Patient was a 62 year old female. Past medical history included hypertension, on medication. Scheduled for a thoracic laminectomy under GA to treat spinal stenosis with some underlying spinal cord compression on imaging.
Patient had presented and admitted to the hospital hypertensive and received an additional dosage of hypertensive medication. As a result, on the morning of the surgery, the last recorded BP reading, before induction, was 98/62. Patient inducted with Midazolam, Lidocaine, Fentanyl, Propfol, Rocuronium and continued on Sevoflurane. while undergoing SEEP monitoring.
No measures to increase BP before induction. No arterial line in place. Upon induction, next BP reading was 56/33., followed by 53/28, 52/41 and 59/40 with a HR in the 40's.resulting in profound hypotension over a roughly 15 minute period. In that period, two low doses of Ephedrine administered. BP eventually stablized, and surgery proceeded without complications. Patient awoken post-op with decreased LE function/sensation. Patient taken back to the OR for exploration, but no swelling/hematoma found at surgical site. Deficits are permanent.
Issues include adequacy of pre-anesthesia assessment and optimization of BP before induction; Choice of induction agents and dosages in light of hypotension; and adequacy of response to severe, extended hypotension.
.
Files:
Q: What medications does the patient take at home to control her hypertension?
A: My recollection is Benicar, 12.5 mg., b.i.d.
Q: Was this the medication that was given preoperatively?
A: Olmesarten, 40 mg,, two tabs, Hydrocholorthiazide, 25 mgs., once
Q: What were the baseline readings for neuromonitoring prior to starting the surgery?
A: in the record, the SEEP was described as delayed latency and small amplitude of the lower extremities, which persisted throughout the procedure. Of, note, IOM began AFTER the period of hypotension.
Q: How high was the initial BP in preop?
A: In the 24 hours before surgery, the systolic ranged between 140 and 180 and the diastolic between 80 and 95. After the aforementioned increased BP medications were given, the patient's BP had decreased to 90/59
Q: 1. How was the patient positioned 2. How were evoked potentials obtained and monitored 3. Most importantly, did a post-op MRI establish the presence of a spinal cord infarction (or ischemia)
A: —
Q: What was the patient’s blood pressure on admission to the hospital? What anti-hypertensive medication was administered pre-operatively (medicine/dose/time).
A: —
Do you believe there might have been medical error?
Undertreated and unrecognized hypotension lead to the patient's problems.
Do you believe there might have been causation (i.e. the medical error resulted in an injury)?
There was likely causation due to the patient's 15 minutes of profound untreated low blood pressure.
What makes you a good expert for this case?
I am an author of a hospital safety book just released. See this link:https://www.amazon.com/gp/product/B086K666QY/ref=dbs_a_def_rwt_bibl_vppi_i1 I write a national monthly blog on medical and healthcare issues. I am a nationally recognized expert in medical safety, liability and malpractice.
How often do you encounter cases similar to this one in your practice?
Fortunately, although I have seen many cases like this, not that often now.
Do you believe there might have been medical error?
Specifically in terms of the anesthesiologist's role in this scenario, it is unlikely that the episode of post-induction hypotension contributed to her postoperative paralysis or motor deficits. The reason being is with the neuromonitoring, the surgeon would have performed baseline values after induction. The surgeon could also request MEPs if there was concern about the 15 minutes of hypotension causing a problem. I would presume that any deficits caused by induction would have been blatantly reflected from those baseline readings PRIOR to surgery beginning. If the surgeon then proceeded after baseline readings were fine, then it is more likely that the outcome was a result of the surgical intervention especially if the surgery was performed at the thoracic level. The thoracic surgery is much more likely to compromise all the vasculature of the abdominal aorta which supplies oxygenation to the spinal cord. There is no mention of the neuromonitoring values before, during and after the completion of surgery which would be very valuable. Preoperative hypertension is extremely common. There is literature that supports permissive hypertension in the preoperative period due to patient's anxiety and the decision to proceed with surgery. It is not below the standard of care to induce the patient with the drugs given without an arterial line. It spares the patient a painful invasive procedure while awake by placing an arterial line after induction. The measures to treat the post-induction hypotension appear to be reasonable. The fifteen minutes of hypotension is not an uncommon phenomenon when patients are taking ACE-inhibitors at home. Once again, the baseline neuromonitoring results would help to distinguish whether there was any spinal cord injury after induction and prior to surgery.
