A novel smartphone app for blood pressure measurement: a proof-of-concept study against an arterial catheter

Smartphones may provide a highly available access to simplified hypertension screening in environments with limited health care resources. Most studies involving smartphone blood pressure (BP) apps have focused on validation in static conditions without taking into account intraindividual BP variations. We report here the first experimental evidence of smartphone-derived BP estimation compared to an arterial catheter in a highly dynamic context such as induction of general anesthesia. We tested a smartphone app (OptiBP) on 121 patients requiring general anesthesia and invasive BP monitoring. For each patient, ten 1-min segments aligned in time with ten smartphone recordings were extracted from the continuous invasive BP. A total of 1152 recordings from 119 patients were analyzed. After exclusion of 2 subjects and rejection of 565 recordings due to BP estimation not generated by the app, we retained 565 recordings from 109 patients (acceptance rate 51.1%). Concordance rate (CR) and angular CR demonstrated values of more than 90% for systolic (SBP), diastolic (DBP) and mean (MBP) BP. Error grid analysis showed that 98% of measurement pairs were in no- or low-risk zones for SBP and MBP, of which more than 89% in the no-risk zone. Evaluation of accuracy and precision [bias ± standard deviation (95% limits of agreement)] between the app and the invasive BP was 0.0 ± 7.5 mmHg [- 14.9, 14.8], 0.1 ± 2.9 mmHg [- 5.5, 5.7], and 0.1 ± 4.2 mmHg [- 8.3, 8.4] for SBP, DBP and MBP respectively. To the best of our knowledge, this is the first time a smartphone app was compared to an invasive BP reference. Its trending ability was investigated in highly dynamic conditions, demonstrating high concordance and accuracy. Our study could lead the way for mobile devices to leverage the measurement of BP and management of hypertension.

Intra-patient potassium variability after hypothermic cardiac arrest: a multicentre, prospective study

Background

To date, the decision to set up therapeutic extra-corporeal life support (ECLS) in hypothermia-related cardiac arrest is based on the potassium value only. However, no information is available about how the analysis should be performed. Our goal was to compare intra-individual variation in serum potassium values depending on the sampling site and analytical technique in hypothermia-related cardiac arrests.

Methods

Adult patients with suspected hypothermia-related refractory cardiac arrest, admitted to three hospitals with ECLS facilities were included. Blood samples were obtained from the femoral vein, a peripheral vein and the femoral artery. Serum potassium was analysed using blood gas (BGA) and clinical laboratory analysis (CL).

Results

Of the 15 consecutive patients included, 12 met the principal criteria, and 5 (33%) survived. The difference in average potassium values between sites or analytical method used was ≤1 mmol/L. The agreement between potassium values according to the three different sampling sites was poor. The ranges of the differences in potassium using BGA measurement were − 1.6 to + 1.7 mmol/L; − 1.18 to + 2.7 mmol/L and − 0.87 to + 2 mmol/L when comparing respectively central venous and peripheral venous, central venous and arterial, and peripheral venous and arterial potassium.

Conclusions

We found important and clinically relevant variability in potassium values between sampling sites. Clinical decisions should not rely on one biological indicator. However, according to our results, the site of lowest potassium, and therefore the preferred site for a single potassium sampling is central venous blood. The use of multivariable prediction tools may help to mitigate the risks inherent in the limits of potassium measurement.

Trial registration

ClinicalTrials.gov Identifier: NCT03096561.

Is trauma in Switzerland any different? epidemiology and patterns of injury in major trauma - a 5-year review from a Swiss trauma centre

Switzerland, the country with the highest health expenditure per capita, is lacking data on trauma care and system planning. Recently, 12 trauma centres were designated to be reassessed through a future national trauma registry by 2015. Lausanne University Hospital launched the first Swiss trauma registry in 2008, which contains the largest database on trauma activity nationwide.

METHODS

Prospective analysis of data from consecutively admitted shock room patients from 1 January 2008 to 31 December 2012. Shock room admission is based on physiology and mechanism of injury, assessed by prehospital physicians. Management follows a surgeon-led multidisciplinary approach. Injuries are coded by Association for the Advancement of Automotive Medicine (AAAM) certified coders.

