Sympathetic Nervous System Does Not Mediate Reflex Pupillary Dilation during Desflurane Anesthesia

Background: Pupil size is determined by an interaction between the sympathetic and parasympathetic divisions of the autonomic nervous system. Noxious stimulation dilates the pupil in both unanesthetized and anesthetized humans. In the absence of anesthesia, dilation is primarily mediated by the sympathetic nervous system. In contrast, pupillary dilation in cats given barbiturate or cloralose anesthesia is mediated solely by inhibition of the midbrain parasympathetic nucleus. The mechanism by which noxious stimuli dilate pupils during anesthesia in humans remains unknown. Accordingly, the authors tested the hypothesis that the pupillary dilation in response to noxious stimulation during desflurane anesthesia is primarily a parasympathetic reflex.

Methods: In six volunteers, the alpha-1 adrenergic receptors of the iris musculature were blocked by unilateral administration of topical dapiprazole; six other volunteers were given unilateral topical tropicamide to block the muscarinic receptors in the iris. Desflurane anesthesia was subsequently induced in all volunteers. Sympathetic nervous system activation, with reflex dilation of the pupil, was produced by noxious electrical stimulation during 4% and 8% end-tidal desflurane, and by a rapid 4%-to-8% step-up in the desflurane concentration. Pupil diameter and the change in pupil size induced by a light stimulus (light reflex amplitude) were measured with infrared pupillometry.

Results: Dapiprazole drops produced a Horner's miosis, but pupils were equally small after induction of anesthesia. Pupillary dilation after noxious stimulation and desflurane step-up was identical in the unblocked and dapiprazole-blocked pupils. After tropicamide administration, the pupil was dilated and the light reflex was completely inhibited. Noxious stimulation nonetheless produced a slight additional dilation.     

The effect of antiemetics on pupillary reflex dilation during epidural/general anesthesia

The effect of dopamine D2 receptor antagonists, such as chlorpromazine and haloperidol, on pupil size in awake subjects suggests that these drugs might also alter pupillary reflex dilation and pupil size during general anesthesia. Forty-seven patients undergoing lower abdominal surgery under combined epidural/general anesthesia were randomized to receive one of the 5 following open labeled drugs: 10 mL saline, 0.13 mg/kg ondansetron, 0.25 mg/kg metoclopramide, 0.5 mg/kg metoclopramide, or 0.02 mg/kg droperidol. Three measurements of reflex dilation were taken at 5-min intervals and after the last measurement (time 0) the drug was administered. Measurements were then taken 5, 10, 20, and 40 min after I.V. drug administration. Reflex dilation was induced by intermittent noxious stimulation of the C5 dermatome with a tetanic electric current (60-70 mamp, 100 Hz, 3-s duration) after a stable level of epidural analgesia had been established with 3/8% bupivacaine and maintained with a continuous infusion. Metoclopramide produced a small decrease in pupil diameter and transiently depressed reflex dilation, whereas droperidol decreased pupil size at 10 min and depressed reflex dilation throughout the 40-min study period. Maximal change in reflex dilation was -6.6 +/- 3.3 mm-sec after droperidol. Ondansetron had no effect on pupil diameter or reflex dilation. When pupillary diameter measurements are used to gauge opioid levels during experimental conditions or during surgical anesthesia, antiemetic medication acting on the dopamine D2 receptor should be avoided. IMPLICATIONS: Miosis is often considered an effect of opioid administration during general anesthesia, but other drugs, such as antiemetics, might produce a similar effect on the pupil. This study demonstrates that 2 antiemetics, droperidol and metoclopramide, constrict the pupil and block the pupillary dilation brought about by nociceptive stimuli.     

Alfentanil Blocks Reflex Pupillary Dilation in Response to Noxious Stimulation But Does Not Diminish the Light Reflex

Background: Estimation of the micro-agonist opioid effect in anesthetized and paralyzed patients is often imprecise and can be obscured by concomitant administration of drugs that affect the sympathetic nervous system, such as beta-adrenergic blocking agents. As an alternative to hemodynamic measures of opioid effect, the authors tested the hypothesis that the pupillary light reflex or pupillary reflex dilation correlated with alfentanil concentrations during isoflurane anesthesia.

