Transfusion

Canine Haemoabdomen - Part 2

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Part 2 of the two-part mini-series on canine haemoabdomen based loosely around:

Herold LV, Devey J, Kirby R, Rudloff E. Clinical evaluation and management of hemoperitoneum in dogs. J Vet Emerg Crit Care 2008. 18(1):40-53.

“This clinical review combines a search of the veterinary literature with the clinical experience of the authors to provide a resource for the emergency management of hemoperitoneum in dogs.”

See Part 1 HERE.

1. Maintaining Oxygen-Carrying Capacity

Bleeding – peritoneal or otherwise – involves loss of all blood components including red cells with their oxygen-carrying haemoglobin
Majority of blood oxygen content is haemoglobin-bound; much smaller proportion dissolved in plasma (the two components are inter-related)
Oxygen supplementation plus improving effective circulation by volume resuscitation will help to improve tissue oxygen delivery to a variable extent; but replacing oxygen-carrying capacity – i.e. haemoglobin – is the major factor. 
Haemoglobin is replenished either by transfusing red blood cells and/or by using a haemoglobin-based oxygen-carrying solution (HBOC) – Oxyglobin®
Red cell transfusions: packed/stored or fresh, just red cells or whole blood, allogenic or autologous

“Once volume resuscitation has been initiated, and hemoperitoneum diagnosed, transfusion therapy can be considered to optimize oxygen-carrying capacity.”

Decision to transfuse is multifactorial depending on e.g.

  • Manual PCV/haematocrit – individual and trend
  • Signs suggesting anaemia has become clinically significant
  • Whether red cell loss is on-going and how soon likely to stop/be stopped
  • Cause
  • Etc.

Not all dogs with haemoabdomen will meet transfusion criteria but certainly a number will.

In some cases improving oxygen-carrying capacity will be life-saving; in others it will be (very) helpful but not absolutely necessary for survival.

Transfusing patients with active haemorrhage will inevitably result in loss of some of the transfused product into the peritoneal cavity with only transient benefit on systemic oxygen-carrying capacity. Is this the best short-term use of the product?
Does it make more sense in some cases to withhold red cell transfusion until active bleeding has been stopped?

2. Arresting On-going Haemorrhage

DEPENDS ON CAUSE

Vitamin K anticoagulant rodenticide: replenish clotting factors with plasma
Angiostrongylosis: coagulopathy is complex, multifactorial, poorly understood; plasma may help but may not resolve coagulopathy.

MALIGNANT TUMOUR RUPTURE most common; haemangiosarcoma most common – especially splenic rupture

Timing of surgery (after exclusion of detectable lung metastases of course!) in these cases?

Depends on individual patient, practice circumstances, timing of day etc.

Many cases can be stabilised with volume resuscitation +/- red cell transfusion, monitored closely and have diagnostic imaging +/- surgery with less urgency and more stable for general anaesthesia – e.g. next day if patient presents in the evening. But some will not be stabilised, continue to bleed, dump resuscitation fluids into their abdomen…and need surgery with greater urgency.

Alternative approach is to start volume resuscitation, exclude detectable lung metastases, and operate with emergency approach. Until the bleeding lesion is removed on-going haemorrhage will not be stopped and the patient will not be definitively stabilised?

Especially if your ability to give a red cell transfusion is very limited maybe you don’t want to risk the patient continuing to bleed?

And indeed are you set up in a way that makes it easy or practical to monitor the patient closely for an extended period of time before surgery?

Spectrum of cases and multiple considerations. What is your most common approach? Let me know.

3. Autologous Transfusion (Cell Salvage)

Blood transfusion products and options may be (severely) limited. Can we harvest blood lost into peritoneal cavity and give it back to the patient?

Benefits e.g.

  • Readily available source of transfusion
  • Likely to be cheaper to client
  • Avoids compatibility issues of using allogenic red cells
  • Avoids potential risks associated with storage of red cells
“Autotransfusion is an effective method for rapidly providing red blood cells and intravascular volume when imminent death precludes the preparation of allogenic transfusion or when other blood products are not available.”

More people would be in favour than not as long as strict asepsis and rational technique is used and of course even more so if the perception is that the patient would die without it.

