|Year : 2017 | Volume
| Issue : 4 | Page : 1238-1243
Hypotensive epidural anesthesia in patients with preoperative renal dysfunction presenting for hip arthroplasty
Ahmed S El-Gebaly, Ahmed Abd El-Aziz Shama, Mohamad Gamal El-Maw
Department of Anesthesia and PSICUD, Faculty of Medicine, Tanta University, Tanta, Egypt
|Date of Submission||20-Feb-2017|
|Date of Acceptance||02-Jul-2017|
|Date of Web Publication||04-Apr-2018|
Ahmed S El-Gebaly
Department of Anesthesia and ICU, Faculty of Medicine, Tanta University, Tanta 31511
Source of Support: None, Conflict of Interest: None
To investigate the benefits and safety of hypotensive epidural anesthesia (HEA) in comparison with normotensive epidural anesthesia in patients with preoperative renal dysfunction presenting for hip arthroplasty.
HEA is one of the anesthetic techniques used to reduce perioperative blood loss for total hip replacement. The technique includes a combination of an extensive epidural block and an intravenous infusion of low-dose epinephrine (1–5 μg/min) to adjust and control the mean arterial blood pressure together with preserving central venous pressure and cardiac output.
Patients and methods
Forty adult patients of both sexes undergoing primary unilateral hip arthroplasty, ranging in age from 60 to 74 years, ASA II–III with mild renal dysfunction were divided into two groups: group I received epidural anesthesia with strict preservation of the mean arterial blood pressure (65–90 mmHg) during surgery using vasopressors, fluids, and/or blood transfusions and group II received epidural anesthesia and hypotension was induced by maintaining the mean arterial blood pressure at 55–60 mmHg during the entire surgery.
The heart rate and the mean arterial blood pressure showed a significant difference between the two groups at 15, 30, 45, 60, and 90 min intraoperatively (P < 0.05). Serum creatinine was significantly increased in group II at 6 h (P < 0.05) and postoperatively, with a significant decrease in creatinine clearance in group II at 24 h postoperatively (P < 0.05). The mean values of blood urea showed a significant increase in group II than group I after 6, 12, 24, and 48 h postoperatively. The duration of surgery was significantly different between the groups; it was longer in group I than group II (P < 0.05). Blood loss and blood transfusion were significantly decreased (P < 0.05) in group II than group I. The mean epinephrine infusion rate was significantly increased in group I (P < 0.05). Hematocrit was significantly decreased in both groups postoperatively (P < 0.05).
HEA is superior to normotensive epidural anesthesia in patients with renal impairment undergoing hip arthroplasty in the form of decreased blood loss and the need for blood infusion, provides a clear surgical field, and leads to an improvement in cement fixation and decreased incidence of postoperative deep vein thrombosis and blood loss, with no evidence of acute kidney injury postoperatively.
Keywords: anesthesia, arthroplasty, epidural, hip, hypotensive, impairment normotensive, renal
|How to cite this article:|
El-Gebaly AS, Abd El-Aziz Shama A, El-Maw MG. Hypotensive epidural anesthesia in patients with preoperative renal dysfunction presenting for hip arthroplasty. Menoufia Med J 2017;30:1238-43
|How to cite this URL:|
El-Gebaly AS, Abd El-Aziz Shama A, El-Maw MG. Hypotensive epidural anesthesia in patients with preoperative renal dysfunction presenting for hip arthroplasty. Menoufia Med J [serial online] 2017 [cited 2020 Feb 17];30:1238-43. Available from: http://www.mmj.eg.net/text.asp?2017/30/4/1238/229199
| Introduction|| |
Preoperatively, 80–90% of cases of renal failure in patients with chronic renal dysfunction (CRD) are triggered by episodes as short as 60 min of relative hypovolemia and reduced renal blood flow. For these reasons, anesthetic management of patients with CRD is based on preservation of central venous pressure (CVP) and arterial blood pressure. CRD is associated with an increased risk of cardiovascular disease such as myocardial infarction and heart failure.