RESULTS

Over the 5 years, 1,599 trauma patients were admitted, predominantly males with a median age of 41.4 years and median injury severity score (ISS) of 13. Rate of ISS >15 was 42%. Principal mechanisms of injury were road traffic (40.4%) and falls (34.4%), with 91.5% blunt trauma. Principal patterns were brain (64.4%), chest (59.8%) and extremity/pelvic girdle (52.9%) injuries. Severe (abbreviated injury scale [AIS] score ≥ 3) orthopaedic injuries, defined as extremity and spine injuries together, accounted for 67.1%. Overall, 29.1% underwent immediate intervention, mainly by orthopaedics (27.3%), neurosurgeons (26.3 %) and visceral surgeons (13.9%); 43.8% underwent a surgical intervention within the first 24 hours and 59.1% during their hospitalisation. In-hospital mortality for patients with ISS >15 was 26.2%.

CONCLUSION

This is the first 5-year report on trauma in Switzerland. Trauma workload was similar to other European countries. Despite high levels of healthcare, mortality exceeds published rates by >50%. Regardless of the importance of a multidisciplinary approach, trauma remains a surgical disease and needs dedicated surgical resources.

Undertreatment of acute pain (oligoanalgesia) and medical practice variation in prehospital analgesia of adult trauma patients: a 10 yr retrospective study

BACKGROUND

Prehospital oligoanalgesia is prevalent among trauma victims, even when the emergency medical services team includes a physician. We investigated if not only patients' characteristics but physicians' practice variations contributed to prehospital oligoanalgesia.

METHODS

Patient records of conscious adult trauma victims transported by our air rescue helicopter service over 10 yr were reviewed retrospectively. Oligoanalgesia was defined as a numeric rating scale (NRS) >3 at hospital admission. Multilevel logistic regression analysis was used to predict oligoanalgesia, accounting first for patient case-mix, and then physician-level clustering. The intraclass correlation was expressed as the median odds ratio (MOR).

RESULTS

A total of 1202 patients and 77 physicians were included in the study. NRS at the scene was 6.9 (1.9). The prevalence of oligoanalgesia was 43%. Physicians had a median of 5.7 yr (inter-quartile range: 4.2-7.5) of post-graduate training and 27% were female. In our multilevel analysis, significant predictors of oligoanalgesia were: no analgesia [odds ratio (OR) 8.8], National Advisory Committee for Aeronautics V on site (OR 4.4), NRS on site (OR 1.5 per additional NRS unit >4), female physician (OR 2.0), and years of post-graduate experience [>4.0 to ≤5.0 (OR 1.3), >3.0 to ≤4.0 (OR 1.6), >2.0 to ≤3.0 (OR 2.6), and ≤2.0 yr (OR 16.7)]. The MOR was 2.6, and was statistically significant.

CONCLUSIONS

Physicians' practice variations contributed to oligoanalgesia, a factor often overlooked in analyses of prehospital pain management. Further exploration of the sources of these variations may provide innovative targets for quality improvement programmes to achieve consistent pain relief for trauma victims.

Evaluation of the GlideScope for tracheal intubation in patients with cervical spine immobilisation by a semi-rigid collar

Application of cervical collars may reduce cervical spine movements but render tracheal intubation with a standard laryngoscope difficult if not impossible. We hypothesised that despite the presence of a Philadelphia Patriot cervical collar and with the patient's head taped to the trolley, tracheal intubation would be possible in 50 adult patients using the GlideScope and its dedicated stylet. Laryngoscopy was attempted using a Macintosh laryngoscope with a size 4 blade, and the modified Cormack-Lehane grade was scored. Subsequently, laryngoscopy with the GlideScope was graded and followed by tracheal intubation. All patients' tracheas were successfully intubated with the GlideScope. The median (IQR) intubation time was 50 s (43-61 s). The modified Cormack-Lehane grade was 3 or 4 at direct laryngoscopy. It was significantly reduced with the GlideScope (p < 0.0001), reaching grade 2a in most patients. Tracheal intubation in patients wearing a semi-rigid collar and having their head taped to the trolley is possible with the help of the GlideScope.

Pre-hospital tracheal intubation in patients with traumatic brain injury: systematic review of current evidence

BACKGROUND

We reviewed the current evidence on the benefit and harm of pre-hospital tracheal intubation and mechanical ventilation after traumatic brain injury (TBI).

METHODS

We conducted a systematic literature search up to December 2007 without language restriction to identify interventional and observational studies comparing pre-hospital intubation with other airway management (e.g. bag-valve-mask or oxygen administration) in patients with TBI. Information on study design, population, interventions, and outcomes was abstracted by two investigators and cross-checked by two others. Seventeen studies were included with data for 15,335 patients collected from 1985 to 2004. There were 12 retrospective analyses of trauma registries or hospital databases, three cohort studies, one case-control study, and one controlled trial. Using Brain Trauma Foundation classification of evidence, there were 14 class 3 studies, three class 2 studies, and no class 1 study. Six studies were of adults, five of children, and three of both; age groups were unclear in three studies. Maximum follow-up was up to 6 months or hospital discharge.