Blood aspirated from abdominal cavity can be processed using automated cell salvage machine (e.g. Cell Saver® 5+ Autologous Blood Recovery System) to separate out red cells, or administered without processing/separation. Either way strict asepsis is essential.

“Intra-abdominal blood is collected aseptically by aspirating into a sterile syringe with paracentesis or by suctioning into a sterile container at the time of surgery…Abdominal blood associated with chronic hemorrhage can usually be collected and infused without anticoagulant because the blood is defibrinated when it comes in contact with the peritoneal surface…However, when hemorrhage is acute and rapid there may be insufficient time for defibrination and anti-coagulation of abdominal blood is necessary before autotransfusion (7 mL of citrate–phosphate dextrose adenine should be added to each 50 mL of abdominal blood collected)…The blood should be administered through a blood administration set or in-line blood filter.”

Is Cell Salvage Contraindicated With Suspected Haemangiosarcoma?

Does aspirating and transfusing abdominal haemorrhage containing haemangiosarcoma cells disseminate cancer systemically? No worthwhile veterinary evidence; small amount of human evidence with other cancer types.
Canine haemangiosarcoma is reported to have metastasised in virtually all patients at the time of diagnosis; if cell salvage is deemed life-saving, should it be done regardless?

“Reported contraindications for autologous transfusion of abdominal blood include the presence of septic peritonitis and the presence of ruptured neoplastic abdominal masses due to the potential for systemic disease dissemination. Desmond et al. reviewed the risk of neoplastic dissemination associated with salvage and autotransfusion of intra-abdominal blood during oncologic surgery in humans. No increase in tumor recurrence or decrease in survival rate was reported. The use of leukocyte depletion filters over the standard red blood cell transfusion filters has been recommended to reduce risk of tumor dissemination by autotransfusion in humans. Leukocyte depletion filters are not readily available in most veterinary practices and may be costly to utilize. There are no studies of metastatic risk with autotransfusion in veterinary patients.”

Cite references from 1990's – nothing more recent?

4. Abdominal Counterpressure (Abdominal pressure bandage)

Intention: apply external pressure to increase intra-abdominal pressure and thereby tamponade bleeding. Realistically intra-abdominal pressure is only likely to be increased sufficiently to exceed venous pressure and reduce venous haemorrhage. Therefore excessively tight bandages do not necessarily offer any greater advantage and are likely to be associated with greater complications.

Contraindications:

  • Pelvic or femoral fractures
  • Respiratory distress due to pneumothorax or pleural effusion
  • Diaphragmatic rupture
  • Head trauma

Repeated abdominal free fluid scanning (potentially use of ‘abdominal fluid score’) increasingly used to monitor disease progression, including on-going blood loss – cannot be done with abdominal pressure bandage in place.

May significantly increase discomfort in post-operative patients, those with abdominal trauma etc.

Place abdominal bandage starting caudally approximately at level of pubis and move cranially up to xiphoid stopping before caudal rib margin.
Removed once patient has remained stable for a reasonable period ideally trying to minimise how long the bandage is in place to reduce potential complications.
Abrupt removal can potentially cause life-threatening hypotension due to rapid redistribution of blood or haemorrhage from vessels where tamponade was previously achieved.
Removal should commence at cranial end (i.e. in opposite direction to how bandage was placed); stagger by cutting a small section every 15-30 minutes.
Monitor patient closely throughout for deterioration.

Do abdominal pressure bandages do anything? Do they actually work?

No published good quality clinical evidence on this.
In absence of contraindications, decision at this time is opinion- rather than evidence-based

Authors write:

“it is often enough to reduce or even stop hemorrhage from vascular defects. In addition the application of abdominal counterpressure also may produce a tamponade effect on bleeding abdominal organs and vessels, reduce the size of peritoneal space and reduce hemorrhage volume.”

…but cite human medicine paper from 1979 as evidence – nothing more recent in people? Nothing more recent in dogs and cats??
[Pelligra R, Sandberg EC. Control of intractable abdominal bleeding by external counterpressure. J Am Med Assoc 1979. 241(7):708–713.]

