Perioperative management of the vulnerable and failing right ventricle

Under recognition combined with suboptimal management of right ventricular (RV) dysfunction and failure is associated with significant perioperative morbidity and mortality. The contemporary perioperative team must be prepared with an approach for early recognition and prompt treatment. In this review, a consensus-proposed scoring system is described to provide a pragmatic approach for expeditious decision-making for these complex patients with a vulnerable RV. Importantly, this proposed scoring system incorporates the context of the planned surgical intervention. Further, as the operating room (OR) represents a unique environment where patients are susceptible to numerous insults, a practical approach to anesthetic management and monitoring both in the OR and in the intensive care unit is detailed. Lastly, an escalating approach to the management of RV failure and options for mechanical circulatory support is provided.

Effect of goal-directed haemodynamic therapy guided by non-invasive monitoring on perioperative complications in elderly hip fracture patients within an enhanced recovery pathway

Background

Goal-directed haemodynamic therapy (GDHT) has been shown to reduce morbidity and mortality in high-risk surgical patients. However, there is little evidence of its efficacy in patients undergoing hip fracture surgery. This study aims to evaluate the effect of GDHT guided by non-invasive haemodynamic monitoring on perioperative complications in patients undergoing hip fracture surgery.

Methods

Patients > 64 years undergoing hip fracture surgery within an enhanced recovery pathway (ERP) were enrolled in this single-centre, non-randomized, intervention study with a historical control group and 12-month follow-up. Exclusion criteria were patients with pathological fractures, traffic-related fractures and refractures. Control group (CG) patients received standard care treatment. Intervention group (IG) patients received a GDHT protocol based on achieving an optimal stroke volume, in addition to a systolic blood pressure > 90 mmHg and an individualized cardiac index. No changes were made between groups in the ERP during the study period. Primary outcome was percentage of patients who developed intraoperative haemodynamic instability. Secondary outcomes were intraoperative arrhythmias, postoperative complications (cardiovascular, respiratory, infectious and renal complications), administered fluids, vasopressor requirements, perioperative transfusion, length of hospital stay, readmission and 1-year survival.

Results

In total, 551 patients (CG=272; IG=279) were included. Intraoperative haemodynamic instability was lower in the IG (37.5% vs 28.0%; p=0.017). GDHT patients had fewer postoperative cardiovascular (18.8% vs 7.2%; p < 0.001), respiratory (15.1% vs 3.6%; p<0.001) and infectious complications (21% vs 3.9%; p<0.001) but not renal (12.1% vs 33.7%; p<0.001). IG patients had less vasopressor requirements (25.5% vs 39.7%; p<0.001) and received less fluids [2.600 ml (IQR 1700 to 2700) vs 850 ml (IQR 750 to 1050); p=0.001] than control group. Fewer patients required transfusion in GDHT group (73.5% vs 44.4%; p<0.001). For IG patients, median length of hospital stay was shorter [11 days (IQR 8 to 16) vs 8 days; (IQR 6 to 11) p < 0.001] and 1-year survival higher [73.4% (95%CI 67.7 to 78.3 vs 83.8% (95%CI 78.8 to 87.7) p<0.003].

Conclusions

The use of GDHT decreases intraoperative complications and postoperative cardiovascular, respiratory and infectious but not postoperative renal complications. This strategy was associated with a shorter hospital stay and increased 1-year survival.

Trial registration

ClinicalTrials.gov NCT02479321.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13741-022-00277-w.

[Resuscitation strategy for patients with sepsis and septic shock]

Fluid and vasopressor resuscitation is, along with antimicrobial therapy and control of the focus of infection, a basic issue of the treatment of sepsis and septic shock. There is currently no accepted protocol that we can follow for the resuscitation of these patients and the Surviving Sepsis Campaign proposes controversial measures and without sufficient evidence support to establish firm recommendations. We propose a resuscitation strategy adapted to the situation of each patient: in the patient in whom community sepsis is suspected, we consider that the early administration of 30mL/kg of crystalloids is effective and safe; in the patient with nosocomial sepsis, we must carry out a more in-depth evaluation before initiating aggressive resuscitation. In patients who do not respond to initial resuscitation, it is necessary to increase monitoring level and, depending on the hemodynamic profile, administer more fluids, a second vasopressor or inotropes.

Noninvasive Beat-To-Beat Stroke Volume Measurements to Determine Preload Responsiveness During Mini-Fluid Challenge in a Swine Model: A Preliminary Study

