Prediction of difficult tracheal intubation

BACKGROUND AND OBJECTIVE

Preoperative bedside screening tests for difficult tracheal intubation may be neither sensitive nor specific enough for clinical use. The aim was to investigate if a combination of the Mallampati classification of the oropharyngeal view with either the thyromental or sternomental distance measurement improved the predictive value.

METHODS

A total of 212 (109 male, 103 female) non-obstetric surgical patients, aged >18 yr, undergoing elective surgical procedures requiring tracheal intubation were assessed preoperatively with respect to the oropharyngeal (modified Mallampati) classification, thyromental and sternomental distances. An experienced anaesthetist, blinded to the preoperative airway assessment, performed laryngoscopy and graded the view according to Cormack and Lehane's classification.

RESULTS

Twenty tracheal intubations (9%) were difficult as defined by a Cormack and Lehane Grade 3 or 4, or the requirement for a bougie in patients with Cormack and Lehane Grade 2. Used alone, the Mallampati oropharyngeal view, and thyromental and sternomental distances were associated with poor sensitivity, specificity and positive predictive values. Combining the Mallampati Class III or IV with either a thyromental distance <6.5cm or a sternomental distance <12.5cm decreased the sensitivity (from 40 to 25 and 20%, respectively), but maintained a negative predictive value of 93%. The specificity and positive predictive values increased from 89 and 27% respectively for Mallampati alone to 100%.

CONCLUSIONS

The findings suggest that the Mallampati classification, in conjunction with measurement of the thyromental and sternomental distances, may be a useful routine screening test for preoperative prediction of difficult tracheal intubation.

Comparison of ocular microtremor and bispectral index during sevoflurane anaesthesia

BACKGROUND

A practical and reliable monitor of depth of anaesthesia would be a major advance on current clinical practice. None of the present monitors is both simple to use and accurate. Ocular microtremor (OMT) is a physiological tremor that is suppressed by propofol in a dose-dependent manner. We studied OMT during propofol induction and nitrous oxide-oxygen-sevoflurane maintenance of anaesthesia in 30 patients, and compared OMT with the bispectral index (BIS) as a predictor of response to verbal command.

METHODS

OMT was measured using the closed-eye piezoelectric strain-gauge technique. OMT and BIS were measured at specific times during the anaesthetic, including at loss of consciousness, at end-tidal sevoflurane 1 and 2%, and at emergence.

RESULTS

OMT decreased significantly after induction, did not decrease as end-tidal sevoflurane was increased from 1 to 2%, and increased at emergence in all patients. By logistic regression, OMT was more sensitive and specific than BIS in distinguishing the awake from the anaesthetized state (OMT, 84.9 and 93.1% respectively; BIS, 75.7 and 69.0%).

CONCLUSIONS

OMT is suppressed by sevoflurane and accurately predicts response to verbal command. OMT may be a useful monitor of depth of hypnosis.

The effects of fenoldopam on renal function in patients undergoing elective aortic surgery

BACKGROUND AND OBJECTIVE

Postoperative renal impairment is a recognized complication of infrarenal aortic cross-clamping. Our hypothesis was that the renal vasodilating and natriuretic effects of fenoldopam mesylate, a selective dopamine (DA1) agonist, would preserve renal function in patients undergoing elective infrarenal aortic cross-clamping.

METHODS

A prospective, randomized, double blind controlled clinical trial was performed. Twenty-eight ASA II-III patients undergoing elective aortic surgery requiring infrarenal aortic cross-clamping were studied. According to random allocation, patients received either fenoldopam (0.1 microg kg(-1) min(-1)) or placebo intravenously prior to surgical skin incision until release of the aortic clamp. Plasma creatinine, creatinine clearance, urinary output, fractional excretion of sodium, and free water clearance were measured: (a) prior to admission to hospital; (b) during the period from insertion of the urinary catheter until application of the aortic cross-clamp; (c) during the period of aortic cross-clamping; (d) 0-4 h, and (e) 4-8 h after release of the clamp and on days 1, 2, 3, and 5 postoperatively.

