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PubMed1990

The effects of intraoperative hypothermia and cardiopulmonary bypass on trace metals and their protein binding ratios.

The ability of intraoperative hypothermia to modify the metabolic response to cardiopulmonary bypass (CPB) was assessed by serial alterations in iron, zinc and copper, and in their molar binding ratios to their respective transport proteins, in 20 male patients under-going elective coronary artery surgery and randomised to an operative blood temperature of 28 degrees C or 20 degrees C. Decreases in serum iron and zinc concentrations, typical of the acute phase response, were preceded by early rises. Significant alterations in the metal: protein molar binding ratios preceded significant changes in the serum concentrations of the metals and occurred earliest in the zinc: albumin binding ratio, which was apparent by the time of skin incision. An intraoperative temperature of 20 degrees C modified iron and zinc concentrations and their protein binding ratios during surgery but not in the post-operative period. These early changes in trace metals and their protein binding ratios are a simple and inexpensive method of quantitating the response to surgical injury and may be useful in assessing new interventions in cardiopulmonary bypass. An awareness of the trace element response to surgical injury is essential to avoid misdiagnoses of iron deficiency anaemia or zinc deficiency.

Adult↗

PubMed1997

Event-related potential measures of information processing during general anesthesia.

To investigate the incidence and manner of auditory information processing during a state of presumed unconsciousness event-related brain potentials (ERPs) were studied in 41 patients undergoing cardiac surgery with propofol/alfentanil anesthesia. The ERPs were recorded during auditory oddball tasks administered before and within several periods of the operation. Mean nasopharyngeal temperature and anesthetic concentrations were determined for each intraoperative ERP recording epoch. During anesthesia ERP waves could still be observed up to 500 ms after stimulus onset indicating that auditory information processing was not suppressed completely by the administered anesthetic agents. Relative to the preoperative recordings, the P1-N1-P2 complex was delayed and more positive going during anesthesia. Comparable changes in ERP morphology have been observed during Stage II-IV sleep, suggesting parallels in the mechanisms underlying early auditory processing in both states of reduced arousal level, possibly related to a selective reduction of a non-specific activity. N1 and P2 peak amplitudes were found to be larger for the deviant tones compared to the standard tones. These amplitude differences most likely reflect automatic detection of stimulus deviance, although it cannot be excluded entirely that they were due to differences in refractoriness. Anesthetic concentrations and nasopharyngeal temperature were found to be of minor significance for ERP control. It is suggested that ERPs could serve as intraoperative reference measures, providing the earliest evidence for auditory processing. This characteristic is important for validation of signals and techniques that are proposed to improve conventional monitoring of anesthesia with respect to detecting unintended awareness.

Adult↗

PubMed2003

Different benefit of bispectal index (BIS) in desflurane and propofol anesthesia.

BACKGROUND: Bispectal index (BIS) monitoring may reduce drug usage and hasten recovery in propofol and inhalation anesthesia. The faster emergence profile of desflurane may reduce the effect of BIS monitoring on recovery from desflurane compared with propofol. This study compared hypnotic drug usage, recovery, patient satisfaction and incidence of inadequate sedation in BIS monitored and nonmonitored women anesthetized with desflurane or propofol. METHODS: One hundred and sixty patients scheduled for elective gynecological surgery were randomly assigned to desflurane or propofol anesthesia with and without BIS monitoring. Fentanyl, vecuronium and remifentanil were administered according to clinical criteria. The BIS monitor was used in all patients, but the monitor screen was covered in the controls. A BIS level between 45 and 55 was targeted in the BIS monitored patients whereas depth of anesthesia was assessed by clinical criteria in the controls. RESULTS: The mean (SD) desflurane MAC-hours administered with and without BIS were 0.70 (0.15) and 0.76 (0.12), respectively, resulting in extubation times of 6.5 (4.1) and 8.3 (6.1) min. (NS). Bispectal index monitoring was associated with improved patient satisfaction, reduced postoperative nausea and antiemetic drug requirement, and fewer episodes with sustained BIS levels > 60. The mean (SD) propofol infusion rates were 6.0 (1.4) and 6.6 (0.9) mg kg(-1)h(-1) with and without the BIS monitor (P = 0.023), resulting in mean (SD) extubation times of 6.8 (4.6) and 10.5 min (5.9), respectively (P < 0.05). CONCLUSION: Bispectal index monitoring reduced propofol usage and hastened recovery after propofol anesthesia, whereas in desflurane anesthesia it was associated with improved patient satisfaction, probably because of decreased postoperative nausea and fewer episodes of inadequate hypnosis.