ABSTRACT

Cardiac output (CO) is an important parameter in fluid management decisions for treating hemodynamically unstable patients in intensive care unit. The gold standard for CO measurements is the thermodilution method, which is an invasive procedure with intermittent results. Recently, electrical impedance tomography (EIT) has emerged as a new method for noninvasive measurements of stroke volume (SV). The objectives of this paper are to compare EIT with an invasive pulse contour analysis (PCA) method in measuring SV during mini-fluid challenge in animals and determine preload responsiveness with EIT. Five pigs were anesthetized and mechanically ventilated. After removing 25% to 30% of the total blood from each animal, multiple fluid injections were conducted. The EIT device successfully tracked changes in SV beat-to-beat during varying volume states, i.e., from hypovolemia and preload responsiveness to target volume and volume overload. From a total of 50 100-mL fluid injections on five pigs (10 injections per pig), the preload responsiveness value was as large as 32.3% in the preload responsiveness state while in the volume overload state it was as low as -4.9%. The bias of the measured SV data using EIT and PCA was 0 mL, and the limits of agreement were ±3.6 mL in the range of 17.6 mL to 51.0 mL. The results of the animal experiments suggested that EIT is capable of measuring beat-to-beat SV changes during mini-fluid challenge and determine preload responsiveness. Further animal and clinical studies will be needed to demonstrate the feasibility of the EIT method as a new tool for fluid management.

The Right Ventricle-You May Forget it, but It Will Not Forget You

Right ventricular (RV) dysfunction and failure are common and often overlooked causes of perioperative deterioration and adverse outcomes. Due to its unique pathophysiologic underpinnings, RV failure often does not respond to typical therapeutic measures such as volume resuscitation and often worsens when therapy is escalated and mechanical ventilation is begun, with a danger of irreversible cardiovascular collapse and death. The single most important factor in improving outcomes in the context of RV failure is anticipating and recognizing it. Once established, a vicious circle of systemic hypotension, and RV ischemia and dilation is set in motion, rapidly spiraling down into a state of shock culminating in multi-organ failure and ultimately death. Therapy of RV failure must focus on rapidly reestablishing RV coronary perfusion, lowering pulmonary vascular resistance and optimizing volemia. In parallel, underlying reversible causes should be sought and if possible treated. In all stages of diagnostics and therapy, echocardiography plays a central role. In severe cases of RV dysfunction there remains a role for the use of the pulmonary artery catheter. When these mostly simple measures are undertaken in a timely fashion, the spiral of death of RV failure can often be broken or even prevented altogether.

Dynamic prediction of fluid responsiveness during positive pressure ventilation: a review of the physiology underlying heart-lung interactions and a critical interpretation

OBJECTIVE

Cardiovascular responses to hypovolemia and hypotension are depressed during general anesthesia. A considerable number of anesthetized and critically ill animals may not benefit hemodynamically from a fluid bolus; therefore, it is important to have measures for accurate prediction of fluid responsiveness. Static measures of preload, such as central venous pressure, do not provide accurate prediction of fluid responsiveness, whereas dynamic measures of cardiovascular function, obtained during positive pressure ventilation, are highly predictive. This review describes key physiological concepts behind heart-lung interactions during positive pressure ventilation, factors that can modify this relationship and provides the basis for a rational interpretation of the information obtained from dynamic measurements, with a focus on pulse pressure variation (PPV).

DATABASE USED

PubMed. Search items used were: heart-lung interaction, positive pressure ventilation, pulse pressure variation, dynamic index of fluid therapy, goal-directed hemodynamic therapy, dogs, cats, pigs, horses and rabbits.

CONCLUSIONS

The veterinary literature suggests that targeting specific PPV thresholds should guide fluid therapy in lieu of conventional assessments. Understanding the physiology of heart-lung interactions during intermittent positive pressure ventilation provides a rational basis for interpreting the literature on dynamic indices of fluid responsiveness, including PPV. Clinical trials are needed to evaluate whether goal-directed fluid therapy based on PPV results in improved outcomes in veterinary patient populations.

Functional hemodynamic tests: a systematic review and a metanalysis on the reliability of the end-expiratory occlusion test and of the mini-fluid challenge in predicting fluid responsiveness

Background

Bedside functional hemodynamic assessment has gained in popularity in the last years to overcome the limitations of static or dynamic indexes in predicting fluid responsiveness. The aim of this systematic review and metanalysis of studies is to investigate the reliability of the functional hemodynamic tests (FHTs) used to assess fluid responsiveness in adult patients in the intensive care unit (ICU) and operating room (OR).

Methods

MEDLINE, EMBASE, and Cochrane databases were screened for relevant articles using a FHT, with the exception of the passive leg raising. The QUADAS-2 scale was used to assess the risk of bias of the included studies. In-between study heterogeneity was assessed through the I² indicator. Bias assessment graphs were plotted, and Egger’s regression analysis was used to evaluate the publication bias. The metanalysis determined the pooled area under the receiving operating characteristic (ROC) curve, sensitivity, specificity, and threshold for two FHTs: the end-expiratory occlusion test (EEOT) and the mini-fluid challenge (FC).