An increase in serum creatinine is used routinely to detect perioperative renal impairment and most studies of postoperative renal function have used this variable. However, this technique suffers also from a lack of sensitivity. The glomerular filtration rate (GFR) could be reduced by 50–70% without leading to an increase in the serum creatinine concentration because the decrease in glomerular filtration of creatinine is balanced by increased creatinine secretion by cells in the proximal tubule cells. Also, serum creatinine is affected by a number of extra renal variables, especially in the postoperative period. These include fluid loading and the resultant dilution, variable muscle mass, and a high metabolic rate, all of which may contribute toward misleading information.
Creatinine clearance has long been used to assess the ability of the glomeruli to filter creatinine. However, the limitations of creatinine clearance in assessing GFR are well recognized, especially in the postoperative period. The main problems with the technique are overestimation of GFR because of tubular secretion and the need to measure the urine volume accurately.
Hypotensive anesthesia, induced with general anesthesia, typically results in a reduction in glomerular filtration and urine production; however, deterioration in renal function postoperatively has not been observed. However, these studies have all been carried out in patients with normal renal function.
Hypotensive epidural anesthesia (HEA) involves substantial, if not complete, sympathectomy, and cardiac output and CVPs may be maintained with a low-dose vasopressor infusion. In a large series of patients with normal preoperative renal function who received HEA, postoperative renal dysfunction was not observed. Patients with CRD could potentially benefit from HEA, which offers many advantages in total hip replacement, such as reduced blood loss and blood transfusion, a low rate of venous thromboembolism, improved cement fixation, and a low postoperative mortality rate.
The aim of this study is to investigate the benefits and safety of HEA in comparison with normotensive epidural anesthesia in patients with preoperative renal dysfunction presenting for hip arthroplasty.
| Patients and Methods|| |
After receiving approval from the institutional ethics committee, an informed written consent was obtained from 40 ASA physical status II and III patients ranging in age from 60 to 75 years undergoing primary unilateral hip arthroplasty; they were classified randomly into two equal groups of 20 patients each.
Group I (normotensive epidural anesthesia)
Patients in this group (20 patients) were operated under epidural anesthesia with strict preservation of the mean arterial blood pressure (65–90 mmHg) during surgery using vasopressors up to epinephrine infusion, fluids, and/or blood transfusions.
Group II (hypotensive epidural anesthesia)
Patients in this group (20 patient) were operated on under epidural anesthesia and hypotension was induced by maintaining the mean arterial blood pressure at 55–60 mmHg during the entire duration of surgery using a minimal dose of intravenous vasopressors (low-dose epinephrine infusion) and crystalloids to maintain CVP at normal baseline values more than or equal to 5 cm H2O and duration of hypotension was monitored until 90 min intraoperatively.
Patients with renal dysfunction were diagnosed preoperatively by a serum creatinine of 2–3 mg/dl and a creatinine clearance of 40–60 ml/min, and were included in the study. Acute postoperative kidney injury was defined postoperatively as a percentage increase in serum creatinine of more than or equal to 50% (1.5 × baseline) or a reduction in creatinine clearance to less than 15 ml/min.
For all patients, full clinical examination and laboratory investigations of renal, hepatic functions as well as cardiovascular status were performed to exclude cases with a significant impairment in renal functions, if serum creatinine more than 3 mg/dl, creatinine clearance less than or equal to 40 ml/min, and patients on dialysis, those with severe impairment of hepatic functions as evidenced by liver function tests and ultrasonography, cardiovascular instability as severe hypertension more than or equal to 160/110 mmHg, uncontrolled arrhythmias, low fixed cardiac output conditions (such as severe aortic and mitral stenosis, severe pulmonary hypertension, and core pulmonal), revision of total hip replacement, recent cerebral stroke for fear of recurrence or cerebral insufficiency and for medico legal aspects, patients with coagulopathies and impaired platelet functions, drug sensitivity to bupivacaine, severe spinal deformity such as kyphoscoliosis, uncooperative patients such as those with psychosis, and patients with infection at the site of injection.
