Determination of cardiovascular parameters in burn patients using arterial waveform analysis: A review

Early Autocalibrated Arterial Waveform Analysis for the Management of Burn Shock-A Cohort Study

Adequate fluid therapy is crucial for resuscitation after major burns. To adapt this to individual patient demands, standard is adjustment of volume to laboratory parameters and values of enhanced hemodynamic monitoring. To implement calibrated parameters, patients must have reached the intensive care unit (ICU). The aim of this study was, to evaluate the use of an auto-calibrated enhanced hemodynamic monitoring device to improve fluid management before admission to ICU. We used PulsioflexProAqt® (Getinge) during initial treatment and burn shock resuscitation. Analysis was performed regarding time of measurement, volume management, organ dysfunction, and mortality. We conducted a monocentre, prospective cohort study of 20 severely burned patients, >20% total body surface area (TBSA), receiving monitoring immediately after admission. We compared to 57 patients, matched in terms of TBSA, age, sex, and existence of inhalation injury out of a retrospective control group, who received standard care. Hemodynamic measurement with autocalibrated monitoring started significantly earlier: 3.75(2.67-6.0) hours (h) after trauma in the study group versus 13.6(8.1-17.5) h in the control group (P < .001). Study group received less fluid after 6 h: 1.7(1.2-2.2) versus 2.3(1.6-2.8) ml/TBSA%/kg, P = .043 and 12 h: 3.0(2.5-4.0) versus 4.2(3.1-5.0) ml/TBSA%/kg, P = .047. Dosage of norepinephrine was higher after 18 h in the study group: 0.20(0.12-0.3) versus 0.08(0.02-0.18) µg/kg/min, P = .014. The study group showed no adult respiratory distress syndrome versus 21% in the control group, P = .031. There was no difference in other organ failures, organ replacement therapy, and mortality. The use of auto-calibrated enhanced hemodynamic monitoring is a fast and feasible way to guide early fluid therapy after burn trauma. It reduces the time to reach information about patient's volume capacity. Management of fluid application changed to a more restrictive fluid use in the early period of burn shock and led to a reduction of pulmonary complications.

Measurements of Cardiac Output and Management of Blood Transfusions During Burn Surgery-An Observational Prospective Study

Burn surgery can cause extensive bleeding, which lead to perioperative blood transfusions. The purpose of this study was to investigate whether blood transfusions during burn surgery, guided by standard monitoring with inspection of the operative field, measurements of blood pressure, heart rate, hourly diuresis, and concentrations of hemoglobin and lactate could sustain the preoperative cardiac output (CO) till end of surgery. We investigated 15 patients ≥18 years of age scheduled for burn surgery, where the perioperative monitoring included an arterial line. After induction of anesthesia and before start of surgery, we measured baseline values of CO with the minimally invasive LiDCOrapid, mean arterial pressure, and concentrations of hemoglobin and lactate in arterial blood. We measured these values every 30 minutes through surgery. The primary outcome was change in CO from baseline till end of surgery. Secondary outcomes included the change in concentrations of hemoglobin and lactate from baseline till end of surgery. We found no statistically significant change in CO from baseline till end of surgery (6.6 [±2.4] liters/min; 7.2 [±3.2] liters/min; P = .26). We found a statistically significant decrease in concentration of hemoglobin (7.2 [±0.8] mmol/liter; 6.2 [±0.9] mmol/liter; P = .0002), and a statistically significant increase in concentration of lactate (1.3 [±0.5] mmol/liter; 1.7 [±1] mmol/liter; P = .02). The perioperative blood transfusion guided by standard monitoring seemed to sustain CO from baseline till end of surgery; however, further research is needed to confirm this.

A noninvasive computational method for fluid resuscitation monitoring in pediatric burns: a preliminary report

The fluid resuscitation needs of children with small area burns are difficult to predict. The authors hypothesized that a novel computational algorithm called the compensatory reserve index (CRI), calculated from the photoplethysmogram waveform, would correlate with percent total body surface area (%TBSA) and fluid administration in children presenting with ≤20% TBSA burns. The authors recorded photoplethysmogram waveforms from burn-injured children that were later processed by the CRI algorithm. A CRI of 1 represents supine normovolemia; a CRI of 0 represents the point at which a subject is predicted to experience hemodynamic decompensation. CRI values from the first 10 minutes of monitoring were compared to clinical data. Waveform data were available for 27 children with small to moderate sized burns (4-20 %TBSA). The average age was 6.3 ± 1.1 years, the average %TBSA was 10.4 ± 0.8%, and the average CRI was 0.36 ± 0.03. CRI inversely correlated with the %TBSA (P < .001). Twenty children were transferred with an average reported %TBSA of 16.5 ± 1.4%, which was significantly higher than the actual %TBSA (P < .001). CRI correlated better with actual %TBSA compared to reported %TBSA (P = .02). CRI correlated with the amount of fluid resuscitation given at the time of CRI measurement (P = .02) and was inversely related to total fluids given per 24 hours for children with adequate urine output (>0.5 ml/kg/hr) (P < .001). The CRI is decreased in children with small to moderate size burns, and correlates with %TBSA and fluid administration. This suggests that the CRI may be useful for fluid resuscitation guidance, warranting further study.