Methods: Six volunteers were anesthetized on 4 days with 0.8% isoflurane. Alfentanil was administered intravenously to target total plasma concentrations of 0, 25, 50, and 100 ng/ml. A 5-s tetanic electrical stimulus was applied to the skin. Pupil size and the pupillary light reflex were recorded before and after alfentanil administration, and before and for 8 min after the stimulus.

Results: Alfentanil exponentially impaired reflex pupillary dilation, decreasing the maximum response amplitude from 5 mm at 0 ng/ml, to 2.3 mm at 25 ng/ml, to 1.0 mm at 50 ng/ml, and finally to 0.2 mm at 100 ng/ml. In contrast, only the highest concentration of alfentanil depressed the dilation of the pupil in the first 2 s after the stimulus. Alfentanil administration had no effect on the pupillary light reflex.     

Mechanism of pupillary reflex dilation in awake volunteers and in organ donors

BACKGROUND: The mechanism of reflex pupillary dilation was investigated in eight patients who were declared brain dead after rupture of intracranial vascular malformations and in eight awake volunteers. The authors hypothesized that the reflex was primarily a spinal sympathetic reflex that would be blocked by topical application of the alpha1-adrenergic blocking agent dapiprazole and that it would be present in organ donors with intact spinal reflexes and no history of hypoxia. METHODS: In volunteers, pupil size was measured with an infrared pupillometer while brief painful electric stimuli were delivered to the finger. Pain was assessed with a visual analog scale and adjusted with each volunteer to equal 3 on a visual analog scale of 0-10. Subjects were studied before and after topical application of the alpha1-adrenergic antagonist dapiprazole. In organ donors, the authors measured pupil size after high-intensity tetanic electric stimulation and in dapiprazole-blocked and -unblocked pupils after surgically induced nociception. RESULTS: In volunteers, the pupil dilated 0.43 +/- 0.23 mm after nociceptive stimuli. Dapiprazole eyedrops blocked this dilation, confirming that the reflex in awake humans is primarily a sympathetic reflex. Baseline diameters were 5.7 +/- 0.5 mm before dapiprazole and 4.1 +/- 0.9 mm after dapiprazole. In organ donors, a tetanic electric current failed to dilate the pupil, whereas the skin incision dilated the pupil 0.4 +/- 0.4 mm, but this dilation was not blocked by dapiprazole. CONCLUSION: The authors conclude that pupillary reflex dilation, as it is clinically performed in awake subjects by stimulating somatic nociceptors, is a sympathetic reflex. Because it is not present in organ donors, the neural pathway must require a supraspinal component for completion.     

Mechanism of Pupillary Reflex Dilation in Awake Volunteers and in Organ Donors

Background: The mechanism of reflex pupillary dilation was investigated in eight patients who were declared brain dead after rupture of intracranial vascular malformations and in eight awake volunteers. The authors hypothesized that the reflex was primarily a spinal sympathetic reflex that would be blocked by topical application of the [alpha]1-adrenergic blocking agent dapiprazole and that it would be present in organ donors with intact spinal reflexes and no history of hypoxia.

Methods: In volunteers, pupil size was measured with an infrared pupillometer while brief painful electric stimuli were delivered to the finger. Pain was assessed with a visual analog scale and adjusted with each volunteer to equal 3 on a visual analog scale of 0-10. Subjects were studied before and after topical application of the [alpha]1-adrenergic antagonist dapiprazole. In organ donors, the authors measured pupil size after high-intensity tetanic electric stimulation and in dapiprazole-blocked and -unblocked pupils after surgically induced nociception.

