PREDICTORS OF HYPOTENSION DURING SURGICAL MANAGEMENT OF FEMORAL FRACTURES IN SPINAL ANESTHESIA/PREDIKTORI HIPOTENZIJE TOKOM OPER ATIVNOG ZBRINJAVANJA PRELOMA BUTNE KOSTI U SPINALNOJ ANESTEZIJI.
ASA--American Society of Anesthesiologists
SAP--systolic arterial pressure
DAP--diastolic arterial pressure
MAP--mean arterial pressure
Hypotension is one of the most frequent adverse effects of spinal anesthesia and it may appear in up to one-third of patients undergoing surgery in spinal anesthesia . Sympathetic blockade affects the cardiovascular system by decreasing the vein inflow and systemic vascular resistance . When the level of analgesia overlaps the level of the fourth thoracic vertebra, it blocks cardioaccelerator fibers, causing pulse decrease and cardiac output reduction. Hypotension during spinal anesthesia represents a risk for brain and cardiac ischemia . The elderly patients are more inclined to get hypotension due to difficult adaptation of the cardiovascular system to the changes in circulatory system .
Patients who consume alcohol are at higher risk for hypotension, due to neuropathy which is accompanying alcoholism and causes orthostatic hypotension. Patients undergoing urgent surgery present with higher incidence of surgical hypotension than patients who undergo elective surgery .
Material and Methods
This retrospective study included 454 patients with femoral fractures who underwent surgery at the Department of Anesthesia and Reanimation of the Emergency Center of the Clinical Center of Vojvodina in the period from 2014-2016.
The research was conducted with the approval of the Ethics Committee of the Clinical Center of Vojvodina.
There is little research on predictive factors of hypotension in elderly patients with femoral fractures during surgery in spinal anesthesia.
Medical history data as well as anesthesia cards were analyzed including patient age, sex, diagnosis, type of surgical procedure, preoperative status, American Society of Anesthesiologists (ASA) classification, accompanying comorbidity (ischemic heart disease, hypertension, diabetes, chronic obstructive lung disease), and chronic therapy. Arterial pressure was preoperatively examined in each patient by an internist.
The spinal anesthesia data included the type, dose of local anesthetic, duration of anesthesia and duration of surgery. Initially, noninvasive basal arterial pressure verified the systolic and diastolic pressure prior to spinal anesthesia and then every five minutes after spinal anesthesia. The anaesthetic card included the systolic arterial pressure (SAP) and diastolic arterial pressure (DAP) in order to verify values of arterial pressure with a precision of up to 5 mmHg. Mean arterial pressure (MAP) was calculated based on the formula DAP + (SAPDAP)/3. Hypotension was defined as the drop of the arterial pressure by 20% under basal conditions.
The integral part of the data analysis was the quantity of crystalloid and colloid solutions, and vasoactive medications that were used in patients with hypotension after spinal anesthesia. Data about blood loss during surgery and the quantity of blood products that were applied in the aim of compensation (resuspended erythrocytes and freshly frozen plasma) were also analyzed.
In order to examine the connection between hypotension during surgery and medical history data, binary logistic regression was applied. The criterion variable was the value of arterial blood pressure prior to surgery, whereas the predictor variables included age, ASA, accompanying diseases, chronic therapy, diagnosis, and type of surgery.
T-test for dependent variables was applied in order to compare the last MAP at the end of surgery with the initial, preoperative MAP. Three mean pressure values were compared in the group that received bupivacaine and the group that received levobupivacaine prior to surgery, at the end of surgery, and the lowest pressure during the procedure, as well as three T-tests for independent samples.
The age of patients ranged from 20 to 93 years (mean age = 71.56; SD = 13.26; median = 74). There were more female than male patients (283; 62.3%). Detailed medical history data are presented in Table 1. The duration of surgical procedure (SP) was from 25 to 240 minutes, whereas the average duration was 67.9 minutes. During the SP, 62 patients (13.65%) received an erythrocyte transfusion, whereas the average amount of erythrocytes was 395.9 rml (SD = 56.8).
Transfusion of blood plasma was received by 4 patients (0.08%), and the average blood plasma volume was 217.5 ml (SD = 56.8).
Table 2 presents results of multivariable logistic regression analysis and the model was statistically significant (([chi square] (15) = 26.45, p < 0.05). The results suggested that the patients had higher values of MAP during the pre-operative evaluation (mean value (MV) = 103.2; SD = 14.7) in relation to the last value of MAP during surgery (MV = 84.8; SD = 13.6) and these differences were statistically significant (p < 0.001). Detailed medical history data are represented in Table 3.
