Sunil Rajan

Safety and efficacy of low molecular weight dextran (Dextran 40) in head and neck free flap reconstruction

BACKGROUND Antithrombotic agents have been used in microvascular surgeries. Low molecular weight dextran (dextran 40), though used, is not without complications. METHODS Retrospective analysis of 172 consecutive flaps. A comparison was made between two groups of patients (86 flaps each) with and without the use of dextran 40, in terms of safety and efficacy. RESULTS The free flap survival rate was 95.9%. The flap survival rates were comparable between the groups. Total flap loss in Group A (patients who received dextran 40) was 3.5% compared with 2.3% in Group B (patients who did not receive dextran 40) (p = 1.00). There was no statistically significant difference in the incidence of thrombotic flap complications between the groups. None of the patients developed acute respiratory distress syndrome or required prolonged ventilator support. No patient had dextran-related anaphylactoid reactions. Thirty-eight patients (43.7%) in Group A had postoperative atelectasis and 21 (25.6%) patients in Group B had this complication (p = 0.01). Six patients in Group A developed postoperative pneumonia, and five patients in Group B developed this complication (p = 0.93). CONCLUSIONS Though dextran 40 did not result in any significant adverse local or systemic complications, it is not useful as a postoperative antithrombotic agent in head and neck oncologic reconstruction with free tissue transfer.

Outcomes associated with stroke volume variation versus central venous pressure guided fluid replacements during major abdominal surgery.

Background and Aims: There is limited data on the impact of perioperative fluid therapy guided by dynamic preload variables like stroke volume variation (SVV) on outcomes after abdominal surgery. We studied the effect of SVV guided versus central venous pressure (CVP) guided perioperative fluid administration on outcomes after major abdominal surgery. Material and Methods: Sixty patients undergoing major abdominal surgeries were randomized into two equal groups in this prospective single blind randomized study. In the standard care group, the CVP was maintained at 10-12 mmHg while in the intervention group a SVV of 10% was achieved by the administration of fluids. The primary end-points were the length of Intensive Care Unit (ICU) and hospital stay. The secondary end points were intraoperative lactate, intravenous fluid use, requirement for inotropes, postoperative ventilation and return of bowel function. Results: The ICU stay was significantly shorter in the intervention group as compared to the control group (2.9 ± 1.15 vs. 5.4 ± 2.71 days). The length of hospital stay was also shorter in the intervention group, (9.9 ± 2.68 vs. 11.96 ± 5.15 days) though not statistically significant. The use of intraoperative fluids was significantly lower in the intervention group than the control group (7721.5 ± 4138.9 vs. 9216.33 ± 2821.38 ml). Other secondary outcomes were comparable between the two groups. Conclusion: Implementation of fluid replacement guided by a dynamic preload variable (SVV) versus conventional static variables (CVP) is associated with lesser postoperative ICU stay and reduced fluid requirements in major abdominal surgery.

Evaluation of endotracheal intubating conditions without the use of muscle relaxants following induction with propofol and sevoflurane in pediatric cleft lip and palate surgeries

Background and Aims: Children with facial clefts are usually difficult to intubate and it is considered safer to keep them spontaneously breathing while securing the airway. This prospective comparative study was conducted to evaluate endotracheal intubating conditions in pediatric patients undergoing cleft surgeries, without the use of muscle relaxants following induction with propofol and sevoflurane. Materials and Methods: Sixty patients aged 1month to 3 years, were randomly allocated into two equal groups. Anesthesia was induced with sevoflurane 8% in oxygen in group 1 and with propofol 3 mg/kg in group 2. Laryngoscopy and intubation were attempted 150 s after induction in both groups and ease of laryngoscopy, position of vocal cords, degree of coughing, jaw relaxation, and limb movements were assessed and scored. Total score of 5 was considered excellent, 6-10 good, 11-15 poor, and 16-20 bad. Total score ≤ 10 was considered clinically acceptable, and >10 as clinically unacceptable. Chi-square and Wilcoxon Mann-Whitney tests were used to analyze data. Results: There was no significant difference between groups when ease of laryngoscopy was compared. Sevoflurane induced patients had significantly better position of vocal cords at intubation and the propofol group had significantly more episodes of coughing. Significantly less number of patients had limb movements in sevoflurane group. There was no significant difference in degree of jaw relaxation between groups. The sevoflurane group had significantly better total scores and clinically acceptable intubating conditions. Conclusion: Sevoflurane 8% in oxygen provides clinically acceptable intubating conditions without use of muscle relaxants in pediatric cleft patients.

