Closed-Loop Feedback Computer-Controlled Phenylephrine for Maintenance of Blood Pressure During Spinal Anesthesia for Cesarean Delivery: A Randomized Trial Comparing Automated Boluses Versus Infusion

Computer-controlled closed-loop norepinephrine infusion system for automated control of mean arterial pressure in dogs under isoflurane-induced hypotension: a feasibility study

Introduction

Intra-operative hypotension is a common complication of surgery under general anesthesia in dogs and humans. Computer-controlled closed-loop infusion systems of norepinephrine (NE) have been developed and clinically applied for automated optimization of arterial pressure (AP) and prevention of intra-operative hypotension in humans. This study aimed to develop a simple computer-controlled closed-loop infusion system of NE for the automated control of the mean arterial pressure (MAP) in dogs with isoflurane-induced hypotension and to validate the control of MAP by the developed system.

Methods

NE was administered via the cephalic vein, whereas MAP was measured invasively by placing a catheter in the dorsal pedal artery. The proportional-integral-derivative (PID) controller in the negative feedback loop of the developed system titrated the infusion rate of NE to maintain the MAP at the target value of 60 mmHg. The titration was updated every 2 s. The performance of the developed system was evaluated in six laboratory Beagle dogs under general anesthesia with isoflurane.

Results

In the six dogs, when the concentration [median (interquartile range)] of inhaled isoflurane was increased from 1.5 (1.5-1.5)% to 4 (4-4)% without activating the system, the MAP was lowered from 95 (91-99) to 41 (37-42) mmHg. In contrast, when the concentration was increased from 1.5 (1.0-1.5)% to 4 (4-4.8)% for a 30-min period and the system was simultaneously activated, the MAP was temporarily lowered from 92 (89-95) to 47 (43-49) mmHg but recovered to 58 (57-58) mmHg owing to the system-controlled infusion of NE. If the acceptable target range for MAP was defined as target MAP ±5 mmHg (55 ≤ MAP ≤65 mmHg), the percentage of time wherein the MAP was maintained within the acceptable range was 96 (89-100)% in the six dogs during the second half of the 30-min period (from 15 to 30 min after system activation). The median performance error, median absolute performance error, wobble, and divergence were - 2.9 (-4.7 to 1.9)%, 2.9 (2.0-4.7)%, 1.3 (0.8-1.8)%, and - 0.24 (-0.34 to -0.11)%·min-1, respectively. No adverse events were observed during the study period, and all dogs were extubated uneventfully.

Conclusion

This system was able to titrate the NE infusion rates in an accurate and stable manner to maintain the MAP within the predetermined target range in dogs with isoflurane-induced hypotension. This system can be a potential tool in daily clinical practice for the care of companion dogs.

Closed-loop anesthesia: foundations and applications in contemporary perioperative medicine

A closed-loop automatically controls a variable using the principle of feedback. Automation within anesthesia typically aims to improve the stability of a controlled variable and reduce workload associated with simple repetitive tasks. This approach attempts to limit errors due to distractions or fatigue while simultaneously increasing compliance to evidence based perioperative protocols. The ultimate goal is to use these advantages over manual care to improve patient outcome. For more than twenty years, clinical studies in anesthesia have demonstrated the superiority of closed-loop systems compared to manual control for stabilizing a single variable, reducing practitioner workload, and safely administering therapies. This research has focused on various closed-loops that coupled inputs and outputs such as the processed electroencephalogram with propofol, blood pressure with vasopressors, and dynamic predictors of fluid responsiveness with fluid therapy. Recently, multiple simultaneous independent closed-loop systems have been tested in practice and one study has demonstrated a clinical benefit on postoperative cognitive dysfunction. Despite their advantages, these tools still require that a well-trained practitioner maintains situation awareness, understands how closed-loop systems react to each variable, and is ready to retake control if the closed-loop systems fail. In the future, multiple input multiple output closed-loop systems will control anesthetic, fluid and vasopressor titration and may perhaps integrate other key systems, such as the anesthesia machine. Human supervision will nonetheless always be indispensable as situation awareness, communication, and prediction of events remain irreplaceable human factors.

