Visual failure and recovery after thrombosis of a giant carotid ophthalmic aneurysm following vascular bypass and carotid artery ligation.

Thrombosis via Hunterian ligation, with or without high-flow bypass, is the definitive treatment for unclippable giant aneurysms; however, secondary deterioration may occur. We present a 67-year-old woman with an unclippable giant (33mm) carotid ophthalmic aneurysm. High-flow external carotid artery to middle cerebral artery bypass and proximal cervical internal carotid artery Hunterian ligation achieved complete thrombosis. Subsequent expansion of the thrombosed aneurysm created mass effect with hydrocephalus, leading to marked cognitive and visual decline. Aneurysmal decompression led to improved vision and near-normal neurological function.

Modeling of frequency doubling and tripling with measured crystal spatial refractive-index nonuniformities.

Efficient frequency doubling and tripling are critical to the successful operation of inertial confinement fusion laser systems such as the National Ignition Facility currently being constructed at the Lawrence Livermore National Laboratory and the Omega laser at the Laboratory for Laser Energetics. High-frequency conversion efficiency is strongly dependent on attainment of the phase-matching condition. In an ideal converter crystal, one can obtain the phase-matching condition throughout by angle tuning or temperature tuning of the crystal as a whole. In real crystals, imperfections in the crystal structure prohibit the attainment of phase matching at all locations in the crystal. We have modeled frequency doubling and tripling with a quantitative measure of this departure from phase matching in real crystals. This measure is obtained from interferometry of KDP and KD*P crystals at two orthogonal light polarizations.

[Video-assisted thoracoscopic surgery for diagnosis of pulmonary lesions].

23 patients (age 11-66 years) underwent video-assisted thoracoscopic biopsy for diffuse disease or peripheral nodular lesions of the lung. 12 had been previously treated for extrapulmonary malignancy and lung biopsy was done for suspicious metastases. In all cases except 1, lesions were identified and biopsied by thoracoscopy. The postoperative course was easier and shorter as compared to thoracotomy and the mean hospital stay was only 2.5 days. Thoracoscopic lung biopsy is a safe, effective and accurate diagnostic modality for diffuse lung disease and peripheral lesions. It is associated with minimal postoperative pain and discomfort, short hospital stay, early return to normal activity, and gives good cosmetic results.

[First experiences with retroperitoneoscopic lumbar sympathectomy].

We present our initial experience with retroperitoneoscopic lumbar sympathectomy in a series of 5 men aged 25-45 years. 3 suffered from ischemia of the lower limbs due to Buerger's disease, 1 had severe reflex sympathetic dystrophy and 1 had vasculitis with severe, non-healing lower leg ulcers. The right retroperitoneal space was developed with a dissecting balloon-trocar introduced via a small lateral muscle-splitting flank incision. 2 additional 5 mm trocars were used for instrumentation and clipping. L2-L3 or L3-L4 ganglia were resected; mean operating time was 120 minutes. Only oral analgesics were needed for postoperative pain control and oral food intake was resumed the following morning. The procedure was successful in all and was without complications. Mean hospital stay was 2 days. All patients reported significant relief of ischemia or dystrophic pain and/or improvement in trophic changes in the extremities. In the patient with leg ulcers, the largest was successfully covered with a skin graft. The retroperitoneoscopic approach to lumbar sympathectomy successfully combines the advantages of minimal invasive surgery and the reliability and effectiveness of well-established open sympathectomy.

Multicrystal designs for efficient third-harmonic generation.

Efficient frequency tripling of high-fluence, narrow-band laser pulses is routinely accomplished with a doubling crystal and a sum-frequency mixer. The addition of a second mixer can dramatically improve conversion efficiencies for the large bandwidths of interest for inertial confinement fusion. Designs that involve two doublers similarly offer a higher dynamic range of conversion efficiency versus intensity than the usual two-crystal design.

Perturbation theory for electric-field amplitude and phase ripple transfer in frequency doubling and tripling.

A theory is presented for the transfer of a perturbation of the electric field from the input to the output of a frequency converter. The transfer relationship for the field ripple is shown to depend on the plane-wave operating parameters of the converter. Predictions of the theory are shown to be in excellent agreement with full numerical simulations of doubling and tripling and experiments measuring ripple transfer in frequency doubling.

