A pig model for blunt chest trauma: no pulmonary edema in the early phase.

OBJECTIVE: Chest trauma remains a leading cause of trauma-death. Since lung contusion is one of the most important lesions implicated, the aim of this experimental study was to evaluate the cardiorespiratory consequences of an isolated lung contusion model. METHODS: Twenty-eight anesthetized pigs were studied during four hours. We induced a right lung contusion with five bolt shots (70 joules each) using a 22-caliber charge in twenty of them. Eight others pigs constituted the control group. The trauma consequences were assessed by histology, measurements of arterial oxygenation, plasma cytokines, pressure-volume mechanics, hemodynamic monitoring using the PiCCO system and a pulmonary artery catheter. The extra-vascular lung water was measured using the gravimetric method. RESULTS: Histology confirmed an isolated right lung contusion without cardiac injury. Compared to baseline values, the trauma group was characterized by a decrease in cardiac index (3.3 ± 0.8 vs 3.9 ± 1.2 l/min/m(2); P < .05) and mean arterial pressure (80 ± 21 vs 95 ± 16 mmHg; P < .05) without preload or afterload modification. Oxygenation (PaO2/FiO2: 349 ± 87 vs 440 ± 75; P < .05) and static compliance (26.3 ± 7.4 vs 30.3 ± 7.8 ml/cmH2O; P < .05) were also impaired during two hours compared to baseline. No edema was noticed in either group whatever the lung considered. All measured cytokines were below the detection threshold. CONCLUSIONS: An isolated right lung contusion is associated with rapid but transient cardiorespiratory impairments. Despite the large extent of the lung contusion, no pulmonary edema appeared during the period studied.

Short-term effects of low-volume resuscitation with hypertonic saline and hydroxyethylstarch in an experimental model of lung contusion and haemorrhagic shock.

OBJECTIVES: This study aimed to assess the short-term respiratory tolerance and haemodynamic efficiency of low-volume resuscitation with hypertonic saline and hydroxyethylstarch (HS/HES) in a pig model of lung contusion and controlled haemorrhagic shock. We hypothesised that a low-volume of HS/HES after haemorrhagic shock did not impact contused lungs in terms of extravascular lung water 3hours after trauma. METHODS: A lung contusion resulting from blunt chest trauma was induced in 28 anaesthetised female pigs with five bolt-shots to the right thoracic cage, followed by haemorrhagic shock and fluid resuscitation. Pigs were randomly allocated into two groups: fluid resuscitation by 4ml/kg of HS/HES, or fluid resuscitation by 10ml/kg of normal saline (NS). Monitoring was based on transpulmonary thermodilution and a pulmonary artery catheter. After 3h, animals were euthanized to measure extravascular lung water (EVLW) by gravimetry. RESULTS: Blunt chest trauma was followed by a transient collapse and hypoxaemia in both groups. Post-mortem gravimetric assessment demonstrated a significant difference between EVLW in the NS-group (8.1±0.7ml/kg) and in the HS/HES-group (6.2±0.6ml/kg, P=0.038). Based on a pathological EVLW threshold of > 7ml/kg, results indicated that only the NS-group experienced moderate pulmonary oedema, contrary to the HS/HES-group. After haemorrhagic shock, HS/HES infusion enabled the restoration of effective mean arterial pressure and cardiac index. Intrapulmonary shunting increased transiently after fluid resuscitation but there was no significant impairment of oxygenation. CONCLUSION: In this pig model of lung contusion, the short-term assessment of fluid resuscitation after haemorrhagic shock with 4ml/kg of HS/HES showed that pulmonary oedema was avoided compared to fluid resuscitation with 10ml/kg of NS.

Efficiency and safety of a noninvasive therapeutic hypothermia protocol in cardiac arrest.

OBJECTIVES: Therapeutic hypothermia (TH) is part of the treatment strategy for comatose survivors of cardiac arrest (CA). The aim of our study was to evaluate the efficiency and the safety of a noninvasive and affordable cooling procedure applied to all types of CA in an ICU. STUDY DESIGN: This was a retrospective, observational, monocenter study. PATIENTS AND METHODS: In all patients remaining unconscious after CA, irrespective of their initial cardiac rhythm, TH was induced with a rapid intravenous infusion of 30 ml/kg ice-cold (4°C) saline fluid associated with external surface cooling involving ice packs and wet sheets. The body temperature was maintained between 32 and 34°C during 24 h using external surface cooling only. The patients were then passively rewarmed. RESULTS: Of 200 eligible patients, 145 were treated by TH; 104 patients completed the 24-h TH treatment. The primary cause of noninclusion or secondary exclusion was severe hemodynamic impairment. From induction, the median time to reach the target temperature was 167 min (47-300 min). During the protocol, 24 patients did not remain within the targeted temperature range. Adverse events included hypokalemia (44%), severe arrhythmia (13.8%), bleeding (4.8%), and seizure (1.4%). All patients presented hyperglycemia. The oxygen partial pressure to oxygen fractional concentration (PaO2/FiO2) ratio remained constant after initiation and throughout the procedure, even in patients with poor systolic function. CONCLUSION: This noninvasive TH procedure seems efficient and safe in all patients remaining comatose after CA. Thanks to its simplicity, it could allow prehospital cooling to reach the target temperature more rapidly.

