Does incorrect level needle localization during anterior cervical discectomy and fusion lead to accelerated disc degeneration?

STUDY DESIGN: Retrospective radiographic analysis. OBJECTIVE: To retrospectively review a group of patients undergoing anterior cervical discectomy and fusion (ACDF) to determine the relative risk of adjacent level disc degeneration after incorrect needle localization. SUMMARY OF BACKGROUND DATA: The needle puncture technique is a well-established method to cause disc degeneration in experimental animal studies. The risk for accelerated degeneration because of needle puncture in humans is unknown. METHODS: A retrospective radiographic analysis of 87 consecutive patients after single or 2-level ACDF with anterior plate instrumentation was performed. Perioperative and follow-up radiographs were used to grade disc degeneration according to a previously described scale. RESULTS: Eighty-seven patients were included in the study (36 underwent 1-level ACDF, and 51 underwent 2-level ACDF). Seventy-two had correct needle localization at the level of planned surgery; 15 had incorrect needle localization (1 level above the operative level). There were no differences between the 2 groups in age, sex and length of follow-up. Patients in the incorrectly marked group were statistically more likely to demonstrate progressive disc degeneration with an odds ratio of 3.2. There was no correlation between age and length of follow-up with development of disc degeneration. CONCLUSION: There is a 3-fold increase in risk of developing adjacent level disc degeneration in incorrectly marked discs after ACDF at short-term follow-up. This may indicate that either needle related trauma or unnecessary surgical dissection contributes to accelerated adjacent segment degeneration.

The influence of cardiograph design and automated algorithms on the incidence and detection of electrode cable reversals in an academic electrocardiogram laboratory.

BACKGROUND: Medical errors have been increasingly identified as a major source of morbidity and mortality in both outpatient and acute care settings. Central to the evaluation of many medical problems, the 12-lead electrocardiogram (ECG) is susceptible to both technical and interpretative errors. Proper interpretation, however, is dependent on the quality and accuracy of the acquired ECG. METHODS: We evaluated the impact of both a newly designed electrocardiograph and a newly developed automated computer algorithm on the incidence and detection of electrode cable reversals (lead reversals). The study tested the association of the incidence of electrode cable reversals and the design of the connection terminal. The study was performed during a 7-month period preceding (53,875 ECGs) and after (53,344 ECGs) the implementation of the new system. Electrode cable reversals occurring in various sites of the medical center were tabulated and compared. We then sought to determine if computer detection algorithms could increase point-of-care detection of electrode cable reversals and, thereby, offset the influence of cardiograph design changes. Two commercially available automated detection algorithms were compared for their abilities to identify electrode cable reversals in our study population. RESULTS: During the 7-month postimplementation period, there was a significant increase in the incidence in electrode cable reversals (0.5% vs 0.1%, P < .001). The incidence of reversals for ECGs obtained in the emergency department was twice that of those obtained within the hospital (0.79% vs 0.38%, P < .01). Automated detection of electrode cable reversals from the 7-month study period increased from 38% to 71% (P < or = .0001), using a recently released automated algorithm supplied by the manufacturer. CONCLUSIONS: Electrode cable reversals are a prevalent source of medical errors that receives very little attention by the clinical community. The association of an increase in electrode cable reversals with an altered electrode cable connection terminal, coupled with an increased ability to detect electrode cable reversals using the manufacturer's recently developed algorithms, emphasizes the importance of ongoing research efforts to identify technical errors in electrocardiography.

An unusual case of electrode misplacement: left arm and V(2) electrode reversal.

Accidental interchange between precordial and limb leads, although unusual, can be possible given that some of them share the same color. We present the case where interchange of V(2) and left arm cables produced significant electrocardiographic abnormalities, which created many doubts and discussion within the clinical team.

Recording electrocardiograms using 3-limb lead cables instead of the standard 4: a modification to minimize incorrect electrode placements.

The similarity between and the number of limb lead cables play an important role in the frequency of incorrect connection of limb electrodes. Hence, a modified electrocardiogram (ECG) acquisition procedure is proposed in this brief communication, whereby the left-leg (LL) and right-leg (RL) electrode cables are combined into 1 cable, referred to as combined LL/RL cable. The electrode wires in the combined LL/RL cable are connected to 2 electrodes placed on both sides of the LL. The combined LL/RL cable is unique enough (being thicker) not to be mistaken with the upper limb electrode cables. The proposed modification will not in any way influence the ECG waveforms or amplitudes, and it can be expected to substantially reduce incorrect limb electrode placements.

