Study On Rapid Assessment Of Severe Trauma Patients With Sonography

【Background】Trauma is a common problem faced in the world.The world Health Organization reported there were 5 millions deaths due to injury in 2000,accounting for 9%of total deaths in the world.According to the report on prevention of injury in China issued by Chinese Health Ministry in 2007,injury causes 500～700 thousands deaths annually in China,which accounts for 9%of total deaths.Injury is the fifth leading cause of death.Trauma care especially care of severe trauma is a competitive issue to the modern medicine.As severe trauma patients are critically ill and in complicated conditions,the key in treating them is clinicians can make rapid and accurate assessment,then take right measures.Physical examination is a basic means,but often with limited and sometimes even wrong information from the critical illness.Bedside radiography is widely used and is limited in detecting internal organs and soft tissue disease.CT is regarded as the gold standard to diagnose most organs and plays a key role in systemic assessment of severe trauma patients.But there are potential risks to transport critically illness to CT room.For both radiography and CT,patients have to risk X-ray exposure and it's usually time-wasting and difficult to perform repeated examinations within short intervals.A simple,convenient,safe,effective and easy to repeat assessing technique is warranted in caring severe trauma.Sonography has been widely used in the hospitals due to prominent technical improvement since the 1980's.It has advantages of real-time imaging,radiation-free and non-invasive,playing an important role in treating patients.It's especially valuable for critical illness with introduction of bedside sonography.Safe and validity is required for sonography in trauma care,and much more emphasis is put on speed and convenience,which could be realized when it is performed by clinicians instead of radiologist.The concept of FAST(focused assessment with sonography for trauma) was introduced since the end of 1980's.Surgeons perform rapid sonography to detect medium and massive free intraperitoneal fluid when trauma patients arrive to the emergency room,then decide if an emergency laparotomy is warranted.FAST has greatly shortened the interval before emergency operation for trauma patients with massive intra-abdominal hemorrhage and obviously improved the outcome.Up to now,FAST has been widely used as the primary means to evaluate abdomen injury in European and American countries.It is also extended to detect pleural and peri-cardiac effusion in trauma patients.The traditional application of sonography in trauma patients is still limited.It will be more valuable if sonography could be extended for systemic assessment in trauma care.Impairment of respiratory and circulatory function is prevalent for severe trauma patients both in emergency room and in intensive care unit.Pneumothorax,pleural effusion/haemothorax,lung contusion,atelectasis are the common cause of hypoxia. To determine blood volume is also a problem often met by clinicians.It's warranted to determine whether sonography could differentiate these factors.In China,it's widely regarded that sonography should be performed by ultrasound physicians.Bedside sonography for critical illness can't be performed in many Chinese hospitals,or is limited only in daytime.In fact,it is even much difficult to guarantee that bedside sonography should reach every critical illness in time whenever it is needed.Up to now,there is no study on systemic assessment of trauma patients by clinician-performed sonography in China.【Objective】Based on the study of FAST in trauma assessment,the objective of this article is to explore and evaluate methods to assess the impairment of respiratory and circulatory function by clinician-performed sonography in severe trauma patients, thus to improve the level of treatment.