¶ Interoperative Hypotension for Anesthesia Patients
You're listening to the Anesthesia Patient Safety Podcast , the official podcast of the Anesthesia Patient Safety Foundation . We're bringing you the very best from the APSF newsletter and website , as well as the latest information in perioperative patient safety . Thanks for joining us .
Hello and welcome back to the Anesthesia Patient Safety Podcast . My name is Allie Bechtel and I'm your host . Thank you for joining us for another show .
We hope you tuned in last week when we started the conversation about intraoperative hypotension , usually defined as mean arterial blood pressure less than 65 millimeters of mercury and the threat to anesthesia patient safety . An important part of every anesthetic plan should include minimizing the occurrence , severity and duration of intraoperative hypotension .
Before we dive into the episode today , we'd like to recognize Blink Device Company , a major corporate supporter of APSF . Blink Device Company has generously provided unrestricted support to further our vision that no one shall be harmed by anesthesia care . Thank you , blink Device Company . We wouldn't be able to do all that we do without you .
Our featured article once again today is Interoperative Hypotension a public safety announcement for anesthesia professionals by Amy Yerden , matt Scherer and Desiree Chappell . To follow along with us , head over to APSForg and click on the newsletter heading . The first one down is the current issue . Then scroll down until you get to our featured article today .
I will include a link in the show notes as well . Let's start with a quick review from last week . Here are some of the highlights . Intraoperative hypotension is a big threat to anesthesia patient safety .
It is associated with postoperative complications , including acute kidney injury , myocardial injury after non-cardiac surgery , delirium and stroke , as well as increased morbidity , mortality and hospital readmissions . Interoperative hypotension occurs when the blood pressure drops below a safe threshold , leading to end organ hypoperfusion .
Here are some blood pressure thresholds to keep in mind Map less than 65 for longer periods of time , or any map less than or equal to 55 , since these are associated with an increased risk for adverse postoperative outcomes .
Monitoring blood pressure may be done with intermittent , non-invasive blood pressure cuffs , which may allow hypotensive events to remain undetected for longer duration . Continuous blood pressure monitors are available with an invasive intra-arterial line or a non-invasive finger cuff device .
Benefits for continuous blood pressure monitoring include less blood pressure variability , improved hemodynamic stability , detection of hypotensive events that may be missed by intermittent blood pressure monitoring , earlier recognition and treatment of intraoperative hypotension and an overall reduction in intraoperative hypotension .
And now we are ready to get back into the article , right where we left off . Remember , an important part of every anesthetic plan should be to minimize the occurrence . Important part of every anesthetic plan should be to minimize the occurrence , severity and duration of intraoperative hypotension .
At the same time , we must be careful to avoid inappropriate fluid and vasopressor administration , which may lead to end organ damage as well . This seems like a good time for a literature review . Check out the show notes for the citations . First up we have the article by Ari Yerothny and colleagues .
This is a retrospective cohort study of elective non-cardiac surgery patients over the age of 65 years old who developed acute kidney injury within 48 hours of surgery . Interoperative factors included interoperative hypotension , with mean arterial blood pressure less than 60 or systolic blood pressure less than 90 , and interoperative vasopressor use .
The results revealed that the majority of the hypotensive events were short , lasting less than 10 minutes , while vasopressors were used in the majority of cases , at almost 85% .
The authors concluded that high vasopressor use , greater than 20 milligrams of any specific vasopressor , was associated with postoperative acute kidney injury in this cohort of patients , and this was independent from hypotensive events .
Next up we have the 2020 article by Analik and colleagues that evaluated postoperative hypotension in patients undergoing abdominal free flap breast reconstruction with ERAS protocol and fluid restriction .
Compared to traditional management , the authors observed the following in ERAS patients A higher rate of postoperative symptomatic hypotension , less intraoperative IV fluid administration , increased duration of intraoperative hypotension and no differences in postoperative urine output and adverse events . We are moving on to a bigger multicenter study .
