Structure-Function Relationship in Glaucoma Using Ganglion Cell-Inner Plexiform Layer Thickness Measurements.

PURPOSE: To evaluate the structure-function relationship between ganglion cell-inner plexiform layer (GCIPL) thickness at the macula and 10-2 standard automated perimetry (SAP) in glaucoma and to evaluate the relationship using a recently proposed linear model. METHODS: In a cross-sectional analysis, structure-function relationship was determined in 50 glaucomatous eyes (40 patients, mean deviation: -15.4 ± 7.5 dB) and 21 control eyes (13 subjects, mean deviation: -3.4 ± 3.0 dB), which had undergone 10-2 SAP and GCIPL imaging on the same day. Functional loss was derived from total deviation numerical values on 10-2 SAP and calculated on both a linear (reciprocal of Lambert) and a decibel scale after accounting for the retinal ganglion cell displacement at the macula. Strength of relationship was reported as coefficient of determination (R2) of the linear regression models fitted to the data separately for different sectors. The relationship was also evaluated using a linear model. RESULTS: The R2 for the associations between GCIPL thickness sectors and the corresponding sector SAP total deviation values ranged from 0.19 (for superonasal GCIPL sector) to 0.60 (for average GCIPL thickness) when functional loss was calculated on the decibel scale and 0.16 (for superonasal sector) to 0.54 (for inferior sector) on the linear scale. All associations were statistically significant (P < 0.05). The linear model fitted the data reasonably well. CONCLUSIONS: Significant structure-function associations were found between GCIPL thickness measurements at the macula and the functional loss measured on 10-2 SAP in glaucoma. Best fit was found for the inferior and average GCIPL sector thickness. The linear model was useful to study the structure-function relationship.

Comparing the Structure-Function Relationship at the Macula With Standard Automated Perimetry and Microperimetry.

PURPOSE: To compare the structure-function relationship between ganglion cell-inner plexiform layer (GCIPL) thickness measurements using spectral-domain optical coherence tomography (SDOCT) and visual sensitivities measured using standard automated perimetry (SAP) and microperimetry (MP) at the macula in glaucoma. METHODS: In a prospective study, 45 control eyes (29 subjects) and 60 glaucoma eyes (45 patients) underwent visual sensitivity estimation at the macula (central 10°) by SAP and MP, and GCIPL thickness measurement at the macula by SDOCT. Structure-function relationships between GCILP thickness and visual sensitivity loss with SAP and MP at various macular sectors were assessed using the Hood and Kardon model. To compare structure-function relationship with SAP and MP, we calculated the number of data points falling outside the 5th and the 95th percentile values of the Hood and Kardon model with each of the perimeters. RESULTS: The number of points falling outside the 5th and 95th percentile values of the Hood and Kardon model ranged from 28 (superior sector) to 48 (inferonasal sector) with SAP and 33 (superior sector) to 49 (inferonasal sector) with MP. The difference in the number of points falling outside the 5th and 95th percentile values with SAP and MP was statistically insignificant (P > 0.05, χ(2) test) for all the sectors. CONCLUSIONS: Visual sensitivity measurements of both SAP and MP demonstrated a similar relationship with the GCIPL measurements of SDOCT at the macula in glaucoma.

Minimally invasive trans-portal resection of deep intracranial lesions.

BACKGROUND: The surgical management of deep intra-axial lesions still requires microsurgical approaches that utilize retraction of deep white matter to obtain adequate visualization. We report our experience with a new tubular retractor system, designed specifically for intracranial applications, linked with frameless neuronavigation for a cohort of intraventricular and deep intra-axial tumors. METHODS: The ViewSite Brain Access System (Vycor, Inc) was used in a series of 9 adult and pediatric patients with a variety of pathologies. Histological diagnoses either resected or biopsied with the system included: colloid cyst, DNET, papillary pineal tumor, anaplastic astrocytoma, toxoplasmosis and lymphoma. The locations of the lesions approached include: lateral ventricle, basal ganglia, pulvinar/posterior thalamus and insular cortex. Post-operative imaging was assessed to determine extent of resection and extent of white matter damage along the surgical trajectory (based on T (2)/FLAIR and diffusion restriction/ADC signal). RESULTS: Satisfactory resection or biopsy was obtained in all patients. Radiographic analysis demonstrated evidence of white matter damage along the surgical trajectory in one patient. None of the patients experienced neurological deficits as a result of white matter retraction/manipulation. CONCLUSION: Based on a retrospective review of our experience, we feel that this access system, when used in conjunction with frameless neuronavigational systems, provides adequate visualization for tumor resection while permitting the use of standard microsurgical techniques through minimally invasive craniotomies. Our initial data indicate that this system may minimize white matter injury, but further studies are necessary.