Electrocardiographic artifact induced by an electrical stimulator implanted for management of neurogenic bladder.

Serial electrocardiograms (ECGs) obtained in a 79-year-old woman revealed consistently sharp regular high-voltage spikes, which were superimposed on her ECG curve, and which were caused by an implanted pelvic electrical stimulator used for the management of a neurogenic bladder, with symptoms of urinary urgency and incontinence.

A flatline lead I results from bilateral arm-to-leg electrode exchange.

A flatline lead I plus P and T inversions in leads II, III, and aVF in a 31-year-old male patient suggested interchange of the arm and leg electrodes bilaterally. Prompt repetition of the ECG with corrected lead placement resulted in a normal ECG and prevented incorrect diagnosis, workup, and treatment.

Electromagnetic interference produced by a hearing aid device on electrocardiogram recording.

An 85-year-old male was implanted with a single-chamber permanent pacemaker because of atrial fibrillation with slow ventricular response. The patient had a chronic hearing impairment and decided to buy a hearing aid device. The MyLink device (MyLink, Phonak, Stafa, Switzerland) is a multifrequency FM transmitter/receiver (169.40-176.00 MHz and 214.00-220.00 MHz) with a neck-loop antenna that is designed to be used in combination with a second FM transmitter, which detects sound, produced by an audio source or person, and transmits this information to the MyLink wearer. These transmissions are subsequently converted by the MyLink and sent to the patient's existing hearing aids wirelessly. Given the proximity of the receiver to the left-sided pacemaker pocket, a concern about possible interaction was brought to our attention. Normal functioning of the pacemaker was observed during the test. However, potent electromagnetic interference on electrocardiogram (ECG) recording was induced when the MyLink loop antenna was placed on top or near the ECG electrodes.

Temporal thermometry fails to track body core temperature during heat stress.

PURPOSE: The aim of this study was to assess the accuracy of temporal scanning thermometry in monitoring internal temperature increases during passive heating. METHODS: Sixteen subjects (5 males and 11 females) underwent a whole-body passive heat stress (water-perfused suit) to increase internal temperature. Temperatures were obtained with a temporal scanner and with an ingestible-pill telemetry system that tracks intestinal temperature. Temperatures were recorded while subjects were normothermic (34 degrees C water-perfusing suit) and every 10 min during passive heating (48 degrees C water-perfusing suit). RESULTS: Heart rate (ECG), mean skin temperature (weighted six-site average), skin blood flow (laser Doppler flowmetry), and sweat rate (capacitance hygrometry) were all significantly elevated at the end of heating (all P < 0.001). Pre-heat stress temporal-derived temperature was not different from intestinal temperature (36.98 +/- 0.09 vs 37.01 +/- 0.09 degrees C, respectively, P = 0.76). However, after 30 min of heating (the greatest duration of heating completed by all subjects), temporal-derived temperature decreased to below the pre-heat stress baseline (-0.22 +/- 0.11), whereas intestinal temperature increased by 0.39 +/- 0.07 degrees C (P < 0.001 between the two methods). After 50 min of heating (N = 11), intestinal-derived internal temperature increased by 0.70 +/- 0.09 degrees C, whereas temporal-derived temperature decreased by 0.29 +/- 0.10 degrees C (P < 0.001). The group average (+/- SEM) R2 and slope between the two methods were 0.29 +/- 0.08 and -0.34 +/- 0.14, respectively. CONCLUSION: These results demonstrate that temporal scanning does not track internal temperature, as measured via intestinal temperature, during passive heating. Given these findings, it is recommended that this technique not be used to assess temperature in hyperthermic diaphoretic subjects.

Ultrasound probe pressure as a source of error in prostate localization for external beam radiotherapy.

PURPOSE: A pelvic phantom was constructed to evaluate the effect of ultrasound probe pressure during performance of bipolar acquisition technique (BAT) for prostate localization for radiotherapy. METHODS AND MATERIALS: A pelvic phantom of a gelatin mold with a water-filled balloon representing the bladder and rectum and a central encapsulated clay sphere representing the prostate was constructed. This phantom was then scanned using planning computed tomography (CT). The geometric information of the phantom was outlined in two planes. The phantom was then scanned using the BAT system with mild and moderate ultrasound probe pressure. Differences in prostate depth between the CT and BAT systems were displayed. RESULTS: A difference of 1 cm between the phantom surface and the prostate could be produced with moderate ultrasound probe pressure. The differences were similar between the CT- and BAT-generated contours and were dependent on the ultrasound probe pressure. CONCLUSION: Care must be taken not to cause any alteration in prostate localization with increasing ultrasound probe pressure when using BAT localization. Increased probe pressure may introduce errors in prostate localization and under dose the target.