Adult↗

PubMed1998

Limited value of preoperative cervical vascular imaging in patients with velocardiofacial syndrome.

The purpose of this two-part study was to evaluate the safety of surgical management of speech production disorders in patients with velocardiofacial syndrome without preoperative cervical vascular imaging studies. Anomalous internal carotid arteries have been shown to be a frequent feature of velocardiofacial syndrome. These vessels pose a potential risk for hemorrhage during velopharyngeal narrowing procedures. Magnetic resonance angiography, and other forms of cervical vascular imaging studies such as computerized tomography, have been advocated as aids to surgery by defining the preoperative vascular anatomy. However, it remains unclear whether these studies alter either the conduct or outcome of operations on the velopharynx. In the first part of this study, we reviewed the charts and videonasendoscopic evaluations of 39 consecutive patients with confirmed or suspected velocardiofacial syndrome who underwent sphincter pharyngoplasty or pharyngeal flap from 1978 to 1996. The charts were reviewed to determine (1) the frequency of identification of abnormal pharyngeal pulsations; (2) whether such pulsations affected the conduct of the operative procedure; and (3) whether the presence of pulsations affected surgical morbidity and/or surgical outcome. None of the patients underwent any type of cervical vascular imaging study. In the second part of this study, we surveyed plastic surgeons with numerous years of experience participating on cleft-craniofacial teams, to ascertain practice patterns relating to the management of patients with velocardiofacial syndrome. The questions related specifically to the surgeons' behavior in relation to angiography and their awareness of any cases of surgical morbidity related to the cervical vascular system in patients with velocardiofacial syndrome. We were interested in discerning both how commonly this situation arises clinically and the distribution of the various types of operative procedures in common use. Of our 39 patients, 10 patients (26 percent) had detectable pulsations on preoperative nasendoscopy. Of these, five patients underwent sphincter pharyngoplasty and five underwent pharyngeal flap procedures. Preoperative instrumental and intraoperative clinical assessment of pulsatile vessels allowed velopharyngeal reconstruction in all patients without surgical morbidity. Results of the questionnaire indicated that most cleft surgeons do not routinely order cervical vascular imaging studies for all of their patients with velocardiofacial syndrome. About half of the respondents indicated that their operative approach was influenced by information obtained from angiographic studies. None of the surgeons queried were aware of any cases of surgical morbidity related to the cervical vascular system in patients with velocardiofacial syndrome. Nearly 50 percent of surgeons use pharyngeal flap procedures most frequently, whereas 22 percent of surgeons use sphincter pharyngoplasty most frequently. Results of this study support the safety of sphincter pharyngoplasty or pharyngeal flap procedures in patients with velocardiofacial syndrome without preparatory angiography. These procedures can be performed safely, even in patients having aberrant velopharyngeal pulsations. Given the market cost of magnetic resonance angiography ($1600), one must question the cost-efficacy of magnetic resonance angiography for routine use in the velocardiofacial syndrome population.

Blood Loss, Surgical↗

PubMed2004

True occult bladder perforation during placement of tension-free vaginal tape.

Bladder perforation is one of the most common complications of the trans-vaginal tape (TVT) procedure, and is generally identified on routine intra-operative cystoscopy. We present a case of occult bladder perforation occurring during the TVT procedure that could not be identified by cystoscopy. A 57-year-old woman underwent TVT placement for treatment of stress urinary incontinence. A bladder perforation, suspected because of clear fluid at one of the abdominal incision sites, could not be identified with cystoscopy, but was confirmed with bladder installation of sterile infant formula. The tape was removed and the bladder was drained for 48 h. The patient's recovery was uneventful and she subsequently underwent TVT placement without complication. Cystoscopy alone may be inadequate for identification of some bladder perforations during the TVT procedure. Awareness of alternative methods of identification is essential.

Cystoscopy↗

PubMed2006

A comparison of the SNAP II and BIS XP indices during sevoflurane and nitrous oxide anaesthesia at 1 and 1.5 MAC and at awakening.