The supraorbital craniotomy for access to the skull base and intraaxial lesions: a technique in evolution.

INTRODUCTION: The supraorbital craniotomy was initially described as a minimally invasive means to target extra-axial lesions in the anterior cranial fossa and sellar/parasellar region. Since its initial description, various modifications have been described. We report our recent experience with this approach (and its modifications) for not only extra-axial but also intra-axial neoplastic pathology. METHODS: Based on patient pathology and anatomic considerations, one of two approaches was performed: supraorbital craniotomy through an eyebrow incision or a combined orbital osteotomy and supraorbital craniotomy through an eyelid incision. RESULTS: This technique was performed on twenty-eight consecutive patients. Intra-axial pathology ranged from anaplastic astrocytoma to metastasis while extra-axial lesions included meningiomas and skull-based metastases. Excellent lesion resection was achieved in the majority of patients. Complications were infection (2 patients) and CSF leak. DISCUSSION: The supraorbital craniotomy and its modifications provide an ideal anterior subfrontal approach through which a wide variety of pathology can be approached. This technique has particular considerations in comparison to traditional cranial base approaches that must be taken into account before it is utilized.

Pilot study: association of traditional and genetic risk factors and new-onset diabetes mellitus following kidney transplantation.

INTRODUCTION: New-onset diabetes mellitus, which occurs after kidney transplant and type 2 diabetes mellitus (T2DM), shares common risk factors and antecedents in impaired insulin secretion and action. Several genetic polymorphisms have been shown to be associated with T2DM. We hypothesized that transplant recipients who carry risk alleles for T2DM are "tipped over" to develop diabetes mellitus in the posttransplant milieu. METHODS: We investigated the association of genetic and traditional risk factors present before transplantation and the development of new-onset diabetes mellitus after kidney transplantation (NODAT). Markers in 8 known T2DM-linked genes were genotyped using either the iPLEX assay or allelic discrimination (AD)-PCR in the study cohort testing for association with NODAT. We used univariate and multivariate logistic regression models for the association of pretransplant nongenetic and genetic variables with the development of NODAT. RESULTS: The study cohort included 91 kidney transplant recipients with at least 1 year posttransplant follow-up, including 22 who developed NODAT. We observed that increased age, family history of T2DM, pretransplant obesity, and triglyceridemia were associated with NODAT development. In addition, we observed positive trends, although statistically not significant, for association between T2DM-associated genes and NODAT. CONCLUSIONS: These findings demonstrated an increased NODAT risk among patient with a positive family history for T2DM, which, in conjunction with the observed positive predictive trends of known T2DM-associated genetic polymorphisms with NODAT, was suggestive of a genetic predisposition to NODAT.

Nematicidal natural products from the aerial parts of Lantana camara Linn.

Lantanilic acid, camaric acid and oleanolic acid possessing nematicidal activity were isolated from the methanolic extract of the aerial parts of Lantana camara Linn. through bio-assay guided fractionation. These compounds exhibited 98%, 95% and 70% mortality respectively against root-knot nematode Meloidogyne incognita at 0.5% concentration. Conventional nematicide furadan showed 100% mortality at this concentration.

Early posttransplant lymphoproliferative disorder presenting with ureteric obstruction in en bloc kidneys.

We describe a female patient who received double pediatric (en bloc) kidney transplants. She presented initially with fever of unknown origin 3 months after transplantation; 5 months after surgery, she presented with obstruction of one ureter followed by obstruction of the other. After 9 months she developed posttransplant lymphoproliferative disorder in both kidneys. To our knowledge, this is the first case report of this disorder occurring in en bloc kidneys and presenting with bilateral ureteric obstruction.

Addition of bicarbonate to plain bupivacaine does not significantly alter the onset or duration of plexus anesthesia.

