Intraoperative adverse events among surgeons in Singapore: a multicentre cross-sectional study on impact and support

BACKGROUND

It is known that many surgeons encounter intraoperative adverse events which can result in Second Victim Syndrome (SVS), with significant detriment to their emotional and physical health. There is, however, a paucity of Asian studies in this space. The present study thus aimed to explore the degree to which the experience of an adverse event is common among surgeons in Singapore, as well as its impact, and factors affecting their responses and perceived support systems.

METHODS

A self-administered survey was sent to surgeons at four large tertiary hospitals. The 42-item questionnaire used a systematic closed and open approach, to assess: Personal experience with intraoperative adverse events, emotional, psychological and physical impact of these events and perceived support systems.

RESULTS

The response rate was 57.5% (n = 196). Most respondents were male (54.8%), between 35 and 44 years old, and holding the senior consultant position. In the past 12 months alone, 68.9% recalled an adverse event. The emotional impact was significant, including sadness (63.1%), guilt (53.1%) and anxiety (45.4%). Speaking to colleagues was the most helpful support source (66.7%) and almost all surgeons did not receive counselling (93.3%), with the majority deeming it unnecessary (72.2%). Notably, 68.1% of the surgeons had positive takeaways, gaining new insight and improving vigilance towards errors. Both gender and surgeon experience did not affect the likelihood of errors and emotional impact, but more experienced surgeons were less likely to have positive takeaways (p = 0.035). Individuals may become advocates for patient safety, while simultaneously championing the cause of psychological support for others.

CONCLUSIONS

Intraoperative adverse events are prevalent and its emotional impact is significant, regardless of the surgeon's experience or gender. While colleagues and peer discussions are a pillar of support, healthcare institutions should do more to address the impact and ensuing consequences.

Study on weight loss outcomes after bariatric surgery to determine a metric least influenced by preoperative BMI

BACKGROUND

Percentage excess weight loss (%EWL) and percentage total weight loss (%TWL) are used for reporting outcomes after bariatric surgery. However, they are not ideal for comparing outcomes on populations of varied initial body mass index (BMI). This study aimed to validate a recently introduced metric - percentage alterable weight loss (%AWL), after laparoscopic sleeve gastrectomy (LSG) and Roux-en-Y gastric bypass (LRYGB).

METHODS

Analysis of weight data of all patients who had undergone LSG and LRYGB until the end of the year 2021. Outcomes for both procedures were analyzed separately. The patients were divided into quartile subgroups Q1 (lowest BMI) to Q4 (highest BMI) and weight loss up to 5 years postoperatively was compared using %EWL, %TWL and %AWL metrics. An intermediary metric was also tested for its effect on the weight loss patterns for both procedures.

RESULTS

The cohort included 1020 LSG and 322 LRYGB patients, with initial mean BMI of 43.5 ± 7.5 and 41.9 ± 8.3 kg/m2, respectively. %EWL significantly favors lower BMI subgroups for both procedures. %TWL is ideal for comparing weight loss during the first 6 months but it then favors higher BMI subgroups beyond 6 months. %AWL with reference BMI of 13 kg/m2 seems the best metric for medium-term comparison of weight loss for LRYGB and an intermediary metric based on BMI 8 kg/m2 provides the best fit for medium-term comparison for LSG.

CONCLUSIONS

%TWL is least influenced by initial BMI during short-term follow-up after LSG and LRYGB. For medium-term comparison, %AWL is best suited for LRYGB while an intermediary metric is found to provide the best fit for LSG.

Clinical audit of current Helicobacter pylori treatment outcomes in Singapore

INTRODUCTION

H. pylori eradication reduces the risk of gastric malignancies and peptic ulcer disease. First-line therapies include 14-day PAC (proton pump inhibitor [PPI], amoxicillin, clarithromycin) and PBMT (PPI, bismuth, metronidazole, tetracycline). Second-line therapies include 14-day PBMT and PAL (PPI, amoxicillin, levofloxacin). This clinical audit examined current treatment outcomes in Singapore.

