Central Neuraxial Blocks and Dopamine infusion

[jafo1964]

A significant number of consultants  are using Dopamine infusion to maintain BP during intra-operative period under CNB including High spinals (T2-4) , Thoracic epidurals or CSE techniques
So any patient coming for an laprotomy or trauma surgery both elective and emergent get a Dopamine infusion started followed by the CNB technique of choice.
Ephedrine and fluids do not play a main role in their management protocol
They claim that all you need to do is maintain BP irrespective of the drug used
I wonder what will be the outcomes in light of the uncorrected volume status,tachycardia and other problems that inotropes produce.

IS this technique scientifically acceptable supported by evidence.
Will the outcomes be affected by this technique

[yogenbhatt1]

Right as you are, even I wonder if it is right to use Dopamin as a routine. And so far as fluids are concerned, many Anaesthesiologists now a days believe that since Hypotension is created by Vasodilation, one should use a vaso constrictor and there is no role of fluids.
But our observation is that if good amount is fluids is not given, the urine output is not good, this makes an obstretrician very much concerned.
I feel a combination of Ephedrin along with fluids is best. One can keep Phenylephrin and  Dopamin to use as a second line.

[frontier]

hi,
in my opinion volume correction with fluid & vasopressors like mephenteramine & ephedrine are ist line drugs.phenyleherine & noradrenaline are 2nd line drugs to quickly combat hypotension.with regards.

[mooh2007]

Dopamine?
i think its not scientific approach i think fluid and ephedrin is the best

[kalpesh shah]

Hi, in my views our technique of anaesthesia should minimally alter the physiology(maintain the basic physilogy). so, regularly using dopamine infusion for hypotension is really questionable. If atall required should be second line of treatment not the preffered.

regards.

[anaesami]

nothing very deviant in using dopamine drip. the major alteration produced by spinal is vasodilation and vasoconstrictor is the obvious and ideal choice to minimise the alteration. in fact i used it for a caesarean case suffering from phaechromocytoma with very gratifying results. giving ephedrine is ok but its action is shortlived and so repeated doses may be necessary. giving fluids is an inferior way of treating a vasodilated circulation which is a leaky one. giving colloids makes a little more sense.

[jafo1964]

"giving fluids is an inferior way of treating a vasodilated circulation which is a leaky one. giving colloids makes a little more sense." - anaesami

I wonder why do you think that a otherwise normal system vasodilated by sympathetic blocakde of SAB is leaky.
Physiology is not so fragile. I wonder if there is any reference to support that arguement.


Hypotension in CNB is primarily due to a decrease in preload , due to decreased venous return to the right side of the heart. This occurs due to the relative hypovolumia due to the sympathetic blockade. The venous capacitance vessels in the lower limbs retain a large amount of blood in them. When preload decreases the CO is also decreased. Decreases in CO produce decrease in Diastolic BP and hence possibly decreases in coronary blood flow. Hence theorotically the myocardial O2 supply can be decreased.

Management must include fluids ( crystalloids or colloids) and vasopressors that produce alpha stimulation and hence increase SVR and BP.
Vasopressors of choice would be phenylephrine, mephentramine, ephedrine, metraminol and nor-adrenaline

Now there is a slight difference between vasopresoors and inotropes.
Vasopresssors increase the SVR without increasing myocardial contractility too much and hence are not arrythmogenic and do not increase myocardial oxygen demand very much.

Inotropes like Dopamine actually increase rate and myocardial contractility and hence increase myocardial O2 consumption

So in a CNB scenario where myocardial O2 supply is low , using dopamine increases myocardial O2 demand and hence worsens the imbalance

Also in sympathetic block of CNB, the myocardial contractility in largely unaffected. So why do  we need to increase contractility, we only need a vasoconstrictor like an alpha agonist.

Dopamine can produce alpha stimulation, but in high doses of > 15mcg/ kg/min. Such high doses can produce severe tachycardia. I wonder if you really used Dopamine in such high doses.

