hypotension. Bijker et al [60] in a literature review found
more than 50 different definitions of intraoperative
hypotension used in the recent anaesthesia literature.
When it comes to controlled hypotension in the
orthognathic literature, again no consensus is found as
to what constitutes controlled hypotension and how
it would differ from intraoperative hypotension. Bijker
et al [61] found that patient and surgical characteristics,
notably age and duration of surgery and duration of
low blood pressure, influence the relationship between
intraoperative hypotension and adverse outcome.
Controlled hypotension is an anesthesiological technique
to lower the mean arterial blood pressure of the patient
in orthognathic surgery on the presumption that a lower
blood pressure correlates with less blood loss and a
better quality of the operation field. In the orthognathic
literature, hypotension has not been related to adverse
effects except for patients with pre-existing hypofunction.
In these cases, cerebral damage or neurological deficit,
stroke, dysrhythmia, cardiac arrest, or even death have
been reported [32].
The absence of a common definition of hypotension, the
different ways of measurement of arterial pressure, the
different attitudes towards the intraoperative duration of
hypotension, the timing to reverse hypotensive anaesthesia
to discover and address undetected arterial hemorrhage
[29], and the different means to achieve hypotension render
comparisons between study groups difficult. An entire
range encompassing aggressive attitudes (MAP 50–55 mm
Hg), cautious attitudes (blood pressure 20%– 30% below
mean preoperative level), and no deliberate hypotension is
reported with orthognathic surgery.
Measurement of mean arterial pressure was mostly done
with the aid of measurements from a radial artery catheter.
[45] calculated mean arterial pressure with the formula:
systolic pressure × 2/5 + diastolic pressure × 3/5. No other
mean arterial pressure measurement formula was found
in the 50 other retained articles. Contemporary monitors
measuring mean arterial pressure use the following
formula: (diastolic pressure × 2) + systolic pressure) / 3.
3.6.1. Advantages of controlled hypotension
Controlled hypotension has advocates and opponents.
Arguments raised in favour of controlled hypotension
are a shorter operation time, a better quality of the
operation field, diminished blood loss, and lower
blood transfusion. Others question the advantages
of controlled hypotension [6]. Choi and Samman [32]
studied that controversy with a systematic review and
concluded in support of hypotensive anaesthesia, with
three studies reporting a significant decrease of blood
loss in patients receiving hypotensive anaesthesia, two
studies reporting a significant decrease in transfusion
rate, and two other studies demonstrating an improved
surgical field and significant reduction in operation time.
Their conclusion was that hypotensive anaesthesia is
most valuable in operations of long duration when
a large amount of blood loss and consequent blood
transfusion are to be expected.
3.6.2. Minimizing perioperative bleeding
Both surgeon and anesthesiologist have means at
their disposal to affect coagulation, blood loss, and the
quality of the surgical field.
Stomatology Edu Journal
- Anesthesiologist:
• normovolemic hemodilution
• application of Cell Saver Systems
• carefully controlled body temperature
• use of tranexamic acid (antifibrinolytic agent) as a
clot stabiliser
• use of aprotinin (serine protease inhibitor)
• use of desmopressin, increasing coagulant activity
• hypotensive anesthetic techniques
• optimised tissue perfusion by administration of
500 mL of hydroxyethyl starch 6%/200/0.5 before
segmentation of the maxilla [55]
• atraumatic nasal intubation with heated nasal tubes
• avoidance of trauma at adenoid fossa during
intubation
• preoperative injection of human recombinant
erythropoietin (not routine in OMFS)
• preoperative exclusion of bleeding disorders
• maintaining hypocapnia
- Surgeon:
• avoiding perioperative vascular injury
• bipolar electrocoagulation; cutting diathermy
• use of an electrocautery unit to make incisions
• skilled surgeons to perform the operation instead
of residents
• surgical vigilance
• administration of local anaesthesia with
vasoconstrictor immediately after intubation
• timely administration of local anaesthesia in Le Fort I
• fluid injection with vasoconstrictor subperiosteally
at nasal floor
• cocainisation of the nasal mucosa prior to maxillary
surgery
• vasoconstriction of intranasal lining with cottonoid
sponges soaked in nasal decongestant
• placement of the patient in a reverse Trendelenburg
position
• incisions that are cleanly made through the periosteum
• packing of open surgical sites with gauze
• local hemostatics like oxidised regenerated
cellulose (Surgicel®, Ethicon Inc, Johnson&Johnson
Company, Somerville, NJ, USA)
• piezosurgical osteotome
• endoscopic assistance for a controlled dissection
of nasal mucosa [62]
• hemostats and hemoclips
• short duration of operation
• instrumentation that allows suction with built-in
light system
• avoiding venous obstruction
BLOODLOSS AND TRANSFUSION NEED IN ORTHOGNATHIC SURGERY:
REVIEW OF LITERATURE
3.7. Excessive blood loss
Reports concerning the need for blood transfusion also
give some insight into the occurrence of excessive blood
loss, either directly by explicit mention or by observation
of the range of blood loss. Kok-Leng Yeow and Por
[19] report 3 excessive bleedings in 102 orthognathic
patients, occurring from the facial artery, maxillary artery,
and pterygoid plexus separately in three patients. When
we observ