Research Papers

An Infant Surgical Table for Laser Photocoagulation: Design and Development

[+] Author and Article Information
Kimberly Ryland

 Stryker Endoscopy, 5900 Optical Ct., San Jose, CA 95138kimberly.ryland@stryker.com

Carl A. Nelson1

 University of Nebraska-Lincoln, Department of Mechanical Engineering, University of Nebraska Medical Center, Department of Surgery, Center for Advanced Surgical Technology, N104 WSEC, Lincoln, NE 68588cnelson5@unl.edu

Thomas Hejkal

 University of Nebraska Medical Center, Department of Ophthalmology and Visual Sciences, Omaha, NE 68198-5540twhejkal@unmc.edu


Corresponding author.

J. Med. Devices 2(3), 031003 (Sep 04, 2008) (8 pages) doi:10.1115/1.2974981 History: Received June 02, 2008; Revised June 11, 2008; Published September 04, 2008

Retinopathy of prematurity, caused by abnormal blood vessel development in the retina of premature infants, is a leading cause of childhood blindness. It is treated using laser photocoagulation. Current methods require the surgeon to assume awkward standing positions, which can result in injury to the surgeon if repeated often. To assist surgeons in providing quality care and prevent occupational injury, a new infant surgical table was designed. The engineered solution is an attachment to a standard surgical table, saving cost and space. The adjustable height and tilt provided by the standard table combined with the 360 deg rotation designed into the attachment allow the surgeon to sit during surgery. The infant table incorporates several novel features. Critical cords and tubes are routed through an aperture at the center of the attachment to avoid pulling and kinking. A four-bar locking mechanism allows easy attachment to standard medical railing. A straight-line mechanism provides positive locking of the rotation, allowing precise positioning of the infant. Load-deflection testing was carried out using an infrared camera tracking system, and expert feedback was also obtained in a clinical setting to ascertain proper function. Strength testing showed acceptably small deflections and stresses under representative loading conditions. Benchtop and clinical testing of the infant table have demonstrated that it reliably and safely meets the design objectives. The device also shows promise for use in other infant or pediatric treatment and in small-animal veterinary practice.

Copyright © 2008 by American Society of Mechanical Engineers
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Figure 1

Effective infant surgical table requires 4-DOF

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Figure 2

(a) CAD drawing of the new infant surgical table. (b) The new infant surgical table in surgery.

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Figure 3

Placing the support bar over the railing (infant table held at an angle)

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Figure 4

Toggle clamp: (a) toggle clamp designed to be locked with one hand; (b) open toggle clamp configuration shown in dashed lines, locked position in dark lines; (c) a locking pin prevents accidental unlocking of toggle clamp; (d) parts: handle, base (contiguous with the support bar), turnbuckle adjustment, and jaw; (e) nomenclature of toggle clamp.

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Figure 5

Mechanical advantage of toggle clamp from unlocked position (15.5 deg) to locked position (−4.5 deg)

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Figure 6

(a) Estimate of bending load induced in base link of toggle clamp. (b) Estimate of strain energy in toggle clamp based on bending model.

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Figure 7

Straight-line braking mechanism prevents table rotation

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Figure 8

Graphical synthesis of approximate straight-line mechanism–deviation from a straight-line pull of 0.02 mm

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Figure 9

Lines routed through clamps and center of table

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Figure 10

Software screen shot of infant table markers during testing. Approximate field of view—x: [320–2900 mm]; y: [−1500 to 1500 mm]; z: [0–1200 mm].

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Figure 11

(a) Starting positions (or no weight positions) of each weight test compared to the original position. Note the changes due to accumulated inelastic deflections caused by applying successive weights to the prototype table. (b) Inelastic deflections occurring with successive weight. (c) Elastic deflections occurring with successive weight.



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