Biomedical subjects

J van Egmond

Publications and source records attributed to J van Egmond.

At least 19 recordsLinked to original sources

PubMed2006

Time course of action of sugammadex (Org 25969) on rocuronium-induced block in the Rhesus monkey, using a simple model of equilibration of complex formation.

BACKGROUND: Reversal of neuromuscular block can be accomplished by chemical encapsulation of rocuronium by sugammadex (Org 25969), a synthetic gamma-cyclodextrin derivative. The present study determined the time course of the reversal action of sugammadex on rocuronium-induced block in the anaesthetized Rhesus monkey using train-of-four stimulation. METHODS: A bolus injection of rocuronium 100 microg kg(-1) (about 1xED(90)) was given to determine the degree of neuromuscular block reached by this dose. After complete spontaneous recovery, a rapid bolus injection of sugammadex, 1 mg kg(-1), was given and at different time intervals (15, 30 or 60 min, in three different experiments) the effect of another rocuronium bolus injection of 100 microg kg(-1) was determined. RESULTS: Injection of the first dose of rocuronium resulted in a mean neuromuscular block (depression of first twitch) of 93 (SEM=1.6)%. Fifteen minutes after injection of sugammadex the same rocuronium dose resulted in 17% (SEM=5.6) block. After 30 and 60 min these maximum blocks amounted to 49% (SEM=7.6) and 79% (SEM=4.2), respectively. The estimated half-life of sugammadex in Rhesus monkey is 30 (SEM=4.9) min. CONCLUSIONS: The half-life of sugammadex (Org 25969), a new fast and efficient reversal agent for rocuronium-induced block, is relatively short in the Rhesus monkey, implying the possibility to perform neuromuscular block by rocuronium shortly after reversal of a prior block. In translation to the human situation differences in rocuronium sensitivity and kinetics should be taken into account.

Androstanols↗

PubMed2006

An effective correlation dimension and burst suppression ratio of the EEG in rat. Correlation with sevoflurane induced anaesthetic depth.

BACKGROUND AND OBJECTIVE: Anaesthesiologists need parameters that measure the depth of anaesthesia. In the context of this need, the present study investigated in rats how two variables from the electroencephalogram, the burst suppression ratio and effective correlation dimension correlated with a measure of anaesthetic depth as measured in the strength of a noxious withdrawal reflex. METHODS: Eight rats were exposed to different inspiratory concentrations of sevoflurane, each rat in two separate experiments. In the first experiment, spontaneously breathing animals could move freely and no painful stimuli were applied. In the second experiment, in mechanically ventilated restrained anaesthetized rats, the withdrawal reflex was measured every 80 s. In both experiments the electroencephalogram was continuously recorded. The concentration in the effector compartment was estimated using a first order two compartment model. Correlation dimension was computed following the Grassberger/Procaccia/Takens approach with optimized parameter settings to achieve maximum sensitivity to anaesthetic drug effects and enable real-time computation. The Hill, equation was fitted to the data, describing the effect as a function of sevoflurane concentration. RESULTS: Good correlations of Depth of Anaesthesia with correlation dimension as well as burst suppression ratio were established in both types of experiments. Arousal by noxious stimuli decreased burst suppression ratio and increased correlation dimension. The effective sevoflurane concentration associated with 50% of the maximum effect (C50) was higher in experiment II (stimulation) than in experiment I (no stimulation): i.e. for correlation dimension 2.18% vs. 0.60% and for burst suppression ratio 3.07% vs. 1.73%. The slope factors were: gammaCD = 4.15 vs. gammaCD = 1.73 and gammaBSR = 5.2 vs. gammaBSR = 5.4. Correlation dimension and burst suppression ratio both correlated with the strength of the withdrawal reflex with correlation coefficients of 0.46 and 0.66 respectively (P < 0.001). CONCLUSIONS: Both correlation dimension and burst suppression ratio are related to anaesthetic depth and are affected by noxious stimuli. The relationship between anaesthetic depth and burst suppression ratio is confirmed and the potential of correlation dimension is demonstrated.

Anesthesia↗

PubMed2006

Sugammadex, a new reversal agent for neuromuscular block induced by rocuronium in the anaesthetized Rhesus monkey.