Authors also write:

“In a study of dogs with experimentally produced hemoperitoneum, application of an abdominal bandage to provide counterpressure improved survival.”

…But cite experimental canine paper from 1986 with tiny sample size (5 dogs versus 3 dogs). Is this really reliable evidence of a clinically significant effect?
That’s great, right? Well, if you look at the reference that is cited it is an experimental paper from 1986 using 5 dogs in one group and 3 dogs in the other and a mechanism of haemorrhage that is not what we deal with clinically. So we must ask whether this is even evidence of a level that we should be paying attention to. Maybe.
[McAnulty JF, Smith GK. Circumferential external counterpressure by abdominal wrapping and its effect on simulated intra-abdominal hemorrhage. Vet Surg 1986. 15 (3):270–274.]

“No clinical evaluations of external counterpressure have been reported in veterinary patients…In the experience of the authors, when hemoperitoneum and ongoing hemorrhage prevents patient stabilization, and no contraindications exist, the application of counterpressure may correct hypotension and reduce or eliminate the need for immediate surgical intervention to control hemorrhage in dogs.”

Decision to use abdominal counterpressure depends on e.g.

  • You, your opinion and anecdotal experience
  • Individual patient and particular circumstances

Do you routinely use an abdominal pressure bandage?
If you don’t routinely do this, would you consider it in certain cases?
And if so, in what types of cases?

If you would like a copy of the main review article on which these episodes are loosely based then use the Contact form on the website, Tweet @VetEmCC or message me via the Veterinary ECC Small Talk Facebook page.

Papers that informed this episode:

Herold LV, Devey J, Kirby R, Rudloff E. Clinical evaluation and management of hemoperitoneum in dogs. J Vet Emerg Crit Care 2008. 18(1):40-53.

Desmond MJ, Thomas MJG, Gillon J, et al. Perioperative red cell salvage. Transfusion 1996. 36:644–651.

Edelman MJ, Potter P, Mahaffey KG, et al. The potential for reintroduction of tumor cells during intraoperative blood salvage: reduction of risk with use of RC-400 leukocyte depletion filter. Urology 1996. 47:179–181.

Hirst C, Adamantos S. Autologous blood transfusion following red blood cell salvage for the management of blood loss in 3 dogs with hemoperitoneum. J Vet Emerg Crit Care 2012. 22(3):355-360.

Kellett-Gregory LM, Seth M, Adamantos S, Chan D. Autologous canine red blood cell transfusion using cell salvage devices. J Vet Emerg Crit Care 2013. 23(1):82-86.

Kisielewicz C, Self IA. Canine and feline blood transfusions: controversies and recent advances in administration practices. Vet Anaesth Analg 2014. 41(3):233-242.

McAnulty JF, Smith GK. Circumferential external counterpressure by abdominal wrapping and its effect on simulated intra-abdominal hemorrhage. Vet Surg 1986. 15 (3):270–274.

Pelligra R, Sandberg EC. Control of intractable abdominal bleeding by external counterpressure. J Am Med Assoc 1979. 241(7):708–713.

Valbonesi M, Bruni R, Lercari G, et al. Autopharesis and intraoperative blood salvage in oncologic surgery. Transfus Sci 1999. 21:129–139.

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015 Canine Haemoabdomen - Part 1

Some Things To Know...

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Recent (April 2015) Facebook post (Veterinary ECC Small Talk page, ER Vet Tech Rounds group):

“When You Hear About A 'Collapsed Dog' What Are The Top Three Differentials That Come To Mind?”

Approximately 150 responses
Haemoabdomen in particular due to splenic rupture mentioned by approximately 80% of respondents

Episode loosely based around:

Herold LV, Devey J, Kirby R, Rudloff E. Clinical evaluation and management of hemoperitoneum in dogs. J Vet Emerg Crit Care 2008. 18(1):40-53.

“This clinical review combines a search of the veterinary literature with the clinical experience of the authors to provide a resource for the emergency management of hemoperitoneum in dogs.”

