Pain and vomiting are the most common and poignant symptoms which follow surgery under general anesthesia1. Sometimes nausea and vomiting may be more distressing affecting patient recovery, increasing postoperative complications, and delaying the hospital discharge2.PONV can result in serious complications like raised intra cranial pressure in craniotomy patients3. The incidence of postoperative emesis in some large studies has been reported to be 20–30 %4.The incidence is evenhigher (60%) in neurosurgical patients.5 The patho-physiology of postoperative nausea and vomiting is very complex.6 Separate processes for the development of nausea and vomiting are involved7. Nausea occurs due to a forebrain pathway, whereas vomiting arises from central pattern generator in the hindbrain.An emetic center placed in the medulla is activated by different stimuli.
Mortality and morbidity from PONV have
markedly decreased in recent years because of
improved general anesthesia drugs, early recognition
of risk factors, and availability of better
antiemetic drugs. Ondansetron is a potent antiemetic
drug in the prevention and treatment of
PONV in emergency craniotomy under general
anesthesia in head trauma patients.
The gastrointestinal tract, chemoreceptor trigger zone, higher cerebral cortex, cerebellum, and vestibular apparatus receive signals from this area. In particular, the postrema area in the fourth ventricle lies outside the blood-brain barrier and is thus exposed to effects of different medication. In the development of nausea and vomiting, variety of receptors are engaged.These are serotonergic, cholinergic, dopaminergic, histaminic, opioid, acetylcholine, 5-hydroxytryptamine-3 receptors, and neurokinin-1 receptors. The above receptors are linked to the emetic center. So these differing stimuli imply that combination therapy would be more useful to reduce PONV8,9 Four strong risk factors associated with PONV are suggested by Apfel. Female gender, previous history of motion sickness and/or nausea and vomiting, non-smoker, and treatment with postoperative opioids are these variables. He indicated that each factor increases 20 percent risk of PONV.10 A fifth risk factor, duration of surgery> 1 hour is identified by Koivuranta et al.11 Other risk factors include use of inhalational anesthetics, nitrous oxide and duration of anesthesia.12 Variants of 5-Hydroxytrypthamine receptor genes are also associated with increased incidence of PONV.13,14 Various medications are used in the management of PONV but for the ultimate control or treatment of PONV, there is no specific drug or tool. Pharmacological agents and non-pharmacological measures are used in the treatment of PONV.15,16 Antiemetics are the mainstay of treatment for PONV.17,18 Anti-cholinergic, anti-dopaminergic, anti-histamine, and anti-serotonergic are the major pharmacological classes of antiemetics.19 In addition to this, dexamethasone is often found to be a successful antiemetic.20 Serotonin (5-HT3) antagonists are the most common and effective anti-emetics.21 These drugs peripherally block gut vagal afferents and act centrally in the area postrema.22 The most commonly used 5-HT3 antagonist is ondansetron. Other 5-HT3 antagonists include granisetron, tropisetron, ramosetron, and palonosetron. Non-pharmacological maneuvers include acupuncture, acupoint stimulation, and transcutaneous electrical nerve stimulation (TENS). It results in a decrease in the incidence of PONV.23
MATERIALS AND METHODS
It was a prospectively conducted cross-sectional study, hospital-based and carried in the departments of anesthesia and Neurosurgery, Naseer Teaching Hospital and Lady Reading Hospital, Peshawar. It was a study of nine months duration from June 2019 to March 2020, and was conducted on 131 patients of head trauma, who underwent emergency craniotomy under GA. Only forty-four(44) patients were selected. Only 4 developed postoperative nausea and vomiting. A simple non-probability consecutive sampling technique was applied in this study.
Inclusion criteria All head trauma patients, aged 18 to 60 years of both genders and only those patients who develop PONV were included in the study.
Exclusion criteria The poly-trauma patients, patients not requiring craniotomy in an emergency, patients with a previous history of chronic nausea and vomiting, and patients who needed ICU admission were excluded from the study. Complete control of nausea and vomiting with a single drug was undertaken. While a second drug was required in combination with the first drug. Patients admitted in the Neurosurgery Department of Naseer Teaching Hospital and Hayatabad Medical Complex, Peshawar were selected who fulfilled inclusion criteria after getting permission from ethical committees of concerned hospitals. Informed consents were taken from patients or attendants of patients and all information was put in pre-designed proforma. Diagnosis of head injury was made based on clinical history, physical examination, and CT brain. All the patients were operated under GA in the supine position. Isoflurane was used for induction and maintenance anesthesia. As a muscle relaxant, atracurium at 0.5 mg/kg body weight was given. For pain control during GA, opioids were avoided and ketorolac @ 0.5mg/kg was used. Thepatients were kept in the ward after surgery. All patients were given ondansetron 8 mg as they develop nausea and vomiting. The data were analyzed using the statistical program SPSS version 22. For quantitative variables like age, mean/standard deviation was used. Frequency/percentage were calculated for categorical variables like gender, type of head injury, and effectiveness/ineffectiveness of antiemetic drugs. All the results were presented in the form of tables and charts or graphs.
One hundred and thirty one (131) patients of head trauma were included who underwent craniotomy under GA. Only forty-four (33.6%) patients were observed to develop nausea and vomiting. Among these patients, twelve (27.3%) were males and thirty-two (72.7%) were females with male to female ratio of 1:2.6. All these patients were given ondansetron intravenously. In thirty- nine (88.6%) patients, PONV was completely controlled and treated with ondansetron, and only five (11.4%) patients required other antiemetic drugs in combination with ondansetron for complete remedy.
This study showed a relatively higher incidence of PONV (33%) which may be attributed to head injuries. This is supported by other studies on PONV in head injuries. Even some other studies showed that incidence of PONV is much higher in head injuries cases. Meng L. and Quinlan JJ described that PONV occurs in six out of ten patients who underwent retromastoid craniotomy with microvascular decompression of cranial nerves24. Our study has low incidence of PONV compared to that of Meng L. and Quinlan JJ. This may be due to the exclusion of high risk cases like those with prior history of PONV or motion sickness from our study.25 It also showed the higher incidence of PONV in females which endorses other studies as our study showed a male to female ratio of 1: 2.7. Ondansetron has shown promising results in these cases as eight out of ten patients were recovered after single use of ondansetron. Many large-scale studies have indicated that preventive administration of ondansetron decreases PONV by 25%. Although, this study has shown a very promising result to treat PONV but it cannot be compared with the randomized control trials. In one such study, NK1 antagonist, aprepitant was found superior to ondansetron in control of vomiting.26 Another study showed that combination of dexamethasone-dimenhydrinate are better than dexamethasone-ondansetron to control PONV.27 Often, a single antiemetic agent is not effective in prevention and treatment of PONV, so multimodal approach is found to be useful in treating and managing high risk patients. In our study we gave injection dexamethasone 0.1 mg/ kg in resistant cases (n=5) as rescue drug and their PONV was completely controlled. Further studies are suggested regarding combination of antiemetics for control of PONV. Also, a simplified algorithmic approach for such cases makes PONV incidence significantly low28.
PONV can cause serious and deleterious complications in post-operative and neurosurgical patients. Sometimes the use of a single antiemetic drug may not prevent or treat nausea and vomiting and a combination of drugs should be used. In neurosurgical patients, the antiemetic agents causing sedation should be avoided. This study suggests that due to better results and minimal complications in post-operative craniotomies, ondansetron should be used as first line drug in the treatment of PONV.