Personalization of pulse arrival time based blood pressure surrogates through single spot check measurements.

OBJECTIVE: We investigate the effect of selective single parameter personalization on the performance of multi-parameter models for pulse arrival time (PAT) based blood pressure (BP) surrogates. METHODS: Our data set stems from 15 surgery patients, and we selected from each patient 5 segments of 30 min length each. We evaluate the root mean squared BP tracking error of the two models with and without single parameter personalization. We further compare the BP tracking performance to a surrogate-free sample-and-hold approach, e.g., as afforded by conventional non-invasive blood pressure (NIBP) oscillometry. RESULTS: Parameter personalization is key to realizing a tracking performance benefit of PAT-based BP surrogates. The highest tracking error reduction of about 3.7 mmHg with respect to a sample-and-hold approach was reached with a personalized model which is linear in the pulse wave velocity domain. It achieves an estimation error of 7.8 mmHg with respect to a continuously measured invasive reference.Clinical Relevance-We give a performance analysis of PAT-based BP surrogates which are personalized to a patient with a single NIBP spot measurement. We show for surgery patients that patient-specific personalization enables continuous beat-to-beat BP monitoring over 30 min intervals with a average root mean squared error of less than 8 mmHg.

Optimized non-uniform sampling of blood pressure time series from the operating room.

OBJECTIVE: We investigate an optimized non-uniform sampling strategy for blood pressure time series from the operating room (OR). Our aim is to obtain an approximate bound on the achievable reconstruction fidelity given an average sampling rate constraint. METHODS: Our data set consists of 117 hours of recordings of continuous invasive blood pressure from 28 surgery patients. We evaluate the root mean squared error (RMSE) of the zero-order hold sampling reconstruction of the blood pressure time series. We quantitatively compare the errors achieved by uniform versus optimized non-uniform sample placements for several average sample rates, ranging from 2 to 24 measurements per hour. RESULTS: An optimized non-uniform measurement schedule can lead to approximately 50% reduction of reconstruction RMSE for systolic, mean, and diastolic blood pressure time series with respect to uniform sampling, while maintaining the same average sampling rate.

Video assisted thoracoscopic surgery (VATS) for pneumothorax: a reason for unscheduled surgery?

Timing of urgent surgery, with full schedules and the businesslike attitude of operating room management, can lead to animated discussions, affecting quality of care and job satisfaction. No publication appears to address the timing of definitive care for a stable, spontaneous, pneumothorax (SP) by unscheduled, or urgent, video assisted thoracoscopic surgery (VATS). We reviewed the literature and describe our series of 38 patients with SP and VATS. Of 185 patients with SP, 38 were presented for VATS. Of these 29% were unscheduled. Average time between diagnosis of SP and VATS was 11 days, with four days between decision for VATS and its execution. Post-operative antibiotics were prescribed to 37% of patients. There was a correlation between chest drain time in situ and infective signs (p = 0.001, rho = 0.654) as well as proven infections (p = 0.05, rho = 0.386), but not between for scheduled and unscheduled procedures. In conclusion, our case series and review did not identify reasons why VATS for SP should be performed as an urgent procedure, though we support more rapid planning.

Laparoscopic vs. small incision cholecystectomy: Implications for pulmonary function and pain. A randomized clinical trial.

BACKGROUND: Upper abdominal surgery, including laparoscopic cholecystectomy (LC), is associated with post-operative pulmonary dysfunction. LC has, by consensus, become the treatment of choice for symptomatic cholecystolithiasis. The small-incision cholecystectomy (SIC), a procedure which does not require a pneumoperitoneum threatens to be lost to clinical practice even though there is evidence of equality. We hypothesized that the SIC technique should be equal and might even be superior to the LC when considering post-operative pulmonary function due to the short incision length. METHODS: A single-centre, randomized clinical trial was performed including patients scheduled for elective cholecystectomy. Pulmonary flow-volume curves were measured pre-operatively, post-operatively, and at follow up. Blood gas analyses were measured pre-operative, in the recovery phase and on post-operative day 1. Anaesthesia, analgesics, and peri-operative care were standardized by protocol. Post-operatively, patients and caregivers were blinded to the procedure. RESULTS: A total of 257 patients were analysed. There was one pulmonary complication (pneumonia) in the LC group. In both groups, similar reductions of approximately 20% in pulmonary function parameters occurred, with complete recovery to pre-operative values. Patients in the SIC group consumed more analgesia when compared with the LC group without impact on blood gas analysis. Patients converted to a conventional open technique showed significant differences in six of the eight parameters in pulmonary function tests. CONCLUSION: When evaluated with strict methodology and standardization of care, no clinically relevant differences were found between SIC and LC regarding pulmonary function. Our results suggest that the popularity of the laparoscopic technique cannot be attributed to pulmonary preservation.