1. Causes:

Traumatic vs. non-traumatic

NON-TRAUMATIC cases of clinically significant canine haemoabdomen most common – especially rupture of intra-abdominal tumours – especially haemangiosarcoma lesions

Other non-traumatic causes:

  • Haematoma rupture
  • Systemic coagulopathy due to e.g. vitamin K antagonist anticoagulant rodenticides, Angiostrongylus vasorum (canine lungworm)
  • Gastric dilation-volvulus (GDV)
  • Liver torsion
  • Splenic torsion
  • Etc.
“Don’t assume that every dog with a non-traumatic haemoabdomen has a tumour and in particular please don’t go chopping open dogs that have a primary systemic coagulopathy!”

Obviously some dogs will have a secondary consumptive coagulopathy that needs to be managed along with the primary problem.

Clinically significant TRAUMATIC haemoabdomen relatively rare?
Focused abdominal ultrasonography (A-FAST) may reveal small clinically insignificant bleeds more commonly?

2. Canine abdominal haemangiosarcoma:

A dog with a non-traumatic haemoabdomen:

  • What is the probability that this individual dog has a bleeding structural mass lesion as the cause?
  • What is the probability that that bleeding lesion is a tumour rather than a haematoma?
  • If it is a tumour, what is the probability that it is haemangiosarcoma?

Sweeping superficial summary of some papers listed below – papers not been critiqued for quality/reliability:
Malignant neoplasia most common cause of non-traumatic haemoabdomen in dogs occurring in approximately 65-85% of cases
Of those approximately 60-75% are haemangiosarcoma lesions

3. History, Clinical Signs and Physical Examination:

Will depend to an extent on:

  • Cause
  • Single/multiple bleeding episodes
  • Severity of current bleeding episode

Not all cases are collapsed

 “At least 40 mL/kg of peritoneal fluid is required to detect a fluid wave, making abdominal distension an insensitive indicator of early or slow forming free abdominal fluid.”

Radiography more sensitive, ultrasonography even more sensitive
40 ml/kg cut-off: is a universal cut-off rational across breeds, standing vs. recumbent, all palpators? Evidence for this figure??

“Four objectives must be met during resuscitation efforts: (1) to re-establish and maintain effective circulating volume, (2) to diagnose hemoperitoneum and identify database abnormalities, (3) to maintain oxygen-carrying capacity, and (4) to arrest ongoing hemorrhage. The actions to achieve these goals are often undertaken simultaneously depending on the severity of clinical signs. When clinical signs indicating decompensatory shock are present, immediate resuscitation will preclude definitive diagnostic evaluation; however, a rapid assessment of the packed cell volume (PCV), total solids (TS), and abdominocentesis results can be evaluated to confirm a diagnosis of hemoperitoneum.”

Make sure to provide analgesia as needed.

4. Re-establish and maintain effective circulating volume:

How best to resuscitate haemorrhagic hypovolaemia?
Overly aggressive crystalloid resuscitation harmful; rapid increases in intravascular hydrostatic pressure may blow off clots and promote further/on-going bleeding
We can’t leave the patient in a shocked state and on the flipside we don’t want to exacerbate the haemorrhage. So what do you do?

Careful conservative titrated resuscitation; end-point is adequate but not necessarily normal systemic perfusion
Stop resuscitation when end-point reached and continue to monitor closely
Assess and resuscitate perfusion using physical examination parameters – supplemented by blood pressure and lactate if available

‘Hypotensive resuscitation’:

Resuscitate systemic blood pressure to a low-normal end-point (e.g. mean arterial blood pressure (MAP) 60 mmHg; Doppler systolic 80-90 mmHg)
But:
Do not use blood pressure in isolation; systemic blood pressure is a proxy for but not the same thing as systemic perfusion
Ensure non-invasive blood pressure measurements are repeatable/reliable/

See podcast episode 009 for discussion of resuscitation fluids and crystalloids versus colloids

Haemoglobin-based oxygen-carrying solutions provide both oxygen-carrying capacity and colloidal support:

  • Oxyglobin® only one currently available; not in all countries
  • Potentially very expensive resuscitation strategy

‘Haemostatic resuscitation’:

Not mentioned in review article
Replace lost whole blood with comparable blood products – packed red blood cells, plasma, platelets
Increasingly adopted and researched in human medicine; also use of specific clotting factors/clotting factor combinations and antifibrinolytics especially tranexamic acid.
Minimises harm from not replacing like-for-like, also dilutional coagulopathy etc.