The MAP measured upon surgery was by 10% (or more) lower than MAP in the pre-operative evaluation of 305 (66.4%) examined subjects, and by 20% (or more) lower in 204 (44.4%) of examined patients. The gathered results showed that the differences were present only in case of the lowest values of the mean pressure during the SP (t (425) = 2.04, p < 0.05). The group of patients who received levobupivacaine (MV= 73.99) presented with somewhat higher values of MAP in regard to the group who received bupivacaine (70.76). Detailed medical history data are represented in the Table 4.
Column N refers to the number of respondents per group. There were 337 patients in the Marcaine group, and 92 patients in the Chirocaine group.
The two last columns present Skjunis (symmetrical distribution measure) and Kurtosis (statistical measure that describes the tailedness of the probability distribution of the real valued random variable) are important characteristics for the implementation of certain statistical analyses and in all cases they were in the range of acceptable values of [+ or -] 2.00.
Examined subjects who had hypotension during surgery received a greater quantity of solution (MV= 1631.2; SD = 637.9) from those without hypotension during surgery (MV= 1344.4; SD = 489.1) and these differences were statistically significant (t(301.1) = -5.14, p < 0.001). Of the overall number of 454 patients, 122 (26.6%) received neosynephrine during the SP. The average dosage of neosynephrine was 157.7 micrograms (SD = 130.7). On average, the group of examinees who received neosynephrine was older (MV= 73.53; SD = 11.92) from the group who did not receive neosynephrine (MV = 70.83; SD = 11.12) and these differences were stastically significant (t(244.6) = -2.04, p < 0.005).
Femur fractures are most common in elderly women. The average age of the patients in this retrospective study was 71.5 years, and almost twothirds were women. The average age of the patients with fractures of the upper femur in the European literature is a bit higher, over 80 years .
During spinal anesthesia, hypotension occurs due to the blockage of sympathetic fibers. Vasodilation of the post-arterioles decreases the circulatory volume and the venous inflow into the heart. Dagnino et al. established that due to the degenerative-dystrophic changes that influence the blood vessels, the older patients are more likely to experience hemodynamic changes during spinal anesthesia. Elderly patients have less functional reserve to cope with hemodynamic changes during spinal anesthesia .
In our research, predictors of hypotension during spinal anesthesia for femoral fracture surgical treatment were the age and chronic therapy by beta blockers prior to the surgery. Similar results were reported by Oliveira et al. who pointed out the age over 45 years and female sex are predicators of hypotension during spinal anesthesia; however, these were not just patients with femoral fractures . Beta blockers reduce the sympathetic system activity and decrease the myocardial oxygen consumption. These medications have an impact on the myocardium and decrease the intensity of myocardial activity, the arterial blood pressure and the heart rate. There is no data in the literature showing that chronic treatment with beta blockers may be a predictor of hypotension during spinal anesthesia. This can be interpreted as an indication that generally patients who take beta blockers have slower heart rate; drop of systemic vascular resistance occurs as an effect of blocking the sympathetic nervous system, so they cannot adequately react to increase the heart rate, but experience an intensive drop of the heart rate and arterial pressure.
Our research has established that the examined subjects who received levobupivacaine for spinal anesthesia intraoperatively presented with slightly higher average arterial pressure. Luck JF et al. suggested that levobupivacaine used for spinal anesthesia in the elderly caused lower decrease of arterial blood pressure than bupivacaine . It was also established that the group of patients who received levobupivacaine showed higher average arterial pressure in comparison to those who received bupivacaine. Glaser et al. failed to prove that there was a difference in intraoperative values of arterial pressure between the patients in spinal anesthesia who received levobupivacaine versus those who received racemic bupivacaine. However, in this research, the group of patients was very heterogeneous regarding the age, from 18 to 85 years .
Gulek et al. established that there was no significant statistical difference between the type or dosage of the local anesthetic (bupivacaine and levopubivacaine) and arterial hypotension during spinal anesthesia in elderly patients . By comparing the preoperative values of average arterial pressure and the values at the end of the SP, it was proved that the patients have higher preoperative MAP in relation to the last value of MAP during surgery. In our research, in more than 44% of examined patients MAP was lower by 20% or more in relation to the preoperative MAP.
Hartmann et al. found that patients who consumed alcohol were at three times higher risk for arterial hypotension. Due to alcoholic neuropathy, the sympathetic nervous system is being attacked, causing orthostatic dysregulation .