Blood pressure measurements by the Keito machine. Evaluation versus office blood pressure by physicians.

BACKGROUND: The Keito machine offers automatic measurements of blood pressure (BP), height and weight on insertion of coins and has been introduced in pharmacies. DESIGN: Cross-sectional study comparing automatic BP measurements by the Keito machine to office BP measurements by physicians. METHODS: Patients scheduled for pre-catheterisation screening participated in the study. Their BP was first measured using the Keito machine, then by physicians. Office BP was recorded as the last of three consecutive BP measurements recorded with one-min intervals after a five-min rest in the sitting position. In a sub-study BP was measured simultaneously during the Keito measurement by a physician. RESULTS: In 390 consecutive patients average BP was significantly lower with the Keito machine compared to office BP measurements made by the physicians (136/75+/-19/8 mmHg versus 141/79+/-21/10 mmHg, both p<0.001). The correlation coefficient (r) was 0.56 (p<0.001) for systolic BP (SBP) and 0.53 (p<0.001) for diastolic BP (DBP). Bland-Altman analysis showed a mean difference (+/-2 SD) for SBP and DBP of -5 (+/-37) and -4 (+/-17) mmHg, respectively. When defining hypertension (HT) as office SBP> or =140 and/or DBP> or =90 mmHg, the Keito method diagnosed 83% of the systolic and 62% of the diastolic hypertensive population correctly. The classification of systolic and diastolic normotensive was correct in 61% and 86%, respectively. CONCLUSION: Agreement between office and Keito BP is poor. The Keito machine underestimates SBP on average by 5 mmHg and DBP by 4 mmHg, which may be of significance for diagnosing HT and starting anti-hypertensive therapy. However, the difference can be much larger in individual patients. Therefore, the Keito machine cannot be recommended for medical screening of HT or as a replacement for follow-up by physicians.

Errores neurorradiológicos frecuentes en TC y RM / Frequent neuroradiological misinterpretations in CT and MR

Se presenta una revisión de las variantes anatómicas normales más frecuentes de ver en cráneo, cerebro y espacios de líquido cefalorraquídeo, que pueden ser malinterpretradas como hallazgos patológicos llevando a la realización de estudios más complejos e innecesarios. En la mayoría de los ejemplos, las variantes anatómicas son solo visibles en TC y en otros casos son exclusivas de RM. El propósito de esta revisión es conocer las variantes más frecuentemente observadas en imágenes de RM y TC con el fin de obtener un diagnóstico acertado evitando la realización de estudios posteriores innecesarios que solo llevan a aumentar los costos en salud de nuestros pacientes.

The extent and implications of sphygmomanometer calibration error in primary care.

AIM: The sphygmomanometer is an essential piece of diagnostic equipment, used in many routine consultations in primary care. Its accuracy depends on correct maintenance and calibration. This study was designed to: (1) assess the maintenance and calibration of sphygmomanometers in use in primary care; (2) assess the clinical, ethical, legal and public health implications of our findings. METHOD: A researcher assessed the accuracy of mercury and aneroid sphygmomanometers in use in 231 English general practices. He also made enquiries about arrangements for the maintenance and calibration of sphygmomanometers. We conducted a small telephone survey in general practices across the country to determine maintenance and calibration arrangements across the country. We carried out a modelling exercise to explore the clinical, ethical and public health implications of our findings. RESULTS: Of 1462 sphygmomanometers, 9.2% gave readings were more than 5 mm Hg inaccurate. No practice had arrangements for maintenance and calibration of sphygmomanometers. Nationally, one of 54 practices had an arrangement for maintenance and calibration. True hypertension is very uncommon in women under 35, a blood pressure which is measured as high is much more likely to be caused by calibration error than by hypertension. CONCLUSION: It is rare for sphygmomanometers used in primary care to be maintained and calibrated. Because of this women under 35 are at risk of misclassification and inappropriate treatment. This has ethical and public health implications. Clinicians using equipment which has not been maintained and calibrated may be medically negligent.