Very unrealistic in vast majority of veterinary practice environments? Adequate and timely access to blood components? Financially affordable strategy for pet carers?

5. Diagnosing haemoabdomen:

Venous manual packed cell volume (PCV) and plasma total solids (TS):

May suggest acute haemorrhage – does not localise to abdominal cavity

Both red blood cells and protein are lost from the circulation in haemorrhage and therefore PCV and TS do not change initially:

  • Remember that PCV is a percentage and TS a concentration, i.e. neither is a measure of absolute quantity.
  • In the first few minutes following haemorrhage, the absolute number of red blood cells and plasma protein molecules will be reduced but PCV and TS are unchanged.
  • Fluid then moves from the interstitial compartment into the bloodstream diluting the remaining red cells and protein and causing a decrease in the measured PCV and TS.
    • It takes a while for fluid shift and therefore dilution to occur although it is not possible to be too precise about the exact length of time in clinical patients.
    • In dogs the spleen contracts in response to haemorrhage and expels a large amount of stored red blood cells into the circulation; therefore PCV may remain in the normal range for a while despite low TS, i.e. with blood loss, TS is usually expected to fall first followed by PCV in dogs.
    • The response of the spleen in cats is either much less substantial or in fact non-existent depending on which reference one consults.
  • As yet more time passes PCV will also fall depending on whether haemorrhage is on-going, the severity of any on-going haemorrhage, and any treatment instituted.

Evaluate for systemic coagulopathy

 “Resuscitation efforts should not be delayed while awaiting laboratory results.”

…and I couldn’t agree with that more.

Identify free peritoneal fluid – ultrasonography best way to do this
Aspirate – including potentially with ultrasound guidance – and analyse
Blood lost into the abdomen (and other cavities) often has an echogenic appearance

When analysed the fluid will:

  • Be grossly sanguineous but non-clotting
  • Have a PCV that is similar to (could be lower, same or higher than) the patient’s circulating PCV
  • Have red blood cells, possible occasional erythrophagocytosis, and typically no platelets on cytology
    • Note: although cytology is not required to diagnosis haemoabdomen, it should always be performed to exclude the presence of a concurrent septic process which would then make surgery an emergency following stabilisation.

Beware of over-interpreting fluid aspirated from any body cavity as being consistent with haemorrhage purely based on gross appearance. It is not unusual for fluid to grossly appear consistent with bleeding only for PCV measurement to then be inconsistent – grossly sanguineous fluid can for example have a PCV of less than 5-10%.

“Repeated paracentesis during stabilization and hospitalization provides information to monitor the progression of intra-abdominal bleeding. An increasing trend in the abdominal PCV that parallels a decreasing trend in the peripheral PCV indicates ongoing or active hemorrhage.”

Note that intravenous resuscitation with red cell-free fluids – including plasma – may affect both venous and effusion PCV and hence laboratory evaluation.

Part 2 includes maintaining oxygen-carrying capacity, arresting haemorrhage, possible use of abdominal counterpressure etc.

Papers that informed this episode:

Aronsohn MG, Dubiel B, Roberts B, Powers BE. Prognosis for acute nontraumatic hemoperitoneum in the dog: a retrospective analysis of 60 cases (2003-2006). J Am Anim Hosp Assoc 2009. 45(2):72-77.

Hammond TN, Pesillo-Crosby SA. Prevalence of hemangiosarcoma in anemic dogs with a splenic mass and hemoperitoneum requiring a transfusion: 71 cases (2003-2005). J Am Vet Med Assoc 2008. 232(4):553-8.

Herold LV, Devey J, Kirby R, Rudloff E. Clinical evaluation and management of hemoperitoneum in dogs. J Vet Emerg Crit Care 2008. 18(1):40-53.

Lux CN, Culp WTN, Mayhew PD, et al. Perioperative outcome in dogs with hemoperitoneum: 83 cases (2005–2010). J Am Vet Med Assoc 2013. 242(10):1385-1391.

