[Rehabilitation of patients with facial nerve neuropathy in cases of increased muscle tone on the healthy side of the face]. / Reabilitatsiya patsientov s neiropatiei litsevogo nerva pri povyshenii tonusa myshts na zdorovoi storone litsa.

OBJECTIVE: To evaluate the effectiveness of physical rehabilitation (PR) and injections of botulinum toxin type A (BTA) in the correction of muscles hypertonicity ty of the healthy side of the face or its prevention in patients with facial nerve neuropathy (FNN). MATERIAL AND METHODS: One hundred and forty-six patients with FNN of various etiologies with muscles hypertonicity of the healthy side or the risk of its development were studied. The term of treatment was 33 [10; 99] days. There are 88 women and 58 men aged 42 [34; 56] years. Diagnosis included clinical examination and stimulation electroneuromyography (ENMG, n=113; 77.4%) with assessment of M-wave amplitude asymmetry. All patients were prescribed a standard PR complex, in addition - relaxation of the muscles of the healthy side by injections of BTA (Incobotulinumtoxin A) - BTA group (n=38) or by special PR techniques - physiotherapy group (n=108). RESULTS: In both groups, patients were comparable in age, sex and severity of FNN at clinical assessment. But objectively, in the BTA group there were more symptomatic forms (63.2% vs 43.5%; p=0.038), cases of M-wave amplitude asymmetry over 90% in ≥2 branches (52.6% vs 18.5%; p=0.032). Displacement of the face midline was a factor limiting recovery (68.4% and 62%; χ2=0.495; p=0.482) in two groups. With amplitude asymmetry of more than 90% in ≥2 branches (a predictor of the risk of unfavorable outcome), a favorable outcome occurred more often in the BTA group (80% versus 45%; χ2=5.227; p=0.023). In case of amplitude asymmetry of less than 90% in all branches, a favorable outcome was observed in two groups. CONCLUSION: Indications for botulinum therapy in patients with FNN are deep prosoparesis or prosoplegia, muscles hypertonicity of the healthy side, displacement of the face midline, ENMG predictors of the risk of unfavorable outcome. PR is an effective method of prevention in patients with a favorable prognosis of outcome or treatment of mild forms.

[Bilateral stenting for malignant tracheal and bronchial stenosis]. / Bilateral'noe stentirovanie opukholevogo stenoza trakhei i glavnykh bronkhov: pervyi opyt (klinicheskoe nablyudenie).

Malignant lesions of tracheal bifurcation usually lead to respiratory failure and risk of mortality. Airway stenting is the only minimally invasive method for these patients. The authors present a patient with T4N3M0 left-sided lung cancer (inoperable stage IIIc) complicated by respiratory failure due to tracheal bifurcation obstruction. Bilateral stenting by self-expanding stents with perforated coatings was effective for airway recanalization and provided subsequent chemotherapy.

[Enteral therapy in patients with blunt abdominal trauma]. / Enteral'naya terapiya u patsientov s zakrytoi travmoi zhivota (predvaritel'nye rezul'taty).

OBJECTIVE: To improve the outcomes in ICU patients with blunt abdominal trauma via enteral therapy by saline enteral solution. MATERIAL AND METHODS: A retrospective and prospective study included 24 patients (18 (75%) men and 6 (25%) women) with blunt abdominal trauma who underwent examination and treatment at the Sklifosovsky Research Institute for Emergency Care. Age of patients ranged from 38 to 81 years (mean 50.1±13.6). RESULTS: Enteral therapy was followed by normalization of serum lactate, alanine aminotransferase and aspartate aminotransferase after 3 days. There were significant differences in decrease of lactate dehydrogenase, alanine aminotransferase and C-reactive protein. In the control group, these parameters decreased only by the 10th day. CONCLUSION: Inclusion of saline enteral solution into the complex therapy contributes to earlier recovery of gastrointestinal function and prevents compartment syndrome. These aspects reduced the number of patients with multiple organ failure.

[Rehabilitation of patients with complications of facial nerve neuropathy]. / Reabilitatsiya patsientov s oslozhneniyami neiropatii litsevogo nerva.

