A simple and novel equation to estimate the degree of bleeding in haemorrhagic shock: mathematical derivation and preliminary in vivo validation

Determining blood loss [100% – RBV (%)] is challenging in the management of haemorrhagic shock. We derived an equation estimating RBV (%) via serial haematocrits (Hct1 , Hct2 ) by fixing infused crystalloid fluid volume (N) as [0.015 × body weight (g)]. Then, we validated it in vivo. Mathematically, the following estimation equation was derived: RBV (%) = 24k / [(Hct1 / Hct2 ) – 1]. For validation, nonongoing haemorrhagic shock was induced in Sprague–Dawley rats by withdrawing 20.0%–60.0% of their total blood volume (TBV) in 5.0% intervals (n = 9). Hct1 was checked after 10 min and normal saline N cc was infused over 10 min. Hct 2 was checked five minutes later. We applied a linear equation to explain RBV (%) with 1 / [(Hct1 / Hct2 ) – 1]. Seven rats losing 30.0%–60.0% of their TBV suffered shock persistently. For them, RBV (%) was updated as 5.67 / [(Hct1 / Hct2 ) – 1] + 32.8 (95% confidence interval [CI] of the slope: 3.14–8.21, p = 0.002, R2 = 0.87). On a Bland-Altman plot, the difference between the estimated and actual RBV was 0.00 ± 4.03%; the 95% CIs of the limits of agreements were included within the pre-determined criterion of validation (< 20%). For rats suffering from persistent, non-ongoing haemorrhagic shock, we derived and validated a simple equation estimating RBV (%). This enables the calculation of blood loss via information on serial haematocrits under a fixed N.Clinical validation is required before utilisation for emergency care of haemorrhagic shock.

Right cardiac border to cardiac diameter (RB:CD) ratio, a simple radiological index associated with a good neurological outcome

Objective@#The optimum chest compression point during cardiopulmonary resuscitation (CPR) associated with a good neurological outcome is unestablished. We aimed to suggest the association between the point and a simple index measured on anteroposterior chest radiography (chest_AP). @*Methods@#This retrospective, cross-sectional study included all adults with available chest_AP who arrived at a university hospital from January 2014 to June 2019 for non-traumatic out-of-hospital cardiac arrest (OHCA). Distances from the vertical midsternum to the farthest right and left cardiac borders were defined as RB and LB, respectively. Their sum provided cardiac diameter (CD). Assuming the universality of cardiac anatomy, the cardiac structure immediately beneath the midsternum was compressed most forcefully during CPR. The influencing outcome of CPR was determined using the RB:CD ratio. We investigated the association of RB:CD ratio with a good neurological outcome at discharge using multiple logistic regression analysis, adjusting for the core Utstein elements and comorbidities. @*Results@#Among 429 patients (63.2±14.5 years; 121 [28.2%] female), return of spontaneous circulation, survival-to-discharge and good neurological outcome at discharge were achieved in 259 (60.4%), 121 (28.2%) and 84 (19.6%) cases, respectively. The RB:CD ratio (0.279±0.072) was divided into semi-tertiles to enhance clinical usage: 0.30 (n=161). The second group was associated with good neurological outcome (odds ratio, 6.00 [95% confidence interval, 1.58-22.8], P=0.010). @*Conclusion@#An RB:CD ratio of 0.25-0.30 measured on chest_AP is associated with good neurological outcomes in OHCA victims receiving CPR.

Determination of the theoretical personalized optimum chest compression point using anteroposterior chest radiography

