ipd                package:wavethresh                R Documentation

_I_n_d_u_c_t_a_n_c_e _p_l_e_t_h_y_s_m_o_g_r_a_p_h_y _d_a_t_a.

_D_e_s_c_r_i_p_t_i_o_n:

     Inductance plethysmography trace.

_U_s_a_g_e:

     data(ipd)

_E_X_A_M_P_L_E_S:

     # # ts.plot(ipd)

_S_o_u_r_c_e:

     This data set contains 4096 observations of inductance
     plethsymography data sampled at 50Hz starting at 1229.98 seconds.
     This is a regular time series object. 

     I am grateful to David Moshal and Andrew Black of the Department
     of Anaesthesia, University of Bristol for permission to include
     this data set. 

     This data set was used in Nason, 1996 to illustrate noise
     reduction with wavelet shrinkage and using cross-validation for
     choosing the threshold. 

     A plethysmograph is an apparatus for measuring variations in the
     size of parts of the body. In this experiment the inductance
     plethysmograph consists of a coil of wire encapsulated in a belt.
     A radio-frequency carrier signal is passed through the wire and
     size variations change the inductance of the coil that can be
     detected as a change in voltage. When properly calibrated the
     output voltage of the inductance plethysmograph is proportional to
     the change in volume of the part of the body under examination. 

     It is of both clinical and scientific interest to discover how
     anaesthetics or analgesics may alter normal breathing patterns
     post-operatively. Sensors exist that measure blood oxygen
     saturation but by the time they indicate critically low levels the
     patient is often apnoeic (cease breathing) and in considerable
     danger. It is possible for a nurse to continually observe a
     patient but this is expensive, prone to error and requires
     training. In this example the plethysmograph is arranged around
     the chest and abdomen of a set of patients and is used to measure
     the flow of air during breathing. The recordings below were made
     by the Department of Anaesthesia at the Bristol Royal Infirmary
     after the patients had undergone surgery under general
     anaesthetic. The data set (shown below) shows a section of
     plethysmograph recording lasting approximately 80 seconds. The two
     main sets of regular oscillations correspond to normal breathing.
     The disturbed behaviour in the centre of the plot where the normal
     breathing pattern disappears corresponds to the patient vomiting.

