Abstract

Iatrogenic intra-abdominal vascular injury can result from lumbar discectomy via the posterior approach. Although it is well known and documented in the literature, few anesthesiologists have personal experience with this life-threatening incident. Here, we report a patient who sustained perforation of the left internal iliac artery at the L_4-5 level during posterior lumbar discectomy. The patient experienced refractory hypotension with tachycardia at the end of surgery, even with prompt fluid resuscitation and medical treatment. Abdominal distension and tenderness of the left lower abdominal quadrant were also noted. Emergency laparotomy was performed by the consulting vascular surgeon and revealed perforation of the left internal iliac artery. The vascular injury was successfully repaired. It is important that, as anesthesiologists, we must be aware of this potentially fatal complication. Prompt diagnosis and immediate laparotomy to control hemorrhage can result in favorable outcomes.

Keywords

discectomy, lumbar; hypotension; iliac artery, internal;

1. Introduction

Lumbar discectomy is a common surgical procedure for herniated intervertebral disc disease. However, iatrogenic  vascular  injury  can  be  caused  by  acci-dental perforation of the anterior annulus fibrosus and anterior longitudinal ligaments during removal of a herniated disc, with consequential injury to the aorta, inferior vena cava or iliac vessels.^1,2 Damage of  great  vessels  presents  an  immediate  threat  to  life from hemorrhagic shock, which frequently leads to  death  or  serious  complications  such  as  pseu-doaneurysm or arteriovenous fistula. The incidence of this iatrogenicity is fortunately rare, with a rate of  0.01−0.17%.¹⁻⁴  Although  probably  underesti-mated, the reported overall mortality rate of major vascular   injury   in   lumbar   discectomy   without   prompt diagnosis or management exceeds 50%.⁵⁻⁷ This complication is well known and widely docu-mented  in  the  literature.^1,2,8,9  However,  few  an-esthesiologists  or  surgeons  have  encountered  this  misfortune.^2,9 Here, we report a case of left inter-nal iliac artery perforation during lumbar discectomy via the posterior approach. With prompt diagnosis and emergency laparotomy for vascular repair, we avoided a fatal outcome or severe complications. 
Our aim is to raise attention to this rare, but poten-tially dangerous complication and remind anesthe-siologists to be aware of it and, should it occur, it should be handled promptly with due care.

2. Case Report

A 47-year-old, 70-kg woman underwent an elective lumbar discectomy for leftward disc herniation at the L₄₋₅ intervertebral space, which was performed by an orthopedic surgeon at our hospital. Anesthesia was  induced  with  intravenous  fentanyl  (150  μg) and  thiopental  (250  mg).  Rocuronium  (50  mg)  was  administered  to  facilitate  laryngoscopy  and  tra-cheal  intubation  with  a  7.0-mm  cuffed  endotra-cheal  tube.  Right  radial  artery  cannulation  was  established to monitor arterial blood pressure, and a 16-gauge intravenous catheter was inserted into the  left  hand  for  fluid  infusion.  Anesthesia  was  maintained   with   2−3%   sevoflurane   in   oxygen.   Subsequent doses of rocuronium (10 mg) were ad-ministered,  as  required,  to  facilitate  mechanical  ventilation and surgical relaxation.

With  the  patient  in  the  prone  position  on  a  Relton-Hall frame, lumbar discectomy with a pitui-tary rongeur was performed after confirmation of the L₄₋₅ intervertebral space by fluoroscopy. Surgery continued smoothly for 1 hour. Nevertheless, after the disc removal was almost complete, a progres-sive  decrease  in  arterial  blood  pressure  from  120/85  to  65/25  mmHg  was  noted  and  the  end-tidal carbon dioxide decreased from 32 to 20 mmHg within 5 minutes. Intravenous fluid was given at a maximum  rate  and  sevoflurane  was  turned  off  to  allow the patient to wake up. The surgeon was im-mediately notified of the hypotensive episode. The suction bottle was examined, and held only mini-mal blood. The surgeon in charge claimed that the surgical  wound  was  clear  and  the  procedure  was  smooth.  Hypotension  persisted  despite  rapid  col-loid/crystalloid  infusion  and  inotropic  treatment  (dopamine,  10  μg/kg/min),  so  the  surgical  wound  was closed immediately and the patient was placed in a supine position. Transesophageal echocardiog-raphy was performed but did not reveal pericardial effusion,  pulmonary  thromboemboli,  or  any  re-gional wall motion abnormality, except for inade-quate ventricular filling.