Using dopamine in lower doses primarily acts through
DA2 receptors(< 3 mcg/kg/min) where it will produce splanchnic vasodilatation and hence decrease in MAP
or
BETA recetors ( 15mcg/kg/min) where it will produce tachycardia and vasodilatation and hence decrease in MAP

If you so want an inotrope with alpha action I think adrenaline makes a better choice than dopamine

Dopamine is NOT A PANACEA for hypotension of any cause.
You should google the side effects of Dopamine and see the results

with this arguement i rest my case aganst the routine use of adrenaline to manage hypotension produced by extensive CNB blocks

I  think if after a CNB block a patient needs Inotrope to maintain his BP then the choice of CNB in such a patient itself may be questionable.

Regional anaesthesia has no parallels if used on the right patient for the right indication
But i think we are guilty of abusing RA in certain situations

regs

[anaesami]

Circulation is a leaky one in that it allows low mol.wt.substances like iv fluids to escape. within 20 minutes the fluids would leak out of intravascular space. strictly speaking trying to correct spinal hypotension with iv fluids is like trying to fill a leaking bucket. colloids with their greater staying power is a better option anytime. what shall we do in patients who are already retaining fluid like cardiac or renal if they receive a spinal?
there is no pure vasoconstrictor except probably noradrenaline and methergine. all possess inotropic activity to some extent. the difference is only one of degree.what about ephedrine? is it not an inotrope? if only vasoconstrictors are required, how can one justify the use of ephedrine? there is need for inotrope during spinal anaesthesia - block of cardioaccelerator fibres can lead to fall in CO for which only inotropes are suitable. anyway, the proof of pudding is in eating. to me, the pudding tastes very nice.

[jafo1964]

Crystalloids get out of central circulation within 20 mins in normal circulation. that is normal physiology and not leaky circulation. Leaky circulation is when edema occurs inspite of PCWP being normal like as in sepsis.

We are not debating colloids. But if you look at the Cochrane review there is no statistical difference between use of colloids and crystalloids

Simple - dont give huge neuraxial blocks to patients with renal and CVS disorders who will not tolerate the degree of sympathetic block induced by spinal

Sure ephedrine has alpha and beta effect but it is very short lived. Also increasingly phenylephrine is being recommended to tackle hypotension that requires vasoconstriction

High spinals can block cardioacelarator fibres. The name it self suggests that these fibres will decrease the heart rate and hence cardiac output. In such a scenario anticholinergics may play a better role in restoring rate and CO than inotropes

One man's food can be another man's poison
i wonder if your pudding or my pie is backed by adequate scientific evidence

at the end of the day you and me should be united by the science we practice and not  merely  by our personel experiences, preferences, likes and dislikes........................

These are the days of EVIDENCE BASED MEDICINE

regs

[yogenbhatt1]

HI,
Nothing against Dopamine but still one standard protocol is to be followed. Vasodilatation is created and the bucket has become bigger. Either make the bucket smaller by vasoconstrictors or fill it to keep the volume. Vasoconstrictors start from age old Mephenermine ( Still available and of choice to many) but almost never used due to its renal effects. Next in line will be Ephedrin, though weak, but works good enough. Penylephrin is a better drug, to be kept in reserve if ephidrin does not help and then comes Dopamine and Norad.
Let us keep them in that order as per the need. No need to use a battle tank for a small correction.
Same thing applies to Colloid and cryst.
A combination of Vasoconstrictors and fluids is still the best option.
Right you are, Dr. Jafo.
Regards.

[anaesami]

dopamine drip plus basic requirement of fluids is one of the many options available to combat spinal hypotension and fall in CO. just because many are not using it routinely it does not mean the regime has no value. we all tend to think highly of regimes we are accustomed to. sharing of experience is the core value of this forum and i think i have upheld it. regards.

[Pingwin]

We use fluids and Ephedrinum - which is sometimes given with 500 ml of NaCl (first - the bolus, and then a bag). If the hypotension is lasting despite our treatment, we use Dopamine. Once, or twice - we have given additionally Hydrocostrisonum iv.