Laser surgery in the larynx. Early clinical experience with continuous CO 2 laser.

A novel microfluidic device that can selectively and specifically isolate exceedingly small numbers of circulating tumor cells (CTCs) through a monoclonal antibody (mAB) mediated process by sampling large input volumes (≥1 mL) of whole blood directly in short time periods ( 97%) by designing capture channels with the appropriate widths and heights. The isolated CTCs were readily released from the mAB capturing surface using trypsin. The released CTCs were then enumerated on-device using a novel, label-free solution conductivity route capable of detecting single tumor cells traveling through the detection electrodes. The conductivity readout provided near 100% detection efficiency and exquisite specificity for CTCs due to scaling factors and the nonoptimal electrical properties of potential interferences (erythrocytes or leukocytes). The simplicity in manufacturing the device and its ease of operation make it attractive for clinical applications requiring one-time use operation.

Highly Efficient Circulating Tumor Cell Isolation from Whole Blood and Label-Free Enumeration Using Polymer-Based Microfluidics with an Integrated Conductivity Sensor

The aims of this paper are to briefly describe laser physics, the types of lasers currently available for use on soft tissues focusing primarily on CO2 and Nd:YAG laser energies, the histological effects of lasers on oral tissues, laser safety, the clinical applications of lasers on oral soft tissues, and future directions. Of the two types of lasers currently available for dental applications, both the CO2 and Nd:YAG lasers can be used for frenectomies, ablation of lesions, incisional and excisional biopsies, gingivectomies, gingivoplasties, soft tissue tuberosity reductions, operculum removal, coagulation of graft donor sites, and certain crown lengthening procedures. The advantages of lasers include a relatively bloodless surgical and post-surgical course, minimal swelling and scarring, coagulation, vaporization, and cutting, minimal or no suturing, reduction in surgical time, and, in a majority of cases, much less or no post-surgical pain. CO2 lasers, compared to Nd:YAG are faster for most procedures, with less depth of tissue penetration and a well-documented history. There have been recent reports on the use of the Nd:YAG laser for periodontal scaling, gingival curettage, and root desensitization, but further research needs to be conducted. Both the CO2 and the Nd:YAG laser have limited use in conventional flap therapy.

Current Status of Lasers in Soft Tissue Dental Surgery

The possibility of revascularizing the myocardium with high-energy laser was investigated based on the finding that the laser beam could produce small channels in the tissue of the myocardium that were devoid of debris and scarring. The technique was investigated in 4 groups of 6 mongrel dogs each. In 3 of the groups, the left anterior descending (LAD) coronary artery was ligated above the first diagonal branch and the myocardium was treated with the laser energy according to the protocol of that group. In the fourth control group, the LAD artery was ligated but the myocardium was not subjected to laser treatment. In the first 3 groups, the myocardium was protected by the channels produced by the application of the laser energy. The animals were subsequently sacrificed at various intervals. In the control group, all of the animals died within 20 minutes of ligation of the artery. At autopsy, the epicardial sites of the channels created by the laser were clearly visible and a lack of charring in the channels was demonstrated. The penetration through the endocardial surface could be demonstrated. Microscopically, the channels were patent and endothelialized. It is concluded that the channels created in the myocardium effectively helped to protect the myocardium from acute coronary artery occlusion in this model in dogs.

Revascularization of the heart by laser

Brief pulses of Laser emitted radiant heat were used to induce cutaneous painful sensations in human volunteers. Accurate timing of the stimuli permitted recording of scalp averaged evoked potentials. A late negative-positive component of the EP which correlated in amplitude with the subjective sensation was abserved in four subjects. The latency of this component (130–160 msec) correlated with stimulus intensity.

Evoked cerebral responses to noxious thermal stimuli in humans.

The characteristics of CO2 lasers that render them interesting for surgical applications are reviewed. An instrument consisting of an integrated CO2 laser and beam manipulator, designed specifically for surgical research work, is descirbed. Operational characteristics of the instrument relevant to such work are reported. An accessory for endoscopic surgery is described and instrumentation for microsurgery is discussed. Surgical researches now in progress with this instrument are mentioned.

A CO2 laser for surgical research.

In preliminary studies, the carbon dioxide laser with a specially devised surgical manipulator has been shown to have a great potential for surgical application, especially in neurosurgery. It can incise nearly all tissues, bore or drill, excise and vaporize as needed. Cancers, even when ulcerated and infected, can be made to disappear by vaporization or portions of neoplasms can be excised with the laser beam. Experimental, transplantable animal tumours and one human brain tumour have already been treated with this laser. Rapid cleaning of infected, scarred decubitus ulcers, followed by immediate placement of free or pedicle grafts is suggested as a means for eliminating the weeks of pre-operative preparation ordinarily necessary in such cases. Minimal lesions can likewise be made for functional neurosurgery or for other purposes. When used in conjunction with the operating microscope control is correspondingly increased. Action by the laser is swift, gentle and easily controlled. Damage from the beam can be confined to within a millimetre of its application. Small blood vessels are readily coagulated by the CO2 laser making oozing surfaces easier to handle. The disadvantages include the inability of the CO2 laser beam to traverse any tissue, including the transparent media of the eye, without damage. Deep structures must, therefore, be surgically exposed. Ignition of flammable materials, such as drapes, and damage to personnel must be prevented but this can be done quite simply. Among the many problems which remain are those related to the total removal of cancers without causing undue damage to surrounding structures and those related to wound healing especially for skin. The problem of bleeding from large vessels needs further study. A method for controlling the vaporization of neoplasms, using radioactive monitoring of the smoke produced, is suggested.

Experimental studies with the carbon dioxide laser as a neurosurgical instrument.

The scope and techniques of surgery become progressively more complex. However, the tools of the surgeon are relatively few, and they are chiefly mechanical: traditional scalpel, scissors, saws, and drills. More or less recent innovations are the electrical high-frequency knife (Bovie), which provides cauterization when used to cut or ablate tissue, and freezing techniques and ultrasound energy, which are used for specialized applications. Though not strictly considered surgical tools, penetrating ionizing X-rays and γ-rays have vast applications in cancer therapy.

Lasers in Surgery

Thirty-two conditioned 15-18 kg dogs underwent laparotomy, heparinization, left lateral hepatic lobe injury and subsequent partial left lateral hepatic lobectomy. The hemostatic capabilities of the surgical scalpel combined with suture ligatures and stay sutures, the Bovie, and the CO2 laser were compared. The CO2 laser proved significantly more effective in achieving hemostasis both in comparison to the Bovine and the surgical scalpel combined with classical methods. The postoperative mortality utilizing the Bovie was 11%, the scalpel 30% and the laser 23%. Two of the three laser deaths were related to a bulky laser delivery system which can be redesigned. Postoperative laboratory evaluation revealed that SGOT, LDH, alkaline phosphatase, total protein, albumin and hemoglobin levels were altered in the postoperative period but returned to normal levels in uniform fashion in all groups. There was no statistical difference between various surgical modalities with regard to these parameters. The white blood count was significantly lower in laser dogs when compared to the other two groups. Other laboratory parameters were unchanged. Damage to liver tissue may be less extensive when the laser is utilized as opposed to the Bovie or stay suture methods of hemostasis and healing is equally good. The CO-2 laser is considered a valuable ancillary tool in hepatic resection and clinical evaluation is warranted.

Bredemeier Hc

Papers

A CO2 laser for surgical research.

Experimental studies with the carbon dioxide laser as a neurosurgical instrument.

Lasers in Surgery

Laser surgery in exsanguinating liver injury.

Experimental carbon dioxide laser surgery of the vocal cords.