For all patients in the preoperative warmed room, two wide-bore intravenous lines were inserted, a uretheral catheter, and monitors such as ECG, peripheral oxygen saturation SpO2, noninvasive blood pressure, invasive blood pressure, and CVP were set up.
The duration of surgery was monitored from the onset of the local anesthetic injection and the targeted mean blood pressure in both groups until the end of the procedure. Blood loss was monitored using subjective methods and measuring the volume of blood suctioned and the soaked swabs. The method for estimation of blood loss involved measurement of blood in the surgical suction container and visual estimation of the blood on surgical sponges and pads; a fully soaked sponge (4 × 4) can retain 10 ml of blood, whereas a soaked pad can retain 100–150 ml of blood. More than 900 ml was considered a significant loss. All patients were prehydrated with warmed lactated ringer 6–10 ml/kg about 1 h preoperatively.
HEA was induced by injecting 20–30 ml 0.5% plain bupivacaine through a 17 G Tuohy needle inserted at L1–L2 interspaces. An epidural catheter was placed, through which additional local anesthetic could be injected incrementally according to the level of block and the degree of hypotension. The catheter was used for postoperative epidural analgesia for 24–48 h.
Immediately after the epidural local anesthetic was injected, an intravenous infusion of epinephrine was started through a central venous catheter. The epinephrine infusion that we used included 1 mg of epinephrine in 250 ml of normal saline (4 μg/ml). The initial infusion rate in group II was usually 1–2 μg/min (15–30 ml/h) (15–30 drop/min), but was adjusted during the next 10–20 min to achieve the target MAP. Usually, this degree of hypotension was achieved within 10–15 min.
Our assessment included measurement of heart rate (HR), mean arterial blood pressure, and CVP preoperatively, 15, 30, 45, 60, and 90 min intraoperatively, and 6, 12, and 24 h postoperatively. Urine output measurement was performed during the first 3 days postoperatively. Crystalloid intake was assessed intraoperatively. Epinephrine infusion rate was determined. Estimations of blood urea and serum creatinine were performed preoperatively at 6 and 12 h, and 24, 48, and 72 h postoperatively by laboratory analysis. Creatinine clearance was measured 24, 48, and 72 h postoperatively; blood loss, blood transfusion, and the duration of surgery for all patients were the primary outcome measures and were recorded intraoperatively and postoperatively. The hematocrit value was measured preoperatively and postoperatively, and any complications were recorded.
Pain and swelling of the legs are relatively common presenting complaints for deep vein thrombosis (DVT) along with wound sepsis in primary care practice; thus, it must be observed in all patients.
Statistical analysis of the data
Sample size calculation was based on the fact that ∼18 patients were required in each group with a power of 0.80 and a level of significance of 5%. Data were entered into the computer and analyzed using IBM SPSS Statistics for Windows (version 20.0, released 2011; IBM Corp., Armonk, New York, USA).
| Results|| |
Demographic data (age, weight, and sex) were comparable, with no statistical significance. On comparing the study groups, HR showed no significant difference between both groups preoperatively and then HR decreased significantly (P< 0.05) in group II at 15, 30, 45, 60, and 90 min (64.45 ± 12.50, 65.35 ± 8.89, 68.90 ± 13.74, 67.60 ± 11.17, and 69.20 ± 9.61 beats/min), respectively, intraoperatively than in group I (81.05 ± 12.21, 81.45 ± 13.41, 82.40 ± 11.87, 80.20 ± 13.60, and 77.80 ± 13.36 beats/min, respectively), and there was no significant difference at 6, 12, and 24 h postoperatively [Table 1].
|Table 1: Demographic data, heart rate, mean arterial pressure, and central venous pressure in the groups studied|
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In terms of MAP, there was no significant difference between both groups in the preoperative values; it was significantly decreased in group I compared with group II at 15, 30, 45, 60, and 90 min intraoperatively, respectively. There was no significant difference between both groups at 12 and 24 h postoperatively (P > 0.05; [Table 1]).