Critical care of burn patients. New approaches to old problems

Recent publications on treatment options in critically ill patients change beliefs and clinical behaviors. Many dogmas, which the modern management of critical illness relies on, have been questioned. These publications (consensus articles, reviews, meta-analysis and original papers) concern some fundamental issues of critical care: interventions in acute respiratory distress syndrome (ARDS), hemodynamic monitoring, glucose control and nutritional support and revise our views on many key points of critical care of burn patients.

A new marker of sepsis post burn injury?*

OBJECTIVES

Accurate diagnosis of sepsis is difficult in patients post burn due to the large inflammatory response produced by the major insult. We aimed to estimate the values of serum N-terminal pro-B-type natriuretic peptide and procalcitonin and the changes in hemodynamic variables as markers of sepsis in critically ill burn patients.

DESIGN

Prospective, observational study.

SETTING

A quaternary-level university-affiliated ICU.

PATIENTS

Fifty-four patients with burns to total body surface area of greater than or equal to 15%, intubated with no previous cardiovascular comorbidities, were enrolled.

INTERVENTIONS

At admission, a FloTrac/Vigileo system was attached and daily blood samples taken from the arterial catheter. Infection surveillance was carried out daily with patients classified as septic/nonseptic according to American Burns Consensus criteria.

MEASUREMENTS AND MAIN RESULTS

N-terminal pro-B-type natriuretic peptide, procalcitonin, and waveform analysis of changes in stroke volume index and systemic vascular resistance index were measured within the first 24 hours after burn and daily thereafter for the length of the ICU stay or until their first episode of sepsis. Prevalences of stroke volume variation less than 12% (normovolemia) with hypotension (systolic blood pressure < 90 mm Hg) were recorded. Patients with sepsis differed significantly from "no sepsis" for N-terminal pro-B-type natriuretic peptide, systemic vascular resistance index, and stroke volume index on days 3-7. Procalcitonin did not differ between sepsis and "no sepsis" except for day 3. Area under the receiver operating characteristic curves showed excellent discriminative power for B-type natriuretic peptide (p = 0.001; 95% CI, 0.99-1.00), systemic vascular resistance index (p < 0.001; 95% CI, 0.97-0.99), and stroke volume index (p < 0.01; 95% CI, 0.96-0.99) in predicting sepsis but not for procalcitonin (not significant; 95% CI, 0.29-0.46). A chi-square crosstab found that there was no relationship between hypotension with normovolemia (stroke volume variation < 12%) and sepsis.

CONCLUSIONS

Serum N-terminal pro-B-type natriuretic peptide levels and certain hemodynamic changes can be used as an early indicator of sepsis in patients with burn injury. Procalcitonin did not assist in the early diagnosis of sepsis.

Place of the colloids in fluid resuscitation of the traumatized patient

PURPOSE OF REVIEW

The examination of the recent literature aimed at analysing the most recent data that could affect decisions regarding the use of colloids in trauma resuscitation.

RECENT FINDINGS

Animal data have generally shown a beneficial effect of colloids in trauma resuscitation, with improvements in capillary leak demonstrated in lung, intestine and brain. In most studies, hydroxyethyl starch resuscitation was more effective than crystalloid and decreased markers of inflammatory processes were observed. Brain injury in animals was attenuated with colloids. In uncontrolled haemorrhage, resuscitation with colloid increased bleeding and mortality.Human studies have also failed to confirm the suggestion that albumin resuscitation may be associated with a worse outcome in head injury. However, there is a strong suggestion that aggressive prehospital resuscitation, particularly with colloid, may be harmful. Studies in burns have consistently shown an improvement in the tendency to fluid overload with the inclusion of colloid in the resuscitation strategy, but so far no outcome benefit has been shown.Two studies of general trauma resuscitation have shown apparent benefit from the use of HES in early resuscitation with reductions in mortality and in renal injury.

SUMMARY

Recent trauma studies provide ongoing, but not conclusive, evidence of a benefit from colloid resuscitation in trauma.

Evaluation of arterial waveform derived variables for an assessment of volume resuscitation in mechanically ventilated burn patients

OBJECTIVE

The purpose of this study was to assess the usefulness of stroke volume variations to monitor the early fluid resuscitation in mechanically ventilated burn ICU patients.

METHODS AND RESULTS

Data of 29 burn patients (APACHE II - 9.8±3.6, SAPS II - 29±5, TBSA - 39.5±14) were prospectively included in this observational study. Hemodynamic parameters were determined using arterial pressure wave analysis for up to 36h after burn. Statistically significant changes in cardiac index (CI), systemic vascular resistance index (SVRI), stroke volume variation (SVV) were recorded during the observation period. There were significant correlations between CI and SVV (r=-0.454, p=0.03), SVV and SVRI (r=0.482, p=0.02) at 16 h postburn; CI and SVV (r=-0.513, p=0.012), SVV and SVRI (r=0.480, p=0.02) at 24 h postburn, CI and SVV at 36 h postburn (r=-0.478, p=0.021). Significant changes in CI (1.9±1 vs. 3.4±0.9), p=0.02 and in SVV (24.9±3 vs. 14.6±2, p=0.01) were observed in patients with low cardiac output state after administration of 10 ml/kg of Ringer lactate.

CONCLUSION

Our results suggest that measurement of stroke volume variations by arterial pulse contour analysis is valuable in monitoring volume administration and in predicting volume responsiveness during the early postburn period.