Oesophageal Doppler cardiac output monitoring: a longstanding tool with evolving indications and applications

Eight rules for the haemodynamic management of traumatic brain-injured patients

Traumatic brain injury (TBI), a leading cause of death and poor neurological outcomes in trauma patients, is a primary cause of severe disability among survivors and a major public health burden globally. Optimal haemodynamic management is a keystone of care in avoiding secondary brain injury, and contributes to minimising mortality and morbidity. Although some important progress has been achieved, a paucity of high-quality recommendations still exists. The purpose of this article is to review the current knowledge on TBI-associated haemodynamic tenets, in order to summarise the most important aspects of this heterogeneous and complex field.

Cardiac output monitoring - invasive and noninvasive

PURPOSE OF REVIEW

The purpose of this article is to review various contemporary cardiac output (CO) measurement technologies available and their utility in critically ill patients.

RECENT FINDINGS

CO measurement devices can be invasive, minimally invasive, or noninvasive depending upon their method of CO measurement. All devices have pros and cons, with pulmonary artery catheter (PAC) being the gold standard. The invasive techniques are more accurate; however, their invasiveness can cause more complications. The noninvasive devices predict CO via mathematical modeling with several assumptions and are thus prone to errors in clinical situations. Recently, PAC has made a comeback into clinical practice especially in cardiac intensive care units (ICUs). Critical care echocardiography (CCE) is an upcoming tool that not only provides CO but also helps in differential diagnosis. Lack of proper training and nonavailability of equipment are the main hindrances to the wide adoption of CCE.

SUMMARY

PAC thermodilution for CO measurement is still gold standard and most suitable in patients with cardiac pathology and with experienced user. CCE offers an alternative to thermodilution and is suitable for all ICUs; however, structural training is required.

Is there still a role for the oesophageal Doppler in cardiac output monitoring?

The oesophageal Doppler monitor received early endorsement as an effective emerging medical technology, although numerous alternatives have since been widely adopted. This article examines the evidence supporting the continued use of the oesophageal Doppler.

The effects of hemodynamic management using the trend of the perfusion index and pulse pressure variation on tissue perfusion: a randomized pilot study

Background

Intraoperative hemodynamic management is challenging because precise assessment of the adequacy of the intravascular volume is difficult during surgery. Perfusion index (PI) has been shown to reflect changes in peripheral circulation perfusion. Pulse pressure variation (PPV) reflects the preload responsiveness. The hypothesis of this study was that hemodynamic management using the trend of the PI and PPV would improve tissue perfusion.

Methods

This was a prospective, randomized, parallel design, single-blind, single-center pilot study. Patients undergoing elective open gynecological surgery requiring a direct arterial line were included. The patients were randomly allocated to two groups. The intervention group received hemodynamic management using the trend of the PI and PPV in an effort to improve tissue perfusion. The control group received hemodynamic management at the discretion of the anesthesia care provider. The primary outcome was the peak lactate level during surgery. The secondary outcomes were the duration of hypotension, intraoperative fluid balance, intraoperative urine output, and postoperative complication rate. Statistical analysis was performed using Student’s t test and Fisher’s exact test. A P value of < 0.05 was considered statistically significant.

Results

Although the intervention significantly decreased the duration of hypotension and intraoperative fluid balance, the peak lactate level was not different between the intervention group and the control group. Intraoperative urine output and postoperative complication rate were not different between the groups.

Conclusion

Hemodynamic management using the trend of the PI and PPV does not improve tissue perfusion in patients undergoing open gynecological surgery.

Trial registration

This trial was prospectively registered on a publicly accessible database (UMIN Clinical Trials Registry ID: UMIN 000026957. Registered 12 April 2017, https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000030916).

Best practice & research clinical anaesthesiology: Advances in haemodynamic monitoring for the perioperative patient: Perioperative cardiac output monitoring

Less invasive or even completely non-invasive haemodynamic monitoring technologies have evolved during the last decades. Even established, invasive devices such as the pulmonary artery catheter and transpulmonary thermodilution have still an evidence-based place in the perioperative setting, albeit only in special patient populations. Accumulating evidence suggests to use continuous haemodynamic monitoring, especially flow-based variables such as stroke volume or cardiac output to prevent occult hypoperfusion and, consequently, decrease morbidity and mortality perioperatively. However, there is still a substantial gap between evidence provided by randomised trials and the implementation of haemodynamic monitoring in daily clinical routine. Given the fact that perioperative morbidity and mortality are higher than anticipated and anaesthesiologists are in charge to deal with this problem, the recent advances in minimally invasive and non-invasive monitoring technologies may facilitate more widespread use in the operating theatre, as in addition to costs, the degree of invasiveness of any monitoring tool determines the frequency of its application, at least perioperatively. This review covers the currently available invasive, non-invasive and minimally invasive techniques and devices and addresses their indications and limitations.