Pintar J, Breitschwerdt EB, Hardie EM, Spaulding KA. Acute nontraumatic hemoabdomen in the dog: a retrospective analysis of 39 cases (1987-2001). J Am Anim Hosp Assoc 2003. 39(6):518-522. 

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012 Listeners Questions Episode on Blood Administration

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“What are your thoughts about using IVF pumps to administer blood products? The hospital I work at currently will not use fluid pumps, but instead calculates drops/second because they feel the pumps will cause cell lysis.” (Nicky Rivera)

Infusion devices – fluid pumps, syringe drivers – offer certain benefits. They allow fluid or drug therapy to be given reliably in a controlled fashion at a rate of our choosing.
Some inherent inaccuracies with these devices (shhhh!) and differences between devices.

Alternative is gravity flow based on drops per second or seconds per drop but patient movement can have potentially significant consequences on the rate of fluid administration.
May be possible to immobilise limb (typically) to prevent or minimise this – not very patient friendly!

At least one in-line device available in USA which attaches onto the chamber of the fluid administration set and monitors the fluid drops. Alarms if drop rate changes. Does not control fluid rate but aims to improve reliability of gravity flow administration.

Modern volumetric peristaltic infusion pumps typically classified as ‘compatible with’ or ‘suitable for’ blood administration. Most (clearly not all) blood transfusion recipients can move around and transfusions typically given over a period of hours….not using an infusion device could result in a relatively uncontrolled and unpredictable transfusion.

Are there any clinically significant downsides to using an infusion device for blood transfusion? Does what you are thinking about or worrying about actually have any consequences on the patient?

Red cell transfusions (packed red blood cells, sometimes whole blood) typically given to increase recipient oxygen-carrying capacity. Despite what the manufacturers say, could using an infusion device:

  • Reduce the positive benefit the transfusion has on the recipient’s oxygen carrying-capacity?
  • Cause some of the red cells to be broken down during passage through the pump or in some other way cause mechanical damage that affects the ability of the haemoglobin to carry and give up oxygen?
  • Adversely affect the viability of the red cells?
  • In any way increase the likelihood of there being a transfusion reaction?

(I believe that) infusion pumps are approved for clinical use with blood transfusions if manufacturers show that they do not cause in vitro haemolysis.
Infusion device typically not used in human medicine. Can usually ask patient to keep still. Also blood often used as rapid infusion in resuscitation.

In general assumption is that blood administration set with built-in filter used with volumetric infusion pumps; in-line filter added when syringe driver used.

McDevitt RI, Ruaux CG, Baltzer WI. Influence of transfusion technique on survival of autologous red blood cells in the dog. J Vet Emerg Crit Care 2011. 21(3) 2011, pp 209–216.

(Contact me for a copy of the paper)

“A number of studies are available in the human literature that compare peristaltic pumps to centrifugal pumps or other methods of administration…Most of these studies assess damage to red cells in vitro, and rarely examine the effect that transfusion administration has on in vivo red cell survival. Little consensus exists regarding whether or not damage occurs when a particular method is used, and whether or not this is clinically relevant.

Several published studies failed to demonstrate differences in hemoglobin concentration or osmotic fragility when comparing rotary and centrifugal pumps…By contrast, linear peristaltic pumps have been found to increase the free hemoglobin concentration in other studies….[One study] reported an increase in the quantity of RBC fragments when a roller pump is used in comparison with a centrifugal pump. As many of these studies only assessed in vitro parameters, or only involved humans undergoing cardiopulmonary bypass, the clinical significance in dogs is unknown.

The primary objective of the present study was to determine if the method of transfusion has an effect on the lifespan of autologous canine erythrocytes. Additional in vitro studies were also carried out to assess the impact of transfusion technique on canine RBC osmotic fragility, RBC count and hemoglobin concentrations in plasma.”

Study sample size: 9 medium-to-large breed healthy dogs

Collected blood from the dogs, biotinylated* the red cells and then transfused the blood back to the dogs.
(*Labelling red cells by attaching biotin; subsequently allows cells to be monitored.)

