10 February 2014, Singapore: New trial results1 have shown that the world's first Double Intravenous Vasopressor Automated (DIVA) System affords superior control of maternal blood pressure in women undergoing caesarean section under spinal anaesthesia, when compared with manually-administered medication to manage reduced blood pressure (vasopressor).
Developed by doctors at KK Women's and Children's Hospital (KKH), the novel DIVA System detects and responds rapidly to low blood pressure and/or slow heart rate in real time by auto-administering a precise amount of the recommended vasopressor. The system uses an advanced decision algorithm to help enhance patient safety.
Randomised controlled double-blinded trial:
Putting the DIVA System to the test, the KKH team conducted a randomised controlled double-blinded trial1 involving 213 healthy women between the ages of 21 and 45, with singleton full-term pregnancies. The women underwent elective caesarean delivery under spinal anaesthesia. The system was enhanced with a more responsive vasopressor delivery algorithm, enabling swifter intervention to manage changes in maternal blood pressure.
Compared to the women whose vasopressors were manually administered, women who underwent blood pressure management by the DIVA System experienced:
- Better systolic blood pressure control
- Reduced incidence of nausea
The trial results reinforce findings from a 2011 preliminary study2 jointly carried out by KKH and Duke-NUS Graduate Medical School (Duke-NUS GMS) on 55 women between the ages of 21 and 45, which showed that the DIVA System is clinically more effective in maintaining blood pressure during caesarean sections under spinal anaesthesia than traditional physician-administered techniques using conventional blood pressure monitoring.
DIVA System's enhanced speed and accuracy delivers a safer and better birth experience for patients
The trial was conducted among KKH patients from October 2011 to July 2012. The principal investigators were Professor Alex Sia, Chairman, Medical Board, KKH, and Dr Sng Ban Leong, Consultant, Department of Women's Anaesthesia, KKH. They were assisted by Mr Paul Tan Hon Sen, a third-year medical student at Duke-NUS GMS.
"During the trial, the women who underwent blood pressure management using the DIVA system experienced less hypotension and reduced incidence of nausea, with no increase in the amount of vasopressor required. These are important enhancements to patients' care and experience during caesarean delivery," says Dr Sng.
"With the enhanced algorithm, the system is even more responsive to blood pressure fluctuations. This enables us to keep a tighter control of maternal blood pressure and tailor vasopressor administration to the patient's individual need."
For Prof Sia, who is also Senior Consultant, Department of Women's Anaesthesia, KKH, the results of the clinical trial are an affirmation of the importance of innovation in enhancing patient safety, experience and clinical outcomes.
"We are always on the lookout for innovative ways to better the quality of care we can provide to patients. The DIVA System helps us to monitor our patients more closely and provide medical intervention almost instantaneously. This provides them a more comfortable experience during caesarean delivery, and most importantly, reinforces maternal and fetal safety."
The study was approved by the SingHealth Centralised Institutional Review Board and funded by a National Medical Research Council Exploratory Development Grant. The team has been awarded a SingHealth Foundation Grant to further enhance the system.
Better blood pressure management with the DIVA System
Low blood pressure can occur in up to 60 percent of caesarean sections under spinal anaesthesia, requiring the administration of vasopressors by the attending anaesthetist. Low blood pressure can cause nausea in the mother and, in severe cases, result in reduced blood flow to the baby unless medical intervention is provided.
When a mother undergoes a caesarean section under spinal anaesthesia at KKH, the attending anaesthetist administers spinal anaesthesia and monitors blood pressure throughout the surgical procedure. Where required, the anaesthetist manually administers vasopressors to maintain optimal blood pressure.
Optimal timing and dosing of vasopressors is dependent on accurate and timely blood pressure monitoring. Conventional non-invasive blood pressure monitoring occurs at 60 second intervals - which could result in a potential delay in detecting rapid blood pressure changes within these 60 seconds.
Setting a new standard in speed and accuracy, the DIVA System is an automated dual-pump system which innovatively integrates continuous non-invasive blood pressure monitoring to ensure closed-loop vasopressor administration during the surgery. It continuously measures and records blood pressure and heart rate every second, allowing extremely rapid detection of blood pressure changes and episodes of low blood pressure.
When low blood pressure and/or slow heart rate are detected, the DIVA System automatically, promptly and safely administers the precise amount of the appropriate vasopressor required to restore optimal blood pressure - making the process much more efficient than manual administration.
Caesarean sections are commonly performed under spinal or epidural anaesthesia, and patients remain awake during the procedure.
How the DIVA System works
The DIVA System calculates the amount of vasopressor to administer using a customised algorithm based on integrated blood pressure data from a continuous non-invasive arterial blood pressure (CNAPTM) monitoring system. A closed-loop feedback system controls vasopressor administration, ensuring that the patient receives only the precise dosage required (Figure 1).
The system functions as follows:
- Two alternating finger cuffs measure the patient's arterial blood pressure and heart rate per second.
- The data is exported to a laptop computer, and integrated every ten seconds using a customised programme to determine the dosage of vasopressor required.
- If low blood pressure occurs, phenylephrine is administered automatically via a syringe pump. If low blood pressure occurs in conjunction with slow heart rate, ephedrine is administered instead via a different syringe pump.
- The vasopressor is administered over ten seconds, followed by a ten-second lockout period to permit the vasopressor to take effect.
Benefits of the DIVA System:
- Non-invasive, rapid and automatic detection and response to low blood pressure and slow heart rate
- Delivers individualised optimal vasopressor dosing regimen
- Maintains systolic blood pressure near to baseline blood pressure3
- Alleviates pre-delivery nausea and vomiting