BACKGROUND: Monitoring level of consciousness during anaesthesia, with the ability to predict the intentional or unintentional return to consciousness, is desirable. The purpose of this study was to compare two processed electroencephalographic depth of anaesthesia monitors (SNAP II and BIS XP) during sevoflurane and sevoflurane/nitrous oxide anaesthesia. METHODS: In total, 42 subjects received an interscalene block, followed by general anaesthesia with sevoflurane or sevoflurane/nitrous oxide. The indices were recorded at baseline, at 1.5 and 1.0 minimum alveolar concentration (MAC) equivalents, and during emergence. RESULTS: The SNAP and BIS indices decreased from baseline at 1.5 and 1.0 MAC equivalents, but there was no difference within groups between subjects who received nitrous oxide and those who did not. The SNAP index returned to baseline by 1 min before awakening and was higher than baseline at eye opening, but the BIS index remained below baseline at awakening. There was a bias of -1 (95% CI: -3 to 1) between the SNAP and BIS at baseline; this increased to 21 (95% CI: 19-23) during maintenance of anaesthesia and was 6 (95% CI: 4-8) at awakening. CONCLUSIONS: The SNAP index tracks loss of consciousness and emergence from sevoflurane and sevoflurane/nitrous oxide anaesthesia. There is significant bias between the SNAP and BIS indices and therefore, the indices are not interchangeable. The SNAP index returns to baseline before awakening, whereas the BIS index remains below baseline at awakening, suggesting that the SNAP index may be more sensitive to unintentional awareness.

Adolescent↗

PubMed2004

Interventional neurophysiologic monitoring.

PURPOSE OF REVIEW: Intraoperative neurophysiologic monitoring provides useful information on the functional status of the nervous system. This review focuses on recently published data concerning the impact of monitoring on patient outcome. RECENT FINDINGS: There is level I evidence to support the use of bispectral index monitoring to prevent awareness during anesthesia in high-risk patients. A number of randomized trials have shown that monitoring-guided anesthesia using the bispectral index or other devices will expedite recovery and improve perioperative drug utilization. There are also preliminary reports suggesting that anesthesia dictated by bispectral index monitoring may alter long-term outcome and reduce mortality. In surgical procedures, however, it is less clear whether neurophysiologic monitoring will improve patient outcome. Currently, the majority of data are derived from respective case series. Nonetheless, monitoring with somatosensory evoked potential has been shown to reduce postoperative neurologic deficits after spinal surgery. There is also evidence to suggest that electromyography and motor evoked potential are essential complements to somatosensory evoked potential for monitoring of spinal cord surgery. SUMMARY: Brain monitoring facilitates anesthetic drug administration. An increasing number of neurosurgical procedures will require some form of intraoperative neurophysiologic monitoring to achieve higher degrees of safety and accuracy. In many instances, the data derived from monitoring will guide and influence surgical decisions. In this context, neurophysiologic monitoring should be regarded as interventional.

Journal Article↗

PubMed1996

Blood conservation in acute care and critical care.

Blood conservation has evolved into an important issue in hospital-based medicine. Increased awareness of and worry about transfusion-associated diseases have prompted a focus on this important area. New technologies, including continuous intraarterial monitoring devices, microchemical technologies, new drug development (recombinant human erythropoietin and aprotinin) and intraoperative salvage techniques have made the concept of clinically important blood conservation possible. In this article, the authors review clinically important areas regarding blood conservation, which are subsequently detailed in this issue of AACN Clinical Issues. Emphasis is placed on the need for blood conservation in acute and critical care practice and the technologies available to achieve this goal.

Blood Loss, Surgical↗

PubMedDate not supplied

The immunization status and level of knowledge about hepatitis B virus infection among Nigerian surgeons.

Hepatitis B virus (HBV) infection is an occupational risk of surgeons especially in developing countries where asymptomatic carrier rate is about 15%. Despite better knowledge about mode of transmission and methods of prevention including use of active immunization, it still remains a threat. In this study, a questionnaire survey of Nigerian surgeons was conducted to ascertain their knowledge, and immunization status against HBV infection. Our study showed a 9.3% incidence of clinical HBV infection, poor perception of risk of infection, poor local availability of vaccines, and low uptake where same was available. Reasons cited for non-immunization are lack of awareness, cost, inertia and non-availability of vaccines. Only 10.2% of our respondents always used barrier methods, and 77.7% of our respondents do not check the immune status of their patients after sustaining an intraoperative sharp injury. The overall level of knowledge about HBV infection was deemed poor. We conclude with recommendations on how to improve knowledge about HBV infection and uptake of vaccines.

Adult↗

PubMed2004

The use of frozen section and immunohistochemistry for sentinel lymph node biopsy in breast cancer.

Intraoperative pathologic evaluation of the sentinel lymph node (SLN) may guide immediate (synchronous) completion axillary lymph node dissection (ALND) for up to two-thirds of patients with nodal disease for breast cancer. The false-negative rates average one-third of cases, and one must be aware of false-positive results as this would result in unnecessary and morbid completion ALND. Currently, the use of immunohistochemistry (IHC) is controversial. There is no question that cytokeratin staining improves the sensitivity; however, there is no evidence that any of these "positive" cells are clinically significant and warrant therapy. Prospective randomized trials will be necessary to confirm or debunk the hypothesis that "sub-micrometastatic" disease has clinical significance.