“Each dog was autologously transfused in sequence, using 3 different transfusion techniques via a single 20-Ga cephalic catheter:

  • The first preparation of biotinylated RBCs was transfused using a volumetric peristaltic infusion pump and standard transfusion line with built-in 170–260mm filter.
  • The second preparation was transfused using a syringe infusion pump with cells delivered through an 18mm aggregate filter
  • And the final preparation was transfused last via gravity flow using a transfusion line with built-in 170–260mm filter.

Both the infusion pump and syringe pumps were used according to the manufacturer’s specifications.
Transfusion rates for each method were set at 2mL/kg/h, which is the highest transfusion delivery rate used under the standard operating procedure for transfusions used at this institution.
Delivery rate of the control preparation was adjusted by regulating drops/min manually.”

Transfused cells left to equilibrate overnight. Blood samples collected from the dogs morning following transfusion (day 1), and every 7 days until day 49.
These samples were analysed and some other in vitro experimentation also done.

Considerable technical complications during transfusion and sampling.

Authors’ reported results were basically that:

  • There was a significance difference in 24-hour red cell survival between the three transfusion techniques; gravity flow had the highest survival, then volumetric infusion pump, and then syringe pump.
  • After 24 hours, there was no significant difference in the circulating half-life of red cells so regardless of whether gravity flow or a pump was used the red cells that survived the first 24 hours showed no subsequent change in survival time.

“The data presented here suggest that the method of transfusion used to deliver autologous RBCs has a substantial effect on probability of short-term survival of the transfused cells. Particularly remarkable is the apparent [deleterious] effect of delivery via syringe pump and microaggregate filter.
Our initial hypothesis was that the method of transfusion would have an effect on the lifespan of transfused autologous canine erythrocytes; however, we rejected this hypothesis on observation that the transfused cells, having survived the initial equilibration period, showed no significant difference in circulating half-life over the following sampling period.”

Unable to shed light on the mechanisms for what they call “the dramatic losses of autologous RBCs following both pump and syringe administration methods”.

“The present study utilized a comparatively small number of healthy animals, thus the power of this study to detect significant differences in half-life may be reduced. The present study, however, did identify a substantially altered probability of transfusion survival in the immediate post-transfusion period. Of the 3 methods assessed in this study, the greatest effect was noted when red cells were transfused using a syringe pump and microaggregate filter. This method of blood administration is more commonly used in smaller patients (eg, cats, very small dogs), and replication of this finding in cats is warranted.”

Study limitations for clinical application:

  • Small sample size (as mentioned by authors too)
  • Healthy dogs – would findings be replicated in sick dogs being transfused?
  • Autologous* transfusions but typically clinical patients receive heterologous blood – could this difference ne significant? (*Dogs transfused with their own red blood cells)
  • Blood only stored for short period prior to transfusion. Units used clinically often stored for days or weeks with more time for storage lesions to develop – would that compromise red cell viability even more than in this study?

Study was not designed to evaluate clinical significance and patient-centred consequences

In essence what we need to decide is does this study using the methodologies and sample size involved mean that if we use a syringe driver or a volumetric infusion pump in sick dogs there will be a reduction in 24-hour survival and that this reduction will have clinical relevance. And strictly speaking we can’t answer that question.

Heikes BW, Ruaux CG. Effect of syringe and aggregate filter administration on survival of transfused autologous fresh feline red blood cells. J Vet Emerg Crit Care 2014. 24(2):162–167.

Feline red cells meant to be smaller than canine red cells; also some other physical and chemical differences
Transfusion rates typically lower for cats than most clinical canine patients.

“The objective of the study reported here was to carry out transfusion studies of autologous feline RBCs, using essentially the same biotin-labeling and flow cytometry method previously used in the dog, to assess the effect of transfusion technique on short-term survival and circulating half-life of autologous RBCs in the cat. Our hypothesis was that use of a microaggregate filter would be associated with increased risk of early loss and decreased circulating half-life of transfused autologous RBCs in cats.”