Perioperative Fluid and Vasopressor Therapy in 2050: From Experimental Medicine to Personalization Through Automation

Intravenous (IV) fluids and vasopressor agents are key components of hemodynamic management. Since their introduction, their use in the perioperative setting has continued to evolve, and we are now on the brink of automated administration. IV fluid therapy was first described in Scotland during the 1832 cholera epidemic, when pioneers in medicine saved critically ill patients dying from hypovolemic shock. However, widespread use of IV fluids only began in the 20th century. Epinephrine was discovered and purified in the United States at the end of the 19th century, but its short half-life limited its implementation into patient care. Advances in venous access, including the introduction of the central venous catheter, and the ability to administer continuous infusions of fluids and vasopressors rather than just boluses, facilitated the use of fluids and adrenergic agents. With the advent of advanced hemodynamic monitoring, most notably the pulmonary artery catheter, the role of fluids and vasopressors in the maintenance of tissue oxygenation through adequate cardiac output and perfusion pressure became more clearly established, and hemodynamic goals could be established to better titrate fluid and vasopressor therapy. Less invasive hemodynamic monitoring techniques, using echography, pulse contour analysis, and heart-lung interactions, have facilitated hemodynamic monitoring at the bedside. Most recently, advances have been made in closed-loop fluid and vasopressor therapy, which apply computer assistance to interpret hemodynamic variables and therapy. Development and increased use of artificial intelligence will likely represent a major step toward fully automated hemodynamic management in the perioperative environment in the near future. In this narrative review, we discuss the key events in experimental medicine that have led to the current status of fluid and vasopressor therapies and describe the potential benefits that future automation has to offer.

A Comprehensive Analysis and Review of Artificial Intelligence in Anaesthesia

In the field of anaesthesia, artificial intelligence (AI) has become a game-changing technology. Applications of AI include keeping records, monitoring patients, calculating and administering drugs, and carrying out mechanical procedures. This article explores the current uses, challenges, and prospective applications of AI in anaesthesia practices. This review discusses AI-supported systems like anaesthesia information management systems (AIMS), mechanical robots for carrying out procedures, and pharmacological models for drug delivery. AIMS has helped in automated record-keeping, predicting bad events, and monitoring the vital signs of the patient. Their application has a vital role in improving the efficacy of anaesthesia management and patient safety. The application of AI in anaesthesia comes with its own unique difficulties. Noteworthy obstacles include issues with data quantity and quality, technical limitations, and moral and legal dilemmas. The key to overcoming these barriers is to set guidelines for the ethical use of AI in healthcare, improve the reliability and comprehension of AI systems, and certify the health data precision and security. AI has very bright potential. Exciting future directions include developments in AI and machine learning thus development of new applications, and the possible enhancement in training and education. Potential research areas include the application of AI to chronic disease management, pain management, and the reinforcement of anaesthesiologists' education. AI could be used to design authentic lifelike training simulations and individualized student feedback systems, hence transforming anaesthesia education and training methodology. For this review, we conducted a PubMed, Google Scholar, and Cochrane Database search in 2022-2023 and retrieved articles on AI and its uses in anaesthesia. Recommendations for future research and development include strengthening the safety and reliability of health data, building a better understanding of AI systems, and looking into new areas of use. The power of AI can be used to innovate anaesthesia practices by concentrating on these areas.