Patients prone to hypotension during spinal anesthesia received a higher initial and maintenance dose of neosynephrine during the surgical procedure. In our patients, almost one-third received 150 micrograms of phenylephrine for hypotension during the surgery. Mitra et al. established that application of crystalloid solutions was efficient prior to the surgery in the aim of preventing hypotension. In their research they proved that it was more efficient to apply phenylephrine than ephedrine in the treatment of hypotension in spinal anesthesia .
Our research also recognized that it was efficient to use crystalloid and colloid solutions in the aim of filling intravascular volume in the treatment of hypotension in spinal anesthesia. If inadequate therapy response was obtained in regard to correction of volume, neosynephrine was used in the treatment of hypotension.
Our study has pointed out the predictors of hypotension in surgical management of femoral fractures in spinal anesthesia - the patient's age and taking beta blockers. It showed that levobupivacaine caused lower degree of hypotension than bupivacaine. Thus, we suggest special preparation before and during spinal anesthesia in elderly patients, and potential reduction of beta blockers immediately prior to surgery.
The main drawback of our study is its retrospective design. A prospective study should check whether levopubivacaine causes lower degree of hypotension than racemic bupivacaine in elderly patients with femoral fractures treated in spinal anesthesia, and it may represent a better choice in geriatric population.
Predictors of hypotension during surgery of patients with femoral fractures in spinal anesthesia are elderly age and preoperative use of beta blockers.
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Milica GOJKOVIC (1), Arsen UVELIN (1,2), Milanka TATIC (2,3), Vladimir VRSJAKOV (1), Dunja MIHAJLOVIC (1,2) and Aleksandra LUCIC PROKIN (4)
Clinical Center of Vojvodina, Novi Sad, Emergency Center (1)
University of Novi Sad, Faculty of Medicine Novi Sad
Department of Anesthesia and Intensive Care (2)
Institute of Oncology of Vojvodina (3)
Emergency Center, Department of Emergency Neurology (4)
Table 1. Medical history data Tabela 1. Anamnesticki podaci Fractura colli femoris Diagnosis Fractura daipahyseos femoris Dijagnoza Fractura capitis femoris Fractura subtrochanterica femoris Hemialoarthroplastica coxae sec Moore Aloarthroplastica coxae cum proth.totalis Surgery Osteosynthesis cum cunei Gamma short Operacija Osteosynthesis cum cunei Gamma long Aloarthroplastica coxae partialis Osteosynthesis femoris Hypertension arterialis/Arterijska hipertenzija Ischemic cardiac diseases/Ishemijska bolest srca Accompanying diseases Chronic obstructive lung diseases Hronicna opstruktivna bolest pluca Propratna oboljenja Diabetes mellitus type 2/Dijabetes melitus tip II Without accompanying disease Bez propratnih oboljenja Beta blocker/Beta blokatori Angiotensin converting enzyme inhibitors Inhibitori angiotenzin konvertujuceg enzima Chronic therapy Calcium channel blockers Hronicna terapija Blokatori kalcijumskih kanala Other medications/Druga terapija No therapy/Bez terapije Incidence/Ucestalost Percentage/Procenat 255 56.17 Diagnosis 25 5.51 Dijagnoza 37 8.15 137 30.18 76 16.70 77 16.92 Surgery 103 22.64 Operacija 42 9.23 37 8.13 119 26.15 303 57.50 45 8.54 Accompanying diseases 34 6.45 Propratna oboljenja 89 16.89 56 10.63 73 16.08 34 7.49 Chronic therapy 13 2.86 Hronicna terapija 69 15.20 265 58.37 Table 2. Association between medical history data and hypotension during surgery, multivariable logistic regression Tabela 2. Povezanost anamnestickih podataka i hipotenzije tokom operacije, multivarijatna logisticka regresija Age/Godine ASAC/KAUA