BACKGROUND AND OBJECTIVES: In an effort to elucidate further the effect of alkalinization of bupivacaine on its anesthetic effect, a study was undertaken using alkalinized and non-alkalinized bupivacaine for lumbar plexus block and comparing the results with those obtained previously with brachial plexus block. METHODS: Thirty consenting adult patients about to undergo lower extremity surgery under regional anesthesia were selected for the study. All of the patients received an inguinal paravascular lumbar plexus block ("3-in-1 block"), along with a sciatic block to allow the anticipated surgery to be carried out. The patients were divided into two groups, one receiving plain "alkalinized" 0.5% bupivacaine; the other receiving plain "non-alkalinized" 0.5% bupivacaine. After each lumbar plexus block, the onset and duration of analgesia and anesthesia of the nerves derived from the lumbar plexus were determined by an independent investigator who was unaware of which solution had been administered. RESULTS: There was no statistically significant difference between the two groups with respect to the onset or duration of anesthesia and analgesia. CONCLUSIONS: The data obtained in the present study indicate that alkalinization of non-epinephrine-containing bupivacaine does not reduce the latency or increase the duration of analgesia or anesthesia after lumbar plexus block. Since most of the studies that do show such an effect of alkalinization were carried out using epinephrine-containing bupivacaine, it is postulated that in those studies alkalinization contributed to the decrease in latency and increase in duration, not so much by providing an increased amount of local anesthetic in the free base form, but by reactivating epinephrine's vasoconstrictor activity, which is inactivated by a low pH.

A complete regional anesthesia technique for cardiac pacemaker insertion.

Sixteen consecutive adult patients scheduled for permanent transvenous cardiac pacemaker insertion received as their total anesthetic the combination of a cervical plexus block and blocks of the second, third, and fourth intercostal nerves using a combination of 1% mepivacaine and 0.2% tetracaine with epinephrine, 1:200,000. This technique consistently provided complete surgical anesthesia of the third cervical (C3) through the fourth thoracic (T4) dermatomes, without anesthesia of the brachial plexus. Anesthesia was adequate for the surgical procedure without the need for supplemental analgesia or anesthesia in all cases. Because fluoroscopy was used routinely for the surgical procedure, it was possible to document that there were no instances of diaphragmatic paralysis or pneumothorax. In contrast to other reports, this technique provides surgical anesthesia that is adequate for all of the approaches used for transvenous pacemaker implantation, except for placement of a battery in an abdominal pouch. There were no serious complications and/or side effects in any of the patients studied.

Brachial plexus block with a new local anaesthetic: 0.5 per cent ropivacaine.

A new local anaesthetic, ropivacaine hydrochloride, was used in a concentration of 0.5 per cent in 32 patients receiving a subclavian perivascular block for upper extremity surgery. One group (n = 15) received 0.5 per cent ropivacaine without epinephrine and a second group (n = 17) received 0.5 per cent ropivacaine with epinephrine in a concentration of 1:200,000. Anaesthesia was achieved in 87 per cent of the patients in both groups in all of the C5 through T1 brachial plexus dermatomes. Motor block was profound with 100 per cent of patients in both groups developing paresis at both the shoulder and hand and 100 per cent developing paralysis at the shoulder. There was a rapid initial onset of sensory block (a mean of less than four minutes for analgesia) with a prolonged duration (a mean of greater than 13 hr of analgesia). The addition of epinephrine did not significantly affect the quality or onset of sensory or motor block. The duration of sensory block was reduced by epinephrine at T1 for analgesia and at C7, C8, and T1 for anaesthesia. The duration of sensory block in the remaining brachial plexus dermatomes as well as the duration of motor block was not effected by epinephrine. There was no evidence of cardiovascular or central nervous system toxicity in either group with a mean dose of 2.5-2.6 mg.kg-1 ropivacaine.

Protection from stress of tracheal intubation with midazolam-sufentanil neuroleptanalgesia.

Although diazepam has been shown to reduce the stress response, the protective effect of midazolam, a newer benzodiazepine from a stressful event, tracheal intubation, has not been studied as yet by catecholamine assays in patients undergoing coronary artery bypass surgery, who also receive intravenous sufentanil as a component of the neuroleptanalgesic technique. Therefore, we evaluated the influence of midazolam in combination with sufentanil on the plasma free catecholamines before and after midazolam, after sufentanil and pancuronium and before and after intubation in 15 adult patients undergoing coronary artery surgery. After routine premedication, midazolam 0.14 +/- 0.01 mg.kg-1 i.v. was given over 1 min followed 5 min later by sufentanil in incremental i.v. doses of 1.5 micrograms.kg-1 to a total pre-intubation dose of 4.0-5.0 micrograms.kg-1 injected in 10 min. The incremental doses of sufentanil were given when a greater than 15 per cent increase in rate-pressure product occurred. One min after the initial dose of sufentanil, pancuronium 0.1 mg.kg-1 i.v. was given to provide muscle relaxation. Midazolam administration per se caused a significant decrease in systolic and diastolic blood pressures with a concomitant reduction in systemic vascular resistance. Sufentanil reduced the left ventricular stroke-work index. Tracheal intubation, a strong stressor during anesthesia, elicited no increase in catecholamines and/or adverse hemodynamic responses in contrast to a marked increase in plasma catecholamines routinely observed in patients anesthetized by the commonly used technique of intravenous barbiturates in combination with succinylcholine.