Check out the 2022 study by Chu and colleagues that evaluated over 32,000 abdominal surgery patients over a five-year time period with the multicenter perioperative outcomes group , or MPOG , institutions . Results included the following Increased rates of AKI acute kidney injury even with a reduction in intraoperative hypotension .
Decreased intraoperative fluid administration and increased vasopressor use , which were both associated with increased incidence of acute kidney injury and a greater than 50% decreased risk for the development of AKI , when the crystalloid administration increased from 1 to 10 mL per kg per hour .
The big takeaway from this study is the idea that the administration of vasopressors .
The big takeaway from this study is the idea that the administration of vasopressors to treat or prevent intraoperative hypotension , while minimizing IV fluid administration , may lead to adverse effects , including decreased splanchnic and renal perfusion , leading to ileus , postoperative nausea and vomiting , surgical site infections and AKI , vomiting , surgical site infections and AKI
. Now it's time to review the differential diagnosis for intraoperative hypotension . Here we go Reduced myocardial contractility , vasodilation , hypovolemia , bradycardia , extrinsic compression of heart chambers from a pericardial effusion or pneumothorax or a combination of these . We can turn to some of our more advanced monitoring to help prevent , diagnose and treat hypotension .
These monitors provide information about stroke volume , cardiac output and stroke volume variation volume , cardiac output and stroke volume variation . This allows us to provide goal-directed therapy to treat intraoperative hypotension and work to keep patients safe , rather than just giving vasopressors to treat a blood pressure number .
Do you practice goal-directed therapy while providing anesthesia care ? The authors define goal-directed therapy as the optimal administration , at the most appropriate time , of fluids , inotropes and vasopressors , while being guided by an advanced hemodynamic monitor . The goal is to optimize tissue oxygen delivery and prevent organ hypoperfusion with treatment for a specific endpoint .
Check out figure 1 in the article for a visual representation of goal-directed therapy . The top of the chart is goal-directed therapy . The next row branches into the two strategies of goal-directed hemodynamic therapy and goal-directed fluid therapy .
The row below that includes the interventions of fluids , inotropes and vasopressors for hemodynamic therapy and fluids for fluid therapy . The hemodynamic variables that can be used to help guide fluid therapy include stroke volume and stroke volume variation .
You can use cardiac index to help guide inotrope administration and systemic vascular resistance to guide vasopressor administration . If we look a little closer at goal-directed fluid therapy , we see that the goal is to identify which patients are preload dependent and will respond to a fluid bolus with an optimized position on the Frank-Starling curve .
We can use advanced hemodynamic monitors to assess fluid responsiveness . According to the 2020 Perioperative Quality Initiative Consensus Statement on Intraoperative Fluid Management , assessment of fluid responsiveness is the safest and most effective way to guide fluid therapy .
It is vital to optimize stroke volume with appropriate administration of IV fluids to maintain circulating volume and gut perfusion to help decrease postoperative complications . And gut perfusion to help decrease postoperative complications .
If we look a little closer at goal-directed hemodynamic therapy , the goal is to maintain mean arterial blood pressure and avoid intraoperative hypotension . Goal-directed therapies have been shown to decrease morbidity , mortality and postoperative complications . Decrease morbidity , mortality and postoperative complications .
This is an important step for helping to keep patients safe during anesthesia care . Let's turn our attention to the FEDORA trial . This prospective multi-center randomized control study looked at postoperative complications within the first 180 days after surgery in adult patients undergoing major elective surgery .
Esophageal Doppler monitor-guided goal-directed hemodynamic therapy was used to guide administration of fluids , inotropes and vasopressors with hemodynamic variables of stroke volume , mean arterial blood pressure and cardiac index .