Are active warming measures required during paediatric cleft surgeries

Background: During paediatric cleft surgeries intraoperative heat loss is minimal and hence undertaking all possible precautions available to prevent hypothermia and use of active warming measures may result in development of hyperthermia. This study aims to determine whether there will be hyperthermia on active warming and hypothermia if no active warming measures are undertaken. The rate of intraoperative temperature changes with and without active warming was also noted. Methods: This study was conducted on 120 paediatric patients undergoing cleft lip and palate surgeries. In Group A, forced air warming at 38°C was started after induction. In Group B, no active warming was done. Body temperature was recorded every 30 min starting after induction until 180 min or end of surgery. Intragroup comparison of variables was done using Paired sample test and intergroup comparison using independent sample t-test. Results: In Group A, all intraoperative temperature readings were significantly higher than baseline. In Group B, there was a significant reduction in temperature at 30 and 60 min. Temperature at 90 min did not show any significant difference, but further readings were significantly higher. Maximum rise in temperature occurred in Group A between 120 and 150 min and maximum fall in temperature in Group B was seen during first 30 min. Conclusion: In pediatric cleft surgeries, we recommend active warming during the first 30 minutes if the surgery is expected to last for <2h, and no such measures are required if the expected duration is >2h.

Outcomes of implementation of enhanced goal directed therapy in high-risk patients undergoing abdominal surgery

Background and Aims: Advanced monitoring targeting haemodynamic and oxygenation variables can improve outcomes of surgery in high-risk patients. We aimed to assess the impact of goal directed therapy (GDT) targeting cardiac index (CI) and oxygen extraction ratio (O 2 ER) on outcomes of high-risk patients undergoing abdominal surgery. Methods: In a prospective randomised trial, forty patients (American Society of Anaesthesiologists II and III) undergoing major abdominal surgeries were randomised into two groups. In-Group A mean arterial pressure ≥ 65 mmHg, central venous pressure ≥ 8-10 mmHg, urine output ≥ 0.5 mL/kg/h and central venous oxygen saturation ≥ 70% were targeted intra-operatively and 12 h postoperatively. In-Group-B (enhanced GDT), in addition to the monitoring in-Group-A, CI ≥ 2.5 L/min/m 2 and O 2 ER ≤ 27% were targeted. The end-points were lactate levels and base deficit during and after surgery. The secondary end points were length of Intensive Care Unit (ICU) and hospital stay and postoperative complications. Wilcoxon Mann Whitney and Chi-square tests were used for statistical assessment. Results: Lactate levels postoperatively at 4 and 8 h were lower in-Group-B (P < 0.05). The mean base deficit at 3, 4, 5 and 6 h intra-operatively and postoperatively after 4, 8 and 12 h were lower in-Group-B (P < 0.05). There were no significant differences in ICU stay (2.10 ± 1.52 vs. 2.90 ± 2.51 days) or hospital stay (10.85 + 4.39 vs. 13.35 + 6.77 days) between Group A and B. Conclusions: Implementation of enhanced GDT targeting CI and OER was associated with improved tissue oxygenation.