METHODS

Clinical data of H. pylori-positive patients who underwent empirical first- and second-line eradication therapies from 1 January 2017 to 31 December 2018 were reviewed. Treatment success was determined by 13C urea breath test performed at least 4 weeks after treatment and 2 weeks off PPI.

RESULTS

A total of 963 patients (862 PAC, 36 PMC [PPI, metronidazole, clarithromycin], 18 PBMT, 13 PBAC [PAC with bismuth], 34 others) and 98 patients (62 PMBT, 15 PAL, 21 others) received first- and second-line therapies respectively. A 14-day treatment duration was appropriately prescribed for first- and second-line therapies in 65.2% and 82.7% of patients, respectively. First-line treatment success rates were noted for PAC (seven-day: 76.9%, ten-day: 88.3%, 14-day: 92.0%), PMC (seven-day: 0, ten-day: 75.0%, 14-day: 69.8%), PBMT (ten-day: 100%, 14-day: 87.5%) and PBAC (14-day: 100%). 14-day treatment was superior to seven-day treatment (90.8% vs. 71.4%; p = 0.028). PAC was superior to PMC (p < 0.001) but similar to PBMT (p = 0.518) and PBAC (p = 0.288) in 14-day therapies. 14-day second-line PAL and PBMT had similar efficacy (90.9% vs. 82.4%; p = 0.674).

CONCLUSION

First-line empirical treatment using PAC, PBMT and PBAC for 14 days had similar efficacy. Success rates for second-line PBMT and PAL were similar.

Improvement in quality of life and psychological symptoms after treatment for primary aldosteronism: Asian Cohort Study

BACKGROUND

In addition to increased cardiovascular risk, patients with primary aldosteronism (PA) also suffer from impaired health-related quality of life (HRQoL) and psychological symptoms. We assessed for changes in HRQoL and depressive symptoms in a cohort of Asian patients with PA, after surgical and medical therapy.

METHODS

Thirty-four patients with PA were prospectively recruited and completed questionnaires from 2017 to 2020. HRQoL was assessed using RAND-36 and EQ-5D-3L, and depressive symptoms were assessed using Beck Depression Inventory (BDI-II) at baseline, 6 months, and 1 year post-treatment.

RESULTS

At 1 year post-treatment, significant improvement was observed in both physical and mental summative scores of RAND-36, +3.65, P = 0.023, and +3.41, P = 0.033, respectively, as well as four subscale domains (physical functioning, bodily pain, role emotional, and mental health). Significant improvement was also seen in EQ-5D dimension of anxiety/depression at 1 year post-treatment. Patients treated with surgery (n = 21) had significant improvement in EQ-5D index score post-treatment and better EQ-5D outcomes compared to the medical group (n = 13) at 1 year post-treatment. 37.9, 41.6 and 58.6% of patients had symptoms in the cognitive, affective and somatic domains of BDI-II, respectively. There was a significant improvement in the affective domain of BDI-II at 1 year post-treatment.

CONCLUSION

Both surgical and medical therapy improve HRQoL and psychological symptoms in patients with PA, with surgery providing better outcomes. This highlights the importance of early diagnosis, accurate subtyping and appropriate treatment of PA.

Can venous base excess replace arterial base excess as a marker of early shock and a predictor of survival in trauma?

INTRODUCTION

Arterial base excess is an established marker of shock and predictor of survival in trauma patients. However, venous blood is more quickly and easily obtained. This study aimed to determine if venous base excess could replace arterial base excess as a marker in trauma patients at presentation and if venous base excess is predictive of survival at 24 hours and one week.

METHODS

This was a prospective study of 394 trauma patients presenting to the emergency department of a tertiary hospital over a 17-month period. Data on base excess at presentation, vital signs, shock index (SI), injury severity score (ISS), and mortality at 24 hours and one week was collected and analysed.

