Study of Failed Spinal Anesthesia Undergoing Caesarean Section and Its Management

Transcription

1 Original Article Study of Failed Spinal Anesthesia Undergoing Caesarean Section and Its Management Pokharel A Consultant Anaesthesiologist, Department of Anaesthesia, National Academy of Medical Sciences, Bir Hospital, Kathmandu, Nepal ABSTRACT Introduction: Spinal anesthesia is most common procedure in our peripheral hospital. Failure of spinal anesthesia is very common, which may be due to technical error or ineffective drugs. So in peripheral setting where there are lack of adequate facility repeating spinal anesthesia is good alternative. Methods: A retrospective study was performed by in 1197 parturient undergoing elective and emergency caesarean section under spinal anesthesia by same anesthesiologist and his assistant from December 2008 to April 2011 in maternity ward in Mechi Zonal Hospital, in order to determine the incidence of complete and partial failure of spinal anesthesia. Partial failure is taken as a case in which patients could not move their lower limb but still felt pain sensation at incision sites. A routine spinal technique using intrathecal 0.5% heavy bupivacaine 2.4 ml (12 mg) was administered with a 26-gauge Quincke spinal needle. Data were collected to determine incidence of failure of spinal anesthesia and effectiveness of repeat spinal anesthesia. Results: Total numbers of failed spinal anesthesia in first attempt were 1.5% of total cases (i.e.18 cases). Out of these, complete failure requiring repeat spinal was 17 cases and in one case block was up to T12 spinal level in first attempt so spinal anesthesia is repeated. Out of these 18 cases, after repeat spinal 17 (94.45%) cases were having effective block, in one case (5.55%) there was no effect of repeat spinal anesthesia so conversion to general anesthesia was done. Conclusion: Spinal anesthesia using bupivacaine 12 mg (2.4 ml) produces reliable anesthesia for caesarean section. After failure of first attempt repeat dose of 9 mg (1.8 ml) showed its effectiveness of 94.45% without extra side effects. The outcome of repeat spinal anesthesia seems effective with no extra side effect that we can easily practice in the peripheral setting where there is lack of general anesthesia facility as well as in central setting to avoid the sudden disastrous effect of general anesthesia. Key words: Parturient; caesarean section; intrathecal; spinal anesthesia; general anesthesia INTRODUCTION Spinal anesthesia has evolved greatly since its introduction in 1899 to clinical use by August Bier. It is the most common technique for infra umbilical procedures. There is a demonstrable reduction in mortality and morbidity with regional techniques 1.The level of competency in administering spinal anesthesia Correspondence : Dr. Abhay Pokharel, Consultant Anesthesiologist, National Academy of Medical Sciences, Bir Hospital, Kathmandu, Nepal. - a_pokharel@yahoo.com is attained relatively quickly, with a >90% success rate after 40 to 70 supervised attempts 2. Not all spinal anesthesia is successful, so general anesthesia is readily and hastily advanced. This occurs commonly at the expense of patient choice and the benefits of regional anaesthesia. Failed spinal anaesthesia is loosely defined and not addressed in the general literature. Onset of action differs between various intrathecal anesthetic agents. Bupivacaine is one of extensively studied and well understood of these agents. A bupivacaine spinal Volume 11 Number 2 Jul-Dec

2 anaesthesia is considered to have failed if anesthesia and analgesia have not effected within 10 minutes of successful intrathecal deposition of heavy bupivacaine and 25 minutes for plain bupivacaine 3, 4. Ropivacaine is 50 to 60% as potent as spinal bupivacaine; and equipotent doses of ropivacaine will have similar recovery times as bupivacaine 5. In the training environment the incidence of failed spinal anesthesia can be as high as 25% or 1 in 6, and current literature however, quotes this incidence to be in the region of 5% 6. The combined spinal/epidural technique appears to be associated with a higher incidence of failed spinal anesthesia. 