Arterial hypertension/Arterijska hipertenzija Accompanying diseases Propratna oboljenja Ischemic cardiac diseases/Ishemijska bolest srca Chronic obstructive lung disease Hronicna opstruktivna bolest pluca Diabetes Mellitus type II/Dijabetes melitus tip II Beta blockers/Beta blokatori Chronic therapy Hronicna terapija Angiotensin converting enzyme inhibitors Inhibitori angiotenzin konvertujuceg enzima Calcium channel blockers/Blokatori kalcijumskih kanala Fractura colli femoris Diagnosis Dijagnoze Fractura diapahyseos femoris Surgery Hemialoarthroplastica coxae sec Moore Operacija Aloarthroplastica coxae cum proth.totalis Osteosynthesis cum cunei Gamma short Osteosynthesis cum cunei Gamma long OR/OV/ 95% C I/IP KS LL/DG UL/GG p 1.02 1.00 1.04 0.037 0.78 0.52 1.18 0.238 1.04 0.64 1.70 0.881 Accompanying diseases Propratna oboljenja 1.53 0.69 3.40 0.293 1.07 0.47 2.46 0.865 1.27 0.72 2.25 0.413 3.16 1.42 7.01 0.005 Chronic therapy Hronicna terapija 1.23 0.49 3.14 0.659 0.65 0.16 2.63 0.543 0.73 0.43 1.21 0.222 Diagnosis Dijagnoze 1.22 0.38 3.93 0.735 Surgery 1.05 0.52 2.09 0.899 Operacija 1.14 0.58 2.24 0.709 0.59 0.34 1.05 0.074 0.91 0.40 2.05 0.818 Legend: OR - odds ratio. 95%; CI - confidence interval for OR; LL - lower level of confidence interval; UL - upper level of the confidence interval; ASAC - American Society of Anesthesiologists Classification; p - difference between measurements Legenda: OV - odnos verovatnoce (KS - kolicnik sansi), IP - intervali poverenja za OV; DG - donja granica intervala poverenja. GG - gornja granica intervala poverenja; KAUA - Klasifikacija Americkog udruzenja anesteziologa, p - nivo razlika medu merenjima Table 3. Descriptive statistics for mean arterial pressure (MAP) Tabela 3. Deskriptivna statistika za srednji arterijski pritisak (SAP) MAP - preoperatively (1) MAP - at the end SP (2) SAP - preoperativno (1) SAP - na kraju OZ (2) Min/Min 50.00 40.00 Max/Max 163.33 120.00 MV/MV 103.24 84.82 SD/SD 14.6 13.60 Sk/Sk 0.365 0.062 Ku/Ku 1.575 -0.184 p/p 1 > 2 (p < 0.001), 1 > 3 (p < 0.001), 2 > 3 (p < 0.001) MAP - the lowest during SP (3) SAP - najnizi tokom OZ Min/Min 40.00 Max/Max 113.33 MV/MV 72.73 SD/SD 13.61 Sk/Sk 0.245 Ku/Ku -0.265 p/p 1 > 2 (p < 0.001), 1 > 3 (p < 0.001), 2 > 3 (p < 0.001) Legend: Min - minimum, Max - maximum, MV- mean value, SD - standard deviation, Sk - declivity, Ku - flattening, p - difference between measurements Legenda: Min - minimum, Max - maksimum, MV - srednja vrednost, SD - standardna devijacija, Sk - zakosenost, Ku - spljostenost, p - nivo razlika medu merenjima, OZ - operativni zahvat Table 4. Descriptive indicators for Medial pressure versus a group of drugs Tabela 4. Deskriptivni pokazatelji za medijalni pritisak u odnosu na grupu lekova Group/Grupa N/Broj MV/SV SD/SD MAP preoperatively Marcaine 333 103.01 15.31 Medijalni pritisak preoperativno Chirocaine 92 104.60 12.38 MAP - at the end of SP Marcaine 337 84.46 12.92 MP na kraju OZ Chirocaine 92 87.27 15.52 MAP - the lowest during SP Marcaine 335 70.76 13.22 MP najnizi tokom OZ Chirocaine 92 73.99 14.18 Min/Min Max/Maks Sk/Sk Ku/Ku MAP preoperatively 70.0 163.33 0.45 1.12 Medijalni pritisak preoperativno 80.0 146.67 0.89 1.57 MAP - at the end of SP 40.0 120.0 -0.01 0.00 MP na kraju OZ 50.0 120.0 -0.61 0.50 MAP - the lowest during SP 40.0 113.33 -0.22 0.26 MP najnizi tokom OZ 45.0 110.0 0.44 0.49 Legend: Min - minimum, Max - maximum, MV- mean value, SD - standard deviation, MAP - medial arterial pressure, SK - declivity, Ku - flattening, p - level of difference between measurements Legenda: Min - minimum, Maks - maksimum, SV - srednja vrednost, SD - standardna devijacija, MP - medijalni pritisak, OZ - operativni zahvat, SK - zakosenost, Ku - spljostenost, p - nivo razlika medu merenjima