Three years'' anaesthetic experience with the Groningen Nd YAG laser coagulation technique

The use of the Neodymium YAG Laser technique in the palliative treatment of tracheo-bronchial tumors in 47 patients is described and the merits of the coagulation and anaesthetic techniques are discussed.     

Estimating the incubation time distribution and expected number of cases of transfusion-associated acquired immune deficiency syndrome

The number of cases of transfusion-associated acquired immune deficiency syndrome (TA-AIDS) that will be seen over the next few years is difficult to estimate, because of the uncertainty about the number of persons infected with the human immunodeficiency virus (HIV) via blood transfusion and about the duration of the incubation period from HIV infection via transfusion to diagnosis of AIDS. Presented here are a mathematical model and nonparametric and parametric statistical analyses of recent data on TA-AIDS that indicate clearly the existing estimability problems. The methods provide short-term projections of new TA-AIDS cases to be reported; the results suggest about 1100 new cases to be reported in the United States between July 1988 and June 1989 and about 1500 more between July 1989 and June 1990. Estimates of the number of eventual TA-AIDS cases to be seen are considerably more uncertain and require additional assumptions about the incubation distribution. Under the assumption that the probability of an infected person developing AIDS within 8 years of infection is 0.40 (an estimation derived from cohort studies in homosexual men and hemophiliacs), parametric and nonparametric analyses give, respectively, point estimates of 14,300 and 15,000 for the number of eventual cases of AIDS (in the age group 13-69) attributable to infection by blood transfusion prior to July 1985. The parametric analysis gives a corresponding 95 percent confidence interval.     

Relationship between visual field loss and contrast threshold elevation in glaucoma

Background  

There is a considerable body of literature which indicates that contrast thresholds for the detection of sinusoidal grating patterns are abnormally high in glaucoma, though just how these elevations are related to the location of visual field loss remains unknown. Our aim, therefore, has been to determine the relationship between contrast threshold elevation and visual field loss in corresponding regions of the peripheral visual field in glaucoma patients.     

Epiphyseal ossification centers in the assessment of fetal maturity: sonographic correlation with the amniocentesis lung profile

The epiphyseal ossification centers of the distal femur (DFE) and proximal tibia (PTE) appear and enlarge during the third trimester of pregnancy. Late in the third trimester, the epiphysis of the proximal humerus (PHE) begins to ossify in some fetuses. Using the amniocentesis lung profile to determine the value of sonographic epiphyseal visualization as a predictor of pulmonary maturity, we studied 50 fetuses prospectively and compared the sonographic epiphyseal findings with results from the amniocentesis lung profiles. Nine fetuses with a visible PHE had a mature amniocentesis lung profile (accuracy of positive prediction = 100%), and then fetuses with an immature amniocentesis lung profile had no visible PHE (conegativity = 100%). Fetuses in which the combined DFE and PTE diameters were greater than 11 mm or in which the DFE and the PTE diameters were similar in size (DFE less than or equal to 1 mm larger than PTE) also yielded positive results. Copositivity and accuracy of prediction of an immature amniocentesis lung profile, on the other hand, were low (22%-25%) for the same epiphyseal parameters. These data suggest that antenatal visualization and measurement of the epiphyseal ossification centers of the fetal knee and shoulder may help to identify fetuses that would have a mature amniocentesis lung profile.     

Automated regular boluses for epidural analgesia: a comparison with continuous infusion

BACKGROUND: Intermittent epidural bolus dosing is a method of drug delivery that can prolong the duration of labour analgesia induced by a combined spinal epidural (CSE). In this randomized, double-blinded study, we compared the analgesic efficacy of two drug delivery systems: regular intermittent epidural boluses and continuous epidural infusion and assessed the incidence of breakthrough pain after CSE. METHODS: With the approval of the Hospital Ethics Committee, we recruited 60 parturients into this randomized controlled trial. A CSE was performed with intrathecal fentanyl 25 mug in all patients. The parturients were then randomly allocated into two groups. The infusion group received a continuous epidural infusion of levobupivacaine 0.1% with fentanyl 2 microg/mL at a rate of 10 mL/h. The bolus group received 5-mL epidural boluses every half hour. The sample size was computed to detect a 40% reduction in the rate of breakthrough pain. RESULTS: The bolus group had a lower incidence of breakthrough pain than the infusion group (10% vs. 37%, P < 0.05). The bolus group also had significantly higher satisfaction scores for labour analgesia: 97+/-8 (mean+/-SD) vs. 89+/-7 (P < 0.05). CONCLUSION: Automated regular bolus delivery of epidural analgesia when compared with continuous infusion decreased the incidence of breakthrough pain and increased maternal satisfaction. In a busy obstetric unit, this may also serve to decrease the anesthetists' workload.     

The median effective dose of intrathecal hyperbaric bupivacaine is larger in the single-shot spinal as compared with the combined spinal-epidural technique

The combined spinal-epidural technique (CSE) has been associated with prolonged motor recovery and more frequent arterial hypotension as compared with a single-shot spinal (SSS) technique. We determined the median effective dose (MED) of intrathecal hyperbaric bupivacaine for CSE and SSS by using the up-down sequential allocation technique. Sixty male patients were randomly allocated to receive intrathecal administration through an SSS or CSE technique. Needle insertion occurred at the L3-4 interspace in all patients. In SSS, 9.5 mg of hyperbaric bupivacaine was administered through a 27-gauge Whitacre spinal needle. In CSE, a 17-gauge Tuohy needle with 4 mL of air was used to locate the epidural space, through which a 27-gauge Whitacre spinal needle was introduced and 7.0 mg of hyperbaric bupivacaine was administered. The dosing adjustment was 0.5 mg. A "successful" outcome was arbitrarily defined as sensory anesthesia at or above the T6 dermatome lasting for 60 min. A "success" resulted in a 0.5-mg decrement, whereas a "failure" resulted in a 0.5-mg increment in the next patient. There were 13 successes in both groups. The MED of bupivacaine was 9.18 mg (95% confidence interval, 8.89-9.47 mg) for CSE as compared with 11.37 mg (95% confidence interval, 10.88-11.86 mg) for SSS (P < 0.001). CSE required 19.3% (95% confidence interval, 14.9%-23.6%) less local anesthetic to achieve the defined clinical target. We found significant discrepancies in the MED of hyperbaric bupivacaine between the two techniques. Under similar clinical conditions, a 20% decrement in the dose of bupivacaine may be warranted whenever CSE is intended in place of SSS.