6 Latency of block varies from 10 to 60 minutes and is shorter when hyperbaric solution is used. Spread of analgesia continues for more than 30 minutes after plain bupivacaine 7. This process is completed in approximately 90 to 120 minutes. Mechanism of Action after successful intrathecal injection, the injectate undergoes three important phases 4. As CSF volume varies from 28-81ml, drugs mixes with CSF and gets diluted in for first 1-2 minutes, in the next 2 to 6 minutes, the injectate then diffuses by virtue of molecular motion and is absorbed into the nervous tissue. Concentration is thus reduced further. The injectate is then distributed and attaches to receptors on the nerve roots and in this manner clinical effect is obtained. Finally, vascular absorption and elimination through capillary bed, parenchyma and arachnoid villi takes place. Technical errors are common causes of failed spinals like: drug deposition at lower spinal level than surgical site, improper rate of injection, failure to recognize dural puncture, needle partly inside/outside dural sac, patient co-operation, needle in ventral epidural space and lateral horizontal position (25%). Chemical interactions are also contributory like: bloody tap causes hydrolysis of ester type anesthetics by pseudo-cholinesterase, concentration errors, loss of potency by prolonged exposure to light, high CSF ph, glucose causes hyperalgesia and spotty anesthesia 4. Management of failure of a spinal anesthetic is an event of significant concern for both patient and anesthetist even when it is immediately apparent. The management options are limited; so, the first rule is to expend every effort in its prevention. The onset of spinal anaesthesia is rapid in most patients; it can be slow in some; so, tincture of time should always be allowed 9. If block has not developed within 15 min, some additional maneuver is needed. Repeating the procedure or conversion to general anaesthesia is the only option 8. Patchy block that appears adequate in extent, but the sensory and motor effects are incomplete, if becomes apparent after surgery starts, the options are to use systemic supplementation and may not be necessary to for general anesthesia. Sedative or analgesic drugs are usually sufficient, when patient anxiety is a major factor. Infiltration of the wound and other tissues with local anaesthetic by the surgeon may also be useful in such situations. Repeating the block, especially in response to a poor quality block, may lead to excessive spread, so it may be argued that a lower dose should be used to reduce the risk of this possibility 10. Recourse to general anaesthesia 8 : There are many ways in which an inadequate block might be rescued, but there is a limit to how much discomfort or distress an individual patient can tolerate, so general anesthesia must also be considered. METHODS A retrospective study was performed in 1197 parturient undergoing elective and emergency caesarean section under spinal anaesthesia from December 2008 to April 2011 maternity ward in Mechi Zonal Hospital, in order to determine the incidence of complete and partial failure of spinal anaesthesia. As this is a Zonal Hospital only ASA grade 1 and 2 patients undergoing elective or emergency caesarean section were taken for operation due lack of man power and intensive care facility. Detail preoperative anaesthetic check-up was done to all patients. After coming to operation theatre all patients were preloaded with 500 ml of Ringer Lactate. Monitor was attached and preoperative vitals are taken. Then patients were kept in sitting position and after all aseptic precaution 26-gauge Quincke spinal needle was inserted at 3 rd or 4 th lumbar space. After free flow of cerebrospinal fluid (CSF) 5 ml syringe containing 2.4 ml of 0.5% heavy bupivacaine (sensorcaine Astra-Zeneca) was attached to spinal needle and drug was administered. The spinal needle was manipulated until free flow of CSF was achieved. 12 Volume 11 Number 2 Jul-Dec 2011

3 Patients were immediately kept on supine position with a wedge under the right buttock and vitals were monitored. Usually effect were noted within five minutes, those who do not showed effectiveness in 5 minutes were watched for another 5 minutes and then they were tested for temperature (cold) sensation, pain at incision site and level of pain sensation block was and motor response by asking them to raise their legs. Patients who feel pain after pin prick at the site of incision was considered failed spinal, so spinal anaesthesia were repeated. Those who developed motor block of lower limb were kept on left lateral position to repeat spinal anaesthesia and those who did not develop motor block was again kept on sitting position to repeat spinal anaesthesia. While giving repeat spinal, 