Haemodynamic stability with midazolam-ketamine-sufentanil analgesia in cardiac surgical patients.

Although sufentanil in high doses may result in deep coma sufficient to conduct coronary-bypass surgery painlessly in patients, its side effects, e.g., bradycardia and hypotension, may lead to complications in some patients. Since ketamine causes central sympathetic stimulation, we attempted to counteract the vagomimetic effects of sufentanil by ketamine. Anaesthesia was induced in patients, (n = 15), for elective coronary artery-bypass surgery with 0.12 mg.kg-1 midazolam IV, followed by 1 mg.kg-1 ketamine and 0.6 micrograms.kg-1 sufentanil IV eight minutes later. Subsequently, pancuronium 0.1 mg.kg-1 was given to facilitate tracheal intubation. Three minutes later, the trachea was intubated, and ketamine 1 mg.kg-1.hr-1 IV infusion was started. Incremental doses of 0.6 micrograms.kg-1 sufentanil were given whenever a greater than 15 per cent increase in rate-pressure product was observed. The mean +/- S.E.M. dose of sufentanil before cardiopulmonary bypass was 6.5 +/- 0.6 micrograms.kg and 9.1 +/- 0.9 micrograms.kg for the entire procedure. Although midazolam alone caused reductions in systolic BP, SVR and LVSWI, other haemodynamic variables were not altered. The administration of this anaesthetic technique caused no clinically important adverse haemodynamic changes and/or ST-segment changes and prevented the adverse haemodynamic changes caused by intubation, skin incision, sternotomy and periaortic dissection. Adequate analgesia, complete amnesia and early recovery of wakefulness were observed.

pH adjustment schedule for the amide local anesthetics.

Several studies have indicated that the addition of sodium bicarbonate to solutions of local anesthetics to raise the pH closer to the pKa shortens the latency, increases the intensity, and prolongs the duration of the resultant neural blockade. However, the addition of too much bicarbonate will cause precipitation, and this may result in the injection of particulate free base along with the solution. The present study was carried out to determine the maximal amount of sodium bicarbonate that can be added to each of the amide local anesthetics without the formation of a precipitate, and, thus, to construct a pH adjustment schedule to simplify the alkalinization of local anesthetics in clinical practice.

Comparison of the hemodynamic effects of midazolam and diazepam in patients with coronary occlusion.

Midazolam is gradually replacing diazepam in neuroleptanalgesia with fentanyl and sufentanil because of its greater water solubility, greater hypnotic potency, shorter half-life, lack of pharmacologically active metabolites and low incidence of thrombophlebitis. In order to substantiate midazolam as being as safe and effective as diazepam in cardiac patients with severe coronary occlusion, hemodynamic measurements were made before and 10 min after completion of intravenous injection of 0.2 mg/kg i.v. midazolam (n = 45) and 0.4 mg/kg i.v. diazepam (n = 30), the doses which are identical to those used in patients undergoing cardiac catheterization. All 75 patients were spontaneously breathing 40% O2 in air. No positional changes or stimulation of patients were allowed before and during the study. Of hemodynamic variables, systemic systolic blood pressure was significantly reduced by both midazolam and diazepam. Midazolam also caused significant reduction in systemic vascular resistance with reduction in diastolic pressure and left ventricular stroke work index. No changes in heart rate, systolic and diastolic pulmonary artery pressures, cardiac output and index, stroke volume and index, pulmonary vascular resistance, right ventricular stroke work index and rate pressure product were observed following either midazolam or diazepam. No statistically significant differences were observed in any hemodynamic variable between those patients receiving midazolam or diazepam. It is concluded that midazolam is as safe as diazepam in cardiac patients with coronary obstruction.

Haemodynamic stability with midazolam-sufentanil analgesia in cardiac surgical patients.