OBJECTIVE: To compare the effectiveness of physical rehabilitation (PR) and botulinum therapy in the treatment of facial nerve neuropathy (FNN) complications. MATERIAL AND METHODS: Sixty-eight patients with FNN of various etiologies, including 70 women and 6 men aged 38 [31; 46] years, were studied. Time to seek medical help was 717 [256; 1638] days. Diagnosis of the motor pattern included determining the strength of facial muscles, identifying complications - muscle hypertonicity and synkinesis, assessment with the House-Brackmann Grading System, the Facial Nerve Grading System 2.0 and the Sunnybrook facial grading system. All patients were prescribed a standard PR complex, additionally muscle relaxation was performed on both sides by injections of Incobotulinumtoxin A (BTA) - BTA group (n=34; 44.7%) or special PR techniques - physiotherapy group (n=42; 55.3%). RESULTS: The both groups are comparable by age, sex, etiology and duration of treatment, however, patients in the BTA group have more severe stage of FNN (U=534.5; p=0.031). There is a limitation in the volume of active movements in patients with muscles hypertonicity of the affected side, which was associated with insufficient muscle strength. In the BTA group, the severity of complications (muscles hypertonicity and synkinesis) is decreased on the affected side, and in 1/4 of the cases it is accompanied by an increase of muscles strength. In the physiotherapy group, the decrease in the severity of complications is less significant, but is associated with an increase of muscles strength (χ2=45.505; p<0001). CONCLUSIONS: PR and botulinum toxin therapy are effective methods of treating FNN complications. Special PR techniques for relaxing and stretching muscles are applicable for the prevention and treatment of mild disorders. Botulinum therapy allows achieving a significant stable clinical effect in the treatment of moderate and severe complications (muscle hypertonicity and synkinesis).

[The first Russian experience of radiofrequency ablation in the treatment of adenoma of the major duodenal papilla with intraductal growth in the common bile duct]. / Pervyi v Rossii opyt primeneniya radiochastotnoi ablyatsii v lechenii adenomy bol'shogo sosochka dvenadtsatiperstnoi kishki s vnutriprotokovym rostom v kholedokh.

Adenoma of the major duodenal papilla can cause bile flow blockade and obstructive jaundice. We present successful endoscopic radiofrequency ablation for adenoma of the major duodenal papilla with intraductal growth in the common bile duct.

[Complications of percutaneous endoscopic gastrostomy in intensive care patients with dysphagia associated with neurological disorders]. / Oslozhneniya chreskozhnoi endoskopicheskoi gastrostomii u reanimatsionnykh bol'nykh s sindromom disfagii tsentral'nogo geneza.

OBJECTIVE: To develop an effective method for percutaneous endoscopic gastrostomy using gastropexy technology. MATERIAL AND METHODS: We retrospectively analyzed 260 ICU patients with dysphagia associated with neurological disorders between 2010 and 2020. All patients were divided into two groups: the main group (n=50) - percutaneous endoscopic gastrostomy with gastropexy, control group (n=210) - surgery without fixing the anterior wall of the stomach to the abdominal wall. RESULTS. G: Astropexy significantly reduced the incidence of postoperative complications (p=0.045) and severe complications (grade IIIa and higher) (χ2=3.701, p=0.055). Early postoperative complications occurred in 20 (7.7%) patients. Surgery and subsequent treatment were associated with normalization of leukocyte count (p=0.041), C-reactive protein (p=0.024) and serum albumin (p=0.0012). Mortality was similar in both groups. Overall 30-day mortality rate in both groups was 20.8% that was associated with clinical severity of patients. Percutaneous endoscopic gastrostomy was not the direct cause of death in any case. However, complications of endoscopic gastrostomy aggravated the underlying disease in 2.9% of cases. CONCLUSION: Percutaneous endoscopic gastrostomy with gastropexy reduces the incidence of postoperative complications.

[The neuropathy of marginal mandibular branch of the facial nerve]. / Izolirovannoe porazhenie kraevoi nizhnechelyustnoi vetvi litsevogo nerva.

