5. Commitments

Operating Lease

        The Company rents office space under an operating lease that expires on March 31, 2019. The lease allows the Company to terminate the lease any time after March 31, 2017 without a penalty.

        Future minimum annual operating lease payments are as follows:

                                                                                                                                                                                    

        Rent expense was $52 and $39 for the three months ended March 31, 2018 and 2017, respectively.

Purchase Commitments

        As of March 31, 2018 and December 31, 2017, the Company had commitments to suppliers for inventory purchases totaling $7.1 million and $9.0 million, respectively, of which $0.0 million and $0.4 million, respectively, was committed to Medtronic, a related party.