RESULTS

Fenoldopam (0.1 microg kg(-1)min(-1)) administration was not associated with haemodynamic instability. On application of the aortic cross-clamp creatinine clearance decreased significantly in the placebo (83 +/- 20 to 42 +/- 29 mL min(-1) (mean +/- SD)) (P < 0.01) but not in the fenoldopam group, and this decrease persisted for at least 8 h after release of the cross-clamp (83 +/- 20 to 54 +/- 33 mL min(-1) (mean +/- SD)) (P < 0.05). Plasma creatinine concentration increased significantly from baseline on the first postoperative day in the placebo group (87 +/- 12 to 103 +/- 28 micromolL(-1) (mean +/- SD)) (P < 0.01) but not in the fenoldopam group.

CONCLUSIONS

These findings are consistent with the hypothesis that fenoldopam possesses a renoprotective effect during and after infrarenal aortic cross-clamping.

Inhibition of cyclooxygenase-2 aggravates doxorubicin-mediated cardiac injury in vivo

The clinical use of doxorubicin, an anthracycline chemotherapeutic agent, is limited by cardiotoxicity, particularly when combined with herceptin, an antibody that blocks the HER2 receptor. Doxorubicin induces cyclooxygenase-2 (COX-2) activity in rat neonatal cardiomyocytes. This expression of COX-2 limits doxorubicin-induced cardiac cell injury, raising the possibility that the administration of a prostaglandin may protect the heart during the in vivo administration of doxorubicin. Doxorubicin (15 mg/kg) administered to adult male Sprague Dawley rats induced COX-2 expression and activity in cardiac tissue. Prostacyclin generation measured as the excretion of 2,3-dinor-6-keto-PGF(1alpha) also increased, and this was blocked by a COX-2 inhibitor, SC236. In contrast, administration of a COX-1 inhibitor SC560 at a dose that reduced serum thromboxane B2 by more than 80% did not prevent the doxorubicin-induced increase in prostacyclin generation. Doxorubicin increased cardiac injury, detected as a rise in plasma cardiac troponin T, serum lactate dehydrogenase, and cardiomyocyte apoptosis; this was aggravated by coadministration of SC236 but not SC560. The degree of injury in animals treated with a combination of doxorubicin and SC236 was attenuated by prior administration of the prostacyclin analogue iloprost. These data raise the possibility of protecting the heart during the administration of doxorubicin by prior administration of prostacyclin.

Dopexamine hydrochloride does not modify hemodynamic response or tissue oxygenation or gut permeability during abdominal aortic surgery

PURPOSE

To assess the effects of intraoperative infusion of dopexamine (a DA-1 and B2 adrenoreceptor agonist) on hemodynamic function, tissue oxygen delivery and consumption, splanchnic perfusion and gut permeability following aortic cross- clamp and release.

METHODS

In a randomised double blind controlled trial 24 patients scheduled for elective infrarenal abdominal aortic aneurysm repair were studied in two centres and were assigned to one of two treatment groups. Group I received a dopexamine infusion starting at 0.5 microg x kg(-1) x min(-1) increased to 2 microg x kg(-1) x min(-1) maintaining a stable heart rate; Group II received a placebo infusion titrated in the same volumes following induction of anesthesia. Measured and derived hemodynamic data, tissue oxygen delivery and extraction and gut permeability were recorded at set time points throughout the procedure.

RESULTS

Dopexamine infusion (0.5 -2 microg x kg x min(-1)) was associated with enhanced hemodynamic function (MAP 65 +/- 5.5 vs 92 +/- 5.7 mm Hg, P = <0.05) only during the period of aortic cross clamping. However, during the most part of infrarenal abdominal aortic surgery, dopexamine did not reduce systemic vascular resistance index, mean arterial pressure nor oxygen extraction compared with the control group. The lactulose/ rhamnose permeation ratio was elevated above normal in both groups (0.22 and 0.29 in groups I and II respectively).

CONCLUSIONS

Dopexamine infusion (0.5 -2 microg x kg(-1) x min(-1)) did not enhance hemodynamic function and tissue oxygenation values during elective infrarenal abdominal aortic aneurysm repair.

