腹腔镜手术的故障排除【英文讲义】

Troubleshooting in Laparoscopic surgery

Prof. Dr. R. K. Mishra

                               
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What would you do if the following situations occurred during a laparoscopic surgery?(a) The field turns pink or yellow.

1.   White balancing may not have been done initially before inserting the telescope into the abdomen. White balance the camera   should be done after withdrawing it.

2.   There may be wrongly connected RGB cable. The RGB cable should be checked for proper connection.

3.   Low voltage can sometimes alter the colour.

4.   Bile or blood spillage may turn the field pink or yellow due to staining of field. The inadvertent injury to bowel and spillage of bowel content may cause the field to tern yellow.

(b) Sudden black out.

1.   The cause of sudden black out may be due to fused bulb of light source. Switch of light source should be turn to use backup bulb.

2.   There may be disconnected camera or monitor cable. Or the fuse of camera blown due to fluctuation in voltage. The fuse and connection of camera and monitor should be checked.

3.   The tip of the telescope may be touching any object completely so there is no way for light to come out. The telescope should try to re-position.

(c) Poor definition of picture.

1.   The poor picture may be due to soiled lens with blood or other body fluids. It should be cleaned with warm water.   

2.   The camera may not be white balanced or focussed properly. The fine tuning of camera should be tried. The proper white balance of camera is necessary to get a good quality of picture. White balancing of camera should be done by placing the telescope 6 cm away from a complete white gauge piece or tissue paper.

3.   Excessive blood in the operative field resulting in absorption of light and poor field is one of the causes of poor vision of operating field. Proper irrigation and suction should be tried to get a clear view.

What action would you take to control marked intra abdominal bleeding from a trocar site?(a) For immediate control.

• With inserted trocar pressure should be applied on the bleeding site either from outside or using a pledget from within under vision.
• A Foley’s catheter can be inserted and the balloon can be inflated and pulled up creating a tamponade effect.
• A purse string suture can be taken around the incision of trocar and tightened to check the bleeding.
• A clamp can be applied to the port site till the bleeding is controlled
  

(b) For more permanent control.

1.   The bleeding vessel can be sutured from within under vision or controlled with diathermy, or a full thickness bite can be taken externally at the region of the bleeding vessel.

2.   The incision can be extended and the vessel can be found by proper debridement and then bleeding vessel should be ligated.

What action would you take if trocar injury to a large vessel occurs?

1.   The trocar should be left in place. The adequate resuscitative measures should be taken like blood should be at hand for the transfusion.

2.   Urgent laparotomy should be performed and repair of the vessel with adequate exposure should be done.

3.   The help of a vascular surgeon should be asked.

What would you do following a sudden collapse of the patient during an endoscopic procedure? Mention three possible causes for the collapse.

Possible causes for the collapse could be:

1.   Vaso-vagal shock due to peritoneal irritation

2.   CO2 embolism either by direct entry of gas into vessel or through absorption.

3.   Hypercarbia due to systemic CO2 absorption result in respiratory acidosis, pulmonary hypertension leading to cardiac dysrhythmia:

4.   Arrhythmias – AV dissociation, junctional rhythm, sinus bradycardia and asystole due to vagal response to peritoneal stretching.

Insufflation should be stopped and abdomen should be deflated, the patient should be kept in a head down and right up (steep left lateral Trendelenberg position) and 100% O2 should be administered. The blood gas levels should be analysed and corrected accordingly. The gas in the right ventricle should be removed with a central venous catheter if possible. If there is any arrhythmia, Atropine and anti arrhythmic should be given. In case of ventricular fibrillation there may be need of DC defibrillator.

What pressure setting on the Insufflator would you select at the start of a diagnostic laparoscopy in an adult healthy patient?

If general anaesthesia is employed the starting flow rate is set at 1/L, pressure 12 mmHg and volume- 2L.

During diagnostic laparoscopy under local anaesthesia insufflation is begun at a flow rate of 1L/min. Initial low pressure- 2-3mmHg and volume not exceeding 2L.  

(6).What would you do when?(a) High pressure is registered when CO2 is insufflated in the VN before the needle has been placed in the body.