1.8 ml (9 mg) 0.5% of heavy bupivacaine was taken from new ampoule and was given only after free flow of CSF on aspiration. Again patients were watched for effect of spinal to come. Effective spinal anaesthesia was ascertained when patients feel no pain at incision site and if patients felt traction pain during surgery intravenous anaesthesia was supplemented. Although all patients were monitored but especial attention was given to those patients who were given repeat spinal because of theoretical chance of more side effects like high spinal block, post-dural puncture headache. Intraoprative pulse, blood pressure every five minutes, ECG and pulse oximetry were monitored. Symptomatic management of side effect was done as shown in table - 4. After completion of surgery patients were shifted to ward and patients were observed for PDPH, postoperative nausea and vomiting and residual effects of spinal anaesthesia. RESULTS Data were collected to determine incidence of failure of spinal anaesthesia and effectiveness of repeat spinal anaesthesia. Patients were all female of age group years. Total failures requiring repeat spinal was 18 cases (1.5% of total cases), among these 17 cases were complete failure with no effects and in one case block was inadequate up to T12 level. Out of these 18 cases, 1 case (5.55%) of repeat spinal was failed and converted to general anaesthesia, as there was no block after repeat spinal. In another one case block was up to T8 sensory block (5.55%) even after repeat spinal and then intravenous anaesthesia was supplemented. Spinal anaesthesia using bupivacaine 12 mg (2.4 ml) produces reliable anaesthesia for caesarean section. After failure repeat dose of 9 mg (1.8 ml) is highly effective without extra side effects. The outcome of repeat spinal is so effective with no side effect in 10 cases (55.55%), hypotension in 4 (22.22%) cases, 1 (5.55%) case both hypotension and bradycardia, 1 (5.55%), bradycardia cases, high spinal 1 (5.55%) cases, low spinal. Among 18 cases only 1 cases developed high spinal block, no patient with repeat spinal developed spinal headache. Table 1. Demography of failed cases Age 16-39yrs Sex Female ASA 1/ASA2 805/392 Weight in kg Duration of surgery min Table 2. Spinal anesthesia Attempts Success Failure Total First (2.4ml) 1179 (98.5%) 18 (1.5%) 1197 Second (1.8 ml) 17 (94.5%) 1 (5.5%) 18 Table 3. Level of Block following second dose of spinal anesthesia Block level No of patient T 1 T 2 2 (11.11%) T 3 7 (38.88%) T 4 2 (11.11%) T 5 4 (22.2%) T 6 T 8 Failed 1 GA (5.55%) Table 4. lntraoperative events Intraoperative No. of Treatment given % events cases Uneventful 10 None 55.56% Hypotension 4 Mephenteramine 22.22% Bradycardia 1 Atropine 5.55% High spinal 1 Difficulty in 5.55% block breathing so bag mask ventilation Low spinal block 1 ketamine supplementation 5.55% Hypotension Bradycardia 1 Mephenteramine and atropine 5.55% Volume 11 Number 2 Jul-Dec

4 DISCUSSION It is unlikely that a spinal anesthesia will work if it has not done so within 10 minutes of deposition (hyperbaric bupivacaine) 8. Having discussed how spinals work, the fate of the injectate and the causes of failed spinal anesthesia, it follows that it is feasible to repeat the injection without increased risk of a higher dermatome spread. The Royal College of Anaesthetists suggest that, in keeping with the best practice, the conversion rate from neuraxial anaesthesia to general anaesthesia should be less than 1% for elective caesarean section and less than 3% for non-elective caesarean section 12. B. L. Sng, Y. Lim, A. T. H. Sia 16 showed failure rate of 0.5% (4/800) requiring conversion from spinal anaesthesia to general anaesthesia is consistent with this standard. This was despite using a 10-mg dose of heavy bupivacaine, which is lower than doses used in other centre and contemporary anaesthesia texts 11, 13, 14. Specifically, this dose is lower than the previous established ED95 (dose of drug that is effective in 95% of population) of 11.2 mg of hyperbaric bupivacaine with intrathecal fentanyl 10 l micro g plus morphine 200 micro g 15. In this study 12 mg of hyperbaric bupivacaine was used, which is the dose we use in our daily practice and incidence of failed spinal was 1.5% which is similar with The Royal College of Anaesthetists suggestion. Repeat injection, especially in response to a poor quality block, may lead to excessive spread, so it may be argued that a lower dose should be used to reduce the risk of