Closed-Loop Pharmacologic Control of Blood Pressure: A Review of Existing Systems

Blood pressure management is a critical aspect of patient care, particularly in surgical and critical care settings. Closed-loop systems, which utilize real-time data and feedback to adjust treatment interventions, have gained attention for their potential to enhance blood pressure control. This review explores the application of closed-loop systems in blood pressure management. We discuss various closed-loop approaches, including their mechanisms, benefits, and limitations. By harnessing real-time patient data and feedback, closed-loop systems can tailor interventions dynamically, thus enhancing blood pressure regulation. Additionally, we examine the integration of advanced monitoring technologies and artificial intelligence algorithms in closed-loop systems. The review highlights recent studies and their findings, emphasizing the evolving landscape of closed-loop blood pressure management across different clinical scenarios. From the perioperative period to critical care settings, closed-loop systems hold the potential to optimize patient outcomes by precisely adjusting vasopressor administration in response to continuous blood pressure fluctuations. By providing insights into the current state of closed-loop systems for blood pressure control, this review offers a comprehensive overview of their potential contributions to improved patient outcomes and future directions for research and implementation.

Evaluating an advanced double intravenous vasopressor automated system to treat hypotension during spinal anesthesia for cesarean delivery: a randomized controlled trial

BACKGROUND

The optimal treatment of hypotension during spinal anaesthesia is uncertain. A novel double intravenous vasopressor automated (DIVA) system reduces hypotension compared to standard care, and was subsequently modified to an advanced-DIVA (ADIVA) system. The primary objective was to compare ADIVA versus DIVA on incidence of hypotension (systolic BP (SBP) < 80% baseline).

METHODS

We conducted a randomized-controlled trial in women undergoing elective cesarean delivery under spinal anesthesia. SBP and heart rate were measured continuously using a Nexfin monitor. ADIVA delivered 25 μg phenylephrine (heart rate > 60 beats.min^-1) or 2 mg ephedrine (heart rate < 60 beats.min^-1) at SBP 90 to 110% of baseline, 50 μg phenylephrine or 4 mg ephedrine at SBP 80 to 90%, and 75 μg phenylephrine or 6 mg ephedrine at SBP < 80%. ADIVA calculated the trend of SBP; vasopressors were administered rapidly if SBP trended downward, or 30 s if SBP trended upward. In contrast, DIVA delivered 25 μg phenylephrine or 2 mg ephedrine at SBP 90 to 100% of baseline, and 50 μg phenylephrine or 4 mg ephedrine at SBP < 90%. Boluses were followed by a 10-s lockout. Other outcomes included hypertension (SBP > 120% baseline), vasopressor consumption, clinical outcomes, and performance measures from spinal anesthesia to fetal delivery.

RESULTS

We analyzed 94 parturients (ADIVA: n = 46, DIVA: n = 48), with no difference in the incidence of hypotension between ADIVA (78.3%) and DIVA (83.3%, p = 0.677). ADIVA had significantly higher proportion of hypotensive SBP readings, lower phenylephrine consumption and higher umbilical arterial pH. There was no difference in hypertension, bradycardia, ephedrine consumption, intravenous fluid volume, nausea/vomiting, Apgar scores, and umbilical venous pH or lactate. ADIVA maintained SBP higher above baseline with greater fluctuation than DIVA.

CONCLUSION

ADIVA was associated with a greater proportion of hypotensive SBP readings, reduced phenylephrine consumption, and increased umbilical arterial pH than DIVA. Further research is needed to determine the optimal method of vasopressor delivery in parturients undergoing cesarean delivery.

TRIAL REGISTRATION

This study was registered on Clinicaltrials.gov registry (NCT03620942) on 08/08/2018.

Systolic Arterial Pressure Control Using an Automated Closed-Loop System for Vasopressor Infusion during Intermediate-to-High-Risk Surgery: A Feasibility Study