Results: In volunteers, the pupil dilated 0.43 +/- 0.23 mm after nociceptive stimuli. Dapiprazole eyedrops blocked this dilation, confirming that the reflex in awake humans is primarily a sympathetic reflex. Baseline diameters were 5.7 +/- 0.5 mm before dapiprazole and 4.1 +/- 0.9 mm after dapiprazole. In organ donors, a tetanic electric current failed to dilate the pupil, whereas the skin incision dilated the pupil 0.4 +/- 0.4 mm, but this dilation was not blocked by dapiprazole.     

The Brain Trauma Foundation. The American Association of Neurological Surgeons. The Joint Section on Neurotrauma and Critical Care. Pupillary diameter and light reflex

The pupillary diameter and the pupilloconstrictor light reflex are the two parameters that have been studied extensively in relation to prognosis. Accurate measurement of pupil diameter or the constrictor response or the duration of the response has not been performed in studies on traumatic brain-injured individuals--for lack of a standardized measuring procedure. The following is recommended: 1. Pupillary light reflex for each eye should be used as a prognostic parameter. 2. The duration of pupillary dilation and fixation should be documented. 3. A pupillary size of >4 mm is recommended as the measure for a dilated pupil. 4. A fixed pupil should be defined as no constrictor response to bright light. 5. Right or left distinction should be made when the pupils are asymmetric. 6. Hypotension and hypoxia should be corrected before assessing pupils for prognosis. 7. Direct orbital trauma should be excluded. 8. Pupils should be reassessed after surgical evacuation of intracranial hematomas.     

The ciliospinal reflex in pentobarbital coma

OBJECT: This study was conducted to delineate the ciliospinal reflex (CSR), which is defined as pupillary dilation caused by a noxious stimulus to the face or head. The authors anecdotally observed that patients in a pentobarbital coma have a CSR that can mimic pathological conditions. A pentobarbital coma obscures the results of the neurological examination in patients with potentially life-threatening cerebral edema; pupil size and reactivity are the only readily monitored signs. Any condition that incorrectly suggests evolving intracranial pathological processes can lead to unnecessary clinical actions. METHODS: The authors evaluated six consecutive patients in the neurointensive care unit in whom a pentobarbital coma had been induced, documenting the presence and duration of the CSR. The CSR was always bilateral and symmetrical, manifesting as enlarged (6-8 mm), seemingly nonreactive pupils continuing from 1 to 6 minutes and was usually seen after routine nursing maneuvers. The pupils appeared nonreactive to short flashes of direct light but did react if longer flashes were used. CONCLUSIONS: Recognition of the CSR can potentially lead to reduction of unnecessary transportation and complicating medical interventions in critically neurologically ill patients in whom a pentobarbital coma has been induced.     

Safety and efficacy of bilateral topical application of rocuronium bromide for mydriasis in European kestrels (Falco tinnunculus)

The avian iris is mainly composed of striated muscle fibers, and the topical parasympatholytic drugs used in mammals to induce pupil dilation are ineffective in birds. The achievement of mydriasis in conscious birds is only possible by using neuromuscular blocking agents such as curariform drugs. To determine the efficacy of the neuromuscular blocking agent rocuronium bromide as a mydriatic agent in European kestrels (Falco tinnunculus) and to assess possible adverse effects due to its use, 10 kestrels received a single topical instillation with a pipette of 0.12 mg of rocuronium in each eye (total dose, 0.24 mg/bird). Pupil diameter was measured with a pupillary gauge, and pupillary light reflex was assessed by using a standard light source from time zero (Tbase) to 250 minutes after application (T250). Baseline pupil size (Tbase) was 3.30 (0.71) mm in both eyes. Maximal mydriasis was achieved at T90 minutes with a mean (SD) pupillary diameter of 6.30 (0.42) mm and 6.35 (0.41) mm in the right eye and left eye, respectively. At the dose used, rocuronium bromide induced a consistent bilateral simultaneous mydriasis without noticeable adverse effects, and it can be considered a reliable and safe topical mydriatic agent in kestrels.     

