3.6 Effect of perioperative strategies that minimise blood loss

3.6.4 Deliberate induced hypotension

The detailed findings of the systematic review for this intervention can be found in Section 3.5.1 of Volume 1b of the technical report.4 The systematic review process identified one Level I study that assessed the effect of deliberate induced hypotension on blood loss and transfusion volume in patients undergoing orthopaedic surgery.163 The systematic review also identified 10 Level II studies (RCTs) of fair to good quality, in patients undergoing a variety of surgical procedures.164–172

The Level I study included 17 RCTs, which covered six different methods of deliberate hypotension: sodium nitroprusside, volatile anaesthetic, prostaglandin E, epidural blockade, reminfentanil and propranolol. In 16 of the 17 RCTs, the measured mean arterial blood pressure ranged from about 50–80 mmHg.

In patients undergoing radical prostatectomy or major joint replacement, deliberate induced hypotension was associated with a significant reduction in operative blood loss. Induced hypotension also significantly reduced the volume of blood transfusion – the incidence of receiving a blood transfusion in the hypotensive groups was 55.8%, compared to 78.7% in the control groups.163

EVIDENCE STATEMENTS for deliberate induced hypotension	Evidence	Consistency	Clinical impact	Generalisability	Applicability
In adult patients undergoing radical prostatectomy, deliberate induced hypotension (MAP 50–60 mmHg) reduces the incidence of allogeneic blood transfusion.
In adult patients undergoing radical prostatectomy or major joint replacement, deliberate induced hypotension (MAP 50–60 mmHg) reduces the volume of allogeneic blood transfusion.
In adult patients undergoing radical prostatectomy, major joint replacement or breast reduction surgery, deliberate induced hypotension (MAP 50–60 mmHg) reduces the volume of blood loss.
In adult patients undergoing surgery in which substantial blood loss is anticipated, the effect of deliberate induced hypotension (MAP 50–60 mmHg) on mortality is uncertain.		NA	X
In adult patients undergoing surgery in which substantial blood loss is anticipated, the effect of deliberate induced hypotension (MAP 50–60 mmHg) on morbidity is uncertain.			X
In adult patients undergoing surgery in which substantial blood loss is anticipated, the effect of deliberate induced hypotension (MAP 50–60 mmHg) on quality of life is unknown.	NA	NA	NA	NA	NA
In adult patients undergoing surgery in which substantial blood loss is anticipated, the effect of deliberate induced hypotension (MAP 50–60 mmHg) on haemoglobin concentration is uncertain.		X	X
In adult patients undergoing surgery in which substantial blood loss is anticipated, the effect of deliberate induced hypotension (MAP 50–60 mmHg) on coagulation status is uncertain.		NA	X
In adult patients undergoing surgery in which substantial blood loss is anticipated, the effect of deliberate induced hypotension (MAP 50–60 mmHg) on length of hospital stay is uncertain.		NA	X

(See Table 2.2)

RECOMMENDATION – deliberate induced hypotension

R13 Grade C	In patients undergoing radical prostatectomy or major joint replacement, if substantial blood loss (blood loss of a volume great enough to induce anaemia that would require therapy) is anticipated, deliberate induced hypotension (MAP 50–60 mmHg) should be considered, balancing the risk of blood loss and the preservation of vital organ perfusion (Grade C).

MAP, mean arterial blood pressure