The Evolution of Surgical Enhanced Recovery Pathways: a Review

PURPOSE OF REVIEW

Enhanced recovery pathways are a well-defined perioperative health care program utilizing evidence-based interventions in a protocol-like manner designed to standardize techniques including drug selection and dosing to improve results and to reduce overall costs including facilitating earlier discharge from hospitals after surgery.

RECENT FINDINGS

A PubMed and World Wide Web search was performed with the following key words: enhanced recovery, surgical enhanced recovery, recovery pathways, and enhanced recovery pathways surgery. This introduction to enhanced recovery pathways reflects its 20-year history, worldwide appeal, and ever growing presence in our practices. Many clinical teams have not, as of yet, incorporated enhanced recovery pathway principles to their practices and therefore, continued evolution should include increasing outreach and formalized guidelines in the future.

Enhanced recovery after surgery: Current research insights and future direction

Since the concept of enhanced recovery after surgery (ERAS) was introduced in the late 1990s the idea of implementing specific interventions throughout the peri-operative period to improve patient recovery has been proven to be beneficial. Minimally invasive surgery is an integral component to ERAS and has dramatically improved post-operative outcomes. ERAS can be applicable to all surgical specialties with the core generic principles used together with added specialty specific interventions to allow for a comprehensive protocol, leading to improved clinical outcomes. Diffusion of ERAS into mainstream practice has been hindered due to minimal evidence to support individual facets and lack of method for monitoring and encouraging compliance. No single outcome measure fully captures recovery after surgery, rather multiple measures are necessary at each stage. More recently the pre-operative period has been the target of a number of strategies to improve clinical outcomes, described as prehabilitation. Innovation of technology in the surgical setting is also providing opportunities to overcome the challenges within ERAS, e.g., the use of wearable activity monitors to record information and provide feedback and motivation to patients peri-operatively. Both modernising ERAS and providing evidence for key strategies across specialties will ultimately lead to better, more reliable patient outcomes.

Goal directed hemodynamic therapy based in esophageal Doppler flow parameters: A systematic review, meta-analysis and trial sequential analysis

BACKGROUND

Numerous studies have compared perioperative esophageal doppler monitoring (EDM) guided intravascular volume replacement strategies with conventional clinical volume replacement in surgical patients. The use of the EDM within hemodynamic algorithms is called 'goal directed hemodynamic therapy' (GDHT).

METHODS

Meta-analysis of the effects of EDM guided GDHT in adult non-cardiac surgery on postoperative complications and mortality using PRISMA methodology. A systematic search was performed in Medline, PubMed, EMBASE, and the Cochrane Library (last update, March 2015).

INCLUSION CRITERIA

Randomized clinical trials (RCTs) in which perioperative GDHT was compared to other fluid management.

PRIMARY OUTCOMES

Overall complications.

SECONDARY OUTCOMES

Mortality; number of patients with complications; cardiac, renal and infectious complications; incidence of ileus. Studies were subjected to quantifiable analysis, pre-defined subgroup analysis (stratified by surgery, type of comparator and risk); pre-defined sensitivity analysis and trial sequential analysis (TSA).

RESULTS

Fifty six RCTs were initially identified, 15 fulfilling the inclusion criteria, including 1,368 patients. A significant reduction was observed in overall complications associated with GDHT compared to other fluid therapy (RR=0.75; 95%CI: 0.63-0.89; P=0.0009) in colorectal, urological and high-risk surgery compared to conventional fluid therapy. No differences were found in secondary outcomes, neither in other subgroups. The impact on preventing the development of complications in patients using EDM is high, causing a relative risk reduction (RRR) of 50% for a number needed to treat (NNT)=6.

CONCLUSIONS

GDHT guided by EDM decreases postoperative complications, especially in patients undergoing colorectal surgery and high-risk surgery. However, no differences versus restrictive fluid therapy and in intermediate-risk patients were found.