BACKGROUND: Binding of the steroidal molecule of rocuronium by a cyclodextrin is a new concept for reversal of neuromuscular block. The present study evaluated the ability of Sugammadex Org 25969, a synthetic gamma-cyclodextrin derivative, to reverse constant neuromuscular block of about 90% induced by rocuronium or the non-steroidal neuromuscular blocking drugs, mivacurium or atracurium, in the anaesthetized Rhesus monkey. METHODS: After a bolus injection of rocuronium, mivacurium or atracurium, a continuous infusion of these drugs was started to maintain the first twitch contraction of the train-of-four at approximately 10% of its baseline value. After a steady state block of at least 10 min the infusion was stopped and the preparation was allowed to recover spontaneously. This process was repeated, but at the time the infusion was stopped, either sugammadex 0.5 or 1.0 mg kg(-1) was given in the rocuronium-induced blockade and sugammadex 1.0 mg kg(-1) was given in the mivacurium- and atracurium-induced blockade. RESULTS: Sugammadex caused a rapid and complete reversal of rocuronium-induced neuromuscular block. The recovery time to train of four ratio=0.9 after spontaneous recovery was 14.4 min (sd=3.4 min; n=14). This was reduced significantly (P<0.001) to 3.7 min (sd=3.3 min; n=4) with sugammadex 0.5 mg kg(-1) and to 1.9 min (sd=1.0 min; n=4) with sugammadex 1.0 mg kg(-1). Signs of residual blockade or re-curarization were not observed. Reversal of mivacurium- or atracurium-induced neuromuscular block (n=2 in each experiment) by sugammadex (1.0 mg kg(-1)) was not effective. In all experiments, injection of sugammadex had no effects on blood pressure or heart rate. CONCLUSIONS: Sugammadex is effective in reversing rocuronium, but not mivacurium- or atracurium-induced neuromuscular block.

Androstanols↗

PubMed2006

Do diagnostic segmental nerve root blocks in chronic low back pain patients with radiation to the leg lack distinct sensory effects? A preliminary study.

BACKGROUND: The present preliminary study documents the effects of a selective nerve root block (SNB) with short or long acting local anaesthetic compared with baseline measurements in patients with chronic low back pain radiating to the leg with maximum pain in one dermatome (L4). METHODS: Ten consecutive patients underwent 20 controlled SNBs at L4 with ropivacaine 0.25% and lidocaine 1% in a prospective, randomized, double blind, crossover fashion. Baseline measurements included sensory function (assessed by pinprick on both unaffected and painful leg) and pain (Verbal Numeric Rating Scale; VNRS, 0-10). A change in size of areas with altered sensory function >10% and a VNRS change of 2 points were considered clinically significant. P-values<0.05 were considered statistically significant. RESULTS: Asymptomatic hypoaesthesia, variable in extent and non-dermatomal in distribution, was present in seven patients at baseline. It appeared to be more extensive and distal with longer duration of pre-existing pain. SNB produced no consistent changes in extent and distribution of hypoaesthetic areas. Change in VNRS did not correlate with the extent of pre-block or post-block hypoaesthesia. No differences in effects were found between lidocaine and ropivacaine. CONCLUSIONS: Pre-block assessment of sensory function is essential to assess the net effect of SNBs. In this small study group, SNBs failed to demonstrate uniform or distinct effects on sensory function.

Adult↗

PubMed2006

Depth of the thoracic epidural space in children.

Thoracic epidural anaesthesia in anaesthetized children requires a meticulous technique and may have an increased success rate when the distance between skin and epidural space is known. The objective of this observational study was to measure the skin to epidural distance (SED) during thoracic epidural puncture in 61 children. The epidural puncture was performed using the loss of resistance technique with saline 0.9%. The distance from the needle tip to the point where the needle emerged from the skin was measured. The post-operative analgesia parameters were also measured. Skin to epidural distance correlated significantly with the age and weight of the children. The equation for the relation between SED (cm) and age was 2.15 + (0.01 x months) and for SED vs weight was 1.95 + (0.045 x kg). Despite considerable variability among individuals, the observed correlation of SED with both age and weight shows that this parameter may be helpful to guide thoracic epidural puncture in anaesthetized children.

Adolescent↗

PubMed2005

Chemical encapsulation of rocuronium by synthetic cyclodextrin derivatives: reversal of neuromuscular block in anaesthetized Rhesus monkeys.