Physiologic changes during laparoscopy

The short-term benefits of minimal access techniques include less pain, early mobilization, and shorter hospital stay. Nonetheless, significant data have accumulated regarding the complications associated with laparoscopic techniques, including those that are unique to laparoscopic surgery such as bile duct injury and disruption of major blood vessels. Other problems such as myocardial ischemia and respiratory acidosis are associated with the cardiopulmonary effects of pneumoperitoneum and systemic CO2 absorption. These physiologic changes, although tolerated by healthy patients, could have particular adverse consequences for infirm and critically ill patients. It would appear that minimizing IAP during insufflation decreases the risk of potentially marked cardiovascular changes and regional blood flow alterations. In turn, this could arguably decrease the risk of perioperative myocardial events, or organ dysfunction or failure. Laparoscopy in the critically ill patient is questionable because the role is not established. An ICU patient has little to gain from the benefits of early mobilization. Conversely, in the presence of raised ICP or borderline organ function, the physiologic changes associated with pneumoperitoneum and laparoscopy could have profound detrimental effects.

Association of involvement in psychological self-regulation with longer survival in patients with metastatic cancer: an exploratory study

There have been numerous anecdotal claims that when patients are dedicated users of a variety of psychological self-regulation strategies, including relaxation, mental imaging, cognitive restructuring and meditation, such dedication may have a life-prolonging effect. Our aim was to test this possibility more rigorously, in patients with metastatic cancer.A prospective, longitudinal, correlative study was carried out on 22 patients with varying kinds of medically incurable metastatic cancer. The intervention was one year of weekly group psychological therapy. Extensive verbal data (patients' written homework and therapists' notes) were collected over the year. The extent of each patient's involvement with psychological work was estimated following a qualitative analysis of these data. Patients were classed as showing high, moderate, or low involvement on the basis of a quantitative rating of categories defined by the analysis. These three subgroups did not differ significantly in their expected median survival duration as estimated from independent quantitative predictions by a large panel of oncologists who analyzed the patients' medical charts at time of study entry.A significant relationship was found between degree of involvement in psychological work and survival duration. Results are presented as Kaplan-Meier survival curves (Fig. 2;P = 0. 006, Log Rank test) and as a graphic display of the median survival of each of the three groups (Fig. 3). The main likely confounders (medical status, age, quality of life, and attendance at therapy) were similar across subgroups and did not change the relation between psychological work and survival duration. Limitations in the design are discussed. However, the strong effects observed support clinical observations that dedicated involvement in psychological self-regulation may prolong the life of some patients with metastatic cancer.

Traumatic bilateral internal carotid artery dissection following airbag deployment in a patient with fibromuscular dysplasia

This case describes a 39-yr-old male, presenting with left hemiplegia after a road traffic accident involving frontal deceleration and airbag deployment. Brain computerized tomography (CT) scan revealed a right parietal lobe infarct. Contrast angiography demonstrated bilateral internal carotid artery dissection and fibromuscular dysplasia. The patient was treated with systemic heparinization. Neurological improvement, evidenced by full return of touch sensation, proprioception and nociception began 10 days after the injury. To our knowledge, this is the first case report of carotid artery dissection associated with airbag deployment. Forced neck extension in such settings may result in carotid artery dissection because of shear force injury at the junction of the extracranial and intrapetrous segments of the vessel. Clinicians should consider carotid artery injury when deterioration in neurological status occurs after airbag deployment. We propose that the risk of carotid artery dissection was increased by the presence of fibromuscular dysplasia.

Adjuvant psychological therapy for cancer patients: putting it on the same footing as adjunctive medical therapies

A comparison is made between the models guiding the administration of adjuvant material remedies, such as chemotherapy, and 'adjunctive psychological therapy' (APT), in the treatment of cancer. It is argued that patients would benefit if APT were supplied subject to the same indications as adjuvant chemotherapy.

A prospective, longitudinal study of the relationship of psychological work to duration of survival in patients with metastatic cancer