Monitorage de la dilatation pupillaire dans l’évaluation d’une tolérance aiguë au rémifentanil en chirurgie cardiaque

Introduction

Remifentanil is a powerful morphinic agonist often ordered for anaesthesia. The use of peroperative large doses of this opioid increases the risk to develop postoperative hyperalgesia and acute tolerance. But how early these effects can occur? Despite the fact that these effects could be masked during the preoperative time because of general anaesthesia, it seems they could occur precociously. In order to try to describe this time, this study evaluated the acute tolerance under general anaesthesia requiring large doses of remifentanil by using an effective peroperative monitoring of nociception: the continuous pupillary diameter monitoring.

Materials and methods

In this prospective observational clinical study, a continuous infusion of remifentanil was started at a range of 0.3 μg/kg/min after induction of anaesthesia by using propofol (TIVA), remifentanil bolus and cisatracurium. The pupil monitoring started 10 min later (T + 10 min) and lasted until the surgical incision (T + 65 min). So, there was no surgical stimulus during this time.

Results

Thirty patients undergoing major cardiac or vascular surgery were included in this study. The continuous pupil diameter evaluation showed a significant increase of the pupil diameter from T + 45 min. No significant variation of heart rate, blood pressure, bispectral index (BIS) values were observed.

Discussion

The development of acute remifentanil tolerance could possibly explain these results. If evaluations with continuous pupillary diameter monitoring are still limited, these results suggest that the use of powerful opioids such as remifentanil should be associated with a N-methyl-d-aspartate (NMDA) receptor antagonist agent, including short time administrations.     

Brain stem blood flow, pupillary response, and outcome in patients with severe head injuries

OBJECTIVE: Acute pupillary dilation in a head-injured patient is a neurological emergency. Pupil dilation is thought to be the result of uncal herniation causing mechanical compression of the IIIrd cranial nerve and subsequent brain stem compromise. However, not all patients with herniation have fixed and dilated pupils, and not all patients with nonreactive, enlarged pupils have uncal herniation. Therefore, we have tested an alternative hypothesis that a decrease in brain stem blood flow (BBF) is a more frequent cause of mydriasis and brain stem symptomatology after severe head injury. We determined the relation of BBF to outcome and pupillary response in patients with severe head injuries. METHODS: One hundred sixty-two patients with a Glasgow Coma Scale score of 8 or less underwent stable xenon computed tomographic blood flow determination at the level of the superior colliculus, and this blood flow was correlated with pupillary features, intracranial pressure, computed tomographic scan pathology, and outcome. RESULTS: A BBF of less than 40 ml/100 g/min was significantly associated with poor outcome (P < 0.009). In patients with bilaterally nonreactive pupils, the BBF was 30.5+/-16.8 ml/100 g/min, and in those with normally reactive pupils, the BBF was 43.8+/-18.7 ml/100 g/min (P < 0.001). Intracranial pressure and the presence of a brain stem lesion observed on the computed tomographic scan did not correlate with BBF, pupillary size, or reactivity. Unfavorable outcome at 12 months was directly related to age (P = 0.062) and inversely related to pupillary responsiveness (P = 0.0006), pupil size (P = 0.005), and BBF of less than 40 ml/100 g/min (P = 0.009). CONCLUSION: These findings suggest that pupillary dilation is associated with decreased BBF and that ischemia, rather than mechanical compression of the IIIrd cranial nerve, is an important causal factor. More important, pupil dilation may be an indicator of ischemia of the brain stem. If cerebral blood flow and cerebral perfusion pressure can be rapidly restored in the patient with severe head injury who has dilated pupils, the prognosis may be good.     

Predictors of functional outcome after hanging injury

Purpose

Suicide becomes a serious problem in today's society and hanging is a common method of suicide. We want to find the factors which can predict the final functional outcomes of these cases.