Introduction: Vasopressor infusions are essential in treating and preventing intraoperative hypotension. Closed-loop vasopressor therapy outperforms clinicians when the target is set at a mean arterial pressure (MAP) baseline, but little is known on the performance metrics of closed-loop vasopressor infusions when systolic arterial pressure (SAP) is the controlled variable. Methods: Patients undergoing intermediate- to high-risk abdominal surgery were included in this prospective cohort feasibility study. All patients received norepinephrine infusion through a computer controlled closed-loop system that targeted SAP at 130 mmHg. The primary objective was to determine the percent of case time in hypotension or under target defined as SAP below 10% of the target (SAP < 117 mmHg). Secondary objectives were the percent of case time “above target” (SAP > 10% of the target or >143 mmHg) and “in target” (within 10% of the SAP target or SAP between 117 and 143 mmHg). Results: A total of 12 patients were included. The closed-loop system infused norepinephrine for a median of 94.6% (25−75th percentile: 90.0−98.0%) of case time. The percentage of case time in hypotension or under target was only 1.8% (0.9−3.6%). The percentages of case time “above target” and “in target” were 4.7% (3.2−7.5%) and 92.4% (90.1−96.3%), respectively. Conclusions: This closed-loop vasopressor system minimizes intraoperative hypotension and maintains SAP within 10% of the target range for >90% of the case time in patients undergoing intermediate- to high-risk abdominal surgery.

Spinal hypotension in obstetrics: Context-sensitive prevention and management

Spinal hypotension during caesarean section remains a common complication, with important attendant maternal and fetal adverse outcomes. Research elucidating the mechanisms of spinal hypotension has led to the development and refinement of effective management strategies, with a particular emphasis on prophylactic vasopressor administration. This has proved effective in well-resourced settings, with maternal comfort and the elimination of nausea now considered the primary aim of treatment. In resource-limited settings, sophisticated strategies are not feasible due to insufficient equipment, staff, and expertise. Therefore, in these areas spinal hypotension remains an important cause of maternal and fetal morbidity and mortality. Translational, context-sensitive research in resource-limited settings has shown promise in implementing pragmatic strategies based on research from resource-rich environments. We review the current best practice for the prevention and treatment of spinal hypotension, with a special emphasis on effective strategies in resource-limited settings. We further suggest a research agenda to address the knowledge gap in specific contexts.

Intravenous infusion route in maternal resuscitation: a scoping review

BACKGROUND

The concept that upper extremities can be used as an infusion route during cardiopulmonary resuscitation in pregnant women is a reasonable recommendation considering the characteristic circulation of pregnant women; however, this method is not based on scientific evidence.

OBJECTIVE OF THE REVIEW

We conducted a scoping review to determine whether the infusion route should be established above the diaphragm during cardiopulmonary resuscitation in a pregnant woman.

DISCUSSION

We included randomized controlled trials (RCTs) and non-RCTs on the infusion of fluids in pregnant women after 20 weeks of gestation requiring establishment of an infusion route due to cardiac arrest, massive bleeding, intra-abdominal bleeding, cesarean section, severe infection, or thrombosis. In total, 3150 articles from electronic database were extracted, respectively. After title and abstract review, 265 articles were extracted, and 116 articles were extracted by full-text screening, which were included in the final analysis. The 116 articles included 78 studies on infusion for pregnant women. The location of the intravenous infusion route could be confirmed in only 17 studies, all of which used the upper extremity to secure the venous route.

CONCLUSION

Pregnant women undergo significant physiological changes that differ from those of normal adults, because of pressure and drainage of the inferior vena cava and pelvic veins by the enlarged uterus. Therefore, despite a lack of evidence, it seems logical to secure the infusion route above the diaphragm when resuscitating a pregnant woman.

Machine Learning, Deep Learning, and Closed Loop Devices-Anesthesia Delivery

With the tremendous volume of data captured during surgeries and procedures, critical care, and pain management, the field of anesthesiology is uniquely suited for the application of machine learning, neural networks, and closed loop technologies. In the past several years, this area has expanded immensely in both interest and clinical applications. This article provides an overview of the basic tenets of machine learning, neural networks, and closed loop devices, with emphasis on the clinical applications of these technologies.