Comparison of margin of safety following two different techniques of preoxygenation

Background and Aims: Shortening the duration of efficacious preoxygenation would provide benefit in emergency situations like fetal distress etc. This study aims to compare the margin of safety following preoxygenation using 8 vital capacity breaths (VCB) in 1 min and tidal volume breathing (TVB) for 3 min, by assessing changes in PaO2 and apnea induced desaturation time. Material and Methods: Patients were randomly divided into Group A and B. In Group A, 3 min of TVB using O2 flow of 5 l/min and in Group B, 8 VCB in 60 s using O2 flow of 10 l/min were used. Anesthesia was induced in all patients with propofol followed by succinylcholine 2 mg/kg intravenously. Mask ventilation was not done and following intubation endotracheal tube was kept open to atmosphere. The time taken for the patients to desaturate to 90% was noted and immediately ventilation was resumed. Arterial blood gas samples were taken while patients were breathing room air, immediately after preoxygenation and at 90% desaturation. Results: Baseline PaO2 of both the groups were comparable. After preoxygenation Group B had a significantly high PaO2 value than Group A (439.05 ± 62.20 vs. 345.16 ± 20.80). At 90% desaturation there was no significant difference between groups. Group B showed a significantly high apnea induced desaturation time when compared to Group A (6.87 ± 1.78 vs. 3.47 ± 0.38 min). Conclusions: Preoxygenation by 8 VCB in 1 min provides a greater margin of safety, as it results in a significantly high PaO2 with an almost doubled apnea induced desaturation time, in comparison with TVB for 3 min.

Effectiveness of single dose conivaptan for correction of hyponatraemia in post-operative patients following major head and neck surgeries

Background and Aims: Conivaptan, a vasopressin receptor antagonist, is commonly used for the treatment of euvolaemic, hypervolaemic hyponatraemia. Usually, an intravenous (IV) bolus followed by infusion is administered for many days. We decided to assess the effectiveness of single dose conivaptan for correction of hyponatraemia in post-operative patients. Methods: This was a prospective, randomised trial conducted in 40 symptomatic post-operative Intensive Care Unit (ICU) patients with a serum sodium level of ≤130 mEq/L. Group A patients received IV conivaptan 20 mg over 30 min, whereas in group B infusion of 3% hypertonic saline was started as an infusion at the rate of 20-30 ml/h. Serum sodium levels were measured at 12, 24, 48 and 72 h and the daily fluid balance was measured for 3 days. The Chi-square test, Wilcoxon signed rank test and Mann-Whitney tests were used as applicable. Results: The serum sodium levels before initiating treatment were comparable between groups. However, subsequent sodium levels at 12, 24 and 48 h showed significantly high values in group A. Though at 72 h the mean sodium value was high in group A, it was not statistically significant. Group A showed a significantly high fluid loss on day 1, 2 and 3. The mean volume of hypertonic saline required in group B showed a steady decline from day 1 to 3 and only 13 patients required hypertonic saline on the 3 rd day. Conclusion: Single dose conivaptan is effective in increasing serum sodium levels in post-operative ICU patients up to 72 h associated with a significant negative fluid balance.

Effect of pre-operative discontinuation of angiotensin-converting enzyme inhibitors or angiotensin II receptor antagonists on intra-operative arterial pressures after induction of general anesthesia.

Context: Medical guidelines advise perioperative continuation many antihypertensives, but discontinuing angiotensin antagonists before surgery. Aims: This study is aimed to determine the effect of preoperative discontinuation of angiotensin-converting enzyme inhibitors (ACEI) or angiotensin II receptor antagonists (ARA) on intra-operative blood pressure after induction of general anesthesia. Settings and Design: The study was a randomized, prospective and double blinded one done in 60 hypertensive patients, receiving these drugs. Materials and Methods: Patients were randomized into two equal groups. In Group A, ACEI or angiotensin II receptor antagonist was stopped the day before surgery, but in Group B it was continued. Anesthetic management was standardized by a study protocol. Systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP) were measured just before induction and after induction at 1 min, 3, 5, 10, 15, 30, 45 and 60 min. Statistical Analysis: Difference between means and difference between two proportions was analyzed using Normal test for means and corresponding P values were calculated. Results: Pre-induction SBP, DBP and MAP were comparable between groups. However when the pre-induction values were compared with subsequent readings at 3, 5, 10, 15, 30, 45 and 60 min, it was found that there was a significant reduction in SBP, DBP and MAP in Group B up to 60 min. Conclusions: Intraoperative hemodynamics can be safely managed when ACEI or ARA are withheld on the day of surgery.