Compared to IV fluid administration with traditional principles , interoperative goals in the goal-directed hemodynamic therapy group included maximal stroke volume , mean arterial blood pressure greater than 70 , and cardiac index greater than or equal to 2.5 . Now for the results . Drum roll please .
450 patients were included and there were less complications and shorter hospital length of stay in the goal-directed hemodynamic therapy group , as well as less acute kidney injury , pulmonary edema , respiratory distress syndrome and wound infections . There was no significant difference in mortality between the groups .
When high-risk patients are managed with goal-directed hemodynamic therapy protocols , there was a decreased risk for postoperative organ dysfunction . Elderly patients undergoing spine surgery can also benefit from goal-directed therapy , with less intraoperative hypotension , postoperative nausea and vomiting and delirium .
According to the 2018 study by Zhang and colleagues , multiple studies have demonstrated that goal-directed therapy can be used to decrease intraoperative hypotensive events and benefit patients undergoing surgery and anesthesia . Care from low-risk patients all the way up to the highest-risk patients . Care from low-risk patients all the way up to the highest-risk patients .
The authors highlight that intraoperative hypotension is a serious public health issue and should be avoided in all age groups and for any length of time . We have tackled the problem by treating hypotension after it has already occurred . This is likely too late , placing patients at risk for end organ damage .
Going forward , we need to harness technology of artificial intelligence and machine learning in order to predict intraoperative hypotensive events and then reduce and prevent them . Have you heard of the Hypotension Prediction Index , or HPI ? The HPI provides a unitless number on a scale from 0 to 100 , which indicates the likelihood that a hypotensive event will take place .
The monitor also provides information about the likely underlying cause of the impending hypotensive events so that the correct intervention may be performed . Studies evaluating HPI have shown that this technology has the potential to decrease the occurrence , duration and severity of intraoperative hypotension during non-cardiac surgery .
For this monitor to work , protocols must be followed to provide appropriate management . This is a good example of how reducing practice variation with protocols can help to decrease intraoperative hypotension . Anesthesia professionals are charged with minimizing intraoperative hypotension . How can we do this ?
Check out figure 2 in the article for a next step guide to help us achieve this . These are all actionable items . It starts with a call to action . Then we must measure rates of postoperative acute kidney injury . Reporting is important and facilities must report outcomes to frontline anesthesia professionals .
We need continued education on intraoperative hypotension , increased and routine use of continuous hemodynamic monitoring when it's available or applicable , use of predictive algorithms for hemodynamic management and , finally , protocolization to reduce practice variation .
The authors leave us with the call to action that intraoperative hypotension is a modifiable risk that we simply should not continue to tolerate . Keep in mind that it is more than just treating the number on the monitor with vasopressors .
Goal-directed therapy is an important part of anesthesia care , to treat the underlying cause of the hypotension and provide adequate end-organ perfusion . We made it to the end of the article , but before we wrap up for today , we are going to hear from Yurden again . I also asked her what she hopes to see going forward .
Let's take a listen to what she had to say .
Our hope is to raise awareness of the importance of appropriate intraoperative hemodynamic management . Going forward , we want to emphasize that it's not just about blood pressure , it's about flow and perfusion to the organs .
There has been much focus on intraoperative hypotension , or IOH , but we need to recognize that hemodynamic instability is the most important issue and strive to correct the cause of the instability . Ioh is just a symptom of the true problem . We need to treat the cause of hemodynamic instability , not just the numbers on the monitor .
I envision intraoperative anesthesia care , transitioning to continuous blood pressure monitoring so we can minimize hemodynamic instability , so that no patient may be harmed by anesthesia care . This would also allow for advanced hemodynamic monitoring and the potential for predicting and therefore preventing hemodynamic instability in IOH .
Thank you to Yurden for contributing to the show today . We are looking forward to improved interoperative blood pressure and advanced hemodynamic monitoring as we work towards , ultimately , the prevention of interoperative hypotension . If you have any questions or comments from today's show , please email us at podcast at apsforg .
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