BACKGROUND: At present, reversal of neuromuscular block induced by steroidal neuromuscular blocking agents (NMBAs) is achieved by administration of cholinesterase inhibitors. Chemical encapsulation of steroidal NMBAs, such as rocuronium, by a cyclodextrin is a new concept in neuromuscular block reversal. The present study evaluates the capacity of nine synthetic cyclodextrin derivatives (Org 25288, Org 25289, Org 25467, Org 25168, Org 25169, Org 25555, Org 25166, Org 26142, and Org 25969) to reverse constant neuromuscular block of approximately 90%, induced by rocuronium infusion in the Rhesus monkey, using single twitch stimulation. The ability of these cyclodextrin derivatives to reverse neuromuscular block was compared with the reversal of the same neuromuscular block by the commonly used combination of neostigmine and atropine. METHODS: After a bolus injection of rocuronium, continuous infusion was started to reduce twitch contractions to approximately 10% of baseline values. After a steady state block of at least 10 min the infusion was stopped and the preparation was allowed to recover spontaneously. This process was repeated, but at the time the infusion was stopped, either one of the nine cyclodextrin derivatives or a combination of neostigmine and atropine was given. RESULTS: Recovery with cyclodextrin derivatives Org 26142 and Org 25969 was faster than after a combination of neostigmine and atropine (P<0.05). Injection of these cyclodextrin derivatives did not affect blood pressure or heart rate. Signs of residual block or recurarization were not observed in any of these experiments. In the experiments in which a combination of neostigmine and atropine was given, two animals showed signs of abdominal discomfort as frequently seen after the administration of neostigmine and significant changes in circulatory variables. CONCLUSIONS: Chemical encapsulation or chelation of rocuronium is a new concept in reversing neuromuscular block induced by rocuronium.

Androstanols↗

PubMed2003

Electromyographic assessment of blink and corneal reflexes during midazolam administration: useful methods for assessing depth of anesthesia?

BACKGROUND: There are at least three components of the anesthetic state: loss of consciousness, amnesia and obtundation of reflex responses to noxious stimuli. To investigate the third component, we used a standard electrical stimulus to evoke a blink reflex, which was electromyographically recorded. These data may give information on the anesthetic state. METHODS: The relation between the electrically evoked blink and corneal reflexes and the depth of sedation and anesthesia induced with intravenous midazolam was investigated. Ten patients received i.v. increments of midazolam (1 mg, 2 mg, 3 mg, 3 mg, 3 mg, etc., until a 21-mg total dose) to create a step-wise deepening of sedation and anesthesia. Depth of anesthesia was assessed by the Observer's Assessment of Alertness/Sedation (OAAS) scale, ranging from 5 ( = awake and alert) to 0 ( = no motor response to tetanic stimulation). RESULTS: Latency of the first (R1) and second (R2) blink components and the corneal (C) reflex component increased, whereas duration and area decreased with increasing depth of sedation and anesthesia. R1 was last seen at an OAAS score [mean (SD)] of 1.8 (0.8), R2 at a score of 3.1 (1.1), C at a score of 3.8 (0.8), and R3 at 4.8 (0.5). These end-points were all statistically different from each other, except R2 vs. C. CONCLUSIONS: Our results suggest that the differential sensitivity of the components of the blink reflex could be useful to monitor depth of sedation and light levels of anesthesia during the administration of midazolam.

Adult↗

PubMed2002

A blind spot for secondary gain affecting therapy outcomes.

BACKGROUND: A study to determine whether the expectation for secondary gain held by psychiatric outpatients was associated with therapy outcomes. METHODS: The study was conducted at a Dutch psychiatric outpatient department. Our investigation set out to explore the expectation of obtaining secondary gain by directly asking the patient and clinician via questionnaires whether the patient anticipated to get specific "benefits" from being in therapy. RESULTS: From 166 patients, 70 (42.2%) reported to expect secondary gain while in therapy. We found a significant relation between expectation for secondary gain and treatment outcomes. Patients with expectations for secondary gain were significantly more prone to poor therapy outcome. Only in nine of 147 cases (6%) did patients explicitly express their expectations for secondary gain towards a psychiatrist. Moreover, expectations for secondary gain did not appear to be related to Axis I and Axis II diagnoses. DISCUSSION: Secondary gain appeared to be a "veiled motive" for getting therapy: patients did not express their expectations for secondary gain explicitly towards a psychiatrist. This aspect of veiled motives is of particular relevance in regard to the fact that expectations for secondary gain appeared to affect therapy results.

Adolescent↗

PubMed2000

Non-depolarizing neuromuscular blocking activity of bisquaternary amino di- and tripeptide derivatives.