Do you believe there might have been causation (i.e. the medical error resulted in an injury)?
The surgeon had access to neuromonitoring during this case. He could ask for SSEPs or MEPs or both. These key values can help to discern at which point any injury may have occurred. In addition, if there was cause to believe spinal cord ischemia occurred during induction, then surgery should not have commenced. I presume since the surgery took place in this case that the neuromonitoring readings did not show any kind of spinal cord ischemia. It is a known complicationof thoracic spine surgery to have an injury such as this, although it is uncommon. The patient presumably was advised of this risk in the surgical consent. The nature of the spinal stenosis and the higher risk thoracic surgery were known risks and do not implicitly equal a medical error, but possibly due to her spine disease.
What makes you a good expert for this case?
I have spent over 3 years providing anesthesia for spine cases just as these. I have been practicing anesthesia for 16 years. I am currently the anesthesia leader for the ambulatory surgery center in my practice which oversee Pre-Admission Testing and evaluates these specific preoperative issues with patient's medical history. I have also served to formulate all the algorithms for a newly opened hospital's Pre-Admission Testing in Nevada.
How often do you encounter cases similar to this one in your practice?
In terms of post-induction hypotension, this is a very common occurrence. Some patients are more difficult to treat than others. In terms of performing anesthesia for spine cases, I have spent 3 years primarily covering these types of cases in private practice with both neurosurgeons and orthopedic surgeons. I worked closely with the neuromonitoring technologists during the case to provide an anesthetic that allowed them to monitor good signals from the spinal cord. My current practice does not include the surgical specialty.
Do you believe there might have been medical error?
Cases, where the spinal cord is being compressed with physical deficits blood pressure, must be maintained within 20% of baseline and augmented pharmacologically when deviations occur. An arterial line is often employed to keep close tabs on blood pressure. Mean arterial pressures in the 50's are associated with poor neurologic outcomes. Peer-reviewed evidence shows that the duration of hypotension is very important. More prompt and aggressive measures should have been taken to raise blood pressure.
Do you believe there might have been causation (i.e. the medical error resulted in an injury)?
As stated above. Duration and magnitude of hypotension are linked to poor neurological outcome.
What makes you a good expert for this case?
I am board certified in Anesthesiology and Critical Care Medicine. I have taught at a major university and have special training and experience in cardiovascular medicine, physiology, and pharmacology. I have performed anesthetics on literal thousands of these operations. I also review medical records for law firms on a regular basis and provide very detailed reports with references on practice standards.
How often do you encounter cases similar to this one in your practice?
As above I encounter these cases regularly.
Do you believe there might have been medical error?
Hypotension with induction is common, especially with turning patient to the prone position. Deliberate hypotension is often used with spinal surgery. Pressure should have been treated earlier maybe- depends on surgical demands, type of surgical table proper positioning, etc. Need to see records. Anyway, more likely a surgical complication as patients tolerate low pressures pretty well in general. Need to know how high her pressure was preop, why she was treated, and with what prior to surgery: BP control.
Do you believe there might have been causation (i.e. the medical error resulted in an injury)?
A line should have been placed for deliberate hypotensive anesthetic. Bp treated earlier prior to incision. Need to see the record.
What makes you a good expert for this case?
34 years of anesthetic experience. Fellowship in Neuroanesthesia which is mostly spines. Extensive experience doing hypotensive surgery for spine and hip surgery in both inpatient and outpatient procedures.