Reduced pupillary unrest. Autonomic nervous system abnormality in diabetes mellitus

Pupillary unrest (fluctuations in pupil size) was measured by infrared television videopupillography in 80 insulin-dependent diabetic patients (age 25-43 yr, diabetes duration 0-35 yr) and 26 control subjects (age 26-39 yr). In darkness, pupillary unrest was 21% less in diabetic subjects than in controls. During prolonged and brief illumination, pupillary unrest was 35 and 37% less in diabetic subjects than in controls, respectively, and in both cases the unrest was inversely correlated to the duration of diabetes. There were inverse correlations between 1) vibratory perception threshold, long-term high blood glucose levels, and severity of retinopathy, and 2) pupillary unrest in darkness and during prolonged illumination. The fractional reduction in pupil size (relative miosis) was 19% less during prolonged illumination in diabetic subjects than in controls and was positively correlated to the pupillary unrest in both groups. For a given fractional reduction in pupil size during illumination, diabetic subjects still had a smaller unrest than controls. Pupil size in darkness was 19% smaller in diabetic subjects than in controls, and in diabetic subjects it was positively correlated to the unrest in darkness and during prolonged and brief illumination. None of the pupillary abnormalities showed correlation to biomicroscopic changes in the iris. The autonomic nervous system abnormalities reflected in the pupil in longstanding diabetes are 1) a reduction in pupillary unrest in light and in darkness, more pronounced in light, 2) a reduction in the ability to maintain miosis in continuous light, and 3) a reduction in size.     

Cholinergic dysfunction in cognitive impairments after aneurysmal subarachnoid hemorrhage

OBJECTIVE: Although cognitive impairments have been observed after subarachnoid hemorrhage (SAH), little is known about their neurobiological bases. To examine cholinergic function in such patients, we used a known test for Alzheimer's disease based on an exaggerated pupil dilation response to a cholinergic antagonist, tropicamide (the tropicamide drop test). METHODS: Seventeen patients who were treated surgically after aneurysmal SAH were divided into two groups on the basis of their scores on the Mini-Mental State Examination (MMSE): Group A (MMSE > or =28) and Group B (MMSE < or =27). The mean interval of time between surgery and administration of the MMSE was 4.7 +/- 2.1 years for Group A and 4.2 +/- 1.3 years for Group B. The tropicamide drop test was performed within 1 month after the MMSE for each patient. After measurement of the baseline pupil diameter (R1, right pupil size: L1, left pupil size), one drop of 0.01% tropicamide was applied to the right eye and physiological saline to the left eye. Pupil diameter (R2, right pupil size; L2, left pupil size) was then remeasured. Data were represented as the dilation ratio of the right pupil (R2/R1) and as the relative dilation ratio of the right pupil to that of the left pupil (R2L1/R1L2). RESULTS: The mean dilation ratio of the right pupil (R2/R1) was higher in Group B (1.13 +/- 0.09) than in Group A (1.07 +/- 0.11), although the difference did not reach statistical significance (P = 0.18). The relative dilation ratio (R2L1/R1L2) was significantly higher in Group B (1.41 +/- 0.36) than in Group A (1.06 +/- 0.20) (P < 0.05). CONCLUSION: We determined cholinergic dysfunction in patients with cognitive impairment after SAH on the basis of the pupillary response to tropicamide. The results provide an insight into the pathophysiology of cognitive impairments after SAH, which might lead to future treatment strategies.     

Improving diagnostic acumen in pupillary evaluation: a review for the primary care physician

Many primary care physicians perform only a superficial pupillary evaluation as part of the physical examination. The authors review several maneuvers that require no special equipment and help to improve diagnostic yield. The "swinging flashlight" test aids in detecting a relative afferent pupillary defect. When a patient has anisocoria, the initial diagnostic challenge is to determine which pupil is abnormal. Comparing the extent of pupillary inequality under both dim and bright illumination almost always identifies the dysfunctioning pupil(s) and narrows the differential diagnosis. The authors compare third-nerve palsy and Horner's syndrome as causes of anisocoria and review light-near dissociation, another important category of pupillary dysfunction. This latter phenomenon is seen in the Argyll Robertson pupil, the dorsal midbrain syndrome, and the tonic pupil syndromes. Pupillary size and activity are key diagnostic parameters in the evaluation of patients in coma. Structural and mechanical iris defects are also frequently responsible for pupillary anomalies.     