【Methods and results】This is a prospective observing study conducted in a grade A,university-affiliated hospital.Severe trauma patients treated in the emergency room and emergency intensive care unit(EICU)were enrolled to this study.The inclusion criteria for patients were defines as:1)18 years or older;2)with an injury severity score(ISS)of 16 or higher.The exclusion criteria were:1)patients on cardiopulmonary resuscitation or nearly death;2)sonography could not be fully completed;3) controlled exam could not be performed or the interval between sonography and the control exam exceeded a definite time.This study were to explore and evaluate methods to assess the impairment of respiratory and circulatory function by clinician-performed sonography in severe trauma patients,including four separated parts:1)bedside sonography to diagnose and quantify pneumothorax in severe trauma patients and its clinical significance;2)the efficacy of bedside sonography in diagnosing pulmonary atelectasis/consolidation and its clinical value;3)new method by bedside sonography to precisely quantify pleural effusion/haematothorax in severe trauma patients;4)bedside sonography to determine the size of internal jugular vein and the respiratory variation index to evaluate blood volume.Sonography were performed by three fixed clinicians,using a ALOKA SSD-900 ultrasonic machine or a SonoSite MicroMaxx portable device.Data were analyzed by SPSS 13.0 and Sigmastat 2.03 statistical software.A P-value less than 0.05 was considered statistically significant.1.Subgroup on pneumothorax135 severe trauma patients were involved in this study from Oct 2004 to Dec 2005,114 male and 21 female,with an average age of 45±15 and ISS of 29.1±12.4. Pneumothorax was diagnosed by sonography according to both disappearance of lung-sliding and comet-tail,then size of pneumothorax was also determined.Bedside sonography,radiography and CT were performed within 3 hours.An emergency pleural drainage was conducted in case of critical conditions.The results of CT or pleural drainage were regarded as "golden standard".The efficacy of sonography were compare with this of radiography.Results showed there were 29 pneumothoraces in135 patients,and 25 of them were diagnosed by sonography,8 by radiography.The sensitivity,specificity,positive predictive value,negative predictive value,false positive rate,false negative rate, accuracy for both methods were 86.2%vs 27.6%(P＜0.001),97.2%vs 100% (P＞0.05),89.3%vs 100%(P＞0.05),96.3%vs 83.5%(P＜0.01),2.8%vs(P＞0.05), 13.8%vs 72.4%(P＜0.001),94.8%vs 84.4%(P＜0.01).Sonography had good consistency with CT(Kappa coefficient=0.844,P＜0.001),while radiography with poor one(Kappa coefficient=0.374,P＜0.001).In quantifying pneumothorax, sonography also showed good consistency with t CT(Kappa coefficient=0.669, P＜0.001).Diagnosis time for sonography was(2.3±2.9)min,significantly shorter than these of radiography[(19.9±10.3)min]and CT[(16.3±7.8)min].2.Subgroup on pulmonary atelectasis81 sever trauma patients in EICU were enrolled from Oct 2005 to Feb 2008,66 male and 15 female,with an average age of 47±17 and ISS of 39.1±15.6.The interval between CT and sonography was less than 10 min.Massive atelectasis and part atelectasis were divided by the extent of atelectasis.Completed and in-completed atelectasis were also determined depending on whether the consolidated lung could recruit during respiratory cycle.Both lungs were divided into two regions,upper and lower ones.Results of sonography and CT were compared in the 4 regions.The examining time and complication for both methods were also compared.The result was recorded for these treatments guided by sonography to recruit the atelectatic lung.Results showed that among the 324 lung regions of the 81 patients,154 regions were diagnosed as atelectasis by CT,and sonography diagnosed 126 regions.The total sensitivity,specificity,positive predictive value,negative predictive value, accuracy for sonography was 81.8%,100%,100%,85.9%and 91.4%.The results of sonography correlated well with those of CT(Kappa coefficient=0.825,P＜0.001), and a more close correlation was found in the lower region than in the upper one (Kappa coefficient was 0.816,0.694 respectively).The examining time and complication for sonography were much less than those of CT.Sonography could display the dynamic change of atelectasis during respiratory cycle,and continuously monitor the effect of treatment.39 regions with in-completed atelectasis got instant recruitment.Of those 87 regions with completed atelectasis/consolidation,21 regions recruited within 1 hour,28 within 1 day and 13 within 3 days,while 25 regions failed even after 3 days.3.Subgroup on pleural effusionFrom Jun 2006 to Feb 2008,46 sever trauma patients in