Evaluation of changes in serum phenytoin level after craniotomy and its relation to intra operative blood loss

Abstract

a b s t r a c tProblems considered: Phenytoin is the drug of choice for post operative seizures while some studies have shown lack of efficacy of phenytoin in reducing seizure frequency after craniotomy, which in turn may be due to fall in plasma phenytoin levels after craniotomy. Aims: The aim of the study is to describe changes, if any, in plasma phenytoin levels after craniotomy and its relation to intra operative blood loss. Methods: This was a prospective study in which total of 50 consecutive patients were enrolled after taking written informed consent, who were either on oral phenytoin for at least 7 days or had received intravenous loading dose prior to craniotomy. All patients had serum phenytoin levels monitored 24 h pre operatively, immediately pre craniotomy before skin incision and post craniotomy after skin closure, and 24 h after craniotomy. All patients had intra operative blood loss calculated with help of modification of Gross formula. Results: There was a mean fall of 23.6% in serum phenytoin level immediately following craniotomy which was statistically significant. Furthermore, analysis indicated that greater the operative duration and blood loss, greater was the fall in serum phenytoin level. Conclusions: The study concludes that routine measurement of perioperative serum phenytoin levels in high risk patients may be of benefit in preventing post craniotomy seizures and an additional bolus dose should be given towards the end of surgery to patients with significant intra operative blood loss. ScienceDirect journal homepage: www.elsevier.com/locate/ijnt t h e i n d i a n j o u r n a l o f n e u r o t r a u m a 1 1 ( 2 0 1 4 ) 1 0 9 e1 1 2 http://dx.

To Study Perioperative Changes in Plasma Phenytoin Levels in Patients with Brain Tumor Undergoing Craniotomy and Its Correlation with Postoperative Seizures

“…It is important to note that a sudden drop in perioperative phenytoin levels could potentially increase the risk of postoperative seizures, similar to the abrupt withdrawal of an anticonvulsant drug in a nonsurgical setting. 3,4,27,28 Maintaining a therapeutic level of phenytoin is crucial for effective seizure control, as patients with subtherapeutic levels are more susceptible to seizures. 4,13 The occurrence of postoperative seizures is a complex phenomenon, and subtherapeutic level of phenytoin is one of the contributing Table 4 Comparison of all parameters used in study between two groups, one having seizures and other not having any seizures in their post-operative period Based on this study, it is suggested that a loading dose of 7 to 15 mg/kg may be administered after the closure of dura to prevent a sudden drop in phenytoin levels in the immediate postoperative period, as recommended by other researchers as well.…”

“…The incidence of postcraniotomy seizures varies significantly, ranging from as low as 3% to as high as 92%. [1][2][3][4][5] These variations are closely linked to the specific site of the surgical procedure and the nature of the underlying pathology. Of particular concern is the observation that the greatest risk of seizures is within the initial 48 hours following a surgery.…”

“…Of particular concern is the observation that the greatest risk of seizures is within the initial 48 hours following a surgery. 3,4 Depending on the type, extent, and various other factors associated with the surgical procedure, it is estimated that approximately 20 to 50% of patients will experience at least one seizure in the postoperative period. [3][4][5] This risk is further exacerbated if the patient has a history of preoperative seizures.…”

“…6 The consequences of postoperative seizures are a matter of serious concern, as they can lead to complications such as increased edema, neurological deficits, prolonged hospitalization, and, tragically, even death. 4,7 This increased risk of seizures is primarily attributed to the inflammatory and edematous responses generated during the surgical manipulation and any associated bleeding. Notably, edema typically becomes apparent within 24 to 48 hours after surgery, which also coincides with the period of the highest likelihood of seizure occurrences.…”

“…Of particular concern is the observation that the greatest risk of seizures is within the initial 48 hours following a surgery. 3 4…”