6 healthy cats

“The day following blood collection and labeling all cats were transfused with their own, labeled RBCs. Intravenous catheters (22 Ga)j were placed in a cephalic vein, then each cat was transfused in random order using either a syringe pump + microaggregate filter or via a standard blood-giving set (10 drops/mL) using gravity. Blood was transfused at 2 mL/kg/h via syringe pump setting, while administration rates were regulated via drop counting and adjustment for the gravity-administered cells. Gravity administration rates achieved were variable, with most cats receiving the gravity-administered cells over a period of approximately 60 minutes (an overall rate of approximately 4 mL/kg/h for the typical 4.5 kg cat in this study).”

“The data presented here suggest that, in marked contrast to previously reported findings in dogs, the use of a syringe + microaggregate filter system to administer autologous RBC transfusions to cats is not associated with an increased risk of either short-term (<12 h) or long-term (up to 6 wk) accelerated loss of transfused cells. There was no difference in survival attributable to transfusion method in this study….

The study reported here used autologous RBCs with short storage times, a situation that is quite different to one where the patient receives cells from a donor cat that may have been stored prior to administration. The potential impact of mechanical administration systems on survival of stored, allogenic feline RBCs following transfusion is unknown at this time, but is an area of significant interest.

Given the lack of difference in red cell survival and half-life with differing administration techniques in this study, the common practice of using these filters inline does not appear to be contraindicated in feline patients.”

Any evidence from human medicine?

Influence of transfusion technique on transfused cell survival has been investigated in human medicine by various groups using several different methods for transfusion…
BUT typically in vitro studies looking at immediate changes in RBC parameters (e.g. osmotic fragility) rather than in vivo red cell survival.

A reasonable clinical approach to red cell transfusion at this time?

Aim: to give the volume of blood we have calculated over the required period of time.

Too fast may result in unnecessary complications
Too slow may result in delayed clinical improvement, and potentially wastage of product if transfusion time exceeds hospital’s policy necessitating product being discarded.

“I don’t think we have great evidence that the use of infusion devices results in shortened red cell lifespan or reduced viability but there is potentially a signal to be concerned. Given the implications that this might have on the patient’s clinical progression and outcome I guess it makes sense to try not to use an infusion device where possible. In a patient in whom gravity flow alone can be used predictably and reliably, perhaps with the aid of some sort of in-line flow monitoring device, then sure, why not do this.

BUT I would also say that in my personal clinical experience this group would be a minority of the patients I have transfused. Of course that may just reflect my individual case experience but I suspect not. The majority of the patients that I have transfused have had some degree of mobility and activity in their kennel, even if recumbent they can move their limbs or their head. And in these cases I would personally still be using an infusion device based on the evidence that I have found to date

 And I say this partly because one of the things that we do need to factor in is just the plain reality of life in what can often be a busy practice setting. Even if you were using one of those in-line flow monitoring devices, you would still have to have someone available to respond urgently if the alarm sounds. Don’t get me wrong I think if you don’t have any infusion devices and these in-line flow monitoring gadgets work then sure use it but it is still likely to be more labour intensive than when using an infusion device.

If you were using gravity flow of blood to a patient that was able to move around, potentially over a period of 4-6 hours, I would just be worried about being able to monitor that transfusion frequently enough.  Having worked in years gone by in situations where there were either no infusion devices, or not enough infusion devices, I think it can be a real challenge if you are busy and potentially understaffed.

Do you have a different take on the evidence currently available?
Does your practice give all red cell transfusions by gravity flow alone?
If they do, how do you find it? Do you think I am over-egging the practical implications of doing this?

As always, I would love to hear from you!

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008 Clinical Policies and Predictive Transfusion Formulae

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The papers discussed in this episode are:

Accuracy of formulas used to predict post-transfusion packed cell volume rise in anemic dogs by Short, Diehl, Sheshadri and Serrano, published in the Journal of Veterinary Emergency and Critical Care in August 2012. (Volume 22, Issue 4, pages 428–434, August 2012).

Assessment of five formulae to predict post-transfusion packed cell volume in cats by Reed, Espadas, Lalor et al. This is from the Journal of Feline Medicine and Surgery August 2014. (Volume 16, Issue 8, pages 651-656, August 2014).

To find out which formulae were assessed in these papers, click below for your free copy of the transcript: