But how long did you keep the patient in this position after the spinal insertion? If it was less than1 5-20 minutes, the bupivacaine will still shift as per my previous post, and a high spinal will result.

Injecting LA into the mid-lumbar area, the needle is at the highest point of the lumbar lordosis whent he patient lies supine. It then sinks down the lumbar and lower thoracic column until it meets the uphill thoracic kyphosis which limits how high the bupivacaine goes - usually mid-thoracic. It takes about 20 minutes to fix to tissues.

If you positioned the patient prone immediately after injecting the anesthetic, the thoracic kyphosis becomes a depression rather than a hill, and the LA would continue to flow into the higher thoracic dermatomes, paralysing the intercostals and blocking all the sympathetics.

All you need here is a saddle block - sacral dermatomes. Inject the heavy bupivacaine, sit the patient up and keep them sitting for 15-20 minutes before positioning them prone.

Quote from: Matthew Parsons on January 25, 2005, 08:00:48 PM
Having said that, I must admit I see little harm in using it on almsot everybody.

A few years ago in my hospital, there was a adult who had a GA for an MRI scan (the GA because she was severely claustrophobic). All went well until the staff re-entered the MRI room at the end and noticed a nasty burning smell. The MRI had induced a current within the ECG dots and had caused burns on all three locations. Required skin grafts to repair. And these were MRI-approved ECG dots!

Don't know about England, but here in Australia it is common practice for anaesthetic staff to not wear face masks in theatre. Certainly not universal but common. Or at most a token attempt to comply with surgeons wishes - the aneasthetist is the one with a face mask on but hanging well below the nose.

In my hospital also, there are two surgeons who do not wear face masks during surgery, although both wear eye protection.

As I understand it, face masks do not provide any patient protection afterthe first 15 minutes of use (by which time they are saturated with surgeons fomites). In fact there is some evidence to show that by continual rubbing against the face, they promote shedding of skin cells onto the patient and therefore are more harm than good. Of course, they will protect the surgeon from inadvertent blood and fluid splashes from the patient.

Our infectious diseases department has decreed that for most surgery, face masks are to be worn by all theatre personel who are within 2 meters of the surgical site -this excludes the anaesthetist for most cases. They have decreed that anaesthetists should wear masks while intubating (for our own protection, rather than the patient's).

I note jetproppilot's comment about medicolegal reasons to wear masks - its interesting to note that the legal profession does not use evidence-based practice to formulate a case, because then there would be no case to be made for face masks.

I also use this a lot. A minor disadvantage is  for orthopedic procedures where the other leg is swung out of the way of the X-Ray, patient may complain of pain/stiffness in that leg with a prolonged operation

Quote from: naveen laiker on January 15, 2005, 09:03:33 AM
Just because u like and use LMA a lot.u cant cross the limit.BE sure to be concerned as soon as ETCO2 enters in 50s.If not satisfied INTUBATE and hyperventilate.GET BLOOD GASES FOR SAFETY OF PATIENT

Yes, but WHY? What harm will it do? IS there any evidence of harm to aptients when CO₂'s get high for short (or long) periods?

And more:

QuoteThe Utility of Cerebral Oximetry in Critically Ill Patients
Susan Marlow, Ken Parsons, Violet Miller and Brian J O'Neil
Saint John Hospital: Detroit, MI

ABSTRACT

Objective:
Jugular bulb oxygen saturation has been correlated to the adequacy of resuscitation and neurologic outcomes in critically ill patients. Regional cerebral oximetry (rSO2) provides a continuous, non-invasive method to monitor cerebral oxygen saturation in the frontal lobes, which is highly correlated with jugular bulb oxygenation. Our aim is to study the utility of rSO2 in the resuscitation of critically ill patients in the emergency department (ED).

Hypothesis:
Cerebral oximetry predicts the adequacy of resuscitation and neurologic outcomes.

Methods:
A prospective observational study was performed on a convenience sample of critically ill patients with altered mental status at a community hospital ED. The INVOS cerebral oximeter was used to detect rSO2. Cerebral oximetry, vital signs, acid—base status, lactates interventions, creatine kinase—BB (CK-BB), and neurologic status at hospital discharge were recorded. Outcome measures were neurologic outcome, defined by the Glasgow Outcome Scale, and adequacy of resuscitation (AOR), defined by base deficit and lactate levels. Data were analyzed utilizing descriptive statistics and Pearson correlation.

Results:
Twelve subjects were enrolled. Five patients either maintained or were quickly resuscitated to rSO2 levels between 50% and 80% and all displayed both adequate resuscitation and returned to normal activity. Five patients had rSO2 outside the above range, 4 below (all with inadequate resuscitation), and 1 above, (large frontal bleed), all 5 of whom died. Two patients had rSO2 within normal ranges; both had intracranial bleeding in the posterior circulation and poor neurologic outcomes. The rSO2 had positive predictive values (PPVs) of 100% and 57% and negative predictive values (NPVs) of 40% and 100% for neurologic outcome and AOR, respectively.

Conclusion:
In critically ill patients, cerebral oximetry has excellent positive and negative predictive values for neurologic outcome and adequacy of resuscitation, respectively. This study is limited by the small sample size.

And this link is also interesting:

Quote
Sudden Severe Hypotension During Induction Of Anesthesia For Carotid Endarterctomy (CEA):
The Utility Of NIRS. A Case Report.