Anaesthesiological considerations in small-incision and laparoscopic cholecystectomy in symptomatic cholecystolithiasis: implications for pulmonary function. A randomized clinical trial.

BACKGROUND: Upper abdominal surgery, including laparoscopic cholecystectomy (LC), is associated with post-operative pulmonary dysfunction. LC has, by consensus, become the treatment of choice for symptomatic cholecystolithiasis. Small-incision cholecystectomy (SIC), a procedure that does not require a pneumoperitoneum, threatens to be lost to clinical practice, even though there is evidence of equality. We hypothesized that the SIC technique should be equal, and might even be superior, to LC when considering post-operative pulmonary function because of the short incision length. METHODS: A single-centre randomized clinical trial was performed including patients scheduled for elective cholecystectomy. Pulmonary flow-volume curves were measured pre-operatively, post-operatively and at follow-up. Blood gas analyses were measured pre-operatively, in the recovery phase and on post-operative day 1. Anaesthesia, analgesics and peri-operative care were standardized by protocol. Post-operatively, patients and caregivers were blind to the procedure. RESULTS: Two hundred and fifty-seven patients were analysed. There was one pulmonary complication (pneumonia) in the LC group. In both groups, similar reductions of approximately 20% in pulmonary function parameters occurred, with complete recovery to pre-operative values. Patients in the SIC group consumed more analgesia when compared with the LC group, without any impact on blood gas analysis. Patients converted to a conventional open technique showed significant differences in six of the eight parameters in pulmonary function tests. CONCLUSION: When evaluated with strict methodology and standardization of care, no clinically relevant differences were found between SIC and LC with regard to pulmonary function. Our results suggest that the popularity of the laparoscopic technique cannot be attributed to pulmonary preservation.

Airway management by first responders when using a bag-valve device and two oxygen-driven resuscitators in 104 patients.

BACKGROUND AND OBJECTIVE: To evaluate the capability of first responders to ensure an airway and ventilate the lungs of a patient employing a bag-valve device and two oxygen-driven resuscitators. METHODS: Prospective, controlled, blinded, single-centre clinical trial using a bag-valve device and one of two FR-300 devices, with 20 cmH2O working pressure, flows of 24 and 30 L min(-1). One-hundred-and-four patients were analysed. Induction of anaesthesia was followed by ventilation of the lungs with a bag-valve device and an Oxylator (CPR Medical Devices Corp., Markham, Ontario, Canada) in manual and automatic modes. Each series was repeated twice by a fireman first responder using a hand-held mask to seal the airway, once under anaesthesia and then again under anaesthesia with muscle relaxation. RESULTS: Patients' mean age 49 +/- 17 yr; 47% male, 48-132 kg. Only 29% had optimal facial and airway physiognomy. Airway management was significantly poorer when the bag-valve device was used than with either Oxylator mode (P < 0.0001); 23% of cases were not manageable with the bag-valve device. Gastric insufflation was markedly less with the Oxylator (P < 0.02). CONCLUSIONS: The use of an oxygen-driven device improves the ability of first responders to secure an airway and reduce gastric insufflation, even when distracted. Oxylators perform significantly better (P < 0.0001) than the bag-valve device.

Can first responders achieve and maintain normocapnia when sequentially ventilating with a bag-valve device and two oxygen-driven resuscitators? A controlled clinical trial in 104 patients.