Herein we describe the synthesis of novel di- and tripeptide derivatives with two quaternary nitrogen groups attached and the biological testing of these compounds for neuromuscular blocking (NMB) activity in vitro and in vivo. The short peptide scaffold was selected because it offers potential for desired distance between the two pharmacophoric quaternary nitrogen groups, short duration of action, straightforward synthesis, and compatibility with an injectable formulation. From a small series of compounds 20c,e are identified as effective non-depolarizing NMB agents in vitro and in vivo in anesthetized cats and Rhesus monkeys with potencies similar to those of the clinical reference compounds rocuronium (4) and suxamethonium (2) (monkey ED(90) = 0.68, 0.23, 0.16, 5.04 micromol/kg, respectively). These new peptide derivatives 20c,e have similar potency and onset time but longer duration and slower recovery than the clinically used reference compounds. The structure-activity relationships described for this chemical series lead to the conclusion that the di- or tripeptide fragment can be regarded as an alternative template to the steroid or aliphatic ester of previously reported NMBs and within this tripeptide-derived series clog P correlates well with in vitro NMB activity.

Amines↗

PubMed2000

The influence of diazepam on the electroencephalogram-evoked potential interrelation in rats.

Though being a sedative, diazepam increases beta-activity in the electroencephalogram (EEG). Diazepam also affects auditory evoked potentials (AEPs). We investigated if the effect of diazepam on AEPs could be ascribed to its beta-increasing effect. Eight rats received vehicle and diazepam counterbalanced. AEPs were ranked in ten categories according to the percentages of beta-activity in the pre-stimulus electroencephalogram (EEG). With vehicle, the P(29), N(51) and P(67) AEP components increased and cross-correlation coefficients (CCCs) declined with increasing beta-activity. With diazepam AEP components and CCCs remained unchanged. All AEPs with diazepam closely resembled the AEP of the lowest beta-category obtained with vehicle. We conclude that the effect of diazepam on AEPs can not be ascribed to its beta-enhancing effect. Diazepam disrupts the normal AEP-EEG relation such that diazepam-effects on AEPs seem to reflect the sedative effects of diazepam and not its beta-increasing effects.

Animals↗

PubMed2000

Contractures in skeletal muscle of malignant hyperthermia susceptible patients after in vitro exposure to sevoflurane.

BACKGROUND: Sevoflurane, a potent inhalational anaesthetic agent that is structurally similar to halothane, has some favourable characteristics, but may also be able to trigger malignant hyperthermia (MH) in susceptible patients. The diagnosis of malignant hyperthermia susceptibility relies on the in vitro contracture test on skeletal muscle. The present study was undertaken to investigate whether exposure to sevoflurane of muscles of malignant hyperthermia susceptible (MHS) patients would also cause an abnormal contracture. METHODS: Muscle fascicles obtained from three MHS patients, one malignant hyperthermia non-susceptible (MHN) patient, two control patients and one malignant hyperthermia equivocal (MHE) patient were exposed to sevoflurane instead of halothane in the in vitro contracture test, carried out according to the protocol of the European Malignant Hyperthermia Group. The muscle fascicles were surplus to diagnostic requirements. Sevoflurane concentrations in the testbath were measured using a headspace gas chromatographic technique. RESULTS: The kinetics of sevoflurane concentration in the testbath were similar to those of halothane. An in vitro contracture response of 2 mN or more was seen in all four MHS/MHE patients with sevoflurane but not in the three control/MHN patients. The magnitude of muscle contracture in the sevoflurane test was less than in the conventional halothane test at comparable testbath concentrations. CONCLUSIONS: Sevoflurane can trigger an abnormal contracture in human muscle in vitro. This is indicative of malignant hyperthermia susceptibility. Exposure to sevoflurane should be avoided in patients thought to be susceptible to malignant hyperthermia.

Anesthetics, Inhalation↗

PubMed2000

Elevated detection thresholds for mechanical stimuli in chronic pain patients: support for a central mechanism.