Diagnostic yield and safety of CT scans in ICU.

PURPOSE: Critically ill patients often require CT scans. Adverse events (AE) can occur during intra-hospital transport (IHT). The aim of this prospective study was to determine the diagnostic and therapeutic yield and the safety of CT scans in ICU patients. METHODS: All ICU patients having a CT scan for diagnostic purposes were eligible. Diagnostic yield was evaluated by the agreement (full, partial or disagreement) between the physician main diagnostic hypothesis before the CT scan and the diagnosis established after the CT scan. Therapeutic yield was assessed by therapeutic changes after the CT scan. The safety was determined by the AE rate during IHT. RESULTS: A total of 533 CT scans were performed on 359 patients in three teaching hospital ICUs. The diagnostic yield of CT scan showed 40.7 % of full agreement, 5.6 % of partial agreement and 53.7 % of disagreement with the main diagnostic hypothesis formulated before the CT scan. The CT-scan brought new elements to the diagnosis in 22.9 % of the cases. There was 54.4 % of therapeutic change after CT scan, while 22.3 % of AE occurred during IHT, including 6.7 % of life-threatening events. AE occurred more frequently in the first 48 h after ICU admission, in the most severely ill patients (higher SAPS II at admission), and when there was a large amount of equipment required for transport. CONCLUSIONS: The CT scan as a diagnostic procedure invalidated a diagnostic hypothesis and led to a therapeutic change in more than half of the cases.

Effectiveness of SAPS III to predict hospital mortality for post-cardiac arrest patients.

PURPOSE: The mortality for patients admitted to intensive care unit (ICU) after cardiac arrest (CA) remains high despite advances in resuscitation and post-resuscitation care. The Simplified Acute Physiology Score (SAPS) III is the only score that can predict hospital mortality within an hour of admission to ICU. The objective was to evaluate the performance of SAPS III to predict mortality for post-CA patients. METHODS: This retrospective single-center observational study included all patients admitted to ICU after CA between August 2010 and March 2013. The calibration (standardized mortality ratio [SMR]) and the discrimination of SAPS III (area under the curve [AUC] for receiver operating characteristic [ROC]) were measured. Univariate logistic regression tested the relationship between death and scores for SAPS III, SAPS II, Sequential Organ Failure Assessment (SOFA) Score and Out-of-Hospital Cardiac Arrests (OHCA) score. Independent factors associated with mortality were determined. RESULTS: One-hundred twenty-four patients including 97 out-of-hospital CA were included. In-hospital mortality was 69%. The SAPS III was unable to predict mortality (SMRSAPS III: 1.26) and was less discriminating than other scores (AUCSAPSIII: 0.62 [0.51, 0.73] vs. AUCSAPSII: 0.75 [0.66, 0.84], AUCSOFA: 0.72 [0.63, 0.81], AUCOHCA: 0.84 [0.77, 0.91]). An early return of spontaneous circulation, early resuscitation care and initial ventricular arrhythmia were associated with a better prognosis. CONCLUSIONS: The SAPS III did not predict mortality in patients admitted to ICU after CA. The amount of time before specialized CPR, the low-flow interval and the absence of an initial ventricular arrhythmia appeared to be independently associated with mortality and these factors should be used to predict mortality for these patients.

Midterm effects of fluid resuscitation strategies in an experimental model of lung contusion and hemorrhagic shock.

BACKGROUND: This study compared three different fluid resuscitation strategies in terms of respiratory tolerance and hemodynamic efficacy in a pig model of blunt chest trauma with lung contusion and controlled hemorrhagic shock. We hypothesized that the choice of fluid resuscitation strategy (type and amount of fluids) may impact differently contused lungs in terms of extravascular lung water (EVLW) 20 h after trauma. METHODS: Anesthetized female pigs (n = 5/group) received five bolt shots to the right thoracic cage and allowed to hemorrhage for 30 min, with 25 to 30 mL/kg of blood loss. Pigs were randomly assigned to resuscitation groups that maintained a minimum mean arterial blood pressure of 70 mmHg with one of three methods: normal saline (NS), unrestricted normal saline; NOREPI, low-volume normal saline with norepinephrine; or HS-HES, hypertonic saline with hydroxyethyl starch. Control pigs were anesthetized, but received no injury or treatment. After 20 h, animals were killed to measure EVLW by gravimetry. RESULTS: Fluid loading was significantly different in each group. All three treatment groups had higher EVLW than controls. Moderate, bilateral pulmonary edema was observed in the NS and HS-HES groups. The three treatment groups showed similar reductions in oxygenation. Static pulmonary compliance was diminished in the NS and HS-HES groups, but compliance was similar in NOREPI and control groups. The NOREPI group had pathological lactate levels. CONCLUSIONS: This study demonstrated the impact of fluid resuscitation on contused lungs. Twenty hours after the trauma, all three resuscitation approaches showed modest clinical consequences, with moderate lung edema and reduced compliance in response to the infused volume.