BACKGROUND AND OBJECTIVE: To evaluate the capability of first responders to achieve and maintain normal ventilation of the lungs of victims employing a bag-valve device and two oxygen-driven resuscitators. METHODS: Prospective, controlled, blinded, single-centre clinical trial using a bag-valve device and one of two FR-300 devices, with 20 cmH2O working pressure, and flows of either 24 or 30 L min(-1). One hundred and four patients were analysed. Induction of anaesthesia followed by ventilation of the lungs with a bag-valve device and an Oxylator in manual and automatic modes performed by a fireman first responder. Each series was repeated for three conditions (anaesthesia; anaesthesia plus muscle relaxation, both with facemask; anaesthesia plus relaxation using an endotracheal tube). RESULTS: Patients age 49 +/- 17 yr; 47% males, 48-132 kg. Normocapnia was achieved and maintained in 66% (bag-valve device), 82% (Oxylator). CONCLUSIONS: The use of an oxygen-driven device improves the ability of first responders to achieve and maintain normocapnia even when distracted. Use of the Oxylators improves performance (P < 0.001) vs. the bag-valve device significantly.

Training needs and qualifications of anaesthesiologists not exposed to ALS.

OBJECTIVES: To establish which needs exist for specific training in Advanced Cardiac Life Support (ALS) in anaesthesiology residents and interns not exposed to structured ALS courses. METHODS: 48 residents, and seven interns accepted for training in anaesthesiology, were tested in a spontaneous, blind, cross-sectional, prospective assessment using a recording manikin with validated scoring system, a questionnaire, and 35 multiple-choice questions. RESULTS: 65% admitted not having had any CPR training within the last 2 years. The answers were correct in 55 +/- 14% of the cases, increasing significantly with the length of training (P = 0.001). One-rescuer CPR skills were inadequate: only 13% (n = 7) of participants scored within acceptable limits when using the Berden Scoring system (Berden et al., Resuscitation 1992;13:31-41), which assigned weighted error points to BLS skills. No correlation with skill was noted with increased length of residency, confidence, ER or ICU experience, or participation in CPR-incidents. CONCLUSIONS: Anaesthesiology residents and interns were not able to demonstrate BLS skills properly even while in training and did not recognize this themselves. CPR-related knowledge is poor and increases only incidentally over the years of residency even though participants were frequently confronted with seminars and resuscitation situations, and see protocols daily. The use of multiple-choice questions and the Berden scoring system avoids difficulties in evaluating case-scenario type of tests. We suggest that trainees are motivated to take part in standardized, intensive, recognised ALS courses which emphasize BLS skills and require (re)certification.

Learning cardiopulmonary resuscitation skills: does the type of mannequin make a difference?

Resuscitation (CPR) courses stress acquisition of psychomotor skills. The number of mannequins may limit the 'hands-on' time available for each trainee to practise CPR and impede acquisition of skill. This may occur because expensive, sophisticated mannequins are favoured over individual, simple mannequins. In a blind, prospective, controlled study we compared one-rescuer CPR skills of 165 trainees in two cohorts using their own individual light-weight torso mannequins (Actar 911 and Laerdal Little Anne) and a control cohort with four to five trainees sharing a sophisticated mannequin (Laerdal Recording Resusci Anne). No major significant differences (p = 0.18) were found when using the 'Berden scoring system'. Both the Actar 911 and the Little Anne were compatible with the Recording Resusci Anne. Trainees preferred the individual mannequins. We conclude that the results indicate that the use of individual mannequins in conjunction with a sophisticated mannequin neither results in trainees learning incorrect skills nor in significant improvement. Further analysis of the actual training in lay person CPR training courses and evaluation of course didactics to optimize training time appear indicated.

Development of computer-assisted patient control for use in the hospital setting during mass casualty incidents.

Hospital resolution of mass casualty incidents can have difficulties involving "command and control" and information management, ineffective use of triage classes, and missed diagnostic procedures, leading to lower quality of care. A computer system has been developed to supply continuously updated group and patient data. The system uses barcoded identifiers to represent patients, injuries, facilities, and locations, in order to minimize errors and make exchange of data possible. The system communicates with the permanent hospital information system. This article reports the use of this technology during several experiments and real incidents. Computer registration based on bar codes, despite the greater number of items entered, still showed 25% fewer inaccuracies when compared with handwritten medical charts. Extensive training was shown to be unnecessary. Paramedical personnel judged the automated procedures to be an improvement during the admission of 143 evacuated patients.