Algorithms↗

PubMed2001

Hirschsprung's disease, associated rare congenital anomalies.

OBJECTIVE: Hirschsprung's disease may be associated with a number of congenital anomalies of which Down's syndrome and intestinal atresias are commonly encountered. The study aimed to assess the impact of rare associated anomalies on the diagnosis and management of Hirschsprung's disease. METHODS: A retrospective review of the clinical presentation, diagnosis and outcome of thirty five consecutive newly diagnosed cases of Hirschsprung's disease encountered over two years was performed. RESULTS: Besides Down's syndrome (two), intestinal atresia (one) and pigmentary ocular defects (two), three rare anomalies (Occipital meningocele, Calcific meconium cyst with anal stenosis, Malrotation) were encountered in four of thirty five cases. The clinical features, radiologic anatomy and gross morphology of the bowel were unconventional and the diagnosis was supported by intraoperative acetylcholinesterase staining of biopsies. Though the diagnosis was relatively delayed in these cases, the outcome has been comparable to the rest. The dilemma in their diagnosis and management and their possible pathoembryology is discussed. CONCLUSION: Awareness of such associations and a specific investigative protocol is imperative for timely diagnosis and minimal morbidity in complex presentations of Hirschsprung's disease.

Abnormalities, Multiple↗

PubMed2002

Surgical identification of posterior lenticonus.

A 79-year-old patient was referred for cataract and high myopia. His optometrist noted difficult refraction. Biometry predicted an emmetropic intraocular lens power of +22.0 diopters. During cataract extraction, the typical features of posterior lenticonus were noted. A careful look for posterior lenticonus is suggested in cases in which there is a discrepancy between the biometry and refraction and no significant nuclear sclerosis to account for the high myopia. Surgeons should be aware of dehiscence or thinning of the posterior capsule while doing cataract extraction in these patients.

Aged↗

PubMed2001

Cervical flexion myelopathy after valproic acid overdose.

STUDY DESIGN: Case report and literature review of cervical flexion myelopathies. OBJECTIVE: To increase awareness that prolonged extreme neck flexion, in association with profound muscular relaxation, can produce a severe cervical myelopathy. SUMMARY OF BACKGROUND DATA: Similar case reports of cervical myelopathies have been documented in the neurosurgical literature after intraoperative prolonged neck flexion, and after forcible prolonged neck flexion during a robbery. To the authors' best knowledge, this is the first report of a cervical flexion myelopathy after a medication overdose, and the only clinical-pathologic correlation. METHODS: Retrospective case report with clinical, radiographic, and postmortem data available for analysis. RESULTS: A transverse myelopathy at the sixth cervical level developed in a 25-year-old woman after an overdose of valproic acid in a suicide attempt. She was found in the sitting position, with her neck in extreme flexion, where she had been for an estimated 18 hours. Magnetic resonance imaging showed that her cervical cord was enlarged, maximally at C6, with prominent paraspinal soft tissue swelling. The patient died of pulmonary embolism and pneumonia. Pathologic findings included transverse spinal cord necrosis at C6; central gray matter necrosis extended to several segments below this. CONCLUSION: Prolonged extreme neck flexion, in association with profound muscular relaxation, can produce a severe myelopathy that is at least partly related to compromise of the spinal cord's microcirculation.

Adult↗

PubMed2004

A BIS-guided study of sevoflurane requirements for adequate depth of anaesthesia in Caesarean section.

Caesarean section carries a high risk of awareness, especially in the period prior to neonatal delivery. We investigated the concentration of sevoflurane required to maintain bispectral index (BIS) < 60 until delivery occurred. We enrolled 23 parturients into an up-down sequential allocation study. The median effective end-tidal concentration (EC(50)) of sevoflurane was defined as that which maintained BIS < 60 between skin incision and delivery in 50% of patients. This was calculated using Dixon and Massey's method. Receiver operating characteristic curve analysis was used to establish BIS response probability thresholds. The EC(50) for sevoflurane was 1.22% (1.08-1.33, 95% CI). The probability of maintaining BIS < 60 was < 55% at a concentration of < 1.1%; this increased to 80% at concentrations of 1.2-1.3%. We conclude that sevoflurane concentrations of at least 1.2-1.3% should be administered in uncomplicated Caesarean section, so as to minimise the risk of awareness and recall.

Adult↗

PubMed2006

Cerebral state index response to incision: a clinical study in day-surgical patients.