How often do you encounter cases similar to this one in your practice?
I've have extensive experience in cardiac and spinal cases and have done much deliberate hypotension and trauma with hypotensive patients.
Do you believe there might have been medical error?
Bad outcome case. Surgeons and anesthesiologists would point fingers at each other, so details are all important. Surgeons often have bad outcomes from spine surgery even if everything (from a surgery or anesthesiology point of view has been done correctly. A negative surgical re-exploration does not expiate the surgeon, But if the neurological deficit was caused by hypotension, which is certainly possible, a stronger case would be made if a post-operative MRI showed signs of spinal cord ischemia or infarction (literally, a spinal cord stroke). Many other factors need to be considered, and all the details of the pre-anesthesia assessment, medical clearance for surgery, the authorization of the use of an extra dose of anti-hypertensive medication that day, details of anesthetic induction and patient positioning, how the spinal cord monitoring (somatosensory evoked potentials, or SSEP) was set up (determination of baseline and timing of the monitoring). Deviations from standard of care need to be sought. Details of postoperative care need to be considered because postoperative factors may possibly contribute to poor surgical outcomes. The protocol for the surgeon's medical care of the patient (especially post-operative) needs to be reviewed.
Do you believe there might have been causation (i.e. the medical error resulted in an injury)?
Intraoperative hypotension is the key feature of the case which points the finger at the anesthesia management. However, a much stronger case would be made if spinal cord imaging (MRI) is able to demonstrate signs of spinal cord ischemia or infarction, which would have resulted from hypotension and decreased blood flow to the spinal cord over a critical period of time. A more complete summary of the postoperative neurological examination would also be helpful, since some neurological deficits resulting from either surgical misadventure or improper anesthesia management may be indistinguishable. Adherence to standards of care would be important to establish negligence as a causative factor.
What makes you a good expert for this case?
My anesthesiology training involved specialty focus on neuroanesthesia and spinal cord monitoring. (including somatosensory evoked potentials, or SSEP). My pain management training acquainted me with bad outcomes of spine surgery resulting in chronic pain.
How often do you encounter cases similar to this one in your practice?
I have seen an treated patients (in pain management) who have experienced poor outcomes from spinal surgery of various causes.
Do you believe there might have been medical error?
The patient's blood pressure was in the normal range immediately prior to induction of anesthesia, indicating that the patient had responded appropriately to the preoperative anti-hypertensive medication. Hypotension following induction of anesthesia is commonly seen. Though the case as presented states the time period of hypotension was “extended”, 15 minutes is not an extended time. Hypotension for 15 minutes for a patient in supine (or prone) position is unlikely to result in permanent complications.
Do you believe there might have been causation (i.e. the medical error resulted in an injury)?
Of course it is difficult to comment fully without having seen the anesthesia/surgical record. But assuming there was no intraoperative hypotension of significance beyond what is provided in the case description, I would say it is extremely unlikely that the reported 15 minute period of hypotension post-induction is responsible for the patient’s injury. In an operation such as this, there is a significant and well recognized potential for Surgical injury to the spine resulting in neurological injury to the lower extremities (such as occurred in this case). It is extremely unlikely that a 15 minute drop in blood pressure would cause a specific, localized injury exactly of the type likely to be caused by the surgery itself, in the absence of any other evidence of systemic injury caused by the hypotension. The spinal cord is well collateralized and defended against ischemic insult. As there is no reported evidence of other generalized injury - no stroke/CVA/MI, etc - it is not to be expected that a relatively brief period of hypotension would result in a focal injury which is, in fact, in the distribution of an injury likely to be caused by the surgery.
What makes you a good expert for this case?
35 years experience with General Anesthesia in a major academic center. Member of the departmental QA committee.
How often do you encounter cases similar to this one in your practice?
This is an uncommon, but not rare, and very well described complication of spine surgery
Want to open a case or submit response?
Comments are accepted only from Anesthesiology experts.