RESULTS

Arterial and venous blood gas tests were performed on 260 and 134 patients, respectively. Patients were stratified into groups based on their SI and ISS for analysis. There was no statistical difference between mean venous blood gas and arterial blood gas levels at presentation when SI > 0.7, regardless of ISS (p > 0.05). The mortality rate was 4.57%. Both venous and arterial base excess was lower in nonsurvivors compared to survivors (p < 0.05). However, at 24 hours and one week, the difference in base excess values at presentation between survivors and nonsurvivors was greater when using venous base excess compared to arterial base excess (11.53 vs. 4.28 and 11.41 vs. 2.66, respectively).

CONCLUSION

In conclusion, venous base excess can replace arterial base excess in trauma patients as a means of identifying and prognosticating early shock.

Para-oesophageal and parahiatal hernias in an Asian acute care tertiary hospital: an underappreciated surgical condition

INTRODUCTION

The prevalence of hiatal hernias and para-oesophageal hernias (PEHs) is lower in Asian populations than in Western populations. Progressive herniation can result in giant PEHs, which are associated with significant morbidity. This article presents the experience of an Asian acute care tertiary hospital in the management of giant PEH and parahiatal hernia.

METHODS

Surgical records dated between January 2003 and January 2013 from the Department of Surgery, Changi General Hospital, Singapore, were retrospectively reviewed.

RESULTS

Ten patients underwent surgical repair for giant PEH or parahiatal hernia during the study period. Open surgery was performed for four patients with giant PEH who presented emergently, while elective laparoscopic repair was performed for six patients with either giant PEH or parahiatal hernia (which were preoperatively diagnosed as PEH). Anterior 180° partial fundoplication was performed in eight patients, and mesh reinforcement was used in six patients. The electively repaired patients had minimal or no symptoms during presentation. Gastric volvulus was observed in five patients. There were no cases of mortality. The median follow-up duration was 16.3 months. There were no cases of mesh erosion, complaints of dysphagia or recurrence of PEH in all patients.

CONCLUSION

Giant PEH and parahiatal hernia are underdiagnosed in Asia. Most patients with giant PEH or parahiatal hernia are asymptomatic; they often present emergently or are incidentally diagnosed. Although surgical outcomes are favourable even with a delayed diagnosis, there should be greater emphasis on early diagnosis and elective repair of these hernias.

Transanal natural orifice specimen extraction in colorectal surgery: bacteriological and oncological concerns

INTRODUCTION

Natural orifice techniques have been developed to reduce incision-related morbidity in laparoscopic colorectal surgery. We describe our method of performing transanal specimen extraction in laparoscopic colorectal surgery, addressing bacteriological and oncological concerns in its implementation.

METHODS

Data of consecutive patients undergoing natural orifice specimen extraction (NOSE) laparoscopic colorectal surgery in our institution were retrospectively analysed. All specimens were extracted transanally via a wound protector, followed by intracorporeal end-to-end colorectal anastomosis. Perioperative details, microbiological and oncological findings were reviewed.

RESULTS

Between November 2014 and February 2015, five patients underwent NOSE laparoscopic colorectal procedures in our institution. All cases were completed laparoscopically and specimens were extracted transanally via a wound protector. There were no cases of post-operative anastomotic leaks, wound infections, intra-abdominal sepsis or faecal incontinence. Oncological margins and lymph node harvest were adequate for malignant cases. Transanal specimen extraction did not result in a malignant yield on peritoneal fluid cytology.

CONCLUSIONS

Early bacteriological, oncological and functional results show that NOSE is safe and feasible. Follow-up is required to establish that long-term oncological outcome is not compromised.

Laparoscopic mesh repair of parahiatal hernia: a case report

We report a case of a primary parahiatal hernia that was repaired laparoscopically with a composite mesh. A 51-year-old woman presented with vomiting and epigastric pain. CT scan showed a giant paraesophageal hernia with intrathoracic gastric volvulus. Intraoperatively, a diaphragmatic muscular defect was found lateral to an attenuated left crus of the diaphragm, distinct from the normal esophageal hiatus. The defect ring was fibrotic, making a tension-free primary repair difficult. A laparoscopic mesh repair was performed with a composite mesh, which was covered with the hernia sac to prevent potential erosion into the esophagus or stomach. Recovery was uneventful and the patient was discharged on the 5 days postoperatively. She remained asymptomatic at subsequent follow-up. Laparoscopic repair of parahiatal hernia can be safely performed. In circumstances where a large or fibrotic defect prevents a tension-free primary repair, the use of a composite mesh can provide effective repair of the hernia.

