A. van Zundert

Long-lasting Epidural Sensory Blockade by n-Butyl-p-Aminobenzoate in the Terminally Ill Intractable Cancer Pain Patient

An aqueous suspension of n-butyl-p-aminobenzoate (BAB), a highly lipid-soluble congener of benzocaine, was applied epidurally in terminally ill cancer patients with intractable pain. The suspension consisted of 10% BAB and 0.025% of the nonionic surfactant polysorbate 80 in 0.9% sodium chloride. Twelve consecutive patients received epidural BAB because pain was uncontrollable either by palliative radiotherapy or oral or epidural administrations of analgesics. The catheter or injecting needle was positioned at the segmental level of the pain. Repeated epidural injections were administered. In all patients, long-lasting sensory blockade (segmental analgesia) occurred, accompanied by a marked reduction or even absence of pain. In all patients, treatment with epidural opioids, alone or combined with local anesthetics, was no longer necessary. Five of the 12 patients did not require further administration of oral opioids. Motor, bowel, and bladder function were well preserved. In 6 patients, extensive necropsy of the spinal cord and spinal nerves did not reveal pathomorphologic changes. The outer aspect of the dura showed signs of focal necrosis on microscopy, yet its collagen structure and thickness were unchanged. Epidurally, focal infiltrative reactions were seen. The epidural use of an extremely lipid-soluble--hence hydrophobic--local anesthetic, with an exceptionally low pKa (2.3), formulated in suspension of the base, is conceptually innovative and needs further investigation. The authors conclude that the epidural administration of a BAB suspension may be an effective alternative to the neurolytic agents alcohol and phenol and may replace procedures such as cordotomy. Further investigation to determine the safety of BAB in this patient group appears warranted.

Comparison of cuff-pressure changes in Lma-classic® and the new Soft Seal® laryngeal masks during nitrous oxide anaesthesia in spontaneous breathing patients

Background and objective: There are concerns over the intra-cuff pressure of the laryngeal mask and laryngo-pharyngeal morbidity. In a randomized study, the authors compared cuff-pressure changes in the LMA-Classic® and the new disposable Soft Seal® laryngeal mask during nitrous oxide anaesthesia. Methods: Two-hundred adult patients were randomly assigned to a size 4 laryngeal mask in two equal-sized groups for airway management: (a) the re-usable LMA-Classic®, or (b) the new disposable Soft Seal® laryngeal mask. Anaesthesia was administered with fentanyl, propofol, nitrous oxide, O2 and sevoflurane. The cuff pressures, adjusted to 45 mmHg at insertion, were monitored continuously until the end of the operation without any further attempt to reduce cuff pressure. On removal of the laryngeal mask, any blood at all was considered positive. Patients were requested to report any sore throat at 2 and 24 h postoperatively. Results: During nitrous oxide anaesthesia, cuff pressures increased in the LMA-Classic® group from 45 to 100.3 mmHg and from 45 to 46.8 mmHg in the Soft Seal® laryngeal mask group (P < 0.001). The incidence of sore throat was significantly higher at 2 h postoperatively when using the LMA-Classic®, although there was no difference at 24 h following the operation. Macroscopic blood was only seen on four occasions in the LMA-Classic® group (not significant). Conclusions: During nitrous oxide anaesthesia, cuff pressure increases in the LMA-Classic® mask were significantly higher than those of the Soft Seal® laryngeal mask. Trauma to patients, as assessed by the incidence of sore throat in the early postoperative period was significantly higher in the LMA-Classic® group. Cuff pressures should be monitored during nitrous oxide anaesthesia when LMA-Classic® is used but to do so is of less importance when using the disposable Soft Seal® laryngeal mask.

Extent of anesthesia and hemodynamic effects after subarachnoid administration of bupivacaine with epinephrine

It has been suggested that the amount of local anesthetic injected into the subarachnoid space is more important than the volume or concentration that is used in determining the extent of anesthesia (1-7). However, this conclusion was based on studies using small volumes of local anesthetic (e.g., 1 4 ml). We have used larger volumes of local anesthetic (10 ml) for subarachnoid anesthesia, with good analgesia and without complications (8). We have now evaluated the effect of using widely disparate volumes (2.5 vs 10 ml) and concentrations (0.5% vs 0.125%) of bupivacaine while maintaining a constant dose (12.5 mg) on the extent of sensory anesthesia and the resultant hemodynamic changes.

Long-lasting Epidural Sensory Blockade by n-Butyl p-Aminobenzoate in the Dog: Neurotoxic or Local Anesthetic Effect?

