Left ventricular performance in patients with thermal injury or multiple trauma: a clinical study with echocardiography

Is There a Role for Transesophageal Echocardiography in the Perioperative Trauma Patient?

Purpose of Review

This review article summarizes the advantages and potential uses of focused transesophageal echocardiography (TEE) in the perioperative period for trauma patients. We suggest a locally developed TEE protocol for trauma and provide strategies to achieve widespread use of TEE in the anesthesia care of trauma patients.

Recent Findings

In recent years, TEE has gained interest as an additional modality as point-of-care ultrasound (POCUS) for the resuscitation of acutely ill patients in whom transthoracic echocardiography is not feasible or non-diagnostic. Nevertheless, its use among non-cardiac anesthesiologists is still limited compared to the more traditional POCUS applications.

Summary

A goal-directed, focused TEE can be performed at the bedside in different locations and mechanically ventilated patients. TEE provides relevant diagnostic information to guide the resuscitation of acutely injured patients, particularly to identify life-threatening hidden thoracic injuries in the scenario of patients with multi-system trauma.

Burn resuscitation--hourly urine output versus alternative endpoints: a systematic review

Controversy remains over appropriate endpoints of resuscitation during fluid resuscitation in early burns management. We reviewed the evidence as to whether utilizing alternative endpoints to hourly urine output produces improved outcomes. MEDLINE, CINAHL, EMBASE, Cochrane Library, Web of Science, and full-text clinicians' health journals at OVID, from 1990 to January 2014, were searched with no language restrictions. The keywords burns AND fluid resuscitation AND monitoring and related synonyms were used. Outcomes of interest included all-cause mortality, organ dysfunction, length of stay (hospital, intensive care), time on mechanical ventilation, and complications such as incidence of pulmonary edema, compartment syndromes, and infection. From 482 screened, eight empirical articles, 11 descriptive studies, and one systematic review met the criteria. Utilization of hemodynamic monitoring compared with hourly urine output as an endpoint to guide resuscitation found an increased survival (risk ratio [RR], 0.58; 95% confidence interval, 0.42-0.85; P < 0.004), with no effect on renal failure (RR, 0.77; 95% confidence interval, 0.39-1.43; P = 0.38). However, inclusion of the randomized controlled trials only found no survival advantage of hemodynamic monitoring over hourly urine output (RR, 0.72; 95% confidence interval, 0.43-1.19; P = 0.19) for mortality. There were conflicting findings between studies for the volume of resuscitation fluid, incidence of sepsis, and length of stay. There is limited evidence of increased benefit with utilization of hemodynamic monitoring, however, all studies lacked assessor blinding. A large multicenter study with a priori-determined subgroup analysis investigating alternative endpoints of resuscitation is warranted.

A protocol for resuscitation of severe burn patients guided by transpulmonary thermodilution and lactate levels: a 3-year prospective cohort study

Introduction

The use of urinary output and vital signs to guide initial burn resuscitation may lead to suboptimal resuscitation. Invasive hemodynamic monitoring may result in over-resuscitation. This study aimed to evaluate the results of a goal-directed burn resuscitation protocol that used standard measures of mean arterial pressure (MAP) and urine output, plus transpulmonary thermodilution (TPTD) and lactate levels to adjust fluid therapy to achieve a minimum level of preload to allow for sufficient vital organ perfusion.

Methods

We conducted a three-year prospective cohort study of 132 consecutive critically burned patients. These patients underwent resuscitation guided by MAP (>65 mmHg), urinary output (0.5 to 1 ml/kg), TPTD and lactate levels. Fluid therapy was adjusted to achieve a cardiac index (CI) >2.5 L/minute/m² and an intrathoracic blood volume index (ITBVI) >600 ml/m², and to optimize lactate levels. Statistical analysis was performed using mixed models. We also used Pearson or Spearman methods and the Mann-Whitney U-test.

Results

A total of 98 men and 34 women (mean age, 48 ± 18 years) was studied. The mean total body surface area (TBSA) burned was 35% ± 22%. During the early resuscitation phase, lactate levels were elevated (2.58 ± 2.05 mmol/L) and TPTD showed initial hypovolemia by the CI (2.68 ± 1.06 L/minute/m²) and the ITBVI (709 ± 254 mL/m²). At 24 to 32 hours, the CI and lactic levels were normalized, although the ITBVI remained below the normal range (744 ± 276 ml/m²). The mean fluid rate required to achieve protocol targets in the first 8 hours was 4.05 ml/kg/TBSA burned, which slightly increased in the next 16 hours. Patients with a urine output greater than or less than 0.5 ml/kg/hour did not show differences in heart rate, mean arterial pressure, CI, ITBVI or lactate levels.