Rare cause of acute surgical abdomen with free intraperitoneal air: Spontaneous perforated pyometra. A report of 2 cases

BACKGROUND

The acute abdomen accounts for up to 40% of all emergency surgical hospital admissions and a large proportion are secondary to gastrointestinal perforation. Studies have shown the superiority of the abdominal CT over upright chest radiographs in demonstrating free intraperitoneal air. Spontaneous perforated pyometra is a rare cause of the surgical acute abdomen with free intraperitoneal air. Only 38 cases have been reported worldwide.

CASE REPORT

We report 2 cases of spontaneously perforated pyometra in our hospital's general surgery department. Both underwent exploratory laparotomy: one had a total hysterectomy and bilateral salpingo-oophorectomy, while the other had an evacuation of the uterine cavity, primary repair of uterine perforation and a peritoneal washout. A literature search was conducted and all reported cases reviewed in order to describe the clinical presentations and management of the condition. Of the 40 cases to date, including 2 of our cases, the most common presenting symptoms were abdominal pain (97.5%), fever (37.5%) and vomiting (25.0%). The main indication for exploratory laparotomy was pneumoperitoneum (97.5%).

CONCLUSIONS

Pyometra is an unusual but serious condition in elderly women presenting with an acute abdomen. A high index of suspicion is needed to make the appropriate diagnosis.

High frequency of polyoma BK virus shedding in the gastrointestinal tract after hematopoietic stem cell transplantation: a prospective and quantitative analysis

The polyoma BK virus (BKV) remains latent after primary infection and may reactivate during immunosuppression. The uroepithelium is the main latency site defined. This study addressed whether the gastrointestinal tract might be another latency site. To test this hypothesis, we prospectively quantified fecal BKV by quantitative PCR reaction in 40 patients undergoing hematopoietic SCT (HSCT). Urinary BKV was similarly quantified. Fecal BKV excretion was positive in 16/40 patients, of whom 10 were transient (<3 consecutively positive samples), six were persistent (⩾3 consecutively positive samples) and three were persistent with peaking (⩾10³-fold increase in viral load over baseline, reaching 5.11 × 10⁶, 4.68 × 10⁷ and 2.75 × 10⁸ copies/sample at 14, 14 and 21 days post-HSCT, respectively). Urinary BKV excretion was positive in 25/40 patients. Fecal BKV excretion was significantly correlated with that of the urine (P=0.036) and was significantly associated with allogeneic HSCT (P=0.037) and persistent and peaking of urinary BKV excretion (P<0.001). Binary logistic regression showed that BKV viruria was the only significant risk factor for fecal BKV excretion (P=0.021). Fecal BKV excretion occurred in 40% patients undergoing HSCT, implicating the gastrointestinal tract as a BKV latency site.

High frequency of polyoma BK virus shedding in the gastrointestinal tract after hematopoietic stem cell transplantation: a prospective and quantitative analysis

The polyoma BK virus (BKV) remains latent after primary infection and may reactivate during immunosuppression. The uroepithelium is the main latency site defined. This study addressed whether the gastrointestinal tract might be another latency site. To test this hypothesis, we prospectively quantified fecal BKV by quantitative PCR reaction in 40 patients undergoing hematopoietic SCT (HSCT). Urinary BKV was similarly quantified. Fecal BKV excretion was positive in 16/40 patients, of whom 10 were transient (<3 consecutively positive samples), six were persistent (> or =3 consecutively positive samples) and three were persistent with peaking (> or =10(3)-fold increase in viral load over baseline, reaching 5.11 x 10(6), 4.68 x 10(7) and 2.75 x 10(8) copies/sample at 14, 14 and 21 days post-HSCT, respectively). Urinary BKV excretion was positive in 25/40 patients. Fecal BKV excretion was significantly correlated with that of the urine (P=0.036) and was significantly associated with allogeneic HSCT (P=0.037) and persistent and peaking of urinary BKV excretion (P<0.001). Binary logistic regression showed that BKV viruria was the only significant risk factor for fecal BKV excretion (P=0.021). Fecal BKV excretion occurred in 40% patients undergoing HSCT, implicating the gastrointestinal tract as a BKV latency site.