An aqueous suspension of n-butyl p-aminobenzoate (BAB), a highly lipid-soluble congener of benzocaine, was applied epidurally and around ulnar nerves in dogs. The suspension consisted of 10% BAB and 0.025% polysorbate in 0.9% NaCl. Sensory effects were tested by electrical stimulation. Three epidural injections were given, and the dogs were killed after 21 days. The increase in stimulation threshold was comparable to the effect of lidocaine in a concentration between 0.5% and 1%. Increased sensory threshold lasted for days, whereas no long-lasting motor effects were observed. Pathomorphologic changes were found primarily in the dorsal spinal nerve roots, although slight changes were also found in the ventral spinal roots. White matter degeneration was found only in the lumbar dorsal columns. This result suggested Wallerian degeneration in the dorsal spinal nerves and was at variance with recently published data on epidural BAB. No changes were observed in the ulnar nerves. The authors demonstrated that the pathomorphologic changes were induced by the BAB suspension and not by the suspending additive polysorbate 80. It was postulated that the suspension of BAB, which contains particles of a median size of 15 microns, was mainly confined to the dorsal epidural space where neurolytic changes in axons of the dorsal spinal nerve roots and dorsal columns are induced. This may explain the long-lasting sensory effects seen in intractable cancer pain patients after epidural BAB administration. More research is necessary to define the distribution of BAB in nervous tissue after its epidural administration and to better characterize toxicity, neurolytic effects, and regeneration of nervous tissue after BAB administrations.

The LMA-SupremeTM as an intubation conduit in patients with known difficult airways: a prospective evaluation study

Many extraglottic airway devices allow the direct passage of an adult‐sized tracheal tube, but this is not possible with the LMA‐SupremeTM. We evaluated the feasibility of using the LMA‐SupremeTM as a conduit for intubation in patients with known difficult airways.

Combined technique using videolaryngoscopy and Bonfils for a difficult airway intubation

tically significant differences in heart rate, arterial pressure, anaesthetic vapour concentration, haematocrit, phenylephrine dosing, or the partial pressure of carbon dioxide in arterial blood between the measurement points. The results of the study demonstrate that cerebral oxygenation varies directly with FIO2 in anaesthetized patients with severe carotid artery stenosis. The observed increase in rSO2 was similar to that reported in anaesthetized ventilated patients without vascular disease and in anaesthetized patients after the placement of a carotid cross-clamp. Contrary to previous reports, we did not observe a relationship in the degree of carotid artery stenosis and rSO2 between hemispheres. Recent evidence suggests that bolus-dose phenylephrine is associated with a measureable decrease in rSO2 of 7–8 min duration. 6 Here there was no difference in phenylephrine dosing between the groups. The effect of phenylephrine by infusion has yet to be investigated. Although the clinical significance of an 8% increase in rSO2 remains to be determined, the results provide a rationale to increase FIO2 in ventilated patients with severe carotid artery disease and illustrate that measurement of cerebral oxygenation by NIRS may be helpful for such patients undergoing non-vascular surgical procedures. Increasing FIO2 may be especially helpful during periods of increased neurological risk such as hypotension and anaemia or if surgical positioning is likely to impede cerebral blood flow. The adverse consequences of ventilating patients with 100% O2 for relatively short periods are likely to be limited.

Which method of estimating renal function is the best predictor of mortality after coronary artery bypass grafting

ObjectivesDefinitions of renal function in patients undergoing coronary artery bypass graft surgery (CABG) vary in the literature. We sought to investigate which method of estimating renal function is the best predictor of mortality after CABG.MethodsWe analysed the preoperative and postoperative renal function data from all patients undergoing isolated CABG from January 1998 through December 2007. Preoperative and postoperative renal function was estimated using serum creatinine (SeCr) levels, creatinine clearance (CrCl) determined by the Cockcroft-Gault formula and the glomerular filtration rate (e-GFR) estimated by the Modification of Diet in Renal Disease (MDRD) formula. Receiver operator characteristic (ROC) curves and area under the ROC curves were calculated.ResultsIn 9987 patients, CrCl had the best discriminatory power to predict early as well as late mortality, followed by e-GFR and finally SeCr. The odds ratios for preoperative parameters for early mortality were closer to 1 than those of the postoperative parameters.ConclusionsRenal function determined by the Cockcroft-Gault formula is the best predictor of early and late mortality after CABG. The relationship between renal function and mortality is non-linear. Renal function as a variable in risk scoring systems such as the EuroSCORE needs to be reconsidered.