CVP preoperatively at 15, 30, 45, 60, and 90 min intraoperatively and at 6, 12, and 24 h postoperatively showed no significant difference between both groups (P > 0.05; [Table 1]).
Serum creatinine showed no significant difference between both groups preoperatively and at 12, 24, 48, and 72 h postoperatively, with a significant increase in group II at 6 h postoperatively (P< 0.05). In terms of creatinine clearance, there was no statistical difference preoperatively and at 48 and 72 h postoperatively, with a significant decrease in group II at 24 h postoperatively (P< 0.05). There was no statistically significant difference between both groups in blood urea values preoperatively and at 72 h postoperatively, with a significant increase in group II compared with group I at 6, 12, 24, and 48 h postoperatively (P< 0.05; [Table 2]).
|Table 2: Serum creatinine, creatinine clearance, and blood urea among the groups studied|
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The duration of surgery was significantly decreased in group II compared with group I, with significantly decreased blood loss and blood transfusion. Crystalloid infusion showed no significant difference between both groups (P< 0.05; [Table 3]).
The epinephrine infusion rate was significantly increased in group II (3.03 ± 0.538 μg/min) compared with group I (1.285 ± 1.02 μg/min) (P< 0.05).
The mean values of hematocrit in both groups was decreased significantly in group I, from a preoperative mean value of 40.400 ± 2.798% to a postoperative mean value of 36.550 ± 2.911%, and decreased significantly in group II, from a preoperative mean value of 40.350 ± 2.434% to a postoperative mean value of 33.550 ± 1.234%, with an insignificant difference between both groups preoperatively and a significant decrease in group II (33.550 ± 1.234%) than group I (36.550 ± 2.911%) postoperatively (P< 0.05).
In both groups, only one patient suffered from acute kidney injury (increase in serum creatinine by ≥0.3 mg/dl within 48 h or increase in serum creatinine to ≥1.5 times baseline, which is known or presumed to have occurred within the past 7 days, or urine volume <0.5 ml/kg/h for 6 h), two patients from group I developed a complication of postoperative blood loss (>900 ml), four patients from group I and only one patient from group II developed DVT (diagnosed by duplex venous ultrasound) as a complication, three patients from group I and four patients from group II developed a postoperative wound infection (they were treated with proper antibiotics according to culture and sensitivity and kidney functions reverted to previous levels after 3 days without the need for dialysis) as a complication, four patients from group I and one patient from group II showed no radiological evidence of improved fixation of cemented acetabular components and only one patient from each group had in-hospital mortality (because of cerebral stroke, which was not related to the study).
| Discussion|| |
Chronic kidney disease is a risk factor for severe postoperative complications, such as acute renal failure and cardiovascular complications, which are associated with increased morbidity and mortality. Acute kidney injury is a syndrome of abrupt loss of kidney function, often with oliguria, which is strongly associated with increased early and long-term patient morbidity and mortality, as well as the subsequent development of chronic kidney disease. In the hospital setting, AKI-preventive measures continue to be adequate hemodynamic control, hydration, hematocrit, and oxygen profiling, and avoidance of nephrotoxic drugs.
All patients were geriatrics and had renal impairment; thus, it might be considered risky to expose them to HEA in a major surgery such as hip arthroplasty with expected blood loss, but the benefits of HEA in these patients together with the lack of clinical evidence of postoperative acute kidney injury spurred us to carry out this study; therefore, in our study, we aimed to investigate the relation between the degree of renal impairment in patients diagnosed preoperatively with mild renal dysfunction undergoing primary hip arthroplasty who were subjected to hypotensive anesthesia through a special epidural technique together with an epinephrine infusion to preserve cardiac output and CVP.