Metabolic studies of turinabol in horses

Turinabol (4-chloro-17alpha-methyl-17beta-hydroxy-1,4-androstadien-3-one) is a synthetic oral anabolic androgenic steroid. As in the case of other anabolic steroids, it is a prohibited substance in equine sports. The metabolism of turinabol in human has been reported previously; however, little is known about its metabolic fate in horses. This paper describes the studies of both the in vitro and in vivo metabolism of turinabol in racehorses with an objective to identify the most appropriate target metabolites for detecting turinabol administration. For the in vitro studies, turinabol was incubated with fresh horse liver microsomes. Metabolites in the incubation mixture were isolated by liquid-liquid extraction and analysed by gas chromatography-mass spectrometry (GC-MS) after trimethylsilylation. The results showed that the major biotransformation of turinabol was hydroxylation at the C6, C16 and C20 sites to give metabolites 6beta-hydroxyturinabol (M1), 20-hydroxyturinabol (M2), two stereoisomers of 6beta,16-dihydroxyturinabol (M3a, M3b) and 6beta,20-dihydroxyturinabol (M4). The metabolite 6beta-hydroxyturinabol was confirmed using an authentic reference standard. The structures of all other turinabol metabolites were tentatively identified by mass spectral interpretation. For the in vivo studies, two horses were administered orally with turinabol. Pre- and post-administration urine samples were collected for analysis. Free and conjugated metabolites were isolated using solid-phase extraction and analysed by GC-MS as described for the in vitro studies. The results revealed that turinabol was extensively metabolised and the parent drug was not detected in urine. Two metabolites detected in the in vitro studies, namely 20-hydroxyturinabol and 6beta,20-dihydroxyturinabol, these were also detected in post-administration urine samples. In addition, 17-epi-turinabol (M5) and six other metabolites (M6a-M6c and M7a-M7c), derived from D-ring hydroxylation and A-ring reduction, were also detected. Except for 17-epi-turinabol, none of these metabolites has ever been reported in any species. All in vivo metabolites were detected within 48 h after administration.

Epigenetic inactivation of the CIP/KIP cell-cycle control pathway in acute leukemias

Dysregulation of the cell cycle is important in oncogenesis. We analyzed the potential inactivation of the CIP/KIP family of the cyclin E/CDK/RB pathway by gene promoter hypermethylation in leukemias. The methylation-specific polymerase chain reaction (MSP) with primers for methylated (M-MSP) and unmethylated (U-MSP) alleles of the p21, p27, and p57 genes was used to study five leukemic cell lines, 50 acute myeloid leukemia (AML) samples, and 25 acute lymphoblastic leukemia (ALL) samples. p21 was hemizygously methylated in Raji and Jurkat but remained unmethylated in U937, HL60, and NB4. p27 was hemizygously methylated in Raji but unmethylated in the other cell lines. p57 was completely methylated in Raji and NB4, hemizygously methylated in U937, and unmethylated in HL60 and Jurkat. At diagnosis, p21 methylation was not detected in any case of AML or ALL. p27 methylation occurred in 2 (4%) AML patients and in 1 (4%) ALL patient. p57 methylation occurred in 1 (2%) AML patient and in 1 (4%) ALL patient. Therefore, methylation inactivation of the INK4/CDK/RB pathway in leukemia is infrequent. A review of the literature showed a marked variation in the frequencies of methylation of these genes, which might be attributable to difference in methodologies used to detect gene methylation.