Conclusions

Initial hypovolemia may be detected by TPTD monitoring during the early resuscitation phase. This hypovolemia might not be reflected by blood pressure and hourly urine output. An adequate CI and tissue perfusion can be achieved with below-normal levels of preload. Early resuscitation guided by lactate levels and below-normal preload volume targets appears safe and avoids unnecessary fluid input.

Myocardial function and haemodynamics in extensive burn trauma: evaluation by clinical signs, invasive monitoring, echocardiography and cytokine concentrations. A prospective clinical study

BACKGROUND

The objectives of this study were to (1). describe the haemodynamic profile of patients with extensive burns during the early fluid resuscitation phase, (2). evaluate myocardial performance by invasive monitoring and echocardiography and (3). analyze the relations between serum cytokine (IL-6, IL-8, TNF) and natriuretic peptide (ANP, BNP) concentrations and myocardial function in these patients.

METHODS

Prospective, clinical study in a tertiary care burn centre. Invasive haemodynamic measurements including a pulmonary artery catheter, echocardiography, blood samples for cytokine and atriopeptide analyses. The follow-up time was up to 72 h postinjury.

RESULTS

According to echocardiography, patients were hypovolaemic despite aggressive (median 7,9 ml kg(-1) h(-1), range 3.3-11.7) fluid resuscitation and adequate urine output (median 0.9 ml kg(-1) h(-1), range 0.46-1.35) during the first day postinjury. There were no consistent findings of hyperlactatemia, metabolic acidosis or low mixed venous oxygen saturations. Daily highest and lowest values of cardiac index and stroke volume index increased and the lowest and highest values of systemic vascular resistance decreased. Cardiac performance (stroke volume index) improved during the study period even though there were no initial signs of myocardial depression in echocardiography. Three patients received a dobutamine infusion based on clinical judgement. There was no consistent association between haemodynamic changes and plasma cytokine concentrations.

CONCLUSION

Persisting hypovolaemia is evident in the resuscitation phase of extensive burns despite aggressive fluid therapy and the lack of classic signs of hypoperfusion. Cardiac performance improves during the first days after extensive burn injury without association with plasma cytokine profile.

Systemic hemodynamics, gastric intramucosal PCO2 changes, and outcome in critically ill burn patients

OBJECTIVES

To define the hemodynamic and gastric intramucosal PCO2 (PiCO2) changes during the first 48 hrs after burn trauma and to analyze their relationship with outcome.

DESIGN

Prospective, observational study in a cohort of consecutively admitted critically ill burn patients.

SETTING

Intensive care burn unit in a university hospital.

PATIENTS

Forty-two patients with burns covering >20% of body surface area or inhalation injury.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Patients were monitored with an oximetric pulmonary arterial catheter and a gastric tonometer to measure PiCO2. The difference between arterial and gastric mucosal PCO2 (P[i-a]CO2) was considered indicative of gastric mucosal hypoxia. Hemodynamic and PiCO2 measurements were performed during the first 48 hrs after admission. Patients suffered burns covering 36.1% +/- 14.3% (mean +/- SD) and 45.3% +/- 21.9% of body surface area (survivors and nonsurvivors, respectively). All patients were successfully resuscitated by conventional standards. Nonsurvivors (n = 16) died a median of 17 days after admission. In univariate analysis, the presence of shock during the resuscitation phase, age, mixed venous pH, P[i-a]CO2, right atrial pressure, pulmonary arterial pressure, pulmonary arterial occlusion pressure, cardiac index, systemic and pulmonary vascular resistance, left ventricular stroke work index, mixed venous oxygen saturation, and systemic oxygen delivery, consumption, and extraction ratio, measured over the first 12 hrs after admission, were significantly (p < .05) different between survivors and nonsurvivors. These differences disappeared after 12 hrs after admission. Multivariate analysis identified age, percentage body surface area burned, and oxygen delivery index (6 hrs after admission) as factors independently associated with a poor outcome. P[i-a]CO2 (12 hrs after admission) was significantly greater in patients with than in those without inhalation injury (17 +/- 13 torr [2.26 +/- 1.73 kPa] vs. 6 +/- 10 torr [0.79 +/- 1.33 kPa]; p = .005). Patients with a P[i-a]CO2 difference (6 hrs after admission) > or =10 torr (1.33 kPa) had a mortality rate of 56% vs. 25% of those patients with <10 torr (p = .044).

