Surgical Instruments

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Ryles Nasogastric Tube

This is a narrow tube made of non-toxic, medical grade polyvinyl chloride (PVC) or polyurethane. The distal end is coned with steel balls sealed into the tube to facilitate easy insertion. Four lateral eyes along the distal end provide efficient drainage of secretions/fluids. The tubes are marked at 50, 60 and 70 cm from the distal end for accurate placement into the abdomen. The radio-opaque line provided throughout the tube helps radiographic visualisation. The proximal end is provided with a universal funnel connector for easy extension and allows a drain or feeding bag to be connected. Sizes available are 6–18F for adults and 10–14F for children. Ryles tubes are available in packs that have been pre-sterilised with ethylene oxide. They are also available individually in peelable pouch packs.

Nasogastric tubes are used for:

  • aspiration in cases of intestinal obstruction and pyloric stenosis
  • diagnosis of gastrointestinal haemorrhages and acute gastric dilatation
  • enteral feeding and administration of drugs.

To insert a nasogastric tube, position the patient in the lateral position so as not to compress the oesophagus; alternatively, flex the neck in the supine position with pressure on the arytenoid cartilage. Different sizes of Ryles tubes should be kept ready, along with 2% lidocaine gel, sterile gloves and syringes. The nasogastric tube should be well lubricated and passed through one of the nostrils. Once it reaches the throat, the patient should be asked to swallow. The tube then easily enters the oesophagus and stomach. To check the patency of a Ryles tube, push 5–10 mL of air through it using a syringe. Auscultate with a stethoscope on the epigastric area below the xiphisternum or check radiographically to confirm the position. Fix the Ryles tube to the ala with tape.

Complications of nasogastric tubes include discomfort to the patient because of the tube, nasal bleed/epistaxis, damage to the nasal and oesophageal mucosa and gastric reflux, which may cause aspiration.

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Scissors are used for many purposes during a surgical procedure. They come in many different shapes and degrees of sharpness. The purpose of the scissors determines the type needed.

Scissors used for cutting tissue or materials, such as cutting bandages (bandage scissors), cutting sutures, cutting tissue and dissection scissors, have two sharp blades that are screwed together at the centre and are used to cut together.

Surgical scissors, suture scissors, nurse’s scissors:

  1. Multipurpose cutting and dissecting scissors with sharp/blunt, sharp/sharp or blunt/blunt tip configurations; straight or curved; and varying sharpness and lengths. These are used for general cutting of sutures, gauze and other materials. Sharp blades are used to cut tougher tissue and are frequently used for dissection; blunt blades are used for cutting materials such as tubing or gauze.
  2. Operating, or surgical, scissors come in different sizes and are used to cut soft tissue. The blades can be straight or curved and the tips can be blunt or pointed. The type of operation will determine the shape of the cutting blade.
  3. Dissecting scissors are used to separate and differentiate tissues; hence, they are more precise than operating scissors. Iris scissors are small and designed for excising lesions on, or portions of, the iris of the eye.

All types of scissors are sterilised at the same time to avoid loss of sharpness; this is done by autoclaving, plasma sterilisation or chemical sterilisation.

There are two types of operating scissors:

  1. Mayo straight scissors (dissecting scissors, suture scissors, heavy tissue scissors): A versatile instrument for multiple procedures and settings; the straight version is primarily used for cutting surface tissue or sutures, but both curved and straight versions are used interchangeably depending on the procedure and the physician’s preference. These have a standard bevelled blade, a variety of lengths and special features, such as blunt tips.

Mayo curved scissors: These scissors are used in multiple procedures and settings and are versatile; the curved versions are commonly used for cutting or dissecting deep or dense tissue.

Professor Avinash Supe and Dr. Prabhu

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Sengstaken–blakemore Tube (Sb Tube)

This tube is extensively used for controlling variceal bleeding as a temporary treatment or as definitive management prior to endoscopy management.

The tube is made of latex or India rubber and essentially has three channels. The main wide channel is used for gastric lavage. It has a closed tip with multiple openings on the side of the tip. The second channel runs through the main channel, hugging the wall and running parallel to the main channel. It opens distally into a rounded balloon that is placed just proximal to the tip. The proximal end of the second channel opens into a valve adjoining the main channel. Inflating through this valve, the balloon, which is also called a gastric balloon, inflates and, when hitched, compresses the varices against the cardia on its undersurface, temporarily arresting the variceal bleeding. The third channel also hugs the main channel on the opposite side and opens into an oesophageal balloon, which, when inflated, inflates the longitudinal balloon and is meant for tamponade on varices in the oesophagus. The valve to inflate the longitudinal balloon is at the same level as the gastric valve. The tube is calibrated, showing the gastric balloon level and the oesophageal balloon level. The main channel is long enough to reach the pylorus. This tube is only used to arrest bleeding varices in portal hypertension. The main channel is used for gastric washing and to clear blood, which if absorbed distally can lead to hepatic encephalopathy. One modification of an SB tube is known as a Linton’s modification. This modified tube has no oesophageal balloon and the gastric balloon has a capacity of 500 mL; it is used for gastric tamponade only. Another modification is Minnesota’s modification; this has four lumens, three of which are as in an SB tube and the fourth one opens proximal to the oesophageal balloon for aspiration of the oesophagus and so that the saliva is aspirated. Any of these modifications of the balloons are used in a collapsed state and are passed either through the nose or more commonly through the mouth after lubricating well. Traction is given on the tubing over a cricket helmet for pressure tamponade.

It is important to note that, because of recent developments in emergency medical management and endoscopic and radiological techniques in the management of emergency variceal bleeds, the use of these tubes has reduced significantly.

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Laparoscopic Trocar and Cannula

These are called ports as they are portals for entry into the abdominal cavity. They can be of various sizes, such as 5 mm, 6 mm, 10 mm and 12 mm. All trocars have two parts: one is the cannula and the other is the trocar. The tips of the trocar can be conical, blunt or pyramidal in shape. There is an eye at the tip of the trocar for gas to escape; a hiss is used to confirm that the system is inside the abdominal cavity. The cannula has two parts: the shaft and the valve. The valves can be either magnetic or flap valves; this allows unidirectional insertion of the instruments and prevents any leakage of gas after the instruments have been withdrawn. On the top there is an outer washer that does not allow gas to leak from the side of the instrument when operating. The cannula has a Luer lock for attaching gas tubing and to control the flow of gas through the cannula across the abdominal cavity. The trocar is inserted after making an incision on the skin into the abdominal wall; supporting the trocar on the thenar eminence, the middle finger is wrapped around the Luer lock with the index finger pointing towards the sharp end. The trocar is introduced with a screw-like action so that the muscles are split as the trocar and cannula enter the abdominal cavity.

The trocar–cannula system can be disposable, with an in-built knife through which a 0° scope can be introduced. This can be used to gain entry into the abdominal cavity under normal vision, especially in bariatric patients. Five-millimetre ports are generally used for instrumentation, 6-mm ports for instruments as well as for harmonic scalpels and clip applicators, 10-mm ports are used for telescopes and wider instruments and 12-mm ports are used for endo-stapler introduction and for the introduction of mesh into the peritoneal cavity in hernia repair.

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Text and images, unless otherwise stated, are credited to: © Professor Avinash Supe and Dr. Prabhu

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