OBJECTIVE: There is a traditional assumption that to maximize stroke volume, the point beneath which the left ventricle (LV) is at its maximum diameter (P_max.LV) should be compressed. Thus, we aimed to derive and validate rules to estimate P_max.LV using anteroposterior chest radiography (chest_AP), which is performed for critically ill patients urgently needing determination of their personalized P_max.LV.METHODS: A retrospective, cross-sectional study was performed with non-cardiac arrest adults who underwent chest_AP within 1 hour of computed tomography (derivation:validation=3:2). On chest_AP, we defined cardiac diameter (CD), distance from right cardiac border to midline (RB), and cardiac height (CH) from the carina to the uppermost point of left hemi-diaphragm. Setting point zero (0, 0) at the midpoint of the xiphisternal joint and designating leftward and upward directions as positive on x- and y-axes, we located P_max.LV (x_max.LV, y_max.LV). The coefficients of the following mathematically inferred rules were sought: x_max.LV=α₀*CD-RB; y_max.LV=β₀*CH+γ₀ (α₀: mean of [x_max.LV+RB]/CD; β₀, γ₀: representative coefficient and constant of linear regression model, respectively).RESULTS: Among 360 cases (52.0±18.3 years, 102 females), we derived: x_max.LV=0.643*CD-RB and y_max.LV=55-0.390*CH. This estimated P_max.LV (19±11 mm) was as close as the averaged P_max.LV (19±11 mm, P=0.13) and closer than the three equidistant points representing the current guidelines (67±13, 56±10, and 77±17 mm; all P<0.001) to the reference identified on computed tomography. Thus, our findings were validated.CONCLUSION: Personalized P_max.LV can be estimated using chest_AP. Further studies with actual cardiac arrest victims are needed to verify the safety and effectiveness of the rule.

Search for Structural Cardiac Abnormalities Following Sudden Cardiac Arrest Using Post-mortem Echocardiography in the Emergency Department: A Preliminary Study

PURPOSE: Sudden cardiac arrest (SCA) accounts for approximately 15% of all-cause mortality in the US and 50% of all cardiovascular mortalities in developed countries; 10% of cases have an underlying structural cardiac abnormality. An echocardiography has widely been used to evaluate cardiac abnormality, but it needs to be performed by emergency physicians available in the emergency department immediately after death, rather than by cardiologists. We aimed to determine whether post-mortem echocardiography (PME) performed in the emergency department may reveal such abnormalities. METHODS: We evaluated the reliability and validity of PME performed by emergency physicians in the emergency department. Measurement by a cardiologist was used as reference. RESULTS: Two emergency physicians performed PME on 3 out of the 4 included patients who died after unsuccessful cardiopulmonary resuscitation. PME was started within 10 minutes of death, and it took 10 minutes to complete. Parasternal views in either supine or left decubitus position were most helpful. The adequacy of the image was rated good to fair, and that of measurements was acceptable to borderline. Regarding the chamber size and left ventricular wall thickness, intraclass correlation coefficients for reliability and validity were 0.97 (n=15) and 0.95 (n=35), respectively (p<0.001). Evaluation of presence/absence of left ventricular wall thinning, valve calcification, and pericardial effusion was incomplete (3/7-5/7), precluding further analysis. CONCLUSION: Emergency physicians could perform reliable and valid PME to assess the chamber size and left ventricular wall thickness. A large prospective study with collaboration between emergency physicians and cardiologists would reveal the feasibility and usefulness of PME in diagnosing structural causes of sudden cardiac arrest.

Should We Convert Prehospital Supraglottic Airway to Endotracheal Tube Immediately in Out-of-Hospital Cardiac Arrest? A Preliminary, Retrospective, Observational Study

PURPOSE: This study examined whether the immediate conversion of the prehospital supraglottic airway (SGA) to endotracheal intubation (ETI) is associated with the return of spontaneous circulation (ROSC) and survival to discharge among out-of-hospital cardiac arrest (OHCA) victims. METHODS: This retrospective observational study included OHCA victims aged ≥18 years who were treated from 2014 to 2016. The patient-, prehospital arrest-, and emergency department (ED)-related variables were collected based on the Utstein template. The immediate conversion of SGA to ETI was defined when it had been initiated within ≤2 minutes after arrival at the ED. To investigate the factors related to ROSC and survival to discharge, multiple logistic regression analysis of the immediate conversion of SGA to ETI and variables showing a difference (p < 0.15) on the Mann-Whitney U and chi-square test was performed. RESULTS: A total of 129 patients were enrolled, with a median age of 59 years (interquartile range, 51 to 72 years). Of these, 30 (23.3%) were female, 41 (31.8%) achieved ROSC, and 7 (5.4%) survived to discharge. Sixty-nine (53.5%) received immediate conversion showing no differences in the demographic and clinical characteristics compared to the delayed conversion group. Multiple logistic regression analysis showed that ROSC was related to the existence of lung disease, presence of witnesses, and a cardiopulmonary resuscitation duration ≤15 minutes at the ED, whereas the survival to discharge was associated with the prehospital shockable initial rhythm. Neither ROSC nor survival to discharge were related to the immediate conversion of SGA to ETI. CONCLUSION: The immediate conversion of prehospital SGA to ETI at ED in an OHCA victim might be unrelated to ROSC and survival to discharge.