CONCLUSIONS

Our data indicate that there are hemodynamic and biochemical changes that occur early after burn trauma that are associated with prognosis after an apparently successful resuscitation. Particularly, a hemodynamic profile characterized by systemic acidosis, low systemic blood flow, and systemic and pulmonary vasoconstriction early after trauma is associated with a poor outcome. Additionally, intestinal mucosal acidosis occurs after burn trauma, is influenced by inhalation injury, and is a variable related to outcome.

Changes in left ventricular performance in patients with severe head injury during and after mild hypothermia

OBJECTIVE

To evaluate left ventricular (LV) performance in patients with severe head injury during and after mild hypothermia.

PATIENTS AND METHODS

Seven consecutive patients who underwent therapeutic mild hypothermia (age, 15 to 70 years; Glasgow Coma Scale score on admission, 4 to 8). LV performance was assessed by using M-mode, color tissue Doppler imaging tracings and pulsed Doppler echocardiography. LV contraction and relaxation were evaluated by using the peak velocity of LV posterior wall movement during systole (Smax) and diastole (Dmax), respectively, in addition to the conventional echocardiographic indices.

RESULTS

Mild hypothermia increased LV ejection time and reciprocally reduced LV filling period as indicated by temperature-dependent shortening of the early diastolic filling and the total diastolic inflow time. The indices depending on temporal factors such as ejection time, Smax, or Dmax were significantly affected by mild hypothermia, whereas those depending on spatial factors such as fractional shortening or stroke volume index were not. The attenuated Smax was compensated for the prolonged ejection time resulting in the relatively consistent fractional shortening regardless of body temperature. There was no compensatory mechanism for the decreased Dmax during diastole.

CONCLUSION

The effect of mild hypothermia seemed to be predominantly negatively chronotropic. LV diastolic function was more vulnerable to mild hypothermia than LV systolic function was.

Transesophageal echocardiography in the evaluation of cardiothoracic trauma

TEE has been used in the past 13 years to examine the heart and thoracic aorta, and recently the clinical utility of TEE has greatly expanded to include its use in a variety of thoracic trauma injuries. We retrospectively reviewed the use of TEE in our institution from June 1994 to June 1995. Sixteen patients underwent TEE for a variety of indications, including traumatic aortic dissection, penetrating wounds to the precordium, retrieval of a foreign body, valvular trauma, and postoperative evaluation of cardiac repair. TEE affected patient treatment decisions in all of these cases. As a diagnostic modality and as a guide to specific therapy, TEE was safe, expedient, accurate, and highly valuable in the evaluation of patients with trauma to the heart or great vessels.

The complexities of managing severe burns with associated trauma

A high incidence of severe inhalation injuries can be expected in the combined injury patient. The initial management remains attention to the ATLS priorities of airway, breathing, and circulation, with prompt and safe transfer to a regional center of excellence. The treatment of either the burn or the associated injuries may be compromised by their combined presence, and a team approach is essential to their optimal management. Circulatory management goals based on oxygen consumption and delivery allow greater understanding and control of the physiologic demands placed on the patient by the disease process. The management of inhalation injury and ARDS is at an exciting turning point in history, and we now have in hand and use many techniques that allow salvage of these mortal conditions. Pain management is essential to humane care and requires frequent assessment and patient control to be effective. Rehabilitation of the burn and trauma patient starts on the day of injury and requires team dedication to the areas of greatest morbidity early in the planning of surgical priorities and physical therapy.

Left ventricular function after severe trauma

OBJECTIVE

To evaluate cardiac function at the early phase of severe trauma.

DESIGN

Prospective, clinical study.

SETTING

Anesthesiological Intensive Care Unit.

PATIENTS

7 consecutive patients admitted after severe trauma (ISS: 38 +/- 9, mean +/- SD), without preexisting cardiac disease.