OBJECTIVE: To analyze the diagnosis, treatment and rehabiltation of patients with marginal mandibular branch of the facial nerve (MMB). MATERIAL AND METHODS: We have collected 6 patients (mean age 40 [33.8; 44] years) with isolated lesion of MMB that innervates the depressor labii inferioris and chin muscle. The illness duration without any improvement was 35 [13; 44] days. Diagnosis and treatment were carried out according to the special algorithm developed and implemented at the N.V. Sklifosovsky Research Institute of Emergency Medicine. RESULTS: With needle myography of the muscle that lowers the lower lip, the change in the ratio of the maximum amplitudes of the interference pattern (MAIP) in all patients exceeded 15%, and in 2 cases it was more than 90%. Comparing with the healthy face side, a change of the MAIP ratio less than 90% was considered as the biomarker of favorable prognosis, with conservative treatment recommendations, e.g. the set of exercises with targeted effects on depressor labii inferioris. With regular exercises, patients noted positive dynamics of restoring the symmetry of the smile in 1-2 months of the disease, full recovery - in 4-5 months. In case of exercises rejection, there was no positive dynamics. A change in the MAIP ratio more than 90% or the absence of motor unit potentials was considered as the biomarker of an unfavorable outcome and an indication for surgical treatment. After surgical treatment, the improvement occurred within 4-5 months. In conservative treatment group, there were no positive changes even with regular exercises. CONCLUSION: The diagnosis of an isolated lesion of MMB is established clinically using a protocol of step-by-step assessment of facial muscle function, and tactics is determined by needle myography with depressor labii inferioris. Even with favorable myographic predictors, spontaneous recovery may not occur, exercises with a targeted effect on the depressor labii inferioris are required, and in the presence of unfavorable predictors, surgical treatment is reccomended.

[Long-term follow-up study of post-COVID-19 patients].

AIM: To evaluate dynamic changes in the lungs, hemostasis system, immune system in different terms after coronavirus pneumonia. MATERIALS AND METHODS: Ventilation-perfusion single-photon emission computed tomography/computed tomography (CT), functional methods of lung investigation, evaluation of hemostasis system, immune status and specific humoral immune response were performed and evaluated in different terms after coronavirus pneumonia. A total of 71 patients were examined according to this protocol. We examined patients with the lesion volume not less than 50% according to chest CT. All patients were divided into 2 groups depending on the distance from the acute stage of coronavirus pneumonia. Group 1 included patients who were examined early (3060 days after hospital discharge), group 2 included patients who were examined later (61180 days after hospital discharge). RESULTS: We obtained gradual regression of pathologically-modified tissue from 67.3% during the inpatient phase to 30.9% during the early period and to 19.7% during the late period of examination, according to CT scan of the chest organs. The same tendency was demonstrated by diffusion capacity of the lungs. Perfusion scintigraphy data showed a decrease in perfusion deficit from 26.012.8% during the early period of examination to 19.46.2% during the late period of examination. On the contrary, ventilatory scintigraphy demonstrates the increase of isotope passage time through the alveolar-capillary membrane over time (from 48.231.3 minutes in the early period to 83.637.2 minutes in the late period). An increase in D-dimer was detected in 24% of patients in the early group. The levels of inflammatory markers, indices of immune status, and specific humoral immune response did not differ in the two described groups. CONCLUSION: The results demonstrate gradual regression of pathological changes caused by coronavirus infection.

Intensive Care of Patients with COVID-19.

The severe course of COVID-19 requires treatment in emergency and intensive care units. Acute respiratory failure due to the development of pneumonia and acute respiratory distress syndrome is the most common and life-threatening manifestation of the new coronavirus infection. Treatment of patients with severe and extremely severe COVID-19; the use of modern schemes and protocols for drug therapy, mechanical ventilation, and extracorporeal membrane oxygenation; sorption techniques; the use of thermal helium; hemostasis correction; and rehabilitation problems are discussed.

[First case of thrombolysis with non-immunogenic staphylokinase in a patient with ischemic stroke receiving dabigatran etexilate followed by thrombectomy]. / Pervyi sluchai tromboliticheskoi terapii pri pomoshchi neimmunnogennoi stafilokinazy u patsientki s ishemicheskim insul'tom, poluchayushchei dabigatrana eteksilat, s posleduyushchei trombektomiei.