OBJECTIVE: To investigate the relation between pain provoking cervical segments identified by diagnostic dorsal root blockades and elevation of detection thresholds in patients suffering from chronic cervicobrachialgia (CCB). DESIGN: Quantitative sensory testing (light touch) of the cervical dermatomes using Semmes-Weinstein monofilaments. SETTING: A university pain clinic. SUBJECTS: Thirty-nine patients with CCB, with no clinical or diagnostic evidence of radiculopathy or surgically treatable bony lesion and with one main pain-provoking cervical segment identified by diagnostic dorsal root blockades. OUTCOME MEASURES: Detection thresholds with 95% confidence intervals (95% CI) of pain-provoking segments, compared with surrounding and contralateral segments and with normal values for cervical dermatomes. RESULTS: Patients' detection thresholds were significantly (p < .001) higher than those for normal subjects: 3.51 (95% CI, 2.71-4.31) and 3.10 (95% CI, 2.34-3.86), respectively. No significant differences existed between the segments. The elevations were systematic. However, thresholds on the painful side were consistently, slightly higher than those on the contralateral side. CONCLUSION: Supporting earlier studies, results from CCB patients in the present study showed systematic elevation of detection thresholds (low threshold mechanoreceptors), an adaptation in contrast with, but not contradictory to, central sensitization of high threshold neurons in chronic pain.

Adaptation, Physiological↗

PubMed2000

Correlation dimension of the human electroencephalogram corresponds with cognitive load.

This study aimed at assessing the effects of cognitive activity and mental task load on the correlation dimension of the human electroencephalogram (EEG). Three experimental conditions were created: a baseline condition and two cognitive task conditions, a calculation task and a time estimation task. The calculation task was supposed to induce a higher mental load than the time estimation task, which is regarded as a less complex one. This was verified by a subjective rating scale. All conditions differed significantly in subjective estimated task load. The correlation dimension appeared to be higher in both task conditions compared to the baseline condition. A comparison of the two tasks indicated that the difference in correlation dimension between calculation and time estimation was also significant, with the highest value for calculation. It is concluded that cognitive and mental activity is associated with a higher correlation dimension in the EEG. This implies that the correlation dimension is a sensitive parameter in the analysis of electrical brain activity.

Adult↗

PubMed1999

Evaluation of the electroencephalographic bispectral index during fentanyl-midazolam anaesthesia for cardiac surgery. Does it predict haemodynamic responses during endotracheal intubation and sternotomy?

The bispectral index, a value derived from the electroencephalogram, has been proposed as a measure of anaesthetic effect. The aim of the present study was to evaluate the bispectral index during midazolam-fentanyl anaesthesia for cardiac surgery for its possible role as a predictor of increases in systolic blood pressure during endotracheal intubation and sternotomy. After institutional approval 15 consenting patients, scheduled for elective cardiac surgery, were selected for the study. Anaesthesia was induced in all patients with a loading dose of fentanyl 7.5-10 micrograms kg-1, midazolam 0.15 mg kg-1 and pancuronium 0.1 mg kg-1. After a further bolus dose of fentanyl 10-12.5 micrograms kg-1 prior to the start of incision and sternotomy, maintenance infusion rates of fentanyl 4-6 micrograms kg-1 h-1 and midazolam 0.1 mg kg-1 h-1 were started and continued through surgery at the discretion of the anaesthetist and guided by the presenting clinical and haemodynamic responses. The control of anaesthesia was never based on the value of the bispectral index. The mean bispectral index value decreased from 95.7 (3.1) at base-line to 59.5 (12.0) after induction of anaesthesia and then remained below 70 throughout surgery. However, there was an important interindividual variability in bispectral index values despite standardized dosages of fentanyl and midazolam. There was no significant correlation between the bispectral index values in the pre-intubation and pre-incision period and the changes in systolic blood pressure during endotracheal intubation and sternotomy, respectively. In conclusion, the large intersubject variability in the bispectral index values should be investigated further in the light of the great variability in the clinical effects of midazolam and fentanyl. The lack of significant correlation between the bispectral index values and the haemodynamic responses suggest that the bispectral index, which is a helpful monitor of anaesthetic depth, is not a very reliable monitor of global anaesthetic adequacy during total intravenous anaesthesia with a combination of midazolam and fentanyl in cardiac surgical patients.

Adjuvants, Anesthesia↗

PubMed1999

Intrathecal coadministration of bupivacaine diminishes morphine dose progression during long-term intrathecal infusion in cancer patients.

