 h after emergence from anaesthesia: (a) P50 latency on the pattern ERG was greater than at baseline (81.5 ± 17.9 vs. 51.15 ± 22.6 ms, P = 0.004); (b) N95 amplitude was less compared to pre-anaesthetic values (2.6 ± 0.5 vs. 3.3 ± 0.4 μV, P = 0.003) and (c) contrast sensitivity was less compared to baseline values (349 ± 153 vs. 404 ± 140, P = 0.048). A positive correlation was demonstrated between contrast sensitivity and both N95 amplitude and b-wave latency (r = 0.99 and r = −0.55 at significance levels of P < 0.005 and P < 0.05, respectively).

Conclusions: Postoperative ERG abnormalities and associated decreases in contrast sensitivity are consistently present in patients who have undergone nitrous oxide/sevoflurane anaesthesia. These abnormalities persist beyond the time at which standard clinical discharge criteria have been met.

Summary

Background and objective: A randomized controlled trial of patients undergoing laparoscopic cholecystectomy. To evaluate whether the instillation of levobupivacaine, with epinephrine, intraperitoneally, reduces morphine consumption; further, to consider the degree of abdominal and shoulder pain in the presence of local anaesthetic at the site of surgical incision.

Methods: Patients received a standardized procedure and were allocated randomly to receive either (a) 2.5 mg mL−1 levobupivacaine 30 mL, with epinephrine 5 μg mL−1, or (b) normal saline 30 mL, with epinephrine 5 μg mL−1, to the bed of the gall bladder and above the liver, immediately before wound closure.

Results: Median (interquartile range) total abdominal pain during inspiration in the levobupivacaine group was significantly (P = 0.041) lower (71 (21–129) mm) than that in the placebo group (123 (71–179) mm). However, there was no significant difference between the two groups with respect to total abdominal pain at rest, right shoulder pain or the consumption of rescue morphine and rescue dihydrocodeine. There were no differences between the two groups with respect to the administration of cyclizine, total nausea and total sedation scores. In addition, the number of episodes of vomiting was not significantly different.

Conclusions: Intraperitoneal administration of levobupivacaine with epinephrine is associated with modest analgesia following laparoscopic cholecystectomy.

Summary

Background and objective: Our purpose was to evaluate the analgesic and sedative effects of intrathecal midazolam when added to spinal bupivacaine in patients undergoing perianal surgery under spinal anaesthesia.

Methods: Forty-four patients were randomly allocated into two equal groups: Group I (B) received hyperbaric bupivacaine 0.5% 2 mL + saline 0.9% 1 mL in a total volume of 3 mL intrathecally; Group II (BM) received hyperbaric bupivacaine 0.5% 2 mL + 1 mL of 2 mg preservative-free midazolam in a total volume of 3 mL intrathecally. In both groups, the onset and recovery times of sensory block, the degree and recovery times of motor block as well as the sedation and visual analogue pain scores were recorded, and statistically compared.

Results: In Group BM, the postoperative visual analogue pain scores were significantly lower at the first 4 h (P < 0.05), the average time until the first dose of additional analgesic requirement was significantly longer (P < 0.05), and sedation scales were significantly higher (P < 0.05), compared to Group B. There were no statistically significant differences in the onset and the full recovery times of sensory and motor blocks in the two groups.

Conclusion: The use of intrathecal midazolam combined with intrathecal bupivacaine produces a more effective and longer analgesia with a mild sedative effect in perianal surgery.