Effects of epidural anesthesia with 0.2% and 1% ropivacaine on predicted propofol concentrations and bispectral index values at three clinical end points

STUDY OBJECTIVE: To compare the effects of 0.2% epidural ropivacaine and those of 1% epidural ropivacaine on predicted propofol concentrations and bispectral index scores (BISs) at three clinical end points. DESIGN: Randomized double-blind study. SETTING: University hospital. PATIENTS: Thirty-five (35) ASA physical status I and II patients scheduled for elective surgery of the lower abdomen. INTERVENTIONS: Patients were randomly divided into 2 groups to receive epidurally 8 mL of 0.2% or 1% ropivacaine followed by the same solution at a rate of 6 mL/h. MEASUREMENTS: Twenty minutes after starting ropivacaine, a target-controlled infusion of propofol was started to provide a predicted blood concentration of 3 microg/mL; it increased by 0.5 microg/mL every 60 seconds until all 3 clinical end points were reached, as follows: P1, when patients lost consciousness; P2, when patients failed to show pupillary dilation and skin vasomotor reflex to transcutaneous electric stimulation applied to the upper level of loss of cold sensation; and P3, when patients failed to show pupillary dilation and skin vasomotor reflex to transcutaneous electric stimulation applied to C5. MAIN RESULTS: The effective concentration 50 values for both predicted blood and effect-site propofol concentrations were significantly larger in the 0.2% group than in the 1% group at all end points. The BIS at every end point was significantly smaller in the 0.2% group than in the 1% group. CONCLUSIONS: During combined epidural-propofol anesthesia, unconsciousness and lack of response to noxious stimulation occurred at lower predicted concentrations with 1% epidural ropivacaine than with 0.2% epidural ropivacaine. The results also suggest that the BIS may not be a good indicator when propofol anesthesia is combined with epidural anesthesia.     

Pupillary neuro-ophthalmic analysis in patients with intraocular lenses

Many of the currently used lens implants are iris fixated and change pupillary shape. Concomitant iris surgery and posterior synechiae can make evaluation of pupillary responses difficult in the implanted patient. Pupillary evaluation is critical to neuro-ophthalmic diagnosis, and the presence or absence of a Marcus Gunn pupil is the most common clinical entity likely to be evaluated in the age group of patients with intraocular lenses. A Marcus Gunn pupil can be diagnosed when only one pupil is functional.     

Autonomic effects of epidural and intravenous fentanyl

BACKGROUND: We tested the hypothesis that there is greater suppression ofautonomic reflexes during general anaesthesia when fentanylis administered epidurally than when it is given intravenously. METHODS: Ten volunteers were anaesthetized with desflurane. Noxious stimuliof variable intensity were then delivered by tetanic electricalstimuli. Heart rate, arterial pressure, and pupillary dilationin response to these stimuli defined nociception. Seven of thesevolunteers participated twice using a crossover design: theyreceived i.v. fentanyl on one study day and epidurally on theother. Autonomic responses to alternative tetanic stimuli atL4 and C5 dermatomes were measured every 5 min for 3 hafter fentanyl administration. RESULTS: After a brief redistribution period, plasma fentanyl concentrationswere virtually identical on both days. After stimulation ofthe L4 dermatome only, block of pupillary reflex dilation wasgreater by 47 (22)% after epidural fentanyl compared with i.v.fentanyl. Time to maximal depression of reflex dilation afterL4 stimulation was 41 (13) min. Arterial pressure and heartrate decreased after fentanyl by either route but there wereno differences observed between L4 and C5 stimulations. CONCLUSION: We conclude that during general anaesthesia, epidural fentanylenhances antinociception by a spinal mechanism which can bedetected by pupillary dilation but not by changes in arterialpressure or heart rate.     