Development of an automated closed-loop β-blocker delivery system to stably reduce myocardial oxygen consumption without inducing circulatory collapse in a canine heart failure model: a proof of concept study

Beta-blockers are well known to reduce myocardial oxygen consumption (MVO₂) and improve the prognosis of heart failure (HF) patients. However, its negative chronotropic and inotropic effects limit their use in the acute phase of HF due to the risk of circulatory collapse. In this study, as a first step for a safe β-blocker administration strategy, we aimed to develop and evaluate the feasibility of an automated β-blocker administration system. We developed a system to monitor arterial pressure (AP), left atrial pressure (P_LA), right atrial pressure, and cardiac output. Using negative feedback of hemodynamics, the system controls AP and P_LA by administering landiolol (an ultra-short-acting β-blocker), dextran, and furosemide. We applied the system for 60 min to 6 mongrel dogs with rapid pacing-induced HF. In all dogs, the system automatically adjusted the doses of the drugs. Mean AP and mean P_LA were controlled within the acceptable ranges (AP within 5 mmHg below target; P_LA within 2 mmHg above target) more than 95% of the time. Median absolute performance error was small for AP [median (interquartile range), 3.1% (2.2–3.8)] and P_LA [3.6% (2.2–5.7)]. The system decreased MVO₂ and P_LA significantly. We demonstrated the feasibility of an automated β-blocker administration system in a canine model of acute HF. The system controlled AP and P_LA to avoid circulatory collapse, and reduced MVO₂ significantly. As the system can help the management of patients with HF, further validations in larger samples and development for clinical applications are warranted.

Detection of arterial pressure waveform error using machine learning trained algorithms

In critically ill and high-risk surgical room patients, an invasive arterial catheter is often inserted to continuously measure arterial pressure (AP). The arterial waveform pressure measurement, however, may be compromised by damping or inappropriate reference placement of the pressure transducer. Clinicians, decision support systems, or closed-loop applications that rely on such information would benefit from the ability to detect error from the waveform alone. In the present study we hypothesized that machine-learning trained algorithms could discriminate three types of transducer error from accurate monitoring with receiver operator characteristic (ROC) curve areas greater than 0.9. After obtaining written consent, patient arterial line waveform data was collected in the operating room in real-time during routine surgery requiring arterial pressure monitoring. Three deliberate error conditions were introduced during monitoring: Damping, Transducer High, and Transducer Low. The waveforms were split up into 10 s clips that were featurized. The data was also either calibrated against the patient's own baseline or left uncalibrated. The data was then split into training and validation sets, and machine-learning algorithms were run in a Monte-Carlo fashion on the training data with variable sized training sets and hyperparameters. The algorithms with the highest balanced accuracy were pruned, then the highest performing algorithm in the training set for each error state (High, Low, Damped) for both calibrated and uncalibrated data was finally tested against the validation set and the ROC and precision-recall curve area-under the curve (AUC) calculated. 38 patients were enrolled in the study with a mean age of 52 ± 15 years. A total of 40 h of monitoring time was recorded with approximately 120,000 heart beats featurized. For all error states, ROC AUCs for algorithm performance on classification of the state were greater than 0.9; when using patient-specific calibrated data AUCs were 0.94, 0.95, and 0.99 for the transducer low, transducer high, and damped conditions respectively. Machine-learning trained algorithms were able to discriminate arterial line transducer error states from the waveform alone with a high degree of accuracy.

Fluid loading therapy to prevent spinal hypotension in women undergoing elective caesarean section: Network meta-analysis, trial sequential analysis and meta-regression

BACKGROUND

Fluid loading is one of the recognised measures to prevent hypotension due to spinal anaesthesia in women scheduled for a caesarean section.

OBJECTIVE

We aimed to evaluate the current evidence on fluid loading in the prevention of spinal anaesthesia-induced hypotension.

DESIGN

Systematic review and network meta-analysis with trial sequential analysis and meta-regression.

DATA SOURCES

Medline, Epub, Embase.com (Embase and Medline), Cochrane Central, Web of Science and Google Scholar were used.

ELIGIBILITY CRITERIA

Only randomised controlled trials were used. Patients included women undergoing elective caesarean section who received either crystalloid or colloid fluid therapy as a preload or coload. The comparator was a combination of either a different fluid or time of infusion.