Results

After text selection, 21 studies met the inclusion criteria, 7 performed in the OR, and 14 in the ICU between 2005 and 2018. The search included 805 patients and 870 FCs with a median (IQR) of 39 (25–50) patients and 41 (30–52) FCs per study. The median fluid responsiveness was 54% (45–59). Ten studies (47.6%) adopted a gray zone analysis of the ROC curve, and a median (IQR) of 20% (15–51) of the enrolled patients was included in the gray zone. The pooled area under the ROC curve for the end-expiratory occlusion test (EEOT) was 0.96 (95%CI 0.92–1.00). The pooled sensitivity and specificity were 0.86 (95%CI 0.74–0.94) and 0.91 (95%CI 0.85–0.95), respectively, with a best threshold of 5% (4.0–8.0%). The pooled area under the ROC curve for the mini-FC was 0.91 (95%CI 0.85–0.97). The pooled sensitivity and specificity were 0.82 (95%CI 0.76–0.88) and 0.83 (95%CI 0.77–0.89), respectively, with a best threshold of 5% (3.0–7.0%).

Conclusions

The EEOT and the mini-FC reliably predict fluid responsiveness in the ICU and OR. Other FHTs have been tested insofar in heterogeneous clinical settings and, despite promising results, warrant further investigations.

Electronic supplementary material

The online version of this article (10.1186/s13054-019-2545-z) contains supplementary material, which is available to authorized users.

Anesthesia-Associated Relative Hypovolemia: Mechanisms, Monitoring, and Treatment Considerations

Although the utility and benefits of anesthesia and analgesia are irrefutable, their practice is not void of risks. Almost all drugs that produce anesthesia endanger cardiovascular stability by producing dose-dependent impairment of cardiac function, vascular reactivity, and compensatory autoregulatory responses. Whereas anesthesia-related depression of cardiac performance and arterial vasodilation are well recognized adverse effects contributing to anesthetic risk, far less emphasis has been placed on effects impacting venous physiology and venous return. The venous circulation, containing about 65–70% of the total blood volume, is a pivotal contributor to stroke volume and cardiac output. Vasodilation, particularly venodilation, is the primary cause of relative hypovolemia produced by anesthetic drugs and is often associated with increased venous compliance, decreased venous return, and reduced response to vasoactive substances. Depending on factors such as patient status and monitoring, a state of relative hypovolemia may remain clinically undetected, with impending consequences owing to impaired oxygen delivery and tissue perfusion. Concurrent processes related to comorbidities, hypothermia, inflammation, trauma, sepsis, or other causes of hemodynamic or metabolic compromise, may further exacerbate the condition. Despite scientific and technological advances, clinical monitoring and treatment of relative hypovolemia still pose relevant challenges to the anesthesiologist. This short perspective seeks to define relative hypovolemia, describe the venous system’s role in supporting normal cardiovascular function, characterize effects of anesthetic drugs on venous physiology, and address current considerations and challenges for monitoring and treatment of relative hypovolemia, with focus on insights for future therapies.

Contemporary Approaches to Perioperative IV Fluid Therapy

BACKGROUND

Intravenous fluid therapy is required for most surgical patients, but inappropriate regimens are commonly prescribed. The aim of this narrative review was to provide evidence-based guidance on appropriate perioperative fluid management.

METHOD

We did a systematic literature search of the literature to identify relevant studies and meta-analyses to develop recommendations.

RESULTS

Of 275 retrieved articles, we identified 25 articles to inform this review. "Normal" saline (0.9% sodium chloride) is not physiological and can result in sodium overload and hyperchloremic acidosis. Starch colloid solutions are not recommended in surgical patients at-risk of sepsis or renal failure. Most surgical patients can have clear fluids and/or administration of carbohydrate-rich drinks up to 2 h before surgery. An intraoperative goal-directed fluid strategy may reduce postoperative complications and reduce hospital length of stay. Regular postoperative assessment of the patient's fluid status and requirements should include looking for physical signs of dehydration or hypovolemia, or fluid overload. Both hypovolemia and salt and water overload lead to adverse events, complications and prolonged hospital stay. Urine output can be an unreliable indicator of hydration status in the postoperative surgical patient. Excess fluid administration has been linked to acute kidney injury, gastrointestinal dysfunction, and cardiac and pulmonary complications.

CONCLUSION

There is good evidence supporting the avoidance of unnecessary fasting and the value of an individualized perioperative IV fluid regimen, with transition to oral fluids as soon as possible, to help patients recover from major surgery.

A rational approach to fluid therapy in sepsis

Aggressive fluid resuscitation to achieve a central venous pressure (CVP) greater than 8 mm Hg has been promoted as the standard of care, in the management of patients with severe sepsis and septic shock. However recent clinical trials have demonstrated that this approach does not improve the outcome of patients with severe sepsis and septic shock. Pathophysiologically, sepsis is characterized by vasoplegia with loss of arterial tone, venodilation with sequestration of blood in the unstressed blood compartment and changes in ventricular function with reduced compliance and reduced preload responsiveness. These data suggest that sepsis is primarily not a volume-depleted state and recent evidence demonstrates that most septic patients are poorly responsive to fluids. Furthermore, almost all of the administered fluid is sequestered in the tissues, resulting in severe oedema in vital organs and, thereby, increasing the risk of organ dysfunction. These data suggest that a physiologic, haemodynamically guided conservative approach to fluid therapy in patients with sepsis would be prudent and would likely reduce the morbidity and improve the outcome of this disease.