1.      Verres needle may be blocked or

2.      The gas tap may not be opened or the

3.      Gas tube may be kinked.

The tap should be checked for right direction and the needle should be flushed with saline to ensure that it is not blocked. The faulty veress needle should be changed.

(b) High pressures (10 or 15 mm Hg) are obtained during insufflation at 1L/min.

1.      The needle may be in the wrong plane and not in the peritoneal cavity.

2.      Gas tap or needle may be partially blocked

Right plane of insertion of needle should be checked by the saline drop test and negative aspiration test. If the problem continues than needle should withdrawn and re-inserted.

What would you do if after insufflation and on insertion of the telescope;(a) You saw gas in the greater omentum?

If there is gas in the grater omentum the probability is that either the Verres needle or the trocar has entered and insufflated gas into it. There is an increased risk of systemic absorption of CO2 resulting in embolism. The necessary precautions to prevent this should be taken.  Anti thrombotics (Egs.Heparin) should be given, the patient should be tilted head down and left lateral and 100% O2 should be given for inspiration.

(b) Only fat is seen and there is no crepitance in the abdominal wall.

The telescope is probably in the omentum and should be withdrawn and any possible injury of the omental vessel should be checked.

what action would you take when?(a) You are unable to advance trocar into abdomen.

If the trocar is a disposable one confirm whether the blade tip is charged and re- introduce.  Alternatively the tip may get discharged half way. The trocar should be removed recharged and inserted again. If it is a reusable trocar the tip may be blunt in which case it would be better to use a different sharp trocar.

(b) The tip of the obturator is seen entering the abdominal cavity during insertion of a secondary trocar.

The skin incision may be small so the trocar has to be removed, the incision should be extended and the trocar should be re- inserted.

List the safety mechanisms of different types of trocars?

• Blunt (Hasson) trocar- blunt with insertion under direct vision. This type of trocar works on the safety of direct vision.

  
  

• Some disposable trocar have a sharp blade with a spring loaded safety shield which cover the blade tip once the peritoneal cavity is entered. This spring loaded spring mechanism reduces the risk of injury to the underlying viscera by the blade tip.
• Other disposable trocars require charging before insertion and when the tip enters the peritoneal cavity the blade tip retracts inside.
• Reusable trocars have triangular and conical tips. The triangular tips are sharper and tend to cause more vascular injury, the adequate force and fine hand movement is required for its safe use.
  

• Some disposable trocars have a screw shaped cannula, which has to be inserted like a screw, which enables the surgeon to have more control over the force with which he inserts the trocar. These have an additional advantage of not slipping out during the procedure.
• Non bladed obturators are used in some trocars for careful insertion where the problem of charging the blade tip and its patency does not arise.
  

• Visiport is a mechanism in which the telescope is inserted into the cannula and the gun is fired through the abdominal wall visualising each layer until the peritoneal cavity is reached. The trocars are thus inserted under vision layer by layer.
  

• Radially dilating trocars are also available. It has the advantage of entry through a very small incision and then incision can be dilated with the serial dilator.
  

• Ultrasonically activated trocar system is used in some high risk patients. It consists of an ultrasonic generator and a transducer attached to the trocar spike. The sharp pyramidal tip is activated with a frequency of 23.5 KHz and amplitude of 150 Micro m. The trocar fits a 5 mm plastic sheath that is introduced inside a 10mm dilator whose tip is conical.
  

List the factors that contribute to increase the risk of complications with using Verres needle.

-         Faulty needle – dysfunctional spring tip.

-         Wrong method of insertion.

-         Not guarding the needle and not inserting like a dart.

-         Uncontrolled forceful insertion of needle.

-         Wrong angle of insertion i.e. directing straight down instead of towards the pelvic cavity.

-         Excessive force from shoulder rather     than wrist while inserting.

-         Previous abdominal surgery and scarred abdomen.

-         Thin scaphoid individual: risk of deep entry..

-         Spinal deformities kypho-scoliosis.

-         Late pregnancy.

-         Morbid obesity.

-         Organomegaly.

-         Portal hypertension