EICU were involved in this study,and male 34,female 12,with an average age of 43±16,and average ISS of 25.4±13.9.The height of the effusion(H),the area of effusion in the middle section (S),the thickness of effusion at middle-back(T₁)and posterior axillary line(T₂)were all measured by sonography.The volume of pleural effusion(V_c)was estimated by H×S,and the actual volume of drainage(V)within 2 hours was also recorded.The correlation of actual pleural effusion(V)with fluid height(H),thickness(T₁,T₂),area (S)and the estimated volume(V_C)were analyzed to decide the most accurate indexes and methods.Results showed that actual fluid volume correlates better with S,(H and S),V_C, than with T₁,T₂ and H.The estimated volume by sonography was very close to the actual volume,especially when the actual volume was less than 500 ml.Both Logisitc gradual regression analysis and ROC curve showed only S was the most reliable to predict the actual volume exceeding 500 ml,400 ml,and 300ml among these indexes including H,S,T₁ and T₂.The corresponding threshold was 30.3 cm²,28.3 cm²,23.1 cm²,with the sensitivity and specificity of 0.77 and 0.88,0.72 and 1.0,0.95 and 1.0 respectively.4.Subgroup on the respiratory variation index of internal jugular vein to evaluate blood volumeFrom Jan 2005 to Feb 2006,50 sever trauma patients in EICU were involved in this study,and male 39,female 11,with an average age of 41±15,and average ISS of 29.7±11.5.Normal control group involved 27 people,male 19,female 8,average age was 37±13.There was no significant difference for age,sex,height,weight between the two groups.The section areas of internal jugular vein were measured at the end of inspiration and expiration by sonography(for right and left sides were recorded as RVmax and RVmin;LVmax and LVmin respectively).The respiratory variation index of internal jugular vein were calculated by(maximum section area—minimum section area)/minimum section area×100%(for right and left sides were recorded as RVrvi and LVrvi respectively).The central venous pressure(CVP)and parameters of the ventilators were also recorded.The correlation between CVP and the size,respiratory variation index of internal jugular vein were analyzed to seek a useful parameter to estimate CVP. Results showed that the section areas of the internal jugular vein were larger in severe trauma patients than in the control group.The prevalent vein was in the right side for both groups.The CVP(with patients off the ventilators)correlated well with the size,respiratory variation index of internal jugular vein in both sides.This correlation still existed for RVmin when the effect of ventilations was adjusted with a partial correlation analysis(r=0.304,p=0.04).After adjusting the influenced of airway pressure(Ppeak-Ppeep and Pplat-Ppeep),we found LVrvi correlated well with CVP(r=-0.476,-0.567,p=0.002,＜0.001 respectively),and the correlation between RVrvi and CVP disappeared(both P＞0.05).ROC analysis suggested both RVmin and LVrvi were better to estimate CVP over 12 cmH₂O,with the corresponding threshold of 1.37 cm²(sensitivity 84.6%,specificity 66.7%)and 10.8%(sensitivity 66.7%, specificity 84.6%)respectively.RVmin was significantly higher in CVP＞12 cmH₂O group than in CVP＜12 cmH₂O group and control group.LVrvi in CVP＜12 cmH₂O group was significantly higher than in CVP＞12 cmH₂O group,with the median value of 16.20%and 4.23%respectively(T=394.500,P＜0.001).【Conclusions】Results of this study showed that bedside sonography could be well used by trained clinicians to evaluate severe trauma patients,including:1)diagnose and half quantify pneumothorax quickly and exactly,which would benefit the treatment of severe trauma patients.2)quick and exact diagnosis of pulmonary atelectasis/consolidation.Sonography could also display the dynamic change of atelectasis during respiratory cycle,guiding the treatment on atelectasis and showing the instant effect.3)a precise estimation on the volume of pleural effusion/ haematothorax,makes it easy for clinicians to take measures by dynamic monitoring the volume;4)quick and effective estimation of the blood volume by measuring the size,respiratory variation index of internal jugular vein.Clinician-performed sonography is a convenient,effective and valuable means to evaluate severe trauma patients,and deserves further study and application.