[Preliminary experience with laparoscopic repair of inguinal hernias].

During 1992-1996 we performed 163 laparoscopic hernia repairs in 100 men and 2 women. The mean age was 50.6; and in 61 the operation was bilateral, 66 were by transabdominal preperitoneal approach and 36 by total extra-peritoneal approach. There were only a few minor complications and total recurrence rate was only 4.3%, partly attributable to our learning curve. Laparoscopic inguinal herniorrhaphy reduces postoperative incisional and muscular pain and causes less disruption in the postoperative period than open repair. Return to normal activity and work is faster for laparoscopic than for open repair, but operating room costs are higher (time and equipment). However, economic advantages for the national economy should be considered.

Postischemic intestinal motility in rat is inversely correlated to length of ischemia. An in vivo animal model.

An inverse correlation between postischemic gastrointestinal motility and the length of intestinal ischemia was found in an animal model. Intestinal ischemia was caused without concurrent laparotomy and for a predetermined time period (ischemia time) by pulling on an external nylon thread that was threaded through a double-lumen catheter. This catheter was passed into the abdominal cavity to encircle the superior mesenteric artery. Gastrointestinal motility was determined by the introduction of a color-marked meal into the animal's stomach and the measurement of the proportionate length of the small bowel filled with it (transit index). This simple and reliable animal model can also be used for the evaluation of techniques and pharmacological manipulations aimed at modulation of the effects of intestinal ischemia on intestinal motility and its consequences.

[Laparoscopic colonic resection].

We present our initial experience with laparoscopic colonic resection in 15 patients: adenocarcinoma of the colon, 10 cases, giant villous adenoma (2), arteriovenous malformation (2), and a case of benign stricture. Mean operating time was 190 minutes and there were no intraoperative complications. The margins of resection and number of resected lymph nodes in patients with malignancy were comparable to those in the conventionally operated. Mean postoperative hospital stay was 6.1 days. During a maximum follow-up of 15 months there were no wound or trocar-site recurrences. We conclude that laparoscopic colonic resection is technically feasible and safe. However, its use for treating malignant diseases of the colon needs further study.

Epidural anesthesia accelerates the recovery of postischemic bowel motility in the rat.

BACKGROUND: Intestinal ischemia is associated with derangement of gastrointestinal motility. Uncontrolled clinical observations that bupivacaine injected into the epidural space causes faster recovery of bowel motility after various abdominal operations led us to assess the hypothesis that epidural anesthesia can hasten the recovery of gastrointestinal motility in the immediate postischemic period. METHODS: Gut motility studies were performed in rats in which epidural anesthesia and intestinal ischemia could be initiated without the need to provoke surgical trauma. Epidural lidocaine was compared to epidural saline in their effect on intestinal motility after a 30-min period of bowel ischemia. RESULTS: Total ischemia to the small bowel resulted in pronounced postischemic adynamic ileus as evidenced by only 0.7% of the total length of the small bowel filled with a marker meal at the end of the study period (transit index) compared with 84.4% in the control group. Lidocaine epidural anesthesia caused significantly more rapid resolution of the adynamic ileus (60.3% of the bowel filled with the marker meal vs. 30.9% in the controls in which saline was injected). CONCLUSIONS: Epidural lidocaine compared to epidural saline hastens the recovery of gastrointestinal motility in rats after a 30-min period of bowel ischemia. This effect may be elicited by attenuation of sympathetic efferent inhibitory pathways or by vasodilatation caused by the sympathetic block. These results suggest that lidocaine epidural block not only alleviates pain in situations of ischemic injury to the bowel but may also hasten the recovery from postischemic paralytic ileus.

Plasma concentrations of methadone during postoperative patient-controlled extradural analgesia.

