Second infant spinal anesthetic: Incidence, dose modification, and adverse events after initial failure.

INTRODUCTION: Infant spinal anesthesia is an important technique in premature and ex-premature infants undergoing lower abdominal surgery. Previous studies of infant spinal anesthesia report high failure rates, but fail to adequately identify contributing factors. The aim of this study is to retrospectively review spinal anesthetics from a quaternary anesthetic centre to determine overall spinal failure rate, incidence of second spinal attempts and adverse events associated with a second spinal anesthetic. METHODS: A retrospective review of infant spinal anesthetics performed between May 2016 and June 2023. RESULTS: Five hundred and fifty-one infants (mean postmenstrual age 42.9 weeks and weight 3873 g) were included. The overall success rate on first attempt was 86.5% with a further 5.1% requiring a successful second spinal anesthetic after initial failure. Spinal anesthetic failure requiring conversion to general anesthesia occurred in 9.4% of cases The causes of failed spinal anesthetic were inability to access the subdural space (dry tap 4.2%), inadequate motor blockade (2.9%), and repeated bloody taps (2.2%). Spinal anesthetic failure was significantly increased in cases where the anesthetist was routinely performing less than 5 spinal anesthetics per year [OR 2.21 (95% CI 1.28, 3.83, p = .004)] but only weakly associated with years of pediatric anesthetic experience. Failure rates were 21.4% with styletted spinal needles and 9.2% for non styletted [OR 2.68 (95% CI 1.23-5.86, p = .012)]. The incidence of perioperative apnoea was 6.7% with the highest rate in infants in which failed spinal anesthesia required conversion to general anesthesia (25%). There were 28 cases where initial spinal anesthetic failed to produce adequate anesthesia and a repeat spinal anesthetic was performed. Repeat spinal anesthesia was successful in 92.8% of cases with awake caudal anesthesia successful in 7.2% of cases. In three cases high spinal blockade occurred, one after a single spinal and two after a repeat spinal. Both repeat spinal high block cases required intubation and brief resuscitation. CONCLUSION: Infant spinal anesthesia is associated with high success rates if experienced anesthetists are present or performing the block. Repeat spinal anesthesia may be associated with an increased incidence of high spinal block. Greater awareness of the slow onset of high block should promote techniques aimed at minimizing cephalad spread of local anesthetic including slight head up positioning during surgery.

Performance of the BBraun perfusor space syringe driver under hyperbaric conditions.

BACKGROUND: The BBraun Perfusor Space™ syringe driver is already in use by ambulance services and retrieval teams but has not previously been assessed for hyperbaric chamber use. METHODS: Pump flow accuracy was tested at rates between 1 and 40 ml· h⁻¹ using three different brands of 50 ml syringe. Function of the occlusion alarms was assessed using the same syringes. The hyperbaric profile involved pressurisation to 284 kPa at 30 kPa· min⁻¹, 30 min at 284 kPa and decompression at 30 kPa· min⁻¹. Output was recorded from differences in weight of collection containers. A single device was tested. RESULTS: Performance was highly dependent on the syringe type used, with two of the three 50 ml syringes used demonstrating 'stiction' at both low and high occlusion pressure alarm settings, most marked during pressurisation. On decompression from 284 kPa all syringes alarmed at significantly lower pressures. Because of the stiction problems only the flow measurements for the BBrown Omni¬ x 50 ml syringes are reported. At a pressure of 284 kPa, the difference between programmed and delivered rates was within the manufacturer's specification of 10%: at 40 ml· h⁻¹ (median variation 1.25%, IQR 0.5-1.7%), 10 ml· h⁻¹ (8.6%, IQR 8-9.2%), 5 ml· h⁻¹ (-8.8%, IQR - 1.6-8.8%) and 1 ml· h⁻¹ (-4%, IQR 4-12%). Pressurisation was associated with significantly lower flow rates whilst decompression was associated with significantly increased rates. Limited testing at 405 kPa was also within the manufacturer's specifications. CONCLUSION: A BBraun Infusor Space syringe driver performed within acceptable performance criteria but is highly dependent on syringe type and flow rates. The potential for the device to under deliver on pressurisation and over deliver on depressurisation, however, suggests vigilance and appropriate rate adjustments may be necessary during these phases.

Iatrogenic cerebral gas embolism: analysis of the presentation, management and outcomes of patients referred to The Alfred Hospital Hyperbaric Unit.