Calculation of the Residual Blood Volume after Acute, Non-Ongoing Hemorrhage Using Serial Hematocrit Measurements and the Volume of Isotonic Fluid Infused: Theoretical Hypothesis Generating Study

Fluid resuscitation, hemostasis, and transfusion is essential in care of hemorrhagic shock. Although estimation of the residual blood volume is crucial, the standard measuring methods are impractical or unsafe. Vital signs, central venous or pulmonary artery pressures are inaccurate. We hypothesized that the residual blood volume for acute, non-ongoing hemorrhage was calculable using serial hematocrit measurements and the volume of isotonic solution infused. Blood volume is the sum of volumes of red blood cells and plasma. For acute, non-ongoing hemorrhage, red blood cell volume would not change. A certain portion of the isotonic fluid would increase plasma volume. Mathematically, we suggest that the residual blood volume after acute, non-ongoing hemorrhage might be calculated as 0·25N/[(Hct1/Hct2)-1], where Hct1 and Hct2 are the initial and subsequent hematocrits, respectively, and N is the volume of isotonic solution infused. In vivo validation and modification is needed before clinical application of this model.

Mathematical Explanation for the Wide and Deviated Range of Optimal Hematocrit

Hematocrit is an important determinant of oxygen delivery. Of particular interest, its target level is very wide for different kinds of shock: from 30% for hemorrhagic or septic shock to 56% for secondary polycythemia. This range is not only wide but also deviated to the higher level from the optimal value of 40%. In this letter, the authors determine the mathematical basis of the wide and deviated range of hematocrit starting from the Hagen-Poisseuille equation.

A Case of Prolonged Coagulopathy in a Patient Intoxicated with Superwarfarin Rodenticide

Superwarfarin, such as brodifacoum, is a highly lethal vitamin K antagonist used as a rodenticide. Brodifacoum has a particularly long half-life in the body, which ranges to several months, and therefore requires prolonged treatment with antidotal vitamin K. We experienced a case whereby an 18-year-old male was presented to the hospital with a severe bleeding disorder. It was discovered that he had ingested brodifacoum rodenticide with intent to commit suicide. Despite continual treatment with vitamin K, the bleeding disorder persisted for several months before he recovered. We report this case with literature review.

Calculation of the Cardiothoracic Ratio from Portable Anteroposterior Chest Radiography

Cardiothoracic ratio (CTR), the ratio of cardiac diameter (CD) to thoracic diameter (TD), is a useful screening method to detect cardiomegaly, but is reliable only on posteroanterior chest radiography (chest PA). We performed this cross-sectional 3-phase study to establish reliable CTR from anteroposterior chest radiography (chest AP). First, CDChest PA/CDChest AP ratios were determined at different radiation distances by manipulating chest computed tomography to simulate chest PA and AP. CDChest PA was inferred from multiplying CDChest AP by this ratio. Incorporating this CD and substituting the most recent TDChest PA, we calculated the 'corrected' CTR and compared it with the conventional one in patients who took both the chest radiographies. Finally, its validity was investigated among the critically ill patients who performed portable chest AP. CDChest PA/CDChest AP ratio was {0.00099 x (radiation distance [cm])} + 0.79 (n = 61, r = 1.00, P < 0.001). The corrected CTR was highly correlated with the conventional one (n = 34, difference: 0.00016 +/- 0.029; r = 0.92, P < 0.001). It was higher in congestive than non-congestive patients (0.53 +/- 0.085; n = 38 vs 0.49 +/- 0.061; n = 46, P = 0.006). Its sensitivity and specificity was 61% and 54%. In summary, reliable CTR can be calculated from chest AP with an available previous chest PA. This might help physicians detect congestive cardiomegaly for patients undergoing portable chest AP.