A quick Google search found this:

QuoteObjectives:
The timing of bifrontal decompressive craniectomy (BDC) in patients with intractable intracranial hypertension (IH) is crucial, and the decision to do surgery is based primarily on invasive neuromonitoring. In this report the authors show the efficacy of a non-invasive, near infrared transcranial cerebral oximeter (TCCO) in the management of a patient with post-traumatic IH.

Clinical Presentation:
A 14-year-old male patient who had severe head injury following road traffic accident (RTA). His Glasgow Come Score (GCS) was 6/15. Brain computerized tomography (CT) scan showed multiple brain contusions and diffuse brain edema. He developed a state of IH that did not respond to standard medical treatment. We have used TCCO for neuromonitoring, its readings showed marked difference between the two cerebral hemispheres and this correlated well with the clinical and radiological findings.

Intervention:
Because of the decreasing trend of cerebral oxygen saturation and pupillary changes (anisocoria) BDC was performed. The timing of surgery was appropriate as no brain infarction occurred. Following surgery, TCCO readings were normal and the patient recovery was dramatic and relatively quick.

Conclusion:
TCCO may be an efficient Neuromonitoring tool in determining the time for surgical interference in patients with IH following RTA.

Citation:
Sherif El-Watidy, Abdelazeem El-Dawlatly, Zain A. Jamjoom, Essam El-Gamal: Use of Transcranial Cerebral Oximeter as Indicator for Bifrontal Decompressive Craniectomy. The Internet Journal of Anesthesiology. 2004. Volume 8 Number 2.

But also This:

QuoteCrit Care Med. 1997 Jul;25(7):1252-4.

Failure of the INVOS 3100 cerebral oximeter to detect complete absence of cerebral blood flow.

Gomersall CD, Joynt GM, Gin T, Freebairn RC, Stewart IE.

Department of Anaesthesia and Intensive Care, Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, NT.

The only block I do while the patient is under a GA is the fascia iliaca block that I have described on another post. The reasoning is that because we are deliberately avoiding the femoral nerve and aiming for the fascia iliaca space, we are very unlikely to hit the femoral nerve and cause damage.

There is a reliable genetic test for the porcine model of MH. The human situation is more complex. While many MH-susceptible patients have a specific ryanodine receptor defect that can be identified with genetic testing, there is much heterogeneticity in human MH patients. I.e. there are multiple genetic mutations that can predispose to MH and therefore a single genetic test will not pick up all variants, making any single genetic test unreliable. If a patient is identified with a specific genetic defect, then all relatives would be reliably picked up with a test for that mutation. But screening a patient with a vague history, or even known MH with an unkown genotype variant is not feasable at present.


The halothane caffeine contracture test remains the standard as it tests the final common (clinical) pathway of the disorder.

For a variety of reasons, the anaesthetists in Canberra (and I suspect most of Australia) are moving away from epidural blocks for hip and knee replacement surgery. The main concern is the higher-than-we-thought incidence of major spinal cord complications probably secondary to the use of Clexane post-op in these patients.

We have had a huge shift to GA plus fascia iliac blocks (3-in-one lumbar plexus blocks).

The fascia iliac block is put in either before induction, or during the emergence period.

The technique is to use a sterile epidural kit and threading an epidural catheter into the fascia iliaca compartment. This lies about 4cm lateral to the femoral artery. The 2 "pops" are felt as the fascia lata and then the fascia iliaca. Theoretically the higher you thread the catheter, the more of the lumbar plexus (in particular the lat. cut. n of the thigh) you can block. A weak solution (eg bupivacaine 0.125%) is run in at 10mL/hr with boluses if required)

The advantages are very easy insertion, almost risk-free (well away from the femoral artery and even lateral to the femoral nerve), no hemodynamic consequences of sympathetic blockade, and no narcotic involved. Patients usually require a morphine PCA as well, but their narcotic requirements are markedly reduced.

The disadvantages are variable efficacy (there is no guarantee that your catheter will feed caphalad), and a difficulty in fixation leading to early failure if dislodged.

I am interested in international experiences with epidurals in this patient group and others experience with fascia iliac blocks.

Our hospital pharmacy makes up a sterile solution in a sterile vial of morphine 500mcg in 0.5 mL for intrathecal use. Not only is it guaranteed sterile, preservative-free, it also requires no dilution, minimising dosage errors.

Where I come from (Canberra, Australia) there has been a definite shift away from regional techniques, and epidurals in particular.

Litigation is on the increase in this country, and politicians are very slow in legal reform. Given the small but definite risks of regional techniques (such as the one described above) and the fact that GA's are so safe with an excellent track record, its no wonder.

The screen is separate. When you insert it, it is identical to a Fastrach LMA. You then attatch the screen which has a very nifty magnetic locater - it just locks on and the connection (and image) is ready in an instant.

Its very slick.

The "Ask an Expert" board is for problem solving. If you have a difficult clinical case coming up that you want some expert opinion with, post the scenario on this board.

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Please read our Disclaimer in the News Section - bottom line is that you use the advice provided here at your own risk, and the advice posted here is in no way a substitute for a thourough reading of the relevent literature.

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Even so, this board should help us in those "unique" and sticky situations that the literature may not cover.

cheers
Rob Lang