INTRODUCTION: The aim of this study was to review patients with iatrogenic cerebral gas embolism (CGE) referred to The Alfred Hospital hyperbaric unit to determine whether hyperbaric oxygen treatment (HBOT) reduced morbidity and mortality. METHODS: This is a retrospective cohort study with a contemporaneous comparison group of patients referred between January 1998 and December 2014. The primary end point was good neurological outcome at the time of discharge from hospital or rehabilitation facility as assessed by the Glasgow Outcome Scale (GOS-E). RESULTS: Thirty-six patients were treated with HBOT for CGE and nine patients were diagnosed with CGE but did not receive HBOT. Thirty-two patients developed CGE from an arterial source and 13 from a venous source. The mean time from recognition of the event to institution of HBOT was 15 hours. Four of 45 patients (8.9%) died. Good neurological outcomes (defined as GOS-E 7 or 8) occurred in 27 patients and moderate disability in 13. The only independent factor that was associated with good neurological outcome was time to first HBOT (OR 0.94, 0.89-0.99; P = 0.05). Hemiplegia as the first presenting sign, however, was associated with poor outcome (OR 0.27, 0.06-1.08; P = 0.05). The source of embolus (arterial versus venous), hyperbaric treatment table used and patient age did not affect outcome. CONCLUSION: Appropriate treatment of CGE with hyperbaric oxygen was found to be impeded by delays in diagnosis and subsequent transfer of patients. Better neurological outcome was associated with HBOT within eight hours of CGE.

Hyperbaric oxygen in the treatment of calciphylaxis: A case series and literature review.

AIMS: Calcific uraemic arteriolopathy (CUA) or calciphylaxis is most commonly seen in end-stage renal disease and is associated with significant morbidity and mortality. The aim of this study was to determine whether hyperbaric oxygen therapy (HBOT) is effective in healing calciphylaxis lesions and to determine if there are any patient factors that can predict wound healing and patient survival. METHODS: We identified by retrospective review all cases of CUA referred to our institution for treatment with HBOT. We documented the clinical and biochemical parameters of this patient population, the size and distribution of the lesions as well as wound outcomes and patient survival following treatment. RESULTS: A total 46 patients were identified with CUA associated with renal failure. Of the 46 patients, only 34 received a full course of HBOT. The balance was deemed unsuitable for treatment or was unable to tolerate treatment and was palliated. Of the 34 patients that received a full course of HBOT, 58% showed improvement in their wound scores, with more than half of these patients having complete healing of their wounds. The balance did not benefit from the therapy and had a very poor prognosis. Those that benefited from HBOT survived on average for more than 3 years. The only factor significantly associated with improved wound healing and survival was diabetes. CONCLUSION: This retrospective analysis suggests a role for HBOT in the treatment of CUA with more than half of the treated patients benefiting and surviving for an average of more than 3 years.

Pediatric hyperbaric oxygen therapy in Victoria, 1998-2010.

OBJECTIVES: The aim of this review is to identify clinical conditions currently treated in a pediatric population referred to the Alfred hyperbaric unit, to describe outcomes, and detail any complications occurring during treatment or transfer between units. DESIGN: Retrospective, noncontrolled, clinical study. SETTING: Adult hyperbaric unit in a university hospital. PATIENTS: Children aged <16 yrs referred for hyperbaric oxygen therapy between January 1998 and December 2010. INTERVENTIONS: Hyperbaric oxygen therapy at pressures from 2.0 to 3.0 atmospheres absolute. MEASUREMENTS AND MAIN RESULTS: Fifty-four patients with a median age at presentation of 15 yrs (range, 0.25-16 yrs) received 668 treatment sessions (mean, 12.4; 95% confidence interval, 9.2-15.5). Fourteen patients were identified as having successfully completed treatment while managed in intensive care units. There were 44 events in 668 treatments (6.6%) in the pediatric group and 12 events in 126 treatments (9.6%) in the pediatric intensive care unit group. There were two oxygen toxicity convulsion (0.3%), two episodes of progressive hypoxemia (0.3%), and four episodes of brief hypotension (0.6%). CONCLUSIONS: Provision of hyperbaric oxygen to children with significant illness is feasible and associated with a low risk of complications. The most difficult aspect of managing pediatric hyperbaric oxygen therapy is in the coordination of the treatment with ongoing surgical and intensive care management. The lack of pediatric staff and facilities in major hyperbaric units necessitates multiple transfers for appropriate treatment.