Under  the  impression  of  acute  hypovolemia  with  occult  blood  loss,  a  central  venous  catheter  was inserted via the right femoral vein. Repeated blood  gas  analysis  revealed  acute  anemia  (hemo-globin:  6.1  g/dL).  Therefore,  vascular  injury  was  suspected.  Another  central  venous  catheter  was  inserted via the right internal jugular vein for fluid resuscitation. The central venous pressure at this time was 1 mmHg. Abdominal sonography revealed extensive retroperitoneal fluid accumulation and a vascular  surgeon  was  immediately  consulted  be-cause  of  this  event.  Meanwhile,  the  patient  had  emerged  from  anesthesia  and  complained  of  left  lower  abdominal  tenderness.  Emergency  laparot-omy  revealed  a  huge  retroperitoneal  hematoma  formed by an immense surge of blood from a 1-cm-long laceration on the posterior aspect of the left internal  iliac  artery,  just  distal  to  the  bifurcation  of left common iliac artery. The injured left inter-nal  iliac  artery  was  repaired  by  primary  suture.  Eight units of packed red blood cells and 12 units of whole blood were administered during the hypo-tensive episode. The patient was sent to an inten-sive care unit for close observation for 1 day and was discharged 10 days later uneventfully. She was followed-up at our orthopedic clinic for 6 months without neurological or vascular complications.

3. Discussion

Iatrogenic vascular injury during lumbar disc surgery is  a  rare  but  life-threatening  complication.^1−5,8−10 Although  it  is  a  potentially  catastrophic  event,  most surgeons who operate on patients with herni-ated lumbar disc disease do not expect perforation of  the  ventral  disc  space  with  resultant  vascular  injury.^2,10,11 Most of the reported incidents occurred during discectomy at the L₄₋₅ or L₅−S₁ levels. Common iliac arteries, second to inferior vena cava or com-mon iliac veins are very vulnerable to injury at this level because of their anatomical proximity to the operation site and the immobility of these vascular structures.   During   disc   removal,   the   pituitary   rongeur may slip through the anterior longitudinal ligament  and  enter  the  retroperitoneal  space  of  the  abdominal  cavity,  where  vascular  injury  may  occur after a deep bite of the rongeur (Figure 1). Notably, both the anterior annulus fibrosus and the anterior longitudinal ligaments have a self-sealing effect because of their tough and elastic nature.^1,5,12 Bleeding from a vascular injury tends to be limited to  the  retroperitoneal  space  rather  than  being  shed  partially  to  the  operating  space,  which  ex-plains why bleeding in the surgical site is observed in less than 50% of the reported cases.^7,10 Delayed diagnosis or lack of awareness of potentially fatal vascular injuries are due to the absence of bleed-ing  from  the  surgical  site.^5,8  In  our  case,  we  ob-served gradually deteriorating hypotension at the end of the surgery despite the surgeon’s claim of a clear  surgical  wound  and  a  smooth  procedure.  Initially, we did not contemplate this as a sign of vessel  injury  because  the  hemodynamics  were  temporarily stabilized after initial fluid resuscitation and  the  surgeon  was  convinced  that  he  had  not  perforated   the   anterior   longitudinal   ligament.   Nevertheless, the hypotension progressed and per-sisted   after   the   patient   was   turned   supinely.   Moreover,  acute  anemia  (hemoglobin:  6.1  g/dL)  and abdominal tenderness prompted us to consider emergency laparotomy for possible intra-abdominal bleeding, because transesophageal echocardiogra-phy indicated that the hypotension was not due to a  cardiopulmonary  disorder.  Retroperitoneal  fluid  accumulation was confirmed by abdominal sonog-raphy and laparotomy revealed a posterior perfo-ration of the left internal iliac artery and exposed a retroperitoneal crack at the level of the L₄₋₅ in-tervertebral disc. Ewah and Calder⁵ described that arterial injury during lumbar discectomy is inevita-bly fatal without prompt diagnosis and immediate surgical  intervention.  Delayed  recognition  of  an  arterial  injury  can  also  occur  until  the  patient  is  transferred  to  the  recovery  area  because  of  the  tamponade effect of the retroperitoneal hematoma in the prone position.¹² Only the awareness of the anesthesiologist and the receptiveness of the sur-geon operating on the patient for a herniated disc will  manage  such  events  and  prevent  secondary  complications.