RESULTS

A total of 49 studies (4317 patients) were included. Network meta-analysis concluded that colloid coload and preload offered the highest chance of success (97 and 67%, respectively). Conventional meta-analysis showed that crystalloid preload is associated with a significantly higher incidence of maternal hypotension than colloid preload: risk ratio 1.48 (95% CI 1.29 to 1.69, P < 0.0001, I = 60%). However, this result was not supported by Trial Sequential Analysis. There was a significant dose-response effect for crystalloid volume preload (regression coefficient = -0.073), which was not present in the analysis of only double-blind studies. There was no dose-response effect for the other fluid regimes.

CONCLUSION

Unlike previous meta-analysies, we found a lack of data obviating an evidence-based recommendation. In most studies, vasopressors were not given prophylactically as is recommended. Studies on the best fluid regimen in combination with prophylactic vasopressors are needed. Due to official european usage restrictions on the most studied colloid (HES), we recommend crystalloid coload as the most appropriate fluid regimen.

TRIAL REGISTRATION

CRD42018099347.

Automated Blood Pressure Control

Arterial pressure management is a crucial task in the operating room and intensive care unit. In high-risk surgical and in critically ill patients, sustained hypotension is managed with continuous infusion of vasopressor agents, which most commonly have direct α agonist activity like phenylephrine or norepinephrine. The current standard of care to guide vasopressor infusion is manual titration to an arterial pressure target range. This approach may be improved by using automated systems that titrate vasopressor infusions to maintain a target pressure. In this article, we review the evidence behind blood pressure management in the operating room and intensive care unit and discuss current and potential future applications of automated blood pressure control.

Norepinephrine prophylaxis for postspinal anesthesia hypotension in parturient undergoing cesarean section: a randomized, controlled trial

OBJECTIVE

To investigate the efficacy and safety of prophylactic infusion of norepinephrine (NE) versus normal saline in patients undergoing cesarean section.

METHODS

Patients (n = 97) were randomized to receive a bolus of NE (6 μg) immediately following spinal anesthesia with maintenance NE (0.05 μg/kg/min IV) or normal saline (n = 98). The primary endpoint was the incidence of postspinal anesthesia hypotension [systolic blood pressure (SBP) < 80% of baseline] at 1-20 min following spinal anesthesia. Secondary outcomes were the overall stability of SBP control versus baseline, inferior vena cava collapsibility index (IVC-CI), other adverse events (bradycardia, nausea, vomiting, and hypertension), and neonatal outcomes (blood gas values and Apgar scores).

RESULTS

The rates of postspinal anesthesia hypotension and severe postspinal anesthesia hypotension (SBP < 60% of the baseline) were significantly lower in the NE group (17.5% vs. 62.2%, p < 0.001; 7.2% vs. 17.4%, p = 0.031). In the NE group, SBP remained more stable and closer to baseline (p < 0.001), and IVC-CI values were lower 5 min after spinal anesthesia and 5 min after fetal delivery (p = 0.045; p < 0.001, respectively). Other adverse effects and neonatal outcomes were not different between the two groups.

CONCLUSION

Prophylactic NE infusion effectively lowers the incidence of postspinal anesthesia hypotension and does not increase other adverse events in patients or neonates.

Remote Surveillance Technologies: Realizing the Aim of Right Patient, Right Data, Right Time