Monitoring high-risk patients: minimally invasive and non-invasive possibilities

Over the past decades, there has been considerable progress in the field of less invasive haemodynamic monitoring technologies. Substantial evidence has accumulated, which supports the continuous measurement and optimization of flow-based variables such as stroke volume, that is, cardiac output, in order to prevent occult hypoperfusion and consequently to improve patients' outcome in the perioperative setting. However, there is a striking gap between the developments in haemodynamic monitoring and the increasing evidence to implement defined treatment protocols based on the measured variables, and daily clinical routine. Recent trials have shown that perioperative morbidity and mortality is higher than anticipated. This emphasizes the need for the anaesthesia community to address this issue and promotes the implementation of proven concepts into clinical practice in order to improve patients' outcome, especially in high-risk patients. The advances in minimally invasive and non-invasive monitoring techniques can be seen as a driving force in this respect, as the degree of invasiveness of any monitoring tool determines the frequency of its application, especially in the operating room (OR). From this point of view, we are very confident that some of these minimally invasive and non-invasive haemodynamic monitoring technologies will become an inherent part of our monitoring armamentarium in the OR and in the intensive care unit (ICU).

Using cardiac output monitoring to guide perioperative haemodynamic therapy

PURPOSE OF REVIEW

The aim of this study was to review recent advances and evidence for the use of cardiac output monitors to guide perioperative haemodynamic therapy.

RECENT FINDINGS

There are multiple different cardiac output monitoring devices available for clinical use which are coupled with many different intervention protocols to manipulate perioperative haemodynamics. There is little evidence to demonstrate superiority of any one device. Previous small studies and meta-analyses have suggested that perioperative haemodynamic therapy guided by cardiac output monitoring improves outcomes after major surgery. Despite relatively low-quality evidence several national bodies have recommended 'perioperative goal-directed therapy' (GDT) as a standard of care.Recent larger trials of GDT have mostly failed to prove a benefit of GDT and one explanation for this is the increased quality of usual care that may be occurring because of initiatives such as enhanced recovery after surgery and the WHO Safer Surgery programmes.

SUMMARY

Perioperative GDT remains an exciting intervention to reduce significant morbidity following major surgery; however, it is not yet a proven standard of care. Further large pragmatic trials are required to demonstrate its effectiveness particularly in the era of enhanced recovery after surgery programmes.

Effects of fluid administration on arterial load in septic shock patients

PURPOSE

To determine the effects of fluid administration on arterial load in critically ill patients with septic shock.

METHODS

Analysis of septic shock patients monitored with an oesophageal Doppler and equipped with an indwelling arterial catheter in whom a fluid challenge was performed because of the presence of systemic hypoperfusion. Measures of arterial load [systemic vascular resistance, SVR = mean arterial pressure (MAP)/cardiac output (CO); net arterial compliance, C = stroke volume (SV)/arterial pulse pressure; and effective arterial elastance, Ea = 90% of systolic arterial pressure/SV] were studied both before and after volume expansion (VE).

RESULTS

Eighty-one patients were analysed, 54 (67%) increased their CO by at least 10% after VE (preload responders). In the whole population, 29 patients (36%) increased MAP by at least 10 % from preinfusion level (pressure responders). In the preload responder group, only 24 patients (44%) were pressure responders. Fluid administration was associated with a significant decrease in Ea [from 1.68 (1.11-2.11) to 1.57 (1.08-1.99) mmHg/mL; P = 0.0001] and SVR [from 1035 (645-1483) to 928 (654-1452) dyn s cm(-5); P < 0.01]. Specifically, in preload responders in whom arterial pressure did not change, VE caused a reduction in Ea from 1.74 (1.22-2.24) to 1.55 (1.24-1.86) mmHg/mL (P < 0.0001), affecting both resistive [SVR: from 1082 (697-1475) to 914 (624-1475) dyn s cm(-5); P < 0.0001] and pulsatile [C: from 1.11 (0.84-1.49) to 1.18 (0.99-1.44) mL/mmHg; P < 0.05] components. There was no relationship between preinfusion arterial load parameters and VE-induced increase in arterial pressure.

CONCLUSION

Fluid administration significantly reduced arterial load in critically patients with septic shock and acute circulatory failure, even when increasing cardiac output. This explains why some septic patients increase their cardiac output after fluid administration without improving blood pressure.