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Figure 1 The anatomical proximity of the intra-abdominal vessels and intervertebral discs may facilitate vascular injuries after an incidentally penetrating rongeur. CIA = common iliac artery; CIV = common iliac vein.

Because  arterial  bleeding  from  a  major  vessel  without immediate treatment could lead to a 100% mortality  rate,⁵  any  delay  in  initiating  treatment  or performing irrelevant or inferior diagnostic pro-cedures  may  prevent  effective  resuscitation  and  definite surgical repair. Hildreth and Turcke stated that “no guilt or chagrin should result from a nega-tive  retroperitoneal  exploration  in  a  suspected  vascular  injury”.¹³  Anesthesiologists  should  help  surgeons  to  diagnose  this  acute  cardiovascular event  as  hypovolemia  and  select  the  appropriate  treatment, including inotropic medication and vol-ume replacement to correct the gradually deterio-rating   hypotension.   Abdominal   sonography   is   essential and is effective to confirm the diagnosis¹⁴ without  delaying  appropriate  treatment.  In  addi-tion, a central venous catheter should be inserted via the subclavian or internal jugular vein rather than the femoral vein to prevent extravasation of resus-citative  fluid  or  medications  if  injury  of  a  major  vein adjacent to the operation site is suspected.

The  clinical  manifestations  of  vascular  injury  during discectomy depend on the diameter of the injured  vessel(s)  and  size  of  the  tear(s).  Signs  of  acute  life-threatening  arterial  bleeding  in  the  lower  body  during  surgery  include  transient  (usu-ally  sustained)  and  refractory  hypotension  due  to  hypovolemia,  wide  pulse  pressure,  tachycardia,  decreased  hematocrit,  and  weak  or  undetectable  pulsation in a lower extremity. These signs are sug-gestive  of  massive  bleeding  from  a  major  artery  and emergency laparotomy is required. In patients recovering from anesthesia, abdominal distension, pain,  nausea,  vomiting,  dizziness,  coldness  of  a  lower extremity may be the chief subjective com-plaints. Bleeding from venous injuries during surgery may remain obscure and could stop spontaneously. Such  bleeding  is  often  overlooked  and  the  tran-sient  hypotension  is  often  attributed  to  another  cause. Traumatic vascular injury can also result in the formation of an arteriovenous fistula or pseu-doaneurysm  at  a  later  time,  which  might  be  dis-closed days to years after the disc surgery.^1,2,4,8,9,15 Signs and symptoms of arteriovenous fistula in the lower body include cardiopulmonary disturbances, high-output  heart  failure,  tachycardia,  cardiac  dilatation and hypertrophy, intermittent claudica-tion  and  edema  of  a  lower  extremity,  abdominal  bruit,  adynamic  ileus  and  femoral  nerve  palsy.  Pseudoaneurysm can present as a painful abdomi-nal distension, or a pulsating mass on palpation of the abdomen. Unexpected shock can be the result of a ruptured aneurysm after strenuous exercise or abdominal injury.²

It  is  controversial  whether  modern  techniques  for disc surgery could decrease the incidence of ia-trogenic vascular injury. One case report described vascular injury during microendoscopic discectomy.¹⁶ Even the use of a carbon dioxide laser for lumbar discectomy  could  cause  vascular  injury  after  an  accidental ventral perforation of the disc space.¹⁷

In conclusion, iatrogenic vascular injury related to lumbar disc surgery may be a fatal complication, despite  its  low  incidence.  Anesthesiologists  and  surgeons  should  be  aware  of  this  complication.  Diagnosis is largely dependent on the knowledge of the  pathogenesis  of  this  catastrophic  disorder.  In he  event  of  this  complication,  blood  transfusion  and emergency laparotomy are essential to control the  hemorrhage  and  may  prevent  morbidity  and  mortality.