Absence of p300 gene promoter methylation in acute leukemia

p300 is a widely expressed transcriptional coactivator, and is involved in DNA repair, cell growth, differentiation, and apoptosis. Recent data suggest that it may function as a tumor suppressor. We investigated the frequency of aberrant methylation of p300 promoter in seven leukemic cell lines, as well as in the diagnostic samples of 46 patients with acute myelocytic leukemia (11 with M1, 22 with M2, 3 with M4, and 1 with M5), 24 patients with acute promyelocytic leukemia, and 22 patients with acute lymphoblastic leukemia (3 with T-cell, 1 with pre-B, 2 with Burkitt, 2 with early B-precursors, and 14 with common). None of the cell lines and patient samples showed p300 gene methylation. Therefore, hypermethylation of p300 is not an important mechanism in leukemogenesis.

Supplementary oxygen for elective Caesarean section under spinal anaesthesia: useful in prolonged uterine incision-to-delivery interval? †

BACKGROUND

The benefit of administering supplementary oxygen during elective Caesarean section under regional anaesthesia is controversial. It has been hypothesized that its use would improve fetal oxygenation in the event of a prolonged uterine incision-to-delivery (U-D) interval. Our aim was to test this hypothesis in a prospective, randomized, double-blinded, controlled study.

METHODS

We allocated randomly 204 women having elective Caesarean section under spinal anaesthesia to breathe 21, 40 or 60% oxygen. We recorded the U-D interval, umbilical arterial (UA) and venous (UV) blood gases and oxygen content and Apgar scores. Subgroup analysis was performed according to whether the U-D interval was prolonged (>180 s) or not.

RESULTS

The U-D interval was <180 s in 159 patients and >180 s in 45 patients. There were no differences in UV or UA blood gases, oxygen content or Apgar scores between cases with and without a prolonged U-D interval. In cases without a prolonged U-D interval, administering 60% oxygen increased UV PO(2) (mean 4.3 (SD 1.1) vs 3.7 (1.0) kPa, P=0.003) and oxygen content (14.4 (3.3) vs 12.9 (2.7) ml dl(-1), P=0.007) compared with air. In cases with a prolonged U-D interval, administering 60% oxygen increased UV PO(2) (4.6 (0.6) vs 3.9 (0.8) kPa, P=0.019) compared with air but there was no difference in UV oxygen content. There was no increase in the UV PO(2) or oxygen content when 40% oxygen was administered compared with air.

CONCLUSIONS

Supplementary oxygen did not increase fetal oxygenation in cases where the U-D interval was prolonged. Our data do not support the routine administration of supplementary oxygen during elective Caesarean section for this purpose.

Epigenetic dysregulation of the Jak/STAT pathway by frequent aberrant methylation of SHP1 but not SOCS1 in acute leukaemias

SOCS1 and SHP1 are negative regulators of the Jak/STAT signalling pathway that is implicated in leukaemogenesis. We studied if aberrant methylation of SOCS1 and SHP1 might be involved in the pathogenesis and prognostication of acute leukaemias by methylation-specific polymerase chain reaction (MSP). At diagnosis, methylation of SHP1 occurred more frequently in acute myeloid leukaemia (AML) (n=26, 52%) than acute lymphoblastic leukaemia (ALL) (n=6, 24%) (p=0.02). Methylation of SOCS1 was absent in both AML and ALL patients. SHP1 methylation was not associated with specific clinicopathologic features and had no prognostic impact on AML patients. Frequent methylation of SHP1, but not SOCS1, may be important in the pathogenesis, but not prognosis, of acute leukaemias.