Isoflurane, but not mild hypothermia, depresses the human pupillary light reflex

The pupillary light reflex is often evaluated in the perioperative period as a measure of cranial nerve and midbrain integrity. Although surgical concentrations of some anesthetic agents and severe hypothermia qualitatively alter the light reflex, confounding factors frequently present during postanesthetic recovery have not been specifically quantified. We therefore studied 12 volunteers to determine the effects of residual isoflurane concentrations and typical (mild) hypothermia on the human pupillary light reflex. Young, healthy volunteers were assigned to one of three treatments: 1) normothermic isoflurane-oxygen anesthesia; 2) isoflurane-oxygen anesthesia with 2.2 +/- 0.5 degree C central hypothermia; and 3) central hypothermia (1.6 +/- 0.3 degree C) without anesthesia, induced by internal jugular infusion of iced lactated Ringer's solution. In normothermic anesthetized volunteers, the amplitude of the light reflex was depressed 80-90% at end-tidal concentrations greater than 0.5% isoflurane: reflex (percent of control) = 14 - 67.log (percent isoflurane); r = -0.92. In the mildly hypothermic anesthetized volunteers, pupillary responses were not statistically different from those in anesthetized normothermic volunteers: reflex (percent of control) = 16 - 62.log (percent isoflurane); r = -0.97. Hypothermia alone did not alter the magnitude of the light reflex. Our data suggest that mild hypothermia does not depress the light reflex but that isoflurane reversibly depresses the light reflex in a dose-related manner.     

Anesthésie infiltrative tumescente et mastectomie : à propos de six cas

Objective

To assess safety and efficacy of tumescent infiltration of the supraclavicular nerve and the anterior and lateral branches of the intercostal nerves in major breast surgery.

Methods

A retrospective analysis of six selected patients undergoing mastectomy was performed. A mixture composed of 150 mg ropivacaine, 400 mg of lidocaine and 0.5 mg epinephrine diluted in 500 ml Ringer's were administered subcutaneously as follows: 80 ml along the parasternal line from the second to the sixth intercostal space, 80 ml along the mid axillary line from the second to the sixth intercostal space, 80 ml along the infraclavicular line, 80 ml in the space between the pectoralis muscle and the mammary gland and 80 ml in the axilla in case of axillary dissection.

Results

This technique achieved effective analgesia in six patients associated with sedation or light anaesthesia; conversion to general anaesthesia or supplementation with local anaesthesia was not required. No complication was observed. No emesis was noted.

Conclusion

This technique provides adequate peroperative analgesia and is a technically low-risk procedure. Further evaluation of this technique is recommended.     

Vecuronium dose requirement and pupillary response in a patient with olivopontocerebellar atrophy (OPCA)

Purpose

Olivopontocerebellar atrophy (OPCA), a variant of spinocerebellar degeneration (Shy-Drager syndrome), is a systemic degenerative disorder affecting the neurons of multiple nuclei. We investigated the sensitivity to vecuronium and the pupillary responses to various stresses in a patient with OPCA.

Clinical features

A 65-yr-old woman with a six-month history of OPCA underwent a left upper lobectomy for lung cancer under propofol-N₂O anaesthesia. She had symptoms of dysarthria, bulbar palsy, cerebellar ataxia, Parkinsonism, myosis, pyramidal signs and muscular atrophy of the distal extremities. A cumulative dose-response curve for vecuronium was constructed, and pupillary changes in response to various noxious stimuli were evaluated with concomitant recording of the Spectral-Edge-Frequency 90% (SEF90; the frequency below which 90 percent of the EEG power is located). The dose-response curve for vecuronium and the estimated ED₅₀ value (the 50% blocking dose of vecuronium) in this patient with OPCA were almost identical with those of five ASA 1–11 patients (27 μg·kg^?1 vs 31 μg·kg^?1). The pupil size and the SEF90 did not change after tracheal intubation or surgical stimulation in this patient, while in the control subjects (n = 3), these measures increased in response to both stresses.

Conclusions

The absence of pupillary and SEF90 responses to noxious stimuli suggests a sensitivity to propofol and/or central autonomic dysfunction in patients with OPCA. Although the dose requirement of vecuronium in this patient was similar to that of the control patients, the effects of neuromuscular blockers may vary depending on the severity of muscle atrophy.