This study is a prospective, longitudinal investigation of the psychological factors associated with the duration of survival in patients with metastatic cancers of various kinds who were receiving group psychotherapy. A correlative approach rather than an experimental (trials) design was used in the study because our aim was to relate the psychological attributes of each individual to survival rather than to test the efficacy of the intervention. Twenty-two patients with medically incurable metastatic cancer of various kinds received weekly group psychotherapy for up to 1 year, the great majority remaining well enough to attend the group for at least 8 months. During this time, they provided extensive verbal data, through written homework, and from notes taken by the therapists at interviews and during group sessions. These data were subjected to detailed qualitative analysis, as a result of which a number of psychological themes were defined. A quantitative rating was assigned to the data for each theme in each individual patient through team discussions. The scores for the individual themes were summed to produce a 'total psychological score', representing the degree of each patient's involvement with psychological self-help work. The values for each patient were then related to his or her survival duration. Cox regression analyses showed that this composite score, and five of six major themes, were significantly related to survival duration. These themes were: ability to act and change; willingness to initiate change; application to self-help work; relationships with others; and quality of experience. In contrast, there was no relationship between survival and four standard psychometric measures taken at the onset of therapy. However, results on a 5-point scale measuring the subject's expectancy that psychological efforts would affect the disease showed a strong relationship to survival. To control for differences in severity of disease as a factor possibly influencing psychological work, the analyses were repeated, using the survival duration predicted for each patient by a panel of oncologists as a covariate. Closely similar results were obtained. Limitations on the interpretation of the results are discussed. Within these limits, it appears that there is a strong association between longer survival and psychological factors related to the involvement of cancer patients in psychological self-help activities. While causality cannot be inferred, reasons are given for believing that this is not a result of the disease influencing the patients' psychology, but rather the converse.

Spinal cord infarction and tetraplegia--rare complications of meningococcal meningitis

A previously healthy 25-yr-old female developed flaccid areflexic tetraplegia, with intact cranial nerve function, 36 h after the diagnosis of bacterial meningitis. Polymerase chain reaction studies of cerebrospinal fluid and blood were positive for Neisseria meningitidis, serogroup B. Magnetic resonance of the cervicothoracic spine revealed increased signal intensity and expansion in the lower medulla, upper cervical cord and cerebellar tonsils. Neurosurgical consultation recommended hyperventilation, dexamethasone and regular mannitol therapy rather than decompressive intervention. The clinical course over the following 12 days was complicated by the development of progressive central nervous and multisystem organ failure with disseminated intravascular coagulopathy. Autopsy revealed cerebral oedema with cystic infarction extending from the medulla to the upper cervical cord and cerebellar tonsils. Flaccid areflexic tetraplegia with spinal cord infarction has not been reported following bacterial infection in an adult. The clinical implications would suggest complete central nervous system evaluation of patients recovering from meningococcal meningitis, since spinal cord lesions, although uncommon, do occur. In those very rare situations where a patient develops significant peripheral neurological deficits, urgent magnetic resonance imaging is warranted, to rule out an infective focus or an underlying anatomical anomaly.

The effects of midazolam on pure tone audiometry, speech audiometry, and audiological reaction times in human volunteers

Auditory evoked potentials are effected by benzodiazepines, as is cortical processing of auditory stimuli. The effect of benzodiazepines on auditory sensitivity has not, however, been studied. We designed the present study to investigate the effect of sedative doses of midazolam on pure tone and speech audiometry and on audiological reaction times in healthy volunteers. Thirty volunteers underwent baseline audiological assessment for pure tones and speech and had their audiological reaction times measured at 10 and 50 dB above their threshold hearing level at a frequency of 1 kHz. Subjects were then randomly assigned to one of two groups. Group A (n = 15) received midazolam (0.04 mg/kg) IV, and Group B (n = 15) received a similar volume of placebo IV. The audiological tests were repeated 5 min later, and performance was compared with baseline data. Scheffé post hoc tests were used to assess the significance of changes in each group. There was no pre- to posttest change in audiological performance in either the placebo group (P = 0.194) or the midazolam group (P = 0.957). Speech audiometry performance was likewise unaffected by midazolam (P = 0.154). Reaction time at the 10-dB and 50-dB sensation levels were both significantly prolonged after midazolam administration (P = 0.023 and P = 0.012, respectively). In this study, we demonstrate that sedation with midazolam (0.04 mg/kg) does not alter pure tone or speech audiometric thresholds, but it does significantly delay the reaction time to auditory stimuli. Medical practitioners should advise midazolam-sedated patients of their impaired reaction to auditory warning signals (e.g., traffic and car horns) as part of the day-ward discharge recommendations.

IMPLICATIONS

In this study, we demonstrate that sedation of healthy volunteers with the benzodiazepine midazolam, in the common clinical dosage, does not affect their hearing capability as measured by pure tone and speech audiometry. However, one's ability to react to auditory signals is impaired after midazolam, which may have implications for patients after day-case procedures.