A comparison of effects of oral premedication with clonidine and metoprolol on intraoperative hemodynamics and surgical conditions during functional endoscopic sinus surgery.

Context: Establishing a near perfect surgical field during functional endoscopic sinus surgery (FESS) is essential and even a minor bleeding can severely compromise an already restricted view. So, if controlled hypotension can be provided without compromising the safety of patient by a relatively effortless method, surgical field can be improved greatly. Aims: The aim of this study was to compare the hemodynamic changes and surgical conditions during FESS following oral premedication with clonidine and metoprolol. Settings and Design: A total of 40 patients undergoing FESS were included in this prospective, randomized controlled study. Subjects and Methods: Patients were divided into two equal groups. Group A patients were premedicated with oral clonidine 300 mcg and Group B with oral metoprolol 50 mg, 2 h before surgery. All patients received fentanyl 2 mcg/kg and induced with propofol 2 mg/kg. Intubation was done following vecuronium 1 mg/kg. Anesthesia was maintained with 66% N2O, 33% O2 and 1% isoflurane. The heart rate (HR) and blood pressure (BP) were measured before induction and thereafter every 15 min up to 2 h. The surgeons were asked to estimate the quality of the operative field using a pre-defined category scale with scores 1-5. Statistical Analysis: Difference within the groups was analyzed using analysis of variance and post-hoc test was used to test the difference between individual groups. Chi-square test was used to find out the association between categorical variables. Results: Comparison of category scale revealed a lower score in Group A up to 60 min. Group B patients showed a statistically lower HR from pre-induction up to 90 min while systolic BP (SBP), diastolic BP (DBP) and mean arterial pressure did not show a significant difference. Conclusions: Oral premedication with 300 mcg of clonidine produced a better operative field than oral metoprolol 50 mg during FESS.

Effectiveness of transnasal humidified rapid-insufflation ventilatory exchange versus traditional preoxygenation followed by apnoeic oxygenation in delaying desaturation during apnoea: A preliminary study

Background and Aims: Transnasal humidified rapid-insufflation ventilatory exchange (THRIVE) during apnoea has shown to delay desaturation. The primary objective was to compare time to desaturate to <90% during apnoea with THRIVE versus traditional preoxygenation followed by apnoeic oxygenation. Methods: This prospective, randomised, single-blinded study was conducted in 10 adult patients presenting for direct laryngoscopy under general anaesthesia without endotracheal intubation. Group P patients were preoxygenated with 100% oxygen, and in Group H, high-flow humidified oxygen was delivered using nasal cannula for 3 min. After induction and neuromuscular blockade, time to desaturate to 90%, while receiving apnoeic oxygenation, was noted. Chi-square test and Mann–Whitney tests were used. Results: Group H had a significantly longer apnoea time as compared to Group P (796.00 ± 43.36 vs. 444.00 ± 52.56 s). All patients in Group H continued to have nearly 100% saturation even at 12 min of apnoea. However, in Group P, 80% of patients desaturated to <90% after 6 min of apnoea. Baseline blood gases, that following preoxygenation and at 3 min of apnoea time were comparable in both groups. At 6 min, Group H had a significantly higher PaO2 (295.20 ± 122.26 vs. 135.00 ± 116.78) and PaCO2 (69.46 ± 7.15 vs. 59.00 ± 4.64). Group H continued to have a PaO2of >200 mmHg even at 12 min of apnoea with a significant rise in PaCO2along with fall in pH after 6 min. Conclusion: During apnoeic periods time to desaturate to <90% was significantly prolonged with use of THRIVE.