RESULTS

In 13 studies, the unadjusted odds ratios (ORs) for an effect of pre-hospital intubation on in-hospital mortality ranged from 0.17 (favouring control interventions) to 2.43 (favouring pre-hospital intubation); adjusted ORs ranged from 0.24 to 1.42. Estimates for functional outcomes after TBI were equivocal. Three studies indicated higher risk of pneumonia associated with pre-hospital (when compared with in-hospital) intubation.

CONCLUSIONS

Overall, the available evidence did not support any benefit from pre-hospital intubation and mechanical ventilation after TBI. Additional arguments need to be taken into account, including medical and procedural aspects.

[Access to prehospital medical care: organization and utility of the chain of survival]

In order to be effective, access to prehospital care must be integrated into a system described as "the chain of survival". This system is composed of 5 essential phases: 1) basic help by witnesses; 2) call for help; 3) basic life support; 4) professional rescue and transport to the appropriate institution and 5) access to emergency ward and hospital management. Each phase is characterized by a specific organization, dedicated skills and means in order to increase the level of care brought to the patient. This article describes the organization, the utility and the specificity of the chain of survival allowing access to prehospital medical care in the western part of Switzerland.

[An efficient example of a Swiss pre-hospital chain of survival: the state of Vaud model]

The state of Vaud model of the pre-hospital chain of survival is an example of an efficient way to deal with pre-hospital emergencies. It revolves around a centrally located dispatch center managing emergencies according to specific key words, allowing dispatchers to send out resources among which we find general practitioners, ambulances, physician staffed fast response cars or physician staffed helicopters and specific equipment. The Vaud pre-hospital chain of survival has been tailored according to geographical, demographical and political necessities. It undergoes constant reassessment and needs continuous adaptations to the ever changing demographics and epidemiology of pre-hospital medicine.

[Glasgow Coma Scale in traumatic brain injury]

Even 30 years after its first publication the Glasgow Coma Scale (GCS) is still used worldwide to describe and assess coma. The GCS consists of three components, the ocular, motor and verbal response to standardized stimulation, and is used as a severity of illness indicator for coma of various origins. The GCS facilitates information transfer and monitoring changes in coma. In addition, it is used as a triage tool in patients with traumatic brain injury. Its prognostic value regarding the outcome after a traumatic brain injury still lacks evidence. One of the main problems is the evaluation of the GCS in sedated, paralysed and/or intubated patients. A multitude of pseudoscores exists but a universal definition has yet to be defined.

Arrêt de la sédation en neuroréanimation

The reasons for sedation in neurointensive care can be divided into two main groups: (i) general indications, as for other intensive care patients, such as to allow the necessary treatments (therapeutic facilitation), controlling the states of agitations em leader; (ii) specific indications due to the neuro-physiologic effect of the sedatives: facilitation of the control of the intracranial pressure and lowering of the cortical excitability during the epileptic fits and thereby helping the recovery of the cerebral tissue and diminishing the secondary brain insults. It is important to remember that sedation is usually combined with the administration of opioids, which can potentiate the effect of the sedative drugs. The interruption of the sedation can be long- or short-termed. The definitive interruption is possible once the clinical and cerebral state of the patient does not justify any sedation, whereas the brief interruption allows a neurological reassessment. The amount of literature on sedation in intensive care is opposed to the few studies on neurointensive care: in January 2003, the American Society of Intensive Care has published recommendations for this topic without mentioning the interruption of sedation in neurointensive care patients. The aim of this article is to review the literature about the effects of the interruption of the sedation in neurointensive care patients.

ARDS with severe hypoxia--aeromedical transportation during prone ventilation

Severe hypoxia, despite maximal conventional respiratory support, is one of the few remaining limitations to aeromedical transportation. A case of a 35-year-old female, who was referred 36 hours following major trauma for transfer by air to a tertiary center, is presented. At the time of referral the PaO2/FiO2 ratio was 48. Usual manoeuvres to improve oxygenation had only minimal impact. The patient was turned and subsequently transported prone with resultant improvement in PaO2/FiO2 ratio to 260. There were no patient- or transport-related adverse events. The implication of prone positioning during aeromedical transportation is discussed.