INTERVENTIONS

Each patient received midazolam and sufentanyl for sedation. Right heart catheterization (Swan-Ganz) and transesophageal echocardiography (TEE) were performed. The fractional area change (FAC) of the left ventricle was calculated within 6 h following trauma and at day 1 and day 2 in order to evaluate left ventricular function.

MEASUREMENTS AND RESULTS

All of the patients had a low FAC value < 50% at day 0 (43.2 +/- 2.4%, range 39-46%), which increased significantly at day 2 (52.5 +/- 4%, range 47-59%, p = 0.001), whereas heart rate and preload (assessed by left ventricular end diastolic area and pulmonary arterial occlusion pressure) were constant and afterload, assessed by systolic blood pressure, increased significantly between day 0 and day 2 (112 +/- 21 to 145 +/- 24 mmHg, p = 0.02).

CONCLUSION

The initial phase of severe trauma is associated with an abnormal cardiac function, suggested by a low FAC value. This myocardial dysfunction must be taken into account for early resuscitation after severe injury.

Burn injury alters beta-adrenergic receptor and second messenger function in rat ventricular muscle

OBJECTIVES

The molecular pharmacologic bases for the attenuated cardiovascular and metabolic responses to catecholamines, after burn injury, have not been elucidated. In the present study, myocardial tissues were used as a model of beta-adrenergic receptors to study burn injury-induced alterations in receptors and in signal transduction.

DESIGN

Prospective study, randomized to treatment and control groups.

SETTING

University-hospital research laboratory.

SUBJECTS

Male Sprague-Dawley rats (180 to 210 g).

INTERVENTIONS

A 50% body surface area burn or sham-burn was administered to the rats.

MEASUREMENTS AND MAIN RESULTS

Myocardial membranes were isolated at 24 hrs, 7 days and 14 days after 50% body surface area scald or sham injury. (-)125I-iodocyanopindolol was used to assess maximal binding capacity and affinity of the beta-adrenergic receptor. Basal and stimulated concentrations of second messenger, cyclic adenosine monophosphate (cAMP), were also assessed. Production of cAMP during isoproterenol stimulation tested the integrity of the beta-adrenergic receptor-mediated signal transduction. Forskolin, which stimulates adenylate cyclase enzyme directly (bypassing the receptor and G protein) to produce cAMP, tested the efficacy of the enzyme itself. Maximal binding capacity was unaltered between the experimental and control groups, but the affinity (mean +/- SEM) was significantly decreased in burned animals at 7 days (125.4 +/- 15.5 picomoles [pmol]; p = .01) and at 14 days (216.7 +/- 50.7 pmol; p = .001) compared with controls (75.5 +/- 8.4 pmol). In different set experimental and control groups, basal concentrations of cAMP in myocardial membranes were significantly decreased in burned animals at 7 days (control 38.6 +/- 4.2 vs. 5.8 +/- 0.9 pmol/mg of protein/min; p = .003) and at 14 days (control 47.4 +/- 3.2 vs 28.3 +/- 6.6 pmol/mg of protein/min; p = .002). The forskolin (direct)-stimulated synthesis of cAMP was decreased in burned animals at 24 hrs (control 339.0 +/- 40.5 vs. 214.4 +/- 16.6 pmol/mg of protein/min; p = .01), at 7 days (control 289.0 +/- 34.4 vs. 32 +/- 13.0 pmol/mg of protein/min; p = .01), and at 14 days (control 322.9 +/- 28.6 vs. 137.0 +/- 46.1 pmol/mg of protein/min; p = .01). The isoproterenol or receptor-mediated stimulation of cAMP production was also significantly (p < .001) impaired in burned animals compared with controls at 24 hrs (control 134.7 +/- 11.9 vs. 83.1 +/- 13.3 pmol/mg of protein/min), and at 14 days (control 128.2 +/- 7.2 vs. 92.8 +/- 17.7 pmol/mg of protein/min).

CONCLUSION

The etiology of the decreased responses in the myocardium to exogenous and endogenous beta-adrenergic receptor agonists after burn injury may be attributed to decreased affinity for ligands, and also to impaired receptor-mediated signal transduction and to decreased adenylate cyclase enzyme activity, resulting in decreased basal and stimulated second messenger (cAMP) production.