Currently, five oral anticoagulants have been shown to be effective in preventing recurrent ischemic stroke and/or systemic embolism in patients with non-valvular atrial fibrillation. However, 1.1-2.2% of patients taking oral anticoagulants develop ischemic strokes. The use of oral anticoagulants limits the possibility of systemic thrombolytic therapy, as this is associated with an increased risk of symptomatic hemorrhagic transformation. The exception is cases when, with the help of a specific antagonist, it is possible to neutralize the effect of the anticoagulant in the shortest possible time and achieve normocoagulation. Currently, the Russian Federation allows two drugs for systemic thrombolytic therapy in patients with ischemic stroke in the «therapeutic window¼ up to 4.5 hours from the onset of the disease - recombinant tissue plasminogen activator and non-immunogenic staphylokinase, which showed no less efficacy and safety in the FRIDA study compared to recombinant tissue plasminogen activator. This article describes a clinical case of the first systemic thrombolytic therapy with a non-immunogenic staphylokinase after the use of idarucizumab in a patient taking dabigatran etexilate, followed by thrombectomy.

[Russian multicenter observational clinical study «Register of respiratory therapy for patients with stroke (RETAS)¼: a comparative analysis of the outcomes of stroke]. / Rossiiskoe mnogotsentrovoe observatsionnoe klinicheskoe issledovanie «Registr respiratornoi terapii u patsientov s ONMK (RETAS)¼: sravnitel'naya kharakteristika iskhodov insul'ta.

OBJECTIVE: To analyze the treatment of patients with severe stroke requiring respiratory support, and identify predictors of death. MATERIAL AND METHODS: A multicenter observational clinical study «REspiratory Therapy for Acute Stroke¼ (RETAS) was conducted under the aegis of the «Federation of Anaesthesiologists and Reanimatologists¼ (FAR). The study involved 14 clinical centers and included 1289 stroke patients with respiratory support. RESULTS: We found that initial hypoxemia in the 28-day period was associated with higher mortality than in absence of hypoxemia (in patients with 20 or more NIHSS scores) (76.22% versus 63.45%, p=0.004). Risk factors for lethal outcome: hyperventilation used to relieve intracranial hypertension compared with group of patients who were not treated with hyperventilation (in patients with 20 or more NIHSS scores) (79.55% versus 72.75%, p=0.0336); volume-controlled ventilation (VC) versus pressure-controlled ventilation (PC) (in patients with 20 or more NIHSS scores) (p<0.001); use of clinical methods for monitoring ICP in comparison with instrumental ones (87.64% versus 62.33%, p<0.001). It has been proved that the absence of nutritional insufficiency in patients with stroke is associated with a higher probability of a positive outcome (GOS 4 and 5) in comparison with patients with signs of nutritional insufficiency, for the group with NIHSS less than 14 points (p<0.001). CONCLUSIONS: A group of factors associated with a deterioration in the prognosis of outcomes in patients with stroke who are undergoing ventilation has been identified: hypoxemia at the start of respiratory support, lack of instrumental monitoring of ICP, the use of hyperventilation to correct ICP, ventilation with volume control (VC), as well as the presence of nutritional insufficiency.

[Locoregional anesthesia in endoscopic surgery of intracerebral hypertensive hemangiomas]. / Lokoregionarnaya anesteziya v endoskopicheskoi khirurgii vnutrimozgovykh gipertenzivnykh gematom.

INTRODUCTION: Currently, minimally invasive methods of surgical treatment of hypertensive intracerebral hematomas (ICHs) are actively used. However, anesthetic management of these surgeries are unclear. Moreover, advisability of locoregional anesthesia (LRA) for endoscopic aspiration of hypertensive ICHs has not been studied. OBJECTIVE: To analyze application of regional anesthesia in minimally invasive surgery of hypertensive intracerebral hematomas. MATERIAL AND METHODS: Patients were divided into 2 groups. Group 1 included 45 patients who underwent surgery under total intravenous anesthesia with mechanical ventilation (TIVA + mechanical ventilation), group 2 (n=43) - surgery under LRA. The incidence of pneumonia and postoperative outcomes in accordance with the GOS grading system were analyzed depending on the method of anesthesia. RESULTS: Pneumonia was 3 times more common in the first group (33%) that required prolonged ventilation and tracheostomy. Thus, there were 9 tracheostomies (20%) in the first group. In the second group, one patient required mechanical ventilation on the second postoperative day due to severe chronic obstructive pulmonary disease followed by deterioration of respiratory failure. Tracheostomy was also performed in this case. According to analysis of GOS outcomes, the LRA group was characterized by 4 times lower mortality and 1.5 times greater number of patients with good recovery and moderate disabilities compared with the first group. CONCLUSIONS: LRA is a feasible and effective method for the anesthetic management of minimally invasive surgery in patients with hypertensive ICHs. This approach ensures decrease of mortality rate, increase of good neurological outcomes and reduce pulmonary infectious complications.