The convergence of multiple recent developments in health care information technology and monitoring devices has made possible the creation of remote patient surveillance systems that increase the timeliness and quality of patient care. More convenient, less invasive monitoring devices, including patches, wearables, and biosensors, now allow for continuous physiological data to be gleaned from patients in a variety of care settings across the perioperative experience. These data can be bound into a single data repository, creating so-called data lakes. The high volume and diversity of data in these repositories must be processed into standard formats that can be queried in real time. These data can then be used by sophisticated prediction algorithms currently under development, enabling the early recognition of patterns of clinical deterioration otherwise undetectable to humans. Improved predictions can reduce alarm fatigue. In addition, data are now automatically queriable on a real-time basis such that they can be fed back to clinicians in a time frame that allows for meaningful intervention. These advancements are key components of successful remote surveillance systems. Anesthesiologists have the opportunity to be at the forefront of remote surveillance in the care they provide in the operating room, postanesthesia care unit, and intensive care unit, while also expanding their scope to include high-risk preoperative and postoperative patients on the general care wards. These systems hold the promise of enabling anesthesiologists to detect and intervene upon changes in the clinical status of the patient before adverse events have occurred. Importantly, however, significant barriers still exist to the effective deployment of these technologies and their study in impacting patient outcomes. Studies demonstrating the impact of remote surveillance on patient outcomes are limited. Critical to the impact of the technology are strategies of implementation, including who should receive and respond to alerts and how they should respond. Moreover, the lack of cost-effectiveness data and the uncertainty of whether clinical activities surrounding these technologies will be financially reimbursed remain significant challenges to future scale and sustainability. This narrative review will discuss the evolving technical components of remote surveillance systems, the clinical use cases relevant to the anesthesiologist's practice, the existing evidence for their impact on patients, the barriers that exist to their effective implementation and study, and important considerations regarding sustainability and cost-effectiveness.

Closed-loop hemodynamic management

As the operating room and intensive care settings become increasingly complex, the required vigilance practitioners must dedicate to a wide array of clinical systems has increased concordantly. The resulting shortage of available attention to these various clinical tasks creates a vacuum for the introduction of systems that can administer well-established goal-directed therapies without significant provider feedback. Recently, there has been an explosion of academic exploration into creating such automated systems, with a strong specific focus on hemodynamic control. Within this field, the largest focus has been on goal-directed fluid therapy as systems automating vasopressor administration have only recently become viable options. Our goal in this review article is to summarize the validity of the relevant goal-directed hemodynamic systems and explore the expanding role of automation within these systems.

Granisetron reduces the need for uterotonics but not sympathomimetics during cesarean delivery

OBJECTIVE

To assess the effect of a 5-hydroxytryptamine-3 receptor antagonist (granisetron) on the use of sympathomimetic (cafedrine/theodrenaline) and uterotonic (oxytocin) agents after spinal anesthesia during cesarean delivery.

METHODS

A retrospective observational analysis was conducted using intraoperative records (n=240) created at a single hospital in Germany between November 1, 2016, and July 31, 2017. The granisetron group (n=120) had received 3 mg of granisetron immediately before induction of spinal anesthesia. The control group (n=120) had not received granisetron. The primary endpoints were the intraoperative requirements for sympathomimetic and uterotonic agents. The secondary endpoints were parameters of intraprocedural maternal hemodynamic and clinical states.

RESULTS

More patients in the granisetron group than in the control group received intraoperative cafedrine/theodrenaline (P=0.045), with the cumulative intraoperative dosage also increased in the granisetron group (P=0.016). By contrast, the cumulative intraoperative dose of oxytocin was lower in the granisetron group than in the control group (P<0.001). Decreases in heart rate and mean arterial blood pressure were lower in the granisetron group versus the control group (P=0.015 and P=0.002, respectively).

CONCLUSION

Treatment with granisetron immediately before cesarean delivery did not reduce the perioperative requirement for sympathomimetics but did reduce the need for uterotonics. REGISTERED AT CLINICALTRIALS.GOV (NCT03318536).

Crystalloid coloading vs. colloid coloading in elective Caesarean section: postspinal hypotension and vasopressor consumption, a prospective, observational clinical trial

BACKGROUND

Maternal hypotension is a common side effect of spinal anaesthesia for Caesarean section. The combination of colloid coloading and vasopressors was considered our standard for its prevention and treatment. As the safety of hydroxyethyl starch is under debate, we replaced colloid with crystalloid coloading.

OBJECTIVE

We hypothesize that the mean blood pressure drop is greater when coloading with crystalloids.

DESIGN

Prospective, observational clinical trial.

SETTING

Two-centre study conducted in Berlin, Germany.