OBJECTIVE: To determine the difference in intrathecal morphine dose progression between a continuous intrathecal infusion of a morphine/bupivacaine mixture and morphine for pain relief in patients with cancer. DESIGN: Patients were treated with intrathecal drugs in a randomized study and followed prospectively until death. SETTING: Institute for Anesthesiology, Department of Pain Treatment, University Hospital Nijmegen, St Radboud, The Netherlands. PATIENTS: Twenty patients with cancer were selected for intrathecal treatment because of either side effects or inadequate relief during conventional pain treatment. INTERVENTIONS: Intrathecal drug infusion rates and medication were adjusted according to pain relief and side effects. OUTCOME MEASURES: Progression of intrathecal morphine dose during a phase of adequate analgesia in both groups following regression analysis and analysis of possible treatment related side effects. RESULTS: The combination of intrathecal morphine and bupivacaine resulted in a diminished progression of the intrathecal morphine dose (slope of regression line = 0.0003 vs. 0.005, p = 0.0001) during a phase of stable analgesia in comparison with the morphine group. No serious side effects presented. CONCLUSION: The diminished intrathecal morphine dose increase in the combination group is considered to be due to a synergistic effect of bupivacaine on the intrathecal morphine-induced antinociception. A dose increment during long-term intrathecal infusion in cancer patients appears to be related to both disease progression and tolerance phenomena.

Adult↗

PubMed1999

Effects of polytherapy compared with monotherapy in antiepileptic drugs: an animal study.

Although monotherapy in epilepsy treatment is frequently advocated, this is not based on studies with equal drug loads. This study was performed to investigate the experimental background of polytherapy with standardized drug loads. Dose-dependent effects on grip strength, accelerod performance, and spontaneous behavior of rats was used to study the effect of combining valproate and ethosuximide. The potency of the drugs (combination) was obtained by fitting the sigmoid Emax equation to the data. Drug interaction was assessed using the isobologram method and quantified by comparing equivalent drug loads with their 95% confidence intervals. We found that the effects of valproate and ethosuximide combine in a simple additive way in the grip strength experiment as well as in the accelerod experiment. In the behavioral studies, however, a higher drug load of the combination was needed to obtain the same amount of sedation, signifying infra-additivity. Infra-additivity of sedative effects is an important finding because this is by far the most frequent side effect mentioned in human studies. However, assessment of the therapeutic effect of the combination will have to be completed before a preference for mono- or polytherapy, based on the balance of adverse effects and efficacy, can be expressed.

Animals↗

PubMed1998

Extension of sensory blockade after thoracic epidural administration of a test dose of lidocaine at three different levels.

UNLABELLED: To evaluate the relationship between the level of thoracic epidural injection and the extension of sensory blockade, we inserted radiopaque epidural catheters in 87 patients at the high (C7-T2, n = 28), mid (T3-5, n = 29) or low (T7-9, n = 30) thoracic levels. Fifteen minutes after the epidural administration of 60 mg of lidocaine, the mean (+/- SD) sensory block extension varied from 5.4 +/- 3.1 to 7.7 +/- 1.8 segments. The level of epidural puncture was a statistically significant factor in determining the cranial and caudal borders of sensory blockade (P = 0.0001, analysis of variance), but in determining for the total number of segments blocked. The number of blocked dermatomes located cranially of the puncture level increased significantly with descending injection site (P = 0.0001). We acquired chest radiographs in 61 patients to determine epidural catheter tip position. Direction of the epidural catheter tip was not a significant factor in determining the extension or borders of sensory blockade. We conclude that the extension of sensory blockade in thoracic epidural anesthesia is not influenced by the level of epidural puncture or catheter tip direction. There is, however, a more cranial spread of sensory blockade in the low thoracic region compared with the high thoracic region. IMPLICATIONS: After evaluating the extension and pattern of sensory blockade in high, mid, and low thoracic epidural analgesia, the authors suggest that it is safe to use similar dosage regimens in all three regions, and that in high thoracic epidural analgesia, it is important to insert the epidural catheter at the level of the intended cranial border of blockade.

Adult↗

PubMed1997

Monitoring during cryosurgery of bone tumors.

BACKGROUND: Cryosurgery is used in orthopaedic oncology as adjuvant treatment after intralesional excision of bone tumors to induce cell death at and beyond the surgical margin. Monitoring freeze/thaw cycles during cryosurgery is beneficial in controlling a cryosurgical procedure and in preventing an unwarranted local extent of the freeze. METHOD: We conducted a study of 15 cryosurgical procedures with the use of a protocolized temperature measuring system wit peroperative graphic visualization. RESULTS: Using a liquid nitrogen spray, intralesional temperatures of -150 degrees C were achieved, which are, according to the literature, associated with cell death. Extralesional temperature measurements showed no sub-zero temperatures of surrounding important tissues. CONCLUSIONS: Temperature recordings in and outside the lesion during cryosurgery in orthopaedic oncology are of importance to monitor the freeze/thaw cycles and are helpful in facilitating an effective cryosurgical procedure and in controlling the extent of the freeze, avoiding local complications.

Adolescent↗