[New perspectives of motor rehabilitation of patients after focal brain lesions]. / Novye perspektivy dvigatel'noi reabilitatsii patsientov posle ochagovogo porazheniia golovnogo mozga.

Rehabilitation of patients after focal brain lesions is one of the topical issues of modern medicine. Motor disorders are known to develop in more than 80% of survivors of stroke and traumatic brain injury and be one of the main causes of disability, which necessitates an active search for new effective techniques for correction of motor disorders. Modern rehabilitation includes both traditional techniques for recovery of patients with motor deficit (exercise therapy and physiotherapy) and botulinum therapy, kinesiotherapy, mechanotherapy, etc., which have been developed in recent years. Robotic technologies have been developed, improved, and implemented. Currently, due to progress in computerization, virtual reality-based rehabilitation of patients is of particular interest. The article reviews the key studies in this field. We describe various visualization methods and means of immersion in a virtual environment for recovery of upper and lower extremity function in patients with focal brain lesions. The study provides an assessment of the effectiveness and safety of various virtual reality-based rehabilitation programs in patients with motor disorders after stroke and traumatic brain injury.

[Prognostic significance of leukocyte count in the venous blood in the acute stage of cerebral aneurism rupture]. / Prognosticheskaia znachimost' kontsentratsii leikotsitov v venoznoi krovi v ostrom periode razryva tserebral'nykh anevrizm.

AIM: To determine a prognostic role of leukocyte count in the venous blood in the acute stage of cerebral aneurysm (CA) rupture. MATERIAL AND METHODS: Fifty-one patients with CA rupture, aged from 20 to 65 years, hospitalized in the first 72 h over the period from 01.10.12 to 01.02.16 were examined. The severity of disease and anatomical form of hemorrhage was corresponded to III-IV degree on the W. Hunt - R. Hess scale and Fisher scale. All patients underwent surgery. Outcomes after open and endovascular surgeries were similar. RESULTS: Normal leukocyte number in the venous blood at admission was identified in 12 (24%) of patients (on average 7.3±1.4·109/L), leukocytosis in 39 (76%) (14.3±3.1·109/L) (p<0.0001). Leukocyte number in the acute stage of CA rupture was correlated with the frequency and severity of the vessel spasm. In 28 (55%) of patients with ischemic lesions of the brain matter, mean leukocyte number in the first 72 h after hemorrhage was higher by 2-24% (3±4.8·109/L) compared to patients without ischemia (11.9±2.5·109/L) (p=0.06). The level of leukocytes in survivors was lower by 3 - 28% (122±3.4·109/L) compared to patients with fatal outcome and patients with severe neurological deficit after the surgery (14.5±3.9·109/L) (p>0.05). CONCLUSION: The increase in leukocyte number in the venous blood in the first 72 h after CA rupture ≥10,1·109/L is a reliable risk factor of marked vessel spasm. The level of leukocytes in patients with cerebral ischemia and poor prognosis in the first 72h after aneurysmal hemorrhage was higher by 2-28% compared to survivors without neurological impairment or mild neurological deficit.

[Dilated cardiomyopathy as a cause of ischemic stroke]. / Dilatatsionnaya kardiomiopatiya kak prichina ishemicheskogo insul'ta.

Dilated cardiomyopathy (DCMP) is a disease of the myocardium characterized by the dilatation of heart cavities with the development of systolic dysfunction but without a decrease in the thickness of the myocardium. DCMP is a frequent cause of cardioembolic syndrome, in particular cardioembolic ischemic stroke (CES). A case of a patient with DCMP after CES is presented.

[POSITIVE END-EXPIRATORY PRESSURE (PEEP) INFLUENCES ON INTRACRANIAL PRESSURE, SYSTEMIC HEMODYNAMICS AND PULMONARY GAS EXCHANGE IN PATIENTS WITH INTRACRANIAl HEMORRHAGE IN CRITICAL STATE].