Ejection as a key word for the dispatch of a physician staffed helicopter: the Swiss experience

We evaluated the type and severity of injuries and the possible influence of a helicopter staffed by a physician on the outcome of 71 consecutive occupants ejected from a four-wheel vehicle ejected occupants who were cared for by the Swiss Air Rescue Helicopter team from January 1994 to February 1999. The investigation and the data collection were planned prospectively. The following data were collected for each patient ejected from a four wheel vehicle: (1) demographic information; (2) type of injury; (3) vital signs on scene, in flight and at hospital; (4) hospital diagnosis; (5) injury severity score; (6) secondary transfer; (7) length of stay in hospital and on intensive care; and (8) outcome at hospital discharge. A control group included consecutive patients cared for by the same rescue team during the same period but who were not ejected out of their vehicle. Forty-four percent of the ejected patients had a GCS < or = 8, 21% were hypotensive and 22% had respiratory problems. Nine patients died at the scene. A total of 53% of the 62 ejected patients who were transported had an ISS > or = 16. The median ISS was 17. A total of 37% of the patients were intubated at the scene, needle chest decompression was performed in 5% and major analgesia was used in 27% of the cases. A total of 38% of the patients needed surgery in the first 4 h, 34% needed intensive care. No patient needed secondary transfer to the Trauma Centre if they were not brought there in the first instance. The outcome was poor in 27 cases (38%): 17 died and 10 needed transfer to specialised institutions. Non-ejected patients suffered mostly from head and neck injuries (50%) of which 9% were severe (head and neck AIS > or = 4, P < 0.05). Thoracic injuries were less frequent (35%) of which 13% were severe (thorax AIS > or = 4, P < 0,05). The median ISS was 9 for the non-ejected patients, P < 0.05. In conclusion, ejection from a four-wheel vehicle causes more severe injuries and requires a high number of advanced life support manoeuvres. Based on the mechanism of injury alone, patients ejected from four-wheel vehicles should automatically receive a response from the best available pre-hospital team. In our system, this means the dispatch of a physician staffed helicopter.

pH measurements as guide for establishing short-term postpyloric enteral access

Standard antiulcer regimens that use agents such as intravenous ranitidine (50 mg every 8 h) and/or intragastric antacids (30 ml every 4 h) do not seem to preclude use of pH-sensing feeding tubes in our patient population. The cost of placement ($174/successful tube) compared favorably (3-79% less) with the cost of other placement methods used at our institution. Immediate establishment of postpyloric access by this method can decrease delays in instituting nutritional support. Moreover, in patients at increased risk for aspiration, e.g., those with altered mental status, postpyloric tube placement may be beneficial in reducing aspiration occurrence. The equipment is portable and easy to operate, and the placement technique can be easily learned and performed at bedside by nurses and physicians. Whereas we feel that the sensitivity and specificity for intestinal placement are not sufficient to preclude a confirmatory radiograph, the sensitivity and specificity for intragastric placement in our study were both 100%. Our own policy is to obtain a confirmatory radiograph before institution of any nutritional therapy through a central access device (central venous catheter or feeding tube). However, depending on hospital or departmental policy, a radiograph may be unnecessary when intragastric placement is deemed adequate. Finally, this placement method may obviate the need for more intricate and expensive methods of feeding-tube placement.

Intestinal placement of pH-sensing nasointestinal feeding tubes

Intestinal access for enteral nutrition can be achieved by spontaneous intestinal nasogastric tube passage or by endoscopic, fluoroscopic, or surgical placement methods. Each of these methods has limitations that may compromise clinical utility. pH-sensing nasointestinal feeding tubes allow active placement with minimal equipment and expertise; however, this method requires an acidic gastric pH. We sought to determine whether antiulcer regimens used at our institution would preclude intestinal pH-sensing tube placement. Twenty-five patients had 25 (81%) successful intestinal placements in 31 attempts. Observed pH values and calculated pH changes were compared within and between successful and unsuccessful groups by using a Student's t test. Initial, lowest, and final pH values did not differ significantly between groups. The pH change initial-to-lowest (4.7 +/- 0.18 vs 3.6 +/- 0.59, p < .03) and lowest-to-final (5.0 +/- 0.18 vs 3.0 +/- 0.47, p < .0001) differed significantly between groups, whereas the pH change initial-to-final did not. Cost analysis of endoscopic ($782), fluoroscopic ($341 to $382), spontaneous ($167 to $212), and pH-sensing ($162) methods revealed 3% to 79% savings when the pH-sensing placement method was used. We conclude that the antiulcer therapies used in our patient population did not preclude intestinal pH-sensing tube placement. If the pH changes from initial-to-lowest and lowest-to-final were greater than 4, successful intestinal placement occurred in 91% of attempts. Finally, the method was cost-effective at our institution.