this possibility 10, although there is no such study available regarding the dose of the hyperbaric bupivacaine, so 9 mg of hyperbaric bupivacaine was given. It is common practice in the United Kingdom to use higher volumes for spinal anaesthesia and this has happened without higher incidence of complications 19. Immediate conversion to general anaesthesia (GA) after a single failed spinal anaesthesia can be safely avoided. Some patients express their preference for regional anaesthesia and such a choice must be protected. Often the choice of regional may have been motivated by a potentially difficult airway and sudden conversion to GA can be disastrous. Draping for surgical sterility has to be done only when the anesthetist is satisfied about adequacy of the block since repositioning may be necessary. If the block was initially not technically difficult and the surgical procedure allows for extra time to redo the intrathecal injection, it should, by all means, be repeated. In some patients, however, there is general resistance to local anaesthetics and a repeat successful intrathecal injection of local anaesthetic agent produces no analgesia/anesthesia 17, 18. In the current literature 19 only two attempts are recommended since multiple punctures can inflict nerve injury and predispose to haematoma formation. In our peripheral set up where there is lack of adequate facility of giving general anesthesia as well as trained man power and also where it takes hours to reach higher centre this study will helpful for our society for better outcomes for mothers and newborns. CONCLUSION The importance of regional anesthesia over general anesthesia cannot be over-emphasized. An attempt to make regional anaesthesia work is a worthwhile endeavor. It is not necessary to immediately convert to general anesthesia if a single shot spinal anaesthetic injection failed to produce analgesia/anesthesia. A repeat intrathecal injection is safe to perform and general anesthesia can be avoided. REFERENCES 1. Rodgers A, Walker N, Schug. Reduction of post operative pain.2000; 321: Konrad C. Schupfer G. Wietlisbach M. Gerber H: Learning manual skills in anaesthesiology.a&a 1998; 86: WF Casey: Spinal Anaesthesia-Practical Guide Vincent J Collins: Principles of Anesthesiology; 3rd Edition G Hocking, JAW Wildsmith: Intrathecal drug spread: BJA 2004; 93: Spencer S. Liu, Susan B. McDonald: Current Issues in Spinal Anaesthesia: ASA M. Tuominen: Review; Bupivacaine Spinal Anaesthesia: Acta Anaesthesiol Scand 1991; 35: P. D. W. Fettes, J.-R. Jansson and J. A. W. Wildsmith: Failed spinal anaesthesia: mechanisms, management, and prevention: BJA 2009; 102(6): Carpenter RL, Hogan QH, Liu SS, Crane B, Moore J. Lumbosacral cerebrospinal fluid volume is the primary determinant of sensory block extent and duration during spinal anaesthesia. Anesthesiology 1998; 89: Deshpande S, Idriz R. Repeat dose after an inadequate spinal block. Anaesthesia 1996; 51: Saravanan S, Robinson A P, Qayoum Dar A, ColumbMO, Lyons G R. Minimum dose of intrathecal diamorphine required to prevent intraoperative supplementation of 14 Volume 11 Number 2 Jul-Dec 2011

5 spinal anaesthesia for Caesarean section. Br J Anaesth 2003; 91: Lack J A, White L A, Thomas G M, Rollin A M. Technique of anaesthesia for caesarean section. Raising the standard: a compendium of audit recipe. London: The Royal College of Anaesthetists, Demiraran Y, Ozdemir I, Kocaman B, Yucel O. Intrathecal sufentanil (1.5 microg) added to hyperbaric bupivacaine (0.5%) for elective cesarean section provides adequate analgesia without need for pruritus therapy. J Anesth 2006; 20: Santos A C, Finster M. Obstetric anaesthesia. In: Barash P G, Cullen B F, Stoelting R K, eds. Clinical Anaesthesia. Philadelphia: Lippincott Williams and Wilkins, 2006: Ginosar Y, Mirikatani E, Drover D R, Cohen S E, Riley E T. ED50 and ED95 of intrathecal hyperbaric bupivacaine co administered with opioids for cesarean delivery. Anesthesiology 2004; 100: B. L. Sng, Y. Lim, A. T. H. Sia An observational prospective cohort study of incidence and characteristics of failed spinal anaesthesia for caesarean section International Journal of Obstetric Anaesthesia (2009) 18, Batas D, et al. Resistance to local anaesthetics: a case report. short/brjana_el; Schmidt SI, Moorthy SS, Dierdorf SF, Anagnostou JM. A series of truly failed spinal anesthetics. J Clin Anesth 1990; 2: Lapale Moipolai, Failed spinal anesthesia, SAJRA 2011;15:18-20 Volume 11 Number 2 Jul-Dec