PATIENTS

Parturients scheduled for a Caesarean section were screened for eligibility.

INTERVENTION

The study protocol and patient monitoring were based on the standard operating procedure for Caesarean section in both centres. The data from the crystalloid group were prospectively collected between November 2014 and July 2015.

MAIN OUTCOME MEASURES

The primary endpoint was the median drop in mean blood pressure after induction of spinal anaesthesia. Secondary endpoints were incidence of hypotension (drop > 20% of baseline systolic pressure /drop < 100 mmHg), vasopressor and additional fluid requirements (mL), incidence of bradycardia (heart rate < 60 beats per minute), blood loss, Apgar score, and umbilical artery pH. In case of hypotension, patients received phenylephrine or cafedrine/theodrenaline according to their heart rate. A p < 0.05 was considered significant.

RESULTS

345 prospectively enrolled patients (n = 193 crystalloid group vs. n = 152 colloid group) were analysed. The median drop in mean blood pressure was greater in the crystalloid group [34 mmHg (25; 42 mmHg) vs. 21 mmHg (13; 29 mmHg), p < 0.001]. Incidences of hypotension [93.3% vs. 83.6%, p: 0.004] and bradycardia [19.7% vs. 9.9%, p: 0.012] were also significantly greater in the crystalloid group. Vasopressor requirements, blood loss and neonatal outcome were not different between the groups.

CONCLUSIONS

Crystalloid coloading was associated with a greater drop in mean blood pressure and a higher incidence of hypotension when compared with colloid coloading. Neonatal outcome was, however, unaffected by the type of fluid.

TRIAL REGISTRATION

DRKS00006783 ( http://www.drks.de ).

Computer-controlled closed-loop drug infusion system for automated hemodynamic resuscitation in endotoxin-induced shock

Background

Hemodynamic resuscitation in septic shock requires aggressive fluid replacement and appropriate use of vasopressors to optimize arterial pressure (AP) and cardiac output (CO). Because responses to these drugs vary between patients and within patient over time, strict monitoring of patient condition and repetitive adjustment of drug dose are required. This task is time and labor consuming, and is associated with poor adherence to resuscitation guidelines. To overcome this issue, we developed a computer-controlled closed-loop drug infusion system for automated hemodynamic resuscitation in septic shock, and evaluated the performance of the system in a canine model of endotoxin shock.

Methods

Our system monitors AP, CO and central venous pressure, and computes arterial resistance (R), stressed blood volume (V) and Frank-Starling slope of left ventricle (S). The system controls R with noradrenaline (NA), and V with Ringer’s acetate solution (RiA), thereby controlling AP and CO. In 4 dogs, AP and CO were measured invasively. In another 4 dogs, AP and CO were measured less invasively using clinically acceptable modalities, aiming to make the system clinically feasible. In all 8 dogs, endotoxin shock was induced by injecting Escherichia coli lipopolysaccharide, which significantly decreased AP from 95 (91–108) to 43 (39–45) mmHg, and CO from 112 (104–142) to 62 (51–73) ml·min⁻¹·kg⁻¹. The system was then connected to the dogs, and activated. System performance was observed over a period of 4 h.

Results

Our system immediately started infusions of NA and RiA. Within 40 min, RiA increased V to target level, and NA maintained R at target level, while S was concomitantly increased. These resulted in restoration of AP to 70 (69–71) mmHg and CO to 130 (125–138) ml·min⁻¹·kg⁻¹. Median of absolute performance error, an index of precision of control, was small in AP [2.5 (2.1–4.5) %] and CO [2.4 (1.4–5.5) %], which were not increased even when the variables were measured less invasively.

Conclusions

In a canine model of endotoxin shock, our system automatically improved and maintained AP and CO at their target values with small performance error. Our system is potentially an attractive clinical tool for rescuing patients with septic shock.

Electronic supplementary material

The online version of this article (10.1186/s12871-017-0437-9) contains supplementary material, which is available to authorized users.