The circulatory effects of HEA are because of both the extensive sympathetic block from the epidural blockade and the low-dose intravenous epinephrine infusion. The sympathetic block from the epidural anesthesia dilates the arterioles and veins and suppresses both the inotropic and the chronotropic activity of the heart. If untreated, this leads to acute hypotension, bradycardia, and a significant reduction in cardiac output. Epinephrine modifies the response by preserving preload (CVP) and stimulating the adrenergic receptors in the heart to maintain HR and stroke volume. Sharrock used an epinephrine infusion to control MAP, cardiac output, HR, and CVP and showed that epinephrine infusion yielded the best results in controlling both MAP together with maintaining normal cardiac output and CVP. Epinephrine is the only vasopressor that we have used that can result in a normal cardiac output with hypotension. β-Agonists, such as isoproterenol or dobutamine, lead to a decrease in filling pressure and an increase in HR. In many cases, this is associated with a decrease in cardiac output and it can be difficult to stabilize the MAP.
Zayas and Badingstudied the hormonal and renal response to thoracic epidural anesthesia and extensive spinal anesthesia to HEA and showed that when intravenous vasopressors or crystalloid were used to maintain blood pressure at 55–60 mmHg, renin and noradrenaline concentrations were decreased and renal blood flow was relatively well maintained.
Dauphin et al.reported on the combination of epidural anesthesia with light general anesthesia for total hip arthroplasty; the number of patients who required blood transfusion was significantly decreased compared with those who received general anesthesia.
It has been reported that lower arterial BP, lower CVP, and, most importantly, lower peripheral venous pressure in the surgical wound seem to explain the lower blood loss intraoperatively and postoperatively in patients receiving regional anesthesia. Modig reported that the latter observation was strengthened by the significant correlations between intraoperative peripheral venous pressure and intraoperative blood loss. Our results are consistent with the results of Niemi et al., who reported that HEA significantly decreased the percentage of patients who required intraoperative blood transfusion.
In terms of the postoperative complications in our study, we found the following.
In group I, four patients developed DVT, whereas only one patient in group II developed DVT. The rate of DVT was related to the duration of surgery. Patients in whom surgery was completed in 70 min or less had a DVT rate of 9%, whereas the rate was 20% when surgery lasted more than 70 min. The rate of proximal DVT was also lower in patients receiving epinephrine (2.4%) compared with crystalloid (9.3%). Low-dose epinephrine appeared to provide the most benefit in reducing DVT when the surgery lasted over 70 min,.
Minimization of intraoperative blood loss by hypotension may reduce DVT by several mechanisms. First, perioperative disturbances in coagulability are, in part, related to perioperative blood loss. Intraoperatively, there is a reduction in circulating anticoagulants, such as antithrombin I1, because of hemodilution and consumption. Postoperatively, the rebound in factor VIII levels, etc., which produces the hypercoagulable state, is also related to the degree of blood loss.
In addition, if too much intravenous fluid or blood is infused during surgery to replace excessive blood loss, hypothermia may occur. This results in peripheral vasoconstriction, leading to venous stasis in the extremities, thereby predisposing to DVT.
Some limitations of this study should be noted. First, although no major complications were observed and some parturients required conversion to general anesthesia, we did not assess the parturients' satisfaction. Second, the sample size was small. The study included only 40 participants who fulfilled all the inclusion criteria and had undergone elective surgeries of unilateral hip arthroplasty. The sample size was restricted to 40 cases because of logistical reasons and limited operation type varieties. Third, the correlation between the dose of the drugs injected and the duration of anesthesia and postoperative analgesia was not assessed; also, assessment of cognitive and cardiac effects following surgery was beyond the scope of our study.
| Conclusion|| |
HEA is superior to normotensive epidural anesthesia in patients with renal impairment undergoing hip arthroplasty in the form of decreased blood loss and need for blood infusion, provides a clear surgical field, together with improvement of cement fixation and decreased incidence of postoperative DVT and blood loss, with no evidence of acute kidney injury postoperatively.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3]