Since the administration of both diazepam and midazolam are claimed to cause adverse haemodynamic effects following fentanyl or sufentanil intravenous injection, we evaluated the effectiveness and safety of the reverse sequence, (midazolam-sufentanil) on haemodynamic variables, adequacy of analgesia, amnesia and recovery in 15 adult patients undergoing coronary artery surgery (with a mean +/- SEM ejection fraction of 0.41 +/- 0.03). After routine premedication, midazolam 0.14 +/- 0.01 mg.kg-1 IV was given over one min followed 5 min later by sufentanil in incremental IV doses of 1.5 micrograms.kg-1 to a total pre-intubation dose of 4.0-5.0 micrograms.kg-1 injected in 10 min. One minute after the initial dose of sufentanil, pancuronium 0.1 mg.kg-1 IV was given in 30 seconds. The incremental doses of sufentanil were based on a greater than 15 per cent increase in rate-pressure product. The mean dose of sufentanil before cardiopulmonary bypass was 9.6 +/- 2.1 micrograms.kg-1 and 13.9 +/- 1.3 micrograms.kg-1 for the entire procedure. A significant decrease in systolic and diastolic blood pressures occurred after midazolam administration which was sustained until sternotomy. A significant reduction in systemic vascular resistance occurred following midazolam. Sufentanil reduced the left ventricular stroke-work index. Tracheal intubation, skin incision and sternotomy elicited no adverse haemodynamic responses. Adequate analgesia, complete amnesia and early recovery of wakefulness were observed.

Nalbuphine as an analgesic component in balanced anesthesia for cardiac surgery.

The efficacy and safety of nalbuphine hydrochloride as an IV analgesic used in combination with pretreatment and supplemental doses of diazepam with and without N2O were assessed in 15 patients scheduled to undergo aortocoronary bypass (n = 11) or valve replacement surgery (n = 4). The loading infusion of 3.0 mg/kg nalbuphine given in 20 min 5 min after conclusion of IV injection of 0.4 mg/kg/5 min diazepam caused no significant changes in systolic or diastolic systemic and pulmonary arterial blood pressures or in heart rate, cardiac index, stroke index, systemic and pulmonary vascular resistance, or right and left ventricular stroke work index. After the initial 1-hr loading infusion of 6.66 +/- 0.89 mg/kg nalbuphine (mean +/- SE), additional nalbuphine infusion maintenance doses of 4.73 +/- 0.77, 1.87 +/- 0.31, 2.16 +/- 0.23, 1.65 +/- 0.22, and 2.35 +/- 0.44 were used in the subsequent hourly periods to maintain a pain-free state throughout surgery. Hemodynamic changes during the three most stressful periods, tracheal intubation, skin incision, and sternotomy, were not statistically significant. Normal plasma catecholamine and cortisol levels indicate that these patients experienced neither stress nor pain during the maintenance of anesthesia. Nalbuphine caused no significant histamine release. All patients had uncomplicated maintenance of and emergence from anesthesia.

Diazepam causes no adverse cardiocirculatory effects in cardiac patients.

The effects of diazepam on hemodynamic measures and catecholamine levels were studied in 25 patients before administration of any other anesthetic or analgesic agent, for coronary artery bypass graft surgery. The patients were spontaneously breathing 40% oxygen in air, and no postural changes or surgical manipulations were allowed before or during the study. Before and ten minutes after completion of the intravenous infusion of 0.4 mg/kg of diazepam over five minutes, the following hemodynamic variables were determined: direct radial artery pressure, pulmonary artery pressure, central venous pressure, cardiac output by thermodilution in triplicate via a balloon-tipped pulmonary artery catheter and electrocardiograms. Norepinephrine, epinephrine, and dopamine levels were determined by liquid chromatography. Significant (P less than 0.05) reductions in pulmonary artery systolic pressure, systolic systemic blood pressure, and epinephrine levels were observed after diazepam administration. No other hemodynamic changes were statistically significant. Thus diazepam alone caused no adverse hemodynamic or endocrine effects in cardiac surgical patients. It is concluded that the use of diazepam is not contraindicated in cardiac patients with reduced myocardial oxygen supply as a consequence of coronary sclerosis.

Midazolam causes no adverse hemodynamic effects in cardiac patients.

The effects of midazolam on hemodynamic measures were evaluated in 30 patients scheduled for cardiac surgery. The patients were spontaneously breathing 40% oxygen in air and no postural changes or surgical manipulations were allowed before or during the study. Before and 10 minutes after completion of the intravenous infusion of 0.2 mg/kg of midazolam, the following hemodynamic variables were determined: direct radial artery pressure, pulmonary artery pressure, central venous pressure, cardiac output by thermodilution in triplicate via a Swan-Ganz pulmonary artery catheter, and electrocardiograms. Significant (P less than 0.05) reductions in systolic systemic blood pressure, systemic vascular resistance, systemic diastolic blood pressure, and left ventricular stroke work index were observed after midazolam administration. No other hemodynamic changes were statistically significant. Thus midazolam per se caused no adverse, but rather favorable, cardiocirculatory effects since it reduced cardiac work without altering cardiac contractility.