Epigenetic inactivation of INK4/CDK/RB cell cycle pathway in acute leukemias

Dysregulation of cell cycle is important in oncogenesis. We analyzed the inactivation of the INK4 family CKI/CDK/RB pathway by gene promoter hypermethylation in leukemogenesis. The methylation-specific polymerase chain reaction (MSP) with primers for methylated (M-MSP) and unmethylated (U-MSP) alleles of the p15, p16, p18, and RB genes was used to study five leukemic cell lines, 50 acute myeloid leukemia (AML) and 25 acute lymphoblastic leukemia (ALL) samples. None of the leukemic cell lines showed p18 and RB methylation. p15 was methylated in Raji, while p16 was methylated in U937 and Raji. In NB4 and Jurkat, both alleles of p15 and p16 appeared to be deleted. At diagnosis, p15 methylation occurred in 29 (58%) AML patients, and 10 (40.0%) ALL patients. p16 methylation occurred in two (4%) AML and two (8%) ALL patients. Only one each of AML and ALL patients had concurrent p15 and p16 methylation. None of the patients had methylation of p18 or RB. In AML, p15 methylation was associated with M2 subtype ( p=0.018). Patients with and without p15 methylation had similar complete remission (CR) rates and projected 5-year overall survival (OS) or disease-free survival (DFS). Therefore, methylation inactivation of the INK4/CDK/RB pathway in leukemia involved primarily p15 and occasionally p16, but not p18 or RB. In AML, p15 gene methylation was associated with the M2 subtype, but was not prognostic for CR, OS, or DFS.

Infrequent hypermethylation of CEBPA promotor in acute myeloid leukaemia

The gene CEBPA, encoding the transcription factor C/EBPalpha, is crucial for granulocyte differentiation. We investigated the frequency of aberrant CEBPA promotor methylation with the methylation-specific polymerase chain reaction in 70 patients with acute myeloid leukaemia (AML). Two patients, both with M2 morphology, were found to have methylated CEBPA. In one of them, the fusion gene AML1/ETO, reported to cause transcription repression of CEBPA, was also present, suggesting that more than one mechanism might collaborate to suppress CEBPA gene expression. Aberrant CEBPA methylation is infrequent in AML, but may occur preferentially in the M2 phenotype.

Randomized, double-blind comparison of different inspired oxygen fractions during general anaesthesia for Caesarean section

BACKGROUND

The optimal inspired oxygen fraction FI(O(2)) for fetal oxygenation during general anaesthesia for Caesarean section is not known.

METHODS

We randomized patients having elective Caesarean section to receive one of the following: FI(O(2)) 0.3, FI(N(2))(O) 0.7 and end-tidal sevoflurane 0.6% (Group 30, n=20); FI(O(2)) 0.5, FI(N(2))(O) 0.5 and end-tidal sevoflurane 1.0% (Group 50, n=20), or FI(O(2)) 1.0 and end-tidal sevoflurane 2.0% (Group 100, n=20) until delivery. Neonatal outcome was compared biochemically and clinically.

RESULTS

At delivery, for umbilical venous blood, mean PO(2) was greater in Group 100 (7.6 (SD 3.7) kPa) compared with both Group 30 (4.0 (1.1) kPa, P<0.0001) and Group 50 (4.7 (0.9) kPa, P=0.002) and oxygen content was greater in Group 100 (17.2 (1.6) ml dl(-1)) compared with both Group 30 (12.8 (3.6) ml dl(-1), P=0.0001) and Group 50 (13.8 (2.6) ml dl(-1), P=0.0001). For umbilical arterial blood, PO(2) was greater in Group 100 (3.2 (0.4) kPa) compared with Group 30 (2.4 (0.7) kPa, P=0.003), and in Group 50 (2.9 (0.8) kPa) compared with Group 30 (2.4 (0.7) kPa, P=0.04); oxygen content was greater in Group 100 (10.8 (3.5) ml dl(-1)) than in Group 30 (7.0 (3.0) ml dl(-1), P<0.01). Apgar scores, neonatal neurologic and adaptive capacity scores, and maternal arterial plasma concentrations of epinephrine and norepinephrine before induction and at delivery were similar among groups. No patient reported intraoperative awareness.

CONCLUSIONS

Use of FI(O(2)) 1.0 during general anaesthesia for elective Caesarean section increased fetal oxygenation.