BACKGROUND: Inadequate anaesthesia, with somatic/autonomic response or awareness, is often revealed at intubation and surgical incision. Anaesthetic depth monitors should be able to prevent this risk. This explorative study examined the ability of the cerebral state monitor to predict autonomic/somatic responses to incision. METHODS: Forty-two ASA I-II day-surgical patients [19 men and 23 females; mean age 52 (29-79) years, mean weight 77 (50-118) kg] were induced clinically with fentanyl/propofol with sevoflurane after placement of the laryngeal mask airway. The cerebral state index (CSI) was blindly recorded 4 min prior to and 4 min after incision. RESULTS: During the 4 min prior to incision, the mean CSI was 45 (16-62) and increased by 9 (-13-40) when the mean value for the first 4 min after incision was subtracted from the value prior to incision, corresponding to a relative change of 21% (-21-118). The change in CSI did not show any consistent relation to the value before incision. Five patients showed minor movements after incision and six patients had > 25% increase in blood pressure. Neither CSI nor the change in index differed between patients who did or did not respond somatically or autonomically to incision. The last CSI value just prior to incision was 44 for non-responders and 40 and 42 for somatic and autonomic responders, respectively. CONCLUSION: The CSI in the majority of patients was within acceptable ranges during clinically adjusted anaesthesia prior to incision but seems not to be able to reliably predict an autonomic or somatic response to incision.

Adult↗

PubMedDate not supplied

Intraventricular squamous papillary craniopharyngioma: report of a case with intraoperative imprint cytology.

BACKGROUND: Squamous papillary craniopharyngioma is a distinct entity, and its cytologic features may be misleading. Because of the rarity of this tumor, this case is being reported with a note on the cytologic features. CASE: A 56-year-old Malay man who had 1-month history of generalized lethargy was admitted for altered sensorium. On examination, he was found to have neck stiffness, bilateral papilledema and generalized atrophy of muscles, with reduced power in all limbs. Magnetic resonance imaging of the brain showed a solid mass in the third ventricle causing obstructive hydrocephalus. Intraoperative cytology of the mass diagnosed intraventricular meningioma. However, the final histopathologic examination revealed squamous papillary craniopharyngioma. CONCLUSION: Craniopharyngioma, squamous papillary type, is a rare entity and usually occurs in adults as an intraventricular solid tumor. Awareness of this entity will aid in arriving at the correct cytologic diagnosis.

Cell Nucleus↗

PubMed2003

Pulmonary sclerosing hemangiomas: new approach in patients with low cancer risk.

Three cases of sclerosing hemangioma managed differently are described. Thoracic surgeons should raise their awareness of this benign slow-growing tumor in the differential diagnosis of solitary pulmonary nodule. Radiographic evidence of expansion of such a lesion is not conclusive for malignancy, and should not affect its biological behavior. Intraoperative frozen-section histology may prevent unnecessary resection of lung tissue. Extracapsular enucleation is the treatment of choice for sclerosing hemangiomas.

Adult↗

PubMed1992

Practical treatment recommendations for the safe use of anaesthetics.

General anaesthesia is the reversible depression of central nervous system function. There is still no agreement over what constitutes depth of anaesthesia, and the clinical anaesthetist must thus titrate drug input according to clinical signs (heart rate, blood pressure, somatic movement, autonomic responses). The potency of inhalational agents may be expressed in terms of the MAC (minimum alveolar concentration); comparable end-points (including blood concentrations) have been proposed for the intravenous agents. Kinetic infusion regimens can be constructed for the intravenous agents to achieve the ED95 concentrations required to provide clinically adequate anaesthesia. However, because of individual differences in drug kinetics and dynamics, as well as the influences of disease states and intercurrent therapy, the clinician will titrate the dose according to response. Administration of volatile or intravenous anaesthetics by fixed regimens may result in either overdosage or the risk of patient awareness. The choice of anaesthetic drug is usually based on the nonhypnotic side effects of the different agents--including their central and regional cardiovascular effects, the speed and completeness of recovery, and the need to provide intraoperative analgesia. In addition, special techniques and drugs are often needed for neurosurgical, cardiothoracic and obstetric anaesthesia. All anaesthetic agents (inhalation and intravenous) have other side effects (such as cardiorespiratory depression and organ toxicity related to the liver or kidney). Both halothane and enflurane may be responsible for postoperative hepatic dysfunction, while the metabolism of enflurane can also result in nephrotoxicity in patients with pre-existing renal dysfunction. Isoflurane has been reported to cause 'coronary steal' in patients with ischaemic heart disease through its coronary vasodilator properties.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia↗