Evaluation of the EuroSCORE risk scoring model for patients undergoing coronary artery bypass graft surgery: a word of caution

Background. Risk-adjusted mortality rates are used to compare quality of care of different hospitals. We evaluated the EuroSCORE (European System for Cardiac Operative Risk Evaluation) in patients undergoing isolated coronary artery bypass grafting (CABG).Patients and method. Data of all CABG patients from January 2004 until December 2008 were analysed. Receiver-operating characteristics (ROC) curves for the additive and logistic EuroSCOREs and the areas under the ROC curve were calculated. Predicted probability of hospital mortality was calculated using logistic regression analyses and compared with the EuroSCORE. Cumulative sum (CUSUM) analyses were performed for the EuroSCORE and the actual hospital mortality.Results. 5249 patients underwent CABG of which 89 (1.7%) died. The mean additive EuroSCORE was 3.5±2.5 (0-17) (median 3.0) and the mean logistic EuroSCORE was 4.0±5.5 (0-73) (median 2.4). The area under the ROC curve was 0.80±0.02 (95% confidence interval (CI) 0.76 to 0.84) for the additive and 0.81±0.02 (0.77 to 0.85) for the logistic EuroSCORE. The predicted probability (hazard ratio) was different from the additive and logistic EuroSCOREs. The hospital mortality was half of the EuroSCOREs, resulting in positive variable life-adjusted display curves. Conclusions. Both the additive and logistic EuroSCOREs are overestimating the in-hospital mortality risk in low-risk CABG patients. The logistic EuroSCORE is more accurate in high-risk patients compared with the additive EuroSCORE. Until a more accurate risk scoring system is available, we suggest being careful when comparing the quality of care of different centres based on risk-adjusted mortality rates. (Neth Heart J 2010;18:355-9.)

Anaesthesia for advanced rectal cancer patients treated with combined major resections and intraoperative radiotherapy

Background and objective: Multimodality treatment for patients with locally advanced primary or locally recurrent rectal cancer, including high-dose preoperative external beam radiotherapy, extensive surgery and intraoperative radiation therapy, decreases the local recurrence rates and improves survival. During this aggressive operation, the anaesthesiologist is faced with potential problems such as major transfusion requirements, hypothermia, intraoperative position changes, the need to transport the patient to the intraoperative radiation therapy applicator, and the risks associated with remote monitoring of the patient during the 10 min intraoperative radiation therapy application. The anaesthetic management and perioperative results were evaluated for the anaesthetic results and the complications. Methods: One-hundred-and-six patients undergoing the multimodality treatment between February 1994 and March 2000 for locally advanced primary (n = 50) and locally recurrent rectal cancer (n = 56) were retrospectively evaluated for their anaesthetic results and complications. Results: All patients were operated upon using a combination of general and epidural anaesthesia. The average duration of anaesthesia was 6 (range 3-10.5) h and the mean blood loss 3.6 (range 0.4-14) L. All patients recovered well from anaesthesia. Two patients (2%) died in the intensive care unit (34 and 48 days postoperatively) because of adult respiratory distress syndrome following postoperative haemorrhage. Severe haemorrhage during or after the operation was significantly related with the development of adult respiratory distress syndrome (P < 0.0001). Conclusions: With adequate preoperative assessment and optimalization of the patients condition, maintaining peroperative haemodynamic stability with the help of adequate remote monitoring, early and fast transfusion, and multidisciplinary communication, anaesthetic complications can be minimized.

ARE BREECH DELIVERIES AN INDICATION FOR LUMBAR EPIDURAL ANALGESIA

Lumbar epidural analgesia (LEA) for pain relief in labor and delivery is still considered to reduce expulsion forces, thereby prolonging the second stage of labor and increasing the number of instrumental deliveries ( 1 4 ) . The second stage of labor has been regarded as a time of particular risk for the development of fetal hypoxia, as reflected by the progressive deterioration in acid-base status of the fetus during the expulsion phase (5). The duration of the second stage of labor also adversely affects the neonatal acid-base balance (6,7). Kalinkov et al. (8) found that expulsion phases lasting more than 2C-30 min produce metabolic acidosis due to production of lactate during maternal straining. Labor with a second stage lasting longer than 120 min is associated with increased perinatal mortality (9-11). All the above is of special concern in breech deliveries to such an extent that some obstetricians hesitate and even refuse to use LEA for breech deliveries (12-15). In an earlier study, we demonstrated in 877 singleton vertex deliveries that an LEA technique using 0.125% bupivacaine plus epinephrine 1:800,000 led to a mean expulsion time of 6.80 2 0.15 min (16). In our institution, vaginal breech deliveries are considered by the obstetricians as a strong indication for LEA. In this survey, we studied the duration of the second stage, the expulsion times (ETs), the