Plasma concentrations of methadone were measured by gas chromatography in 16 patients receiving extradural methadone by continuous infusion for relief of postoperative pain. Venous blood samples were taken after a loading dose of extradural methadone 2 mg and during infusion of 0.46 mg h-1 plus patient-controlled increments of 0.2-1 mg. Mean (SD) plasma concentration of methadone was 9.8 (2.1) ng ml-1 at 15 min; this did not change significantly during the first 2 h, after which it increased gradually to 32.2 (4.6) ng ml-1 (P less than 0.001) at the end of 24 h. The mean quantity of extradural methadone required to produce effective analgesia was 10.3 (1.8) mg during the first 12 h after operation and 6 (1.0) mg for the subsequent 12 h. The mean amount of methadone for effective analgesia on the second day was 7.6 (1.1) mg. No adverse effects were detected during the 2-3 days of methadone therapy. Plasma concentration of methadone increased significantly during patient-controlled infusion of extradural methadone in the first 24 h after operation, suggesting rapid vascular uptake. Systemic activity of the drug contributes to the analgesic effect of extradural methadone.

One-lung high-frequency ventilation in the management of traumatic tear of bronchus in a child.

An 8-yr-old child suffered traumatic bilateral pneumothoraces and a ruptured right main bronchus. Surgical repair of the bronchus was postponed for 18 h after a definite diagnosis was established due to severe hypoxemia and hypercarbia. Only left endobronchial high-frequency ventilation with muscle relaxation corrected this pulmonary dysfunction sufficiently to enable surgical intervention.

Interaction of hypoxia and hypercapnia on cerebral hemodynamics and brain electrical activity in dogs.

The interaction of hypoxic hypoxia, hypercapnia, and mean arterial blood pressure (MABP) was studied in 15 pentobarbital-anesthetized ventilated dogs. In one group of animals (n = 5) hypercapnia [arterial CO2 partial pressure (PaCO2) approximately 50 Torr] was added to both moderate hypoxia and severe hypoxia. Moderate hypoxia [arterial O2 partial pressure (PaO2) = 36 mmHg] increased MABP and cerebral blood flow (CBF) without changes in cerebral O2 uptake (CMRO2). Superimposed hypercapnia increased CBF and MABP further with no change in CMRO2. In another group of animals (n = 5), a MABP increase of approximately 40 mmHg during moderate hypoxia without hypercapnia did not further increase CBF, suggesting intact autoregulation. Thus, during moderate hypoxia, hypercapnia is capable of increasing CBF. Severe hypoxia (PaO2 = 22 mmHg) increased CBF, but MABP and CMRO2 declined. Superimposed hypercapnia further decreased MABP and decreased CBF from its elevated level and further decreased CMRO2. Raising MABP under these circumstances in another animal group (n = 5) increased CBF above the level present during severe hypoxia alone and increased CMRO2. The change in CBF and CMRO2 during severe hypoxia plus hypercapnia with MABP elevation were not different from that severe hypoxia alone. We conclude that, during hypoxia sufficiently severe to impair CMRO2, superimposed hypercapnia has a detrimental influence due to decreased MABP, which causes a decrease in CBF and cerebral O2 delivery.

Epidural capsaicin produces prolonged segmental analgesia in the rat.

The effect of epidural capsaicin injections on the thermal nociceptive threshold of unrestrained freely moving adult rats was examined. Capsaicin solution (1% 0.05 ml, 0.1 ml) was injected in a single dose or in two consecutive doses through an indwelling lumbar epidural catheter. Effects were compared with 1 ml 1% capsaicin injected intraperitoneally. Twelve rats served as sham-treated and vehicle controls. Nociceptive thermal stimuli were brief pulses of CO2 laser radiation directed at three body areas, hind limb, forelimb, and pinna. Capsaicin caused prolonged, segmental thermal analgesia. Maximal nociceptive threshold values in the hind limbs, attained within 24 h of epidural injection, were 2.5 (P less than or equal to 0.006) and 5.3 (P less than or equal to 0.0005) time control values for the 0.05-ml and 0.1-ml doses, respectively. Response thresholds in the forelimbs and pinna were unaffected. Two-stage epidural injection of capsaicin led to a roughly twofold elevation of threshold, as well as prolongation of the analgesia to about 14 days. Intraperitoneal injection of capsaicin resulted in elevation of nociceptive threshold which included all body areas tested. These results indicate that epidural application of capsaicin at the lumbar spinal level produced a profound and long-lasting segmental analgesia.

Research on nonlinear optical materials: an assessment.

The seven papers making up this assessment are based on the Workshop on Nonlinear Optical Materials held in April 1986.