Do Clinical Manifestations Influence the Efficiency of Computed Tomography and Ultrasonography in Diagnosing Acute Appendicitis?

PURPOSE: Radiological readings of possible or suspicious appendicitis are often unhelpful for clinicians, and normal readings may be misleading if the patient has appendicitis. We conducted a retrospective study to determine whether the efficiency of computed tomography (CT) or ultrasonography (USG) in diagnosing acute appendicitis is altered by clinical manifestations. METHODS: Data were collected from all the pathologicallyproven acute appendicitis patients who underwent CT or USG and subsequently had appendectomy between January 2009 and March 2010 at Kangwon National University Hospital. We classified radiological findings of "compatible with" and "probable" appendicitis as "highly efficient" and "possible" or "suspicious" appendicitis and "normal appendix" as "less efficient." The following clinical manifestations were included: duration of the chief complaint prior to performing CT or USG, right lower quadrant pain, pain migration, body temperature, abdominal tenderness, rebound tenderness, muscle guarding, wall rigidity, white blood cell count, percentage of polymorphonuclear cells, and C-reactive protein level. RESULTS: A total of 202 patients underwent appendectomies after imaging studies (37.2+/-20.3-years-of-age; male-to-female ratio, 1.08). Of these, 154(76.2%) received CT, 44 (21.8%) received USG, and four (2.0%) received magnetic resonance imaging. Radiological findings were highly efficient in 155 cases (76.7%) but less efficient in 47 cases (23.3%). Multiple logistic regression analysis demonstrated that the absence of pain migration was related to less efficient results (adjusted odds ratio, 3.26; 95% confidence interval, 1.16-9.12). CONCLUSION: The 'efficient' sensitivity of CT or USG in diagnosing acute appendicitis is low in the absence of a history of pain migration.

Penetrating Atherosclerotic Ulcer: Another Differential Diagnosis of Widened Mediastinum

A widened mediastinum is not always caused by aortic dissection, which is the default diagnosis among emergency physicians. Other acute aortic syndromes should be included in differential diagnosis, such as penetrating atherosclerotic ulcer (PAU), intraluminal hematoma, aneurismal leak, and traumatic transection. When an ulcerative lesion is found in the atherosclerotic aorta, especially the descending aorta of an elderly, PAU should be considered as the possible cause of widened mediastinum. We present a case of PAU, the diagnosis of which was delayed without the knowledge of PAU even though thoracic computed tomography showed widened mediastinum and suspious pericardial effusion.

Three Reinfection Cases of the Pandemic Influenza (H1N1 2009) / 감염과화학요법

Infection with influenza virus results in acquisition of immunity, preventing reinfection with the homologous virus. Although reinfection following primary infection is rare, its incidence depends on immunity of human body, antigenic diversity of influenza virus, and the presence of outbreak in the community. During the pandemic influenza (H1N1 2009), a child and two women were reinfected by H1N1 influenza virus several weeks after the primary infection, and they were successfully treated again by oseltamivir. This case series will provide additional information on diagnosis, treatment, and prevention of the pandemic influenza (H1N1 2009).

Early Extracorporeal Membrane Oxygenation in a Patient with Pandemic Influenza (H1N1 2009) and Acute Respiratory Distress Syndrome / 감염과화학요법

Despite advanced technologies in intensive care, pandemic influenza (H1N1 2009) can rapidly progress to acute respiratory distress syndrome (ARDS) and cause death in a small subset of patients. Extracorporeal membrane oxygenation (ECMO) is expected to provide adequate gas exchange, to reduce ventilator-induced lung injury and, eventually, to improve outcome in these patients. A previously healthy, young female received mechanically ventilatory support because of rapidly progressive respiratory failure caused by 2009 H1N1 influenza. As she failed to respond to high ventilatory support, ECMO was instituted at 6 hours after admission. We describe detailed course of case and literature review on ECMO, helping physicians make a decision to initiate ECMO in patients with influenza-related ARDS.