Positive end-expiratory pressure is one of the main parameters of respiratory support influencing the gas exchange. However, despite the number ofpositive effects, PEEP can compromise venous outflow from the cranial cavity, increased intracranial pressure, decreased venous return and cardiac output and, consequently, reduced blood pressure and cerebral perfusion. The article presents the results of a survey of 39 patients with intracranial hemorrhage in critical state, undergoing respiratory support with different levels of positive end-expiratory pressure. Increasing of PEEP to 15 cm H2O had no adverse effect on mean arterial pressure, heart rate and cerebral perfusion pressure and led only to an clinical insignificant increase (maximum on 2.4 +/- 5.1 mmHg) in intracranial pressure. The greatest hemodynamic changes were observed with increasing PEEP up to 20 cm H2O in patients with preserved compliance ofthe respiratory system. The instability of cerebral perfusion and intracranial pressure associated with a decrease in cardiac output and preload and the exhaustion of compensatory mechanism of peripheral vascular resistance. High levels of PEEP despite the trend towards Cstat reduction will not lead to an increase in the content of extravascular lung water Thus a gradual increase of PEEP to 15 cm H2O can be safe and effective method of improving pulmonary gas exchange in patients with intracranial hemorrhage in critical state.

[Guidelines for the management of severe traumatic brain injury. Part 3. Surgical management of severe traumatic brain injury (Options)].

Traumatic brain injury (TBI) is one of the main causes of mortality and severe disability in young and middle age patients. Patients with severe TBI, who are in coma, are of particular concern. Adequate diagnosis of primary brain injuries and timely prevention and treatment of secondary injury mechanisms markedly affect the possibility of reducing mortality and severe disability. The present guidelines are based on the authors' experience in developing international and national recommendations for the diagnosis and treatment of mild TBI, penetrating gunshot wounds of the skull and brain, severe TBI, and severe consequences of brain injury, including a vegetative state. In addition, we used the materials of international and national guidelines for the diagnosis, intensive care, and surgical treatment of severe TBI, which were published in recent years. The proposed recommendations for surgical treatment of severe TBI in adults are addressed primarily to neurosurgeons, neurologists, neuroradiologists, anesthesiologists, and intensivists who are routinely involved in treating these patients.

[Guidelines for the diagnosis and treatment of severe traumatic brain injury. Part 2. Intensive care and neuromonitoring].

Traumatic brain injury (TBI) is one of the major causes of death and disability in young and middle-aged people. The most problematic group is comprised of patients with severe TBI who are in a coma. The adequate diagnosis of primary brain injuries and timely prevention and treatment of the secondary injury mechanisms largely define the possibility of reducing mortality and severe disabling consequences. When developing these guidelines, we used our experience in the development of international and national recommendations for the diagnosis and treatment of mild traumatic brain injury, penetrating gunshot wounds to the skull and brain, severe traumatic brain injury, and severe consequences of brain injuries, including a vegetative state. In addition, we used international and national guidelines for the diagnosis, intensive care, and surgical treatment of severe traumatic brain injury, which had been published in recent years. The proposed guidelines concern intensive care of severe TBI in adults and are particularly intended for neurosurgeons, neurologists, neuroradiologists, anesthesiologists, and intensivists who are routinely involved in the treatment of these patients.

[AQUATIC AND ELECTROLYTE DISORDERS AT THE PATIENT WITH SEVERE TRAUMATIC BRAIN INJURY.]

This article is dedicated to the problem ofwater and electrolyte disturbances in patient with acute severe head trauma. We present the case study of patient with severe head injury who consistently developed diabetes insipidus and cerebral salt wasting syndrome. His water and electrolyte disorders were successfully corrected by target-oriented intensive care. Constant tight monitoring and of intensive care allowed to avoid secondary ischemic injuries till the water and electrolytic homeostasis regulation mechanisms restoration.

[CORRECTION OF HEMOSTASIS DISORDER IN HEMORRHAGIC SHOCK].

It is a clinical case of successful correction of hemostasis disorder in hemorrhagic shock. This case demonstrates the need to perform advanced tests that assess hemostatic system in patients with ongoing bleeding. Using of thromboelastography helped us to make a comprehensive assessment of hemostatic system that allowed to detect the point of application of drugs and substitution therapy. Coagulation disorder was treated by intravenous injection of Ca2+. In this case the cause of hypocalcemia was combination offactors such as electrolytes losing during massive bleeding and progressing metabolic acidosis. Therefore, monitoring the level of ionized calcium is especially important in patients undergoing massive blood loss and receiving large doses of donor blood components.